Quality Differences of Zhenghe White Tea from Different Altitudes

To explore the effect of growing altitude on the quality of Zhenghe white tea, the sensory quality and biochemical composition of tea leaves and Zhenghe white tea from different altitudes were evaluated, and multivariate statistical analysis was applied to the obtained data. The results of sensory evaluation showed that there were significant differences in the quality of white tea from different altitudes. The mid- and high-altitude white tea tasted fresh, mellow and clean with a clean and pure aroma, while the low-altitude white tea tasted mellow and thick with a floral aroma. Partial least squares discriminant analysis (PLS-DA) showed that soluble sugars, caffeine, 3-carene, verbenenol, terpene oleene, cis-2-pentenol, 2-ethylfuran and cis-2-hexene-1-alcohol were the key components to distinguish fresh tea leaves from different altitudes. The contents of soluble sugar, cis-2-hexene-1 alcohol and cis-2-pentenol were higher in the mid- and high-altitude samples, while the contents of volatile components such as caffeine, 3-carene, verbenol and terpinolene were higher in the low-altitude samples. Soluble sugar, free amino acid, terpinolene, verbenol, 2-ethyl furan, 2-methylbutyraldehyde, 2-phenylethanol and 3-carene were the key components to distinguish white tea from different altitudes. The contents of soluble sugar and free amino acid were higher in the high-altitude white tea, and the contents of volatile components such as terpinolene, verbenol, phenyl ethanol and 3-carene were higher in the mid- and low-altitude samples, but low in the high-altitude samples. According to odor activity value (OAV) analysis, 2-methyl butyl aldehyde, 3-carene and terpinolene could be used as the characteristic volatile components to identify white tea samples from different altitudes. The results of this study will provide a reference for further exploring the flavor quality of tea from different altitudes

The crystal structure of 4-aminiumbiphenyl, C18H17NO3S

C18H17NO3S, monoclinic, Cc (no. 9), a = 32.036(3) Å, b = 7.2154(7) Å, c = 7.4283(8) Å, β = 99.943(2)∘, V = 1691.3(3) Å3, Z = 4, Rgt(F) = 0.0343, wRref(F2) = 0.0821, T = 298 K

Differences in Flavor Quality between White Peony Tea with Different Storage Times

To explore the effect of storage time on the flavor and quality of white peony tea, sensory evaluation and volatile and non-volatile composition analysis of 12 white peony tea samples made from three different varieties: Fudingdahao (FDDH), Zhenghedabai (ZHDB) and Fujiangshuixian (FJSX) were carried out, and the resulting data were analyzed by multivariate statistical analysis combined with multivariate statistical analysis. The results showed that during the storage process, the content of tea polyphenols and free amino acids decreased, and the ratio of polyphenols to amino and the contents of soluble sugar, flavonoids and thearubigin increased, so that the taste of white peony tea was sweet, mellow, sweet after taste and stale. The large decrease in the content of alcohol substances resulted in a reduction in the refreshing and floral aroma of white peony tea. Totally 12 differential volatiles were key to changing the aroma types of white peony tea. α-Farnesene, linalool oxide II, methyl salicylate, linalool, cis-2-pentene-1-alcohol and hexanal were the key components responsible for the floral, pekoe-like and refreshing aroma. cis-Linalool oxide and neryl oxide were also positively related to the formation of the floral aroma, and the latter was also key to the formation of the pekoe-like aroma. cis-3-Hexen-1-ol and phenethyl alcohol were also positively correlated with the formation of the refreshing aroma. In addition, 4-isopropyltoluene was the key component responsible for the honey-like and herbal aroma. Linalool oxide II and neryl oxide were the key components responsible for the jujube-like aroma. cis-Linalool oxide was the key component responsible for the plum-like aroma. The 4-isopropyltoluene and isobutyraldehyde were the key components contributing to the woody aroma. This study provides scientific insights into the formation of the differences in the flavor and quality of white peony tea of different ages, which could provide a reference for the improvement of tea flavor

RNA Methylome Reveals the m6A-mediated Regulation of Flavor Metabolites in Tea Leaves under Solar-withering

The epitranscriptomic mark N6-methyladenosine (m6A), which is the predominant internal modification in RNA, is important for plant responses to diverse stresses. Multiple environmental stresses caused by the tea-withering process can greatly influence the accumulation of specialized metabolites and the formation of tea flavor. However, the effects of the m6A-mediated regulatory mechanism on flavor-related metabolic pathways in tea leaves remain relatively uncharacterized. We performed an integrated RNA methylome and transcriptome analysis to explore the m6A-mediated regulatory mechanism and its effects on flavonoid and terpenoid metabolism in tea (Camellia sinensis) leaves under solar-withering conditions. Dynamic changes in global m6A level in tea leaves were mainly controlled by two m6A erasers (CsALKBH4A and CsALKBH4B) during solar-withering treatments. Differentially methylated peak-associated genes following solar-withering treatments with different shading rates were assigned to terpenoid biosynthesis and spliceosome pathways. Further analyses indicated that CsALKBH4-driven RNA demethylation can directly affect the accumulation of volatile terpenoids by mediating the stability and abundance of terpenoid biosynthesis-related transcripts and also indirectly influence the flavonoid, catechin, and theaflavin contents by triggering alternative splicing-mediated regulation. Our findings revealed a novel layer of epitranscriptomic gene regulation in tea flavor-related metabolic pathways and established a link between the m6A-mediated regulatory mechanism and the formation of tea flavor under solar-withering conditions

Insights into nano-mechanical degradation behavior of Ag/Ti2AlC composite under different arc erosion stages

Serious arc erosion is the main reason for premature failure of the Ag-matrix composite electrical contact materials in actual service. Clarifying the structure and property degradation process is crucial for creating eco-friendly Ag/MAX electrical contacts and upgrading high-performance materials for low-voltage switch applications. In this study, the representative Ag/Ti2AlC electrical contacts were designed into three arc erosion stages (from 1 to 5610 cycles) by ex-situ arc discharging experiment, and the nanoindentation technique was then applied to in-depth analyze the evolution behavior of nano-mechanical properties by comparing nano hardness, modulus, creep, continuous stiffness, elastic/plastic deformation, and NanoBlitz 3D Mapping indentation results in different erosion stages. Finally, the inherent relationship among the structural dissociation of Ti2AlC, and compositional changes of Ag/Ti2AlC interface and nano-mechanical properties of composite was revealed, and the material degradation model and anti-arc erosion mechanism were proposed. This work further elucidates the intrinsic source of excellent arc erosion resistance and degradation process of Ag/Ti2AlC composite from the nano-mechanical perspective and lays a theoretical foundation for the future design and optimization of this material system