Studies on the properties of some unutilized starch in Japan and Southeast Asia

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Molecular structures and the potential for industrial uses of three unutilized starches [water chestnut (fruits), yam(roots), and yam bean(roots)] were investigated in detail. In addition, the relationship between the structures and properties of starches from many plants, including the above, were analyzed.water chestnut amylose showed a characteristic wide molecular-weight distribution with 3 peak tops at d.p. 700, 1850, and 6670, and had a high -amylolysis limit of 95%. The crystalline type of the starch was C-type and the average chain length of the amylopection was 22, which is the intermediate value between A- and B-type starches.Yam bean starch granules showed also the C-type X-ray diffraction pattern and the number-average chain length of the amylopectin was 19.5. These amyloses were very large molecules whose molecular weights were distriduted in the range of 1500-300000d.p. (peak top at 10600 d.p.).Yam starches prepared from 3 varieties-- natives of Ibusuki Japan (KaU 18), Ja … More va (KaU 09), and Guam (KaU 14)-- showed similar physicochemical properties. The molecular weight distributions of amyloses were in the range of d.p. 300-18000 and the amyloses were relatively rich in small molecules which reduced the number-average d.p. of the amyloses. The number-average chain lengths of the amylopectins were about 2 units longer than that of potato amylopection.From the analytical data on various starches, it was found that the intrinsic viscosity of amylose is influenced by the amount of slighly branched molecules in addition to molecular weight. The intrinsic viscosities of 8 rice amyloses correlated well with the amounts of the slightly branched molecules but correlated poorly with molecular weights. The iodine affinities of amylopectins were found to be proportional with the amounts of super-long-chain chain components (d.p. about 1000).The slightly branched molecules found in purified amylose have been defined as an intermediate molecule by their molecular properties. Less