The gelatinization characteristics of heat-moisture treated potato and corn starches were investigated using five different methods, namely, swelling-power solubility measurement, photopastegraphy, Brabender-viscography, differential scanning calorimetry (DSC) and dynamic viscoelasticity measurement. 1) Compared with the native starch, swelling-power and solubility of each heat-moisture treated starch was considerably suppressed. 2) The gelatinization temperature of each heat-moisture treated starch, measured using different experimental instruments, was higher than that of the corresponding native starch. 3) Both the native potato and corn starches showed an increased transmittance in the photopastegrams with an increase in temperature, whereas there was a decreased transmittance of the heat-moisture treated starches. 4) Viscograms of both heat-moisture treated starches indicated considerably suppressed maximum viscosity and no breakdown. 5) DSC curves show two endothermic peaks in the low and high temperature regions for heat-moisture treated potato starch and one peak for the native potato starch. Both DSC curves of the native and heat-moisture treated corn starches showed two peaks. 6) The curves of storage modulus (G') and loss modulus (G") for the heat-moisture treated potato and corn starches during gelatinization showed higher stability at high temperature compared with the native starches. The heat-moisture treated corn starches showed a small difference between G' and G" in the high temperature region, and a larger value for tan δ than that of the corresponding native starch.

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The concentration dependence of mechanical properties of native and heat-moisture treated (HMT) corn, cassava and potato starches near the sol-gel transition point was analyzed by the scaling law derived from the percolation theory. Since the storage modulus (G′) curves for a starch slowly decrease with decreasing frequency, the plateau region at a frequency of 10^-1 s^-1 is shown to represent the elastic modulus that characterizes the network structure. The gelatinized concentration of HMT corn starch increased more than that of the native type, with the starch gels being observed to decrease in firmness with HMT. The gelatinized concentration of HMT cassava starch also increased more than that of the native type, while the storage modulus increased more than that of 4 wt% native cassava starch, being soft at a low concentration, and firm at higher concentrations. The gelatinized concentration of HMT potato starch also increased more than the native type, but was softer than the native type. The scaling law could not be applied to the native and HMT potato starches, although the critical exponents were determined as 4.2 and 3.6 for the native and HMT corn starches, and as 1.8 and 2.4 for the native and HMT cassava starches, respectively.

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Among twenty six thermophilic strains of actinomycetes investigated, Streptomyces thermocyaneoviolaceus IFO 14271 showed the highest raw starch-digesting amylase activity. The enzyme was purified to homogeneity by ammonium sulfate precipitation, raw corn starch-Hyflo Super-Cel affinity chromatography and FPLC MONO Q 5/5. The purified enzyme gave a single protein band on SDSPAGE. The molecular weight of the enzyme was estimated to be 49, 000 by SDS-PAGE and 47, 000 by TOF-MS. The optimal temperature and pH were 40°C and 6.5, respectively. The enzyme lost 65% of its activity on preincubation with EDTA which was partly restored by incubation with Ca²⁺ . The enzyme effectively digested raw starch granules from wheat, waxy corn, rice, corn, sweet potato, tapioca, sago and potato, forming maltose as the major end product. The enzyme was determined to be a-amylase.

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A δ-Fructofuranosidase from Arthrobacter sp. No. 18-2 was purified into a homogeneous state. The molecular weight of the enzyme was estimated to be 26, 500 by sodium dodecyl sulf ate-polyacrylamide gel electrophoresis (SDS-PAGE). The p1 of the enzyme was 5.8. The optimum pH and temperature were pH 6.0 and 50°C. The enzyme was stable between pH 5.5 and pH 10.5 at 4°C for 20 h of incubation, and below 30°C for 15 min of incubation. The enzyme could hydrolyze not only low molecular weight substances such as sucrose, 1-kestose, nystose and levan-oligosaccharides, but also high molecular weight fructans, levan and inulin, which were hydrolyzed to liberate only D-fructose. The reactivity (Vmax/Km) of the enzyme with sucrose was 252 times greater than that with levan, and 60 times greater than that with inulin; the enzyme was classified as δ-fructofuranosidase. The degree of decrease in reactivity associated with substrates of increasing molecular weight was not so steep compared with other δ-fructofuranosidases. The enzyme could hydrolyze both δ-2, 1- and δ-2, 6-fructosyl linkages in low and high molecular weight compounds, and was characterized as having a relatively wide substrate specificity.

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The effects of calcium gluconate (GCA) supplemented with calcium stearoyl-2-lactylate (CSL) or sodium stearoyl-2-lactylate (SSL) on some rheological properties of wheat flour dough, and on loaf volume were studied. Additions of CSL with and without GCA increased the loaf volume by 0.3-0.5% (on flour volume basis) compared with that of the control. However, combined additions of CSL and GCA did not have any synergistic effects on the loaf volume. Combinations of SSL (0.5%) and GCA (0.3%) increased the loaf volume compared with SSL alone. Mean diameters of gas cells of baked bread crumbs containing either SSL or SSL+GCA were slightly larger than those of CSL or CSL+ GCA. Combinations of SSL and GCA improved rheological properties of dough such as dough stability, stress and modulus of elasticity when compared with the single addition of SSL only. Results showed that stearoyl-2-lactylate, especially its sodium form and its combination with GCA, improved rheological and baking properties of dough when combined with the cooperative actions of gluten and starch.

