Impact of protein pre-treatment conditions on the iron encapsulation efficiency of whey protein cold-set gel particles

Abstract

This paper investigates the possibility for iron fortiWcation of food using protein gel particles in which iron is entrapped using cold-set gelation. The aim is to optimize the iron encapsulation eYciency of whey protein by giving the whey protein diVerent heat treatment prior to gelation with iron. The eVect of the heat treatment conditions (mild-intermediate-severe) on the iron-induced coldset gelation process was studied to optimize the gel strength in relation to the iron concentration. Rheology was used to study the protein gel formation, and the stability of the gel particles and iron encapsulation eYciency was determined by measuring the protein and iron content at diVerent pH. Both the iron concentration and the heat treatment conditions appear to aVect the gel formation process and gel strength of the iron-induced cold-set gels. With the protein gel particles being stable at a broad pH range, the release of iron from the particles was studied as a function of time. The low release of iron at neutral pH indicated good encapsulation eYciency and capability of whey protein to keep iron bound. At low pH the release of iron increased, as is desired for bio-accessibility. In addition to diVerences in gel strength, the most relevant result caused by the pretreatment of the whey protein is revealed in the amount of iron that can be entrapped per protein. It is shown that the amount of iron can be increased going from mild to severe heat treatment conditions. This suggests that the concept of using whey protein particles with iron can eVectively be used to fortify food products with iron for human consumption.

Lactoferrin-based nanoparticles as a vehicle for iron in food applications – Development and release profile

“…The binding of iron to bLf binding site takes place at pH values around 7. A similar behaviour was observed by Martin and de Jong (2012) during iron release from whey protein isolate (WPI) particles. These authors observed a low release of iron at pH 6.5 indicating a good capacity of WPI to keep iron bound, and an increase of iron release at pH 2.…”

Development of iron-rich whey protein hydrogels following application of ohmic heating – Effects of moderate electric fields

“…In salt-induced gelation of globular whey proteins or whey protein isolate, salts such as NaCl and CaCl 2 are commonly used. Slow addition of these salts to a heat denaturated whey protein solution help to screen the electrostatic repulsion or form salt bridges between negatively charged on proteins and molecules and aggregates, thus facilitating gelation (Ako, Nicolai, & Durand, 2010;Marangoni, Barbut, McGauley, Marcone, & Narine, 2000;Martin & Jong, 2012); gels produced by this method have shown higher strength and water-holding capacity than gels formed by heat-induced gelation (Bryant & McClements, 2000;Nicolai et al, 2011). Iron has also been reported to induce aggregation and gel formation in pre-heated protein solutions (Remondetto, Paquin, & Subirade, 2002;Remondetto & Subirade, 2003).…”

Iron‐encapsulated cold‐set whey protein isolate gel powder – Part 1: Optimisation of preparation conditions and in vitro evaluation

“…However, they did not report either an absolute amount or the percentage of iron entrapped in the protein matrix. Martin and De Jong () observed considerable differences between the mol binding ratio of the protein gel particles prepared by varying the pH, temperature–time and protein concentration during the preheating step. They did not report EE values, but estimated the mol binding ratio using the amount of release of iron and protein at neutral conditions.…”