Heat-induced gelation of egg white proteins depending on heating temperature: Insights into protein structure and digestive behaviors in the elderly in vitro digestion model

• Published in: International journal of biological macromolecules Vol. 262; no. Pt 2; p. 130053
• Main Authors: Lee, Seonmin, Jo, Kyung, Jeong, Seul-Ki-Chan, Jeon, Hayeon, Kim, Yea-Ji, Choi, Yun-Sang, Jung, Samooel
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2024
• Subjects: absorption; cohesion; digesta; digestible protein; digestion; egg albumen; Egg protein; Elderly; fluorescence; gelation; gels; hardness; hydrophobicity; Protein digestibility; protein structure; temperature; tryptophan; Protein digestibility; Elderly; Egg protein
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.130053

This study investigated the effects of heating temperature of egg white gels (EWGs) on the digestive characteristics by heating egg white (EW) to reach 75 °C (EWG-75) and 95 °C (EWG-95). The gel protein structure showed a decrease in the maximum tryptophan fluorescence intensity and a significant increase in the surface hydrophobicity of EWGs compared to EW (P < 0.05). The total and reactive free sulfhydryl groups were higher in the EWGs than in the EW (P < 0.05). While the proportions of α-helical and β-sheet structures remained similar in EW and EWG-75 (P > 0.05), EWG-95 exhibited a notable decrease in α-helix content (P < 0.05) and an increase in β-sheet content (P < 0.05). Furthermore, EWG-95 displayed higher hardness and cohesiveness than EWG-75 (P < 0.05). In the adult and elderly in vitro digestion models, EWG-95 exhibited the highest protein digestibility (50.44 % and 54.65 % in the models of elderly and adult subjects, respectively) after GI digestion (P < 0.05), followed by EWG-75 and EW. The electrophoretogram of the digesta revealed more intense protein bands in the elderly digestion model, particularly in the gastric digesta of EW, indicating slower digestion compared to the adult model. Therefore, EW should be appropriately heated before consumption, especially for elderly individuals, to facilitate efficient protein digestion and absorption. •Egg whites show significant alterations when heated at 75 °C and 95 °C.•Structural changes in proteins were more pronounced at 95 °C than at 75 °C.•Heating improved the protein digestibility of egg white proteins.•In vitro digestive patterns of egg white gels differed depending on the temperatures.•Egg whites should be heated properly before consumption, especially by the elderly.