The degree of cross-linking of corn starch with epichlorohydrin (ECH) was investigated by determining the quantity of reacted ECH, which meant the starting quantity minus the unreacted one. Generally, on analytical technique of ECH, the following colorimetric determination has been used. The glycerol produced on hydrolysis of ECH by NaOH was oxidized to formaldehyde by sodium metaperiodate, which was detected by the reaction of chromotropic acid, and the quantity of formaldehyde was determined by absorbance at 570 nm by spectrometry. The special heat resistant vessel for ECH hydrolysis was prepared. The most suitable condition of hydrolysis was obtained through trial and error experiments. The degree of hydrolysis of ECH to glycerol was about 86%. Using the total organic carbon analyzer (TOC), the quantity of carbon of ECH in a solution was measured as the quantity of CO2 produced by complete combustion. The analytical results of both methods were well agreed, but it was considered that the spectrometry was complicated, time consuming and the narrower rang of determination compared with TOC method.

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Non-waxy rice starch was centrifuged (27, 300×g for 17 hr) in sucrose density gradient solution (10-40%) to divide into four fractions, Frs. 1-4 in increasing order of the rate of sedimentation. After dialysis to remove sucrose, structures of components of Frs. 1-4 were examined. Fraction 1, whose maximum wavelength (Amax) of the starch-iodine complex (625 nm) resembled that of amylose, bound to sucrose (36%) not to be removed by dialysis. Fraction 1 was debranched to result 85% of the long chain-length fractions (Fr. ‡T and Int. Fr.) and 14% of the medium chain-length fraction (Fr. ‡U). Fractions 2 and 3, whose Amax was similar to that of the mixture of amylose and amylopectin, had the optical densities of the absorption spectra little smaller than those of the mixture of amylose and amylopectin. Anomalous Frs. 2 and 3 were debranched to result 52% of the long chain-length fraction and 26% of the medium chain-length fraction and 21% of the short chain-length fraction. These results indicated that the structures of Frs. 2 and 3 were loosely branched. Fraction 4, whose λmax and β-amylolysis limit were similar to those of amylopectin, was debranched to result as same chain-length distribution as that of amylopectin. These results were similar to those obtained with the corn starches by the gel filtration. Fraction 4 was examined by the sucrose density gradient centrifugation (29, 300×g for 30 min, 1, 170×g for 30 min) to reveal that the molecular weights of the glucans were distributed in wide range, but the components of the upper and lower were not distinguished from each other with their properties.

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Starch samples were prepared from the roots of Shakuyaku, Paeonia lactiflora Pall. (Ranunculaceae); Hama-bofu, Glehnia lzfttoralis Fr. Schm. (Umbelliferae); corm of Saji-omodaka, Alisma plantago-aquatica Linn. var. orientale Samuels . (Alismataceae); bulb of Baimo, Fritillaria verticillata Willd . var. thunbergii Baker (Liliaceae); and rhizome of Oni-dokoro, Dioscorea tokoro Makino (Dioscoreaceae), by the yields of 9%, 8%, 14%, 22%, and 11% of the fresh tissues, respectively. These starches were examined on granular size and shape, X-ray diffraction pattern, iodine coloration, swelling power, solubility, amylogram, digestibility of raw starches by glucoamylase, etc. and the characteristic features of them were described. Both starches of Shakuyaku and Hama-bofu were swelled and dissolved partially at 60°Cin water, and their viscosity curves stood up slantways on amylograms . Starch granules from Baimo were large in size, contained high amounts of amylose, and hardly dissolved in boiling water. Oni-dokoro starch had very characteristic granuler shapes that are thin flat disks with notched edges.

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Effects of warm water treatment on gelatinization properties of air-classified potato starches (large, middle and small granular starches) were studied. By warm water treatment at 50.0 and 52.5°C for 1 hr, the properties of all three classified potato starches changed as follows. (1) The gelatinization temperature measured by photopastegraph, the pasting temperature and the temperature at maximum viscosity increased and the break down of amylograms decreased. (2) The swelling power and the solubility decreased. (3) The T30/T0 values evaluated from time-torque dependent curves decreased and dynamic modulus and viscosity of starch pastes increased. (4) Young's modulus and breaking strength of starch gels increased, but, strain ratio of them decreased. When treated with warm water, large granular starch showed slight decrease in maximum viscosity of amylogram, and small granular starch showed a more typical two-step swelling pattern in amylogram than large granular one. Judging from microphotographs under polarlised light and X-ray diffractograms, it was presumed that the changes in the gelatinization properties of the classified potato starches by the warm water treatment resulted mainly from structural changes in amorphous parts of starch granules.

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1. Effect of the addition of several divalent cations on the amylogram of milled rice flour was tested. The results coincided well with the known properties of cereal α-amylase, that is, the addition of Hg²⁺ and Cu²⁺ increased the viscosity of the paste, whereas Ca²⁺ decreased it. 2. Pretreatment of rice flour with 10-3M HgCI2 was sufficient to inactivate the endogenous α- amylase. 3. Effect of endogenous a-amylase on the amylogram of rice flour was more clear in glutinous rice varieties, suggesting the presence of higher amylase activity in these flours. 4. Results of the inhibition experiments using aged and unaged rice samples indicated that it is almost difficult to explain the difference between the amylograms of these flours by the levels of their endogenous a-amylase.

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