This study investigated the effects of enzymolysis combined with carboxymethylation or acetylation modification on the chemical composition, structure, physicochemical properties, and hypoglycemic activity of oil palm kernel expeller dietary fiber. The results demonstrated that both composite modification methods rendered the microstructure of oil palm kernel expeller dietary fiber more loose and porous. Fourier transform infrared (FT-IR) spectroscopy confirmed the successful introduction of carboxymethyl and acetyl groups via chemical modification, and the stretching vibration of the absorption peak around 3400 cm⁻¹ indicated that the composite modifications disrupted the hydrogen bonds in the fiber. After enzymolysis combined with carboxymethylation and enzymolysis combined with acetylation, the soluble dietary fiber content of oil palm kernel expeller fiber increased significantly from 4.00% to 16.14% and 12.85% (P<0.05); water-holding capacity rose from 2.06 g/g to 5.72 g/g and 4.15 g/g; water-swelling capacity increased from 1.01 mL/g to 3.58 mL/g and 2.46 mL/g; viscosity increased from 4.08 cP to 13.90 cP and 7.71 cP; glucose adsorption capacity enhanced from 1.84 μmol/g to 3.99 μmol/g and 4.53 μmol/g; and glucose diffusion inhibition capacity improved from 16.32% to 38.18% and 25.15%, respectively. In addition, for the oil palm kernel expeller dietary fiber treated with enzymolysis combined with carboxymethylation, its α-amylase inhibitory activity (19.41%) was increased by 0.43 times compared with that of the unmodified fiber, while the activity of the oil palm kernel expeller dietary fiber treated with enzymolysis combined with acetylation was not improved. In conclusion, enzymolysis combined with either carboxymethylation or acetylation could enhance the physicochemical properties and hypoglycemic activity of oil palm kernel expeller dietary fiber to a certain extent, with enzymolysis combined with carboxymethylation yielding the best results. This thus expands its application potential in the food industry.

This study investigated whether selenium-containing peptides derived from selenium-rich black beans exert inhibitory effects on α-amylase and evaluated their potential hypoglycemic activity in vitro. Selenium-rich black beans from Guangxi, China, were used as raw materials, and selenium-containing peptides were screened and synthesized through a combination of single-factor experiments, response surface methodology, and peptidomics analysis. Four peptides—Se-MetLP, Se-MetIP, TLTSe-MetLR, and Se-CPSFGQ—were identified and evaluated for their α-amylase inhibitory activity. Among the four peptides, Se-MetIP exhibited the highest inhibitory effect, achieving an inhibition rate of 70.58%±2.21% at a concentration of 4 mg/mL, whereas TLTSe-MetLR showed the lowest half-maximal inhibitory concentration (IC₅₀) of 0.47 mg/mL, indicating superior inhibitory potency. Based on their strong α-amylase inhibitory activity, Se-MetIP and TLTSe-MetLR were selected for further investigation of inhibition mechanisms using circular dichroism spectroscopy, isothermal titration calorimetry, and molecular docking analyses, and their in vitro hypoglycemic effects were subsequently evaluated in a hyperglycemic HepG2 cell model. Circular dichroism analysis revealed that peptide binding induced conformational changes in α-amylase, characterized by increased β-sheet content and reduced β-turn and random coil structures, suggesting alterations in the enzyme spatial conformation. Isothermal titration calorimetry demonstrated that peptide-enzyme interactions were exothermic. Molecular docking results showed that the binding free energies of Se-MetIP and TLTSe-MetLR with α-amylase were −5.399 and −6.401 kcal/mol, respectively, with van der Waals forces and hydrogen bonding as the dominant stabilizing interactions, complemented by hydrophobic effects. Furthermore, cellular assays demonstrated that Se-MetIP and TLTSe-MetLR significantly enhanced glucose consumption and promoted glycogen synthesis in insulin-resistant HepG2 cells, thereby improving glucose utilization. Overall, selenium-containing peptides from black beans effectively inhibit α-amylase activity and exhibit in vitro hypoglycemic potential, providing a theoretical basis for the development of hypoglycemic peptides from selenium-rich black beans.

