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Shaken Hunan black tea is an innovative Hunan black tea processed by adding shaking to the traditional Hunan black tea. The quality of shaken black tea is influenced by leaf grades of different maturity. In this study, the taste and aroma quality of shaken Hunan black tea processed with different grades were analyzed by sensory evaluation (SP, HPLC, and HS-SPME/GC-MS). The results showed that shaken Hunan black tea processed with one bud and two leaves has the best quality, which has a sweet, mellow, and slightly floral taste, as well as a floral, honey, and sweet aroma. Moreover, caffeine and EGCG were identified as the most important bitter and astringent substances in shaken Hunan black. Combined with the analysis of GC-MS and OAV analysis, geraniol, jasmone, β-myrcene, citral, and trans-β-ocimene might be the most important components that affect the sweet aroma, while methyl jasmonate, indole, and nerolidol were the key components that affect the floral aroma of shaken Hunan black tea. This study lays a foundation for this study of the taste and aroma characteristics of shaken Hunan black tea and guides enterprises to improve shaken black tea processing technology. [ABSTRACT FROM AUTHOR]

The standard tea samples are indispensable for the objective and accurate identification of tea quality. In this study, the preparation process of standard Hunan black tea standard samples was introduced and its quality was analyzed. The results of the sensory evaluation and biochemical components show that the supper grade of standard Hunan black tea sample had the highest amino acid content, making the taste sweet and mellow. The terpenoid contents in 110 volatile aroma substances identified were significantly higher than those of other tea samples, and the aroma was tender, sweet, rich and lasting. The first grade standard sample had the highest water extracts and catechin content, making the taste mellow. Meanwhile 114 volatile aroma substances were identified, with the contents of various volatile components in the middle level, showing a pure sweet flavor. The second grade standard sample contained relatively low taste component contents, showing sweet with a bit thick taste, and 109 volatile aroma substances were identified. The contents of fatty acid-derived volatile substances and carotenoids were significantly higher than those of other tea samples, showing sweet and floral aroma. This study can provide a reference for the processing and production of Hunan black tea. [ABSTRACT FROM AUTHOR]

The study of protein subcellular localization, dynamics, and regulation in live cells has been profoundly transformed by the advent of techniques that allow the tagging of endogenous genes to produce fluorescent fusion proteins. These methods enable researchers to visualize protein behavior in real time, providing valuable insights into their functions and interactions within the cellular environment. Many current gene tagging studies employ a two-step process where visible markers, such as eye color changes, are used to identify genetically modified organisms in the first step, and the visible marker is excised in the second step. Here, we present a one-step protocol to perform precise and rapid endogenous gene tagging in Drosophila melanogaster, which enables screening for engineered lines without the visible eye marker, offering a significant advantage over past methods. To screen for successful gene-tagging events, we employ a PCR-based technique to genotype individual flies by analyzing a small segment from their middle leg. Flies that pass the screening criteria are then used to produce stable stocks. Here, we detail the design and construction of CRISPR editing plasmids and methods for screening and confirmation of engineered lines. Together, this protocol improves the efficiency of endogenous gene tagging in Drosophila significantly and enables studies of cellular processes in vivo.