scholarly journals Qualitative changes in selected dairy products during their shelf life

2020 ◽  
Vol 76 (09) ◽  
pp. 6444-2020
Author(s):  
JOLANTA KRÓL ◽  
ANETA KARASIŃSKA ◽  
ANETA BRODZIAK ◽  
MAGDALENA STOBIECKA ◽  
JOANNA BARŁOWSKA

The aim of the study was to assess changes in qualitative characteristics of selected dairy products that occur during their shelf life. The research covered 2% pasteurized drinking milk, 18% cream and semi-fat tvarog produced in 3 regional processing plants (A, B and C) and purchased in the local retail network. A total of 186 samples were taken, including 20 samples of each of the above products from plants A and B, and 22 samples of these products from plant C. The following parameters were determined: chemical composition, density, potential acidity (°SH), freezing point, and the number of Enterobacteriaceae in drinking milk; as well as the content of fat, protein and dry matter, potential acidity (°SH), and the number of β-glucuronidasepositive Escherichia coli in cream and tvarogs. The research showed that the dairy products available in the retail network generally met the requirements of Polish standards. Deviations from the standards were found in the fat content of drinking milk and cream compared to that declared by the manufacturer. On both measurement dates, the acidity of the products did not exceed the prescribed limits, which indicates that the quality of the products was maintained during the storage period. The assessment of microbiological quality showed that on both dates the limit of E. coli contamination was exceeded in tvarog samples from dairy C, which indicates an unsatisfactory microbiological quality of the production process in this plant and the need to take corrective actions in the field of production hygiene. Drinking milk and cream, on the other hand, met the legal requirements in terms of process hygiene.


2020 ◽  
Vol 148 ◽  
Author(s):  
J. McLauchlin ◽  
H. Aird ◽  
A. Elliott ◽  
E. Forester ◽  
F. Jørgensen ◽  
...  

Abstract The aim of this study was to review microbiology results from testing >2500 raw drinking milk and dairy products made with unpasteurised milk examined in England between 2013 and 2019. Samples were collected as part of incidents of contamination, investigation of infections or as part of routine monitoring and were tested using standard methods for a range of both pathogens and hygiene indicators. Results from testing samples of raw cow's milk or cheese made from unpasteurised milk for routine monitoring purposes were overall of better microbiological quality than those collected during incident or investigations of infections. Results from routine monitoring were satisfactory for 62% of milks, 82% of cream, 100% of ice-cream, 51% of butter, 63% of kefir and 79% of cheeses, with 5% of all samples being considered potentially hazardous. Analysis of data from cheese demonstrated a significant association between increasing levels of indicator Escherichia coli with elevated levels of coagulase positive staphylococci and decreased probability of isolation of Shiga toxin-producing E. coli. These data highlight the public health risk associated with these products and provide further justification for controls applied to raw drinking milk and dairy products made with unpasteurised milk.





1993 ◽  
Vol 56 (11) ◽  
pp. 983-985 ◽  
Author(s):  
L. C. BLANKENSHIP ◽  
J. S. BAILEY ◽  
N. A. COX ◽  
M. T. MUSGROVE ◽  
M. E. BERRANG ◽  
...  

The microbiological quality of 745 conventionally processed and 745 reprocessed broiler carcasses was determined. Carcasses were taken from the processing line prior to entering the chiller in five commercial processing plants. Each plant was sampled twice during the winter, spring, and summer. Analyses included aerobic bacteria, Enterobacteriaceae, and Escherichia coli counts plus qualitative Salmonella (SAL) prevalence. Differences between overall mean log10 counts for aerobic bacteria, Enterobacteriaceae, and E. coli were not significant. The prevalence of SAL detected on conventionally processed and reprocessed carcasses also was not significantly different. Some variation was observed in microbiological quality of carcasses among processing plants. Although the SAL prevalence appeared to decline from winter to summer replications, no significant trend could be demonstrated. Continuation of the practice of reprocessing carcasses appears justified.



2021 ◽  
Vol 72 (2) ◽  
pp. e401
Author(s):  
Y. Ucar ◽  
Y. Ozogul ◽  
F. Ozogul ◽  
M. Durmus ◽  
A.R. Kösker ◽  
...  

