Soy Protein Pressed Gels: Gelation Mechanism Affects the In Vitro Proteolysis and Bioaccessibility of Added Phenolic Acids

Effects of Matrix Structure on Protein Digestibility and Antioxidant Property of Different Soybean Curds During In Vitro Digestion

This study compared the three most common types of tofu (soybean curd), which were prepared by using magnesium chloride (MgCl2 tofu), calcium sulfate (CaSO4 tofu), and glucono-δ-lactone (GDL tofu) coagulants. The results showed that GDL tofu had a higher water holding capacity than MgCl2 tofu and CaSO4 tofu, which was attributed to its high surface hydrophobicity and disulfide bond content. GDL tofu possessed the lowest firmness, gumminess, and chewiness, along with a uniform network structure and a thin protein matrix. In contrast, MgCl2 tofu exhibited an inhomogeneous network structure with a thick protein matrix. Combining the results of protein hydrolysis degree, SDS-PAGE, and free amino acids during in vitro digestion, it was indicated that the degree of protein digestion in GDL tofu was the highest. After intestinal digestion, GDL tofu had the highest total phenolic content, ferric reducing antioxidant power, and DPPH value. These results demonstrated the superior protein digestibility and antioxidant property of GDL tofu during in vitro digestion due to its structural characteristics that facilitate enzyme diffusion in the matrix. The findings offer insight into the protein digestibility and antioxidant properties of different types of tofu during digestion from structural characteristic perspective and valuable reference information for consumer dietary nutrition.

Delivering Phenolic Acids in Soy Protein Gels: Noncovalent Interactions Control Gastrointestinal Bioaccessibility

This study aimed to explore how the delivery of added phenolic acids was affected by the soy protein gel matrix using the INFOGEST static in vitro digestion protocol. Gels were prepared by two consecutive heating steps and by adding glucono–$$\delta$$ δ –lactone (GDL) as an acidifier or magnesium sulphate (MgSO$$_{4}$$ 4 ) as a salt coagulant. The addition of phenolic acids in GDL gels doubled their elastic modulus (G’) (p<0.05), without showing the same effect on MgSO$$_{4}$$ 4 gels. Nevertheless, the bioaccessibility of phenolic acids was not significantly different between the gel matrices (p>0.05). The release of all phenolics was almost complete (>80%) at the oral phase (pH 7) and significantly lower at gastric phase (pH 3), then at intestinal phase, the release was either increased or significantly reduced depending on the phenolic acid structure. The results of this study suggest that the bioaccessibility of the added phenolic acids is controlled by their interactions with the soy protein gels rather than the protein digestion kinetics of the gels.

New Insights into Cheese Microstructure

Microscopy is often used to assist the development of cheese products, but manufacturers can benefit from a much broader application of these techniques to assess structure formation during processing and structural changes during storage. Microscopy can be used to benchmark processes, optimize process variables, and identify critical control points for process control. Microscopy can also assist the reverse engineering of desired product properties and help troubleshoot production problems to improve cheese quality. This approach can be extended using quantitative analysis, which enables further comparisons between structural features and functional measures used within industry, such as cheese meltability, shreddability, and stretchability, potentially allowing prediction and control of these properties. This review covers advances in the analysis of cheese microstructure, including new techniques, and outlines how these can be applied to understand and improve cheese manufacture.