Fixation method shapes jasmine tea aroma quality by modifying tea base structure

Green tea fixation shapes tea base structure and ultimately influences floral volatile adsorption during jasmine scenting, yet the underlying structural basis remains unclear. This study comparatively evaluated the effects of roller, steam, and microwave fixation on tea base structure and floral volatile adsorption through structural characterization, aroma analysis, and sensory evaluation. Microwave-fixed tea bases exhibited the highest mesopore proportion, with a dominant pore system distributed within 2-50 nm and the largest specific surface area (0.2178 m²/g), which was conducive to floral volatile adsorption and retention during scenting. After baseline correction using corresponding unscented tea bases, microwave-fixed samples showed greater enrichment of characteristic jasmine aroma compounds, including linalool, geraniol, benzyl acetate, (Z)-3-hexen-1-ol, and indole, among the 152 volatile compounds. Correlation analysis revealed significant positive associations between specific surface area, porosity, mesopore proportion, and floral volatile enrichment. In contrast, roller- and steam-fixed tea bases showed lower mesopore proportions and smaller specific surface areas (0.1258 and 0.0288 m²/g, respectively), resulting in reduced floral volatile adsorption. Consequently, jasmine tea prepared from microwave-fixed tea bases achieved the highest sensory scores for floral intensity, purity, persistence, and overall harmony. The study bridged tea base microstructure and floral volatile adsorption, providing a foundation for optimizing fixation processes to improve jasmine tea aroma quality.