A high-amylose (>30%) rice is inferior to a low-amylose rice for the raw material of processed-rice products. To elucidate the cause, we investigated properties of the rice starch pastes sampled at various stages of gelatinization during amylography using the rice starch with amylose content of 31.0% from Hokuriku 142 and the rice starch with amylose content of 19.0% from Koshihikari. The rice starch pastes used for analysis were freeze-dried and pulverized with a coffee mill. The rice starch with amylose content of 31.0% showed lower peak viscosity, less break down and higher final viscosity than the rice starch with amylose content of 19.0% upon the amylogram. The degree of gelatinization by enzymatic method, swelling power and the acid-solubility by 0.25 N HCl solution (at 55°C, for 2 hr) were low for the freeze-dried rice starch pastes with amylose content of 31.0%, and high for the freeze-dried rice starch pastes with amylose content of 19.0%, respectively. The acid-solubility showed more the difference between them than the degree of gelatinization by enzymatic method, and swelling power. From these results, it could be supposed that to be inferior to processing suitability for high amylose rice is caused by giving low degree of gelatinization. And it may well be that the acid-solubility is available to assess the property of the rice starch on the rice processing.

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Taro (Colocasia esculenta (L.) Schott, cultivar : Ono-zairai) was cultivated in lysimeters which are equipped in glass house, and was grown under a different condition of soil moisture by changing the ground-water level. Amylose content of taro starch did not change under the different ground-water level. However, both the ratio of short chain to long chain of amylopectin and the heat of gelatiniza tion of starch granules were increased under the lower level of ground water. It was suggested that the structure of taro starch was affected by the soil moisture condition.

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Taro (Colocasia esculenta (L.) Schott, cultivar : Ono-zairai) was grown under the different soil series groups in Katsuyama. The properties of starch prepared from the secondary tubers were examined. Both amylose content and gelatinization characteristics of starch-granules scarcely changed among soil series groups. However, the ratio of short chain to long chain of amylopectin was distinctly different from soil series groups, and increased at gravelly gray lowland soil. On X-ray diff ractometry, all starch-granules showed A-type pattern.

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Structural characteristics of rice endosperm starches were studied. Sample seeds were from thirty-three varieties of rice including twenty-nine new varieties of rice grains harvested in 1990 and 1991. The amylose content of the starch samples varied from 8% to 31%. The amylose content (y) measured by debranching α-1, 6 glucosidic bonds of starch followed by gel permeation chromatography and blue values (x), optical density at 680 nm of starch-iodine complex absorption curves, had a linear proportional relation and followed the regression equations y=99.1 x-5, 0. The starch granules which had higher amylose content were more resistant to amylolysis. The cultivars whose cooked rice had a higher taste score by organoleptic test tended to contain less amylose in their endosperm starches.

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Gelatinization properties of rice endosperm starches extracted from thirty-three varieties of rice including twenty-nine of new types of rice grains were characterized by differential scanfling calorimetry and by measuring swelling power and solubility of starch. The starches which had higher content of amylose showed lower temperature and smaller heat content of gelatinization, lower swelling power and higher solubility at 85°C. The gelatinization properties such as heat of gelatinization and swelling power at 85°C were significantly related to taste score by organoleptic test of cooked rice. Slurry of 10% of milled rice flour was also charac terized by a viscometer. Setback values, which is the recovery of the viscosity by cooling after heating the slurry, had a positive correlation with amylose content of endosperm starches.

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The relationship between the molecular structure of amylose and the texture of cooked rice was investigated using Korean rices (3 varieties of japonica type and 3 varieties of tongil type (japonica-indica breeding type)). The inherent viscosity and number-average degree of polymerization of japonica type amylose were lower than those of tongil type amylose. The fraction of molecular weight above 5 × 10⁵ for japonica type amylose was 31.7-37.1% and that for tongil type amylose was 43.8-47.5%, indicating that molecular size of japonica type amylose was smaller than that of tongil type amylose. The content of hot-water soluble amylose and ratio of hot-water soluble amylose to total amylose of japonica type were higher than those of tongil type amylose. With the texture of cooked rice, japonica type had low hardness, high adhesiveness and high ratio of adhesiveness to hardness compared with tongil type. The inherent viscosity, number-average degree of polymerization and molecular weight size of amylose showed a positive correlation with hardness, but a negative correlation with adhesiveness of cooked rice. The results suggest that the molecular structure of rice amylose could be at least partly responsible for the texture of cooked rice.

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Bracken (Pteris aquilinum L.) rhizome starch is manufactured in Kagoshima for limited uses. The bracken starch granules were small (average diameter 10-13μm) and gave a Cc-type X-ray diffractogram. The starch contained 19.7% amylose based on the iodine affinities of starch, amylose, and amylopectin. It contained 72 ppm of organic phosphorus mostly in the amylopectin molecule (90 ppm). The amylose molecules are rather small compared with starches of other underground organs having dj p. n 1990. d. p. w 3800 and the apparent d. p. distribution range of 670-8500. The c. 1. n of amylopectin was 21.5. Gelatinization temperature was 59.5°C by photopastegraphy. The maximum viscosity measured by a rapid visco analyzer (RVA) was 104 and 413 SNU at 6 and 10%, respectively, similar values to those of tapioca, sweet potato and arrowhead starches, but higher than those of kuzu and corn starches. The pasting behavior by an RVA was roughly between those of maize and potato. The retrogradation tendency of the starch was a little less than that of kuzu (Pueraria hirsuta Matsum) starch.

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I am highly honored and pleased to receive the Award of Merit of the Japanese Society of Starch Science (JSSS). My connection with Japan and starch began when I was a graduate research assistant in the laboratories of Professor Roy L. Whistler at Purdue University. In the early 1960's, Professor Jiro Nikuni visited Professor Whistler's laboratory several times, and their common interest and love of starch science captivated many others. Within those same years, Professor Hidetsugu Fuwa returned to Purdue as a research associate in the laboratories of Professor Bernard Axelrod. In 1983, I visited Dr. Keiji Kainuma at Tsukuba City, and with his encouragement, I began to attend the meetings of the JSSS. Since then, I have returned to Japan often, where I have come to know and admire the qualities of its people, including talent, hospitality, discipline, allegiance, diligence, frugality, harmony, and love of solitude. I thank the members of the Society; my nominator; the Selection Committee; and the President of the Society, Professor Susumu Hizukuri, for this great honor.

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The physicochemical properties of starches from 72 kinds of Japanese wild plants have been characterized. To simplify the characterization, four terms of properties were selected, namely, average granular size, apparent amylose content, and the maximum viscosity and the gelatinization temperature of Brabender amylogram, and analyzed statistically on their correlations. The four terms were arranged in cross-shaped graphics to visualize characters of starches. Based on the graphs the characters of the starches were discussed from the aspects of their storage organs (tissues), botanical classifications, etc.

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