GC/QQQ coupling with metabolomics for selection of predicator of tea fermentation.

Fermentation is the most crucial process for manufacture of black tea. Signature components were desired for the establishment of accurate prediction of fermentation degree. In this study, finished black teas were prepared using leaves that had been fermented for various times, and sensory quality evaluation was performed. Tracking analysis of volatiles during fermentation was conducted to discriminate the iconic compounds. On the basis of both the sensory evaluation results and the enzymatic oxidation traits of fermentation, the ratio of ß-cyclocitral to γ-pylpyrone was proposed as an indicator. A positive correlation was observed between this ratio and the sensory score of finished black tea with varied duration of fermentation, and the correlation coefficient was 0.78. Furthermore, widely plant-targeted metabolomics was applied to cognize the fermentation. Comparative analysis of metabolites was conducted by category, and special attention was paid to flavonoids and terpenes. Significant metabolic differences emerged discriminatively. The results would be useful for intelligent modulation of the manufacture of black tea.

Impact of tea leaves categories on physicochemical, antioxidant, and sensorial profiles of tea wine.

Introduction: Tea is the main raw material for preparing tea wine. Methods: In this research, four types of tea wine were prepared using different categories of tea leaves, including green tea, oolong tea, black tea, and dark tea, and the comparative study looking their physicochemical, sensorial, and antioxidant profiles were carried out. Results: The dynamic changes of total soluble solids, amino acids and ethanol concentrations, and pH were similar in four tea wines. The green tea wine (GTW) showed the highest consumption of total soluble solids and amino acids, and produced the highest concentrations of alcohol, malic, succinic, and lactic acid among all tea wines. The analysis of volatile components indicated the number and concentration of esters and alcohols increased significantly after fermentation of tea wines. GTW presented the highest volatile concentration, while oolong tea wine (OTW) showed the highest number of volatile compounds. GTW had the highest total catechins concentration of 404 mg/L and the highest ABTS value (1.63 mmol TEAC/mL), while OTW showed the highest DPPH value (1.00 mmol TEAC/mL). Moreover, OTW showed the highest score of sensory properties. Discussion: Therefore, the types of tea leaves used in the tea wine production interfere in its bioactive composition, sensorial, and antioxidant properties.

Recognition of Gallotannins and the Physiological Activities: From Chemical View.

Gallotannins, characterized with the glycosidic core and galloyl unit, are seemed as vital components of hydrolyzable tannins. Benefit from the more and more discoveries of their bioactivities and edibility, application of gallotannins in food industry, pharmacy industry, and other fields is increasing. Inheriting previous study achievements, chemical structure of gallotannins was illustrated and degradation as well as synthetic routes to gallotannins were summarized. On this basis, distribution in the nature also including the distinction of gallotannins was discussed. More than that, activities involving in antioxidant, anti-inflammatory, enzyme inhibitions, protein binding, and so on, as well as applications in the field of food industry, biopharmaceutical science, agricultural production, etc., were combed. Finally, improvement of bioavailability, chemical modification of the structure, and accurate determination of new gallotannins were pointed out to be the orientation in the future.

Ag2O-mediated Tandem Reaction between Terminal Alkyne and o-Iodibenzoic Acid: Construction of 3-Ethylideneisobenzofuran-1(3H)-ones.

Taking aryl propargyl ether and o-iodibenzoic acid as substrates, a series of aryl cyclolactones bearing an exocyclized C=C bond were constructed with moderate to good yields. Diverse substituent groups could be tolerant in the reaction, which indicated excellent compatibility of the reaction. In this tandem reaction, Ag2O was employed as the media and Et3N was screened as the base to facilitate the reaction. A concise mechanism was proposed on the basis of the expansion of the substrates and theoretical analysis. Sonogashira type coupling coupled with intramolecular nucleophilic addition in one pot to construct the product, 3-ethylideneisobenzofuran-1(3H)-one.

Research progress on theaflavins: efficacy, formation, and preparation.

Background: Theaflavins (TFs) are a category of natural compounds characterized with the benzotropolone skeleton. The prominent benefits of TFs have been well documented. Amount of research were conducted and excellent achievements were disclosed during the past years. However, as far as we know, there is no comprehensive review about TFs. Scope and approach: This review summarized the recent research progress. The activity of TFs on anti-oxidation, anti-mutagenicity, hypolipidemic, anti-inflammatory, anti-cancer, anti-viral effect as well as the epidemiological cure were sorted. Converging pioneer literature and deduction, the underlying formation mechanism of TFs was proposed. Subsequently, acquisition of TFs was pointed out to be the fundament for further research. Accelerated by enzyme, bio-synthesis of TFs were reviewed simultaneously. At the end, employing modern analysis instrument and technology, isolations of TFs were enumerated. Key findings and conclusions: Structure of the skeleton as well as functional groups were paramount related with the bio-activity of TFs. Meanwhile, oxidation pathway of two catechin molecules to form TFs were hypothesized. Also, ascertainment of the several therapeutic efficiency of the family members of TFs would be the next step in the future.