title: Whey protein isolate improves acid and bile tolerances of Streptococcus thermophilus ST-M5 and Lactobacillus delbrueckii ssp. bulgaricus LB-12.
abstract: Acid tolerance and bile tolerance are important probiotic characteristics. Whey proteins contain branched-chain amino acids, which play a role in muscle building and are popular among athletes. Increasing emphasis is being placed on diets containing less carbohydrate, less fat, and more protein. The effect of incremental additions of whey protein isolate (WPI) on probiotic characteristics of pure cultures is not known. The objective of this study was to determine the influence of added WPI on acid tolerance and bile tolerance of pure cultures of Streptococcus thermophilus ST-M5 and Lactobacillus bulgaricus LB-12. The WPI was used at 0 (control), 1, 2 and 3% (wt/vol). Assessment of acid tolerance was conducted on pure cultures at 30-min intervals for 2h of acid exposure and bile tolerance at 1-h intervals for 5h of bile exposure. Use of 1, 2, and 3% WPI improved acid tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12. The highest counts for acid tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12 were obtained when 3% WPI was used. Use of 2 and 3% WPI improved bile tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12 over 5h of bile exposure. The use of WPI is recommended to improve acid and bile tolerance of the yogurt culture bacteria Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12.
authors.affiliation: School of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge 70803.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Vargas
authors.affiliation: School of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge 70803.
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Olson
authors.affiliation: School of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge 70803. Electronic address: karyana@agcenter.lsu.edu.
authors.forename: Kayanush J
authors.initials: KJ
authors.lastname: Aryana
mesh_terms: D001646:Bile / Q000378:metabolism*; D005516:Food Microbiology; D048668:Lactobacillus delbrueckii / Q000187:drug effects* / Q000378:metabolism; D019936:Probiotics; D048249:Streptococcus thermophilus / Q000187:drug effects* / Q000378:metabolism; D000067816:Whey Proteins / Q000494:pharmacology*; D015014:Yogurt / Q000382:microbiology
chemical_list: D000067816:Whey Proteins
keywords: culture; probiotic; whey protein isolate; yogurt