Preliminary investigation of the combined effect of heat treatment and incubation temperature on the viability of the probiotic micro-organisms in freshly made yogurt

Authors

  • A M MORTAZAVIAN,

    Corresponding author
    1. Department of Food Science and Technology, Ayatollah Amoli Unit, Azad Islamic University, PO Box 678, Amol, Iran,
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  • M R EHSANI,

    1. Department of Food Technology, Biotechnology and Engineering, Faculty of Agriculture, University of Tehran, PO Box 31585-4111, Karaj, Iran,
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  • S M MOUSAVI,

    1. Department of Food Technology, Biotechnology and Engineering, Faculty of Agriculture, University of Tehran, PO Box 31585-4111, Karaj, Iran,
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  • J A REINHEIMER,

    1. Programa de Lactologia Industrial, Faculted de Ingenieria Quimica (Universidad Nacional del Litoral), Santiago del Estero 2829, 3000 Santa Fe, Argentina
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  • Z EMAMDJOMEH,

    1. Department of Food Technology, Biotechnology and Engineering, Faculty of Agriculture, University of Tehran, PO Box 31585-4111, Karaj, Iran,
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  • S SOHRABVANDI,

    1. Department of Food Science and Technology, Ayatollah Amoli Unit, Azad Islamic University, PO Box 678, Amol, Iran,
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  • K REZAEI

    1. Department of Food Technology, Biotechnology and Engineering, Faculty of Agriculture, University of Tehran, PO Box 31585-4111, Karaj, Iran,
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*Author for Correspondence. E-mail: mortazvn@ut.ac.ir

Abstract

The combined effects of heat treatment and incubation temperature were studied on the viability and fermentation time of probiotics in ABY 1 probiotic yogurt (Lactobacillus acidophilus, Bifidobacterium spp. and yogurt bacteria). Three levels of heat treatment (85°C for 30 min, 95°C for 5 min and 95°C for 15 min) and three levels of incubation temperature (37, 40 and 44°C) were selected. At the end of fermentation, the maximum viability of probiotics (for both L. acidophilus and Bifidobacterium spp.) was observed when the milk was heated at 95°C for 15 min and incubated at 37°C. Incubation time was only affected by the incubation temperature and, at 37°C, the longest incubation time of about 6 h was needed to achieve the highest viable counts of L. acidophilus and Bifidobacterium spp.

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