Chiang Mai Journal of Science

“Chaing Mai University (CMU)” purple rice is a variety generated from “Kao Kum” black or purple rice. It has high anthocyanin content. This research aimed to synthesize carboxymethyl flour (CMF) characterization and properties, i.e., the degree of substitution (DS), physical properties, and chemical and thermal properties. Rice flour was treated with different alkaline concentrations; 10% to 40% (NaOH, w/v) in sequential reactions with monochloroacetate (MCA). The results revealed that NaOH concentrations had a significant effect on all of the CMF chemical properties. The optimal condition for achieving the highest anthocyanin content (7.67 mg/g of CMF) and CMF content (88.7%) with 0.25 (DS) was found at 10% (w/v), NaOH. Tg, Tgeland Tm of CMF were approximately at 0.95-1.2 ฐC 81.2-102.7 C and 98.5-102.8 C, respectively. Morphological properties were observed, and smoothness of the CMF granule surface lessened with increasing NaOH concentration.