Temperature-dependent regulation of benzeneacetaldehyde formation during black tea drying: Evidence from non-targeted metabolomics and an EGCG-modulated Maillard reaction model.

-phenylalanine via Strecker degradation, is a key floral compound contributing to black tea aroma. However, its thermal transformation upon processing remains unclear. In the present study, non-targeted metabolomics and a phenylalanine-glucose Maillard model regulated by epigallocatechin gallate (EGCG) were employed to elucidate its formation mechanism during drying. Gas chromatography-mass spectrometry identified 441 volatile metabolite features, among which benzeneacetaldehyde showed the highest significance. Multivariate analysis indicated 120 °C as a critical transition temperature for volatile profile evolution. While floral alcohols such as linalool and geraniol declined with temperature, benzeneacetaldehyde remained stable, indicating a continuous thermochemical generation. The Maillard model further confirmed that glucose markedly enhanced benzeneacetaldehyde formation, while EGCG suppressed its accumulation and promoted the retention of non-volatile intermediates. These findings establish benzeneacetaldehyde as a molecular marker linking amino acid degradation, thermal processing, and polyphenol modulation in black tea aroma development.