Journal of the Japanese Society of Starch Science
Online ISSN : 1884-488X
Print ISSN : 0021-5406
ISSN-L : 0021-5406
Volume 26, Issue 4
Displaying 1-7 of 7 articles from this issue
  • Hirohisa SUZUKI, Yasuhiro HASHIMOTO, Hisao KAWABATA, Toshiaki OHIRA
    1979 Volume 26 Issue 4 Pages 211-216
    Published: September 30, 1979
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
    The kinetics of the oxidation of corn starch granules with sodium hypochlorite were investigated. The reaction, having been reported as a first order reaction, was either first or second order depending on the pH and temperature used during the oxidation. As the lower pH values and the higher temperatures, respectively, in the ranges of pH 8-11 and 20-50°C were used, that is, as the reaction rate increased, the reaction was first order and under the opposite conditions it was second order. There seem to be two steps involved in the oxidation of a heterogeneous system, viz., a diffusion process and a reaction process . It was deduced that the order of the reaction depended upon which of these two steps was the controlling process. The overall activation energy of this reaction was concluded to be approximately 15 kcal/mole. The adsorption equilibrium between corn starch granules and sodium hypochlorite was observed in time of one minute after the start of reaction according to Freundlich adsorption formula and during twenty minutes, too, even though most of oxidants were consumed in the reaction. The oxidation processes, viz., adsorption, consumption and transportation of sodium hypochlorite in the medium and corn starch granules were discussed from the above results.
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  • Behavior of Dissolved Oxygen in the Reaction Mixture and Its Application to Process Control
    Hirohisa SUZUKI
    1979 Volume 26 Issue 4 Pages 217-222
    Published: September 30, 1979
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
    Dissolved oxygen in the reaction mixture during the oxidation of corn starch granules by sodium hypochlorite was measured with a Beckman oxygen analyzer. The dissolved oxygen decreased to almost zero ppm immidiately after the start of oxidation and did not increase again until the latter half of the oxidation reaction. Increase in the amount of dissolved oxygen in the latter half of the reaction was delayed when pH was raised or temperature was lowered or the amount of available chlorine added was increased. This phenomenon was' closely related to the reaction rate. The amount of dissolved oxygen was reciprocally related to the amount, of hypochlorite remaining in the reaction mixture. The curves of concentrations of dissolved oxygen plotted against duration of reaction showed good reproducibility when the experiments were done under the similar condition. This was also the case with the experiment using a larger scale reactor. Not only the amounts of dissolved oxygen but also times of reagents added were recorded on the curves. This measuring method of dissolved oxygen can be applied to control the process for the production of oxidized starch.
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  • Ryoichi MURAKAMI
    1979 Volume 26 Issue 4 Pages 223-230
    Published: September 30, 1979
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
    The process of the solidification from gelatinous state for starch, amylose and amylopectin was investigated. The persuit of the change of this process was carried out by measuring time dependence of relative rigidity at constant temperature with the method of torsional braid analysis. It was attempted to apply reaction kinetics to clarify the entire picture of this process. By assuming that formation of bond is proportional to the increase of rigidity, the relation between rel ative rigidity Gr and retardation time τ was derived, namely ln(Gr-Gr)/(Gr-1)=-t/?N. The above equation implies that plot of ln(Gr-Gr)/(Gr-1) vs. time t should be expressed with the linear relation. This plot in the solidifying process turned out to be represented with three straight lines possessing the different inclination. It was assumed that the first stage of the solidifying process results from entanglement accompanied by approach of molecular chain and the second stage results from formation of bond due to van der Waals force and the third stage results from formation of hydrogen bond . Retardation time τ of the second process (II) and the third process (III) was obtained by the inclination of the above plot. Moreover, the activation energy of the solidifying process was obtained by plot of retardation time τ vs. 1/T (T; absolute temperature). The values are 8.0 kcal/mol (II), 12.8 kcal/mol (III) for starch, 7.3 kcal/mol (II), 19.6 kcal/mol (III) for amylose and 8.9 kcal/mol (II), 6.6 kcal/mol (III) for amylopectin . Successively, by applying the Eyring's theory of rate process to this process, the values of free energy of activation ΔF, enthalpy of activation Δ H and entropy of activation ΔS were calculated. On the other hand, by assuming that time-temperature superposition principle may be applied to the change of Gr in the solidifying process, the apparent activation energy was obtained by plot of shift factor aΤ vs. 1/T. These values are approximately coincident with the values obtained by temperature dependence of retardation time.
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  • Relations between the Physical and Chemical Properties and the Expansion Rate of Potato Starch
    Masayuki SUGIMOTO, Masatoshi TAKAGI, Fujio Goto
    1979 Volume 26 Issue 4 Pages 231-240
    Published: September 30, 1979
    Released on J-STAGE: July 01, 2011
    JOURNAL FREE ACCESS
    The mechanism of heat expansion of the dried starch paste, the intermediate product of ' Ebi-senbei' (shrimp cracker), was investigated and the following results were obtained . 1. The heat expansion rate of the dried paste was proportional to each of the maximum viscosity in amylogram, the swelling power and the intrinsic viscosity, but was reciprocally proportional to the elastic modulus of starch gel. 2. The ratio of the combined phosphorus to total phosphorus was proportional to the expansion rate of the dried paste, while the smaller the total content of calcium and magnesium was, the larger the heat expansion rate became. 3. The stereoscopic microscopical observation of the internal fine structure of the baked products, (Ebi -senbei) supported the above results . 4. From these results, two basic factors were assumed for the mechanism of the heat expansion phenomenon of the dried starch paste. One was the extensibility of amylopectin which was dependent upon the physical and chemical properties of potato starch as well as upon the gelatinizing conditions in the preparation of the intermediate dried starch paste . The second was the positive internal pressure produced by water and air contained in the intermediate dried pasteupon heating. The related industrial problems were also discussed.
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  • On the Heat Expansion of Various Starches
    Masayuki SUGIMOTO, Masatoshi TAKAGI, Fujio GOTO
    1979 Volume 26 Issue 4 Pages 241-252
    Published: September 30, 1979
    Released on J-STAGE: July 01, 2011
    JOURNAL FREE ACCESS
    The mechanism of heat expansion of the dried starch paste was investigated, and the following results were obtained. 1. The bulkiness of the expanded products of wheat and maize starch were increased by increasing the amount of water added to starch and extending the heating time . For any of the tested various starches, the higher the heating temperature, the larger the bulkiness of products. 2. The heat expansion rates of the dried starch paste as measured by the methods reported previously were 3.0-3.5 for wheat and maize, 4.7-5.0 for rice and waxy maize, and 5.8-7.0 for sweet potato, sago, tapioca and potato starches . The minimum hardness of the products was shown by the waxy maize starch (3 .0 kg/cm2), and the hardness of cereal starches were slightly higher than those of the others. 3. The optical and the scanning electron microscopical observations on the swelling and dispersion of granules, and of the internal structures of the baked products supported the above results. 4. It was recognized that the heat expansion rates of various starches were closely related to the physical properties (viscosity by amylograph, swelling power and elastic modulus of starch gels). The reason for the preferred use of potato starch in production of‘Ebi-Senbei’ (Shrimp cracker) was also discussed.
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  • [in Japanese]
    1979 Volume 26 Issue 4 Pages 254-269
    Published: September 30, 1979
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
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  • 1979 Volume 26 Issue 4 Pages e1
    Published: 1979
    Released on J-STAGE: February 23, 2011
    JOURNAL FREE ACCESS
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