Chondroitin sulfate (CS), a glycosaminoglycan covalently linked to proteins in proteoglycans, exhibits significant pharmacological activities. However, systematic comparisons of structural and functional differences among CS from diverse sources remain limited. This study comparatively analyzed CS extracted from tilapia heads in our laboratory and commercially available animal sources (bovine cartilage, chicken cartilage, and shark cartilage) using UV, IR, and NMR spectroscopy, and evaluated their antioxidant and hypolipidemic activities through DPPH, ABTS⁺ radical scavenging assays and bile-acid binding tests. Results revealed that tilapia head-derived CS and shark CS shared similar sulfation patterns, predominantly classified as CS-C type (6-O-sulfation), whereas bovine and chicken-derived CS belonged to CS-A (4-O-sulfation). Notably, tilapia CS exhibited the highest ABTS⁺ scavenging capacity (90.72%±0.19%) at 4 mg/mL, while shark CS showed superior cholesterol micelle binding (39.38%±0.86%) at 6 mg/mL. This study revealed that the CS-C type configuration (dominant in tilapia head- and shark-derived CS) exhibited significantly superior antioxidant and lipid-regulating activities compared to the CS-A type (bovine and chicken sources) due to the positional advantage of 6-O-sulfation. This work systematically compared structural and functional divergences between terrestrial and marine-sourced CS, elucidating the critical impact of sulfation sites (C4 vs C6) on bioactivity while highlighting the application potential of marine-derived CS, thereby providing strategic insights for source-specific CS exploitation.

Apple polyphenol oxidase (PPO), a key enzyme triggering enzymatic browning in fruits and vegetables, requires efficient purification for both mechanistic studies and industrial applications. To address the limitations of conventional single precipitants (e.g., high solvent consumption and low enzyme activity recovery), this study aimed to develop a cost-effective PPO purification strategy by integrating mixed solvent precipitation guided by molecular dynamics (MD) simulations with chromatographic techniques. First, MD simulations predicted the interaction mechanisms between PPO and precipitants (ammonium sulfate, ethanol, acetone, and ethanol/acetone mixtures). Further purification was then conducted using DEAE-Sepharose Fast Flow ion-exchange chromatography and Sephadex G-100 gel filtration. The experimental validation demonstrated that the ethanol/acetone mixed solvent precipitant exhibited superior binding affinity. Single-step mixed solvent precipitation (ratio of ethanol/acetone 1:1, v/v) at 50% solvent concentration reduced precipitant usage by 33.33%, while achieving 89.85% enzyme activity recovery and a 1.24-fold purification. After chromatography, the PPO specific activity reached 156362.78 U/mg, with a purification fold of 18.33. SDS-PAGE analysis confirmed a single protein band at approximately 28 kDa. The mixed solvent precipitation approach proposed in this study based on MD provides a novel approach for PPO purification, offering critical implications for advancing enzymatic browning control technologies in fruit and vegetable processing industries.

This study aimed to explore the influence of the combination of chestnut protein (CP) and pomegranate polyphenol (PP) on the properties of Aristichthy nobilis surimi, such as gel texture, rheological features, and microstructure. The results of this study demonstrated that increasing the proportion of PP initially enhanced gel strength and water-holding capacity, but these properties declined at higher levels. As the percentage of PP elevated, gel whiteness showed a tendency to decline, while the cooking loss rate displayed a first reducing and then rising tendency. The lowest cooking loss appeared in the PP1 group, at 5.48%. Gel hardness and chewiness in the PP1 group individually increased by 54.19% and 63.56% in comparison with the control group. It was also found that at a high level of PP, the overall gel texture declined, but at optimal levels, it significantly improved G′ and G″, enhanced rheological attributes, and promoted a dense, compact gel spatial structure. Moreover, adding a proper percentage of PP could also facilitate the transitions in gel proteins, from α-helix to β-sheet and random coil. Compared to the control, α-helix relative content in the PP1 group declined by 13.56%, while the β-sheet and random coil relative contents in the PP1 group separately increased by 9.22% and 12.53%. This research revealed that combining PP and CP could significantly enhance the gel characteristics of the Aristichthy nobilis surimi. These findings in this work can offer an evaluable reference for implementing the combination of plant polyphenols and plant proteins as an approach to improve the gelation quality of freshwater fish surimi.

