2022 Volume 91 Issue 2 Pages 136-146
Low amylose rice exhibits strong stickiness and is still soft even after cooling. However, its low yield and lower molding efficiency because of the stickiness of the cooked rice during processing remained as problems. Here, we examined the effect of nitrogen application on the yield and eating quality of the low amylose rice cultivar, Kiraho, which was developed in Iwate Prefecture. The number of husks and the yield increased with the increase in the amount of nitrogen used for topdressing the crop. Regarding the texture of cooked rice, there was a positive correlation between the polished rice protein content (PPC) and the surface hardness of the cooked rice, and a negative correlation between the PPC and the surface adherence of the cooked rice. The increase in PPC after increasing the nitrogen for topdressing was suggested to reduce the stickiness of the cooked rice, an important factor during the molding process. However, there was no significant difference in the whole grain hardness of the cooked rice between different treatments of nitrogen topdressing, with the sensory evaluation showing only a small decrease in the overall eating quality. These results suggest that increase in the amount of nitrogen topdressing for the Kiraho cultivar improved its yield, modified the physical properties of the surface layer of the cooked rice by increasing the protein content and reduced the stickiness during processing, while hardly affecting the eating quality.
