APTEFF, 45, 1-283 (2014)
DOI: 10.2298/APT1445055M
UDC: 637.1/.3:[66-97:636.085-7
BIBLID: 1450-7188 (2014) 45, 55-66
Original scientific paper
STORAGE TEMPERATURE: A FACTOR OF SHELF LIFE OF DAIRY
PRODUCTS
Nurgin R. Memiši1, Slavica M. Vesković Moračanin2, Marija M. Škrinjar3,
Mirela D. Iličić3, Mira Đ. Ač3
1
AD Mlekara – Subotica, Tolminska 10, 24000 Subotica, Serbia
Institute for Meat Hygiene and Technology, Kaćanskog 13, 11000 Belgrade, Serbia,
3
University of Novi Sad, Faculty of Technology Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia,
2
An experiment was designed to monitor the durability of certain dairy products stored
at proper temperatures (8oC) and elevated temperatures (14oC) within their shelf life.
Samples of fermented milk products were tested during 25 days, samples of cheese spread
products over 80 days, while soft white cheese samples were analyzed during a storage
period of 100 days. In the defined study periods, depending on the type of product, pH
and aw value of the product, as well as sensory analysis (odor, taste, color and consistency), along with microbiological safety, were investigated. The investigations were
performed in accordance with national legislation. The results indicate that the products
stored at 14oC showed significant acidity (lower pH value), changed sensory properties,
and had an increased number of aerobic bacteria.
KEY WORDS: milk products, shelf life, storage temperature, quality
INTRODUCTION
It is well known that, depending of numerous internal and external factors, the growth
of microorganisms during the storage of dairy products results in their sensory changes,
i.e. spoilage. This is due to the fact that under the inadequate storage conditions, nutrients
in the milk products are a good medium for the growth and development of individual
groups of microorganisms. The diverse range of dairy products found on the market today is a result of the knowledge and experience acquired over the years. However, the
contemporary consumer sets high requirements for the producer, expecting from it to stay
abreast of modern trends, related to both high quality and product safety.
In other words, the consumer’s primary requirement is that during the estimated time
of storage the food remains safe, i.e. without adverse changes (1). The length of shelf life
of milk products is primarily influenced by the number and type of microorganisms present in the raw milk as the primary raw material, state of packaging material, hygienic
and sanitary conditions during the production cycle (washing and disinfection of the
* Corresponding author: Nurgin R. Memiši, AD Mlekara – Subotica, Tolminska 10, 24000 Subotica, Serbia,
e-mail: [email protected]
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Original scientific paper
equipment, pasteurization temperature regimes), as well as by the storage temperature of
the final product.
In most cases, the microorganisms that cause the spoiling of milk and dairy products
(2,3) reduce to some extent their quality, which results in significant economic losses.
The reduced quality results from different chemical and biochemical bonds which cause
change of appearance, smell, texture, taste, and aroma of the products. The appearance of
those bonds is conditioned by metabolic degradation of some components of the product,
by microorganisms causing the spoilage or by their enzymes (4).
Yogurt is known as a good nutritive medium, with a relatively low pH, favorable for
the development of acidophilic microorganisms, as opposed to cheese which is less acidic
and contains less water, as well as added salts, resulting in low aw value, thus partially limiting the growth and multiplication of certain microorganisms. In addition, with its firm
consistency, cheese limits in some way the mobility of the microorganisms that cause
spoilage (5).
Fresh cheeses are unripened cheeses, which are manufactured by the coagulation of
milk, cream or whey using acid, a combination of acid and rennet or a combination of
acid and heat. Many processing factors (milk pre-heat treatment, rate and temperature of
acidification, level of gel-forming protein, pH) influence the coagulum structure and
hence the rheological and physico-chemical stability and nutritive value of the fresh
cheese (6,7). Starter culture plays an important role in the process of coagulation and
governs the flavor, body and texture of the cheese, and helps to suppress the growth of
pathogenic and spoilage bacteria (8,9).
During the past 30 years, the use of ultrafiltered (UF) milk for cheese making has
attracted considerable attention throughout the world (8). Cheeses being successfully
made from cow’s milk by the UF process, on an industrial scale, include Camambert,
Feta and Mozzarela cheeses, as well as many varieties of soft cheeses from cow’s milk
(Cottage cheese, Quarg cheese, Cream cheese, Domiati cheese, etc.). Generally, the advantages of the cheeses made by UF process are higher pH, increased cheese yields, higher protein, fat and total solids content (8). The investigated fresh soft white cheese
(Domiaty type) made from goat milk using UF process showed 85% reduction in total
process time, as well as salt, starter culture, rennet and calcium chloride.