In this study, a soybean protein isolate (SPI) oleogel system was established based on capillary bridging effect. The influence of the secondary fluid addition, particle concentration, and heat treatment temperature on the gelation properties of the resultant oleogels was explored. The visual appearance, liquid-holding capacity, and rheological properties were investigated. Results showed that, in the SPI-soybean oil suspension with ratio of 3:7 (w/w), when the secondary fluid addition amount reached approximately 25% (w/w), the system underwent a sol-gel transition, shifting from a viscous flowing fluid to a semi-solid state with self-supporting ability. When the secondary fluid addition amount was higher than 50%, the liquid-holding capacity rose to over 60%. As the SPI particle concentration increased, the proportion of particles in the system increased accordingly, resulting in formation of a tighter protein network structure that was more effective at immobilizing the liquid oil. Once the particle concentration surpassed 35%, the liquid-holding capacity climbed to above 75%. Further investigation indicated that heat treatment was an effective post-treatment approach. Specifically, when the heat treatment temperature increased from room temperature to 90 ℃, the liquid-holding rate increased by 11.68% (compared with control group), and the storage modulus increased to 1.43×10⁵ Pa. The FTIR results indicated that heat treatment caused changes in the secondary structure of SPI molecules within the system, with an increase in the β-turns and random coil structures. This suggested that the enhanced gelation properties of the oleogel might be due to the dynamic alteration of the interfacial properties of the protein particles, leading to enhanced hydrophobic interactions in the system and the formation of a more robust gel structure. This work established a theoretical basis for development and property regulation of soybean protein-based fat alternatives and provided guidance for healthy food design.

Protein-polysaccharide complexes exhibit promising functionality as encapsulation wall materials to enhance the stability and bioavailability of bioactive components during delivery. In this work, zein-peach gum polysaccharide (PGP) nanocomposite particles were fabricated via antisolvent precipitation. The interaction mechanisms and microstructure organization of zein-PGP composite nanoparticles were systematically investigated using multi-technique characterization, while their antioxidant capacity and colloidal stability were concurrently evaluated. The results showed that the primary forces driving the formation of nanoparticles between zein and PGP were hydrogen bonding and hydrophobic interactions, which contributed to the stability of the composites. At the meanwhile, the incorporation of PGP significantly enhanced the radical scavenging capacity of the complexes (P<0.05). When the mass ratio of zein to PGP was 1:1, the composite particles exhibited optimal stability, with a particle size of 156.73±5.17 nm, a PDI of 0.15±0.01, and a Zeta potential of −31.43±0.44 mV. The relative contents of α-helix, β-sheet, and β-turn in the composites were 45.0%, 12.0%, and 15.0%, respectively. Additionally, the presence of PGP enhanced the quenching of zein's intrinsic fluorescence. These findings not only provide a new perspective for the combined utilization of zein and PGP but also lay a foundation for future applications of composite nanoparticles in delivering bioactive components in food industry.

