Proliferation of and toxin formation byStaphylococcus aureus in skimmed and acidified milk as related to different heat treatments and incubation temperatures
✍ Scribed by Al-Talibi, Abdul Amir A.
- Publisher
- John Wiley and Sons
- Year
- 1977
- Tongue
- English
- Weight
- 535 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0027-769X
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✦ Synopsis
Abstract
This study was carried out in an attempt to minimize the total population of St. aureus in skimmed and acidified milk and henceforth to avoid the endotoxin formation in milk and milk products prior to manufacturing. Different heat treatments and incubation temperatures were used for normal and acidified milk. The following results were obtained:
The activated cells received a lethal effect. The surviving cells greatly depended upon incubation temperatures. The recovery was most suitable at low temperatures and it was relatively disturbed at higher incubation temperatures.
The lag phase continued for a long time prior to cell division.
The proliferation gave sigmoidal curves at all heat treatments.
A gradual decline was found in N‐values. However, compared with those of the control, a high number of cell divisions took place at low incubation temperatures (25 and 30 °C). The rate of proliferation was low in all treatment cases.
The coagulase positive reactions showed great variations in time intervals. Low degree of firmness of blood plasma coagulation was obtained at incubation temperatures of 25, 30 and 45 °C, whereas the highest degree was obtained at 37 °C.
All above results were almost identical when experiments were performed on both acidified and normal milk with a pH 6.8.