The Effect of Storage Temperature on Bacterial Growth and Lipolysis in Raw Milk

Muir, D. D.; Kelly, Morag E.; Phillips, John D.

doi:10.1111/j.1471-0307.1978.tb02137.x

Cited by 32 publications

(10 citation statements)

References 8 publications

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“…However, after 96 h a significant increase ( P < 0.001) was detected (× 49) (this factor of bacterial count increase is the result obtained by dividing the average final count by the average initial count, and expressed as antilogarithm). Results after 48 h and 96 h of incubation differ from those described for bovine milk 19,20 . According to these studies, after 48 h and 96 h of refrigerated storage at 6°C, a 1 log cycle and 3 log cycles of increase in growth were observed in the total plate count, respectively.…”

Section: Resultscontrasting

confidence: 66%

Microbial flora of technological interest in raw ovine milk during 6°C storage

Sanjuan¹,

Rúa²,

García-Armesto³

2003

Int J of Dairy Tech

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Changes in the microbial flora of ovine milk of medium hygienic quality (initial mean total plate count 3.3 × 105 cfu/mL) were studied throughout refrigerated storage at 6°C. Total plate counts after 48 h of refrigerated storage (mean count 4.6 × 105 cfu/mL) were under the current standards in the European Union (EU) for raw ovine milk to be used for cheesemaking after heat treatment. However, after 96 h, mean total plate counts (1.6 × 107 cfu/mL) were above the standards. Lactococci were found at levels higher than Pseudomonas spp. in milk freshly drawn (54.5% and 3.5% of total plate count, respectively) and after 96 h at 6°C (47.9% and 33.9% of total plate count, respectively). Lactobacilli, enterococci, coliforms and thermodurics were found at values lower than lactococci and Pseudomonas spp., before and after refrigerated storage (≤ 0.08% of the total plate count). A significant growth (P < 0.001) was detected for mesophiles, Pseudomonas spp. and lactococci after 96 h of refrigeration at 6°C; however, thermodurics, coliforms, lactobacilli and enterococci, showed no significant increase (P > 0.05). Presumptive Escherichia coli (β‐glucuronidase‐positive) underwent a decrease throughout storage at 6°C.

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Section: Resultscontrasting

confidence: 66%

Microbial flora of technological interest in raw ovine milk during 6°C storage

Sanjuan¹,

Rúa²,

García-Armesto³

2003

Int J of Dairy Tech

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“…This means that only 6% of variations in lipolysis can be explained by PBC variability. According to Muir and others () and Shelley and others (), lipolytic activity was not observed when the psychrotroph count was below 5 × 10 6 to 10 7 CFU/mL (log 10 PBC between 6.7 and 7). In our study, this value was reached only during the last day storage (Figure ).…”

Section: Interrelations Between Bmscc Pbc and Lipolysismentioning

confidence: 89%

Analysis of Raw Milk Quality at Reception and During Cold Storage: Combined Effects of Somatic Cell Counts and Psychrotrophic Bacteria on Lipolysis

Gargouri

Hamed

Elfeki

2013

Journal of Food Science

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The objective of the article was to analyze the influence of psychrotrophic bacteria counts (PBCs) and somatic cell counts (SCCs) on the extent of lipolysis in bulk samples of cow's milk at reception and during cold storage. Samples of milk were analyzed on the day of sampling and subsequently during cold storage. The acidity, fat, density, chloride content, electrical conductivity (EC), bulk milk SCCs (BMSCC), and PBC values were analyzed on the day of sampling and the levels of acidity, EC, SCC, and PBC were analyzed during cold storage at 4 °C for 72 h. The SCC value 869 × 10(3) mL(-1) was higher than the recommended threshold. Lipolysis level at sampling day was related more closely with SCC than with PBC. There was no significant correlation between milk acidity and PBC among others parameters, while the milk mean density was only significant (P < 0.01) correlated with the fat content. The EC and chloride content were consistently correlated (P < 0.001) with BMSCC that allowed them to be used as indicators of mammary gland infection. The milk acidity, EC, PBC, and lipolysis levels increased in relation to the storage time at 4 °C. The lipolysis level during storage was in closer relation to the SCC, but not relation to the PBC. Effects of SCC and PBC on lipolysis decreased throughout the chilling period. It was concluded that initial lipolysis level and intrinsic milk lipoprotein lipase appear more effective than SCC and PBC on the development of lipolysis during storage.

