Impact of High Hydrostatic Pressure on the Gelation Behavior and Microstructure of Quinoa Protein Isolate Dispersions

Abstract

The gelation of 10 w/w % quinoa protein isolate (QPI) dispersions induced by high hydrostatic pressure (HHP) at three pHs (5, 7, and 9) was investigated. HHP was conducted at 20 °C for 15 min at 100, 250, 400, and 600 MPa. Thermally induced gelation (81 ± 2 °C, 30 min) was also conducted as a comparison to HHP. Both thermal and HHP (above 250 MPa) treatments can induce protein gelation, and the viscosity and elasticity of the gels increased with the increase in pressure levels. The gels formed either by heat or HHP treatment at pH 5 exhibit a stronger gel strength and a compact network structure than at pH 7 and 9. Confocal microscopy showed that HHP treatment formed a heterogenous and well-spanned network with large protein aggregates, while heat treatment resulted in a more homogeneous structure. SDS–PAGE revealed that QPI gels were formed by the denaturation and aggregation of 11S globulin.