Effect of high-pressure treatment and germination on the functional, rheological, and microstructural characteristics of red quinoa (Chenopodium quinoa) gels

This study investigates the effect of germination and high-pressure (HP) treatment on the functional and gelling behaviour of red quinoa (RQ) (Chenopodium quinoa). The grains were subjected to germination for 48 hr followed by the application of four pressures (200, 300, 400 and 500 MPa) as well as their combinations to germinated quinoa (GQ) samples. The samples were ground, and the flour was analysed for functional, rheological, and microstructural attributes. Germination and HP treatment improved the functional and gelling properties of RQ samples significantly. The degradation of protein, fat, and starch-lipid complex of the flour led to an increase in the swelling capacity of flour. The treatments increased the oil absorption capacity from 50.02 ± 0.47 to 80.86 ± 0.88 % and emulsification capacity from 57.85 ± 0.71 to 64.17 ± 0.53 %. This increase is attributed to the dissociation and unfolding of polypeptides that expose the hydrophobic sites of amino acids. The decrease in least gelling capacity from 18 to 14% signified a decrease in the amount of flour required for the gelation. Rheometric and texture profile analysis demonstrated an improved gel strength. Moreover, the SEM micrographs showed an increased structure density and reduced porosity which further support the improved gel strength. The study would help to widen the scope of accommodating RQ flour as a gelling or thickening agent in the food industries.