DFO - L brarV I MPO - Bibliothèque Il lll I l lIl \Il l 12069715 CONFIDENT IAL ANNUAL REPORT of THE ATLANTIC FISHERIES EXPERIMENTAL STATION THE FISBERIES RESEARCH BOARD OF CANADA 1941 Aîlpendices Page No Canning Fish Salt Fish Fresh Fish Preservation Cod Liver Oil Smoked Fish List of Publications 1 14 36 58 67 69 - 13 - 35 - 57 -.66 - 68 , 70 REPORT OF THE ATLANTIC FISÉERIES EXPERIMENTAL STATION HALIFAX, N. S. for 1941 By S. A. Beatty, Director. For the past three or four years the staff of the Atlantic Fisheries Experimental Station has been reduced considerably below the normal level. In fact, during a con- siderable part of 1940, the research staff of the Station consisted of two senior and two junior workers, During the latter part of the year the staff was increased by the addition of Dr. W. J. Dyer and Dr. A. J. Wood. From January to May we were without the services of Dr. D. B. Cooper, but at the end of that period his duties were assumed by Dr. E. P. Linton, who, because of his previous knowledge of the work, was able very rapidly to take it over and to pursue it aggressively. During the year of 1940 Mr. G. J. Sigurdsson joined our staff as a voluntary worker to investigate problems of bacterial metabolism, On the completion of his studies for the degree of Master of Science this spring, he was taken on as a temporary assistant. Dr. Hess finished his work undor the Lobster Controller in September of this year, and under an arrangement between the Lobster Controller and the Fisheries Research Board his two assistants Mr. A. Hollett and Mr. R. E. S. Homans were assigned to problems concernitg the canning of lobster, in our laboratory. These staff increaseS are reflected in a much greater output of werk and while a large part of our staff is still unfamiiiar w ith the practical aspects of the industry, a considerable part of our work of the present year is capable of commercial utilization and some of it has already been made use of, In spite of our increased personnel the number of problems is not much larger than last year. The choice of new problems was determined by the needs of the country and Empire in the prosecution of the war y the needs of the industry itself, the basic work essential to studies of practical nature and the training and capabilities of our personnel. Hence emphasis was placed on urgent problems that appear to permit of rapid solution, This is not considered a wise permanent policy, but the rapid changes in the industry and the pressing needs resulting from the war outweigh the desire for a long range policy that might ; after some years, show greater progress. The advice of members of the Executive was made available through visits by the Chairman and the Secretary of the Board. While the Subexecutive met only once during the year, the work of the Station has been kept before the Chairman as frequently as possible. 5 The results of the More important studies are given by the researchers themselves in the Appendix to this Report. The following summary shows the coordination of the work, and the possible and actual industrial applications. Canned fish Under the Canned Lobster Controller, Dr. Hess has had two years' experience in the grading of canned lobster. This work has shown the need of a system of inspection based in part at least, on objective standards. The development of suitable standards is a very difficult task, and within the time available only a start has been made. It has been shown that the Armstrong penetrometer, which has been used to advantage in the inspection of canned salmon, gives a reliable measure of the texture of the meat. It was demonstrated also that the salt content of the pickle can be determined rapidly and with sufficient accuracy by direct titration of the diluted pickle. The colour of the canned meat is a very important factor in the de -tDrmination of the value. No mea, have been devised to assay this factor accurately because of the colour characteristics, It has been found that the pigments can be extracted and matched against arbitrary colour standards. This method will probably never be used in routine work, but it may provide a means of checking grading officials, or of settling disputes between graders and owners. The development of such standards is almost essential to the proper grading of the lobster pack. This work should be prosecuted as vigourously 4 as possible if greater emphasis is to be placed on the grading of canned lobster. Several questions have been raised by the work of Departmental officials in connection with the lobster industry, and as many of these have been answered as time permitted.,. The enforcement of size limits in the canning areas has made it necessary to determine the change of body length as a result of boiling.. It has been shown Uhat lobsters of minimum legal size do not shrink more than one eighth inches and hence that lobsters less than six and three eighth inches in length after boiling,were captured illegally.. A serious error in the determination of drained .weight of canned lobster has been shown;, that the drained weight, as determined at presànt, is dependent to a very large extent on the temperature of the canned moat, and that it is possible under present practice to obtain differences from cans, identical except for storage temperature, of as much as three quarter ounces. It is suggested that not only the time of drainage but also the temperature of the product at the time of examination be fixed. The occurrence of magnesium ammonium phosphate has received special attention.. These crystals do not form under all conditions, and it would appear that if the conditions resulting in their formation were known the fault would be 5 eliminated entirely, The phosphate content of the muscle stays constant throughout the whole moulting period but that of the blood undergoes wide fluctuation being highest juot before moulting. One might infer that the stage of moulting might be a factor in the formation of the crystalm, but calculated from the solubility of magnesium ammonium phosphate in water at the hydrogen-ion concentration of the can contents, there is always sufficient phosphate to produce a growth of the crystals. Analyses for magnesium show much smaller concentrations. At present it would appear that sea water or impure salts may be the source of the magnesium in the crystals. The study is being continued and the role of magnesium should be determined shortly. If sea water or impure salts are proven the source of this magnesium, it should be possible to eliminate this defect. Experimental packs of canned lobster designed to show the effect on the finished product of; over cooking, overprocessing, the inclusion of weak, soft-shelled, or dead lobsters, have been made. These will be examined at intervals and the results will be made available at the completion of the work . The problem of transportation of fish to England, without low temperatures, of a quality and at a price the British people are willing to pay, has received considerable attention, Experiments with a more palatable dried fish than 6 that produced at the present time will receive attention in a later section of this Report. The utilization of our numerous canneries might provide larger volumes of canned fish. Because the British market prefers the Icelandic type of pack, it was deemed wise to gain some experience with it, Successful packs were made and we are now in a position to supply necessary information to any interested parties. For the same reason experimental packages of dried fish and dried vegetables for fish cakes were made. The feasibility of putting up such a product has been shown, but it still remains to be seen whether or not the industry as now' equipped can dry either in salt fish dryers or fish meal plants, a fish product equal in quality to that produced on a laboratory scale, or whether our finished product is acceptable to British consumers, Salt fish production When the work on the production of salt fish was, undertaken some three years ago, drying of the product. the first problem attacked was the It was realized that a study of salting should precede that of drying, but pressure from the trade itself, and a lack of suitably trained researchers dictated our course. With the addition of Dr, Dyer to our staff it has been possible to start the work on salting, The first problem attacked was to _determine the factors influencing the penetration of salt and the withdrawal of water under conditions similar to those obtaining in the 7 trade itself. The rates of salt penetration and moisture removal, and the effect of some of the factors influencing these rates are given in Appendix No. 41 The work has gone almost as far as is advisable at this time. During the coming year, the effect of the ions ordinarily contaminating fishery salts will be determined, In the Annual Report for l93,8, Appendix No , 2, Dr. Hess reported that the growth of certain halophiles is more rapid in the presence of high concentrations of solar salts than in the presence of equal concentrations of chemically pure salts. It has been found that the difference in the growth rate is also very striking at lower concentrations of salt, solar salts permitting the most rapid growth, chemically pure salt the least, and the effect of mined salts about half way between the other two The studies of the rate of salt penetration offer a plausible explanation of the occurrence of putty fish. Large cod fish have been subjected to conditions similar to those under which the "putty! forms in the trade. It has been found that this type of spoilage is the result of holding the fish at high temperatures for a time sufficient to allow bacterial penetration into the deep tissues, and salting at a temperature sufficiently high to allow these bacteria to decay an area in the centre before the salt reaches that area in a concentration high enough to stop their action. • 8 During the past summer, the temperatures were sufficiently low that practically no puttied fish was produced. A careful survey is being made for the occurrence of these fish in packages being ë ut for boneless, As the fish are cut, the buyers inform the Station, the proportion of putty$ the producer, and the time of purchased a6Curate We have had alb temperature records for a typical putty producing area for the summer of 1940. The Director has already discussed reme- dial measures with the majority of the important producers and will attempt to visit all of them before next June. Those interviewed have expressed a willingness to co-operate with us, in an endeavour to eliminate these losses, or to reduce them to a negligible amount, We expect that even with normal temperatures next year, the amount of putty fish will be small. One year's successful operation should be sufficient to finish the problem in so far as the Station is concerned. A start has been made towards the development of a salt fish, sufficiently low in salt to be acceptable to the British market, and sufficiently dried to stand transshipment without refrigeration, The preliminary work gives every indi- cation that a product only slightly inferior to fresh fish can be produced. Present equipment plus additions for brining could produce dried fillets equivalent to about 2,5,000,000 pounds round fish annually and at a cost lower than bacon. There would be a saving of about 80 per cent of the original 9 weight of the fish, and the finished product is almost 40 per cent protein. The work is being prosecuted as rapidly as possible, The work on drying of hard salted fish has been practically finished except for the effect of humidity of the air. The data shown in Appendix No. 10, gs well as previous data show that an efficient dryer should operate in two stages, the rapid removal of water until the surface effect makes rapid air flow no longer of advantage, and the removal of the rest of the water in a dryer of low air volocity and large capacity, This work has been seriously interrupted by the application of the results to commercial practice and by staff changes. It is hoped that it can proceed without further interruption to its completion, probably three months hence. The study of the drying characteristics of fish of lower salt content should be much more rapid, as the major difficulties have been overcome, and the limits can be narrowed more rapidly. The dataon air temperatures and humidities d our coast has been supplemented through the co-operation of the Department of Transport, Eastern Air Command, Halifax. 