Changes of microflora in raw milk during storage at 7 deg C
1998
Popovic, S. (Veterinarski specijalisticki institut, Zajecar (Yugoslavia)) | Katic, V. | Stojanovic, L.
Changes of microflora in 60 samples of raw milk during storage at 7 deg C were investigated. In the first three days the number of mesophilic, psychrophilic and termoresistant microorganisms increased slightly above one logarithmic value. After 3rd to 6th day the number of mesophilic organisms increased for 1.2 log value, 1.6 log value of the psychrophilic organisms and for 2.2 log value of the number of termoresistant organisms. Between 6th and 9th day the number of psychrophilic organisms indicated the highest increasing (3.1 log value), then the number of mesophilic organisms for 1.49 log value, but the counts of termoresistant organisms decreased for 1.3 log value. From mesophilic organisms, those from genus Micrococcus was in the highest percentage. In mesophilic microflora the Pseudomonas aeruginosa was appeared only of the 6th day. From psychrophilic organisms, those from genus Micrococcus were present in the highest percentage, at beginning of the study, i.e. in raw milk. During storage of milk at 7 deg C the microflora changed with decreasing of micrococci and an increase of the Pseudomonas aeruginosa and Alcaligenes spp. During the period of investigation of termoduric bacteria Micrococcus luteus and Enterococcus faecalis were present. At beginning of the study Bacillus subtilis was present in a high percentage (26%) but decreased during the storage to only 6%. On the basis of the changes of microflora in milk stored at 7 deg C it could be concluded that it could be held at least for 72 hours.
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