Aroma dynamic characteristics during the drying process of green tea by gas phase electronic nose and gas chromatography-ion mobility spectrometry

The drying technology plays an important role in aroma quality. Herein, the dynamic change of volatile profiles of green tea under different temperature gradients and duration were analyzed by using gas phase electronic nose (GC-E-Nose) and gas chromatography-ion mobility spectrometry (GC-IMS) combined with multivariate statistical analysis. A total of 33 compounds were identified. Three drying stages could be clearly discriminated from the samples with different drying time, and 20-min-drying was a key transition point. 3-Methylbutanal, isopropyl alcohol, methyl benzoate, and heptanal were found to play an important role in discrimination of the above three stages, basing on variable importance in projection > 1.2 and p < 0.01. The volatile profiles changed dynamically with increasing drying temperature, and the significant change occurred under the temperature of 105 degrees C. In addition, the GC-E-Nose could quickly and effectively characterize the dynamic changes under different drying conditions, and verified and complemented the GC-IMS analysis results. This study provides comprehensive insight into variation in the volatile metabolite profile during the drying process of green tea.