The aim of this study was to investigate the effect of the storage temperature on the
microbiological characteristics (lactobacilli, number of aerobic bacteria, CFU/g), physicochemical characteristics (pH value, aw), and sensory properties of the fermented milk
products, cheese spreads and soft white cheese during their storage.
EXPERIMENTAL
The experiment was designed to monitor the durability of certain dairy products
(fermented milk products, cheese spreads, and soft white cheese) stored at proper temperatures (8oC) and elevated temperatures (14oC), within their shelf life. Samples were
taken from each group of products, in original packaging units, immediately after production, and kept at predefined temperatures in the refrigerated chambers with automatic
temperature control (8 and 14oC). Microbiological, physico-chemical and sensory inves56
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DOI: 10.2298/APT1445055M
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Original scientific paper
tigations were performed according to a plan which included testing of the finished products immediately after manufacture, testing midway through the declared shelf life, and
at the end of the shelf life.
Milk products and technological production procedure
Fermented milk products
Raw milk standardized to 2.8% milk fat, was pasteurized and homogenized (95oC, 6
sec., P=150 bar). After cooling to the optimal temperature (38oC), homogenized milk was
inoculated with yogurt culture -Bulk Set 442 – contains Lactobacillus delbruecki subsp.
bulgaricus and Streptococcus thermophilus, (Danisco-Denmark). The fermentation process was considered completed when the fermented milk product has achieved a specific
pH (4.65), then cooled (to 20oC), and the finished product was filled and packaged into
PET packaging in a closed manufacturing system with hepa filters and adequate overpressure.
Cheese spreads
Cheese spreads are products obtained from fermented cream. The cream containing
approximately 21% milk fat was mixed with skimmed milk powder. After the heat treatment (105oC) and cooling to the optimal temperature (37oC), it was inoculated with a butyric culture - Proba 505 - contains Lactococcus lactis subsp. lactis, Lc. lactis subsp.
cremoris, Lc. lactis subsp. lactis biovar. diacetylactis, Leuconostoc mesenteroides subsp.
Cremoris, (Danisco-Denmark). The fermentation process was interrupted by cooling,
when the optimal pH (4.6) for the product was achieved, The formed byproduct was
mixed with butter and stabilizer according to the manufacturer’s specification, and then
heat treated in a thermizer to the optimal temperature (78-82oC). The hot product was filled into plastic containers and hermetically sealed with Al lids.
Soft white cheese, 45% milk fat in dry matter
Soft white cheese is a product obtained from pasteurized cow milk standardized to
3.75% milk fat. After ultrafiltration, the obtained retentate was pasteurized at a temperature above 78oC, cooled in a system of coolers, and then transferred to a duplicator,
where it was stored. The cheese culture - FRC 75- contains Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, Streptococcus thermophilus and Lactobacillus
delbrueckii subsp. Bulgaricus, (Danisco-Denmark). and commercial rennet were then simultaneously added to the semi-finished product. In a closed industrial packaging system
with inbuilt hepa filters, the product was filled into plastic containers of various volumes
(250 g, 500 g and 1 kg), and then transported to the fermentation chamber. After the fermentation time of 20 min, a semipermeable membrane was placed on the surface of the
product, over which a required quantity of salt (2%) was added, according to the manufacturer’s specification.
After this, the container was closed with an Al lid, and hermetic sealing was secured
by thermal sealing, after which another protective lid was placed on the top. Then, the
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closed product was placed on a plastic palette and transferred to a chamber for additional
(final) fermentation (10 h, 30-32oC), until the desired consistency and final pH (4.85)
were achieved. After the completion of the fermentation, the product was intensively
cooled in the cooler to a temperature of up to 8oC.