1 We obtained in all continuous readings throughout the summer from nine stations covering all the Maritimes as far north as Caraquet, These results have not been worked up and cannot be worked up by our present staff without thestoppage of work 10 urgently needed, . It is hoped that assistance can be obtained to put at least a minimum of these results in an available form during the present fiscal year. Fresh fish preservation For the past year little was done on studies on the bacterial decomposition of fresh fish because of our reduced staff. The work was resumed this year and is making progress. Previous work was done on gross samples with the flora picked up by the fish during processing . The present attack was made by studying the action of bacteria, one strain of organism at a time, on simple media, using the resting cell technique. The degradation of glucose has been studied quite intensively and lactic acid is now under investigation. Glucose has been broken down to lactic acid, acetic acid, and formic acid, ethyl alcohol, carbon dioxide and =e—methyl carIiiol. The type of breakdown is influenced by the hydrogen-ion concentration, more lactic acid being produced in acid reaction. results suggest that the sugar is first broken into two of three carbons each, The »tee&eideA omo Because of its slow rate of breakdown lactic acid is probably not one of these. The breakdown of lactic acid itself may throw further light on this type of fermentation, Some years ago, the quality of the fish in the retail stores in Toronto, poor. Gbviously Mlntreal and Halifax was found to be very either radical changes in the processing of 11 freezlng of the the fish, or thc%fish are necessary to bOlig the qlality up to a minimum level. As a result of the action of the Department of Pensions and National Health in enforcing the Pure Food Laws with respect to preservatives, the quality has fallen off. The producers are endeavouring to increase the sales of properly frozen fish but the prospect of disposal of the major part of cod and haddock fillets in the frozen state is not bright. Therefore any enhancement of keeping time must be brought about by (1) reducing the bacterial contamination, (2) speeding up the time between capture and final disposal, (3) maintaining minimum temperatures, But in spite of all reasonable care in handling it is felt that the trade c annot better the product to the minimum standard of quality, During the year, the use of bactericides and bac- teriostats were studied, and the only useful contribution to the list previously known were glucose and ethylene oxide, Glucose appears to have some peservative effect due to its trimethylamine oxide and protein sparing action. It is probably more effective than benzoic acid, and it is the only preservative found that complies with Pure Food laws, but it is not r ecommended as being sufficiently effective, Ethylene oxide has been found to be very effective as a bactericide e killing off as much as 99 per cent of the .contaminating floral under conditions readily duplicated in commercial practice, Preliminary feeding experiments in concent ra tions higher than that used on fish show no visible toxicity to mice. Because 12 this method may be effective in the prevention of s:lime on bacon, our data has been given the National Research Council. If the procees is âpplicable to the bacon trade, it is hoped that further studies in both laboratories on the possible' toxicity of the gas or any end products of the gas will be made. At the commencement of the present hostilities it was expected that the lobster trade would be seriously affected, and we were asked to determine the feasibility of shipping frozen lobster meats to markets on this continent. These experiments are now finished. Frozen lobster cannot be made to resemble in physical characteristics, by known method of freezing or storage, the uncooked frozen meats. Whether or not the consumer is willing to accept this prodluct remains to be proven, but it is definitely inferior to the fresh meat. Cod liver oil production The production of cod liver oil has almost reached the maximumpossible with equipment now available to the trade but only a small proportion of the livers produced aboard the schooners can be used for the production of medicinal cod liver oil. The oil produced aboard the schooners engaged in the salt fish trade is of very low quality, fit only for industrial uses, while on the schooners engaged in the fresh fish trade, in spite of the use of preservatives, the greater 13) part of livers is fit only for the production of a veterinary oil. The livers from these sources shoùld produce under normal production a minimum of 160,000 gallone,worth as a finished gestearinated product between 0.00,000 and 400,000, It has not been possible to persuade captains of fishing vessels to put aboard the ordinary steaming equipment because of the large volume of fresh water required for the boiler, It has been found that fine disintegration of the livers eliminates the need of steam, the oil separating at a temperature of about 170 ° F. This temperature can be obtained by means of closed coils in the cooker, the condensate being returned to the boiler. This modified equipment will require about half the steam horsepower of the steam cooking, and eliminates the problem of large, volumes of boiler water, The livers can be ground suffic- iently fine by means of a hammer mill, but the power demand is somewhat high for equipment aboard the schooners, A grinder of our own design is under construction and it can be reported on orally at the Annual Meeting. A source of supply of suitable boilers has been found and plans for a cooker are under way. It is hoped that this equipment will be ready for trial aboard fresh fishing schooners before the salt fish production starts this spring, In connection with the preservation of livers, it has been found that sterile livers during storage produce a, 14 darker oll than those heavily contaminated with bacteria, Therefore any liver preservative must be not only bacteriastatic but must also prevent the action of the liver enzymes themselves. Experiments have shown that if intimately mixed with finely ground liver, soda ash to one per cent of the total weight of liver acts as an excellent preservative Several types. of grinders, suitable for this purpose have been found. The companies during the present year have produced a large quantity of oil not glite of medicinal grade. Steam distillation as practiced for the deodorisation of fats in general was found to produce an oil of excellent flavour, while even fresh oil was improved. Equipment is being installed for the deodorisation of these oils, adding about 50,000 gallons to our production of medicinal oilt This is not the direction in which we ordinarily would have desired the industry to move, but we believe that improvements in the quallty of un livers brought in will render itA necessary to tcleaniupf Oil of low quality. A number of plant control experiments wore made on the destearination of cod liver oil. As a result of these experiments one firm has remodelled its whole production equipment and- is installing destearination equipment. A second firm will probably install such equipment during the coming calendar year, 15 Throughout the Whole of this work, the results of the investigation at Prince Rupert have been of great assistance, and Bulletin No. 59 has enabled the trade to get a clear picture of the processes involved. The work in co-operption with the Department of Pensions and National Health on the vitamin value of some of our fish liver oils has been finished in so far as this Station is concerned, We have assisted the Department of Fisheries in the transport of raw material to OttaWa for further assays. Fish smoking No experimental work was dune during 1940! A type B smoke-house, erected from plans furnished by the Station, did not function. While the faultwas found to be due mainly to errors in construction, the smoke velocity was Pound to be at a minimum for this type of smoking. Examination of a second house which had functioned properly for some years Showed velociti.es much less than we had previously believed. Since the margin between failure and successful operation is so narrow, it is probably not wise to recommend further installations. As a result of the experience in air flow gained during the work on drying, it ehould be possible to produce a smoke-house with a positive smoke-flow, The interest in the production of smoked fish is reviving. It is not deemed wise to allow an investigation into fish smoking to interfere with the work on drying, It is our present intention to modify 16 our mnall plant model fish dryer into a smoker. controlled flow This can be done with little labour, If the experiment succeeds we shallbe given a stop gap until the work on drying reaches a stage that will permit us to drop it. I not, it would in our opinion, be wisest to finish the work on drying before that on smoking is given serious; attention. Due to the illness of the Director during the winter and spring, field work of the Station has suffered« Nova Scotia and Prince Edward 'bland were covered thoroughly but no work was done in New Brunswick. The east coast of New Brunswick and the Grande Riviere Station will be visited during early December. The short courses for cannery foremen given during February and March were poorly attended, and until more interest is shown they should not bo repeated. Dr. Hess and the Director attended the Conference for Fishery Inspectors at Shediac during September, 4eading discussions on canning, cannery grading, the inspection and grading of canned lobster, salt fish preparation, and control of tredt and tdun , and !putty', und fish plant sanitation. The staff supplied technical information in the construction of equipment for fish freeaing, fish smoking, cod liver oil production, deodoriaation and destearination of oils, general plant sanitation in the production of salt and fresh fish, 17 tr. Hess cooperated with the Department of Fisheries by reinspecting samples in all cases of underweight canned lobster detected by Fisheries Inspectors during the 1941 season, as part of our suggested sc hema for the s tandardization of weight inspection. Three Progress Reports were issued during the year and material is at hand for another issue which will appear early in the New Year. Because the additions to our staff have been made relatively rocently,, the volume of publications is not large, but the work in several fields is approaching a stat -1 that should result in a larger list for the coming yeart 18 Scientific Staff of the Atlantic Fisheries Experimental Station 1941 S. A. Beatty, Ph.D. Director Ernest Hess, M.A., Ph.D, Associate Bactc,eriologist W, W. Johnston, M.A., Ph.D. Assistant Biochemist E. P. Linton, M.Sc., Ph.D. F.C.I.C. Asst, Physical Chemist A, L. Wood, BoSao, B.E. âcientific Assistant in Engineering W. J. Dyer, M.Sc., Ph.D. Scientific Assistant in Biochemistry A. J. Wood, M.S.A,, Scientific Assistant in Bacteriology G. J. Sigurdsson, M.Sc0 Temporary Assistant in Biochemistry APpENDICES SECTION CANNED - FISH (With the assistance of Mr. A. H011ett , and Homahe of the staff of the Cannsd LotietPr Controller) Al Appendix No ,l LUSTER The course of the investigations undertaken during 1941 was determined in the main by the types of defects unrsovered in the grading of canned lobsters ln ,ler the Canned Lobster Control Scheme of 1940, WEIGHT OF CANNED LOBSTER MEAT In the determination of the weight of the meat in canned lobster, as set forth in the "Regulations govrning the inspection of canned fish and shellfish and the oeeration of canneries", the cans are freely drained for a period of not less than one minute r and not e7ceeding one and onehalf minutes. While this arbitrary time limit has been set e no account has been taken of the effect the temperati)re of the can contents has on the amount cf pickle draining off during this pericd, Experiments have shQwn thpt the viscosity of the pickle depends partly on the amount of so l uble protein subatances present, and increases with age of the can as shown in an earlier publication, but mal-Ily on the temperature of the pickle In most older cans ex&mined the pickle formed a gel at 10 ° C and even at 15 ° C, the picke is not freely flowing in many cans * At 18-22 ° C, the pickle flow- fairly freely, and at a9°C A a it is very fluid so that the average amounts of pickle draining off are of the order of 1 2 5 mle at 10 ° C., 29 ml. at 15 ° C., 38 ml. at 18.5 ° C. and 50 ml, at 22°C 0 As only a fraction of the pickle adheres to the meat itself, a part of it adhering to the can and the parchment lining, these figures do not represent the differences in weight of lobster meat at different temperatures, These amount to the following average values, taking 180,5 ° , an arbitrary normal: 28 ° C. as - 855 gme; 22 ° C, .... -4525 gin .; 15 ° C. .... 