Characterization of the Key Odorants in a High-Grade Chinese Green Tea Beverage (Camellia sinensis; Jingshan cha) by Means of the Sensomics Approach and Elucidation of Odorant Changes in Tea Leaves Caused by the Tea Manufacturing Process

Abstract

Sensory-guided analysis of the volatile fraction isolated from a freshly prepared green tea beverage (Camellia sinensis; type Jingshan cha) revealed 58 odor-active compounds after application of an aroma extract dilution analysis. Among them, 3methylnonane-2,4-dione, (Z)-1,5-octadien-3-one, 3-(methylthio)propanal, trans-4,5-epoxy-(E)-2-decenal, methanethiol, dimethyl sulfide, and indole appeared with the highest flavor dilution factors. A quantitation of 42 aroma compounds by means of stable isotope dilution assays followed by the calculation of odor activity values (OAV; ratio of concentration to odor detection threshold) showed 27 key aroma compounds with OAVs ≥ 1. By far, the highest OAV of 458 was calculated for the asparagus-like/putrid smelling dimethyl sulfide followed by (E,E)-2,4-heptadienal (46). Finally, an aqueous recombinate containing all 27 aroma compounds in the concentrations measured in the beverage successfully mimicked the overall aroma profile of the tea infusion. Quantitative measurements were then performed on authentic tea material to elucidate changes in key aroma compounds during each processing step (fresh leaves, withering, pan-firing, rolling, and drying). The results indicated that dimethyl sulfide, one of the important aroma compounds, was significantly increased by withering of the fresh leaves, however, a major part was lost during drying. Linalool, geraniol, and hexanal showed the highest concentrations in the fresh tea leaves, while significantly lower concentrations were measured in the final tea. The same was observed for all lipid degradation products, such as (E,E)-2,4heptadienal.

Characterization of the effect of cis-3-hexen-1-ol on green tea aroma

“…In the existing research, the aroma reconstitution of tea was often carried out with pure water as the substrate 29 , which is because the tea drinking way is to brew with boiling water. However, the results of this experiment and the reported recombination experiments showed that there were some differences between the reconstitution solution and the tea samples, which may came from not only the qualitative and quantitative detection errors, but also the interference of non-volatile substances in tea.…”

Evaluation of the daytime tropospheric loss of 2-methylbutanal

“…It is known that 2 MB is formed during the fermentation and drying processes of cocoa beans (Utrilla-Vázquez et al, 2020), the manufacturing process of tea leaves (e.g. Camellia Sinensis, Flaig et al, 2020), and as a consequence of the stress suffered by grapevine leaves due to drought (Griesser et al, 2015). Besides, this aldehyde is emitted into the atmosphere from wildland fires (Urbanski et al, 2008) and many industrial activities, such as poultry rendering operations during which animal by-products are processed (Kolar and Kastner, 2010).…”

Sensomics-Assisted Aroma Decoding of Pea Protein Isolates (Pisum sativum L.)

“…Over the last years, the Sensomics concept was successfully adopted to identify many KFO in different food matrices, such as in Chinese green tea [12], in Styrian pumpkin seed oil [13], or in raw licorice [14], for instance. By applying the recently described "unified flavor quantitation", we could advantageously supplement the Sensomics approach by a fast sample preparation, easy handling, and quick UHPLC-MS/MS measurements [15].…”