Forces involved in freeze-induced egg yolk gelation: Effects of various bond dissociation reagents on gel properties and protein structure changes

• Published in: Food chemistry 2022-03, Vol.371, p.131190-131190, Article 131190
• Main Authors: Wang, Ruihong, Zhang, Longyuan, Chi, Yujie, Chi, Yuan
• Format: Article
• Language: English
• Subjects: Bond dissociation reagents; Frozen egg yolk; Molecular forces; Protein secondary structure; Texture properties
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2021.131190

•The presence of β-mercaptoethanol and SDS promotes the formation of frozen egg yolk gel.•The effect of urea concentration on the frozen egg yolk gelation is opposite.•The protein secondary structure is closely related to its texture properties.•Hydrogen bonds is the critical force affecting frozen egg yolk gelation, followed by hydrophobic interactions and disulfide bonds. Urea, sodium dodecyl sulfate (SDS) and β-mercaptoethanol (2-ME) were used to monitor the roles of hydrogen bonds, hydrophobic interactions and disulfide bonds in frozen egg yolk. Yolk samples were prepared with a denaturant, and the textural characteristics, turbidity properties, protein patterns and structures were analysed. The results showed that SDS or 2-ME addition to egg yolk promoted its turbidity and texture properties, but urea changed the turbidity differently. SDS-PAGE results showed that yolk protein patterns with urea slightly reduced the amount of high molecular weight substances, whereas SDS and 2-ME addition increased the amount. ATR-FTIR spectroscopy revealed that the protein secondary structures changed from ordered structures to random coils. The texture properties were correlated with the protein secondary structure, especially β-sheets and β-turns. Thus, the three bond dissociation reagents induced protein denaturation. Hydrogen bonds were the critical force affecting frozen egg yolk gelation, followed by hydrophobic interactions and disulfide bonds.