Ovomucin may be the key protein involved in the early formation of egg-white thermal gel

Mechanism of ultrasound and tea polyphenol assisted ultrasound modification of egg white protein gel

In order to improve the characteristics of egg white protein gel and the stability of egg white protein gel products. In this work, the changes of the texture, physicochemical properties, secondary structure and microstructure of ultrasound modified egg white protein gel (UEP) and tea polyphenols (TP) assisted ultrasound modification of egg white protein gel (TUEP) with different ultrasonic power (0-360 W) were studied. With the increase of ultrasonic power, soluble protein, surface hydrophobicity and disulfide bonds of TUEP and UEP showed an increasing trend. In particular, with the increase of ultrasonic power, the content of intramolecular β-sheets and α-helices of TUEP showed an increasing trend, and significantly improved the relaxation time and microstructure, thus enhancing TUEP gel stability. In addition, the hardness and water holding capacity (WHC) of TUEP and UEP can be increased by ultrasonic treatment, and when the ultrasonic power reached 120 W, the hardness and WHC reached the maximum. The hardness and WHC of TUEP were significantly better than that of UEP. SDS-PAGE results showed that the peptide chain of protein without being broken under ultrasonic treatment. Ultrasonic treatment can improve the gel strength of egg white protein by promoting the cross-linking of proteins to form a dense gel structure, and egg white protein gel form more disulfide bonds and a more stable gel conformation under TP assisted ultrasound. In conclusion, ultrasound and TP assisted ultrasound modification of egg white protein gel is a reliable technique, which can improve the value of egg white protein in food processing.

Bacteriostatic effects of high-intensity ultrasonic treatment on Bacillus subtilis vegetative cells

The bacteriostatic effects of high-intensity ultrasonic treatment (HIU) on Bacillus subtilis vegetative cells were evaluated, and the related mechanisms were explored using quantitative proteomics. The bacteriostatic effect of HIU on B. subtilis was proportional to the ultrasound treatment time and power, and the number of cultivable B. subtilis cells was decreased by approximately one log (at 270 W for 15 min) or half log (at 90 W for 25 min or 360 W for 5 min). Scanning electron microscopy images and gel electrophoresis results showed that HIU caused the destruction of the cell structure and intracellular protein leakage. In addition, HIU treatment at 270 W for 15 min resulted in the greatest decrease (84.22%) in intracellular adenosine triphosphate (ATP) content. The quantitative proteomic analysis showed that B. subtilis resisted the stress of HIU treatment by regulating the key proteins in physiological activities related to membrane transport (ATP-binding cassette [ABC] transporter), signal transduction (the two-component system), and energy metabolism (the tricarboxylic acid [TCA] cycle). HIU-induced physical damage, stress, and metabolic disorders were the main causes of the bacteriostatic effects on B. subtilis. These findings provide a foundation for the subsequent optimization and potential applications of HIU inactivation of B. subtilis.

Structure and biological activities of glycoproteins and their metabolites in maintaining intestinal health

Glycoproteins formed by covalent links between oligosaccharide and polypeptides are abundant in various food sources. They are less sensitivity to gastrointestinal enzymes, and hence many of them undergo fermentation in the colon by microorganisms. Therefore, the confer various health benefits on the intestinal ecosystem. However, the current understanding of the effect of glycoproteins on intestinal microorganisms and gut health is limited. This is probably due to their heterogeneous structures and complex metabolic programming patterns. The structure and biological activities of glycoproteins and their microbial metabolites were summarized in this review. The metabolic pathways activated by intestinal bacteria were then discussed in relation to their potential benefits on gut health. Food-derived glycoproteins and their metabolites improve gut health by regulating the intestinal bacteria and improving intestinal barrier function, thereby amplifying immune response. The data reviewed here show that food-derived glycoproteins are promising candidates for preventing various gastrointestinal diseases. Further studies should explore the interaction mechanisms between intestinal microorganisms and host metabolites.

Study on the emulsification and oxidative stability of ovalbumin-pectin-pumpkin seed oil emulsions using ovalbumin solution prepared by ultrasound

Pumpkin seed oil (PSO), which is a valuable compound with high nutritional value used for the prevention of various chronic diseases, is prone to oxidation. In this work, small and uniform (su) ovalbumin (OVA) and pectin (PEC) were used to stabilize PSO in the form of an emulsion. The results showed that suOVA-PEC-PSO emulsion with a droplet size of 9.82 ± 0.05 μm was successfully self-assembled from PSO, PEC, and suOVA solution (with a droplet size of 230.13 ± 14.10 nm) treated with 300 W ultrasound, owing to the formation of a more stable interfacial film on the surface of droplets. The interfacial, rheological, emulsifying, and antioxidant properties of the suOVA-PES-PSO emulsions were excellent, owing to the synergistic effects between PEC and suOVA solution. Moreover, the physical stability of the suOVA-PEC-PSO emulsions to salt stress, a freeze-thaw cycle, and heat treatment was also increased and the oxidation of linolenic acid was notably delayed. These results have extended the food-related applications of OVA and PSO, and provide a promising foundation for further exploration of the self-assembly of composite emulsions by small and uniform proteins.