Exploration on appropriate brewing conditions of Xanthoceras sorbifolium bud black tea: Insight from nutrient-flavor profiles, antioxidant efficacy and GC-IMS-electronic sensing analysis.

The brewing conditions are critical factors influencing the nutrient, flavor characteristic and bioactive components of tea. In this work, the effects of different brewing conditions on the nutritional composition, flavor profile, sensory characteristics, and antioxidant capacity of Xanthoceras sorbifolium bud black tea (XBT) were investigated. Results demonstrated that brewing at 90 °C/30 min (XBTI-1) represented the optimal condition for high-quality XBT, which produced relatively high flavonoid, soluble sugar, and total polyphenol contents, with well-balanced nutrients, intense umami, and excellent infusion richness. Moreover, 1-octen-3-one, 2-methylpropanal, and 2-methylbutanal were found as flavor markers in 16 key odorants with relative odor activity value (ROAV >1.0) from 75 volatile organic compounds in tea infusion. Furthermore, XBTI-1 showed relatively superior antioxidant capacity in vitro, with an Antioxidant Potency Composite index of 0.984. Collectively, 90 °C/30 min is recommended as the ideal brewing condition for XBT.