Prebiotic activity of Indonesian black soybean (Glycine max (L.) Merr) anthocyanin

Anthocyanins are well known have potential as a prebiotic source as they could increase the growth of probiotic bacteria and inhibit the growth of pathogenic bacteria. This study was conducted to obtain the prebiotic activity from Indonesian black soybean anthocyanin. Black soybean anthocyanin was extracted with 80% methanol + 1 M HCl solution under room temperature using a water bath shaker. In vitro prebiotic activity assay of anthocyanin extract was done using the spread plate technique to measure the growth of probiotic and pathogenic bacteria.  Lactobacillus acidophilus was used as the probiotic bacteria, while Escherichia coli and Salmonella typhi were used as the pathogenic bacteria. The whole soybean flour and extract residue were used to compare with the prebiotic activity of the extract. The total monomeric anthocyanin content of the extract was 0.33 mg/g. The highest prebiotic activity was obtained from anthocyanin extract, followed by the whole black soybean flour and anthocyanin extract residue, respectively. The prebiotic activity of the extract was higher compare with prebiotic activity standard (>0.25). It could be concluded that Indonesian black soybean anthocyanin can be used as the source of prebiotic food.