Binbin Li

Background: The sensory quality of melon (Cucumis melo L.) is determined by the complex interplay of metabolites within the fruit. However, the underlying metabolic mechanisms based on consumer sensory experience remain underexplored. Methods: Sensory evaluation was conducted on twelve melon cultivars, recording flesh color and quantitatively scoring acidity, sweetness, firmness, and aroma intensity. Based on the sensory results, eight cultivars were selected to establish two contrasting groups: sweet-type vs. acidic-type and orange-fleshed vs. green-fleshed. Untargeted metabolomics (UPLC-QTOF-MS) was then performed to analyze the samples, and differential metabolites were screened using OPLS-DA combined with univariate analysis. Results: Pathway enrichment analysis revealed that the key distinction between sweet and acidic taste profiles was associated with the specific accumulation of citric acid within the tricarboxylic acid (TCA) cycle in the acidic-type group. Regarding flesh color, the orange-fleshed group was enriched with carotenoid derivatives like β-citraurinene and the oxidized tocopherol product α-tocopherolquinone, whereas the green-fleshed group mainly accumulated phytol, a chlorophyll degradation product, along with more abundant terpenoids. Conclusions: By integrating sensory phenotyping with metabolomic analysis, this study identified key differential metabolites and candidate pathways associated with taste and color in melon, providing metabolic insights and data resources for quality evaluation and regulation.

Jujube (Ziziphus jujuba Mill.) is a functional food with both edible and medicinal properties. It is rich in various bioactive compounds and holds significant development value and application prospects in food nutrition, medicine, and health. This review systematically summarizes the research progress on the synthesis mechanism and pharmacological activities of phenolic compounds in jujube fruits, clarifies the composition of their main components, sorts out the research advances in extraction technologies of jujube phenolic compounds, and focuses on analyzing the content differences and distribution patterns across cultivars and tissue parts. On this basis, it examines the regulatory mechanisms of phenolic compound synthesis in depth, with a particular focus on elucidating the regulatory networks of genes and transcription factors involved in flavonoid biosynthesis. Meanwhile, this review comprehensively summarizes the pharmacological activities of phenolic compounds in jujube fruits, including antioxidant, anticancer, antibacterial, anti-inflammatory, and hypoglycemic effects. It also elucidates the molecular mechanisms underlying these bioactivities, such as regulating signaling pathways and scavenging free radicals. Finally, it analyzes the limitations of current research and proposes key directions for future development. This review provides theoretical support and a scientific basis for the in-depth development and utilization of jujube phenolic compounds as well as for the research and development of related functional foods and drugs.