Pectin is a highly promising biosorbent for heavy metals, however, its adsorption performance for these metals during human digestion remains unclear. This study aimed to investigate the structural changes of Citrus pectin with varying molecular weights during in vitro digestion and to evaluate its Pb²⁺ adsorption performance. Four Citrus pectins (CP505, CP163, CP51, and CP21) with molecular weights of 505, 163, 51, and 21 kDa, respectively, were prepared using enzymatic hydrolysis combined with ultrafiltration. Their digestive behaviors were analyzed through an in vitro simulated digestion model, which included oral, gastric, and intestinal phases. Structural changes were characterized using Fourier-transform infrared spectroscopy (FTIR), high-performance size-exclusion chromatography coupled with multi-angle laser light scattering and refractive index detection (HPSEC-MALLS-RI), and dinitrosalicylic acid (DNS) assays. The Pb²⁺ adsorption capacity was determined through in vitro simulated adsorption experiments. The results indicated that, in comparison with the oral digestion phase, the molecular weight of pectin was significantly reduced during the intestinal digestion phase (P<0.05) (e.g., a 35.20% decrease was observed for CP21), accompanied by an increase in reducing sugar content (a 40.06% rise for CP21) and a decrease in degree of esterification (a 59.22% reduction for CP21). Furthermore, the smaller the initial molecular weight of pectin, the more pronounced its degradation. In experiments involving Pb²⁺ adsorption, high-molecular-weight pectins (CP505 and CP163) achieved a removal rate of 38.03% for high-concentration Pb²⁺ (700 mg/L) during the oral phase. In the gastric phase, CP163 and CP51 demonstrated removal rates of 68.98% and 70.20%, respectively, for 600 mg/L Pb²⁺. During the intestinal stage, CP163 and CP51 still maintained adsorption efficiencies of 39.05% and 39.63% for 500 mg/L Pb²⁺. The study revealed that medium-molecular-weight pectins (CP163, CP51) demonstrated optimal adsorption performance in the gastrointestinal phases due to moderate degradation, which released active functional groups while maintaining structural stability. This research provides essential insights into the behavior of pectin in the human digestive system and offers a theoretical foundation for the development of oral heavy metal adsorbents.

This study investigated the effects of different powder processing techniques on the physicochemical and structural characteristics of mango powder. Mango powder was treated using conventional grinding (CG), ball milling (BM) and vibratory crushing (VC) methods, yielding seven types of processed mango powder samples: conventional grinding (CG), ball milling samples with different grinding times (1, 2, 3 hours corresponding to BM1, BM2, BM3), and vibratory-crushed samples with different grinding times (1, 7, 15 minutes corresponding to VC1, VC7, VC15). By measuring physicochemical properties such as particle size, moisture content, water activity, and solubility, along with structural characteristics including differential scanning calorimetry and Fourier-transform infrared spectroscopy, the physicochemical and structural properties of mango powder were analyzed. Results showed that both BM and VC treatments significantly modified the physicochemical attributes of mango powder compared to the CG. BM and VC significantly reduced the particle size of the fruit powder. BM decreased the moisture content and water activity of mango powder, whereas VC exhibited an inverse pattern. BM and VC increased the water solubility of mango powder from 53.467% (CG) to 68.230% (BM) and 76.207% (VC), respectively. Based on physicochemical parameters, samples BM2 and VC7, which correspond to the optimal grinding times in the BM and VC groups respectively, were selected. Through the further determination of BM2 and VC7, it was found that the density, fluidity and swelling property of BM2 and VC7 decreased, but they effectively retarded the moisture absorption of mango powder and increased the water solubility and oil holding capacity. As the particle size of mango powder decreased, the peak temperature also decreased. BM2 treatment reduced the content of bound water and semi-bound water in the sample, while VC7 exhibited the opposite effect. No new chemical functional groups were detected in all mango powder, and all X-ray diffraction patterns showed similar profiles. However, BM2 and VC7 induced the formation of hemispherical or irregular structures in the mango powder. In summary, ball milling for 2 h and vibration crushing for 7 min can improve the quality of mango powder.

In this study, heat-induced shrimp surimi gel was prepared from Penaeus vannamei. The effects of heating temperature on the gel's formation properties were evaluated by examining its texture, microstructure, and swelling rate. The results revealed that the storage modulus and loss modulus of the shrimp surimi gels decreased as the heating temperature increased from 20 ℃ to 40 ℃. Furthermore, shrimp surimi underwent a transition from a sol-gel state to a thermally irreversible gel between 50 ℃ and 75 ℃. The textural hardness, breaking force, and breaking distance of the shrimp surimi gel initially increased and then decreased with increasing heating temperature. The highest values were recorded at 89 ℃, with textural hardness of 1225.74 g, breaking force of 158.86 g, and breaking distance of 9.28 mm. The water-holding capacity of the shrimp surimi gels peaked at 94.28% at a heat-induced temperature of 89 ℃, decreasing when the temperature was either raised or lowered from this point. The L^* value of the gel decreased with increasing heating temperature, while the a^* and b^* values increased. No obvious changes were observed in the myosin heavy chain and actin bands of the shrimp surimi gel treated with different heating temperature. A dense and orderly network structure gradually formed in the shrimp surimi gel as the heating temperature increased from 86 ℃ to 89 ℃. However, the network structure was disrupted when the heating temperature was further increased beyond 89 ℃. Additionally, the swelling rate of the shrimp surimi gel increased from 32.89% to 118.97% as the heating temperature rose from 86 ℃ to 98 ℃. Therefore, the shrimp surimi gel prepared at 89 ℃ exhibited optimal textural properties and a stable network structure.

