Effects of Different Fixation Methods on the Flavor and Quality of ‘Bainiuzao’ Green Tea

This study investigated the effects of three fixation methods including roller fixation (GT), carding machine fixation (LT) and light wave fixation (GB) on the flavor profile of ‘Bainiuzao’ green tea by integrating sensory evaluation, colorimetric analysis, and quantification of key taste and aroma compounds. Results revealed that GB exhibited the highest overall sensory quality with a bright color, a fresh and mellow taste, sweet aftertaste (attributed to higher soluble sugar and amino acid contents), and a tender chestnut-like aroma. GT showed stronger bitterness due to higher contents of ester-type catechins (epigallocatechin gallate (EGCG), epicatechin gallate (ECG)) and caffeine. Eight key taste components, including theanine, glutamic acid, and γ-aminobutyric acid (GABA), were identified using variable importance in projection (VIP) score > 1 as the cutoff. GABA was highlighted as a characteristic marker for differentiating GB from GT and LT. Combining dose-over-threshold factor (Dot) analysis with the quantitative results, caffeine, EGCG, ECG, GABA, and glutamic acid were identified as contributing to the differences in taste among these fixation methods; GT exhibited stronger bitterness, whereas GB and LT had enhanced fresh and brisk taste and sweet aftertaste. A total of 15 key differential compounds were selected (VIP > 1). Relative odor activity value (ROAV) analysis identified trans-linalool oxide, cis-3-hexenyl hexanoate, tert-butanol, linalool, and cis-linalool oxide as the major aroma components across the three fixation methods. Notably, linalool and cis-3-hexenyl hexanoate were likely responsible for the more pronounced chestnut-like aroma in GT and LT compared with GB. The decreasing order of the effects on the flavor and quality of ‘Bainiuzao’ green tea was GB > LT > GT.