Insight into volatile metabolites and key odorants in black teas processed from Jianghua Kucha tea germplasm (Camellia sinensis var. assamica cv. Jianghua).

Jianghua Kucha (JHKC) is an ancient tea germplasm, which presents a high value for resource utilization but was less developed in aroma research. In this study, volatile metabolites in fresh leaves and corresponding black teas of JHKC, along with odorants of JHKC black teas were systematically investigated using stir-bar sorptive extraction in combination with gas chromatography-mass spectrometry (GC-MS) and GC-olfactometry/MS (GC-O/MS) technologies. A total of 128 and 135 volatile compounds were identified in fresh leaves and black teas, respectively, along with 13 key differential volatile components derived from fatty acids, pigments, glycoside precursors, and the terpene pathway.

Comprehensive comparison of aroma profiles and chiral free and glycosidically bound volatiles in Fujian and Yunnan white teas.

The Fujian and Yunnan provinces in China are the most representative origins of white tea. However, the key differences in the chemical constituents of the two white teas have rarely been revealed. In this study, a comprehensive comparison of the aroma profiles, chiral volatiles, and glycosidically bound volatiles (GBVs) in Fujian and Yunnan white teas was performed, and 174 volatiles and 28 enantiomers, including 22 volatiles and six GBVs, were identified.

Aromatic profiles and enantiomeric distributions of chiral odorants in baked green teas with different picking tenderness.

Suitable picking tenderness is an essential prerequisite for manufacturing tea. However, the influence of picking tenderness of fresh tea leaves on the aromatic components is still unclear. In this study, aromatic profiles and chiral odorants in fresh tea leaves and corresponding baked green teas with five levels of tenderness of two representative cultivars were analysed using stir bar sorptive extraction-gas chromatography-mass spectrometry.

Assessment of the contribution of chiral odorants to aroma property of baked green teas using an efficient sequential stir bar sorptive extraction approach.

Chiral volatile compounds are known to be distributed in teas at various enantiomeric ratios. However, the performance of each enantiomer, including aroma characteristics, aroma intensities, and contribution to the overall flavor of tea, is still unclear. In this study, aroma characteristics and intensities of 38 volatile enantiomers in standards and baked green teas with chestnut-like aroma and clean aroma were evaluated by an efficient sequential headspace-stir bar sorptive extraction (seq-HS-SBSE) approach combined with the enantioselective gas chromatography-olfactometry/mass spectrometry (Es-GC-O/MS) technique.

Enantiomeric distributions of volatile lactones and terpenoids in white teas stored for different durations.

Precise identification of the compounds characteristic to stored white teas is urgently needed as these products have unique flavors and health benefits that improve with storage duration. Owing to the potential applications in food quality discrimination, specific regularities between the enantiomeric distributions of 23 volatile lactones and terpenoids and storage durations of white teas were expected and investigated by enantioselective gas chromatography-mass spectrometry (Es-GC-MS) combined with multivariate statistical analysis. High correlation coefficients (-0.

Characterization of the key aroma compounds in Longjing tea using stir bar sorptive extraction (SBSE) combined with gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), odor activity value (OAV), and aroma recombination.

Longjing tea is the most famous premium green tea, and is regarded as the national tea in China, with its attractive aroma contributing as a prime factor for its general acceptability; however, its key aroma compounds are essentially unknown. In the present study, volatile compounds from Longjing tea were extracted and examined using stir bar sorptive extraction (SBSE) combined with gas chromatography-mass spectrometry (GC-MS). Data obtained from the present study revealed that 151 volatile compounds from 16 different chemical classes were identified by GC-MS analysis.

Identification and quantification of key odorants in the world's four most famous black teas.

