Dynamic Variation of Amino Acid Contents and Identification of Sterols in Xinyang Mao Jian Green Tea

Investigation of the quality of Lu'an Guapian tea during Grain Rain period by sensory evaluation, objective quantitative indexes and metabolomics

The harvest date is a crucial factor in determining tea quality. For Lu'an Guapian (LAGP) tea, Grain Rain period (GRP) represents a pivotal phase in the transformation of tea quality. The sensory evaluation, computer vision and E-tongue revealed that the liquor color score, B and G values of tea infusion were increased during GRP, while the astringency, bitterness intensities and the R value of the tea infusion were decreased. Consequently, the tea infusion exhibited a greener hue and the taste became appropriate during GRP. Non-targeted metabolomics revealed that the majority of amino acids and derivatives was reduced during GRP. Furthermore, flavonoids, in particular flavonol glycosides, exhibited considerable variation during GRP. Finally, nine metabolites were identified as markers for quality transformation during GRP by PLS and Random Forest. This study investigated the quality of LAGP teas during GRP and filled the gap in the variation of LAGP tea quality during GRP.

Qualitative and quantitative studies on chemical constituents of Ling-gui-zhu-gan decoction: In vitro and in vivo

Ling-gui-zhu-gan decoction has significant therapeutic effects in the treatment of diseases related to phlegm and fluid retention. In this study, we aimed to qualitatively characterize the chemical constituents of Ling-gui-zhu-gan decoction in vitro and in vivo by HPLC coupled to Fourier transform ion cyclotron resonance MS, and quantitively determine the contents of typical chemical constituents by HPLC method. As a result, a total of 75 chemical constituents were discovered including 37 flavonoids and their glycosides, 20 saponins, 9 sterols, 3 organic acids and their derivatives, 3 lactones, 2 coumarins, and 1 alcohol. Among them, 17 chemical constituents were specifically identified. Subsequently, an HPLC method was established for simultaneous determination of seven chemical constituents. Finally, a total of 40 prototype components were initially detected by HPLC-MS method in the biological samples of rats after their water extract was orally administrated. Among them, 29, 27, 12, and 32 prototype components were detected in plasma, bile, urine, and feces, respectively. Moreover, 34 metabolites, including 16 phase II metabolites, were detected for the first time. In conclusion, this study lays the foundation for the identification of chemical components in vitro and in vivo and the elucidation of the potential pharmacodynamic components of Ling-gui-zhu-gan decoction.

Free amino acids identification and process optimization in greengage wine fermentation and flavor formation

Greengage wine with low alcohol content is increasing in popularity owing to its fruity taste and rich nutrition. The key to wine aroma and taste is flavor substances like free amino acids (FAAs), volatile fatty acids, higher alcohols, and esters. Amino acid (AA) metabolisms in yeast are an important source of these secondary compounds, which vary with the fermentation conditions. This study explored and optimized the impact of different parameters (carbon source, inoculum, pH, temperature) on FAA contents and dynamics in greengage wine. The results demonstrated that total and essential amino acid (EAA) content rose with a higher proportion of glucose, less yeast inoculation, higher temperature, and higher initial pH. With the results obtained it was concluded that the condition of 22.4°C, pH 4.5, and 3% inoculation was optimum for a 14.9-fold increase of EAAs in fermented greengage wine. In the long run, the research will aid in the development of the greengage brewing industry.