Abstract: Drying is the key manufacturing process for aroma formation of green tea. This work was performed in order to investigate the effect of six different drying methods (tunnel-type far infrared radiation drying, box-type hot air convection drying, chain-plate hot air convection drying, bucket-type hot air convection drying, vibration strip-type conduction drying, and roller-type conduction drying) on the formation of chestnut-like aroma of green tea. A method based on infrared-assisted extraction coupled to headspace solid-phase microextraction followed by gas chromatography-mass spectrometry was developed to analyze the volatile components in green tea. Besides, sensory evaluation and chemical composition analysis were conducted and the obtained data were analyzed using multivariate statistical analysis. The results showed that the chestnut-like aroma of the tea sample obtained by box-type hot air convection drying was the strongest based on sensory evaluation. The aroma score was significantly higher by 3–5 points than that of the samples obtained by the other drying methods, and the overall quality was also better with a sensory score of greater than 90 points. Based on the comparison of the fixation and drying steps in the manufacturing process, obvious regional distribution characteristics were observed before versus after drying. The well-explained variance (R2X = 0.822, R2Y = 0.982) and cross-validation predictive capability (Q2 = 0.856) indicated good feasibility of the model, which confirmed the important influence of drying methods on the formation of chestnut-like aroma. In addition, it was found that among the three heat transfer modes, convection and conduction were more favorable for producing chestnut-like aroma than radiation. These results provide technical guidance for the production and processing of green tea with chestnut-like aroma, and theoretical support for the drying of green tea with chestnut-like aroma.

Key words: drying methods, green tea, chestnut-like aroma, multivariate statistical analysis