Microbiological analysis
Microbiological examination of the dairy products was performed in accordance with
the Regulations of General and Special Conditions of Food Hygiene at any Stage of Production, Processing and Trade (10), according to the Regulation (EC) No 2073/2005 (11),
as well as with the elements of self-control prescribed in the HACCP plans. Briefly, 25 g
of each sample were transferred to a sterile stomacher bag and 225 mL of saline-peptone
water was added and mixed for 30 seconds in the stomacher. Further decimal dilutions
with the same diluents were made, and the following analyses were performed on duplicate agar plates: total viable count of microorganisms on Plate Count Agar (ISO
4833/2003) (12); mesophilic lactic acid bacteria (LAB) on a double layered MRS agar
and incubated at 30oC for 48 h (ISO 15214/1998) (13); Escherichia coli on Violet Red
Bile (VRB) agar (ISO 16649-1/2009) (14); Staphylococcus aureus on Baird Parker medium with added egg yolk tellurite emulsion (ISO 6888-1/1999) (15); yeast and moulds on
Sabouraud-4% Maltose agar containing 2% of chloramphenicol. The dishes were incubated at 25oC during 5 days (16). The detection and enumeration of Listeria monocytogenes
and Salmonella spp were carried out following the procedure ISO 11290-1, 2/2004 and
ISO 6579/2002, respectively (17, 18).
Physico-chemical analysis
The physico-chemical investigation included the determination of the pH values (pH
meter, MA-5730, No 35 398 PAT, Iskra) and water activity (aw), using a hygrometer
(Wert-Messer, Durotherm), at a constant temperature of 25ºC.
Sensory analysis
The sensory investigations were performed at three stages of production: finished product immediately after manufacture, testing midway through the declared shelf life, and
at the end of the shelf life.
A group of six panelists was formed from the pool of trained panel members for evaluating sensory characteristics. Sensory characteristics of odor, taste, color and consistency were evaluated according to hedonic scale 1 to 3 (3 - “exceptionally acceptable”, 2“acceptable”, 1- “unacceptable”). The total sensory score for excellent milk products was
set as 12.
Statistical analyses
Statistical analysis was used to study the influence of chemical composition and sensory evaluation by single-factor analysis of variance (ANOVA). The differences between
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individual means were tested. Significant differences were considered for P<0.05, P<0.01
and P<0.001. Calculations were performed using Statistics for Windows 5.1 Stat Soft
(Stat Soft 1996) (19).
RESULTS AND DISCUSSION
The results of physico-chemical investigations of milk products during different storage periods are presented in Table 1. It can be seen that the pH value decreased slightly
with storage time at 8oC. On the other hand, the pH value decreased significantly (P<
0.01) with storage time at 14oC. The pH of fermented milk products after 13 days of storage showed the lowest value 3.96±0.04 and after 25 days of storage it was 4.01±0.017.
Cheese spread samples were analyzed for the pH and water activity. No significant
(P<0.01) changes of the values of these parameters were recorded throughout the 80 days
of storage period for the cheese spread samples at 8oC. On the other hand, a very little
and non-significant decrease of the pH value and increased water activity value were
recorded after 80 days of storage at 14oC.
Table 1. Results of the physico-chemical testing of the products
during the storage
Type of product
Storage
temperature
Days of testing
Day 1
Fermented milk
products
8oC
14oC
4.42±0.014
4.43±0.035
Day 1
Cheese spreads
8oC
14oC
4.68±0.023
4.71±0.021
8oC
14oC
0.962
0.964
Day 1
Soft white cheese,
45% milk fat in
dry matter
8oC
14oC
4.82±0.015
4.83±0.012
8oC
14oC
0.958
0.959
Day 13
pH value (Ā ±SD)
4.20±0.013
3.96±0.040
Days of testing
Day 40
pH value (Ā ±SD)
4.65±0.010
4.61±0.013
aw value
0.968
0.966
Days of testing
Day 50
pH value (Ā ±SD)
4.73±0.014
4.15±0.010
aw value
0.966
0.977
Day 25
4.26±0.093
4.01±0.017
Day 80
4.66±0.014
4.52±0.007
0.966
0.973
Day 100
4.65±0.018
3.64±0.007
0.968
-
Ā – average value; SD − standard deviation; n = 240
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For the soft white cheese, the pH value decreased gradually from 4.82±0.015 and after 100 days of storage at 8oC, it was 4.65±0.018. It was also seen that during the first 50
days the pH value did not decrease significantly (P<0.05), but at the end of the storage
period (100 days) this decrease was-significant (P<0.01). For the soft white cheese samples stored at 8oC, the aw value did not change (approximately 0.96) significantly, while
for the same samples stored at a higher temperature, the aw value increased to 0.977 after
50 days of storage and at the end of shelf life it was not measured because the samples
showed pronounced signs of spoilage (changed consistency, structure, and sensory properties). The microbiological test results showed that all the tested dairy products samples
did not contain L. monocytogenes, E. coli, Salmonella spp, Staphylococcus aureus, and/or
yeasts and molds. The finished products, as well as all the stored dairy products were safe
for consumption.
