豆類の吸水特性

Characteristics of water absorption of soybean, azuki bean and kidney beans (cv. Toramame and Taishokintoki) were investigated. The way of water absorption of soybean was different from that of other beans, because soybeans absorbed water from whole surface of seed coat immediately after the immersion. Azuki beans absorbed extremely slowly water from only strophiole, and then the water absorption in other tissue was induced by a certain amount of water absorption playing a role of trigger. Therefore, the rate of water absorption of azuki bean increased since the changing time. The rate of water absorption of Toramame and Taishokintoki was intermediate between those of soybean and azuki. It was assumed that micropyle in those kidney beans plays a important role in water absoption

豆類の脱湿・吸湿時における挙動について

The changes in water contents of adzuki beans, cowpeas, toramames (a variety of kidney bean) and soybeans during removal and absorption of moisture were investigated to clarify the effect of humidity on behavior of beans. It was found that dehumidified adzuki beans hardly absorbed moisture even if they were put in the overhumid circumstance for a long time and the dehumidification of adzuki beans occurred through hilum. Beans other than adzuki beans absorbed more moisture than the original water content by addition of moisture after dehumidification. Adzuki beans were used as the stuff for packing into pillow in Japan till recent years. This suggests that the characteristics on dehumidification and humidification of adzuki beans were utilized for the material

Characterization of pullulanase (PUL)-deficient mutants of rice (Oryza sativa L.) and the function of PUL on starch biosynthesis in the developing rice endosperm

Rice (Oryza sativa) allelic sugary1 (sug1) mutants defective in isoamylase 1 (ISA1) accumulate varying levels of starch and phytoglycogen in their endosperm, and the activity of a pullulanase-type of a debranching enzyme (PUL) was found to correlate closely with the severity of the sug1 phenotype. Thus, three PUL-deficient mutants were generated to investigate the function of PUL in starch biosynthesis. The reduction of PUL activity had no pleiotropic effects on the other enzymes involved in starch biosynthesis. The short chains (DP ≤13) of amylopectin in PUL mutants were increased compared with that of the wild type, but the extent of the changes was much smaller than that of sug1 mutants. The α-glucan composition [amylose, amylopectin, water-soluble polysaccharide (WSP)] and the structure of the starch components (amylose and amylopectin) of the PUL mutants were essentially the same, although the average chain length of the B2-3 chains of amylopectin in the PUL mutant was ∼3 residues longer than that of the wild type. The double mutants between the PUL-null and mild sug1 mutants still retained starch in the outer layer of endosperm tissue, while the amounts of WSP and short chains (DP ≤7) of amylopectin were higher than those of the sug1 mutant; this indicates that the PUL function partially overlaps with that of ISA1 and its deficiency has a much smaller effect on the synthesis of amylopectin than ISA1 deficiency and the variation of the sug1 phenotype is not significantly dependent on the PUL activities