ISSN 2736-1756
Advanced Journal of Microbiology Research Vol. 2017
Available online at http://internationalscholarsjournals.org/journal/ajmr
© 2017 International Scholars Journals
Full Length Research Paper
Combined effects of dry matter content, incubation temperature and final pH of fermentation on biochemical and microbiological characteristics of probiotic fermented milk
Gelareh Shafiee1, Amir Mohammad Mortazavian2*, Mohammad Amin Mohammadifar1, Mohammad Reza Koushki3, Abdorreza Mohammadi4 and Reza Mohammadi2
1Department of Food Science and Technology, Faculty of Nutrition Sciences, Food Science and Technology, The International and Virtual Branch of shahid Beheshti University of Mrdial Science, P. O. Box 19395-4741, Tehran, Iran. 2Department of Food Science and Technology, Faculty of Nutrition Sciences, Food Science and Technology/National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, P. O. Box 19395-4741, Tehran, Iran.
3Department of Food Technology Reseach, National Nutrition and Food Technology Research Institute, Shahid Beheshti University (M. C.), P. O. Box 19395-4741, Tehran, Iran. 4Payame Noor University, Arak, Iran.
Accepted 19 May, 2016
Abstract
Combined effects of milk non-fat dry matter content (4, 8 or 12%), incubation temperature (37, 40 or 44°C) and final pH of fermentation (4.2 or 4.5) on biochemical and microbiological characteristics of probiotic fermented milk (Lactobacillus acidophilus LA-5, Bifidobacterium lactis BB-12, and yogurt bacteria) during and immediately after fermentation were investigated. Treatments containing higher dry matter contents had slower pH and redox potential decline rates, faster acidity increase rate, longer incubation time and greater final titrable acidity. Treatments fermented at higher temperatures with lower final pH displayed longer fermentation time and greater final titrable acidity. Treatments with higher dry matter non-fat contents, lower incubation temperatures and higher final pH of fermentation possessed greater viability of probiotic bacteria. The concentration of lactic acid in treatments increased in parallel with the titrable acidity and the concentration of acetic acid were proportional to the viability of bifidobacteria.
Key words: Bifidobacteria, fermented milk, Lactobacillus acidophilus, probiotic, viability.