title: Effect of sublethal preculturing on the survival of probiotics and metabolite formation in set-yoghurt.
abstract: The objective of this study was to investigate the effect of preculturing of Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB12 under sublethal stress conditions on their survival and metabolite formation in set-yoghurt. Prior to co-cultivation with yoghurt starters in milk, the two probiotic strains were precultured under sublethal stress conditions (combinations of elevated NaCl and low pH) in a batch fermentor. The activity of sublethally precultured probiotics was evaluated during fermentation and refrigerated storage by monitoring bacterial population dynamics, milk acidification and changes in volatile and non-volatile metabolite profiles of set-yoghurt. The results demonstrated adaptive stress responses of the two probiotic strains resulting in their viability improvement without adverse influence on milk acidification. A complementary metabolomic approach using SPME-GC/MS and (1)H-NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Principal component analysis revealed substantial impact of the activity of sublethally precultured probiotics on metabolite formation demonstrated by distinctive volatile and non-volatile metabolite profiles of set-yoghurt. Changes in relative abundance of various aroma compounds suggest that incorporation of stress-adapted probiotics considerably influences the organoleptic quality of product. This study provides new information on the application of stress-adapted probiotics in an actual food-carrier environment.
authors.affiliation: Department of Food Technology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Sarn
authors.initials: S
authors.lastname: Settachaimongkon
authors.affiliation: Dairy Science and Technology Group, Chair of Food Quality and Design, Wageningen University, P.O. Box 17, 6700 AA, Wageningen, The Netherlands.
authors.forename: Hein J F
authors.initials: HJ
authors.lastname: van Valenberg
authors.affiliation: Dairy Science and Technology Group, Chair of Food Quality and Design, Wageningen University, P.O. Box 17, 6700 AA, Wageningen, The Netherlands.
authors.forename: Vera
authors.initials: V
authors.lastname: Winata
authors.affiliation: Dairy Science and Technology Group, Chair of Food Quality and Design, Wageningen University, P.O. Box 17, 6700 AA, Wageningen, The Netherlands.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Wang
authors.affiliation: Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen, The Netherlands.
authors.forename: M J Robert
authors.initials: MJ
authors.lastname: Nout
authors.affiliation: Dairy Science and Technology Group, Chair of Food Quality and Design, Wageningen University, P.O. Box 17, 6700 AA, Wageningen, The Netherlands.
authors.forename: Toon C M
authors.initials: TC
authors.lastname: van Hooijdonk
authors.affiliation: Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen, The Netherlands.
authors.forename: Marcel H
authors.initials: MH
authors.lastname: Zwietering
authors.affiliation: Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen, The Netherlands. Electronic address: eddy.smid@wur.nl.
authors.forename: Eddy J
authors.initials: EJ
authors.lastname: Smid
mesh_terms: D000818:Animals; D001644:Bifidobacterium / Q000254:growth & development / Q000378:metabolism*; D005285:Fermentation; D005516:Food Microbiology / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000254:growth & development / Q000378:metabolism*; D050296:Microbial Viability; D008892:Milk / Q000382:microbiology*; D019936:Probiotics / Q000032:analysis*; D015014:Yogurt / Q000382:microbiology*
keywords: Dairy; Fermented milk; Flavor; Lactic acid bacteria; Metabolomics; Stress adaptation