Effect of time of inoculation, starter addition, oxygen level and salting on the viability of probiotic cultures during Cheddar cheese production

The effect of oxygen level, time of inoculation of probiotics, starter addition and salting on viable counts of five probiotic bacteria in curds and whey was examined in simulated Cheddar manufacture. Probiotic bacteria grew little during fermentation, and one strain (Bifidobacterium longum 15708) was oxygen-sensitive. Between 29 and 92% of probiotic bacteria were found in curds, and cell distribution between curds and whey was influenced by strain, time of inoculation and salting. Inoculation of probiotics in milk before renneting resulted in almost half the cell losses in whey compared with addition just before cheddaring. Inoculation of probiotics in milk improved their subsequent stability by about 1 log over a 20-day storage period. Salting resulted in approximately 13% loss of cells in whey during processing and in a 3 log cfu g−1 greater viability loss of B. longum after 3 days of storage.