This study investigated the physicochemical and digestive properties of glycated tilapia scale collagen peptides (G-TSCP) reacted with galactooligosaccharides (GOS) under different thermal processing conditions (80, 100, 120 ℃). The glycation degree was evaluated through analysis of colorimetric parameters (ΔE), pH variation, fluorescence intensity, grafting degree, and furosine level. Structural characterization was performed using Fourier transform infrared spectroscopy (FTIR), while digestibility was assessed through in vitro simulated gastrointestinal digestion coupled with size exclusion chromatography (SEC). Thermal processing analysis revealed significant time-dependent alterations (P<0.05): grafting degree (9.58%±0.23%), ΔE values (4.39±0.13), and fluorescence intensity (502803±8089 Rfu) reached maximum levels at 100 ℃/60 min treatment, while the most pronounced pH reduction (7.55±0.03) occurred at 120 ℃/20 min processing. Significantly positive correlations were observed between grafting degree and ΔE (r=0.83, P<0.01) and fluorescence intensity (r=0.77, P<0.05), while pH was negatively correlated with these parameters (r=−0.81, P<0.01; r=−0.87, P<0.01). Secondary structure analysis indicated that glycation-induced conformational changes were characterized by the decrease of β-turn content (from 46.5% to 24.6%) and the increase of random coil structures (from 12.4% to 33.6%) under the processing condition of 120 ℃/20 min when compared to native TSCP. Digestibility assessments demonstrated that G-TSCP exhibited lower hydrolysis degree (from 22.18% to 68.8%) when compared to native TSCP (P<0.05), with the 120 ℃/20 min processed sample showing minimal intestinal digestibility (6.65%±0.18%). SEC analysis revealed that thermal processing at both 100 ℃ and 120 ℃ significantly enhanced the ratio of 1000~5000 Da fractions in G-TSCP, showing higher proportions than unmodified TSCP. Under optimal heating conditions (100 ℃/40 min), the glycated tilapia scale collagen peptide (G-TSCP) exhibited a grafting degree of 8.07% and a furosine content of 5.83 μg/100 mg TSCP, indicating moderate glycation. Compared to native TSCP, G-TSCP demonstrated significantly reduced gastrointestinal hydrolysis (10.27%) (P<0.05), suggesting enhanced digestibility resistance. These findings reveal that controlled thermal glycation can modulate collagen peptide structure and attenuate digestion, providing a potential strategy for designing sustained-release bioactive peptide formulations.

To enhance the bioavailability of phytosterols and investigate the role of soybean oil bodies in hydrophobic bioactive compound delivery systems, this study utilized whey protein isolate (WPI) and soybean oil bodies (SOBs) as interfacial particles to prepare whey protein isolate-soybean oil body emulsions (WOE) for phytosterol delivery. The effects of varying pH and ionic concentrations on the particle size, Zeta potential, and rheological properties of WOE were investigated systematically, as well as the changes in microstructure, free fatty acid release rate, and phytosterol bioavailability of WOE during the simulated digestion process. The results demonstrated that WOE was an oil-in-water emulsion formed by adsorption of WPI and SOBs at the oil-water interface. At pH4, the Zeta potential of WOE approached 0, indicating that the isoelectric point of WOE was close to 4. WOE exhibited greater stability under alkaline conditions. The rheological results showed that WOE exhibited non-Newtonian fluid properties at different pH and NaCl conditions, and G' was larger than G" at frequencies from 0.1 to 100 Hz, and WOE had an elastic-dominated gel property. During the simulated digestion phase in vitro, the number of large lipid droplets in the WOE gradually decreased as the digestion time increased. During the simulated intestinal fluid digestion, trypsin degraded the fat within the emulsion droplets and released free fatty acids, and the fat droplet size of WOE gradually decreased from 16.85 μm to 7.25 μm, and the release of free fatty acids reached 75.45 μmol/mL in less than 90 min, and the phytosterol bioavailability consistently increased to 72.23%, which was higher than that of free fatty acid release (38.45 μmol/mL) and phytosterol bioavailability (48.08%) in the pure soybean oil group, indicating that WOE had good digestive properties and improved phytosterol bioavailability. This study provides a theoretical reference for hydrophobic bioactivities delivery systems, as well as a basis for the application of novel emulsion systems in food, dietary supplements and drug delivery.

In order to clarify the effects of alkaline covalent binding, enzymatic covalent binding and free radical covalent binding of soybean lipophilic protein (LP) to chlorogenic acid (CA) on the conformational and functional properties of proteins and the mechanism of binding. Accordingly, this study comprehensively employed particle size and Zeta potential analysis, electrophoresis, multispectral techniques, differential scanning calorimetry, rheology, scanning electron microscopy, and antioxidant activity assays to characterize the molecular weight, secondary and tertiary structures, thermal stability, rheological properties, and antioxidant capacity of the complexes under different preparation conditions. The results demonstrated that the polyphenol binding rate of LP increased based on free radical, base and enzyme conditions, and particle size and the absolute values of Zeta potential were higher than those of LP. The content of free amino group and sulfhydryl group decreased, but the content of disulfide bond increased, with the most significant changes observed in the enzymatic complexes. The introduction of CA shifted the electrophoretic bands of LP upward, and the subunits in the LP molecule were denatured into small molecular subunits, with progressively more significant denaturation of the free radical complexes, the alkaline complexes, and the enzymatic complexes. The free radical complexes, enzymatic complexes and alkaline complexes had sequentially increased ionic bonding content and sequentially decreased hydrophobic force compared to LP. The results of circular dichroism and Fourier infrared spectroscopy indicated that CA was successfully complexed with LP, and the two were mainly connected through C-N/C-S bonds, with an elevated content of random coils and a reduced content of β-sheets and β-turns in the complexes, and the most significant changes in the secondary structure of the alkali complexes. The intrinsic fluorescence results indicated that the enzymatic complex exhibited the strongest fluorescence quenching effect, followed by the alkali complex. The surface hydrophobicity of the complexes decreased, and that of the alkaline complexes was the lowest. The thermal stability and rheological properties of the complexes, especially the alkaline complexes, were enhanced. The incorporation of CA resulted in more protrusions and pores on the surface of LP, and the microscopic morphology of the free radical complexes, the enzyme complexes, and the alkaline complexes became more homogeneous and dense. The antioxidant capacity of the LP-CA covalent complexes increased after digestion. The free radical complexes possessed the strongest antioxidant capacity, while the enzymatic complexes had the weakest antioxidant capacity. This study can provide a theoretical basis for the application of LP-CA complexes as functional ingredients and the development of CA-containing soy protein products.

