Chromatographic fingerprinting combined with chemometric methods for the quality evaluation of tea blending using gas chromatography– massspectrometry and gas chromatography–olfactometry

Abstract

Abstract The quality of tea, evaluated by its aroma and taste, determines its market value. It is crucial for enterprises to ensure that desired flavors appear in a certain concentration in the tea products, making it to be well liked in specific consumer groups. In this study, fingerprinting approach combined with multivariate statistical analysis were recommended as a promising prospective methodology in obtaining comprehensive quality control of tea flavor, and optimizing tea blending scheme. Six batches of Chuanhong Congou black raw tea from different batches, Camellia cultivars, plucking season, and grades were selected for blending, and 17 blended tea samples were obtained by uniform mixing design. The chromatographic fingerprints of Chuanhong Congou black tea were established by 59 volatiles and 26 aroma–active compounds using gas chromatography–massspectrometry (GC–MS) combine with gas chromatography–olfactometry (GC–O), respectively. Considering the results of sensory evaluation, volatiles fingerprint was fully reflect the comprehensive aroma quality of Congou black tea. 19 compounds were determined as the key factors for the aroma quality control by partial least squares (PLS) regression combined with the variable importance in the projection (VIP) scores. They were (Z)–3–hexenal, heptaldehyde, benzaldehyde, (E)–linalool oxide (furan type), rose ether, (Z)–5–methyl–2–(1–methylethyl)–cyclohexanon, benzyl acetate, decanal, β–cyclocitral, nerol, citronellol, (Z)–3,7–dimethyloctyl–2,6–dienal, valeric acid Leaf alcohol ester, 1–hexadecene, (E)–3,7–dimethyloctano–2,6–dienal, pentyl caproate, ethyl nonanoate, citronellyl acetate and β–ionone. Due to the existence of sensory differential thresholds and interaction of the aroma compounds, sensory evaluation still played an irreplaceable role in the quality evaluation of tea. The chromatographic fingerprints combined with chemometrics could be considered as an extended methodology in providing directions for optimizing blending scheme.