Environment Canada
Environnement Canada
Fisheries
Service des caches
and. Marine Berytte
erdes sciences de la mer
Canada. Fisheries and Marine
Service. Inspection Branch.
TECHNICAL REPORT SERIES
09039397
Protective Qualities of Four
Diffe ent Packaging Materials
For ishery Products
by
AS. Dewar, E.B.
.
Guptilit F.H. Alleri and RI.. Selfridge
Tectsnical Report Series No. MAR/T-75-3
Inspection Branch
Maritimes Region
c't.3),(e
Protective Qualities of Four Different Packaging
Materials for Fishery Products
By
A.B. Dewar, E.B. Guptill, F.H. Allen and R.L. Selfridge
Technical Report Series No.Mar/T-75-3
Inspection Branch
Maritimes Region
Abstract
Lobster meat (Homarus americanus) and herring fillets (Clupea
harengus) were packed and stored in four packaging materials, namely;
1/2 lb. flat (307 x 200.25) tin plate can (tin can), aluminum foil
laminate pouch (construction from outside to inside: white lacquer/0.012
mm polyester/adhesive/0.007 mm aluminum foil/adhesive/0.07 mm modified
high density polyethylene), poly bag (3.00 mils polyethylene/adhesive/1.00
mil nylon) and waxed cardboard carton, to determine the protection provided by these packaging materials.
Lobster meat selected as a low fat (ay. 1.5%) fishery product,
was packaged, frozen and stored at -18°F for 24 months in the packaging
materials mentioned above. In addition, lobster meat was heat processed
in the 1/2 lb. flat tin can and the aluminum foil laminate pouch and
stored at room temperature for 24 months. Herring fillets, selected as
a high fat (ay. 16%) fishery product, were also packaged in the four
materials used in this study, and stored at -18°F for 24 months. Taste
panel and organoleptic examinations were carried out on samples from the
10 groups at 0, 6, 12, 18 and 24 months storage. Results show that heat
processed lobster meat packed in the tin can and the aluminum foil laminate
pouch, had a storage life of 18 months. Frozen lobster meat in the tin
can had a storage life of over 24 months, 23 months in the aluminum foil
laminate pouch, 18 months in the poly bag and 5 months in the waxed cardboard carton. Frozen herring fillets had a storage life of over 24 months
in the tin can, 23 months in the aluminum foil laminate pouch, 19 months
in the poly bag and 8 months in the waxed cardboard carton.
-2 -
Introduction
Over the years, many changes have come about in the field of
food packaging. The changes were particularly rapid in the last few
years. As pointed out by Norman and Rees (1972) development for many
years was concentrated on improvements of the manufacturing process,
handling techniques in the cannery and in the modifications of materials
to maintain its cost at a reasonable level. Today, consumers demand
more convenient, more aesthetic packaging. This produced imaginative
development in the field of food packaging.
In recent years, flexible material was introduced for the
packaging and protection of foods. Refrigerated or frozen foods,
dehydrated, high-sugar and high acid-content products were the first
to be protected by this material. While flexible packaging has its
advantages and disadvantages, there is still a definite need for a
flexible packaging material or flex can that would be suitable for the
containment of heat preserved products. Davis et al (1972) defines this
type of container as a biologically commercial sterile food container
in which the food product, after being sealed in, is sterilized at
temperatures in excess of 212°F (generally, the process temperature is
between 230-250°F). Most foods with a pH above 4.5, require this type
of process.
3
Davis et al (1972) list some of the advantages of the flexible
container or retort pouch as follows:
1. Improved product quality, flavour, colour and texture due to shorter
process time.
2. The product does not require refrigeration.
3. The container is light in weight, compact (more food, less liquid),
and requires less storage space than a can.
4. A wider selection of portion packs can be offered since it is
relatively easy to change package size.
5. Less cooking time required - food can be heated to serving temperature
in 3-5 minutes.
6. The container is easy to open.
7. It is easy to dispose of.
However, it must be pointed out that the retort pouch has
some disadvantages too. Filling and sealing procedures require special
attention. Contamination of seal surfaces with water or fat seriously
reduce the seal strength. During heat processing, superimposed air is
required to reduce the strain on the seams, since seal strength is
reduced considerably at processing temperatures in the range of 230-250°F.
The retort pouch must be vacuum packed to remove headspace
gas prior to closure, so that the internal pouch pressure developed during
retorting will be kept to a minimum. Otherwise, the seals have a tendency
to rupture even if superimposed air pressure is applied during retorting.
