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

Abstract

Background: 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. Objective: 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)]. Methods: 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. Results: 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%). Conclusions: 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. Highlights: 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.