Development of probiotic Cheddar cheese containing Lactobacillus acidophilus, Lb. casei, Lb. paracasei and Bifidobacterium spp. and the influence of these bacteria on proteolytic patterns and production of organic acid

Three batches of Cheddar cheeses (Batch 1, with only starter lactococci; Batch 2, with lactococci and Lactobacillus acidophilus 4962, Lb. casei 279, Bifidobacterium longum 1941; Batch 3, with lactococci and Lb. acidophilus LAFTI® L10, Lb. paracasei LAFTI® L26, B. lactis LAFTI®B94) were manufactured in triplicate to study the survival and influence of probiotic bacteria on proteolytic patterns and production of organic acid during ripening period of 6 months at 4 °C. All probiotic adjuncts survived manufacturing process and maintained their viability of >7.5 log10 cfu g−1 at the end of ripening. The number of lactococci decreased by one to two log cycles, but their counts were not significantly different (P>0.05) in control and probiotic cheeses. No significant differences were observed in composition (fat, protein, moisture, salt content), but acetic acid concentration was higher in probiotic cheeses. Assessment of proteolysis during ripening showed no significant differences (P>0.05) in the level of water-soluble nitrogen (primary proteolysis), but the levels of secondary proteolysis indicated by the concentration of free amino acids were significantly higher (P<0.05) in probiotic cheeses. SDS-PAGE results on hydrolysis of αs-CN after 6 months were consistently higher in probiotic cheeses (19.28%, 46.99% and 63.42% in Batch 1, Batch 2 and Batch 3, respectively). Proteolytic activity, however, remained relatively low for all cheeses due to the low temperature of ripening (4 °C). Results demonstrated that Cheddar cheeses can be an effective vehicle for delivery of probiotic organisms.