Application of chemical composition and infusion colour difference analysis to quality estimation of jasmine‐scented tea

Abstract

Infusion chemical composition, colour difference indicators and volatile constituents of seventeen jasminescented tea samples and their correlation with sensory total quality score given by tea-tasting panel were studied by techniques of HPLC, colour difference metre and gas chromatograph. Spearman's linear correlation analysis showed that concentration of nitrogen, caffeine, catechin, epicatechin, catechin gallate, total catechins, terpineol, nerol and infusion light-black indicator DL, yellow-blue indicator Db, total colour difference indicator DE were significantly correlated with sensory total quality score, respectively. Regression of the total quality score upon twelve components extracted from thirty-six tested indicators by principal component analysis could properly estimate total quality score of two jasmine-scented tea samples which were not included in the seventeen samples used to construct the regression model.

Analysis of chemical components in green tea in relation with perceived quality, a case study with Longjing teas

“…The composition of free amino acids was measured by HPLC (Waters 600; Waters Corp., Milford, MA, USA) with AccQ Tag column (3.9 mm × 150 mm) and a fluorescence detector after derivatisation with AccQ‐Fluor Reagent Kit following the manufacturer’s protocol (Waters Corporation, 1996). Contents of total amino acid in the tea infusions were determined by a spectra‐photometric method (Liang et al ., 2007). The composition of caffeine and catechins in the extract was determined with a HPLC system (Waters 590; Waters Corp.) equipped with a Hypersil ODS2 C 18 column (5 μm, 4.6 mm × 250 mm, 35 °C) at 280 nm as previously described (Su et al ., 2003).…”

“…Concentrations of caffeine and catechins were quantified by their peak areas against those of standards prepared from authentic compounds. Total nitrogen was measured by Kjeldahl digestion method (Liang et al , 2007).…”

Analysis of chemical components in oolong tea in relation to perceived quality

“…Composition and perceived quality of Oolong tea K. Wang et al quality and category of teas (Liang et al, 2003(Liang et al, , 2005b(Liang et al, , 2007Le Gall et al, 2004). To select the most useful indicators, principal component analysis (PCA) was applied to screen the data set.…”

Comparison of Phenolic Compounds and Taste of Chinese Black Tea

“…The taste-sensing system required special Sensory evaluation Three grammes of tea sample were infused with 150 mL freshly boiled water for 5 min. Perceived quality score was blindly assessed according to a standardized procedure by a tea-tasting panel consisted of six professional panelists (Liang et al, 2007;Wang & Ruan, 2009). Procedure of sensory evaluation is given as follows (Hui et al, 2004;Wang and Ruan, 2009).…”

“…Multivariate analysis on chemical components provides useful methodology to distinguish the origin, quality and category of teas (Liang et al, 2003(Liang et al, , 2007Le Gall et al, 2004;Wang et al, 2010).…”