The effect of Alkalis on rice starch granule during the alkaline purification of rice starch was studied. By the first treatment of rice powder by diluted aqueous alkaline solution for 3 hrs., 98% of protein, 90% of lipid, 85% of ash in polished rice powder were dissolved and removed by washing. The starch granules prepared by higher temperature and increased washing with alkaline solution had tendencies to increase viscosity rapidly after gelatinization compared with slow increase of viscosity of the ones prepared at lower temperature and lesser alkaline washing. According to our studies, it became clear that less modified rice starch was prepared by one alkaline soaking with stirring for 3 hrs, and followed with water washing. This modified method to use fine rice powder through 100 mesh enabled to shorten the period of rice starch preparation.
The utilization of dried powder of sweet potato, which was prepared after the removal of soluble components-a very useful medium for microbes, was investigated for the purpose of complete utilization of sweet potato. 1. The above dried powder was found to be available to a material for alcohol fermentation. 2. The yield of starch from the dried powder increased through the adequate alkali treatment (pH 9.5-11.0), to attain to almost the same yield as that in the usual method from the fresh sweet potato. 3. The quality of the above prepared starch such as in x-ray diffraction and amylography was not so much different from that of control except the slightly higher content of protein and the lower degree in whiteness. Dehydration of sweet potato became four times more rapid by removing the soluble components, and the dried powder could be used to prepare starch even after a year of storage as much as soon after drying. Therefore, if some device is done for the starch to be higher in whiteness, a new process for manufacturing starch from sweet potato might be expected to be designed.
A new flow diagram to determine carbohydrase activities by modified f erricyanide method with Technicon autoanalyzer was proposed. Using reduced short chain amylose of OP. 20 as a substrate, activity of the maltohexaose producing amylase, which is a newly discovered exo-amylase from Aerobacter aerogenes in this laboratory, was determined exclusively in the presence of pullulanase or other debranching amylases. This system has high sensitivity to determine the level of 0.01 I.U./ml of the enzyme activity and also can determine 20-30 enzyme samples per hour. Also, this procedure is applicable for the determination of the elution profile of column chromatography of amylases, pH-dependence, effects of metal ions on enzyme activity and stability of enzymes etc. Several examples of the determination are shown in the text.
In 1964 Mertz et al. reported that opaque-2 (O2) gene changed the protein composition and increased the lysine content of maize endosperm. A second high lysine maize mutant floury-2 (fl2) was identified and reported in 1965. Recently, it was found that several of starch-modifying genes increased the lysine content of maize endosperm substantially above the isogenic normal control, and each gene showed an enhanced effect on lysine when combined with O2 gene. Mutants with starch-modifying genes were concerned with changes influencing gelatinization temperature, viscosity, gel stability of starch, starch granule digestibility, and the production of amylose, amylopectin, water-soluble polysaccharides, and sugars. In studies of starch-modifying genes and their combination with O2 or fl2 gene, it was shown that O2 or fl2 dose not change the production of amylose, amylopectin, water-soluble polysaccharides, and sugars of maize kernels with each one of starch-modifying gene, and O2 gene has no effect on susceptibility of starches with amylases. It seems probable that the interaction of the O2 gene with many of starch mutants of the maize endosperm provide a variety of maize containing starch with characteristics specific for the starch mutant and protein with high nutritional quality.
A questionnaire concerning the prospect for amylase industry has been sent to the person who engages in either industrial production or utilization of amylase in this country . Out of 70 discharged, 51 have been recovered. Forms of the questionnaire are shown in Table 2 and 3, filled with the numbers of total marks answered in the returned forms . It is noticed that the utilizations of amylase in fermentation industries, as well as in the productions of maltose and of modified starch, are expected to increase in near future . The following problems are regarded as to be solved for further development of the amylase industry: Raw starch digestable amylase, immobilized amylase, extremely thermostable amylase, higher oligosaccharide producing amylase. New sources for currently utilizing types of amylase are not much demanded presently.