Effect of drying on physicochemical properties of noodles made from Parboiled Hom-Nin brown rice flour with mixed rice flour

Abstract

This research is aimed at studying the effect of noodle drying from parboiled Hom-Nin brown rice flour with mixed rice flour to change of physicochemical properties. Parboiled Hom-Nin brown rice flour was produced by soaking Hom-Nin brown rice at 40±2°C for 4 hr, steaming at 100°C for 15 min and drying. After that, the flour is produced by wet milling and freeze drying. Flour products were used to produce fresh noodles and dried noodles at temperatures of 50, 60 and 70°C. The initial moisture content was 60-63%wb and dried until final moisture content was 12-13%wb. It was found that the decrease of moisture in drying time was not linear correlated with drying time. At high drying temperatures (70°C), the maximum drying rate was 2.307 kg/hr and decreased to 0.965 kg/hr and 1.399 kg/hr at 50 and 60°C, respectively. The testing physical and chemical changes, it was found that anthocyanins content from Hom-Nin brown rice (9.51 mg/g dry weight) tendency decreases after drying period (0.02-0.04 mg/g dry weight). However, it is still higher than rice noodles from rice milled. Corresponding to the change in color values, lightness value (L*) redness value (a*) decreased as the drying temperature increased while the yellowness value (b*) is higher. After drying, the final moisture content of the noodles was about 13%wb. And water activity value was lower than 0.6 which is at a reasonable level of storage. When testing the total microbial value, the values between 1.8×102 - 6.8×102 CFU/g are safe for consumption. Including, testing the tensile strength, it was found that noodles produced from parboiled Hom-Nin brown rice flour with mixed rice flour have a soft sticky especially noodles are dried at 50°C.