4. 4.6 gm,; 10 ° C. + la gme The total difference between 10 ° C, and 29 ° C , may therefore be an average of 20.5 gm, or nearly 3/4 ounce, In newly packed cans this value would be about halved since there is less variation in viscosity with temperature in them, In fairness to all concerned (packers and consumera) tests for canned lobster should be made only on cane have been held within a certain temperature range -- weight tha 18-23 ° C. -- for several days, or, if this is not feasible, the results should be corrected according to the temperature of the can content at the time of examination. It has also been assumed by some packers that the weight of drained lobster meat would be favourably affected if the cans were inverted some time before opening -tem, Accurate tests on this point have shown that no signifIcant change in weight occurs based upon such a manipulation, E. Hess and A. Hollett A3 STRENGTH OF PICKLE In the old Regulations governing the operntion of canneries, the maximum strength of the salt brine which is added to canned lobster was set at 2 - per cent, This was erroneously based on the fact that the total salt content of fresh lobster is approximately 2i per cent without taking into consideration that not all of this salt is sodium chloride and that it therefore gives to the muscle a much weaker salt flavour than a ai per cent sodium chloride content would do, In addition, during the processing of the cans this brine is considerably diluted by water that is cooked out of the lobster mea, and some of the salt is absorbed by the lobster meat to give it a pleasing salty flavour, Tests have shown that a brine containing 8 per cent sodium chloride when added to the can will result in a pickle in the finished product after several weeks' storage of not more than a per cent, and this final concentration Tas found most pleasing in a tasting panel, E, Hess and A, Hallett MAGNESIUM AMMONIUM PHOSPHATE CRYSTALS IN CANNED LOBSTER During 1941 an investiganan of the probable causes and contributingfactors in the formation of ma€;nesium ammonium phosphate crystals in canned lobster was begun A4 Phosphoruà content of lobster muscle and blood In order to arrive at the limiting factors which affect the formation of these n struvite n crystals in canned lobster, the natural variation of the phosphorus content of lobster muscle and blood was considered, as it has been observed that lobsters canned in certain areas show a much greater tendency toward crystal formation, than those put up in other regions, a fact which can hardly be attributed to different canning technique, although the latter factor ba not ignored in the investigation. With this in view, a determknation was made of the inorganic phosphate and organic phosphorus content of the blood and muscle of lobsters during the pre-molt p post-mclt and inter-molt periods, Analyses have revealed that there is a wide variation in the phosphorus content of the blood. (Ail figures given here have been computed as phosphorus), Immediately preceding the molt, due no doubt to the absorbtion of phoephorus from the shell, it reached its highest peak, when the total phosphorus content of the blood was found to be 27 mgp per cent of which 13 mg. per cent was fm the form of Inorganic phosphate, During the inter-molt period, the concentrations were approximately half the above figures, It was after molting, when the new shell had not hardened, that the loweat phosphorus content was found, Inorganic phosphorus in the blood dropped to less than one mg, per cent and the total A5 was less than 3,5 mg 0 per cent. In general there was a greater concentration of phosphorus in the blood of the male than in that of the female for the same period. It was found that the concentration of phosphorum in the muscles was not affected by the molt cycle and that it was relatively constant, The inorganic phosphorus content was about 0,17 mg 0 per cent, the organic about 0411 mg. per cent, Analyses were also made of both the pickle and the meat of cannedrlobster 4 some cans of which contained deposits of struvite crystals. In no instance was the inorganic phosphorus content of the pickle or meat less than 0.05 mg , per cent, Ëxince the solubility of magnesium ammonium phosphate is about 0,02 - mg, per cent, it is evident that unless e due to the presence of colloidal substances, the solubility is greatly increased, there is present in the meat and pickle sufficient inorganic phosphorus for the deposition of fairly large quantities of struvite crystals; in fact in far larger amounts than are aCtually found in canned lobster, This statement would be equally true if the pickle were slightly acid at pH 6.9 whereas potentiometric determinations have shown that the average hydrogen ion concentration of canned lobster pickle is pH 7.0, with very limited variations, The fact emerges, therefore, that phosphorus is not a limiting factor in the formation of magnesium ammonium phosphate crystals in canned lobster. •.6 Magnesium content of lobster muscle Preliminary alalyses have indicated that the concentration of magnesium in lobster muscle is much less than one-tenth that of phosphore&Q. Since magnesium is present in sea water in greater concentration than this, it seems probable that the washing of meat in sea water preliminary to canning, and its use in the making of pickle may have a contributing influence on subsequent struvite crystal formation in the canned product * In fact, some experiments carried that out several years ago showed , the crystal formation was more A prevalent in cans in which sea water or fishery salt was used in the pickle, than when dairy salt was used. Further investigations are being conducted along these lines. E. Hess and A. Hollette TEXTURE, FLAVOUR AND APPEARANCE A series of experimental lots of canned lobster were prepared to study the effect of such factors as overcooking of live lobsters, overprocessing, inclusion of "sick", soft Shelled or dead lobsters upcn the texture of the canned lobster meat. Another series was put up to investigate the influence of sea water and fresh watwr on the appearance (colour of pigment and white meat) and flavour of the canned lobster meat, particularly after prolonged storage. These cans await periodical examination. E. Hess A. Hollett R. E. S. Homans A/ OBJECTIVE TESTS FOR GRADING CANNED LOBSTER In the routine grading of canned lobster during the 1940 and 1941 seasonm only three objective tests were used, namely determination of vacuum, weight of total lobster meat and weight of "fine meat". As the use of as many objective tests as possible in the grading of any product is desirable the possibilities.ef other tests for canned lobster have been explored. Texture The Armstrong penetrometer (as used in the inspeotton of canned salmon) was tested on canned lobster, using the tail part, i, e,, bottom part of the can e The results appear to give a reliable index of the average firmness of the tail meat. They differ from the organoleptic test in so far as the latter emphasizennot so much the average firmness but judges the whole can by the softest tail present. A change in the standard for the organoleptic test would bring the two into closer agreement, Flavour or saltiness The use of a salinometer is not feasible on account of the presence of appreciable quantities of soluble proteins and derivatives in the pickle, Titration of a small amount of highly diluted pickle. with a wuak solution of silver nitrate can be carried out in a few minutes and the results are reliable. AS Odour If conditions are properly arranged the odour o an be judged with fair accuracy. One of the difficulties encountered in judging the odour of canned lobster is that the odour, once the can has been opened e is extremely volatile. To overcome this a piece of glass apparatus has been constructed which is fitted over the can immediately after opening. This prevents the escape of the odour. The estimatEhon of the odour is facilitated by the use of an attached glass tube e the open end of which fits the nostril. The nostrils are used alter- nately in estimating the concentrated odour sniffed through the tube. Colour Various attempts have been made to devise an objective test which will serve satisfactorily in the estimation of pigmentation in canned lobster. Such a method has been worked out, based on the acetone extraction of a weighed quantity of fineIy ground lobster claw meat, extract is then made. A colorimetric determination of the Suitable colour standards„ using a mixture of amaranth and napthol „Span also be prepared which will accurately indicate the degree of pigmentation thereby replacing the need of a colorimeter, The results obtained by using these methods indicate that they are suitable as a referee method in the grading of colour in canned lobster. Investigations are now being carried on to determine A9 the feasibility of measuring the degree of pigmentation by comparing the finely ground claw meat on a tintometer, Such a method is extremely simple andrapid enough to serve as a routine objective test, Whether any or all of these tests are feasible and valuable for routine grading romains to be determined. Their immediate vIlue rests in their use in cases of dispute between different graders or in borderline cases between two different grades b E. Hess R. E. S, Homans A. Hollett EFFECT OF COOKING ON BODY LENGTH OF LOBSTERS In the course of their duty of - enforcing lobster size limits Departmental Officers are occasionally reaching lobster' canneries at a time when no live lobsters are on han d ? but batch of 'freshly cooked canning lobsters may be available for inspection. The question then arises whether the length of the cooked lobster may be assumed to be the same as it was before cooking, The result of a test on a considerable number of sinall canning lobsters (6,1/4 . 6e,3/4,,1ody length) was that about one-third did not change in length during cooking l about onethird shrank 1/16 of an inch , and one-third shrank 1/8 of an inch, From this it may be concluded that freshly cooked AIX> lobsters of less than 6.5/8 inches body -1,neth were under legal size (6i inches) before cooking,' but that-botretere .,.. between 6.3/8 and 6* inches may or may not have been 61 inches long before. cooking* E. Hess AU Appendix No , 2 ICELAND PACK CANNED FISH As it was reported to us that the se-celad "Icelunge pack of canned cod (haddock, hake) was more acceptable in the English market than our flaked fish, "Chicken Haddies", the preparation of this product was tried. The essential dif- ference in the twe products is that in the preparation of "Chicken Haddies" gutted fish are skinned, brined and steamed, and the edible parts picked out afterwards by hand and packed into the cans, while in the "Iceland pack" the fish are fillotted and the skinned fillets are brined and cut into pieces the length of the can height, (1 lb. flats). The fillet pieces are rolled, usually two together in a piece of parchment paper, steamed, drained and packed, three wrapped packages to a can. In tàis method the fish muscle does not flake apart and conseggently gives a product of a much more attractive appearance, and suitable for a greater variety ot ways of serving than the flaked fish. Proper brining, steaming and processing procedure, using suitable parchment, resulted in a very acceptable product. E. Hess Ala .toppendix No 3 POWDERED PIST1,. 