title: Improving survival of probiotic bacteria using bacterial poly-γ-glutamic acid.
abstract: 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 (Bifidobacteria longum, Bifidobacteria 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 (pH2.0) with a marginal reduction (<0.47 log CFU/ml) or no significant reduction in viable cells after 4h, whereas free cells died within 2h. 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.
authors.affiliation: Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, WV1 1LY, United Kingdom.
authors.forename: A R
authors.initials: AR
authors.lastname: Bhat
authors.affiliation: Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, WV1 1LY, United Kingdom.
authors.forename: V U
authors.initials: VU
authors.lastname: Irorere
authors.affiliation: Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, WV1 1LY, United Kingdom.
authors.forename: T
authors.initials: T
authors.lastname: Bartlett
authors.affiliation: Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, WV1 1LY, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Hill
authors.affiliation: Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, WV1 1LY, United Kingdom.
authors.forename: G
authors.initials: G
authors.lastname: Kedia
authors.affiliation: Department of Food and Nutritional Sciences, University of Reading, PO Box 226, White knights, Reading RG6 6AP, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Charalampopoulos
authors.affiliation: Department of Food and Nutritional Sciences, University of Reading, PO Box 226, White knights, Reading RG6 6AP, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Nualkaekul
authors.affiliation: Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, WV1 1LY, United Kingdom. Electronic address: I.Radecka@wlv.ac.uk.
authors.forename: I
authors.initials: I
authors.lastname: Radecka
mesh_terms: D001628:Beverages / Q000382:microbiology*; D001644:Bifidobacterium / Q000187:drug effects* / Q000502:physiology; D032084:Citrus sinensis / Q000382:microbiology; D061353:Food Storage; D018698:Glutamic Acid / Q000494:pharmacology*; D029561:Lythraceae / Q000382:microbiology; D050296:Microbial Viability / Q000187:drug effects*; D019936:Probiotics
chemical_list: D018698:Glutamic Acid
keywords: Bifidobacteria; Fruit juice; Probiotics; Simulated gastric juice; γ-PGA