Effects of pH-Shift Processing and Microbial Transglutaminase on the Gel and Emulsion Characteristics of Porcine Myofibrillar System

Protein-Stabilized Emulsion Gels with Improved Emulsifying and Gelling Properties for the Delivery of Bioactive Ingredients: A Review

In today's food industry, the potential of bioactive compounds in preventing many chronic diseases has garnered significant attention. Many delivery systems have been developed to encapsulate these unstable bioactive compounds. Emulsion gels, as colloidal soft-solid materials, with their unique three-dimensional network structure and strong mechanical properties, are believed to provide excellent protection for bioactive substances. In the context of constructing carriers for bioactive materials, proteins are frequently employed as emulsifiers or gelling agents in emulsions or protein gels. However, in emulsion gels, when protein is used as an emulsifier to stabilize the oil/water interface, the gelling properties of proteins can also have a great influence on the functionality of the emulsion gels. Therefore, this paper aims to focus on the role of proteins' emulsifying and gelling properties in emulsion gels, providing a comprehensive review of the formation and modification of protein-based emulsion gels to build high-quality emulsion gel systems, thereby improving the stability and bioavailability of embedded bioactive substances.

Trace the difference driven by unfolding-refolding pathway of myofibrillar protein: Emphasizing the changes on structural and emulsion properties

The effective strategy of pH-shifting to improve the emulsifying properties of myofibrillar proteins (MPs) extracted from pale, soft and exudative (PSE)-like chicken was investigated. To determine the mechanism of improvement, changes on structural and physicochemical properties were clarified by tracing the difference driven by unfolding-refolding process. According to the results of tryptophan fluorescence intensity and circular dichroism spectroscopy, it is found that unfolding-refolding process markedly changed MPs secondary and tertiary structure. The atomic force microscopy images showed MPs appeared to have fibrous-like appearance at pH 7.0, however, exhibited as spherical shape after pH-shifting. Both emulsifying activity index and emulsifying stability index increased after pH-shifting. These results systematically illustrated the changes on structural and emulsion properties of MPs during unfolding-refolding process. It proved that the strategy pH 11.0-7.0 could more effectively promote MPs emulsifying properties, whose mechanism was simultaneously the transformation in MPs structure and potentially formation of highly-soluble particle.

Modification of structure and functionalities of ginkgo seed proteins by pH-shifting treatment

Modification and improvement of protein functionalities are important for expanding the applications of proteins in food. The objective of this study was to investigate the effects of pH-shifting treatments on the structural and functional properties of ginkgo seed protein isolate (GSPI). GSPI was exposed to acidic (pH 2.0-4.0) and basic (pH 10.0-12.0) pHs for 0, 0.5, 1, 2, and 4 h and subsequently neutralized for refolding. The pH-shifting treatments significantly increased GSPI solubility by 43-141% except for the treatment at pH 2.0, which decreased protein solubility by 16-39%. All pH-shifting treatments more than doubled the surface hydrophobicity of GSPI and significantly improved the emulsifying activity. The highest emulsifying activity was observed in the pH 2.0-treated GSPI, which was 4.9-fold higher than the control. Acid-induced GSPI degradation likely promoted protein adsorption to the oil-water interface. In summary, the pH-shifting-modified GSPI may serve as a promising emulsifier in various food systems.