Keemun, Assam, Darjeeling and Ceylon black teas are honored as the world's four most famous black teas, and their excellent aroma qualities are well received by people around the world. In this study, aroma components in these four types of teas were analyzed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) and gas chromatography-olfactometry (GC-O) technologies. A total of 42 aroma-active compounds were ultimately identified, especially benzeneacetaldehyde, geraniol, (Z)-3-hexen-1-yl hexanoate, trans-β-ionone, cis-linalool oxide (pyranoid), hotrienol, and methyl salicylate presented the strongest aroma strengths with pleasant scents in all tested teas.

The enantiomeric distributions of volatile constituents in different tea cultivars.

Although the enantiomeric distribution of chiral volatiles presents great potential in discrimination of tea cultivars and their geographic origins, this area has received little attention. Thus, we herein aimed to determine the relationships between tea cultivars and the enantiomeric distributions of their chiral volatile constituents. Headspace solid-phase microextraction (HS-SPME) and enantioselective gas chromatography-mass spectrometry (Es-GC-MS) were employed to quantify 15 volatile components in 22 tea cultivars from different locations within China.

Identification of key odorants responsible for chestnut-like aroma quality of green teas.

A chestnut-like aroma is widely considered an important indicator of an excellent-quality green tea; however, the key odorants responsible for chestnut-like aroma have never been systematically studied and remain unknown. In this study, the aroma components of green teas and Chinese chestnuts were analyzed using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS), and 58 compounds were identified as common aroma components among green teas, boiled Chinese chestnuts, roasted Chinese chestnuts and raw Chinese chestnuts. Subsequently, 17 volatiles, including 3-methylbutanal, (E)-3-penten-2-one, ethylbenzene, heptanal, benzaldehyde, 2-pentylfuran, octanal, benzeneacetaldehyde, (E)-2-octenal, (E,E)-3,5-octadien-2-one, linalool, nonanal, (E)-2-nonenal, decanal, (Z)-hex-3-en-1-yl hexanoate, trans-β-ionone and (E)-nerolidol, were identified as the key odorants responsible for chestnut-like aroma based on the odor activity value (OAV) calculation method.

Phytochemical profiles and antioxidant activities of Chinese dark teas obtained by different processing technologies.

Dark teas are rich in secondary metabolites, such as phenolics and flavonoids, which have been suggested to be associated with their health benefits. In this study, the concentrations of tea polyphenols, tea pigments, catechins, flavonoids, alkaloid, and volatile components in 44 dark tea samples, including Pu-erh, Fuzhuan and Liubao teas, were systematically examined. Among the samples tested, Pu-erh tea contained the highest total flavonoid content (5.

Enantiomeric and quantitative analysis of volatile terpenoids in different teas (Camellia sinensis).

Volatile terpenoids play important roles in the formation of tea aroma quality due to their pleasant scents and low odor thresholds. Most volatile terpenoids contain stereogenic centers, which results in various stereo distributions of their enantiomers and diastereoisomers in different types of tea. However, the distribution characteristics of terpenoid enantiomers in teas were still unclear, which poses an obstacle to the scientific understanding of tea aroma.

Transcriptional responses and flavor volatiles biosynthesis in methyl jasmonate-treated tea leaves.

Background: Tea (Camellia sinensis) has long been consumed worldwide for its amazing flavor and aroma. Methyl jasmonate (MeJA), which acts as an effective elicitor among the plant kingdom, could mostly improve the quality of tea aroma by promoting flavor volatiles in tea leaves. Although a variety of volatile secondary metabolites that contribute to aroma quality have been identified, our understanding of the biosynthetic pathways of these compounds has remained largely incomplete.

Cloning of a caffeoyl-coenzyme A O-methyltransferase from Camellia sinensis and analysis of its catalytic activity.

Epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3"Me) present in leaves of Camellia sinensis has many beneficial biological activities for human health. However, EGCG3"Me occurs naturally in tea leaves in extremely limited quantities. Finding an enzyme from C.

Aroma changes of black tea prepared from methyl jasmonate treated tea plants.

Methyl jasmonate (MeJA) was widely applied in promoting food quality. Aroma is one of the key indicators in judging the quality of tea. This study examined the effect of exogenous MeJA treatment on tea aroma.