101271i MIXTURE It has been suggested that in order to save weight and space in shipping food, particularly fish, to Great Britain during the war, dried ground fish might be used with other dried and ground ingredients to have a ready-to...fry material for fish cakes after simply adding water to the mixture and forming the "battern into cakes, A number of formulas were tried out usina: Groundieckfsh Ground dried cooked potatoes Dried whole egg Ground dried vegetables Ground dried onions Flour Salt with gratifying results. Ground and dried cooked potatoes were superior to potato flour. flavour could easily be obtained. Fish cakes with a pleasing The only factor that differed in comparison with ordinary home-made fish cakes was the texture, which since all ingredients were of a finely ground nature, had less body and was more of the consistency A 13 of corn mea), pan cakes. However this cannot be considered a serious drawback, in view of the many advantages of the product, particularly for export. The tests were made with cooked fish and cooked potatoes which had been air dried on a small laboratory scale; it remains to be determined whether commercially dried potatoes and fish are equally suitable. In the case of fish it would be a question of steam.drying in a fish meal apparatus or air drying in a properly adjusted artificial salt fish dryer, E. Hess SECTION II SALT FISH-- A14 Appendix No. 4 SALT PENETRATION OF FISH MUSCLE The increasing importance of salt fish in the fishing industry along with the recent trend towards slack salted fish, makes it essential that more knowledge be obtained of the factors affecting the salting of cod and similar fish. Various workers have dealt with the salting of herring but relatively little has been done on the less fatty fish such as cod, hake and pollock. The rate of salting is known to be.influenced by several factors, e. go, kind of salt, temperature, brine con. centration, thickness of fish, freshness of the fish, ratio of penetration rate through skin and flesh. Virtually nothing is known of the giantitative influence of these factors, and in experiments carried out through the past year several factors have been defined. Penetration rate in general The results of a large number of experiments on the penetration of salt into cod muscle immersed in saturated brine (pure sodium chloride) at temperatures from 10 °C, to 2.0C, are summarized in figure 1„page A00, One to two weeks are required for 'striking through', and the effect of thickness of the fish is well shown. One to three days are necessary for A15 the salt content of the centre portion to reach 10 per cent and the importance of this in allowing spoilage is pointed out in the report on putty fish (see Appendix 7)e Distribution of salt The gradient of salt concentration from the surface to the centre has been determined in practically all cases, This gradient is very steep particularly in the first day or two after salting, when differences of 10 per cent or more per cm, may be observed, Typical curves are shown in figure ae page A a0, Penetration through skin Contrary to general opinion, several experiments have shown that the aalt penetrates through the skin equally as fast as through the cut flesh surface, the difference in rate, If any p being less than the sampling error, Temperature Those in the industry have stated that fish strike faster in warmer weather but no data. have been available, Numerous experiments on the rate of salt penetration from O'C. to 25'C 0 have shown considerable correlation with temperature. For illustration a few results at temperatures of 5 ° C 20 ° C, are reported in the following table, and A 16 SALT CONTENT PER CENT CENTRE AVERAGE Temperature 1 day 2 days 5 days 1 day 2 days 5 days ec. 5.0 8.1 16.8 1,1 4.0 14,1 20°C, 7.2 10.2 16.8 3,5 7,2, 14.9 The difference are of the order of two and three per cent, which in the case of the central part of the fish, represents a200 per cent increase between 5* and 20°0, at one day and almost 100 per cent at two days. At five days there is practically no difference, as might be expected. urine concnntration In pickled and brined fish this factor is especially significant. The experimental results, partially illustrated in figure 3, page A 20, show that at two days the salt content of the fish is about 1 per cent less for 84° pickle and a per cent less for 70° pickle, than for Saturated brine, while the difference is 2 and a per cent respectively at five days, Freshness of fish Since cod muscle softens appreciably with deterioration during storage, it would be expected that salt absorption would be affected. Experimentally, faster penetration was found with increasing staleness of the fish muscle. Several fish were stored at 0°C., 15°C., and 20°C., for about 24 hours A17 until the fish samples at 20°C , were on the point of The sample at 15 ° C. was slightly stale, and spoilage. the fish at 0°C. was unchanged ., as judged by organoleptic tests. The fish were then placed in saturated brine at 10 ° C., and the results of average analysis at l e 2 and 5 days are recorded in the table. SALT CONTENT . P: R CENT Condition 1 day 2. days 5 days Fresh 8.4 9.9 16,2 Stale 9.1 12.3 18,6 11.1 12.9 19.2 of fish Spoiled While considerable differences are shown, the increase in penetration rate is not sufficient to permit pickling of fish in poor condition with any certainty of success, as witness the considerable putty fish losses. Moisture removal In all cases molsture and salt were determined concurrently, moisture decreasing as the salt content of the protein-moisture-salt complex increased. In fact the relation between salt uptake and water loss is almost linear, case of fish immersed in saturated brine. in the The relation cor- responds nearly to the equation y = -1.34 x 82.0, where y Is A18 per cent moisture and x is per cent salt , although con.i àiderable variation is evident. KnoWledge of the rate of moisture removal is essential for calculation of the rate at which salt is dissolved, due both to the absorption of salt by the fish and to dilution of brine by the extractel moisture, in a tank full of pickled fish, To date the results of this investigation have been very useful, and if further work is to be instituted on the production of slack salted fish for overseas trade, they will be essential, Determination of the effect ef various salts such as calcium and magnesium compounds, has still to be under. taken, and also a comparison of the various impure commercial salts is needed to complete this phase of the problem. It should also be added that, due to pressure of more directly pr actical problems at this period, insufficient attention has been paid to a stUdy of the physical chemistry of the migration of sodium and chloride ions in fish muscle, and of thd chemical nature of the salt - water . protein complex in salted:fish muscle. This latter is intimately bound up with drying problems. W. J. Dyer Fig. 1. ABSORPTION OF SALT BY FRESH COD SALTCONTENT PER CENT' Average Analysis of Whole Fish =1Analysia of Centre Only 4-- 3 4 5 6 DAYS IN PICKLE 7 8 9 10 11 1. F1. 1. Av, -,. - - r 1 11 Fish et 1" Fish. 3 1: JT 1 Di =-1 8 , r --e, 6 6 4 4 2 2 0 0 0 -1 2 3 1 2 3 A 20 Fig. 2 , SALT DISTRIBUTION CURVES la r. \ 16'A '-, . N. ,/ --„, , . 14-. \\''.. , \ ., ; ,. . %-. la ;-', 1 \ •,,, E-4 N gli 10 , -. ,, . E-4 \ ;, .:‘,..„ e . o 8-• \ ; E-1 E rn \\ 4-. 1 .... 5 days _...•-enr )4 7vf / 1 .--. .,e.... a days ....- . % ., '\.. 1 day ._ . A .. ,/ / 0,_ 0 2 1 5 4 3 6 DEPTH - CM. Fig. 3. EFFECT OF BRINE CONCENTRATION ON SALT PENETRATION ao Cod - 18 all thick - Average Analysis - 15 ° C, 15 days 16 SALTCONTENT OFFISH-% 14 ,- ..---5 days 12 ..," ,:. ../ r. .--,-.„-- 10 7 8 - .,. -'. . . . . . ,-* , , -.15-- ----- ________----- ....„---. ,-----' " I. day ------------ _-- _...--- 6 a, days ..„-- ___:2„----- - ....• ..... , /- ‘; 4 !- 1 L.. _1 1 o 14 84 70 SALT CONCENTRATION OF PICKLE - % SATN. 28 4Z 56 100 A al Appendix No. 5 . SWELLING OF COD MUSCLE IN SALT SOLUTION Our knowledge of the proteins present in cod muscle and their behaviour in the presence of sodium chloride is insufficient for anything but a superficial interpretation of the salt penetration and moisture loss data on salt fish, and of the drying of the cured product. In addition, a study of protein denaturation, and the effect of salt concentration, time, temperature, and dehydration on this phenomenon seems to be indicated for the slack salt fish problem, and perhaps also for frozen fish flavour studies• The effects of salt and hydrogen ion concentration e singly and combined, on the swelling of finely ground cod muscle have been determined, and a few results are plotted in the figure, page A 22.. The curve obtained with ordinary fishery salt lies between the one Ëiiiienfor pH 6 and that for pH 8, and parallels the weight changes observed when cod muscle is placed in brine. The curve suggests that f coagulation, and in this case perhaps also denaturationt of the protein by salt might not be appreciable if the salt concentration is kept below about half-saturation. These data may assume considerable practical importance in attempts to market dried fish of low salt content. • They also show the need of basic work on the ahemistry of the proteins In fish.musale, W. J. Dyer A 22 EFFECT OF pH AND Na.C1 ON SWELLING 4.8, 5 446 Pi 4, k5. 4 o 4. , 2 i to VOLUME- a g. MINCED COD MUS CLEIN40 _1 W 4,0 4 1 l 3,8 1 pH 8 3,6 1 pH 6 » -11 1 "- \ \ \ . 2 - /7/ ./// Y 440 - J, \ \ pH 5 7 l 2,8 • 26! , 1 i ■ 1 a.4 .\ , \ // 2,2 \ \ , \\ \ / 1 Ns. ,/ \\,, : \' , ...1 I 1,8 • 0 . 10 CONC. OF , 15 L____ 20 SOLN. - ge NaC1, _1 25 30 per 100 g. H20 Satt .à, Appendix No. 6 INVESTIGATIONS ON THE SALT TOLERANCE OF CERTAIN FRESH FISH SPOILAGE BACTERIA Hess (in press) has observed that certain of the common fisherles salts possess varying powers to inhibit the growth of the bacteria commonly associated with the spoilage of fish. In an attempt to obtain quantitative evaluation of these, studies have been made on the tolerance of certain purb,2cultures isolated from spoiling fish muscle to various concentrations of these salts under several growth conditions. Preliminary to the studies on salt tolerance the growth requirements of the cultures have been investigated in some detail. The salt tolerance work has shown that solar salts are the least bacteriostatic, with mined salts in an inter. mediate position and chemically pure sodium chloride showing highest activity. Perhaps of greater interest is the finding that solar salts actually stimulate growth very markedly in concentrations, commonly used for the treatment of fresh fish. This stimulation may amount to several hundred per cent during the first 48 hours of pactfflal growth. A4 By transferring cultures through broths contining increasing amounts of salt it has been possible to demonstrate. that all the cultures investigated adapt themselves more rapidly to growth in the presence of high concentrations of solar salt. The relationship of this finding to slime formation in salt fish and to the development of putty fish may be significant. Qualitative observations have suggested that there is a change in the metabolism of the cultures when they are grown in the presence of solar salt. Preliminary experiments indicate that this may be due to traces of metallic impuritiea in tâese salts,. Further work is necessary for the ,.. ..omp:.,eta elucidation of the stimulatory effect noted and for a propar • evaluation of the various fishery salts. A. J. Woo cR A25 Appendix No. 7 PUTTY FISH INVESTIGATION It was noted in the Annual Report for 1940 that losses due to putty fish are considerable, and it is especially pertinent at this time that these should be avoided. The condition is found in pickled cod and hake during the warmer season, principally along the Prince Edward Island and the Northumberland Straits shores. The condition has been produced experimentally for the first time, in large cod, at this Station. As noted by the industry, putty is obtained at temperatures over 70 ° F. and its incidence is increased by diminishing the quantity of salt used and raising