Abstract
This study was performed to detect the spore forming bacteria that frequently represent the major bacteria in sterilized milk that might cause milk deterioration. A total of 46 isolates were noticed in sterilized milk produced by the Mosul milk plant through a period of four months (July, August, September and October). These isolated bacteria all belonged to the genus Bacillus which included B.subtilis, B.circulans, B.licheniformis and B.megaterium that represented 52,23,15 and 8% , respectively. The influence of storing process for 4 weeks at 35°C on the number of spores and upon the ratio of deteriorated sterilized milk samples revealed that the number of spores increased upon the increase in storage time and ranged from 3-97 spores/ml. and it was also noticed that the percentage of deteriorated milk samples were relatively high, 5% during the third week of storage in August followed by another 5% the next week. While during September, the deterioration took place through the fourth week and had 10% of the stored bottles, whereas no deterioration was observed through both July and October. The acidity levels of sterilized milk were within the normal, 0.18 – 0.23 % which leads to a conclusion that deterioration due to the proteolysis of milk proteins.
