Preparation, characterization and in vitro stability of soy protein fibrils ferrous delivery system

Iron deficiency is considered widespread globally, and discovering ferrous ion delivery system with better stability is one of the keys to solving this problem. In this paper, a ferrous ion delivery system was prepared from soy isolate protein fibrils (SPNFs). The alterations in infrared spectrum and microstructure before and after loading were compared, and the ionic strength stability, freeze-thaw stability, and oxidative reaction activity of soy isolate protein fibrils loaded with ferrous iron (SPNFs-Fe) were analyzed, simulating the release kinetics of gastrointestinal digestion. The results demonstrated that SPNFs load ferrous ions with carboxyl, carbonyl, and amino groups. SPNFs-Fe had good ionic strength stability and excellent freeze-thaw stability and showed weak pro-oxidation activity. The release kinetics of SPNFs-Fe in simulated gastrointestinal digestion best fit the Ritger-Peppas model, which had a slow-release effect in simulated gastrointestinal digestion. The release of SPNFs-Fe in simulated gastric fluid belonged to Fick diffusion, while in simulated intestinal fluid it belonged to non-Fick diffusion. These results suggest that SPNFs-Fe is a promising ferrous delivery system as a supplementary source of iron. • Soy protein fibrils successfully loaded ferrous iron. • SPNFs-Fe had good ionic strength stability and freeze-thaw stability. • SPNFs-Fe exhibited low oxidative reaction activity in emulsion. • The release of SPNFs-Fe followed the Ritger-Peppas model. • The release of SPNFs-Fe in simulated gastric fluid belonged to Fick diffusion.