the temperature of pickling. Other work (see Appendix No. 4) has demonstrated that periods up to three days are required for the salt concentration in thick fish to reach 10 per ment in the central layers0 High temperatures with low salt concentration mitigates in favour of a rapid multiplication of various contaminating bacteria. Chemical and bacteriological examination of the putty portion of the fish revealed a marked increase in the number.,: of bacteria and a parallel increase in their metaboliC% decomposition products. With the reason for the condition estab. Mailed, it has been possible to follow its development with A6 time, To do this the total numbers of bacteria as well as the number of bacteria capable of hydrolyzing casein in agar were determined. The caseolytic counts were made in an effort to detect any macro-change in the bacterial flora. The determination of trimethylamine served as an indirect confirmation of the bacterial counts. Changes in the amount of soluble nitrogen were estimated by the use of the tyrosine reaction. Surface pH values were obtained at the time of organoleptic examination. From the results of these determinations it was evident that the various values increased steadily from the outset. This usually required from one to three days, dependent upon the rate of salt penetration and temperature. Heavy pollution of the fish muscle with bacteria, rough handling, and holding at elevated temperatures prior to salting, and during the first three days of salting is apparently the primary cause for fish losses from this type of spoilage. W. J. Dyer A. J. Wood A27 Appendix No. 8 DRIED SLACK SALTED FISH Preliminary work has been carried out on the preparation of dried fish of much lower salt content than that produced heretofore. This work was undertàken in an effort to produce fish dried sufficiently for shipment overseas and of a quality acceptable to the British consumer, using equipment either already on hand or easily procurable. Fish only eight hours in saturated brine have been dried under a2rtificial conditions without any occurrence of spoilage, These fish before drying contain 8-10 per cent àalt, though actually the greater part of the salt is near the surface. If these fish are dried to about 50 per cent water content, the salt content rises to about 15 per cent. This product would probably compare with bacon in keeping quality, and its palatability is excellent. The protein& do not seem to have been denatured appreciably, at least not sufficiently to affect adversedly moisttlre regain and cooking ellality, some samples dried to about 50 per cent water content comparing very favourably in flavour with the original flab.. To date only sufficient data have been obtained to indicate a definite possibility that a satisfactory procesa 8 can be developed. Before production on a commercial scale can be undertaken. e the optimum conditions for salting and drying in r elation to palatability and keuing quality of the finished product must be determined. W. J. Dyer A ee Appendix No. 9 TEMPERATURE AND RELATIVE HUMIDITY RECORDS Temperature and relative humidity measurements for various points in the Maritime'Previnoes.haye been continued along the.lines'outlined in the 1940 Annual Report, The psychrometers on loan from the Salt Fish Board the Station at the end of the 1940 season wercondit a At the' beginning of June 1941, recorders were installed at Halifax, N. Se, Lunenburg, and Souris, P, - E. I. Caraquet N. B., Precautienp were taken in their installa tien in an effort to avoid repetition of last season's difficulr ties. Accurate psychrometric data are being obtained by the Meteorological office of the Department of Transport, and through their kind co-operation their recerde from Hdlifax, Liverpool, • Yarmouth, Sydney, N. S„ and Moncton, N. 13, are available to uele Several methods for arranging the psychrometric data • have been:investigated. A very conVenient way of r °cording and • prepgmting the information, is by plottl,ng dry bulb and dew point temperatures and relative humidities on a time basis, print of a , seetion of ene of these graphs is attached. A sample A complete analysis of the data eve4lable require's the full services of one man. ' At the present •Unle no worker is available to carry on this analyaià, E 0 P. Linton A'e L. Wood A 30 /00 ...■••■■■■ ■■■■■••••• 70 6.0 1■■■•■••■ 416 ,e/v (5, /71./e/7 tv, S. rlicrhfo. / eihe. 20 — 1 0 90 1 DA ke P01774; 7F i np&roft,/ -e and .1-/el;fax/ 99/. 80 6o • ç•1 1:) _re 30 (;) "110./e ■ f \ I 1 144lay 2? AF ir. s, fve,hii, - I I I I 1 I I 1 Al Al Al /V A,/ ke / v. fris 1+ -My 28i --*1-: ikey 29 ---,---.1-" /4:9/ _34:, .H, '''.-« .'.? d.‘, H /7 A/ s. ..w. 7,747e. i M ev . ///7/f7 - )"W(/. Appendix No. 10 SALT FISH DRYING The investigation of salt fish drying has been continued on cut samples of kench cured cod using the appa. ratus designed for t his purpose. An improved recording balance using a Thyraton Relay has been developed which records weight loss with an accuracy of one twentieth of a gram, ?revious drying results have been reviewed and tabulated and were used to direct further investigations. The data showed that it was not always feasible P. duplicate results. At first these variations were ascribed to faulty technique in using collodion to inhibit drying from the edge& and back of the samples. Paraffin wax,which prevents evapora- tion, was substituted for the collodion but variations still exist. It appears that these discrepancies represent either differences in the fish themselves or in the location with respect to the grain of the fish, from which the sample is taken, Fifteen drying experiments, each one including several samples, were made at a constant relative humidity of 50 per cent. Dry bulb temperatures of 60 ° F., 70°F. and 80.F. and air velocities of 200 and 450 ft./min, were used.' Samples were out from the thick part of selected kench cured cod having an A32 average water content of 56.5 per cent and 19 per cent salt. Four types ofexposed surface were studied. Razor cut surface (Figure 1, curves A, B, C,) These samples were free from skin and bone and the exposed surface was carefully cut smooth and flat with a razor. Natural cut surface (Figure 1, curve D) This is the washed surface originally exposed when the cod is split before curing° Skin surface (Figure 1, curve E) In these samples only the washed skin surface of the fish was exposed to the drying air. Ground pressed surface (Figure 1 $ curve G) Salt cod free from skin and bone was ground to 1/8 inch size and pressed into cakes. Each experiment was continued for about two days using constant drying conditions. Various methods for analysing and plotting the data were tried in an attempt to determine the drying coefficients and mechanism of drying for salt fish . A signifi- cant method of plotting is shown Ill figure 1, in which the fractional free water content of the sample is plotted against time semilogarithmically. experiments. lehe curves are the mean of several Each curve falls into two parts, the first section, from zero to 550 minutes, being elliptical and the second part, from 550 minutes on, being a straight line..; A33 During the first 550 minutes of drying it seems probable that a parabolic moisture distribution is being set up in the sample and the characteristic hard surface is formed. The straight line portion of the curves indi- cates that during this period drying falls into one of the following classifications: (a) Controlling factor: resistance to surface evaporation, Log.(fractional free water) Time (Coefficient of surface evaporation) (Thickness of sample) (h) Controlling factor: Resistance to liquid diffusion, Log.(fractional free water) Time 3(diffusivity of ater) (thickness of sample) e Consideration of curves A, B and C, in which the effective thickness of the samples is 7, 14, and a mm., respectively, shows that Log.(fractional free water) varies Time inversely with the thickness of the sample. Thus the drying of these samples falls into that classification in which surface evaporation is controlling. Hence, the drying time would be reduced by increasing the air velocity, or decreasing the relative humidity. The interesting fact is that under the air conditions studied, the rate of loss of water is not controlled by diffusion of water from thick parts of the fish to the surface layer, but presumably it is the thin, dried A3 crut at the surface of the fish that- inhibits evaporation of watwr to the surrounding air. Within the accuracy of the experiments the drynte curves for dry bulb temperatures•of 60p., 70PF. and 80 0P, and ar, r velocities of 200 and 450 fte/Min_wiere Identical with If velocities much lower,than 200 ft */Min. are used curve A. an unsatisfactory type of surface is produced, Curves A. D e E and G illustrate the influence of the type of txpoised. surface on the drying rate. The skin (curve E) dries roughly about 50 per cent as fast as a razor cut surface (curve A) and about 45 per cent as fast as the - natural cut surface (curve D) of the fish. The pressed ground fish (curve G) dries considerably faster than the other typesdf surfqices and obviously does not follow the same type of drying as the cut sample* The experiments will be continued on cut samples until optimum drying conditions are determined* The results will then be checked using'whole fish in the Turbo:dryer* E. P. Linton • 41. L. Wood 1 /00 ,9.5" I ----I .96 I 1 ,(95- •-80 D2 1 ,7e evate--/- C_17rele Heavy Suited, 'tench-cared Cbcel 5ane/cile5... (Sean' - /0547/-;e17/77;c ) 5b7, /7.19, Air or &CI 80 de,Y. .20,0 ftper: fie». SU tfC,7 fri .6o te7 Fmcfk;nal 1911 /, _se i.;776/7 keoed. 1. fryer-id" Qa eb ficeze.i --c-ut" Surfoce A. ..5 • c, t t secen,) we ge 2 r bet 76. 1/5ç.' Sexaz ., $1,e 3&.Z .9É, Seefee Seine ) —.1v.e.e-ol-cat Surfee://q 5-9,enzi off: 1/0. .91,, . 5...c.n.), WI': • /, 2 9,-. ...5-ce*ere i /..e8- ..,,Crie., We; ?..9.3gr: 6. - - - - - Grocied; Pf-eSSeeci) .2). r _______ .c. -7:-. çl ---:-:'#fie. tk 41.50 1 et.>0 ' Mieutes. 7;ra 1 1 1 /Sao eaces SECTION III FRESH FISH PRESERVATION A6 Appendix No. 11 THE METABOLISM OF BACTERIÀ CAUSING SPOILAGE OF FISH Investigators at the Atlantic Fisheries Experimental Station and others have found that the decomposition of fish muscle is primarily the result of the action of bacteria, In the present work, the metabolism of some of these bacteria in pure culture has been studied in the hope of elucidating its nature, A great number of cultures were isolated from slightly spoiling cod muscle. By growing them in broth containing trimethylamine oxide, about 20 per cent were found to reduce the oxide, This is of interest since the reliability of the trimethylamine test for spoilage has been estioned. For further studies of their metabolism several reducers and non-reducers were selected, They belonged to the genera: Achromobacter, Pseudomonas, and Micrococcus. Their action on glucose and lactic acid was investigated. Throughout the; work non.proliferating or "resting cells" were employed, the suspensions being prepared in . the ordinary manner. The uctIvity activity of the suspension was found to be directly proportional to the concentration of the cells, Before attempting to identify all the products of fermentation the effect of changes in certain experimental A7 conditions was investigated, since it appears that this aspect has scarcely received sufficient attention from previous investigators. A comparison of aerobiosis and anaerobiosis showed tâat the rate of fermentation of glucose was noticeably faster in the anaerobic system, and further. more that the presence of air had a certain definite effect on the products of fermentation. Thus there was in seneral less lactic acid produced from glucose anaerobically than aerobically. The hydrogen-ion concentration has a very pronounced effect on the fermentation. In a series of experiments where fermentation was carried out at various hydrogen-ion concen.a trations it was found that the yield of lactic acid from glucose was in general quite low at a high pH, but it increased very materially as the pH was lowered. In one representative experiment the yield was about 20 per cent at pH 8.1, but it rose gradually tp about 90 per cent at pH 4.6. These results