Use of kombucha consortium to transform soy whey into a novel functional beverage

[Display omitted] •Transforming soy whey into a novel functional beverage using kombucha consortium.•The antioxidant capacity of kombucha-fermented soy whey was significantly enhanced.•Kombucha-fermented soy whey showed antibacterial activity.•The fermentation produced new aroma-active volatiles, which imparted fruity flavor. Soy whey is a liquid by-product from tofu and soy protein manufacturing, and is usually discarded, leading to environmental pollution. This study investigated the feasibility of transforming soy whey into a novel functional beverage using kombucha consortium. Changes in chemical compositions and bioactivities were monitored during the fermentation. The fermentation induced a reduction in pH and increase in total titratable acid content after fermentation. The antioxidant capacity of kombucha-fermented soy whey (KFSW) was significantly enhanced, as assessed by DPPH scavenging ability, ABTS radical scavenging ability, ferric reducing antioxidant power and reducing power. Furthermore, KFSW showed antibacterial activity against Staphylococcus aureus, Bacillus subtilis and Escherichia coli. In addition, the fermentation produced new aroma-active volatiles, especially esters and higher aldehydes, which imparted fruity flavor to soy whey and improved its sensory quality. Therefore, kombucha-fermentation can transform soy whey into a novel functional beverage, which could add value to the soy process by-product.