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The relations between properties of commercial sweetpotato starches (warabi-mochi flour) and particle-size distribution, mineral composition, and defatting of the starches were investigated. The results were as follows. 1) Mineral composition and limewater treatment had no effect on the pasting properties and texture of the starch gels. 2) Classified starch samples having a larger particle-size distribution showed larger breakdown and smaller setback in pasting properties, and also less firmness in their gel texture than those starch samples having a smaller particle-size distribution. 3) After defatting, the decrease in the initiation temperature of breakdown and in the ratio of setback for pasting properties was observed. Firmness of the starch gels decreased but their cohesiveness increased by defatting. These observations showed that particle-size distribution and defatting largely affect pasting properties and gel texture as a result of change in resistibility to degradation of the starch granule.

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Sixty-six starches from wild plants in Japan were classified into five groups by various methods, including by cluster analysis and by characterization of groups visualized by radar chart, scaled with the Z-score (the normalized deviation). 1) The seeds' starches (22 species) and A⋅C diffraction-pattern starches (35 species) had negative Z-scores for all properties as well as a smaller circle-shaped radar chart, whereas the B-pattern starches (31 species) showed a larger circle. Monocotyledon (34 species) and dicotyledon (26 species) starches differed in the Z-scores for gelatinization properties. 2) Cluster analysis was done for the classification of starches, using commercial starches (corn, sweet-potato and potato starches) as the standards. The starches were able to be classified into five groups based on the dendrogram obtained; corn type (20 species), sweetpotato type (24 species), potato type (13 species), high-amylose type (3 species), and low-amylose type (6 species). The corn type of starches, including most Graminales seed starches, showed mainly the A pattern, negative Z-scores for all properties, and a small circle-shaped radar chart. The sweetpotato type, including most tree nut starches, had an medium-sized circle-shaped radar chart, representing a mean Z-score value. The potato type, mainly from Scitamineae roots, showed the B pattern, and a large circle-shaped radar chart. The last two groups classified were the high-amylose type, including hoshida (Thelypteris acuminata MORTON), and low-amylose type, including kuwazuimo (Alocasia macrorrhiza ScoTT), these groups were characterized by asymmetric and distorted circles in their radar chart. 3) By plotting the mean granule size against the maximum viscosity we were able to distinguish and rationalize the difference between these five types of starches. Starches belonging to the corn, sweetpotato and potato types were most common, and were arrayed on the regression line between the maximum viscosity and the granule size. On the other hand, high-amylose type and low-amylose type starches were disproportionally along the X-axis and Y-axis, respectively, thus indicating that they were uncommon starches according to the "starch measure" concept.

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Previously, we observed the inhibitory effect of potato-starch derived phosphorylated oligosaccharides (PO) on the formation of calcium phosphate precipitate. In the present study, we investigated the digestibility of PO by rat intestinal acetone powder, in addition to the utilization of calcium by rats in the presence of PO. PO was only partly digested (30%) by intestinal acetone powder, whereas sucrose and maltose were completely digested. The small intestine of rats was ligated in situ and the degree of calcium absorption in intestines after injection of 10% PO containing 57 mM calcium chloride was measured. PO had a greater effect on calcium absorption than sucrose. The effect of PO-feeding on calcium utilization in rats was also examined. The apparent calcium absorption ratio and the apparent retention ratio were slightly higher in rats fed PO than those in the control, although no statistical significant differences were observed between the treated and control rats. Results of the tests on breaking-force and calcium-content of the femurs were similar to the calcium-absorption test results. In order to clarify the promotion of utilization of calcium by PO, further studies are needed.

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The changes of dynamic viscoelastic properties of 10% rice starch suspension during heating at rate of 1°C/min was measured while ensuring the linearity between stress and strain and avoiding the sedimentation of starch. The temperature dependence of the dynamic modulus for rice starch during gelatinization can be expressed by a gelation and fusion profile which correspond to five stages: I, expanding the volume fraction; II, filling between particles; III, diffusion of water into the crystalline region; IV, fusion process of the crystalline region; and V, development of mechanical strength.

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Cycloamylose glucanotransferase (CGT, EC 2.4.1.19) from Bacillus stearothermophilus was confirmed to catalyse the reaction for a substrate, maltose. When this reaction was carried out in the presence of isomaltose, a trisaccharide (X3) was primarily produced. Based on glucoamylase digestion and NMR analysis, X3 was concluded to be isopanose. The reaction is probably one of the most useful techniques for the production of Isopanose. In the presence of cellobiose/lactose, the CGT reaction for maltose was found to result in new products trisaccharide and tetrasaccharide having α- and δ-glycosidic linkages. This reaction system will be used to produce some oligo-sugarchains ("tousa").

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In this paper, we report the discovery of a relatively low-amylose sweetpotato starch. The chain-length distributions of debranched starches from 29 kinds of breeding lines of sweetpotato used in soups, croquettes and juices were examined. Among the 29 varieties, the starch from Kyukei 89376-12 had the smallest amylose fraction (11.7%), which was half that (21.6%) of a commercial sweetpotato starch. The apparent amylose content of the sweetpotato starch was estimated to be 11.3% and 10.9 by the blue-value method and the dual-wavelength method, respectively. The low-amylose starch showed relatively high maximum viscosity and remarkable breakdown similar to waxy corn starch, but the viscosity increase on cooling was similar to that of the commercial sweetpotato starch.

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