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Dying in yoghurt: the number of living bacteria in probiotic yoghurt decreases under exposure to room temperature


Scharl, M; Geisel, S; Vavricka, S R; Rogler, G (2011). Dying in yoghurt: the number of living bacteria in probiotic yoghurt decreases under exposure to room temperature. Digestion, 83(1-2):13-17.

Abstract

BACKGROUND/AIMS: While probiotic bacteria are successfully used in the treatment of ulcerative colitis, the effect of commercially available probiotic products is still controversial. Here, we study whether the number of living probiotic bacteria in yoghurts is altered by an interruption of the cold chain. METHODS: Three commonly available probiotic yoghurts were kept at 4°C or put at room temperature (RT) for 6 h or 24 h. An aliquot of each yoghurt was applied on Man-Rogosa-Sharpe agar and incubated at 37°C for 48 h. Colony forming units (CFU) were counted by microscopy. RESULTS: The first yoghurt, containing Lactobacillus johnsonii, showed a significant decrease in CFU after 6 h of storage at RT, which was further pronounced after 24 h. The number of CFU of the second yoghurt, containing Lactobacillus GG, was also decreased after 6 h and further diminished after 24 h at RT. From the third yoghurt, containing Lactobacillus acidophilus, only 53.8% of the CFU remained after 6 h at RT; after 24 h, only about one fourth of the CFU were found. CONCLUSIONS: Our data demonstrate that the number of living probiotic bacteria in yoghurt products decreases dramatically after exposure to RT. This represents an important information for consumers of such products.

BACKGROUND/AIMS: While probiotic bacteria are successfully used in the treatment of ulcerative colitis, the effect of commercially available probiotic products is still controversial. Here, we study whether the number of living probiotic bacteria in yoghurts is altered by an interruption of the cold chain. METHODS: Three commonly available probiotic yoghurts were kept at 4°C or put at room temperature (RT) for 6 h or 24 h. An aliquot of each yoghurt was applied on Man-Rogosa-Sharpe agar and incubated at 37°C for 48 h. Colony forming units (CFU) were counted by microscopy. RESULTS: The first yoghurt, containing Lactobacillus johnsonii, showed a significant decrease in CFU after 6 h of storage at RT, which was further pronounced after 24 h. The number of CFU of the second yoghurt, containing Lactobacillus GG, was also decreased after 6 h and further diminished after 24 h at RT. From the third yoghurt, containing Lactobacillus acidophilus, only 53.8% of the CFU remained after 6 h at RT; after 24 h, only about one fourth of the CFU were found. CONCLUSIONS: Our data demonstrate that the number of living probiotic bacteria in yoghurt products decreases dramatically after exposure to RT. This represents an important information for consumers of such products.

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5 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Gastroenterology and Hepatology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2011
Deposited On:04 Mar 2011 14:45
Last Modified:11 Jul 2016 07:26
Publisher:Karger
ISSN:0012-2823
Additional Information:© 2011 S. Karger AG
Publisher DOI:10.1159/000308715
Related URLs:http://www.karger.com/Article/FullText/308715
PubMed ID:20838050
Permanent URL: http://doi.org/10.5167/uzh-47336

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