Effects of Lipids, Amino Acids, and Beta-Cyclodextrin on Gelatinization, Pasting, and Retrogradation Properties of Rice Starch.

The primary purpose of this study was to determine the addition of lipids, amino acids, and beta-cyclodextrin effects on commercial rice starch gelatinization, pasting, and retrogradation properties by using differential scanning calorimetry (DSC), rapid visco analysis (RVA), and x-ray diffractometry (XRD). Analyses from commercial rice starch showed that the presence of 0.6% monopalmitin (MP) increased the peak viscosity (PV), minimum viscosity (MV), and final viscosity (FV) by 38, 27, and 72 RVU respectively. The pasting temperature was also increased by 6°C, whereas the total setback (TSB) was increased by 45 RVU. Incorporation of lysophosphatidylcholine (LC) and lysophosphatidylethanolamine (LE) also showed strong influence on pasting properties of commercial rice starch. Charged amino acids showed a more significant influence on starch pasting properties than the neutral amino acids. Addition of 6% aspartic acid decreased the MV, FV, and TSB by 39, 63, and 25 RVU respectively, whereas the breakdown (BKD) was increased by 33 RVU. The presence of 6% glutamic acid showed a similar pattern to the aspartic acid. However, the presence of 6% arginine and lysine reduced the pasting temperature up to 15°C. Lipid removal from white rice flour reduced the FV and TSB by 48 and 53 RVU, respectively. Protein removal by alkaline protease digestion further reduced the PV, MV, and FV by 62, 19, and 78 RVU respectively. Brown flour showed a different pattern from the white flour. The presence of amino acids and beta-cyclodextrin inhibited the amylose-lipid complex formation, resulting in the reduction of the 2nd endothermic transition enthalpy. Beta-cyclodextrin reduced both the 1st and 2nd endothermic transition enthalpies. Addition of lipids increased the relative crystallinity and enhanced the V-type crystalline structure. The presence of beta-cyclodextrin enhanced the V-pattern of x-ray diffraction, whereas the addition of amino acids increased the 4.4 peak