Ethyl esters enhancement of Jinchuan pear wine studied by coculturing Saccharomyces bayanus with Torulaspora delbrueckii and their community and interaction characteristics

To enhance the fruity flavour of pear wine by coculturing Saccharomyces yeasts with non- Saccharomyces, the coculture patterns were optimised based on the effect of different strains on the physicochemical properties and metabolites, and the interaction relationship in the coculture fermentation was also studied. These results showed that total volatiles of S. bayanus were higher than those of S. cerevisiae, especially esters, acids and phenols. The contents of total volatiles and esters were enhanced by sequential inoculation. The effect of coculturing S. bayanus Y4 with T. delbrueckii Y7 or Pichia sp. was better than that of coculturing with them with S. cerevisiae Y1, enhancing the contents of phenylethanol, acetate and ethyl esters. Furthermore, the esters (mainly ethyl esters) content was increased by 53.30%, and the acids content was decreased by 32.82% when S. bayanus Y4 was cocultured with T. delbrueckii Y7 by sequential inoculation compared with S. bayanus Y4 single inoculation. Their coculture increased the α-diversity of the fungal community and changed the correlation network between the microbiota. Redundancy analysis showed that Torulaspora was closely correlated to ethyl hexanoate, ethyl decanoate and ethyl 9-decenoate, while Saccharomyces was associated with hexanoic acid and octanoic acid. PICRUSt2 prediction revealed that Torulaspora may utilize the fatty acids produced by Saccharomyces to synthesize fatty acid ethyl esters.