Effects of chicken myofibrillar protein concentration on protein oxidation and water holding capacity of its heat-induced gels

The effects of chicken myofibrillar protein (MP) concentrations (20, 40 and 60mg/mL) on MP oxidation and the subsequent effects on water holding capacity (WHC) of heat-induced gels were investigated. MP oxidation stressed by a hydroxyl radical-generating system (10 mu M FeCl3, 0.1mM ascorbic acid, and 1mM H2O2) was evaluated by carbonyl content. Water distribution, microstructure visualization, free sulfhydryl (FSH) groups and molecular forces of the gels were determined to illustrate the effects on WHC. Compared to the non-stressed group, the stressed proteins were highly oxidized where the carbonyl content (p<0.01) increased with decreasing MP concentrations (increased by 24.67% at 20mg/mL). As the MP concentrations were decreased, the percentage of immobile water (decreased by 8.01% at 20mg/mL, while increased by 5.98% at 60mg/mL), ionic bonds, hydrogen bonds, and FSH groups (p<0.05) of the oxidized gels were decreased, the gel network of the oxidized groups was impaired which was with more cracks and protein aggregates, the hydrophobic interactions (increased by 24% at 20mg/mL) and the percentage of free water (p<0.05) (increased by 7.80% at 20mg/mL, but decreased by 6.13% at 60mg/mL) of the oxidized gels were enhanced, and the resultant WHC was reduced (decreased by 17.75 and 8.07% at 20 and 40mg/mL, respectively, but increased by 8.54% at 60mg/mL). The results indicated that the MP concentration could be a potential influencing factor that affected the protein oxidation and subsequently affected the WHC of gels.