Effect of physiological pH on the molecular characteristics, rheological behavior, and molecular dynamics of κ-carrageenan/casein

Frontiers in Nutrition

Nutrition

Luan Lin¹  Siliang Zhu¹  Peilin Chen²  Juanjuan Guo³  Jie Zhang⁴  Zhiyu Liu⁵ 

[1] College of Oceanology and Food Sciences, Quanzhou Normal University, Quanzhou, Fujian, China;College of Oceanology and Food Sciences, Quanzhou Normal University, Quanzhou, Fujian, China;Fujian Province Key Laboratory for the Development of Bioactive Material from Marine Algae, Quanzhou Normal University, Quanzhou, Fujian, China;College of Oceanology and Food Sciences, Quanzhou Normal University, Quanzhou, Fujian, China;Fujian Province Key Laboratory for the Development of Bioactive Material from Marine Algae, Quanzhou Normal University, Quanzhou, Fujian, China;Key Laboratory of Cultivation and High-Value Utilization of Marine Organisms in Fujian Province, Xiamen, Fujian, China;Fujian Province Key Laboratory for the Development of Bioactive Material from Marine Algae, Quanzhou Normal University, Quanzhou, Fujian, China;State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China;Key Laboratory of Cultivation and High-Value Utilization of Marine Organisms in Fujian Province, Xiamen, Fujian, China;

关键词: κ-carrageenan;    casein;    gastrointestinal pH;    molecular dynamics simulation;    conformational transition;   

DOI  :  10.3389/fnut.2023.1174888

 received in 2023-02-27, accepted in 2023-03-22,  发布年份 2023

来源: Frontiers

【 摘 要 】

IntroductionDuring gastrointestinal digestion, κ-carrageenan (κ-CGN) undergoes physicochemical changes, which associated with the risk of colitis.MethodsTo understand the effect of physiological pH on the conformational transition and binding stability of κ-CGN and κ-carrageenan/casein (κ-CC), we conducted experiments at pH 3.0 (gastric environment) and pH 7.0 (intestinal environment). We evaluated zeta potential, free sulfate group content, Fourier transform infrared spectroscopy, thermodynamic properties, microstructure, and molecular mechanism.Results and DiscussionOur results revealed that the helical conformation of κ-CGN and κ-CC were more ordered and stable, and sulfate group exposure both lower in the intestinal environment (pH 7.0). However, in gastric environment (pH 3.0), the charge density of κ-CGN decreased, accompanied by random curling conformation and free sulfate group content increased. In contrast, the intermolecular interactions between κ-CGN and casein increased in gastric acid environments due to casein flocculation and secondary structure folding, and significantly reduced the exposure of free sulfate groups of κ-CGN. Our research results provide an important theoretical basis for elucidating the molecular mechanism and structure-activity relationship of κ-CGN under casein matrix to protect the mucosal barrier and inhibit colitis, and are of great significance for guiding and expanding the safe application of κ-CGN, thus assisting food nutrition to be absorbed.

【 授权许可】

Unknown   
Copyright © 2023 Guo, Zhu, Chen, Liu, Lin and Zhang.