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Combined effects of incubation temperature, type of starter bacteria and final pH of fermentation on microbiological, biochemical and sensory characteristics of probiotic Doogh (Iranian drink based on fermented milk)
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Zohre Delshadian   , Reza Mohammadi , Saeedeh Cheledavan , Mehdi Shadnoush , Elahe Ahmadi , Amir Mohammad Mortazavian |
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Abstract: (6132 Views) |
| Introduction: Viability of
probiotic microorganisms in the final product is the most important qualitative
parameter which is affected by many factors, including type of starter calture,
pH, acidity, redox potential, incubation temperature and refrigerating
temperature and time. In this study, the combined effects of three important
factors including type of starter calture, incubation temperature and final pH
of fermentation on viability of two probiotic species Lactobacillus
acidophilus and Bifidobacterium lactis and also the biochemical and
sensory characteristics of their product, doogh, were investigated. Materials and
methods: Different
treatments of probiotic Doogh were prepared with yoghurt starter culture and
two probiotic strains Lactobacillus acidophilus La-5 (A) and Bifidobacterium lactis Bb-12 (B) using reconstituted skim milk powder with
6% of nonfat solid milk by incubating at 38°C or 44°C until pH 4.0 or 4.5 and
keeping in 4°C or 8°C storage temperature for 21 days. The count of probiotic
bacteria and biochemical characteristics were performed during fermentation and
over the refrigerating period. The sensory attributes of treatments were
determined at the end of fermentation and refrigeration. Results: In general, the greatest drop in mean pH rate,
increase in mean acidity rate, increase in mean redox potential rate and
shortest incubation time were observed in treatments with incubation in 44°C
and final pH of 4.5. Among the selected treatments regarding the taste
acceptance, ABY3-38-4.5 treatment revealed the greatest viability of the two
probiotic bacteria in both storage temperature of 4°C and 8°C. After 21 days of
refrigeration, ABY1-38°C-4.0 and ABY2-38°C-4.0 achieved the highest and lowest
total acceptance scores, respectively. Conclusion: All of the variables in this research significantly
affected the qualitative properties of probiotic yogurt. Either the
fermentation temperature of 38°C (in spite of need for prolonged fermentation)
or the final pH of 4.5 resulted in increased viability of the probiotics,
although the final pH of 4 resulted in better sensory evaluation. |
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| Keywords: Lactobacillus Acidophilus, Bifidobacterium Lactis, Probiotic |
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Full-Text [PDF 1489 kb]
(1363 Downloads)
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Type of Study: Research |
Subject:
General
Received: 2014/07/11 | Accepted: 2014/12/22 | Published: 2015/06/10
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