Nisin is produced by Lactococcus lactis subsp. lactis and is also known as an antimicrobial agent especially effective against gram-positive bacteria. It has long been used as a preservative in foods and beverages and is generally regarded as safe (GRAS). In the present work, the effects of different concentrations of nisin (0.2, 0.4 and 0.8%) on the sensory, chemical and microbiological quality and shelf-life of vacuum-packed sea bass (Dicentrarchus labrax) fillets were investigated during chilled (4 ± 2 °C) storage. The sensory points for raw and cooked fillets increased with time during the storage period (p < 0.05). The control group, with scores of 9.08, was rejected by panelists on day 12; whereas nisin-treated groups were rejected on day 14 with scores ranging from 9.00-9.17 score. As a result of chemical analyses, lower values (p < 0.05) were obtained from the nisin groups with low oxidative rancidity. Moreover, nisin inhibited microbial growth, which shows antimicrobial activity. Consequently, it was concluded that the application of nisin (especially 0.8%) preserved the organoleptic quality and extended the shelf-life of sea bass fillets.



2015 ◽  
Vol 78 (1) ◽  
pp. 164-171 ◽  
Author(s):  
MAIKE TAÍS MAZIERO MONTANHINI ◽  
ROBERTO MONTANHINI NETO

This study aimed to determine the effect of temperature and period of postharvest storage on the microbiological quality and shelf life of raw mangrove oysters, Crassostrea brasiliana. A total of 150 dozen oysters were collected directly from the points of extraction or cultivation in southern Brazil, and in the laboratory, they were stored raw at 5, 10, 15, 20, and 25°C for 1, 4, 8, 11, and 15 days. On each of these days, the oysters were subjected to microbiological analyses of aerobic mesophilic count, total coliforms, enterococci, Escherichia coli, Staphylococcus aureus, and Salmonella. None of the tested samples under any storage condition showed contamination levels above those allowed by Brazilian legislation for E. coli, S. aureus, and Salmonella, and there was no change (P &gt; 0.05) in the counts of these microorganisms due to the temperature and/or period of oyster storage. Counts of enterococci and total coliforms showed a tendency to increase (P &lt; 0.05) among the different temperatures tested. Raw mangrove oysters remain in safe microbiological conditions for consumption up to 8 days after harvesting, regardless of temperature, and their shelf life may be extended to 15 days if they are stored at temperatures not exceeding 15°C.



2007 ◽  
Vol 70 (5) ◽  
pp. 1249-1251 ◽  
Author(s):  
SOFRONI EGLEZOS ◽  
BIXING HUANG ◽  
ED STUTTARD

An investigation of the microbiological quality of kangaroo carcasses at two Queensland processing plants was carried out. A total of 836 whole muscle samples were taken, 801 from plant A and 35 from plant B. Samples were analyzed for aerobic bacteria, Escherichia coli, and Salmonella. The mean adjusted aerobic plate count (APC) was 2.8 log CFU/g, and counts at the 90th, 95th, and 99th percentiles were 4.2, 4.9, and 6.4 log CFU/g, respectively. The maximum number of bacteria recovered was 6.5 log CFU/g. E. coli was detected in 13.9% of samples, for which the adjusted mean was 0.7 log CFU/g, and counts at the 90th, 95th, and 99th percentiles were 1.4, 2.0, and 3.0 log CFU/g, respectively. Salmonella was detected in 0.84% of samples. There was no significant relationship (P &lt; 0.05) between season and APC or E. coli count. There was a significant relationship (P &lt; 0.001) between Salmonella prevalence and summer. The microbiological quality of Queensland kangaroo carcasses is similar to that obtained during other excision-based studies of kangaroo, wild boar, and beef carcasses.



Food Research ◽  
2020 ◽  
Vol 4 (6) ◽  
pp. 2256-2264
Author(s):  
E.J. Alice ◽  
M. Amanullah ◽  
M.A. Karim ◽  
M.A. Hossain ◽  
M.T. Islam

Vacuum packaging and modified atmosphere packaging (MAP) are widely applied packaging methods for displaying refrigerated fish and fish products. This study evaluated the biochemical and microbiological quality of sliced goonch fish (Bagarius bagarius) by analysing different parameters under not sealed pack (control), vacuum pack, and MAP-1 (50% CO2 / 50% N2), and MAP-2 (50% CO2 / 50% O2) at three days interval in 15 days of refrigerated storage at 4±1°C. The total volatile base nitrogen (TVB-N), peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) values of the samples in four packaging systems did not cross the acceptable limit in the entire storage time. The total viable count (TVC) progressively increased with time in all packaging systems. However, TVCs were significantly (p<0.05) lower on 9th and 12th storage day in all samples compared to the control sample. Based on the bacterial counts of 7 log CFU/g, the shelflife was determined at about 6, 10, 12, and 9 days for control, vacuum, MAP-1, and MAP2 sample, respectively. All treatments offered satisfactory results during the storage period, except for the control in terms of shelf life. However, MAP-1 with 50% CO2 and 50% N2 demonstrated the promising result for shelf life extension, which can be utilised by the retail superstores for displaying the fishes.



