Effect of quinoa protein concentration and oil volume fraction on the physicochemical and mechanical properties of alginate-based emulsion gels

Background

This work studies emulsion gel (EG) formulation with quinoa proteins (QP), high-oleic sunflower oil and alginate, and the effect of QP concentration (0.5–1–2%) and the oil volume fraction (10–30–50%) on the physicochemical and mechanical properties of EG systems. EGs were tested for their microstructural and textural attributes, color, and water holding capacity as well as for their thermal, physical, and oxidative stability.

Results

The microstructure of EG showed that with increasing QP concentrations, the gel structure tended to be much denser, with oil droplets entrapped within the network. A significant decrease in droplet diameter with increasing QP concentration (p = 0.015) and oil volume fraction (p < 0.000) was observed. Hardness mean value was 2.8 N ± 0.5, reaching the highest value with 1 and 2% QP and 30% oil (p < 0.000). Cohesiveness shows a similar trend to that observed for hardness, while springiness showed the opposite behavior. As for adhesiveness, there were no significant differences between samples. EG have high lightness with slight yellow and green contributions. The mean water holding capacity was 88 ± 4%, and after heat treatment all samples exhibited a good fluid retention, significantly lower for the lower oil volume fraction (p = 0.001). EG, also proved to be highly stable against creaming and oxidative damage.

Conclusion

Results suggest that EG could be useful to create a new generation of healthier and innovative products that could substitute animal fat and deliver nutrients and biological compounds, thus improving food quality.