Guucoamylase was immobilized by amidination reaction on the granular polyacrilonitrile resin which had been preliminarily treated with dry HCl in methanol. The granular polyacrilonitrile resin was made by drop-wise addition of the dimethylf ormamide solution of polyacrilonitrile to methanol. Continuous hydrolysis of soluble starch was operated in a column which was packed with the immobilized glucoamylase (granularity : 1 mmφ). Estimated values of apparent MICHAELIS constant (Km) with the immobilized glucoamylase depended on flow rates in the column and were found to be higher than that with the native glucoamylase in the batch system. The immobilized glucoamylase column was connected in a series with a column of the immobilized a-amylase (granularity : 30-200 μmφ). And, a soluble starch solution was firstly passed through the immobilized α-amylase column and then through the immobilized glucoamylase column. The effect of the pretreatment of soluble starch in the immobilized α-amylase column on the rate of hydrolysis was recognized with regard to the balance between amount of immobilized α-amylase and the degree of the hydrolysis in terms of reducing sugar unit. A similar effect was observed in the pretreatment of soluble starch with native α-amylase in a batch system. The molecular weight distribution of the reaction product of α-amylase processing was analyzed by the gel filtration (Sephadex G-75)method for the higher molecular weight fraction and by the thin layer chromatographic method for the lower molecular weight fraction up to DP 12. On the basis of these results, the pretreatment with α-amylase was thought to be significant particularly in that the effective concentration of the substrate was increased through the fission of the glucoside chains. The endurance test of the immobilized glucoamylase column was pursued by the continuous operation for two weeks with a flow rate of 0.5 ml/min at room temperature and 40°C. Similar situations were referred to in the previous study was obtained.

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Amylomaize starch irradiated with gamma rays up to 10 Mrad, was examined for the digestibility and compared with that of normal corn starch. 1) In the case of in vitro digestion with pancreatic a-amylase, the digestibility of both amylomaize and normal corn starches were elevated with increasing in radiation dose levels. Amylomaize starches irradiated at 0 and 10 Mrad were incubated with a-amylase for 24 hr and degraded 16.7% and 18.4%, respectively. Those of normal corn starches were 48.5% and 54.4%, as well. In the case of digestion with the extract of rat small intestine as degrading enzymes, the digestibility of 10 Mrad irradiated amylomaize and normal corn starches became slightly higher than those of the respective non-irradiated counterparts . 2) In vivo apparent digestibility of amylomaize and normal corn starches in growing rats showed a tendency to be lowered by the radiation, and a concomitant increase in weights of both feces and cecum contents was observed after feeding period of 28 days . From the results of in vivo observations, it seemed that both starches on the radiation received some structural modification, in which they could not be digested by the enzymes. However, amylomaize starch was less sensitive to this treatment than normal corn starch .

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Buckwheat flour starch was found to contain 2.24% of lipid, whose proportion for neutral lipid, glycolipid and phospholipid was 93:5:2. Free fatty acid was predominant among at least 9 kinds of neutral lipids. Seven species of glycolipid were detected, and acylsterylglycoside, sterylglycoside, monoglycosyldiglyceride, cerebroside and diglycosyldiglyceride were the main components. Among seven phospholipids phosphatidylethanolamine, lysophosphatidylcholine and phosphatidylcholine were predominant almost in a same rate. Lipids of buckwheat flour starch consisted of about 17 kinds of fatty acid as the constituent, and the main fatty acids were oleic, linoleic and palmitic in the decreasing order.

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[in Japanese]

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