Author(s):  
N.G. Kozyreva ◽  
◽  
I.Yu. Abashin ◽  
L.A. Ivanova ◽  
◽  
...  

This article presents the results of determining the level of perinatal infection of calves with the bovine leukemia virus at the age from birth to colostrum intake and 1-1.5 months after birth when drinking milk from healthy individuals, excluding the alimentary transmission route, with an infection frequency of 5.4% in the surveyed farm. Improvement of molecular diagnostics based on genomic analysis in the scheme of complex antiepizootic/recreational measures for bovine leukemia has been carried out in order to improve the quality of dairy products. As part of the implementation and improvement of the scheme of preventive measures, a positive trend was found, expressed in a tendency to a 3.6-fold decrease in the frequency of detection of BLV infection of young animals. In the course of work, the efficiency of the use of a gene diagnostic test - multiplex PCR-RT – as a tool for the specific prevention of bovine leukemia of calves in the early stages of the disease was shown: the relative diagnostic sensitivity of the PCR-RT technique is at a level not lower than that of the serological method and differs in the side of overestimation by 3.8 times.



Domiati cheese is the most popular brand of cheese ripened in brine in the Middle East in terms of consumed quantities. This study was performed to investigate the impact of the microbiological quality of the used raw materials, the applied traditional processing techniques and ripening period on the quality and safety of the produced cheese. Three hundred random composite samples were collected from three factories at Fayoum Governorate, Egypt. Collected samples represent twenty-five each of: raw milk, table salt, calf rennet, microbial rennet, water, environmental air, whey, fresh cheese, ripened cheese & swabs from: worker hands; cheese molds and utensils; tanks. All samples were examined microbiologically for Standard Plate Count (SPC), coliforms count, Staphylococcus aureus (S. aureus) count, total yeast & mould count, presence of E. coli, Salmonellae and Listeria monocytogenes (L. monocytogenes). The mean value of SPC, coliforms, S. aureus and total yeast & mould counts ranged from (79×102 CFU/m3 for air to 13×108 CFU/g for fresh cheese), (7×102 MPN/ cm2 for tank swabs to 80×106 MPN/ml for raw milk), (9×102 CFU/g for salt to 69×106 CFU/g for fresh cheese) and (2×102 CFU/cm2 for hand swabs to 60×104 CFU/g for fresh cheese), respectively. Whereas, E. coli, Salmonella and L. monocytogenes failed to be detected in all examined samples. There were significant differences in all determined microbiological parameters (p ≤0.05) between fresh and ripened cheese which may be attributed to different adverse conditions such as water activity, pH, salt content and temperature carried out to improve the quality of the product.



2009 ◽  
Vol 72 (4) ◽  
pp. 856-859 ◽  
Author(s):  
HOIKYUNG KIM ◽  
YOUNGJUN LEE ◽  
LARRY R. BEUCHAT ◽  
BONG-JUNE YOON ◽  
JEE-HOON RYU

Sprouted vegetable seeds used as food have been implicated as sources of outbreaks of Salmonella and Escherichia coli O157:H7 infections. We profiled the microbiological quality of sprouts and seeds sold at retail shops in Seoul, Korea. Ninety samples of radish sprouts and mixed sprouts purchased at department stores, supermarkets, and traditional markets and 96 samples of radish, alfalfa, and turnip seeds purchased from online stores were analyzed to determine the number of total aerobic bacteria (TAB) and molds or yeasts (MY) and the incidence of Salmonella, E. coli O157:H7, and Enterobacter sakazakii. Significantly higher numbers of TAB (7.52 log CFU/g) and MY (7.36 log CFU/g) were present on mixed sprouts than on radish sprouts (6.97 and 6.50 CFU/g, respectively). Populations of TAB and MY on the sprouts were not significantly affected by location of purchase. Radish seeds contained TAB and MY populations of 4.08 and 2.42 log CFU/g, respectively, whereas populations of TAB were only 2.54 to 2.84 log CFU/g and populations of MY were 0.82 to 1.69 log CFU/g on alfalfa and turnip seeds, respectively. Salmonella and E. coli O157:H7 were not detected on any of the sprout and seed samples tested. E. sakazakii was not found on seeds, but 13.3% of the mixed sprout samples contained this potentially pathogenic bacterium.



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