ABSTRACT This study systematically investigated the extraction and identification of umami peptides, as well as their mechanism for masking bitterness. The hydrolysate of Antarctic krill was isolated and purified, and umami components were identified through sensory evaluation and instrumental analysis. 12 potential umami peptides were obtained via virtual screening using databases. ERDWPEGRG, EHFETATRD, and DWPEGR were selected for functional validation based on molecular docking binding energy screening. The results showed that the three umami peptides had bitter taste inhibition efficiencies of 81.14%, 92.16%, and 93.02%. Molecular docking analysis revealed that the binding sites of the three umami peptides (Phe 76, Trp 89, Val 180) overlap with those of quinine sulfate, indicating that they exert their masking effect through competitive binding to the bitter taste receptor. This research will provide a theoretical basis for developing natural, safe bitterness‐masking agents and advance the process of high‐value utilization of Antarctic krill.
ABSTRACT To investigate the regulatory effects of α‐lipoic acid (α‐LA) treatment on the senescence process of postharvest strawberry fruit, strawberries were immersed in 0.5 g/L α‐LA solution. By analyzing the contents of total soluble solids (TSS), titratable acidity (TA), predominant soluble sugars, and primary organic acids, as well as the activities and transcript levels of related key metabolic enzymes, the preliminary regulatory trends of α‐LA treatment on sugar and organic acid accumulation were investigated. The results showed that α‐LA treatment maintained higher levels of TSS and TA. Meanwhile, by regulating the activities of sucrose phosphate synthase (SPS), sucrose synthase (SS), acid invertase (AI), and neutral invertase (NI), along with the expression of related genes, α‐LA treatment maintained a higher net sucrose pool, while attenuating the sharp accumulation of glucose and fructose during late storage. Furthermore, α‐LA treatment inhibited the degradation of organic acids by regulating the activities of citrate synthase (CS), aconitase (ACO), malate dehydrogenase (MDH), and NADP‐malic enzyme (NADP‐ME), as well as their related gene expression levels. In conclusion, α‐LA treatment maintained the sweetness‐acidity profile of strawberry fruit during storage and delayed senescence, providing preliminary biochemical and transcriptional insights into α‐LA‐regulated sugar and organic acid dynamics.
ABSTRACT Rhinacanthus nasutus (L.) Kurz is a medicinal plant whose roots, stems, and leaves are commonly used in tea and traditional Chinese medicine; however, the beneficial effects of its flowers remain to be investigated. In this study, the lactic acid bacteria (LAB) found in the flowers of R. nasutus (L.) Kurz were isolated using a medium containing fructose, which is abundant in the flowers, and their microbial characteristics were subsequently analyzed. The isolated LAB strain was identified as Weissella cibaria based on whole‐genome sequencing and was designated as HRL3. This strain was a facultative anaerobe whose growth was promoted under aerobic conditions, and it was classified as a heterofermentative LAB that produced lactate and ethanol via lactate fermentation. In addition, the HRL3 strain exhibited a unique carbohydrate utilization profile that differed from the type strain of W. cibaria . The immunostimulatory effects of the HRL3 strain were also investigated in this study. When added to mouse spleen cells, the HRL3 strain induced the production of IFN‐α, which is a cytokine that plays a key role in enhancing antiviral immune responses. This induction could occur through recognition by endosomal Toll‐like receptor (TLR) 3 and TLR9. Dectin‐1 may also contribute to IFN‐α production induced by the HRL3 strain. In an influenza A virus (IAV)‐infected mouse model, oral administration of the HRL3 strain was associated with increased IFN‐α mRNA expression, reduced IAV M mRNA expression, and attenuation of pulmonary histopathological changes. These findings provide new insights into the functional potential of R. nasutus (L.) Kurz flowers and the immunomodulatory activity of the HRL3 strain.
ABSTRACT This study investigated the influence of amylose content on the structural and physicochemical properties of starch‐whey protein isolate (WPI) ‐lauric acid (LA) ternary complexes. Three wheat starches (NWS: 39.82% amylose, HWS1: 78.57% amylose, HWS2: 81.62% amylose) were used to investigate the morphology, short‐range ordering degree (OD), X‐ray diffraction (XRD), thermal properties, and starch digestibility of their complexes with WPI and LA. NWS showed A‐type crystallinity, whereas HWS1 and HWS2 exhibited B‐type crystallinity with lower relative crystallinity. The structural and functional properties of ternary complex showed systematic changes compared to their corresponding binary complexes and gelatinized starches. Specifically, higher amylose content reduced short‐range ordering degree (OD) and relative crystallinity of native starches while concurrently enhancing thermal stability, enthalpy change (ΔH), and resistance to enzymatic digestion. Morphological analysis revealed distinct particle restructuring, with FT‐IR spectroscopy identifying that increasing amylose content led to greater formation of starch‐WPI‐LA complexes. Notably, these starch‐WPI‐LA ternary complexes exhibited higher OD compared to starch‐LA binary complexes. These findings provide critical criteria for starch selection in functional food formulations.
ABSTRACT Curcumin, a natural food colorant and functional ingredient, suffers from poor stability, low lipophilicity, and limited oral bioavailability. This study, for the first time, employs a whole‐cell catalyst (Rhizopus arrhizus MQ1 isolated from lipid‐rich soil) to achieve green acylation of curcumin in a non‐aqueous system, aiming at efficient synthesis of curcumin monoacetate (CA). Using vinyl acetate as the acyl donor, the reaction conditions were optimized (DMSO, 40 mg/mL whole‐cell catalyst, substrate ratio 1:62.5, 60°C), reaching a conversion >90%. To investigate the substrate specificity of the whole‑cell catalyst towards acyl donors of different chain lengths, vinyl butyrate and vinyl octanoate were also tested, yielding the corresponding monoacylated derivatives—curcumin monobutyrate (CB) and curcumin monooctanoate (CO). All three derivatives showed increased Log P relative to curcumin; CA (3.32) fell within the optimal range and exhibited the highest aqueous solubility (Log S = ‐4.11) among the series. All three derivatives exhibited improved photothermal stability, stability in simulated body fluids, and tyrosinase inhibitory activity compared to curcumin. Among them, CA showed superior overall performance: >75% retention after 6 h at 100°C and an IC 50 of 125.94 µmol/L (23.8% higher potency than curcumin), making it a promising candidate for functional food ingredients, anti‑browning agents, and natural colorant improvement. This study provides a green whole‐cell acylation strategy that not only achieves high conversion of CA but also demonstrates substrate specificity towards acyl donors of different chain lengths.
