Drying methods play a crucial role in the formation of green tea aromas. This study investigated the aroma characteristics and volatile component profiles of large-leaf green tea under hot-air drying, pan-fired drying, and sun drying. The results revealed significant differences in the sensory aroma characteristics and volatile components of the large-leaf green tea among the three drying methods. The pan-fire-dried green tea (PDGT) exhibited a distinct roasted aroma, while the hot-air-dried green tea (HDGT) and sun-dried green tea (SDGT) displayed a faint scent and lasting aroma characteristics, with the SDGT additionally featuring a noticeable sun-dried odor. A total of 48 differential volatile components were identified, among which β-Ionone, (E)-β-Ionone, 2,2,6-Trimethylcyclohexanone, Dihydroactinidiolide, BenzeneacetAldehyde, 2-Pentylfuran, 1,1,6-Trimethyl-1,2-dihydronaphthalene, δ-Cadinene, β-Myrcene, Geranylacetone, o-Cymene, 6-Methyl-5-hepten-2-one, (E)-β-Ocimene, and BenzAldehyde were identified as the primary contributors to the aroma differences among the three large-leaf green teas. Additionally, 43 differential volatile compounds were found to be significantly correlated with at least one of the aroma types (floral, sweet, green, faint scent, nutty, or roasted). The findings of this study provide a theoretical foundation for understanding the formation of aroma qualities in large-leaf green tea and offer valuable insights for improving its aromatic characteristics.

Anadequate selenium (Se) intake can enhance human immunity and prevent diseases development. About one billion people in the world have varying degrees of Se deficiency in the world. Organic Se from tea infusion is the most easily absorbed and utilized Se form by the human body. Therefore the production of tea plants rich in Se is an effective way to increase Se dietary intake, but there are few studies on the involvement and functions of miRNAs in the responses of tea plants after Se treatment. MicroRNAs (miRNAs) are endogenous (non-coding) single-stranded RNAs that play crucial roles in regulating plant nutrient element acquisition and accumulation. Physiological analysis discovered that the total Se content in tea plant roots markedly increased under 0.05 mmol·L⁻¹ selenite treatment, with no toxicity symptoms in the leaves and roots. To screen the miRNAs responsive to Se treatment in tea plants, miRNA libraries were constructed from the tea cultivar “Echa 1”. Using high-throughput sequencing, 455 known miRNAs and 203 novel miRNAs were identified in this study. In total, 13 miRNAs were selected that were differentially expressed in tea plants’ roots under 0.05 mmol·L⁻¹ selenite treatments. Gene Ontology enrichment analysis revealed that the target genes of the differentially expressed miRNAs mainly belonged to the metabolic process, membrane, and catalytic activity ontologies. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis suggested that beta-alanine, taurine, hypotaurine, and sulfur metabolism were the most enriched pathways among the differentially expressed miRNAs, implying their involvement in Se accumulation and tolerance in tea plants. Further characterization of the data revealed that the number of novel miRNAs was comparable to that of known miRNAs, indicating that novel miRNAs significantly contributed to the regulation of Se accumulation in tea plant roots. Thisstudy lays the foundation for further research on the regulatory mechanisms underlying Se accumulation and tolerance in tea plants, providing targets to molecular breeding strategies for improving tea nutritional properties.

Kujingcha (KJC) is a widely consumed substitute tea due to its unique flavor quality and health benefits. However, the biochemical basis for the formation of KJC’s unique flavor quality and health benefits remain unclear. In this study, using Camellia sinensis green tea and its processed fresh leaves as a control, we systematically analyzed the non-volatile and volatile components in KJC and its processed fresh leaves. The results indicate that high levels of flavonoids and water-soluble sugars, and low levels of amino acids and water-soluble proteins, are important biochemical foundations for the formation of taste quality in KJC. High aldehyde, alkene and heterocyclics contents contribute significantly to the aroma of KJC, among which heterocyclics are the key components for the formation of KJC’s rich pan-fried bean-like aroma. Flavonoids such as neohesperidin, hyperoside, rutin, astilbin and morin are important components for the formation of KJC’s health benefits.

Drying plays a critical role in shaping tea quality. This study systematically investigated the differences in the taste/mouthfeel quality of hot-air drying raw Pu-erh tea (HDRPT), pan-fired drying raw Pu-erh tea (PDRPT), and sun drying raw Pu-erh tea (SDRPT). The results showed that SDRPT exhibited a mellow and thick mouthfeel with a sweet aftertaste, and significantly higher intensities of umami and sweetness compared to PDRPT and HDRPT. The relatively higher contents of amino acids such as theanine, glutamic acid, aspartic acid, and glutamine, along with water-soluble sugars, and relatively lower contents of catechins, including ECG and EGCG, were identified as key material bases contributing to the unique taste/mouthfeel quality of SDRPT. A total of 1987 non-volatile components were detected, from which 137 differential non-volatile components were screened. Among these, 75 components in SDRPT showed significant differences from both PDRPT and HDRPT, with the majority exhibiting higher relative contents in SDRRT, particularly notable among lipids, phenolic acids, and terpenoids. Furthermore, all 75 differential components were significantly correlated with at least one taste/mouthfeel attribute, with most showing significant positive correlations with umami, sweetness, and sourness, and significant negative correlations with bitterness and astringency. These findings provide a theoretical foundation for understanding the mechanism by which drying techniques influence the taste/mouthfeel quality formation of raw Pu-erh tea, and offer a scientific basis for improving its quality.