To investigate the physicochemical properties of Mochi, some were prepared using several preparative methods and with various additives. The texture of the Mochi was observed under a scanning electron microscope and the degree of gelatinization and some physical properties were measured. Mochi, prepared with a pounding type or stamping type machine, exhibited much of the initial rice grain structure, while, ones prepared with a mixer type machine were composed of a well smashed paste form rather than rice grain tissue. The changes in the degree of gelatinization during storage were determined using the β-amylase and pullulanase method, and only a slight decrease was observed. The physical properties of Mochi, prepared by the three methods, were measured using a rheolometer, a meatshear meter and an extensograph. Mochi prepared with the stamping type machine showed the greatest resistance to extension, and those prepared with the pounding type machine showed the greatest shearing strength. The ones prepared with the mixer type machine showed the minimum hardness and the lowest resistance to extension, and required the lowest shearing strength. The physical properties of three types of Mochi, made with 100% glutinous rice, 70% glutinous rice+30% waxycorn starch and 70% glutinous rice+30% cassava starch, respectively, were compared. The Mochi containing waxycorn starch were tender, and required a lower shearing strength, while those containing cassava starch showed increases in hardness and adhesiveness.

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To investigate the sensory attributes of “Mochi” with different additions, factor analysis of the results of sensory evaluation was conducted by the semantic differential (SD) method. Based on the profile of sensory attributes obtained with the SD method using 23 items concerning appearance, flavor, texture and preference image, it was found that two kinds of “Mochi, ” one made of 100% glutinous rice and the other made of 70% glutinous rice and 30% cassava starch, were relatively similar to each other except in appearance. Ones made of 70% glutinous rice and 30% waxycorn starch were characteristic in appearance, extension and softness. A significant correlation between the intensity and “like or dislike” of sensory attributes was observed for the “Mochi” in respect of items such as the following, which are more liked: “uniform tissue, ” “fine texture, ” “softness, ” “clearcut” and so on.
Through factor analysis (principal factor method) of the intensity of sensory attributes, the following three factors were extracted: the first was appearance, the second was preference image and flavor, and the third was texture. On factor analysis for “like or dislike” of sensory attributes, it was found that the first factor was texture and flavor, and the second was appearance. On testing of significance between paired samples for each factor, it was found that “Mochi” containing waxycorn starch were liked due to their appearance, while, ones containing cassava starch were liked for their texture and flavor.

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A commercial amylomaize starch, Amylon 50, was sub-fractionated with 1-butanol, and the two fractions (PF and SF) derived from the precipitate and supernatant fluid were characterized. The precipitated fraction (PF) was composed of amylose and amylomaize-specific amylopectin. An intermediate material was found in the supernatant fluid fraction (SF). Some characteristics of the intermediate material were consistent with those of a low-molecular-weight material previously isolated from amylomaize starch [T. BABA and Y. ARAI: Agric. Biol. Chem., 48, 1763-1775 (1984)]. The results of the present study, involving chromatographic separation with or without debranching treatment, demonstrate that Amylon 50 is composed of approximately 20% of amylose, 40% of amylomaize-specific amylopectin and 40% of the intermediate material.

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We applied the alkaline o-phenylenediamine (OPD) method to β-1, 3-linked glucans such as curdlan, scleroglucan and schizophyllan in alkaline media under heating and deoxygenated conditions. In the case of curdlan and laminari-oligosaccharide, (2′S, 3′R)-2-(2′, 3′, 4′-trihydroxybutyl) quinoxaline (G-1) was formed from the glucose residues in the main-chain, and several quinoxaline derivatives including G-1 from the non-reducing end groups. In the case of scleroglucan, G-1 was formed from β-1, 3 linked sugar residues in the main-chain, and a quinoxaline, designated as QD-I, from the branching disaccharide units. The scleroglucan tested had a branch at intervals of every 2.3-2.6 glucose units along the main-chain residue.

