Screening, Characterization and Mutagenesis Breeding of Monascus Isolates with High Esterification Activity

Esters are predominant fragrance components in various traditional fermented foods. Hongqu rice wine, a beverage gaining popularity among young consumers in China, largely owes its aromatic profile to esterases derived from Monascus species. However, research on esterification characteristics of Monascus strains remains limited, constraining efforts to improve the quality and flavor of Hongqu rice wine. To better understand their esterification characteristics of commercial Monascus strains from different regions of China and further develop a high-quality esterifying Monascus strain for the liquor industry, we identified five Monascus isolates from red koji samples used in rice wine fermentation. Their esterification activity was evaluated by preparing red koji through solid-state fermentation of wheat bran under conditions simulating industrial production. Among the isolates, M. purpureus M21 exhibited the highest reported esterification activity to date, reaching 88.5 ± 8.6 U. Through atmospheric and room-temperature plasma (ARTP) mutagenesis breeding, the esterification activity of M. purpureus M21 was further enhanced by 41% to 124.8 U. In summary, this study not only figures out the properties of commercial esterifying Monascus from diverse regional sources but also significantly enhances the esterification performance of a potent esterifying Monascus strain without invoking GMO controversies. This high-performance esterifying Monascus strain presents a promising fermentation starter to enhance the flavor profile of Hongqu rice wine and diverse fermented beverages, thereby meeting evolving consumer preferences.