the shifts of acidophilus milk at the refrigerator

abstract: acidophilus milk after preparation, with the defined characteristics of ph, titratable acidity and viable counts of lb. acidophilus, was kept at the refrigerator (5 °c) and changes of above mentioned parameters were evaluated during 21 days at 7-day intervals. the obtained results showed that the titratable acidity of product significantly (p≤0.05) increased over storage period, demonstrating the post acidification ability of lb. acidophilus at low temperatures. the ph values of acidophilus milk, due to the buffering capacity of milk, didn’t show significant (p≤0.05) decrease after 14 days, which this was contrary to the obtained result at 21 days of storage period. the viability of lb. acidophilus significantly (p≤0.05) fell down in the first two assessments due to cold shock and increase of acidity and then raised at the last assessment due to the proteolytic activity of lb. acidophilus, causing the liberation of nutritive amino acids.   keywords: acidophilus milk, lb. acidophilus, storage time.