Physicochemical and hygienic effects of Lactobacillus acidophilus in Iranian white cheese.

Increasing incidence of food-borne disease along with its social and economic consequences have led to conducting extensive research in order to produce safer food and develop new antimicrobial agents; among them, extensive use of probiotics and bacteriocins as biological additives is of significant importance. The aim of the present study was to evaluate the interactions (growth behavior and survival) of Listeria monocytogenes and Lactobacillus acidophilus in various stages of production, ripening and storage of Iranian white cheese. Changes in pH values at different stages of cheese ripening, along with changes in organoleptic properties of cheese were also assessed. Compared to other treatments, in the treatment of cheese with probiotic agent without starter, the most significant decrease in Listeria monocytogenes count at the end of ripening stage was observed (3.16 Log per gram cheese compared with the control group) (p < 0.05). Survival of probiotic bacteria in control samples of cheese were significantly higher when compared to cheese sample contaminated with Listeria (p < 0.05). White probiotic cheese with starter had the highest of sensory acceptability (p < 0.05). Listeria Monocytogenes count decreased during ripening period of probiotic white cheese but the bacteria survived in probiotic white cheese. Lactobacillus acidophilus count decreased during ripening period of white cheese but it did not lower to less than 10(6) CFU per g at the end of ripening and storage periods.