The storage period of tea is a major factor affecting tea quality. However, the effect of storage years on the non-volatile major functional components and quality of green tea remains largely unknown. In this study, a comparative analysis of organic green teas with varying storage years (1–16 years) was conducted by quantifying 47 functional components, using electronic tongue and chromatic aberration technology, alongside an evaluation of antioxidative capacity. The results indicated a significant negative correlation between the storage years and levels of tea polyphenols, total amino acids, soluble sugars, two phenolic acids, four flavonols, three tea pigments, umami amino acids, and sweet amino acids. The multivariate statistical analysis revealed that 10 functional components were identified as effective in distinguishing organic green teas with different storage years. Electronic tongue technology categorized organic green teas with different storage years into three classes. The backpropagation neural network (BPNN) analysis demonstrated that the classification predictive ability of the model based on the electronic tongue was superior to the one based on color difference values and 10 functional components. The combined analysis of antioxidative activity and functional components suggested that organic green teas with shorter storage periods exhibited stronger abilities to suppress superoxide anion radicals and hydroxyl radicals and reduce iron ions due to the higher content of eight components. Long-term-stored organic green teas, with a higher content of substances like L-serine and theabrownins, demonstrated stronger antioxidative capabilities in clearing both lipid-soluble and water-soluble free radicals. Therefore, this study provided a theoretical basis for the quality assessment of green tea and prediction of green tea storage periods.

To explore the effects of harvest seasons and etiolated cultivars on the volatile compounds of steamed green teas, this study analyzed comprehensively the volatile compounds of steamed green teas using simultaneous distillation extraction-gas chromatography–mass spectrometry (SDE-GC–MS) and chemometrics analytical techniques in combination with odor activity value (OAV). Additionally, the in vitro antioxidant capacity of the steamed green teas was evaluated. The results showed that 95 volatile compounds were identified, among which aldehydes, ketones, alcohols, and acids were the main types in steamed green teas made from etiolated tea cultivars. Furthermore, the relative content of volatile compounds in steamed green tea was significantly negatively correlated with season (P < 0.05). In steamed green teas harvested in different seasons, spring tea contained a higher abundance of volatile compounds such as (+)-δ-cadinene, farnesyl acetone, carvenone, trans-β-ionone, and nerolidol. The differences of total volatile compounds among the three etiolated tea cultivars were not remarkable (P > 0.05). Combined with the OAV, 20 and 19 key aroma compounds in steamed green teas from different harvest seasons and cultivars were identified, respectively, which could bring unique aromas to different steamed green tea samples. By comparison, summer tea had the strongest antioxidant capacity, while there was no obvious difference in the antioxidant capacity among cultivars. This study provided a scientific basis for the aroma quality of steamed green teas made from etiolated tea cultivars in different harvest seasons.

A highly specific and high extraction-rate method for the analysis of dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), diisobutyl phthalate (DiBP), and di-(2-ethyl) hexyl phthalate (DEHP) in tea samples was developed. Based on three-factor Box–Behnken response surface design, solid-phase extraction (SPE) of five phthalate ester (PAE) residues in tea was optimized. Optimal extraction conditions were found for extraction temperature (40 °C), extraction time (12 h), and ratio of tea to n-hexane (1:20). The dynamic distribution of PAEs at each stage of black tea processing was also analyzed, and it was found that the baking process was the main stage of PAE emission, indicating that traditional processing of black tea significantly degrades PAEs. Further, principal component analysis of the physicochemical properties and processing factors of the five PAEs identified the main processing stages affecting the release of PAEs, and it was found that the degradation of PAEs during black tea processing is also related to its own physicochemical properties, especially the octanol–water partition coefficient. These results can provide important references for the detection, determination of processing losses, and control of maximum residue limits (MRLs) of PAEs to ensure the quality and safety of black tea.

The Hangzhou White Chrysanthemum (Chrysanthemum morifolium Ramat) is one of the “Zhejiang eight flavors” in traditional Chinese medicine. The phosphatidylethanolamine-binding protein (PEBP) plays an important role in flowering and floral organ development. Even so, the biological role of PEBPs in the Hangzhou White Chrysanthemum has not been studied, which attracted us. Here, nine CmPEBP genes that contain the PF01161 domain were identified in the Hangzhou White Chrysanthemum for the first time, and their biological role in flowering was preliminarily studied. A phylogenetic analysis classified the CmPEBP genes into three subfamilies: MFT-like, TFL-like, and FT-like genes. The differential expression analysis was performed under different tissues and different stressors using qRT-PCR. It showed that each CmPEBP displayed tissue-specific expression patterns. Expression patterns in response to different temperatures and hormone stressors were investigated. They were finally demonstrated to be differentially expressed. TFL-like gene expression, which delayed reproductive growth, was upregulated under heat stress. Conversely, FT-like gene expression was upregulated under low temperatures. CmFT1 expression could be inhibited by GA (gibberellin), 6-BA (benzylaminopurine), ET (ethylene), and MeSA (methyl salicylate) but could be activated by IAA (indole-3-aceticacid), ABA (abscisic acid), and SA (salicylic acid) in the dark, whereas CmFT2 and CmFT3 expression levels were upregulated by ET, MeJA (methyl jasmonate), and ABA but were downregulated by 6-BA, SA, and MeSA. GA, IAA, SA, and MeSA inhibited CmTFL gene expression under light and dark treatments. Further research on CmPEBP genes in the Hangzhou White Chrysanthemum could better determine their roles in flowering and floral organ development, especially in response to the prolonged spraying of exogenous hormones.

Plasticizers, i.e., phthalate esters (PAEs) were liable to be detected from fresh tea leaves and tea products. In order to monitor the pollution of PAEs in tea plants and compare the difference among PAEs content of tea cultivars, fifteen elite cultivars in tea plant cultivar gardens were chosen. PAEs were extracted from the upper mature leaves and lower mature leaves of tea bushes and determined via GC–MS once every two months, six times in total in one anniversary. DMP, DEP, DiBP, DBP, and DEHP were detected in fifteen tea cultivars. DBP was the predominant congener in fifteen tea cultivars, which was followed by DiBP. PAEs content in upper mature leaves was significantly lower than that in lower mature leaves in all months. There was no significant difference among PAEs content from the fifteen tea cultivars. Except for summer, the PAEs content of fresh tea leaves gradually increased from spring to winter. The correlation analysis result was that PAEs had significant negative correlation with air temperature and positive correlation with air quality index (p < 0.01). The mutual correlation among the five PAEs were significant (p < 0.05). According to cluster analysis, three types of fresh tea leaves with high, medium, and low accumulation accounted for 26.7%, 20%, and 53.3%, respectively. The results could supply a reference for monitoring of pollution of PAEs in fresh tea leaves, as well as an evaluation of PAEs content difference of tea plant cultivars.