Abstract:
In this study, three commercial genotypes of quinoa (black, white and red quinoa) were pressureprocessed at up to 600 MPa, and one genotype of quinoa (black) was modified by ultrasound treatment for up to 19.6 h with a power output of 250 W. The physicochemical properties of native and treated quinoa sample were studied. Samples processed at 500-600 MPa exhibited much lower swelling power (SP), peak viscosity (PV), enthalpy of gelatinisation (ΔH), hydrolysis rate, softer gel texture, higher water solubility index (WSI) and gelatinisation temperatures than those of other samples. The decrease in ΔH suggested that the ordered structure was disrupted, while the decrease in SP and increase in gelatinisation temperatures indicated that the intragranular-bonded force was reinforced. Retrogradation was not affected by HP treatment. Some antioxidant behaviours were facilitated after treatment, and some were not affected. The colour properties were changed after treatment. The SP, PV, gel hardness, gelatinisation temperatures, ΔH and antioxidant activities of samples tended to decrease with prolonged treating time, while the WSI and maximum hydrolysis rate of samples displayed an opposite trend. The decrease in ΔH suggested the crystallite regions of starches were deformed by high pressure (HP) treatment. These properties of samples sonicated for ≥ 4.8 h significantly differed from those of the native sample. The recrystallisation of amylopectin was not affected by sonication, and the colour properties varied with sonication time.
