Studying structural and rheological properties of alginate‐whey protein isolate cold‐set hybrid emulgels at various pH levels

Abstract

AbstractEffects of different pH values (4–7) and whey protein isolate (WPI) concentrations (0.5–1.5%) were evaluated on physical, mechanical, and rheological properties of cold‐set alginate‐based soybean oil hybrid emulgels. The pH value changes were more effective than WPI concentration changes on emulgel properties. According to syneresis and texture profile analysis results, 1% WPI was selected as the optimum concentration. The XRD analysis showed that calcium alginate (CA) emulgel at pH 6 had a different peak at 2θ of 14.8°, likely indicating the highest amount of ion‐bridging and maximum number of junction zones. The homogeneity of CA and CA + WPI emulgels (determined by image entropy analysis) decreased by pH reduction from 7 to 4, which can be related to acid‐induced intermolecular interactions between alginate chains. The rheological properties of CA and CA + WPI emulgels revealed predominant elastic character (G′ > G′′) at different pH values. Creep test results showed that the relative recovery of emulgel prepared at pH 7 and 5 was 18.10 and 63.83%, respectively, suggesting pH reduction contributed to increase in the elastic component of material. The findings of this study can be applied for developing structured cold‐set emulgels as solid fat replacers in meat and dairy products.