Maillard reaction inducing amino acids degradation can adjust the flavour characteristic of black tea

Drying is the step that is to be used to adjust and control the formation of flavour and quality in black tea processing. In the present work, the comprehensive two-dimensional gas chromatography with mass spectrometry (GC × GC-MS) and gas chromatography olfactometry with mass (GC-O-MS) were used to determine the dynamic change of the volatile compounds in black tea during drying at 90, 120, 150 °C for 1 h. Results showed that the ratio of esters and aldehydes largely declined when temperature was elevated from 90 °C to 150 °C, while the ratio of heterocycles was increased to 22.4 % from 16.5 %. A total of 15 key aroma activity volatiles were screened out in three temperature dried samples, therein 11 volatiles were connected with the Maillard reaction, meaning these volatiles were highly relevant to the degradation of amino acids during the drying process. We detected that 21 amino acids were decreased with enhanced temperature and extended the drying time, which promoted the Maillard-derived volatiles formation. Therefore, it was suggested that to control the degradation of amino acids adjust the flavour profiles of black tea by changing the drying temperature and time.