Soluble-protein-aggregate-assisted improvements in heat-induced gel properties: Effect of genipin-mediated crosslinks on egg white protein

• Published in: Food science & technology 2023-07, Vol.184, p.115079, Article 115079
• Main Authors: Koyama, Shota, Kodama, Daisuke, Tsujii, Yoshimasa, Handa, Akihiro
• Format: Article
• Language: English
• Subjects: Crosslinker; Dry-heat treatment; Gardenia blue; Gel strength; Protein complex
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2023.115079

Genipin, a covalent crosslinker, has attracted significant attention from the food industry. Herein, the color, heat-induced gelling properties, and soluble aggregate character of the genipin-treated egg white were investigated to clarify the impact of soluble protein aggregates on the gel properties of egg white protein. After genipin pretreatment, the egg white protein turned dark blue and retained this color after heat-induced gelling. The genipin-pretreated egg white protein gel exhibited up to 2.9-fold and 13% higher breaking strength and strain, respectively, compared to non-treated egg white gel. The gel-breaking strength and strain correlated well with the color, before and after gelling. Gel electrophoresis, size exclusion, and anion exchange high-performance liquid chromatography revealed that a soluble protein aggregate with a negatively charged surface formed during pretreatment. The genipin-treated egg white protein formed a finely structured gel with high breaking strength and strain at all tested NaCl concentrations, indicating that the enhanced negative charge of the surface did not contribute to improving the gel properties. The soluble protein aggregates formed via covalent crosslinking are important for improving gel properties. The proposed method is a novel environmentally friendly method for enhancing the gel properties of egg white protein. •The mixture of genipin and egg white turned dark blue after incubation.•Genipin pretreatment increased the gel-breaking strength by up to 2.9-fold.•The gel-breaking strength correlated well with the color, before and after gelling.•Genipin-pretreated egg white had negatively charged soluble protein aggregates.•Soluble protein aggregates are key to improving gel properties.