Changes in population of S. [Salmonella] enterica serotype Enteritidis in experimentally contaminated milk depending on temperature and acidity | Promena populacije S. [Salmonella] enterica serotip Enteritidis u eksperimentalno kontaminiranom mleku u zavisnosti od temperature i kiselosti
2009
Rajić-Savić, N., PKB Korporacija, Padinska Skela (Serbia). Dijagnostička laboratorija
The objective of the work was to examine the survival of Salmonella in milk depending on the changes of the total number of bacteria, pH and temperature. In the study, 0.1 ml of 24-hour bouillon culture of Salmonella enteritidis was inoculated in raw collective milk (10**4 cfu/ml) and in marketed pasteurized milk (10**2 cfu/ml) each. The examined milk samples were maintained at room temperature and at a temperature of 7 deg C. At the beginning of the examinations, after 24h, 48h, 72h, after 7, 14, and 21 days, decimal solutions were made from the milk, and, following incubation, the number of Salmonella enteritidis was determined (Rambach agar), the total number of bacteria (base for total number of bacteria) by multiplying the number of grown colonies and the corresponding solution, and the milk pH was measured. There was a bigger reduction of Salmonella enteritidis at room temperature because the pH value dropped more swiftly. The lowest pH at which Salmonella enteritidis was isolated from experimentally contaminated milk was 3.88. The results of the examinations show that Salmonella can adapt to biochemical processes during milk acid fermentation of soft cheeses. No Salmonella bacteria were isolated from experimentally contaminated pasteurized milk at both maintenance temperatures after seven day of investigations.
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