Background: White leaf No.1 is a typical albino tea cultivar grown in China and it has received increased attention in recent years due to the fact that white leaves containing a high level of amino acids, which are very important components affecting the quality of tea drink. According to the color of its leaves, the development of this tea cultivar is divided into three stages: the pre-albinistic stage, the albinistic stage and the regreening stage. To understand the intricate mechanism of periodic albinism, a comparative proteomic approach based on two-dimensional electrophoresis (2-DE) and mass spectrometry was adopted first time to identify proteins that changed in abundance during the three developmental periods. Results: The 2-DE results showed that the expression level of 61 protein spots varied markedly during the three developmental stages. To analyze the functions of the significantly differentially expressed protein spots, 30 spots were excised from gels and analyzed by matrix-assisted laser desorption ionization-time of flight-tandem mass spectrometry. Of these, 26 spots were successfully identified. All identified protein spots were involved in metabolism of carbon, nitrogen and sulfur, photosynthesis, protein processing, stress defense and RNA processing, indicating these physiological processes may play crucial roles in the periodic albinism. Quantitative real-time RT-PCR analysis was used to assess the transcriptional level of differentially expressed proteins. In addition, the ultrastructural studies revealed that the etioplast-chloroplast transition in the leaf cell of White leaf No. 1 was inhibited and the grana in the chloroplast was destroyed at the albinistic stage. Conclusions: In this work, the proteomic analysis revealed that some proteins may have important roles in the molecular events involved in periodic albinism of White leaf No. 1 and identificated many attractive candidates for further investigation. In addition, the ultrastructural studies revealed that the change in leaf color of White leaf No. 1 might be a consequence of suppression of the etioplast-chloroplast transition and damage to grana in the chloroplast induced by temperature. These results provide much useful information to improve our understanding of the mechanism of albinism in the albino tea cultivar.

• Aroma characteristics of Fu brick tea were classified into three types. • Key aroma compounds in three aroma types of Fu brick tea were identified. • Relationship between aroma compounds and aroma attributes was illuminated.

While extensive research has focused on the flavor of Fu brick tea (FBT), the perceptual interactions among its aromatic components remain unclear. To address this, twenty representative aroma compounds were selected from FBT to determine their thresholds and evaluate their interactions by analyzing threshold changes before and after mixing. The results revealed discrepancies between the determined thresholds and literature values, particularly for α-terpineol, methyl heptenone, and geranylacetone, which demonstrated ratios of 73.54, 6.62, and 6.41, respectively. Mixtures with similar aromas or structures exhibited synergy, whereas those with differing aromas or structures displayed masking effects. Additionally, the odor compound (E)-nerolidol was added to the tea infusion at a concentration below its threshold level to investigate its impact on the overall aroma perception of FBT through sensory analysis and electronic nose assessments. The findings indicated that sub-threshold compounds could significantly influence the overall aroma profile of FBT.

Background: (−)-Epigallocatechin-3-gallate (EGCG), the most abundant catechin found in green tea, effectively reduces body weight and tissue and blood lipid accumulation. To explore the mechanism by which EGCG inhibits cellular lipid accumulation in free fatty acid (FFA) induced HepG2 cell culture, we investigated the proteome change of FFA-induced HepG2 cells exposed to EGCG using two-dimensional gel electrophoresis and mass spectrometry. Results: In this study, 36 protein spots showed a significant change in intensity by more than 1.5-fold from the control group to the FFA group and from the FFA group to the FFA + EGCG group. Among them, 24 spots were excised from gels and identified by LC-MS/MS. In total, 18 proteins were successfully identified. All identified proteins were involved in lipid metabolism, glycometabolism, antioxidant defense, respiration, cytoskeleton organization, signal transduction, DNA repair, mRNA processing, iron storage, or were chaperone proteins. This indicated that these physiological processes may play roles in the mechanism of inhibition of lipid accumulation by EGCG in FFA-induced HepG2 cells. Western blotting analysis was used to verify the expression levels of differentially expressed proteins, which agree with the proteomic results. Conclusions: From the proteomic analysis, we hypothesized that EGCG reduced cellular lipid accumulation in FFA-induced HepG2 cells through the activation of AMP-activated protein kinase (AMPK) resulting from the generation of reactive oxygen species (ROS). The induction of ROS may be a result of EGCG regulation of the antioxidant defense system. Activation of AMPK shifted some FFA toward oxidation, away from lipid and triglyceride storage, and suppressed hepatic gluconeogenesis. The findings of this study improve our understanding of the molecular mechanisms of inhibition of lipid accumulation by EGCG in HepG2 cells.