Metabolism of Blueberry Anthocyanins During Probiotic Fermentation

Streptococcus thermophilus,Bifidobacterium bifidum and Lactobacillus plantarum were used to ferment the culture medium containing blueberry anthocyanin extracts. The changes of bacterial number,antioxidant capacity of fermented medium in vitro,and profiles of organic acids,anthocyanins and phenolic acids were investigated. The results showed that after 48 h of fermentation,the number of viable strains of the three probiotics increased to about 8.0 lg CFU/mL,and the number of viable strains of Bifidobacterium bifidum was the highest(P<0.05). Probiotic fermentation significantly(P<0.05)enhanced the scavenging capacity of ABTS⁺· radicals of culture medium in vitro,the medium fermented by Bifidobacterium bifidum had the strongest antioxidant capacity among all the mediums. Moreover,Lactobacillus plantarum synthetized more lactic acid than the other two microbial strains in the culture medium containing blueberry anthocyanins. Anthocyanin contents in the medium decreased gradually during probiotic fermentation. The anthocyanin profile of medium fermented by Bifidobacterium bifidum was significantly(P<0.05)different from that fermented by Lactobacillus plantarum and Streptococcus thermophilus according to principal component analysis. Besides,probiotic fermentation led to the declines of contents of chlorogenic acid,p-coumaric acid and caffeic acid. Instead,contents of gallic acid,syringic acid and ferulaic acid in the culture medium exhibited an increasing trend. The phenolic acid profile was also markedly affected by the applied microbial strains. The aforementioned results can provide guidance for further investigation of metabolisms of anthocyanins during probiotic fermentation of fruit juices.