Deagglomeration of rice starch-protein aggregates by high-pressure homogenization

Starch-protein agglomerates of rice are physically disrupted in presence of water by use of a high pressure homogenizer called microfluidizer(R) followed by density based separation. Rice flour slurry at concentrations of 22, 32 and 36 0% 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 mum, 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 degreesC for waxy and 81.33 degreesC 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.