4
Adequate and uniform water circulation throughout the load must be
provided at all times. Handling and even packing of flexible packages
also require special consideration.
Generally, the protection provided by flexible containers
depends upon the durability of the packaging material (e.g. its
tensile strength and its ability to withstand initial tear and scratching and to withstand heavy impack and prolonged flexing); its chemical
resistance and its gas barrier properties.
The product and package must be compatible. Changes in the
product caused by a packaging material may render it unacceptable.
Odours or flavours in food caused by migration of plasticizers from
plastic films or by unevaporated solvents from inks or coating may
taint the product.
Some of the foil laminates are claimed to have good barrier
properties which approaches that of metal cans. To estimate the protective qualities of laminates, two laminates were compared to the tin
plate can used to package fishery products. An aluminum foil laminate
(whose construction from the outside to the inside is as follows:)
white lacquer/0.012 mm polyester/adhesive/0.007 mm aluminum foil/adhesive/0.07 mm modified high density polyethylene) and a poly bag identified as follows: 3.00 mils polyethylene/adhesive/1.00 mil nylon
- total gauge 4.25 mils
- adhesive is polyurethane type
- polyethylene is in low density range,
5
were employed for the packaging of lobster meat and herring fillets.
Lobster meat, with an average fat content of 1.5%, was chosen to
represent a low fat fishery product, while herring fillets, with an
average fat content of 16%, was chosen to represent a relatively high
fat fishery product. The tin plate can was used as the control packaging material. The regular waxed cardboard carton (1 lb.) was also
used for comparison purposes.
Materials and Methods
Live lobster, weighing less than one pound each, were employed
in this study. The lobsters were cooked in fresh water for 12 minutes
at 212°F after which they were cooled with cold, fresh running water.
The meat was extracted from the shells by hand and was washed in cold,
fresh running water, drained and packaged using the materials indicated
below:
Type of Container
No. of Samples
Fill-in Weight
Treatment
Sealing
1/2 lb. flat tin
can (307 x 200.25)
50
6.5 oz
30 ml
8% NaCl
Vacuum
21 in Hg
Aluminum foil
laminate
50
6.5 oz
30 ml
8% NaCl
Vacuum
30 in Hg
Poly bag (laminate)
25
6.5 oz
30 ml
8% NaCl
Vacuum
30 in Hg
Waxed cardboard
carton
25
6.5 oz
30 ml
8% NaCl
No
Vacuum
- 6-
The tin cans (tin plate) were vacuum sealed (vacuum 21 in.
Hg) in a semi-automatic vacuum sealing machine and the two laminates
were sealed with an ACDL vacuum packaging machine (Vacuum 30 in. Hg).
Twenty-five (25) samples from each group were frozen in
a plate freezer, immediately after packing and then stored at -18°F
until examination.
The remaining 25 samples (tin cans) and 25 samples (aluminum
foil laminate) were heat processed and then held at room temperature
(70°F) until examination. The cans were heat-processed for 35 min. at
240°F, then cooled in the retort by means of water and air pressure
(12 psi) until the average temperature of the can contents was approximately 100°F.
The retort-pouches were heat processed under water (held in
position by wire mesh racks) for 30 min. at 240°F. A superimposed
air pressure of 20.3 psi was maintained (10.3 due to the water-steam
temperature and 10 lb. overriding air pressure). Adequate water circulation in the retort was maintained by "bubbling-in" a continuous flow
of air. The containers were water cooled in the retort using superimposed air pressure until the average temperature of the flexible container reached room temperature.
The canned lobster received an F value of 4.0 during pro0
cessing. The heat process for the retort-pouch was calculated to be
an F value of 4.1.
0
-7-
Herring used in this study was caught in gill nets off Three
Fathom Harbour, N.S. After landing at dockside, the fish were immediately placed in styrofoam boxes, iced and transported to the Halifax
Fish Inspection Laboratory.
The average fat content of the herring flesh was 16%.
Prior to packing, the herring were filleted, the fillets
washed in cold running fresh water, drained, then packaged as indicated
below.
