Abstract
Japonica rice is currently used to manufacture breads and cakes, and there have been many studies of the texture and taste of these items, but the preparation and practical use of rice noodles, which are manufactured using a rolling process, have not yet become viable because rice does not contain gluten. Following preparation of Vietnamese rice noodles made from Indica rice, we established in a preliminary experiment a method of obtaining noodles of consistent quality by cooking at 65°C. We prepared Japonica rice noodles with addition of tapioca starch and soy milk in order to improve their texture and nutritional value, and we conducted mechanical measurements using a Rheoner and sensory evaluation tests. The flow behavior of the rice flour suspension was measured by viscometer. Enthalpies of gelatinization and changes of state for Indica and Japonica rice starch were measured by DSC and followed by optical microscope observation during heating. These measurements showed that Japonica sol had high viscosity and high thixotropy at 90°C. The thixotropy was decreased by addition of tapioca starch but increased by the addition of soy milk. An increase in Casson yield stress was also confirmed in all cases. Based on the properties examined by DSC and optical microscope observation, the gelatinization temperature of Japonica rice was around 60°C, which was lower than that of Indica rice by about 10°C. Although the cooked noodle made from Japonica rice was soft and sticky and received unfavorable evaluations, noodles with added tapioca starch and soy milk received favorable evaluations.