To investigate the effects of sodium selenite on the growth, development, and antioxidant activity of highland barley sprouts, highland barley variety Zangqing 2000 was used as the experimental material. Highland barley seeds were soaked in various concentrations of sodium selenite solutions. The study examined the effects of these sodium selenite treatments on germination rate, germination potential, plant height, fresh weight, total selenium and organic selenium contents, as well as total phenolic and flavonoid contents and antioxidant activity in highland barley sprouts. When treated with 5 mg/L sodium selenite, highland barley sprouts achieved the highest germination rate and germination potential, while sprout plant height and fresh weight reached maximum values. Treatments with 5~80 mg/L sodium selenite significantly increased total selenium and organic selenium contents. Total phenolic and flavonoid contents peaked at 40 mg/L and 10 mg/L sodium selenite treatments, respectively, increasing by 8.53% and 16.41% compared to the control group. The ferric reducing antioxidant power and ABTS⁺ free radical scavenging ability reached their highest levels at 10 mg/L, with concurrently high DPPH free radical scavenging ability, increasing by 11.85%, 12.85% and 11.90% compared to the control group, respectively. The antioxidant activity of highland barley sprouts showed a positive correlation with total phenolic and flavonoid contents. In summary, a treatment concentration of 10 mg/L sodium selenite was identified as optimal, significantly enhancing the quality of highland barley sprouts by synergistically promoting both sprout growth and antioxidant activity. The findings provide theoretical and technical references for selenium-enriched production of highland barley sprouts in the Tibetan region.

This research investigated the alterations in functional properties and flavor quality of blueberry-collagen peptide beverage under different fermentation times (0~48 h). The fermented beverage was produced through yeast fermentation using blueberry and cod skin collagen peptides. Subsequent analyses involved determining the nutrient composition (polyphenols, flavonoids, anthocyanins), digestive enzyme inhibitory activity (α-amylase and lipase), and free radical scavenging rate of the beverages. Meanwhile, gas chromatography-ion mobility spectrometry (GC-IMS), electronic tongue, electronic nose, and sensory evaluation were employed to assess the flavor modifications of the beverages throughout the fermentation process. The results revealed that the beverage attained peak levels of polyphenols (1.40 mg∙mL⁻¹) and flavonoids (1.22 mg∙mL⁻¹), with an anthocyanins retention of 0.043 mg∙mL⁻¹ after fermentation for 36 h. The free radical scavenging rate exceeded 80%, while the α-amylase and lipase inhibition rates were 55.17% and 43.69%, respectively. The GC-IMS analysis showed notable increases in esters such as methyl propionate, isoamyl acetate, and ethyl caproate, as well as alcohols like isoamyl alcohol, isobutanol, and n-propanol, whereas sulfide-containing compounds such as allyl isothiocyanate and diethyl trisulfide exhibited decreased levels. These results demonstrated that the blueberry-collagen peptide beverage, after 36 h of fermentation, significantly enhanced active component content, antioxidant capacity, and digestive enzyme inhibitory activity. The production of fruity esters/alcohols and the degradation of sulfur-containing off-flavor substances were promoted. By optimizing fermentation time to regulate the directional accumulation of yeast metabolites, this research achieved synergistic optimization of functional properties and flavor quality, presenting a novel approach for enhancing the value of blueberry resources and advancing the development of collagen-based beverages.