Quality and metagenomic evaluation of a novel functional beverage produced from soy whey using water kefir grains

Abstract

Soy whey is a by-product from tofu production industry, there is an urgent need to develop a better approach for its utilization to avoid environmental pollution. In this study, the quality and metagenomics of the water kefir-fermented soy whey beverage (WKFS) were evaluated. The changes in physicochemical characteristics and microbial composition during fermentation were studied. The pH, total soluble solids and anti-nutritional component got a dramatic decline. After 2-days of fermentation, the DPPH scavenging ability, ABTS radical scavenging ability and ferric reducing antioxidant power of WKFS were significantly increased from 40.55%, 38.65% and 46.50 μg/L to 72.34%, 87.06% and 56.22 μg/L, respectively. The total flavonoid, total phenolic and the isoflavones aglycones were also significantly increased after 2-days of fermentation. The result also showed that many new aromatic volatile compounds were produced which increased the sensory quality of soy whey after fermentation. In addition, the results of the microbial growth dynamics, molecular identification and, gene functional analysis provided strong evidence to these changes in chemical and microbiological parameters during fermentation. Therefore, the findings of this research provide strong evidence that a new type of functional beverage can be produced from soybean whey using water kefir as a suitable starter.