Characterization of the key aroma compounds in infusions of four white teas by the sensomics approach

White teas are produced in the simple process of withering and drying the tender leaves of the plant Camellia sinensis. Tea aroma created in this way exhibits a unique profile. Studies were carried out on the molecular contributors to the aroma character of the four well-known traditional white teas: Baihaoyingzhen (BHYZ), Baimudan (BMD), Gongmei (GM), and Shoumei (SM). Volatiles of the tea infusions were enriched by solvent partitioning followed by solid-phase extraction (SPE). The highly volatile compounds were captured by headspace solid-phase microextraction (HS SPME). Gas chromatography-olfactometry (GC-O) experiments discovered 37 odor-active components. Quantitation of aroma compounds was achieved using the method of standard addition (SAM). Calculation of odor activity value (OAV) and aroma reconstitution experiments revealed that the aroma profiles of the four white teas were attributed by 15 compounds, although a total of 179 volatile components were found in the extracts. BHYZ had distinct floral, fruity, and sweet characters, while BMD, GM, and SM had stronger woody and fermented notes. The major aroma contributors to the floral and sweet characters were geraniol and linalool for BHYZ and BMD; 2-phenylethanol and phenylacetaldehyde for GM and SM. The compounds produced from amino acid reactions during tea manufacturing, e.g. dimethyl sulfide, 3-methylbutanal, phenylacetaldehyde, etc., formed the basis of fruity and refreshing attributes. Degradation products of glycosides and carotenoids, such as geraniol, linalool, and ionones, contributed to the essential floral and sweet characters of the white teas.

Automated summary

The aroma profiles of four traditional white teas were studied, and it was found that the aroma characteristics were mainly contributed by a few compounds. Floral and sweet characters were produced by geraniol and linalool, while woody and fermented notes were more prominent. Compounds produced from amino acid reactions during tea manufacturing formed fruity and refreshing attributes, and degradation products of glycosides and carotenoids contributed to the essential floral and sweet characters of white teas.