Bacterial characterization of fermented sweet potato leaves by high‐throughput sequencing and their impact on the nutritional and bioactive composition

Abstract

Bacterial, nutritional, and bioactive compositions of fermented sweet potato leaves (SPL) were investigated. Three samples were utilized: control (C), natural fermentation (NF), and probiotic fermentation (PF). Bacterial composition was assessed by high-throughput sequencing. Lactobacillus plantarum and Enterococcus durans were identified in NF. Lactobacillus plantarum was also found in PF, showing a relative abundance of 90.2%. Polyphenol composition determined by HPLC changed considerably during NF decreasing its concentration to a value of 6.69 mg/g dw compared to the value found in C (42.77 mg/g dw). PF maintained the polyphenol concentration (38.64 mg/g dw) but some interconversion between polyphenols seems to occur. ABTS radical scavenging capacity value was similar in C and PF, demonstrating no changes in antioxidant activity. During PF antioxidant activity was maintained, and angiotensin-converting enzyme inhibitory activity was even improved. Fermentation was a good process for SPL. According to the parameters assessed, PF was better than NF. Novelty impact statement The effect of natural and probiotic fermentations on the bacterial composition, nutritional, and bioactive composition of sweet potato leaves was compared. Results showed that fermentation was a good process for sweet potato leaves. According to the parameters assessed, probiotic fermentation was better than natural fermentation.