Analysis of the characteristics and processing suitability of Hokkaido-grown rice flour

Three rice cultivars grown in Hokkaido were used to prepare 15 different types of rice flour by changing the combinations of mills and pretreatment conditions, and the proximate components of the rice cultivars and the characteristics of the rice flour were measured. Protein and amylose contents were found to vary with the rice cultivars. Rice flour characteristics, such as damaged starch content, mean particle size, and particle configuration, were determined to be influenced by milling conditions rather than by the rice cultivars. A high correlation was found between damaged starch content and mean particle size, water absorption capacity, and water penetration rate. The prepared rice flour was processed into sponge cakes, gluten-added rice flour bread, noodles using an extruder, and gel with a rice flour content of 12%, and the processed food items were tested to measure their characteristic values. These characteristic values of the processed foods and those of rice flour were analyzed, and it was revealed that the characteristic values of rice flour were highly correlated with four characteristics (i.e. damaged starch content, mean particle size, water absorption capacity, and water penetration rate) of the sponge cakes, three characteristics (i.e. damaged starch content, water absorption capacity, and water penetration rate) of the gluten-added rice flour bread, one characteristic (i.e. water absorption capacity) of the extruded noodles, and two characteristics (i.e. protein and amylose contents) of the gel with a rice flour content of 12%. The rice flour characteristics were found to be highly correlated with the characteristics of the processed food and which represented processing suitability. It was concluded that six rice flour characteristics above can be used as a quality indicator of rice flour.