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Improving survival of probiotic bacteria using bacterial poly-γ-glutamic acid

Bhat, A. R., Irorere, V. U., Bartlett, T., Hill, D., Kedia, G., Charalampopoulos, D. ORCID:, Nualkaekul, S. and Radecka, I. (2015) Improving survival of probiotic bacteria using bacterial poly-γ-glutamic acid. International Journal of Food Microbiology, 196. pp. 24-31. ISSN 0168-1605

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To link to this item DOI: 10.1016/j.ijfoodmicro.2014.11.031


A major hurdle in producing a useful probiotic food product is bacterial survival during storage and ingestion. The aim of this study was to test the effect of γ-PGA immobilisation on the survival of probiotic bacteria when stored in acidic fruit juice. Fruit juices provide an alternative means of probiotic delivery, especially to lactose intolerant individuals. In addition, the survival of γ-PGA-immobilised cells in simulated gastric juice was also assessed. Bifidobacteria strains (B. longum, B. breve), immobilised on 2.5 % γ-PGA, survived significantly better (P < 0.05) in orange and pomegranate juice for 39 and 11 days respectively, compared to free cells. However, cells survived significantly better (P < 0.05) when stored in orange juice compared to pomegranate juice. Moreover, both strains, when protected with 2.5 % γ-PGA, survived in simulated gastric juice (pH 2.0) with a marginal reduction (<0.47 log CFU/ml) or no significant reduction in viable cells after four hours, whereas free cells died within two hours. In conclusion, this research indicates that γ-PGA can be used to protect Bifidobacteria cells in fruit juice, and could also help improve the survival of cells as they pass through the harsh conditions of the gastrointestinal tract (GIT). Following our previous report on the use of γ-PGA as a cryoprotectant for probiotic bacteria, this research further suggests that γ-PGA could be used to improve probiotic survival during the various stages of preparation, storage and ingestion of probiotic cells.

Item Type:Article
Divisions:Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Electron Microscopy Laboratory (CAF)
Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Food Research Group
ID Code:39037
Uncontrolled Keywords:Probiotics; γ-PGA; Bifidobacteria; Fruit juice; Simulated gastric juice


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