DEVELOPMENT OF ADVANCED PHYSICAL MEASUREM ENT METHOD FOR INDIVIDUAL COOKED RICE .1. MANY-SIDED EVALUATION OF PHYSICAL-PROPERTIES OF COOKED RICE GRAINS WITH A SINGLE APPARATUS

Multiple physical tests using a compression tester (Tensipresser) were performed to realize many-sided quantification of physical properties of individual cooked rice and to develop an objective method for meas uring texture of cooked rice grains. It was considered that compressio n ratio in low compression tests (small deformation) was appropriate t o be set for minimum 25% for detecting narrow difference between varie ties in both hardness and stickiness on the outer layer of cooked rice grains. In compression tests, the repeatability in high compression t est (90% deformation) was better than that in low compression tests (1 5%, 25% and 35% deformation). And also the repeatability of stickiness (-H-1) was worse than that of hardness (H-1) in each compression test . It was possible to evaluate physical properties of the outer layer a nd the overall of cooked rice grain and to distinguish subtle differen ce in varieties by combined evaluation with two compression tests (25% -low and 90%-high). With respect to continuous progressive compression lest (CPC test) based on the new principle or detecting compression f orce and reverse force continuously when cooked rice grain was compres sed progressively at the continuous amplitude of vibration, elastic li mit length (ELL) showed low coefficient of variance comparatively and was able to display the feature of each variety. We concluded that har dness and ratio of elastic limit length (RELL) by two tests (25%-low c ompression test and CFC test), introduced newly, can differentiate the feature of each variety well and the combination of these tests is ap propriate as an objective method of cooked rice texture.