To investigate the photoisomerization mechanism of astaxanthin (AST), the types and contents of Z-configuration in photocatalytic conversion of AST were analyzed by HPLC and Q value method. Additionally, the AST configuration was optimized and frequency analysis was performed using density functional theory (DFT). Thermodynamic, kinetic, and energetic parameters of all-E- and Z-AST isomers were further calculated. The results demonstrated that 9-Z- and 13-Z-isomers were predominantly generated under photocatalysis, with the 13-Z content (17.72%) being significantly higher than 9-Z (13.57%) (P<0.05). Upon illumination, neutral AST molecules generated diradicals, facilitating bond twisting. All-E AST exhibited the smallest frontier orbital energy gap, promoting its transition from the ground state to the excited state, and subsequent isomerization into other configurations. Gibbs free energy analysis revealed the following stability order of AST isomers: all-E>9-Z>13-Z>15-Z, basically consistent with experimental observations. Moreover, the activation energy for all-E→9-Z conversion was higher than for all-E→15-Z/13-Z, while single-Z→double-Z isomerization required significantly higher energy than all-E→mono-Z conversion. Notably, the 13-Z-isomer formation rate was about 4-fold and 100-fold higher than that of 15-Z> and 9-Z, respectively. The negligible tunneling effect during mutual transformation explained the scarcity of multi-Z-isomers in experiments and the predominance of 13-Z over 9-Z AST. Collectively, these findings elucidate the controlled generation mechanism of AST isomers and establish a theoretical framework for carotenoid isomerization.

This study investigated the effects of dynamic high-pressure microfluidization (DHPM) on the structural characteristics and bioactivity of polysaccharides extracted from Dictyophora indusiata (DIP). The physicochemical properties, molecular weight, monosaccharide composition, and Fourier transform infrared (FTIR) spectral features of DIP were systematically analyzed following DHPM treatment. Antioxidant and anti-inflammatory activities were evaluated using DPPH·, ABTS⁺·, and ·OH scavenging assays, ferric ion reducing antioxidant power (FRAP), and an lipopolysaccharide-induced RAW264.7 macrophage inflammation model. Compared with the group that did not undergo DHPM treatment, DHPM treatment significantly increased the polysaccharide yield and total polysaccharide content, by 4.87-fold and 1.23-fold, respectively (P<0.01). It also markedly reduced the weight-average molecular weight and extremely significantly increased the glucose content in the monosaccharide composition (P<0.001), without altering the primary structure, which remained pyranose ring-based. Additionally, DHPM-treated DIP demonstrated enhanced antioxidant activity, including improved scavenging ability of DPPH·, ABTS⁺·, and ·OH and greater ferric ion reducing power. The DHPM treatment also significantly downregulated IL-6 and TNF-α expression in LPS-stimulated RAW264.7 cells (P<0.05), indicating stronger anti-inflammatory activity. In conclusion, DHPM-assisted extraction effectively improves the yield and functional properties of DIP by reducing molecular weight and modifying monosaccharide composition. These findings provide valuable insights for optimizing the extraction and functional utilization of DIP.

