Analysis of Differences in Flavor between Sour Tea Produced by Inoculated and Natural Fermentations

This study explored the effect of inoculated fermentation with Leuconostoc mesenteroides and Zygosaccharomyces bisporus on the flavor of sour tea. The flavor of sour tea was analyzed using an electronic nose, an electronic tongue, gas chromatography-ion mobility spectrometry (GC-IMS), liquid chromatography-tandem mass spectrometry (LC-MS/MS), and sensory evaluation. Inoculated sour tea was richer in alcohols, aromatics, and organic sulfides than naturally fermented sour tea. A total of 64 volatile flavor compounds were detected, and 17 characteristic aroma components were identified. Among them, the relative contents of nine aroma components were significantly higher in inoculated tea than in naturally fermented tea, with the former exhibiting prominent fruity, winey, and woody aromas. Inoculated fermentation resulted in higher umami richness but astringency and sourness of sour tea compared with natural fermentation. A total of 164 differential metabolites were detected, which contributed to the taste formation of sour tea. Compared with naturally fermented sour tea, the relative contents of 72 metabolites were significantly increased, while the relative content of 92 metabolites were significantly decreased in inoculated sour tea. The sensory evaluation results indicated that the flavor of inoculated sour tea was superior and its acceptability was higher. This study showed that inoculated fermentation significantly improved the flavor quality of sour tea, providing a new approach for the development and production of sour tea.