Discussion of mechanism on monascus red pigments with hydroxyls protected by retrograded maize amylose and amylopectin

The effect of the retrogradation of maize amylose, amylopectin and the adding method of monascus red pigment on the color protection were studied by determining the rest monascus red pigment. The protection mechanism of starch was analyzed by IR, NMR and X-ray diffraction. The results showed that the protective effects of retrogradation of maize amylose and amylopectin on the monascus red pigment were obvious and the retention percentage of monascus red pigment was raised from 38.3% to more than 70% under the 15 h of the UV irradiation. In three stages of starch retrogradation such as pasting, autoclaving and retrogradation, addition of monascs red pigment after autoclaving got the best results. The results of NMR, IR and X-ray diffractions indicated that the pigment was combined with the retrograded starch at the C1 and C6 during the retrogradation and the retrogradation of amylose got the better protective effects because amylose could combine with more pigments.