Effects of Different Steeping Temperatures on the Leaching of Aroma Components in Black Tea by SPME-GC-MS Coupled with Chemometric Method.

Black tea is famous for its unique aroma. The analysis of aroma components has attracted considerable attention worldwide because of its complex chemical composition and low concentration. Steeping temperature is one of the most important factors affecting the aroma of black tea. This study aims to evaluate the effects of four steeping temperatures [60, 70, 80, and 95°C (boiling water)]. Two major factors affecting extraction performance, including the type of extraction method [direct headspace injection (HS) and solid-phase microextraction (SPME)] and extraction time (50, 60, and 70 min), were optimized to enrich and analyze the aroma components of Congou black tea by GC-MS. In addition, heuristic evolving latent projection (HELP), an effective chemometric resolution method, was employed to resolve the overlapped peaks. A total of 83 aroma components were tentatively identified by GC-MS, such as alcohol (42.06-50.52%), aldehyde (12.09-15.97%), and hydrocarbon (4.79-15.32%). Linalool and its oxides (25.49-36.24%) were the most abundant aroma components, followed by geraniol (2.55-8.54%), methyl salicylate (1.84-9.50%), and nerol (1.93-4.41%). The black tea steeped at 95°C smelled more pleasant with mild green, roast, and fruity aroma. Moreover, at 80°C, the tea had sweeter fragrance with floral aroma, while steeping at 60 and 70°C resulted in more reinforced woody and fatty aroma. A total of 83 aroma components of black tea were tentatively identified by SPME-GC-MS. The overlapped peaks were resolved by the HELP method. Aroma characteristics of different steeping temperatures were revealed.