Table 2. Results of microbiological testing of the products during the storage
Type of product
Fermented milk
products
Cheese spreads
Soft white cheese,
45% milk fat in
dry matter
Storage
temperature
Day of testing
Day 1
Day 13
Day 25
Total number of LAB, CFU/mL (Ā±SD)
8°C
3.4×108 a
1.7×108 a
2.8×107 a
°
8a
8b
14 C
3.4×10
1.4×10
2.3×107 b
Days of testing
Day 1
Day 40
Day 80
Total aerobic microbial count, CFU/g (Ā±SD)
8°C
<10 a
θa
θa
°
b
b
14 C
θ
60
200b
Days of testing
Day 1
Day 50
Day 100
Total aerobic microbial count , CFU/g (Ā±SD)
8°C
θ
θa
θa
°
b
14 C
θ
150
6x 103 b
CFU  colony forming units; LAB − lactic acid bacteria; detection limit 10 cfu/g
Ā – average value; SD − standard deviation; n = 240
a,b
Means within the same column with different superscripts differ significantly (p<0.05)
The population of lactobacilli in the fermented milk products was characteristic for
this type of product. However, no significant changes in lactic acid bacteria count were
observed throughout the storage period at both investigated temperatures (Table 2). The
total aerobic microbial count was below detection limit throughout the storage period at
8oC for both spread cheese and soft white cheese. On the other hand, a gradual increase
of the aerobic microbial count was observed at elevated temperature for both products.
The aerobic microbial count in soft white cheese was 6.0×103 CFU/g after 100 days of
storage at 14oC (P<0.05).
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Table 3. Results of sensory analysis of the milk products during the storage
Type of product
Fermented
milk
products
Consistency
(Ā±SD)
Odor
(Ā±SD)
Taste
(Ā±SD)
Appearance
(Ā±SD)
Total
°
14 C
Consistency
(Ā±SD)
Odor
(Ā±SD)
Cheese
spreads
Taste
(Ā±SD)
Appearance
(Ā±SD)
Total
Consistency
(Ā±SD)
Soft white
cheese,
45% milk
fat in dry
matter
Odor
(Ā±SD)
Taste
(Ā±SD)
Appearance
(Ā±SD)
Total
Storage
temperature
8°C
14°C
8°C
14°C
8°C
14°C
8°C
14°C
8°C
Day 1
3.0±0,00NS
3.0±0,00
3.0±0.00NS
3.0±0.00
3.0±0.00NS
2.93±0.25
3.0±0.00NS
3.0±0.00
Day of testing
Day 13
3.0±0.00b
2.06±0.70a
2.86±0.35b
1.93±0.70a
3.0±0.00b
2.0±0.37a
3.0±0.00b
2.2±0.67a
Day 25
2.93±0.25b
1.66±0.61a
2.93±0.25b
1.86±0.74a
2.86±0.35b
1.73±0.59a
3.0±0.00b
2.00±0.37a
12.0±0.00NS
11.86±0.07b
11.72±0.05b
7.25±0.15a
8°C
14°C
8°C
14°C
8°C
14°C
8°C
14°C
8°C
Day 1
3.0±0,00NS
3.0±0,00
3.0±0.00NS
3.0±0.00
3.0±0.00NS
3.0±0.00
3.0±0.00NS
3.0±0.00
8.19±0.11
Day of testing
Day 40
3.0±0.00b
1.46±0.64a
3.0±0.00b
1.66±0.62a
2.93±0.25b
1.4±0.50a
3.0±0.00b
1.86±0.74a
12.0±0.00NS
11.93±0.035b
11.69±0.09b
14°C
12.0±0.00
4.92±0.16a
Day 1
3.0±0,00NS
3.0±0,00
3.0±0.00NS
3.0±0.00
3.0±0.00NS
3.0±0.00
3.0±0.00NS
3.0±0.00
6.38±0.20a
Day of testing
Day 40
2.83±0.41b
1.0±0.00a
3.0±0.00b
1.0±0.0a
2.86±0.35b
1.0±0.0a
2.93±0.25b
1.16±0.41a
Day 80
2.8±0.56b
1.0±0.00a
3.0±0.00b
1.0±0.00a
2.80±0.41b
1.0±0.00a
2.73±0.45b
1.0±0.00a
12.0±0.00NS
12.0±0.00
11.62±0.07b
4.16±0.008a
11.33±0.12b
4.0±0.00a
8°C
14°C
8°C
14°C
8°C
14°C
8°C
14°C
8°C
14°C
11.93±0.035
a
Day 80
2.83±0.41b
1.26±0.45a
3.0±0.00b
1.33±0.48a
2.86±0.35b
1.0±0.00a
3.0±0.00b
1.33±0.48a
Ā - average value; SD − standard deviation
- no significant difference (p>0.05)
a,b
- Means within the same column with different superscripts differ significantly (p<0.05)
NS
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On the day 1 of the postproduction, all investigated products (Table 3) had uniform
sensory properties, characteristic for each type of product (P>0.05). At the storage temperatures of up to 14oC, the most pronounced changes were found for the soft white cheeses, as well as cheese spreads. In the soft white cheeses, already midway through the