No. of Samples
Fill-in Weight
Sealing
1 lb. flat tin can
(404 x 206)
25
15 oz
Vacuum
21 in Hg
Aluminum foil
laminate
25
16 oz
Vacuum
30 in Hg
Poly bag (Laminate)
25
16 oz
Vacuum
30 in Hg
Waxed cardboard
carton
25
12 oz
No Vacuum
Type of Container
The herring samples were sealed, frozen and stored in the same
manner as the frozen lobster meat samples. All the containers were
frozen and held at -18°F.
Organoleptic examinations were carried out by a trained taste
panel on coded samples after 0, 6, 12, 18 and 24 months storage. A
sample consisted of 5 randomly selected containers.
- 8
The quality of the samples was rated on a 10-0 point scale.
A score of 10 corresponded to normal or the most desirable, and a score of
0 for the least favourable rating. A score of less than 5 indicates reject
quality. The overall quality of a sample was expressed by the lowest score
assigned to either appearance, odour, flavour or texture. The final score
of an assessed characteristic was obtained by averaging the individual scores
of the 5 sample units examined at any given sampling time.
Results and Discussion
Heat Processed Lobster Meat
Figure 1 illustrates the storage life obtained in, the tin can and
the aluminum foil laminate container, at room temperature. The overall
quality of the lobster meat in the retort-pouch was rated slightly lower
than the product in the tin can. The pigment'of the lobster meat had a
tendency to adhere to the foil much more than to the surface of the metal
can. This harms the appearance of the product. The meat in the pouch pack
had slightly more greyish discolouration than in the can pack. The normal
red colour of the claw tips in the tin can had slightly more greenish discolouration than in the pouch pack at the end of the storage period. However, in spite of this, the overall quality of the lobster meat in the cans
was still assessed better than in the pouches. Odours and flavours were
rated lower for the pouch pack at the end of the 2 year storage period.
The drained weight and the pH of the heat processed meat did not
Change significantly during 2 years of storage at ad:dant temperature.
9
Frozen Lobster Meat
Figure 2 illustrates the protection provided by the 4 packaging
materials to samples at -18°F storage. The tin can gave the.best protection followed by the aluminum foil laminate pouch, the poly bag and the
waxed paper carton. The waxed carton afforded little protection to the
lobster meat. The claw meat in the waxed carton had a strong dulce like
odour and flavour due to oxidation of the fatty part of the claw, (the
non straited muscle). Discolouration and freezer burn (dessication) were
also evident after 6 months storage. The tail meat was quite tough and
the texture of the claws was pulpy and granular-like.
The tin can, aluminum foil laminate and poly bag all provided
better protection to the samples than the waxed cardboard carton. The
storage life of samples packaged in the aluminum foil laminate was slightly
shorter than the storage life of samples in the metal cans.
Comparison of Heat Processed and Frozen Lobster Meat
Figure 3 shows the taste panel assessment of heat processed and
frozen lobster meat packed in the various types of containers at the end of
24 months storage. The tin can (A and C) gave the best protection, both for
the heat processed and for the frozen pack. It was closely followed by the
aluminum foil laminate pouch (B and D). The poly bag provided fairly good
protection for the frozen samples.
Frozen Herring Fillets
Figure 4 shows the protection provided by the 4 packaging materials
for the frozen herring fillets over a 24 month period. As in the case of
- 10 lobster (see figure 2), the relative protective properties of the packaging
materials were similar. The tin can provided the best protection to herring
fillets, followed by the aluminum foil laminate, then the poly bag and the
waxed cardboard carton. The low taste panel scored for the waxed carton
points out the lack of protection from oxidation and dessication resulting
in rancidity, discolouration and adverse texture ratings.
The apparent improvement in quality at 18 months storage in
the aluminum foil laminate pouch and the waxed paper carton is considered
attributable to variations in taste panel response and the quality of the
raw material.
Storage Life of Heat Processed and Frozen Samples in the Various Packaging Materials
Figure 5 shows the storage life of samples in the various packaging
materials under two different storage conditions.
Frozen lobster meat in the metal can had a storage life of more than
24 months at -18°F. The storage life in aluminum foil laminate under the
same conditions was 23 months, and in the poly bag, 18 months. Lobster meat
remained of acceptable quality for only 5 months in the waxed paper carton.
Heat processed lobster meat was of acceptable quality for approximately 18 months in the tin can and also in the aluminum foil laminate pouch.
Herring fillets had a storage life of over 24 months in the tin
can, 23 months in the aluminum foil laminate pouch, 19 months in the poly
bag and 8 months in the waxed cardboard carton at -18°F.
Neither the aluminum foil laminate nor the poly bag imparted odours
or flavours to the product.