were rather unexpected, but the same trend was demonstrated with several cultures, although in general the difference was not qlite so pronounced. The rate of fermentation was also greatly effected by the hydrogen.ion concentration. In most cases, ta21)H value below 4.5 was almost completely inhibitory, but as the hydrogen. ion concentration was decreased the rate of fermentation rose to a maximum, usually at about pH 6.8. Raising the pH further A8 to 8.1 usually did not cause any appreciable fall from the maximum rate. The products of fermentation of glucose were identified and their relative amounts were determined,• This was done by preparing 300 ml. of the fermentation system at pH 7.2 in a 500 ml. Erlenmeyer flask, incubating for twenty-four hours at a5 0 c. and then analysing the contents. The results for certain repreeentative cultures are shown in table I. The effect of the hydrogen-ion con, centration is shown in the case of Cultures 59 and PJ1 5 there being less lactic acid produced at the higher pH and correspondingly larger amounts of the other products â In the results for Culture 5321, the effect of lowering of the pH, due to acid production during fermentation, , is illus, trated, Where more glucose is utilized the pH has fallen more, causing a shift in the proportionate yields of the products, An indication of the mechanism of fermentation le furnished by the results for Culture 5321. TUis culture produces almost exactly equimolecular amounts of acetic acid and formic acid as well as of ethyl alcohol and carbon dioxide, suggesting that these products probably originated through the fission of a 3-carbon intermediate. Usually such a clear-cut relationship was not observeds A9 The trimethylamine oxide reduced by most of the reducing cultures amounted to between one and two millimales per millimole of glucose fermented. The presence of peptone in the fermentation system was in certain cases found to accelerate the reactione It appears from the results obtained by previous investigators that lactic acidffunctions as the chief source of energy for the bacteria during the initial stages of the decomposition of fish muscle. It was therefore surprising to find that most of the bacteria investigated utilized lactate very slowly. Several cultures did) however, break down the lactate sufficiently to permit the analysis of the products. In every case tested ) carbon dioxide was the chief product derived from lactate ) the yield with different cultures varying from 60 to 100 per cent. This is entirely contrary to the opinions of previous investigators regarding the fate of lactic acid in fish muscle. They believed that it was broken down to equimolecular amounts of acetic acid and carbon • dioxidee An interesting observation was the much more vigorous reduction of trimethylamine oxide in the presence of lactate thah in the presence of glucose . Values as high as 5.8 milli. moles Of oxide reduced per millimole of lactate fermented were obtained. reattione In general the pH rose during the course of the A40 The lactate metabolism is being investigated further eand it is hoped that the results obtained will furnish substantial information regarding the chemical processes in spoiling fish muscle. A. J. Wood G. J. Sigurdsson „. .Table 1. Culture init pH. 59 pH 7.5 Products of fermentation of glucose by representative cultures. Quantities are expressed in millimales per 100 ml. and in percentages of the glucose carbon metabolized. Unitof meaSure ment Glucose used Lactic acid Acetic acid Formic acid Ethyl alchhol mM 1.36 1.08 39.7 0.73 17.9 0.78 9.7 0.56 9.30 0.00 0.00 0.87 58.9 0.1& 5.85 0.12 2.72 0.19 8,55 0.00 0.00 Carbon dioxide Total recover; Acetyl _ of methyl glucose carbinol carbon 76.6 mM % 0.74 pH 7.5 mM % 1.35 0.70 26.0 1.24 30.6 0.52 19.1 0.62 15.3 0.00 0.00 0.028 1.4 _ 92,4 pH 5.5 mM % 1.86 2.77 74.5 0.45 8.06 1. 1 0 9.85 0.26 4.66 0.00 0.00 0.035 1.2 98.0- mM % 8.86 7.74 43.7 4.55 17.0 &.04 5.74 1.18 4.43 2.6a 4.95 mM % 4.90 3.55 36.3 2,10 14.5 2.14 7.10 0.60 4.10 0.59 2,0 2.47 66.5 mM % 1.60 0.70 21.9 1.06 21.9 1.02 12.5 0.33 6.2 0.35 5.7 2,30 68.5 pH 5.5 PJ1 - 5329 pH 7.2 5321 pH 7.2 (final 5.9) pH 7.2 (Final 7.0) 76.0 75.8 > e ri A 42 Appendix No. 12 FISH SPOILAGE TESTS The use of the tyrosine test for the estimation of the state of preservation of fish has been suggested but it has not as yet been applied to code It depends on the increase in soluble protein decomposition products, principally tyrosine, tryptophane and hydrogen sulphide which arise mainly as a result of bacterial activity but possibly due in a smaLl measure to autolysis. The optimum conditions for carrying out the test on cod muscle, involving considerable simplification of the original procedure with no loss in sensitivity, have been established, The tyrosin value increases steadily with time of storage, and appears to gtve values parallel to trimethylamine and surface pH. The test shows promise of being very useful but as yet insufficinnt data have been accumulated to warrant a definite statement of its correlation with the deterioration of the fish, An increase in inorganic phosphate was also noted along with the increase in tyrosine and since this value may be determined much more readily, it may prove a more practical rapid test. cated, Further investigation of this question is indi- A43 As haa been noted by Dr. A. J. Wood (Appendix No. 13),with pH, values given by surface samples show better correlation with organoleptic tests than the samples of the whole fish* W. J. Dyer A44 Appendix No. SURFACE pH AS AN INDEX OF SPOILAGE FOR COD FISH MUSCLE During the past few months determinations have been made of the pH at the surface of cod and haddock fillets at various stages of spoilage. It has been noted that samples taken within 2-5 mms. of the surface show marked differences in pH depending upon the state of freshness of the fish. Similar determinations on samples prepared from the entire thickness of the same fillets failed to demonstrate like differences. This result is to be anticipated since the focal areas of spoilage must occur at the points of heaviest bacterial pollution, In those areas trimethylamine production is proceeding at its most rapid rate and consequently the pH moves to the alkaline side. The fillets tested to date have ranged from pH 6,3 or lower for fresh fish to pH 8.5 for spoiled. These values, as would be expected, parallel the trimethylamine exactly. The chief merit of the surface deter- mination is to be found in its simplicity and speed. In all cases thus far studied it has paralleled the available tests for spoilage. A. J. Wood A45 Appendix No. 14 INVESTIGATIONS ON BACTERIOSTATIC DIPS FOR FRESH FISH During the past year a number of bacteriostatic dips for fresh fish have been examined and tested° These have included nitrites, borates, benzoates and certain commercial preparations offered to the industry by the fishery supply houssa. In general, the examinations have been of a routine character with the exception of one commercial product, Avonex, which was studied in some detail. Previous investigations at this Station have been made on the value of oat flour (Avenex) as an anti-oxidant for lobster meat and to some extent for fresh fish. On theoretical grounds it seemed unlikely that Avenex would be of value as a preservative for the non-fatty fishes. While the material ha s proven merits as an inhibitor of autocatalytie oxidation it seemed doubtful that this quality would delay the growth of th a common spoilage bacteria, Fresh fillets treated with several concentrations of Avenex were stored and examined at frequent intervals. It was found that the dipped fillets kept somewhat longer than untreateçl ones but when spoilage had begun it proceeded at a more rapid rate. Chemical analyses of the Avenex concentrate showed, as was anticipated, a relatively high concentration of reducing A 46 sugar. Dips prepared to contain glucose in concentration equivalent to the reducing sugar in the Avenex were used to treat cod fillets. It was found that these dips markedly delayed the onset of spoilage ap measured ,by orgaboleptic tests. Repetition of the experiments on several occasions confirmed the preliminary work. The exact mechanism for the improvement in quality brought about by the glucose is not immediately evidentl Other udies on the metabolism of the more common fresh fish spoilage bacteria have revealed that, on the average, o'w:a moles of trimethylamine oxide are reduced per carbon atom of glucose fermented while with lactic acid 1.2 moles are reduced per carbon atom e Hence it would seem possible that the excess of glucose present in the surface layers of the dipped fillets exerts a sparing action on the trimethylamine oxide thus inducing an improvement in keeping time. Bacterial counts show that there is no decrease in bacterial numbers in the glucose dipped fillets, Further work is necessary for complete elucidation of this effect, A. J. Wood A47 Appendix No. 15 THE VALUE OF CERTAIN GASES FOR THE STERILIZATION OF FRESH AND SALT FISH Innumerable attempts have been made to devise a satisfactory treatment for the preservation of fresh and salt. fiSh; In general the methods developed have involved a bac- teriostatic or bactericidal dip composed of some toxic chemical agent. It Can be safely said that none of these has proved entirely satisfactory from a commercial point of Tiew, During the past ten months a. new approach to this problem based on the toxicity of certain gases for fish spoilage bacteria has been attempted. The following agenta have been tested: ether, chloroform, methyl chloride, methylene chloride; ethylene and ethylene oxide. The pnly ona of these which has fulfilled all requirements has been ethylena oxide.and consequently a thorough study of this gas has been made.. The work on ethylene oxide has been based on the premise that the bactericidal activity of the gas weuld be greatest using a vacuum system of processing, The cost and difficulty of producing and maintaining a reduced pressure depends upon the reduction required.. A series of experiments have been carried out to determine the extent of evacuation A 48 required to give a maximum destructioh of contaminating bacteria. The fish were treated with 25 ems of ethylene oxide for 25 minutes using various degrees of initial evacuation . The results are shown in table I. TABLE I Degree of Evacuation ems, of mercury BACTERIA PER GRAM OF FISH AFTER SUBSEQUENT STORAGE AT 10C, for 5 days 10 days 30 40 150,000 25,000 2,000,000 1,200,000 5,0 60 15,000 9,000 200,000 15,000 70 4,000 9,000 14,500.000 25,000.000 Control (Untreated) From these results it is evident that the efficiency of the treatment increases with the vacuum drawn before admission of the gas. As with other bactericidal agents it is probable that the concentration of ethylene oxide will be a determining factor in its lethal action. Fish were treated with various concentrations of the gas under an initial vacuum of 70 cms , for 25 minutes ! * The results are recorded in table II. This and other stated pressures are in centimeters of mercury, A49 TABLE II BACTERIA PER GRAM OF FISH Gas pressure Cms, of Immediately After 5 days' treatment storage at 10 ° C 1 aCtor mer cury Control (untreated) 10 15 20 . as 30 280,000 22,000 3,950,000 266,000 9,200 1,600 32,500 7,700 , 1,000 1,000 2,500 1,500 A gas pressure of 25 to 30 ems , of mercury gives a reasobable destruction of the bacteria. The influence of exposure time was determined by treating fish under an initial vacuum of 70 cms. with 25 ems , of the gas. The results are given in table III. TABLE III BACTERIA PER GRAM OF FISH Time of expo sure After 5 dayst Immediately after treatment storage at 10 ° Ce Control (untreated) 240,000 7,000,000 " 106,400 58,800 1,750,000 600,000 30 " 40 " 600 2,300 110,000 40,000 10 20 minutes A50 From the results of these experiments treatment with 25 ems , of gas for 25 minutes with an initial vacuum of 70 ems, is sufficient to greatly enhance the keeping quality of fresh cod fillets. The data recorded in the above tables have been obtained a number of times with complete agreement, Since ethylene oxide forms an explosive mixture with oxygen it would be advantageous to remove this hazardt. The e xplosion