Development of prebiotic steamed buns and their influence on gut microbiota and the glycemic index in simulated digestion

This study investigated the effects of adding purple potato anthocyanin (PPA) and Longjing tea powder (LTP) as prebiotics to steamed buns on gut microbiota (GM) and blood glucose levels. The effects of simulated digestion experiments on GM and blood glucose, as well as the results of high-throughput 16S rRNA sequencing, were analyzed. The combined results showed that both kinds of prebiotics significantly promoted the proliferation of Lactobacillus paracasei K56, Lactobacillus plantarum LP-ONLLY, and Lactococcus lactis LC-Plasma. The addition of 50 mg/mL LTP water extract and 2.5 mg/mL PPA water extract had considerable inhibitory effects on Escherichia coli ATCC25922, yielding inhibition zone diameters of 9.16 ± 0.02 and 11.17 ± 0.03 mm, respectively. Both PPA and LTP buns increased the abundance of probiotics in human GM. Prebiotic–xylitol steamed buns could regulate the structure of GM by decreasing the abundance of harmful bacteria (including Shigella and Enterobacter ) and increasing the abundance of beneficial bacteria (including Bifidobacterium , Lactobacillus , and Veillonella ). Prebiotic steamed buns could significantly reduce the rate of reducing sugar release, the estimated glycemic index (eGI), and the estimated glycemic load (eGL), providing products with a medium glycemic index and potential natural prebiotics as resources for the development of functional staple foods. • PPA and LTP were used as prebiotics in making steamed buns. • LTP and PPA combined had the best effect on regulating the gut microbiota. • PPA, LTP, and PPA + LTP prebiotic steamed buns were classified as medium-GI foods.