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

Document Type: Research article

Authors

1 Skin Research Center, Vice Presidency of Research and Technology, Shahid Beheshti University of Medical Sciences, P.O. Box 19395-4741, Tehran, Iran.

2 Department of Food TechnologyResearch, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, P.O. Box 19395-4741, Tehran, Iran.

3 Department of Food Science and Technology, Faculty of Nutrition, Tabriz University of Medical Sciences, Tabriz, Iran.

4 Department of Food Science and Technology, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences, Food Science and Technology, Shahid Beheshti University of Medical Sciences, P.O. Box 19395-4741, Tehran, Iran.

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.

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