The effects of Zygosaccharomyces rouxii fermentation on polyphenol profile, antioxidant properties, α-glucosidase inhibitory activity, and flavor compounds of Cynanchum auriculatum Royle ex Wight beverages

Abstract

This study investigated the effect of Zygosaccharomyces rouxii (Z. rouxii) fermentation on the functional properties and flavor quality of Cynanchum auriculatum Royle ex Wight beverages (CAB). The findings revealed that Z. rouxii fermentation significantly altered the acid and sugar profiles, increased the ethanol content (P < 0.05), raised the total phenolic content by 11.50 %, and elevated the total flavonoid content by 60.30 %. The fermentation process also modified the polyphenol profiles, significantly affecting the levels of gallic acid, kaempferol, and gossypol (P < 0.05). Additionally, the antioxidant and α-glucosidase inhibitory activities were significantly enhanced (P < 0.05), particularly in ABTS (98.95 % inhibition) and DPPH (90.62 % inhibition) free radical scavenging abilities, as well as α-glucosidase inhibition (98.95 %). Analysis of volatile metabolites (VMs) identified 98 differential metabolites between fermented and non-fermented CAB, and 20 key flavor metabolites with a relative odor activity value (rOAV) of ≥1 were identified. Z. rouxii fermentation primarily changed the types and concentrations of alcohols, esters, and terpenoids in CAB, thereby enhancing its "floral, sweet, and woody" flavor profile. These findings provide valuable insights for biochemical research on fermented CAB.