theanine and gallocatechol

Sweet aftertaste (Huigan) is a sensation perceived after drinking tea, and lasts in the mouth and throat, leading to salivation for an extended period of time. The study aimed to reveal the underpinning mechanisms of Huigan and the its influencing factors. Tribology approach was applied to this study in conjunction with sensory analysis and other physiology assessments. Tea compounds of commercial interest were selected for the study. Preliminary sensory tests of 24 subjects were carried out to evaluate the Huigan intensity of these tea compounds. Based on these tests, 12 subjects were selected and divided into two groups, each with 6 subjects: sensitive subjects and non-sensitive subjects. In vitro tribology measurements were made for samples prepared either prepared as 1:1 mixtures of tea compound solution and human whole saliva or expectorated tea compound solutions along with the saliva which were collected from the subjects after oral processing. The Huigan intensity perceived by the sensitive group was found to be highly correlated with the friction coefficient measured, especially at the sliding speeds lower than 0.5 mm/s.

Topics: Adult; Catechin; China; Flavonoids; Friction; Glutamates; Humans; Polyphenols; Saliva; Sensation; Taste Perception; Tea; Young Adult

Although specialized metabolite distributions in different tea (Camellia sinensis) tissues has been studied extensively, little is known about their within-tissue distribution owing to the lack of nondestructive methodology. In this study, desorption electrospray ionization imaging mass spectrometry was used to investigate the within-tissue spatial distributions of specialized metabolites in tea. To overcome the negative effects of the large amount of wax on tea leaves, several sample preparation methods were compared, with a Teflon-imprint method established for tea leaves. Polyphenols are characteristic metabolites in tea leaves. Epicatechin gallate/catechin gallate, epigallocatechin gallate/gallocatechin gallate, and gallic acid were evenly distributed on both sides of the leaves, while epicatechin/catechin, epigallocatechin/gallocatechin, and assamicain A were distributed near the leaf vein. L-Theanine was mainly accumulated in tea roots. L-Theanine and valinol were distributed around the outer root cross-section. The results will advance our understanding of the precise localizations and in-vivo biosyntheses of specialized metabolites in tea.

Topics: Camellia sinensis; Catechin; Gallic Acid; Glutamates; Plant Leaves; Plant Roots; Polyphenols; Spectrometry, Mass, Electrospray Ionization

Topics: Amino Acids; Camellia sinensis; Catechin; Chromatography, Liquid; Glutamates; Glycosides; Kaempferols; Metabolome; Metabolomics; Plant Leaves; Plant Shoots; Tandem Mass Spectrometry

Use of covering cultivation to shade tea (Camellia sinensis L.) trees to produce high-quality, high-priced green tea has recently increased in Japan. Knowledge of shading effects on morphological and color traits and on chemical components of new tea shoots is important for product quality and productivity. We assessed these traits of tea shoots and their relationships under covering cultivation of various radiation intensities.. Leaf thickness, leaf mass per area, and leaf density of new tea leaves were smaller under covering culture than under open-field culture. SPAD values and chlorophyll contents were larger under covering culture than under open culture. The derived exponential equation for estimating chlorophyll contents from SPAD values was improved by considering leaf thickness. Covering culture decreased epicatechin and epigallocatechin contents, and increased theanine and caffeine contents. Principal component analysis on shoot and leaf traits indicated that leaf mass per area, chlorophyll, epicatechin, and epigallocatechin contents were strongly associated with shading effects.. The morphological traits, color traits, and chemical components of new tea shoots and leaves varied depending on radiation intensity, shoot growth, and cropping season. These findings are useful for covering cultivation with high quality and high productivity in tea gardens. © 2018 Society of Chemical Industry.

