Deagglomeration of Rice Starch-Protein Aggregates by High-Pressure Homogenization

Abstract

Starch-protein agglomerates of rice are physically disrupted in presence of water by use of a high pressure homogenizer called microfluidizer® followed by density based separation. Rice flour slurry at concentrations of 22, 32 and 36 % was passed twice through the microfluidizer to determine optimum concentration and recycling conditions. It was determined that 32 % slurry and two passes were optimum but the optimum pressure was 10.0 x 10 4 kPa for non-waxy rice flour and 6.2 x 10 4 kPa for waxy flour. These conditions yielded low-protein starch with starch damage of 5.3%, 99.9% particles with size less than 10 μm, starch recovery of 72% and 2.7% protein in starch for non-waxy starch. The same parameters were 6.1%, 99.0%, 76% and 3.3% for waxy starch. The peak, minimum, breakdown, final and setback viscosity was 237.8, 115.2, 122.6, 145.1, 29.9 and 68.2 RVU for low-protein waxy rice starch and 223.4, 140.2, 83.2, 258.6 and 118.4 RVU for non-waxy low-protein rice starch, respectively. The pasting temperature was 68.7 °C for waxy and 81.33 °C for non-waxy low-protein rice starch. The solubility of protein increased with increasing concentration and number of passes, however, it decreased with increasing number of passes for waxy rice protein.