Abstract: The purpose of this work was to explore the effect of fermentation with lactic acid bacteria, yeast or acetic acid bacteria on the flavor of black tea infusion. The volatile components of fermented tea infusion were analyzed by sensory evaluation and headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). It was shown that fermentation remarkably increased the fruity aroma and decreased the flowery, sweet and grassy aroma of black tea infusion. Besides, the roasted aroma was reduced after fermentation with yeast or lactic acid bacteria, but was increased after acetic acid bacterial fermentation. A total of 46 volatile components were identified in the tea infusion fermented by yeast, in which the contents of alcohols, esters and acids increase to 1 605.93, 7 715.82 and 596.15 μg/L, respectively, whereas the content of aldehydes decreased (69.48 μg/L) compared with those before fermentation. A total of volatile components were identified in the tea infusion fermented by acetic acid bacteria, in which the contents of alcohols and ketones increased respectively to 178.33 and 14.15 μg/L, while the content of olefins decreased to 19.37 μg/L relative to those before fermentation. A total of 32 volatile components were identified in the tea infusion fermented by lactic acid bacteria, in which the contents of alcohols, esters and ketones increased respectively to 90.70, 53.91 and 19.82 μg/L, while the content of olefins decreased to 10.89 μg/L relative to those before fermentation. This study showed that lactic acid bacterial fermentation could improve the aroma acceptability of black tea infusion, mainly because the intensity of fruity aroma was enhanced with increasing amounts of alcohols, esters and ketones. The results of this study provide a theoretical rationale for applying fermentation to improve the flavor of black tea products.

Key words: black tea infusion; fermentation; volatile components; gas chromatography-mass spectrometry; sensory evaluation