Physicochemical and functional properties of modified quinoa starch with adipic acid and acetic anhydride mixture

In this research, quinoa starch samples were evaluated in 9 treatments with different proportions of adipic acid and acetic anhydride mixture (ratio 1 to 30), along with a control sample in terms of physicochemical and functional characteristics and determining the optimal conditions for chemical modification. The mentioned treatments were designed by 3 independent variables affecting chemical modification, including chemical modifier concentration (2%, 4% and 6%), suspension pH (8, 8.5 and 9) and reaction time (60, 90, 120 minutes) by Taguchi method. became The swelling power and water absorption capacity of sample T2 (modifier concentration 2%, suspension pH 9 and reaction time 120 minutes) significantly increased compared to the control sample, which is a sign of the formation of crosslinks along with the formation of stable three-dimensional gel networks. Spectroscopy results showed that except for T2 sample, the rest of the samples had a slight tendency to retrogradation, which was a sign of the high stability of the said sample during the retention period to syneresis (p<0.05). Acetylation significantly improved the solubility characteristics compared to the control sample due to the better dispersion of starch in the aqueous medium. With the increase in the modifier concentration, the stability of the samples against the freeze-thaw cycle decreased significantly (p<0.05). The investigated parameters in measuring the thermal characteristics of modified quinoa starch were evaluated with a significant difference more than the control sample. The apparent viscosity of the T2 sample at the shear speed of 20, 50 and 100 rpm increased significantly compared to the control sample, but the other samples showed a lower viscosity. Also, using Taguchi analysis, the optimal treatment of modified quinoa starch with 2% modifier concentration, suspension pH 9 and reaction time 120 minutes was determined.