Formation of vinylphenolic pyranoanthocyanins by selected indigenous yeasts displaying high hydroxycinnamate decarboxylase activity during mulberry wine fermentation and aging

The color of mulberry wine is difficult to maintain since the main chromogenic substances, anthocyanins, are severely degraded during fermentation and aging. This study selected Saccharomyces cerevisiae I34 and Wickerhamomyces anomalus D6, both displaying high hydroxycinnamate decarboxylase (HCDC) activity (78.49% and 78.71%), to enhance the formation of stable vinylphenolic pyranoanthocyanins (VPAs) pigments during mulberry wine fermentation. The HCDC activity of 84 different strains from eight regions in China was primarily screened via the deep well plate micro fermentation method, after which the tolerance and brewing characteristics were evaluated via simulated mulberry juice. The two selected strains and a commercial Saccharomyces cerevisiae were then inoculated individually or sequentially into the fresh mulberry juice, while the anthocyanin precursors and VPAs were identified and quantified via UHPLC-ESI/MS. The results showed that the HCDC-active strains facilitated the synthesis of stable pigments, cyanidin-3-O-glucoside-4-vinylcatechol (VPC3G), and cyanidin-3-O-rutinoside-4-vinylcatechol (VPC3R), highlighting its potential for enhancing color stability.