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Page No. : 31-35

ABSTRACT

The objective of milk pasteurization is to make it safe and extend its shelflife to few weeks. Pasteurized milk is, however, perishable and evaluation of its quality is one of the prime concerns. The objectives of pasteurization are usually not met in most parts of India and the pasteurized milk is sold with shelf life warrantee of only two to three days. In the study area, evaluation of the bacteriological quality of pasteurized milk is not a routine feature and spoilage of pasteurized milk has been observed especially during summer season. This has necessitated this investigation. Eighty milk samples, 20 each of four market brands of pasteurized milk, were collected during the period May to September, 2010. Each sample was evaluated for Standard Plate Count (SPC), Coliform Count, Laboratory Pasteurization Count (LPC) and Psychrophilic Count. Fifty three (66.25%), 59 (73.75%) and 61 (76.25%) of 80 samples were having SPC, coliforms and LPC well above and 27(33.75%), 21 (26.25%) and 19 (23.75%), respectively, within the acceptable limits prescribed as per ISI standards/guidelines. Psychrophilic bacteria, varying from 1x103 - 4.9x106/ml, were invariably present in each sample. Based on the quality control tests on eighty samples of pasteurized milk, levels of different bacterial counts were above the permissible limits across the four brands indicating one or more factors like imperfect pasteurization, inadequately sanitized pasteurizing equipment, and use of improperly sanitized utensils, post pasteurization contamination and poor hygienic conditions in raw milk production.

Keywords: Coliform count, laboratory pasteurization count, microbial quality, pasteurized milk, psychrophilic count, standard plate count.