hazard can be reduced by dilution of the gaa with carbon dioxide without reducing the efficacy of treatment. All of the work described above was carried out under laboratory conditions. To test the process under semi-corn- mercial conditions a chamber was constructed of a size sufficient to treat 140 pounds of fish fillets packed in their usual wooden shipping containers, Results of numerous tests made under these conditions have been in complete agreement with those obtained in the laboratory, It is worth while to consider the ethylene oxide treatment in relation to the qualifications demanded of an ideal preservative. (1) The preservative must be highly toxic or lethal for all organisms associated with fish spoilage. The experiments which have been outlined indicate that ethylene oxide meets this requirement quite adequately. Other experiments using pure cultures of fresh and salt tish spoilage bacteria and molds prove that the gas is lethal in even lower concentrations than those required on fish muscle. A 51 (a) It must possess a low degree of toxicity for con. sumers of the treated fish. Fish which had been treated with one atmosphere pressura of the gas for 60 minutes was fed to a colony of mice for sixty-two days. No ill effects could be noted in the general condition of the mice nor could any visible effects Perhaps the best proof that no be noted on autopsy. residual toxicity exists has been obtained by inoculating a great variety of pure cultures of bacteria on fish that had been heavily treated with the gas. In every case the grew without any measurable delay. This would cultures seem to be excellent proof that no residual toxicity exists. It b. as been suggested that the ethylene oxide might be converted to ethylene glycol through interaction with the water. The exact state of the toxicology of the latter There compound is not clear from the existing literature. is general agreement that its presence to the extent of about 5 per cent in pure solution has no apparent toxic effect. Determinations have been made on the total weight From these of gas r-equired for the treatment proposed. values the maximum possible concentration of glycol which could be formed if all the gas were converted to this compound is approximately .06 per cent. If one atmosphere pressure of the gas J‘ e used for 60 minutes of treatment this value would be increased to approximately 0,1 per cent. Evidence has been obtained to show that a large portion of the gas is removed at the end of the treatment when a final vacuum is drawn. Thus the actual residual gas or glycol is much lower than the approximated values even above, On the basis of the available information of the pharmacology of ethylene glycol this maximum' value is far below that The above which can be considered to have significance. discussion has been based on the assumption that the ethylene oxide is converted to glycol. The available literature on the ethylene oxide-water reaction is contradictory. Experiments carried out here indicate that at normal temperatures and at the hydrogen-ion concentration of fish muscle this reaction proceeds quite slowly. Additional information of considerable value could be obtained by further studies on this reaction. If the ethylene oxide is not converted to glycol then the possibility of the gas remaining in the fish as a solute must be considered. That this is highly improbable is fairly well demonstrated by the fact that the fish after gas sterilization will immediately support the growth of all bacteria tested. This despite the fact that very low concentrations of the gas are required to kill the sanie organisms. In summary it may be said, on the basis of present data, that the ethylene oxide process meets the second r equirement. A52 (3) It must penetrate through the contaminated sections of the fish muscle. This requirement is fully met since the muscle may actually be rendered sterile through treatment under the conditions described, (4) It must not impair in any way the appearance or quality of the treated product. A close scrutiny of all fish that have been treated has failed to reveal any deleterious effects on appearance Only with extreme gas concentrations forae or flavour. prolonged time can a slight whitening of the surface be It should be noted that all investigations observed. have been conducted using cod and haddock in the fresh or salted state. Its effect in this respect on fish such as salmon remains to bêt determined. (5) It must be commercially possible from the economic point of view. It is difficult to arrive at an accurate cost figure for Using the best available data the gassing treatment. and allowing a safety margin of some 200 per cent, estimates show that the entire cost of treatment will be well within the limits demanded by the industry. As mentioned at the outset several other gases have been studied t some extent but in general they have been much less effective than ethylene oxide. A great many other& remain to be tried and work is progressing on these as supplies bocome available, If gas sterilization becomes commercially possible it would be very desirable to make a fumdamental study of the exact mechanism by which the gas exerts its lethal action. This aspect of the problem has received little or no attention since it is felt that such studies must await further practical investigations. A. J. Wood A53 Appendix No , 16 PRESERVATION OF LOBSTER BY FREEZING On the outbreak of the war the market for a great part of the canned lobsters produced in the Maritimes was lost. Since this product could no longer reach England and the continent, and since at that time the Canadian and American markets had not been developed to their present extent the trade was anxious to find ne youtlets. It was pointed out that a limited market exists for lobster meata which were cooked, then packaged and sold either fresh or after being frozen. As it seemed unlikely that any method could be found for greatly prolonging the maximum storage period for unfrozen lobster, it was decided to direct our attention to the preservation of the meat in a frozen condition. The trade was already preparing limited quantities or this product. It was reported, however, that after a few months in cold storage, its quality had fallen greatly, the objection being that such lobsters became spongy and tasteless. An investigation, under rigidly controlled conditions, of the effect of both the rate of freezing and temperature of storage, was therefore decided upon. Penetrometer measurements to determine the extent of the undesirable change were tried but fOund unsatisfactory, as there was no correlation between A54 penetration and the r esults obtained from a tasting panel. Similarly methods involving cutting the tissue proved useless. Finally it was noted that the frozen meats lose water much more readily than the freshly cooked product. It was therefore decided to use this as a measure of quality, particularly of the "sponginess" of the product. Claw meat was also found, as a rule, to lose slightly more water under the seine conditions than tail muscle. The figures shown In the following table are for tail muscle only. In all caaes the live lobsters were cooked for twelve minutes in boiling water, then shelled, the meat washed and drained, and then frozen either quickly or slowly. When slow frozen, the lobster meat reached a temperature of -15°C, in two hundred and seventy minutes, when fast frozen,in fifty minutes. The frozen lobster meat was stored at either -15C., -10°C. or -5 ° C. The accompanying tabl.e shows the amount of water which could be expressed by subjecting 100 gram of the tail muscle of lobster to a pressure of 1,000 gram for a period of thirty minutes. The same apparatus to hold the muscle and the same technique were used throughout. The table shows that the amount of press juice which can be expressed from muscle increases with the period of storage. The anount of , press juice from the brine frozen or qlick frozen product wam always slightly lower than from the more slowly frozen product« A55 The amount of press juice obtained after only eight days* storage at -15°C. is almost 70 per cent greater than that from the unfrozen article. It is significant that the amount of press juice is almost as great after two to three months , storage f six months. Tasting panels composed of the laboratory workers almost unanimously chose the fresh unfrven meats to any which had been frozen for even twenty four hours and none preferred the frozen meats to the unfrozen product . There was no correlation in preference for meats stored at the three temperatures studied. Likewise there was no correlation in preference for vacuum packed meats over those packed without vacuum, Tasting panels detected no difference between air and brine frowen meats. Ice crystals form in the meat during freezing. These injure the coagulum formed when the meat is cooked, and permit the juices to escape on thawing. This was demonstrated by cooking egg white, freezing, and storing it at .15°C. for ten days, After this period, from 100 gram of egg white, 29 c.c , of press juice were recovered, rt appears therefore that the loss of texture parallels the increase of press juice, Since the freezing process and a very short storage period cause a large increase in press juice it is believed that no storage conditions which might be stipulated will improve the flavour or texture of frozen cooked lobster Ieats. It is not presumed however that the losses in flavour A6 and texture are necessarily attributable to the same reaction. The former may be due to some chemical change in the flavour-lending substances themselves, whereas the available evidence leads one to the belief that the change in texture Is attributable to a physical alteration in the muscle brought about by the freezing process. The claws and tails from live lobsters were frozen fresh. cooked. After four days , storage at -15 ° C. these were The meat was very "short", adhered tightly to the shell and could not be removed in one piece. It had very little flavour and apparently the juices had separated out in the freezing process. W. W. Johnston A57 Air frozen. No vacuum Brine frozen. No vacuum Storage Temperature Press Juice ml. Storage Temperature Press Juice m1. Storage Period Days 0 2 3 8 60 95 134 195 -15° C. -15 ° C. -15°C. -15 ° C, -15°C. -15 ° C, -15 ° C. 6.0 8.0 7.2 10.1 17.5 22.0 16.8 23.6 0 83 117 195 -15 ° C. -15°C. -15 ° C. 6.0 14.3 18.2 17.8 0 95 195 -10 ° C. -10 ° C. 6.0 18.0 23.2 0 95 195 -10°C. -10 ° C, 6.0 15.6 15.7 0 95 195 -5 ° C. -5 ° C. 0 95 195 -5 °C. -5 ° C. Storage Period Days 6.0 25.0 30.1 (incipient decomposition) 6.0 20.5 26.1 (incipient decomposition) VACUUM PACK Brine frozen Air frozen etorage Period Days 0 62 195 Storage Temperature -: s'_, -i5 ° C, -15 ° C, Press Juice ml. 6.0 10.0 19.3 Storage Period Days 0 83 195 Storage Tempera.. ture Press Juice ml. -15°C. -15°C. 6.0 14,S 14.1 SECTION IV -C 0-D. LIVER OIL A58 Appendix No. 17 PRODUCTION OF COD LIVER OIL The usual method of preparing cod liver oil consists of placing the cod livers in vats and injecting live steam into them. and broken up . In this way the livers are cooked Considerable oil rises to the top of the kettle and is then skimmed off. According to the trade on an average throughout the year 100 pounds of fish liver will yield around 40 pounds of skimmed oil and 8 pounds more can be recovered by pressing the liver residues. more are lost in the residues. About 8 pounds Because of the prolonged period in the press and difficulty of keeping the press cloths clean this pressed oil is unfit for medicinal use. It was therefore obvious that if all the oil in the livers could be recovered as a first class product the return of medicinal grade oil would be increased by about 16 per cent. An investigation into the recovery of oil from thess liver residues showed that approximately 90 per cent of the residual oil of a grade opal to the original, could be recoVered by the following process. The residues are ground to 40 mesh size and three volumes of hot water (about 80°C.) and sodium hydroxide to the extent of one per cent of the liver residues are added. The whole is stirred slowly, after A59 which the oil floats to the top, and