African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 4946

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.
Email: [email protected]/[email protected]

  • Article Number - B91E00213613
  • Vol.4(12), pp. 1265-1274, June 2010
  •  Accepted: 19 May 2010
  •  Published: 18 June 2010

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.

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