Dynamic Changes of Lactiplantibacillus plantarum on Taste and Flavor Quality of Jujube Juice during Fermentation

To investigate the changes in the quality of jujube juice during fermentation, Lactiplantibacillus plantarum ES7-1 was used as the starter culture to ferment the jujube juice. The changes in taste and flavor were detected using an E-tongue and E-nose, combined with multivariate statistical methods, and subsequently, the key time points of fermentation were explored. Furthermore, HPLC and GC-IMS techniques were employed to determine the levels of organic acids and volatile flavor metabolites, respectively. The multivariate statistical analysis indicated that the fermentation process of jujube juice fermented with L. plantarum ES7-1 comprised four main stages: from 0 to 4 hours, from 12 to 20 hours, from 24 to 44 hours, and 48 hours. The results of E-tongue and HPLC showed that the sourness, saltiness, lactic acid content, tartaric acid content and acetic acid content of jujube juice were significantly increased (P<0.05), while the bitterness, aftertaste-B, oxalic acid content, citric acid content and malic acid content were significantly decreased (P<0.05), with the extension of fermentation time. The results of E-nose and GC-IMS showed that, the contents of alcohols, acids, esters and aromatic hydrocarbons were significantly increased (P<0.05), while the contents of aldehydes, ketones and furans were significantly decreased (P<0.05) with the extension of fermentation time. At the same time, methyl acetate, 2,3-butanedione, 3-methylbutyral, acetaldehyde and acetal were the key differential metabolites in the fermentation process of jujube juice. In conclusion, this study could provide data support for the application of L. plantarum the fermentation of jujube juice.