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“…Vyletělová et al (2000b) studied the growth dynamics of psychrotrophic, mesophilic and psychrotrophic lytic microorganisms in cow's raw milk in relation to time and different temperatures. Muir et al (1978) reported that during cold storage at 6°C the total count of microorganisms increased by 1 log cycle after 48 hours and by 3 log cycles after 96 hours.…”

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confidence: 99%

Incidence of psychrotrophic lipolytic bacteria in cow's raw milk

Cempírková¹,

Mikulová²

2009

Czech J. Anim. Sci.

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AbstrAct:The contamination of bulk samples of cow's raw milk (n = 491) by psychrotrophic lipolytic bacteria (PLiBC), total count of psychrotrophic bacteria (PBC) and mesophilic bacteria (TBC) was monitored for two years on eight dairy farms and the correlations among these groups of bacteria were analysed. An increase in TBC, PBC and PLiBC and in the values of free fatty acids (FFA) was tested experimentally in three milk samples in relation to time (analyses were done in 24-hour intervals until 96 hours) and storage temperature of milk samples (4; 6.5 and 10°C). Bacterial contamination of milk was determined by culture methods in accordance with IDF standards, the values of FFA were determined by an extraction-titration method. These mean values were determined in the set of samples (n = 491): PLiBC 659 CFU/ml, PBC 2 932 CFU/ml and TBC 18 932 CFU/ml. A high correlation was proved between values of PBC and PLiBC (r = 0.87; P < 0.001) while the correlation between TBC and PBC (r = 0.65; P < 0.001) and between PLiBC and TBC (r = 0.59; P < 0.001) was on a medium level. The proportional index p i for PLiBC/PBC was 0.20, for PLiBC/TBC 0.03 and for PBC/TBC 0.16. In seasonal dynamics a statistically significant difference (P < 0.001; P < 0.05) between the increased values of TBC in the summer season was proved compared to the winter and spring season. The differences in the seasonal variation of PBC and PLiBC values were not significant. Experimental investigation of an increase in the values of tested parameters showed that at temperatures of milk sample storage 4 and 6.5°C TBC did not exceed the permissible hygienic value (100 000 CFU/ml) even after 96 hours while at 10°C it amounted to 90 000 CFU/ml after 48 hours and the limit for TBC was exceeded several times after 96 hours. PBC, which is not inhibited by cold storage to such a large extent, did not exceed the hygienic limit value for PBC (50 000 CFU/ml) even after 96 hours when milk samples were stored at 4°C, but at 6.5°C after 72 hours and at 10°C already after 48 hours the values 6 and 20 times higher, respectively, than the hygienic limit were recorded. A similar trend was observed in PLiBC, which exceeded the hazardous limit (43 000 CFU/ml) at 6.5°C after 96 hours and at 10°C already after 48 hours whereas at 4°C the limit value was not exceeded even after 96 hours. The content of FFA also increased in relation to the storage time and temperature of milk samples but in comparison with the increase in the tested groups of microorganisms the increase in FFA showed a higher correlation with storage time compared to storage temperature. A medium correlation was calculated between PLiBC and/or PBC and FFA content (r = 0.52; r = 0.57; P < 0.001).

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The Effect of Storage Temperature on Bacterial Growth and Lipolysis in Raw Milk

Cited by 32 publications

References 8 publications

Microbial flora of technological interest in raw ovine milk during 6°C storage

Microbial flora of technological interest in raw ovine milk during 6°C storage

Analysis of Raw Milk Quality at Reception and During Cold Storage: Combined Effects of Somatic Cell Counts and Psychrotrophic Bacteria on Lipolysis

Incidence of psychrotrophic lipolytic bacteria in cow's raw milk

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