Drying Method–Dependent Alterations in Protein Structure, Gastrointestinal Digestibility, and Peptide Profiles in Penaeus vannamei

Effects of Native and Modified Starches on the Structure, Flavour, and In Vitro Digestion Kinetics of Luncheon Meat

To explore the performance of native and modified starches in room-temperature luncheon meat processing, this study prepared samples using seven types of starch (each added at 5%) under consistent formulations and processing conditions. Texture, cooking loss, pH and proximate composition were measured. Partial Least Squares Discriminant Analysis (PLS-DA) combined with electronic nose analysis was applied to differentiate samples, and sensors with Variable Importance in Projection (VIP) values > 1 were selected as key variables. Subsequently, an in vitro digestion simulation was conducted, and the release profiles of reducing sugars and proteins were fitted using a first-order kinetic model. Finally, statistical and correlation analyses among multiple indicators were performed.The results showed that starch type significantly affected the hardness, cooking loss rate, and pH of luncheon meat, although the variation in pH among treatments was relatively small. The selected S4 and S5 sensors contributed most to sample discrimination. The first-order digestion rate constants obtained from kinetic fitting differed significantly among treatments. Spearman correlation analysis revealed significant associations among texture properties, key flavour sensor signals, and digestion kinetic parameters. Overall, different starches exhibited distinct functional roles in luncheon meat, providing theoretical support for the scientific optimisation of starch application in room-temperature meat products.

Methodological approaches to assess protein digestibility with an emphasis on plant-derived foods.

Temperature-Mediated Structure–Functionality Changes in Soybean Meal Protein via Extrusion

Soybean meal protein, a byproduct of soybean processing, has limited functional properties such as emulsifying performance, which restricts its application in foods. Given that high-temperature extrusion tends to cause excessive denaturation and irreversible aggregation, this study aimed to investigate the effects of relatively low extrusion temperatures (85–105 °C) on the structural and functional properties of soybean meal protein. The results showed that extrusion altered the molecular structure and functional characteristics of the protein. With increasing extrusion temperature, the β-sheet content increased while the α-helix content decreased in the secondary structure, and tertiary structural rearrangements occurred, with hydrophobic groups being exposed and subsequently buried. At 95 °C, the protein formed a relatively porous and loose microstructure and exhibited the strongest surface hydrophobicity, water-holding capacity, oil-holding capacity, and emulsifying properties; at 100 °C and above, excessive aggregation occurred, pore structure collapsed, and functional properties declined. Meanwhile, extrusion generally reduced protein solubility. Therefore, 95 °C is identified as the optimal extrusion temperature under the conditions of this study. In addition, this study reveals the correlation between structural reconstruction and functional changes of soybean meal protein, providing a theoretical basis for its high-value utilization and application in the food industry.

Broccoli byproducts protein concentrate: Microwave treatment effect on functional, thermal, and structural properties.

Inspired by the exploration of underutilized byproducts to address food security concerns, broccoli byproduct protein concentrate (BBPPC) was subjected to microwave treatment to enhance its properties for broader food applications. The study examined the effects of varying power levels (270, 450, and 630 W) and a fixed processing time of 90 s on the conformation, physicochemical attributes, and functional properties of BBPPC. The findings revealed that microwave treatment led to modifications in the spatial structure of BBPPC, significantly enhancing its functional properties. SDS-PAGE showed the presence of RuBisCO (Small and large subunit), prolamin and glutelin, whereas amino acid profiling indicated transient exposure and subsequent burial of buried residues. Secondary structure analysis showed an initial decrease then increase in β-sheet content, with random coil content rising then falling, reflecting initial protein unfolding followed by refolding. Intense heating cleaved disulfide bonds into free sulfhydryl groups, which later reformed, facilitating intermolecular aggregation of BBPPC. Notably, the average particle size reduced from 647.7 nm to 336.5 nm at a power of 450 W for the specified duration. The functional properties improved significantly (p < 0.05), with a maximum water absorption capacity of 2.89 g/g, oil absorption capacity of 3.72 g/g, foaming capacity of 89.36%, foam stability reaching 58.49%, and emulsification activity index and stability index at 6.56 m2/g and 64.4 min, respectively. These results provide a theoretical foundation for the utilization of BBPPC and illustrate the effectiveness of microwave treatment in modifying plant proteins.

Functional and molecular characterization of proteins from fermented and coagulated soybean-based foods

Structural Characterization, Physicochemical Stability, and Antioxidant Activity of Rice Glutelin Hydrolysates

Rice glutelin hydrolysates (RGHs) with different degrees of hydrolysis (DH) were prepared using papain, and the structural characterization, physicochemical stability, and antioxidant activity of RGH were analyzed. Results showed that RGH primarily consisted of low molecular weight (MW) peptides (<3 kDa), with hydrophobic/aromatic amino acid content increasing with DH. Higher DH level led to reduced average particle size and zeta potential of RGH. Structurally, as DH increased, a decrease in α-helix content alongside increased β-sheet/random coil ratios was observed in RGH, indicating a transition towards a more disordered structure in RGH. Furthermore, the antioxidant activity of RGH was significantly enhanced with the increase in DH, with RGH-18 showing the highest bioactivity. RGH maintained stability and antioxidant capacity under gastrointestinal digestion as well as various environmental stresses, including varying pH and temperatures, and the presence of metal ions. Cellular experiments demonstrated that RGH-18 alleviated H2O2-induced oxidative damage in HepG2 cells, likely by inhibiting Keap1 and activating Nrf2 via the Keap1/Nrf2 pathway. This study supports the potential of RGH as a functional ingredient and provides insights for targeted rice peptide production.