Topics: Caffeine; Camellia sinensis; Catechin; Chlorophyll; Color; Crop Production; Glutamates; Japan; Phenotype; Plant Leaves; Seasons; Tea

This is the first study to use chemometric methods to differentiate among 21 cultivars of Camellia sinensis from China and between leaves harvested at different times of the year using 30 compounds implicated in the taste and quality of tea. Unique patterns of catechin derivatives were observed among cultivars and across harvest seasons. C. sinensis var. pubilimba (You 510) differed from the cultivars of C. sinensis var. sinensis, with higher levels of theobromine, (+)-catechin, gallocatechin, gallocatechin gallate and theasinensin B, and lower levels of (-)-epicatechin, (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), respectively. Three cultivars of C. sinensis var. sinensis, Fuyun 7, Qiancha 7 and Zijuan contained significantly more caffeoylquinic acids than others cultivars. A Linear Discriminant Analysis model based on the abundance of 12 compounds was able to discriminate amongst all 21 tea cultivars. Harvest time impacted the abundance of EGC, theanine and afzelechin gallate.

Topics: Camellia sinensis; Catechin; China; Flavonoids; Glutamates; Phenols; Plant Extracts; Plant Leaves; Seasons; Xanthines

Theanine, an amino acid in tea, has significant anti-stress effects on animals and humans. However, the anti-stress effects of drinking green tea have not yet been elucidated.. The present study aimed to explore anti-stress effects of green tea and roles of tea components in a mouse model of psychosocial stress.. We examined anti-stress effects of three types of green teas, theanine-rich "Gyokuro", standard "Sencha", and Sencha with lowered caffeine (low-caffeine green tea). Furthermore, the roles of tea components such as caffeine, catechins, and other amino acids in anti-stress effects were examined.. To prepare low-caffeine green tea, plucked new tea leaves were treated with a hot-water spray. Mice were psychosocially stressed from a conflict among male mice under confrontational housing. Mice consumed each tea that was eluted with room temperature water ad libitum. As a marker for the stress response, adrenal hypertrophy was compared with mice that ingested water.. Caffeine was significantly lowered by spraying hot-water on tea leaves. While epigallocatechin gallate (EGCG) is the main catechin in tea leaves, epigallocatechin (EGC) was mainly infused into water at room temperature. Adrenal hypertrophy was significantly suppressed in mice that ingested theanine-rich and low-caffeine green tea that were eluted with water at room temperature. Caffeine and EGCG suppressed the anti-stress effects of theanine while EGC and arginine (Arg) retained these effects.. These results suggest that drinking green tea exhibits anti-stress effects, where theanine, EGC and Arg cooperatively abolish the counter-effect of caffeine and EGCG on psychosocial stress induced adrenal hypertrophy in mice.

Topics: Adrenal Glands; Animals; Arginine; Caffeine; Camellia sinensis; Catechin; Drug Interactions; Glutamates; Hypertrophy; Male; Mice; Phytotherapy; Plant Extracts; Stress, Psychological; Tea; Temperature; Water

The effects of climatic conditions on green tea metabolites in three different growing areas of Jeju Island, South Korea, were investigated through global metabolite profiling by (1)H nuclear magnetic resonance (NMR) spectroscopy. Pattern recognition methods, such as principal component analysis (PCA) and orthogonal projection on latent structure-discriminant analysis (OPLS-DA), revealed clear discriminations of green teas from the three different growing areas. Variations of theanine, isoleucine, leucine, valine, alanine, threonine, glutamine, quinic acid, glucose, epicatechin (EC), epigallocatechin (EGC), epigallocatechin-3-gallate (EGCG), and caffeine levels were responsible for the discriminations. Green teas grown in an area with high temperature, long sun exposure time, and high rainfall had higher levels of theanine but lower levels of isoleucine, leucine, valine, alanine, EC, EGC, EGCG, and caffeine than those grown in areas with relatively low temperature, short sun exposure time, and low rainfall. These results indicate that high temperature, long sun exposure, and high preciptation stimulate theanine synthesis in green tea during the spring season. This study highlights how metabolomics coupled with multivariate statistical analysis can illuminate the metabolic characteristics of green tea associated with climatic variables, thereby allowing for the assessment of quality strategy in green tea production.

Topics: Amino Acids; Caffeine; Camellia sinensis; Catechin; Climate; Discriminant Analysis; Glutamates; Magnetic Resonance Spectroscopy; Metabolomics; Multivariate Analysis; Republic of Korea