much of the undigested liver residues settle to the bottom. The saine treatment of fresh livers gave a high recovery of oil. Working on a laboratory scale a recovery of 93 per cent of the total oils was obtained. In order to produce a good grade of cod liver oil from the livers produced by schooner fishermen, who are at sea for periods up to a week, some form of preservation, usually soda ash, is used. When these livers are subse- quently treated for the production of cod liver oil, the oil takes on a taste and odour Which, until the substances causing these odours or flavours are determined, we describe as "alkaline", although an aqueous extract'obtained by shaking the oil with water does not give an alkaline reaction. It. was found that a great deal of the taste and odour could be removed by three or four washings.with hot water. A more efficient method, however, consists in steaming the oil at 100QC. under reduced pressure. Conditions at present recommended are the passing of steam equivalent to 20 gallons, of water through 100 gallons of oil at a pressure not greater than 2 cm. of mercury and a temperature of 100 ° C, "Alkaline" oils treated in this manner have been reported by the, trade to be "exceptionally good" as to colour, taste and odour. Others have reported them to be superior to oil made from perfectly fresh livers. A 60 The destearination of cod liver oil The usual losses suffered by the trade in destearination of cod liver oil are from 20-30 per cent. In order to minimize these losses, experiments have been started along two lines; firstly, the recovery of oil from the stearin itself and secondly, experiments designed to keep the stearin losses in the original pressing as low, as possible. It has been found that by subjecting the stearin from plants of two different companies to gradual increases in pressure up to 400 *pounds per square inch from 45 to 65 per cent of the stearin could be recovered as destearinated oil. By determining the freezing curve of cod liver oil it was noted that when large volumes of oil were slowly frozen (45 gallons of oil were air frozen by placing them in a room at 0 ° C.) that the cooling curve showed an irregularity at a temperature of around 8 ° C. This indicates that most of the stearin might, if given time, crystallize out at this temperature. If so, the crystals should be large and more easily filtered than if the oil Were quickly super-cooled to 0 ° C. An experiment was therefore tried in which the oil was quickly cooled and its filtering rate compared with one whose cooling rate passed slowly through this critical stage,. Little dif- ference in rate of filtration between the two oils was observed. This will be repeated, however, as the rate in both cases was much higher than expected. A1 Experiments were also carried out to determine the effect of length of period of cold storage and on the rate of filtration. These showed that the rate of filtra- tion increased from .38 ml. per square inch per minute on oils chilled for 48 hours at 0 ° C. to 52 ml. per square inch per minute after 17a hours cooling. W. W. Johnston A6 Appsndix No. 18 OBSERV0I0NS ON THE CHANGES OCCURRING IN COD LIVERS DURING STORAGE During the course of investigations on preserva. tives for cod livers certain hitherto unrecorded changes were observed. Fresh cod livers were treated for sixty minutes. with one atmosphere pressure of ethylene oxide gas then stored at 2 5°C. To compare results and to avoid varia- tions in bacterial contamination and free fatty acid, the fresh livers were halved and one-half was gassed while the other was held without treatment. As an index of spoilage free fatty acid determinations were made at various intervals. The livers were . examined cipalitatively for degree of bacterial contamination at the time of sampling for free fatty acid. Typical results are recorded below. Time of storage at 25 ° C. Fresh 24 hours 48 " 96 " Free fatty acid (Calculated as claie) Gassed Control Per cent Per cent 0.30 0,70 1.00 1.54 0.31 2,10 6,01 7.70 • A6 The untreated livers decomposed rapidly and reached a state of liquefaction after twenty-four hours of incubation. This change was the result of rapid bacterial growth and is reflected in the increase in free fatty acid. The gas sterilized livers remained sterile and retained their identity throughout the period of incubation. The free fatty acid did increase at a relatively slow and constant rate in the treated livers . A plot of the data showed that the untreated livers gave a typical logarithmic products-curve which results from bacterial action. The gas sterilized livers on the other hand gaVe a typical curve for enzyme action with tlke. As the Period of incubation increased the oil from the gas treated livers became progressively darker in colour than the oil from the untreated livers. On closer examination the gassed livers showed that more oxihad occurred at jItation would seem that the the surfaces having contact with air. untreated livers were protected from this change through the activity of contaminating organisms, In addition to the use of gaseous ethylene oxide as a liver preservative carbon dioxide ice alone and in combination with acetone, ether, chloroform and pyridine were tested, In general, the results were in agreement with those reported above with the exception that the ethylene oxide gas treatment was markedly more effective in rendering and maintainig the livers sterile, A64 From these results it is evident that the development of free fatty acid in cod fish liver must be attributed in the main to the activities of contaminating bacteria. While the development of free fatty acid as a result of enzymic activity occurs at a much slower rate it is of commercial importance to the fish oil industry. A satisfactory preservative for fish livers must prevent the growth of all bacteria and at the saine time prevent or delay the action of the liver enzymes. W. W. Johnston A. J. Wood A65 Appendix No. 19 VITAMINS IN LIVER OILS As explained in Appendix 15 to the Annual Report of the Atlantic Fisheries Experimental Station for 1940 a systematic investigation of the vitamin potency of the fish oils of Nova Scotia was begun shortly after the outbreak of war. This investigation was undertaken in co-operation with the Department of Pensions and National Health, that body determining the vitamin D values of te oil, and the Station determining the vitamin A values. Since that time, this w ork has been completely turned over to the Department of Pensions and National Health, and our work now is confined to seeing that the liver samples reach that Department in good condition. Since compiling the last Annual Report however certain values have been obtained on the vitamin content of the liver oils of some fish of the cod species. These are shown in the accompanying table. The term viscera as used in the following t able does not include gonads or stomachs as oil from these organs shows only a low vitamin concentration. The vitamin A values shown were done with the antimony trichloride reagent using an Eyelyn colorimeter, W. W. Johnston f FISH No. of samples Where caught Percentage livers Percentage viscera in fish in fish Avge. Min; Max. Min. Max. Avge. Date of capture Cod 51 Terence Bay Jan. 18, 1941 .79 5.70 Haddock 50 Terence Bay Jan. 18, 1941 2.42 9.5 3 Hake 14 Devil's Is. Nov. 18, 1940 1.61 July 24, 1940 July 31, 1940 Cod 8 Cod 31 Devil's Is. Devil's Is. 2.78 2.13 6.26 3.67 5.06 4.22 8.62 6.12 7.75 5.31 1.61 3.72 2.41 1.51 4.53 2,94 4.18 5.44 4.69 1.35 4.98 3.29 2.70 6.87 3.97 • \ • FISH Percentage oil in livers Percentage oil in viscera L !value of value of visceral oil L liver oil Avge. Min. Max: Avge. Min. 3.23 .22 16.1 1.82 1.1 41.4 15.4 1.14 15.7 4.2 9.1 141,0 53.5 5.6 30.9 13.6 58.5 10.6 Min. Max. 50.9 1.36 9.7 69.5 66.4 0.086 3.38 4.64 .098 1.1 43.4 69.0 60. 3 1.49 2.76 1.96 . .68 5.0 2.01 Cod 12.3 66.4 42.0 1.48 4.93 2.48 .65 4.2 1.29 Cod 16.1 77.2 51.0 1.31 4.97 3.07 .15 2.5 Min. Max. .Avge. Cod 12.4 74.5 Haddock 28.5 ake .337 .685 .85 Max. Avge. SECTION V SMOKED FISH A67 Appendix No, 20 FISH SMOKING In response to several requests for information on the construction of a small smoke-house, Type B smoke-house pamphlets were distributed, One request of particular interest required a house of special construction to permit its ready transportation from place to place . This house, similar in design to Type B smoke-house was built in Halifax and placrd in operation at West Dublin. The first trials with kippers showed that smoking was uneven. A new inlet duct was installed and air delivery to the house increased to 600 C.F.M. A traverse of the house with a hot wire anemometer gave air velocity readings ranging between 40 and 8 0 feet per minute. A trial run with 200 pounds of split salted herring indicated that part of one tier in the centre of the house was only lightly smoked. Con- sequently fish can not be hung in about 15 per cent of the rack space of the house, A Type B smoke-house which has been in operation for over three years was examined . order of 40-60 ft,/min, Air velocities were of the A 6S In the opinion of the athors more uniform and opitker smoking may be obtained by the positive air flow method than by the injector type of flow as is used in the Type B smoke-house. Plans are being made to develop a more satisfactory type of house along these lines of investigation. E. P, Linton A, L. Wood PUBLICATIONS The following papers have been published or subranted for publication during 1941. Collins, V. K. Co --11ns, Dyer, W. Je "Studies of Fish Spoilage. VIII. Volatile Acid of Cod Muscle Press Juice". J. Fish, Res, Bd. Can. V. (3), 197-202, 1911, "Studies of Ke, C. C. Kuchel and S. A. Beatty Changes in Buffering Fish Spoilage. IX. Capacity of Cod Muscle Press Juice"., J. Fish, Res. Bd, Can. V. (a), 2,03-210, 1941. Atlantic Progress "Salting by Weight". Report No, 30, 0,9, 1941. Frank, M, and E. Hess "Studies on Salt Fish. Survival IV, of Eberthella typhosa and Escherichia coli on Salt Fish", J. Fish, Res, Bd, Can. V. (3) ; 249-252, 194 1. Frank, M. and Ee Hess "Studies on Salt Fish. Studies V. on Sporendonema epizoum from "dun" Salt Fish". J, Fish, Res, Bd. Can, V. (a), 276-2,86, 1941. Frank ; Me and E, Hess "Süudies on Salt Fish. Halophilic VI. Brown Molds of the genus Sperendonema emend, Cif, at Red,", J. Fish, Ros. Bd. Can, V. (a), 287-292,, 1941. Hess, E. "Dun Salt Fish", Atlantic Progress Report No , 28, 17-19, 1940, Hess, "A Test to Estimate the Keeping Quality of Fresh Fish". Atlantic Progress Report Ne , 30, 10-12, 1941, EQ Hess, E. "Studies on Fish Spoilage. X, A Tost to Estimate the Keeping Quality of Frsh Fish". Submitted to Je Fish, Res, Bd, Can. Hess. E, "Studies on Salt Fish, The Relative VII, Effect of Various Types of Salt on Preservatives". Submitted to J, Fish, Res, Bd. Can. A70 Hess, E. Effect of "Studies on Salt Fish. VIII. of Red H.O.ophilic Environment upon Growth Bacteria". , Submitted to J. Fish. Res. Bd. Can, Hess, E. The Isolation "Studies on Salt Fish.. Ix. of Red Harophilic Bacteria from Sea Water and; the Slime and Intestine of Marine Fish", Submitted to J. Fish.;Res..Bd, can.. Hess, E. and N. E. Gibbons. "Sudies on Salt Fish, X. Control of the Reddening of Salt Fish". mitted to J. Fish. Res, Bd. Can, The Sub- Hess, E. "Shell Pieces in Canned Lobster". "Proper Method of Weighing Lobster Meat", "Brine and Pickle". "Chilled Lobster Moat", Lobster Canning Circulars Nos. 18-al, 1941. Johnston, W. W, "The Amount of Oil Recovered by Pressing the Cooked Liver Residue". Atlantic Progress, Report No. 29, 11-12, 1941, Johnston, W. W. "Vitamin A in Swordfish (Xiphius Gladius) and Atlantic Progress Tuna (Thvnnus Thynnus)". Report No. 29, 17-18, 1941. Johnston, W. W. "The Sun Rotting of Cod Liver Oil". Progress Report No, a9, 19 20, 1941, Atlantic - Johnston, W, W, "Tryptic Enzymes from Certain Commercial Fishes", J. Fish. £tes, Bd. Can. V. (a), 217-226, 1941. Wood, A. J. and G. J. Sigurdsson "Studies in Bacterial Metabolia m The Glucose Metabolism of I, Organisms Isolated from Commercial Fish". Submitted to J. Fish, Ras. Bd. Can, - r SH 223 F593 1941 Atlantic Fisheries Exper... Annual report of the Atlantic Fisheries... c.1 j 12069715 L318329
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