Effect of Oxygen Concentration in Fermentation on Black Tea Quality and Optimization of Oxygen-enriched Fermentation Process

Fermentation is a critical process of black tea quality formation and oxygen is the key factor affecting the fermentation, so it is important to analyze the effect of oxygen in fermentation on the quality and metabolites of black tea. One bud and two leaves of 'Longjing 43' tea varieties were used as materials for low oxygen fermentation (5%) , natural fermentation (21%) and oxygen-enriched fermentation (36%) treatments, and the effects of oxygen concentration on sensory quality, non-volatile and volatile metabolites of black tea were analyzed by sensory evaluation combined with gas chromatography-mass spectrometry (GC-MS) and ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS), and the parameters of oxygen-enriched fermentation of black tea were optimized by single factor combined with response surface analysis. Results showed that oxygen-enriched fermentation could significantly improve the taste and aroma quality of black tea compared with nature fermentation (P