Combined Effects of Inoculation Level and Sequence on Biochemical and Microbiological Characteristics of Probiotic Doogh

Abstract

The combined effects of inoculation level (4 or 8-fold compared to standard inoculation) and sequence (standard inoculation before fermentation and 3-fold inoculation at the end of fermentation=1+3, Two-fold inoculation before fermentation and the same at the end of fermentation=2+2, 2+6, 4-fold before fermentation=4, 4+4, and 8) of culture inoculum containing probiotics on biochemical and microbiological characteristics of probiotic Doogh during fermentation and over 21 days of refrigerated storage (4˚C) were investigated. The probiotic microorganisms were L. acidophilus LA-5 and Bifidobacterium lactis BB-12. Overall, the treatments 8, 4 and 4+4 resulted in the highest viability at the end of fermentation as well as at early days of refrigerated storage. During the second half of cold storage period, the greatest viability of probiotics was related to the treatment 2+6. The treatment ‘8' showed the shortest incubation time as well as the highest pH drop rate and acidity increase rate during fermentation and over the storage period.