Growth, viability, and proteolytic activity of bifidobacteria in whole camel milk

Four species of bifidobacteria were evaluated for growth, viability, and proteolytic activity in whole camel milk, and comparison was made with whole cow milk. Growth of all species in either whole milk was characterized by the appearance of two logarithmic phases following anaerobic incubation at 37 degrees C for 36 h. The growth rate of Bifidobacterium longum 15707 was higher in camel milk than in bovine milk and was higher for Bifidobacterium angulatum 27535 in bovine milk than in camel milk. Bifidobacterium bifidum 2715 and Bifidobacterium breve 2258 showed the same trend as B. angulatum 27535 after 16 h of postinoculation. Viable counts of all species except B. bifidum 2715 increased in the fermented whole milks during the first 3 d of storage at 4 degrees C. However, such counts did not change in unfermented milk, except for B. longum 15707, which showed an increase in viable counts after 12 d of storage. Viability of all species in both fermented and unfermented milks was unaffected during refrigerated storage for 15 d. All species except B. longum 15707 showed higher proteolytic activity in fermented camel milk than in bovine milk. However, proteolytic activity of all species except B. breve 2258 started at d 9 in unfermented camel milk only and increased sharply until the end of the storage period.