Enhancing cider quality through co‐fermentation with acid protease and esterase‐producing Metschnikowia species and Saccharomyces cerevisiae

Abstract BACKGROUND To date, cider production has primarily relied on Saccharomyces cerevisiae . Introducing novel non‐ Saccharomyces yeasts can enhance the diversity of cider properties. Among these, the Metschnikowia genus stands out for its ability to produce hydrolytic enzymes that may impact the sensorial and technological properties of cider. This study focused on evaluating the impact of three Metschnikowia species – Metschnikowia koreensis (Mk), M. reukaufii (Mr), and M. pulcherrima (Mp) – which exhibit acid protease and esterase activity, on the quality enhancement of cider. RESULTS The research findings indicate that the overall quality of cider produced through co‐fermentation with these species surpassed that of cider fermented with mono‐fermentation of S. cerevisiae (Sc). The cider fermented with the Sc + Mk combination exhibited the lowest levels of harsh‐tasting malic acid and higher levels of softer lactic acid. Sensory array analysis also demonstrated that the Sc + Mk fermented cider exhibited high sensor response values for compounds contributing to a complex overall olfactory composition and richness. Furthermore, the Sc + Mk fermented cider exhibited the highest total quantity and variety of volatile organic compounds (VOCs). Specifically, the concentrations of phenethyl alcohol, 3‐methyl‐1‐butanol, ethyl octanoate, and decanoic acid were notably elevated in comparison with other groups. CONCLUSION This study illustrates that Metschnikowia species, particularly M. koreensis , show significant potential as starters for cider due to their various technological properties, including acidity modulation, aroma enhancement, and color improvement. The findings of this study provide a foundation for improving cider quality by co‐fermenting S. cerevisiae with innovative starter cultures. © 2024 Society of Chemical Industry.