shelf life (day 50) there were considerable changes (overall grade 4.16±0.008), of all sensory characteristics (onset of bitterness, changed structure, unpleasant odor), and the observed differences were statistically significant (P<0.05). The effect of various storage
temperatures is directly linked to the lipolytic and proteolytic processes taking place in
the product itself, with the intensity directly dependent on the external temperature. This
is corroborated by the results of (20), stating that the intensity of proteolysis was more
pronounced in the samples of Mozzarella cheese stored at higher temperatures (the experiment was done at 4 and 12oC). The mini cheeses stored at 18oC for 12 weeks had altered sensory properties compared to cheeses stored at 7oC for 24 weeks (21). In the investigation of Kamleh et al. (22) it was found that the nominal shelf life of Halloumi cheese
stored at 5oC was 79.6 days and dropped to 37.8 days at 15oC, suggesting the conformity
of the quality changes in the product to the Q10 value of 2. However, the dramatic drop
in the shelf life of the product stored at 25oC to 2.6 days was caused by detrimental changes in the cheese appearance.
In addition, the same regularity for the change of the sensory characteristics during
the storage period was also noticed in the group of cheese spreads. Already midway
through the shelf life (day 40), a rancid taste and changed structure appeared, with statistically significant differences (P<0.05). In the fermented products stored at 14oC, a
mild increase of the acidity, as well as of the intensity of syneresis were observed, with
statistical differences between product samples stored at different temperatures at the
P<0.05 level.
Hruškar et al., (23) showed that during the storage of probiotic yogurt at the temperatures of 4 and 20oC there was a change of the quality of the stored products, and that the
changes were more pronounced at higher storage temperatures. The decrease in the product quality was linked to the increase in the contents of lactic and citric acids. The investigations of the microbiological processes in butter during the storage period and cooling
temperatures (24) indicated that the increase of the total microorganism and lipolytic
bacteria counts was intensive after the day 15, and that on the day 30 at 4oC the counts increased by up to 10 times. The same author stated that the change in the lipolytic bacteria
count was directly proportionate to the increase in the total microorganism count.
In a study of the effect of various storage temperatures (-12, 2, 8 and 12oC), as well as
the presence of salt on the microbiological changes in five different types of thermo-processed products (25), it was stated that lower storage temperatures and the presence of
salt had a significant effect on reducing the total number of microorganisms, coliform
bacteria and yeasts, compared to their counts found in the products stored at higher temperatures.
The UHT milk samples, taken in the spring and fall from five different dairies distributed in different regions of France (north, north-west, south-west and central France),
were stored at various temperatures (4, 20 and 40oC), and analyzed after 21, 42, 62, 90,
110 and 180 days, and it was established that higher temperatures (40oC) had a pronounced effect on the pH decrease and increase in non-casein (26). The temperature of storage
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markedly influenced the time of gelation of UHT-sterilized milk. In general, gelation
occurs more readily at room temperatures (20 to 25oC) than at low (4oC) and high (35 to
40oC) temperatures (27).
