Calcium fixation on fortified rice made with various rice varieties

The aim of this study was to evaluate calcium fixation and calcium binding in calcium-fortified rice. Calcium-fortified rice was made by soaking (infusing) rice in a Ca-lactate or Ca-gluconate solution at temperature of 80oC for 20 mins. The rice types used in this study were low-, medium-and high amylose rice, represented by Memberamo, Ciherang and IR-42 rice varieties. Calcium retention in rice was tested by washing and dialysis, and calcium levels in the rice were determined by Atomic Absorption Spectroscopy. Calcium fixation was determined by using an FT-IR infrared spectrometer based on the changes in infrared spectra of the functional groups of-OH and C-O. The research showed that calcium retention in rice after washing was between 86.23-94.38 (Ca-lactate) and 89.37-90.15 (Ca-gluconate), Ca retention after dialysis was between 37.49 to 44.13 (Ca-lactate) and 37.40 to 42.86 (Ca-gluconate). The addition of Ca-lactate or Ca-gluconate to rice caused a decrease in the absorbance value and the absorption band area square at a wave numbers 3425 cm-1 (-OH group) and 1300-1000 cm-1(C-O stretching vibration). Based on these data and the retention of Ca2+ after washing and dialysis, the Ca2+ in fortified-rice was bound by hydrogen bonding to form Ca-hydrate and by ionic-dipole bonding with –OH group of starch molecules, and/or trapping in gelatinized starch. © 2020 The Authors. Published by Rynnye Lyan Resources.