Foods

Plant cell culture represents a sustainable platform for the production of high-value natural products. Although ultraviolet A (UV-A) radiation is established as an inducer of phenylpropanoid metabolism, its precise regulatory role in downstream flavonoid biosynthesis within grape cells remains unclear. Using red and white-type callus derived from Vitis vinifera L. cv. Cabernet Sauvignon berry skins, we investigated the effects of UV-A treatments with two durations (45 min and 90 min) on flavonoid biosynthesis. Metabolite profiling demonstrated that UV-A predominantly promoted proanthocyanidin accumulation in white-type callus, while stimulating the global flavonoid pathway in a dose-dependent manner in red callus. Transcriptional analysis identified structural genes potentially governing flavonoid product channeling in both callus types under UV-A exposure. Weighted Gene Co-expression Network Analysis (WGCNA) constructed light-responsive regulatory modules, uncovering potential mechanisms coordinating flavonoid pathway gene expression in response to UV-A. These findings demonstrate how the interaction of callus-type and UV-A shapes flavonoid metabolic flux, providing insights into the regulation of plant cell culture metabolites.

In this study, purified Liquidambar formosana Hance melanin (P-LHM) was structurally characterized and evaluated for stability. The yield of P-LHM was approximately 3.47%. Analytical results revealed P-LHM is a melanin-rich complex where eumelanin and pheomelanin polymers are intimately associated with specific flavonoids, phenolic acids, and terpenoids. The condensation molecular formula of P-LHM might be ([C₂₄H₂₉NO₉]_n). The stability evaluation showed that under specific conditions (natural light, darkness, pH = 7–11, 25–100 °C, Na⁺, Al³⁺, Fe²⁺ solution, and low concentrations of reducing agents), the retention rate of P-LHM was >90%. Given its excellent stability, LHM may be used as a new type of food ingredient in the processing of black-colored foods. Meanwhile, the rich phenolic compounds provide a theoretical basis for the development of functional colorants, enhancing the functional value of food colorants.

This study investigated the effects of adding Lactobacillus helveticus H11 on the fermentation characteristics, storage performance, and probiotic functionality of brown fermented milk. The results were obtained by analyzing the microrheological properties during the fermentation process, as well as changes in titratable acidity, viable cell count, texture, ACE (angiotensin-converting enzyme) inhibition rate, and metabolite profiles during storage. The findings indicated that the addition of H11 significantly shortened the fermentation time of brown fermented milk and improved its gel structure. Simultaneously, it delayed the post-acidification phenomenon during storage, enhancing storage stability. Moreover, it enhanced the ACE inhibitory activity of the product, demonstrating potential antihypertensive health benefits. Metabolomic analysis further revealed that H11 promoted the production of flavor compounds, such as phenylacetaldehyde and phenyllactic acid, enriching the flavor diversity. Additionally, it concurrently regulated the metabolism of tyrosine and vitamin B6. These discoveries provide a scientific basis for the commercial development of brown probiotic products.