This study investigated the impact of a combination of dynamic high pressure microfluidization (DHPM) and cellulase treatment on the structural and physicochemical properties of pea dietary fiber-caffeic acid (PDF-CA) complex. The experimental model involved subjecting PDF-CA to DHPM, followed by the addition of cellulase, with the objective of examining how the combination of DHPM and cellulase influenced the structure and physicochemical properties of PDF-CA. Scanning electron microscopy (SEM) and particle size analysis revealed that the application of DHPM in conjunction with enzyme treatment led to a reduction in the size of the particles in the samples. The surface of the samples exhibited a rough and loose texture, and agglomeration occurred at an enzyme concentration of 3%. Fourier infrared (FT-IR) and X-ray diffraction (XRD) spectroscopy indicated that the modification did not induce any alterations in the crystal structure of PDF-CA. Additionally, no novel functional groups were detected, although the degree of crystalline order diminished. Compared to untreated samples, modified PDF-CA exhibited improved water- and oil-holding capacities, as well as improved glucose and cholesterol adsorption capacities. Water and oil retention significantly increased at a treatment pressure of 60 MPa with two cycles and an enzyme concentration of 1%, rising from 6.4 g/g and 7.9 g/g to 8.9 g/g and 11.1 g/g respectively, representing increases of 39.1% and 40.5%. The glucose adsorption capacity showed the most pronounced increase after a single treatment at 60 MPa with 3% enzyme concentration, rising from 3.9 mg/g to 13.6 mg/g with an increase of 248.7%. The most significant improvement in cholesterol adsorption capacity was observed after three 60 MPa treatments at a 1% enzyme concentration, with increases from 6.6 g/g (pH2) and 6.7 g/g (pH7) to 14.5 g/g and 13.2 g/g representing respective increases of 119.7% and 97.0%. In summary, the combined use of DHPM and enzymatic modification effectively improved the physicochemical properties of PDF-CA, providing theoretical support for its application in modification and processing of dietary fibre-polyphenol complexes.

This study aimed to investigate the enrichment effect of cold atmospheric pressure plasma (CAPP) combined with V_B6 and V_C on gamma-aminobutyric acid (GABA) content enrichment of purple kidney bean germination. The purple kidney beans were used as raw materials. The effects of different concentrations of V_B6 and V_C on the GABA enrichment of germinated beans treated with cold atmospheric pressure plasma as well as the activities of related metabolic enzymes were investigated. The results demonstrated that the method of cold atmospheric pressure plasma treatment with V_B6 and V_C promoted the enrichment of GABA in sprouted purple kidney beans. The GABA enrichment content reached 10.05±0.93 mg/g at 72 h of germination when treated with the CAPP combined with 0.25 mg/mL V_C. The GABA enrichment content reached 10.09±0.06 mg/g at 72 h germination when treated with CAPP combined with 0.5 mg/mL V_B6. Analysis of enzyme activities of germinated purple kidney beans at 72 h revealed that CAPP, V_B6 and V_C treatments enhanced glutamate decarboxylase (GAD) activity while partially suppressing polyamine oxidase (PAO) activity. The combination of CAPP with V_B6 and CAPP with V_C for the germination of purple kidney beans both enriched GABA by enhancing the activity of GAD and suppressing the activity of GABA transaminase (GABA-T). The result showed that the treatment condition had a promotion effect on the enrichment of GABA in the germination of kidney beans, and established a theoretical foundation for the production of high GABA rich food.

In order to compare the differences in typical characterization of bovine milk exosomes between raw milk and liquid dairy products processed by different processing technologies, and to investigate the effects of production process and gastrointestinal digestion on the characterization and transport capacity of bovine milk exosomes, this study selected raw milk, commercial pasteurized milk and ultra-high temperature instantaneous sterilized (UHT) milk as research subjects. The gastrointestinal digestion process was simulated using the international INFOGEST in vitro digestion model. Bovine milk exosomes were isolated using isoelectric precipitation combined with ultracentrifugation. Comprehensive characterization of exosomes was performed by measuring total protein concentration with a BCA protein assay kit, observing morphology by transmission electron microscopy, analyzing particle size distribution by nanoparticle tracking analysis, and detecting specific protein markers (CD9, CD63, and TSG101) by western blotting. Additionally, the uptake of exosomes by bovine mammary epithelial cells (MAC-T) and rat intestinal epithelial cells (IEC-6) was visualized by confocal laser scanning microscopy. The results showed that the total protein concentration of exosomes isolated from equal volumes of raw, pasteurized and UHT milk increased sequentially with significant differences (P<0.05). Exosomes derived from raw milk exhibited significantly larger particle sizes than those derived from pasteurized and UHT milk (P<0.05), whereas no regular pattern was observed in particle size changes induced by simulated gastrointestinal digestion. Both production process and gastrointestinal digestion reduced the integrity of exosomal surface proteins to varying degrees, with UHT milk exosomes showing only weak expression of TSG101 and CD63. All three specific protein markers became undetectable after digestion. Fluorescent tracer experiments revealed no significant differences in the uptake efficiency of bovine milk exosomes by two target cell types (IEC-6 and MAC-T), and exosomes subjected to processing or digestion were still non-specifically internalized by these cells. This study demonstrated that production process and gastrointestinal digestion significantly compromised the characteristic properties of bovine milk exosomes but did not entirely abolish their transport capacity, providing a theoretical foundation for the development of functional dairy products.