Analysis of the Changes in Volatile Components During the Processing of Enshi Yulu Tea.

Volatile constituents are critical to the flavor of tea, but the changes in Enshi Yulu tea during the processing have not been clearly understood. Using headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) techniques, we analyze the aroma components of Enshi Yulu tea and changes in them during the processing stages. In total, 242 volatile compounds were identified.

Effects of Microbial Proteins on Qingzhuan Tea Sensory Quality during Pile Fermentation.

To determine the effects of microbial proteins on Qingzhuan tea sensory quality during tea pile fermentation, tea leaf metabolomic and microorganism proteomic analyses were performed. In total, 1835 differential metabolites and 443 differentially expressed proteins of the microorganisms were identified. Correlation analysis between metabolomics and proteomics data revealed that the levels of microbial proteins EG II and CBH I cellulase may play important roles in cell wall construction and permeability, which were crucial for the interaction between tea leaves and microorganisms.

Insights into the effects of fixation methods on the sensory quality of straight-shaped green tea and dynamic changes of key taste metabolites by widely targeted metabolomic analysis.

Fresh leaves of Echa 1 were fixed by roller, steam/hot air and light-wave, and the effects of the three fixation methods on the chemical characteristics of straight-shaped green teas (GTs) were studied by widely targeted metabolomic analysis. 1001 non-volatile substances was identified, from which 97 differential metabolites were selected by the criteria of variable importance in projection (VIP) > 1,  < 0.05, and |log(fold change)| > 1.

Digital Prediction of the Purchase Price of Fresh Tea Leaves of Enshi Yulu Based on Near-Infrared Spectroscopy Combined with Multivariate Analysis.

In this study, near-infrared spectroscopy (NIRS) combined with a variety of chemometrics methods was used to establish a fast and non-destructive prediction model for the purchase price of fresh tea leaves. Firstly, a paired -test was conducted on the quality index (QI) of seven quality grade fresh tea samples, all of which showed statistical significance ( < 0.05).

Microbial Diversity and Characteristic Quality Formation of Qingzhuan Tea as Revealed by Metagenomic and Metabolomic Analysis during Pile Fermentation.

In order to analyze the changes in the microbial community structure during the pile fermentation of Qingzhuan tea and their correlation with the formation of quality compounds in Qingzhuan tea, this study carried out metagenomic and metabolomic analyses of tea samples during the fermentation process of Qingzhuan tea. The changes in the expression and abundance of microorganisms during the pile fermentation were investigated through metagenomic assays. During the processing of Qingzhuan tea, there is a transition from a bacterial dominated ecosystem to an ecosystem enriched with fungi.

Dynamic Changes in Non-Volatile Components during Steamed Green Tea Manufacturing Based on Widely Targeted Metabolomic Analysis.

Steamed green tea has unique characteristics that differ from other green teas. However, the alteration patterns of non-volatile metabolites during steamed green tea processing are not fully understood. In this study, a widely targeted metabolomic method was employed to explore the changes in non-volatile metabolites during steamed green tea processing.

Dynamic Changes in Volatile Compounds of Shaken Black Tea during Its Manufacture by GC × GC-TOFMS and Multivariate Data Analysis.

Changes in key odorants of shaken black tea (SBT) during its manufacture were determined using headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography−time-of-flight mass spectrometry (GC × GC−TOFMS) and multivariate data analysis. A total of 241 volatiles was identified, comprising 49 aldehydes, 40 esters, 29 alcohols, 34 ketones, 30 aromatics, 24 alkenes, 17 alkanes, 13 furans, and 5 other compounds. A total of 27 volatiles had average relative odor activity values (rOAVs) greater than 1, among which (E)-β-ionone, (E,Z)-2,6-nonadienal, and 1-octen-3-one exhibited the highest values.

Identification of aroma-active compounds responsible for the floral and sweet odors of Congou black teas using gas chromatography-mass spectrometry/olfactometry, odor activity value, and chemometrics.

Background: Floral and sweet odors are two typical characteristic aromas of Congou black tea, but their aroma-active compounds are still unclear. Characterizing the key aroma-active compounds can provide a theoretical foundation for the practical aroma quality evaluation of Congou black tea and directional processing technology of high-quality black tea with floral or sweet odors. Gas chromatography-olfactometry (GC-O) combined with odor activity value (OAV) is often used to screen key aroma-active substances, but the interaction between aroma components and their impact on the overall sensory quality is ignored.

Kojic Acid Showed Consistent Inhibitory Activity on Tyrosinase from Mushroom and in Cultured B16F10 Cells Compared with Arbutins.

Kojic acid, β-arbutin, α-arbutin, and deoxyarbutin have been reported as tyrosinase inhibitors in many articles, but some contradictions exist in their differing results. In order to provide some explanations for these contradictions and to find the most suitable compound as a positive control for screening potential tyrosinase inhibitors, the activity and inhibition type of the aforementioned compounds on monophenolase and diphenolase of mushroom tyrosinase (MTYR) were studied. Their effects on B16F10 cells melanin content, tyrosinase (BTYR) activity, and cell viability were also exposed.

Adsorption Equilibrium and Thermodynamics of Tea Theasinensins on HP20-A High-Efficiency Macroporous Adsorption Resin.

The separation and preparation of theasinensins have been hot spots in the field of tea chemistry in recent years. However, information about the mechanism of efficient adsorption of tea theasinensins by resin has been limited. In this study, the adsorption equilibrium and thermodynamics of tea theasinensins by a high-efficiency macroporous adsorption HP20 resin were evaluated.