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Potato amylose (Amylose V) was partially hydrolyzed with β-amylase, and the iodine binding capacities of the partial hydrolyzates and β-limit dextrin were compared with that of the original amylose. The iodine binding capacity did not change until approximately 30% β-amylolysis, and then gradually decreased up to the β-amylolysis limit. The reduction was directly proportional to the degree of β-amylolysis. The iodine binding capacity of the β-limit dextrin was 11.7% lower than that of the original potato amylose.

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The components of Amylon 70 starch were examined quantitatively. The Amylon 70 contained approximately 25% of amylose and 20% of amylomaize-specific amylopectin. The amount of the major component, with a lower molecular weight than that of amylose, was estimated to be almost 55%. Some properties of the low-molecular-weight material were consistent with those of the intermediate material from the other amylomaize starches described previously.

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The size and the shape of shellfish glycogen particles varied with the extraction procedure. Glycogen particles prepared by the dimethyl sulfoxide (DMSO) extraction method were relatively large in size and showed a rosette-like structure (large particle, α-particle) composed of several small particles (β-particle), whereas glycogen extracted with trichloroacetic acid (TCA) and commercial glycogen prepared by extraction with barium hydroxide containing zinc sulfate showed much smaller particle size. The latter preparations did not have a rosette-like structure and they were more susceptible to pullulanase. Treatment with acids, such as TCA and phosphotungstic acid, reduced the size of particles significantly but, on the other hand, the particles were rather resistant to alkalis, such as 0.1M or 0.5M sodium hydroxide. The large particles were not dissociated into small particles on treatment with 2-mercaptoethanol, or on protease or β-amylase treatment. Short time exposure of the large particles to a high concentration of α-amylase caused some degradation, yielding small particles. These results suggest that each large glycogen particle is composed of several small particles, which are linked to each other through an α-1, 4-glucan chain.
There are two forms of glycogen phosphorylase in oyster adductor muscle, namely, an AMP-independent form (phosphorylase a) and an AMP-dependent form (phosphorylase b). Purified phosphorylase a was not inhibited by ATP or glucose-6-P in the presence of AMP, while phosphorylase b was strongly inhibited by ATP and glucose-6-P. Unlike in the case of mammalian phosphorylases, it was shown that in the oyster adductor muscle, phosphorylase b was regulated by the concentrations of glucose-6-P and ATP, and the rate of conversion from the b form to the a form was very low. Only the AMP-dependent form (phosphorylase b) was found in scallop adductor muscle. The purified phosphorylase b from the scallop adductor muscle showed strong affinity to AMP (Km for AMP, 17.4μM). It was shown that in the scallop adductor muscle, the activation of the phosphorylase was not caused by conversion from the b form to the a form, but by the increase in AMP concentration.

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The actions of amylases in the vicinity of the phosphate groups at C-3 and C-6 of the glucosyl residues of potato starch and the locations of the phosphate groups in the starch, which were determined by analyses of the phosphorylated products, were summarized.
Sweet potato β-amylase and Aspergillus niger glucoamylase cleaved the (1→4)-α-D-linkage of the 6-phosphorylated residue at the non-reducing side but not that of the 3-phosphorylated one, leaving at least one glucosyl residue attached to the 3-phosphorylated one. α-Amylases from various origins cleaved different sites in the vicinity of the 3- and 6-phosphorylated residues, that is, the enzymes from Bacillus subtilis, porcine pancreas and Aspergillus oryzae produced 3²-phosphoryl maltotetraose (3²-PG₄) and 6²-phosphoryl maltotriose (6²-PG₃), 3²-PG₄ and 6³-phosphoryl maltotriose (6³-PG₃), and 3²-PG₄ and 6³-PG₃, respectively, upon exhaustive hydrolysis. The phosphate group at C-6 was as obstructive as the branch linkage of amylopectin, but less obstructive than the phosphate group at C-3. Their inhibitory behavior seemed to reflect a bulk rather than an electronegative effect.
Most phosphate groups were found in the amylopectin fraction. The results of analyses of phosphorylatedbranched- and unbranched-chains produced from potato amylopectin on exhaustive β-amylolysis followed by isoamylolysis indicated that the phosphate groups were located mostly in B-chains (chains with side chains) and largely on the outer section of chains of amylopectin, except in the vicinity of the branch linkages.

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