Modification of starch in rice flours for frozen fried batter products

Rice and waxy rice flour were modified by hydrolyzed with alpha-amylase from Bacillus licheniformis at 77 unit/g dry weight flour with 200 ppm calcium ion, pH 6.9, at 50 deg C for 6 h. Enzyme activity was stopped by adjusting to pH 2 for 10 min. The starch was then cross-linked at 0.5 percent sodium trimetaphosphate for rice flour and at 0.1 percent for waxy rice flour, adjusting to pH 11, at 50 deg c for 1 h. The reaction was stopped by adjusting to pH 6.5, washed, filtered, and dried. Then the starch was pregelatinized by drum-drier at 40 lb/square in) steam pressure, 137 deg C, drum speed of 4.6 rpm, drum gap of 0.15 mm, grinded and dried to 9 percent moisture content. Rice flour mixed with modified rice starch at 80:20 and rice flour mixed with modified waxy rice starch at 90:10 were used for frozen fried batter product. Both mixtures exhibited properties of 34.67 and 34.84 percent amylose content, 77.18 and 76.88 deg C pasting temperature, 398.0 and 416.0 RVU hot paste viscosity, and 134.5 and 143.0 RVU breakdown value, respectively. Both mixtures were well disperse in water, viscous, dripless, well controlled pick up, gave light golden brown color, well adhered crust, medium oil absorption and high crispness product. Rice flour mixed with waxy rice starch gave light fragile crust which was the desired characteristics of the product. When frozen and reheated by deep fried, the product with both types of flour mixed had total descriptive score of 74.2 and 76.5 (from 100 score) and total hedonic score of 4.0 and 4.2 (5-point test) as compared to rice flour product with 50.0 and 2.3 score, respectively. It was found that when setback value of mixed flour increased the oil content in the reheated products were increased as well (r=0.726). When hot paste viscosity and breakdown value of mixed flour increased, the fracturibility of the reheated products were decreased (r=-0.733 and -0.813, respectively). When the products had lower chroma, oil content, and fracturibility, the panel found that the products exhibited less intense color, less oil absorption, and more crisp (r=0.674, 0.523, and -0.408, respectively).