Burdova et al. (28) have demonstrated that the storage temperature of 10oC reduces
the shelf life of pasteurized milk to one third in comparison with the storage at 4oC. The
average shelf life of the full cream pasteurized milk reached 31 days at 4oC, the average
shelf life of skimmed pasteurized milk was 32.57 days. At 10oC, the average shelf life
was 11 days for the whole and 10.71 days for skimmed pasteurized milk. The evaluation
of proteolytic and lipolytic enzyme activities produced by psychrotrophic microorganisms at different storage temperature showed an increased activity of the psychrotrophic
microorganisms after 2 - 3 d at 10oC. The storage at 4oC did not allow the production of
comparable amounts of these enzymes for a three times longer interval.
CONCLUSIONS
Results of this research enable the following conclusions:
The investigated dairy products: fermented milk products, cheese spreads, and soft
white cheese, stored at 8oC showed no significant pH decrease, as opposed to the products stored at higher temperature (14oC). On the other hand, the established aw values for
cheese spreads and UF cheeses showed no variation during the shelf life. The test results
for sensory properties of the fermented milk products stored at 14oC demonstrated a tendency toward the increase in the acidity during the investigation period, and for the
cheese spread samples a rancid taste was also established. For the cheese samples stored
at 14oC, in the mid of storage period (day 50), a bitter taste, altered structure, as well as a
certain unpleasant odor, were established, with a significantly reduced pH.
The results for the microbiological status showed that during the shelf life, the investigated products were microbiologically adequate. No presence of pathogenic microorganisms was established. On the other hand, elevated storage temperatures caused an increase in the total bacteria count, mainly accompanied by a change of sensory properties,
as well as by a decrease in the pH value.
Acknowledgement
The results presented in this paper are part of Project III, No 46009: “Improvement
and development of hygienic and technological procedures in production of foodstuffs of
animal origin with the aim of producing high-quality and safe products competitive on
the global market” funded by the Ministry of Education, Science and Technological
Development of the Republic of Serbia.
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Original scientific paper
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TЕМПЕРАТУРА СКЛАДИШТЕЊА: ФАКТОР РОКА ТРАЈАЊА МЛЕЧНИХ
ПРОИЗВОДА
Нургин Р. Мемиши1, Славица M. Весковић Морачанин2, Mарија М. Шкрињар3,
Mирела Д. Иличић3 и Мира Ђ. Ач3
1
AД Млекара – Суботица, Tолминска 10, 24000 Суботица, Србија
Институт за хигијену и технологију меса, Качанског 13, 11000 Београд, Србија,
3
Универзитет у Новом Саду, Технолошки факултет, Булевар цара Лазара 1, 21000 Нови Сад, Србија.
2
У оквиру ових истраживања праћена је одрживост појединих група млечних
производа, током њиховог рока трајања, складиштених како на адекватним температурама чувања (8oC) такође, паралелно и на повишеним температурама скла65
APTEFF, 45, 1-283 (2014)
DOI: 10.2298/APT1445055M
UDC: 637.1/.3:[66-97:636.085-7
BIBLID: 1450-7188 (2014) 45, 55-66
Original scientific paper
диштења (на 14oC). Након завршетка производње из сваке производне шарже производа код којих је праћена њихова одрживост, током рока трајања на различитим
температурама чувања, узимани су узорци у оригиналним амбалажним паковањима
који су смештени у расхладне уређаје са подешеним температурама чувања и складиштења (8 и 14oC).
Узорци ферментисаних млечних производа су анализирани током 25 дана, сирних намаза током 80 дана, док су узорци меких белих сирева анализирани током
периода складиштења од 100 дана. Планом предвиђених контрола (почетак, средина и истек рока трајања), у зависности од врсте производа, код узорака су вршена
физичко-хемијска испитивања (pH вредност и aw воде код сирева), затим сензорна
оцена (мирис, укус, боја и коензистенција) и микробиолошка контрола. Сва испитивања су урађена у складу са законском регулативом. На основу резултата ових
испитивања констатовано је да је чувањем производа на неадекватним температурама складиштења (14oC) дошло до повећања укупног броја аеробних бактерија,
промене сензорних својстава производа као и смањења њихове pH вредности
(повећања киселости).
Кључне речи: производи од млека, рок трајања, температуре чувања, квалитет
Received: 5 May 2014.
Accepted: 8 September 2014.
66