Iron Availability from Whey Protein Hydrogels:  An in Vitro Study

Abstract

The influence of whey protein hydrogel microstructure, filamentous versus particulate, on iron delivery was studied under different conditions, including simulated gastrointestinal conditions. Experiments were initially conducted to determine the impact of pH and enzymes on iron release. The results show that different iron release profiles can be obtained from filamentous and particulate gels. Particulate gels released more iron than filamentous gels at acidic pH, but the opposite was observed at alkaline pH. In the presence of pepsin at pH 1.2 or pancreatin at pH 7.5, both gel types showed increased protein hydrolysis, but only filamentous gels showed increased iron release, suggesting that matrix structure plays an important role in iron delivery. A dissolution test was carried out under gastrointestinal conditions to mimic the in vivo dissolution process. Filamentous gel released most of its iron during the intestinal phase of a simulated digestion, hence protecting iron during its transit in the gastric zone. Absorption of iron by the Caco-2 system, used to estimate intestinal absorption, revealed that filamentous gels favored intracellular iron absorption. These results suggest that filamentous gels show promise as matrices for transporting iron and promoting its absorption and therefore should be of major interest in the development of innovative functional foods.

Novel Iron-Whey Protein Microspheres Protect Gut Epithelial Cells from Iron-Related Oxidative Stress and Damage and Improve Iron Absorption in Fasting Adults

“…The denatured WP in our formulation is an attractive matrix for the formulation of iron because it has low immunogenicity compared to other milk protein fractions when denatured, does not contain lactose, is biocompatible, and can form gel particles in the presence of iron, thereby modifying the unpleasant metallic taste that is associated with iron [19,20,32]. With regard to their composition and properties, previously reported Iron-WP formulations differ from the formulation that we used, and they have different characteristics of intestinal release.…”

“…This measure represents the maximum increase in serum iron over the specified period, and was chosen because it helps account for the high (65%) intra-individual and between-day variability in fasting morning serum iron [20]. Secondary end points included the comparison of test articles with the following measures: change in serum iron at 2, 4, and 6 h; TPR difference (TPD) or peak serum iron increase; serum iron bioavailability (measured as area under the curve using the trapezoidal rule); change in UIBC; and TSAT level (TSAT %).…”

“…Several groups have evaluated whey protein (WP) hydrogels as carriers for iron [19,20], although none has been tested clinically. The purpose of this work was to characterise and clinically evaluate a novel, amorphous formulation of microspheres of iron in denatured WP, which has shown features predictive of high pharmacokinetic oral bioavailability.…”

Effect of Neutrase, Alcalase, and Papain Hydrolysis of Whey Protein Concentrates on Iron Uptake by Caco-2 Cells

“…calcium in 60 casein (4)(5)(6)(7). Proteins and peptides, mainly from milk and meat, enhance iron 61 absorption were also reported (8)(9)(10). It was summarized that these enhancers had 62 similar characteristics as: 1) contain some of "specific" amino acids, such as Pro, Phe, 63 accordant and the exact effect and mechanism were uncertain yet (10,11); 2) presence 65 of sulphydryl (-SH) groups.…”

Cold-set whey protein microgels containing immobilised lipid phases to modulate matrix digestion and release of a water-soluble bioactive

“…Simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were prepared as described by the US Pharmacopeia (United States Pharmacopeial Convention Council of Experts, 2004), and as per the methods of Remondetto et al (2004) and Maltais et al (2009). SGF was prepared by an addition of 2 g sodium chloride and 7 ml of 37% hydrochloric acid diluted to 1000 ml with distilled, deionised water.…”