Analyzing the Effects of Agar Gum on the Textural and Rheological Properties of Cold-set whey Protein Isolate Emulsion-filled Gel

Abstract

This study evaluated the impact of agar gum (AG) (0-0.7% w/w) on the textural, rheological, and held water characteristics of cold-set whey protein isolate emulsion filled gel (EFG). Steady shear results showed that EFGs had a shear-thinning flow behavior, and with increasing AG concentration, the consistency coefficient increased from 339.12 Pa.sn (no AG) to 951.46 Pa.sn (0.7% AG). The amplitude sweep assay illustrated that the AG level had a meaningful effect on the rheological parameters so that GʹLVE, GʹʹLVE, Gf and tF increased, and Tan dLVE decreased with an increase in the AG level. Based on the frequency sweep test, adding AG significantly enhanced the magnitudes of kʹ and kʹʹ, so that their values increased from 5311.80 and 939.90 Pa in the control to 25080.60 and 3574.90 Pa in the 0.7% AG-contained sample, respectively. Also, the parameters of the strength of the network (5380.10-25344.30 Pa.s1/z), the network extension (10.05-15.59) and the extent of departure from the Cox-Merz rule (3476.80 to 21509.44 Pa) increased directly as a result of the rise in AG content. In the composite EFG with 0.7% AG, the highest initial tangent modulus and fracture stress were recorded, which showed lower fracture strain and equal fracture energy in comparison to the control sample. Research results also showed that the held water decreased meaningfully at a high concentration of AG. These results add to the knowledge of the protein-polysaccharide interactions that can be helpful in the production of new functional foods.

Keywords

• agar
• cold set emulsion-filled gel
• fracture properties
• rheology
• whey protein