The aluminum foil laminate showed no adverse affects of heat processing
at 240°F. This material did not deteriorate during storage, i.e., it
didn't peel or separate, and no pin holes were detected even at the end
of 24 months storage at room temperature or at -18°F.
Neither delamination nor cracking was observed in the poly
bags after 2 years storage at -18°F.
Conclusion
The tin plate can provided the best protection in both the
heat processed and in the frozen products studied. Pouches made from
aluminum foil laminate approached the tin can in their protection
properties. Although the poly bag gave less protection than the metal
can or the aluminum foil laminate, it has the added advantage of being
transparent. Waxed cardboard cartons without a cellophane insert or
waxed ovenwrap give poor protection to the product.
The aluminum foil laminate pack resisted adverse retorting
effects well, but requires special care in sealing, retorting and handling
to ensure the integrity of the seal as well as the container.
Acknowledgements
The authors are indebted to the following persons for their
contribution to this work:
S. Varga, W.E. Anderson, G.G. Sims, M.C. Murray, B. Lauer,
J.B. Myrick, J. Wang and G.E. Mack for participation in taste panels.
The authors are especially indebted to Aldan of Canada Limited
°for providing the aluminum foil laminate for this study, and to Du Pont of
Canada Limited for providing the poly bags.
- 12 -
References
Alder - Nissen, J. 1972. Fully Preserved Goods in Flexible Packages.
Emballage 2, p 12.
Davis, R.B., F.E. Long, and W.F. Robertson. 1972. Engineering Considerations in Retort Processing of Flexible Packages. Food Technology, 26,
No. 8, p 65-68.
Konigsbacher, K.S. 1974. Technology for Shelf Stable Foods. (First of
two parts) Food Product Development, 8, No. 7, p 18-25.
Konigsbacher, K.S. 1974. Technology for Shelf Stable Foods. (Second of
two parts) Food Product Development, 8, p 28-30.
Norman, G.F. and J.A.G. Rees. 1972. New Era for Metal Containers.
Food Manufacture, 47, No. 9, p 27-31.
Sacharow, S. 1972. "Testing Packaging Films". Food Product Development 6,
No. 4, p 40-42.
Turtle, B.I. and M.G. Alderson. 1971. Sterilisable Flexible Packaging.
Food Manufacture, 46, No. 9, p 23-37.
Fig 1: The quality of heat processed lobster meat packed in tin plate
cans and aluminum foil laminate.
10-
A
B
Legend:
A-Tin plate can
B -Aluminum foil
laminate pouch
2
4
6
8
10
Storage time (months)
12
14
16
18
20
22
24
Fig 2: The quality of frozen lobster meat packed in four different packaging
materials during storage at -18°F.
10-
Legend:
A-Tin plate can
2-
B - Aluminum Laminate Pouch
C -Pay Bag
1-
D -Waxed Cardboard Carton
0
2
4
6
8
10
12
14
16
18
Storage Time (months)
20
22
24
Fig 3: The quality of heat processed and frozen lobster meat
packed in different packaging materials at the end of
24 months storage.
109—
8—
Overall Quality Score
7
6—
5
4—
3—
A
2
B
C
D
E
1—
0
Heat processed
Frozen (-18°F)
Legend:
A - Tin plate can
B - Aluminum foil laminate
C - Tin plate can
D - Aluminum foil laminate
E - Poly bag
F - Waxed cardboard carton
F
Fig 4: The quality of frozen herring fillets packed in four different
packaging materials during storage at -18°F.
Overall Quality Score
10
Legend:
A - Tin plate can
- Aluminum foil laminate pouch
C - Poly bag
D - Waxed cardboard carton
0
2
4
6
8
10
12
14
16
Storage Time (months)
18
20
22
24
Fig 5
LOBSTER MEAT
Storage life in months
24-
Legend:
A - Tin plate can (Frozen)
B - Aluminum foil laminate (Frozen)
C - Poly bag (Frozen)
D - Waxed Cardboard Carton (Frozen)
E - Tin plate can (Heat processed)
0(
A
B
C
E
D
F
Jl
F - Aluminum foil laminate
(Heat processed)
Frozen (-18°F) Heat processed
FROZEN HERRING FILLETS
Storage life in months
241)
Legend:
18-
v
A - Tin plate can
B - Aluminum foil laminate
C- Poly bag
D - Waxed Cardboard Carton