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KMID : 0665220120250041068
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Korean Journal of Food and Nutrition
2012 Volume.25 No. 4 p.1068 ~ p.1074
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Effect of Ohmic Heating at Subgelatinization Temperatures on Thermal-property of Potato Starch
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Cha Yun-Hwan
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Abstract
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Ohmic heating uses electric resistance heat which occurs equally and rapidly inside of food when electrical current is
flown into. In other study, we researched about soybean protein’s characteristic changes by ohmic heating. Nevertheless
treated same temperature, denaturation of soybean protein were accelerated by ohmic heating than conventional heating. In this time, we studied thermal property change of potato starch by ohmic heating besides conventional heating. For this
purpose, potato starch was heated at same subgelatinization temperature by ohmic and conventional heating. And thermal
properties were tested using DSC. Annealing of starch is heat treatment method that heated at 3～4% below the gelatinization point. DSC analysis results of this study, the To, Tp, Tc of potato starch levels were increased, whereas Tc～To was narrowed. This thermal property changes appear similar to annealing’s result. It is thought the results shown in this study, because the heating from below the gelatinization point. 6, 12, 24, 72, and 120 hours heating at 55℃ for potato starch, To, Tp, Tc values continue to increased with heating time increase. The gelatinization temperature of raw potato starch was 65.9℃ and the treated starch by conventional heating at 55℃ for 120 hr was 72℃, ohmic was 76℃. The gelatinization range of conventional (72 hr) was 10℃, ohmic was 8℃. In case of 24 hours heating at 45, 50, 55, 60, 65℃ for potato starch, the result was similar to before. To, Tp, Tc values continue to increased and gelatinization range narrowed with heating temperature increase. In case of conventional heating at 60℃, the results of gelatinization temperature and range were 70.1℃ and 9.1℃. And ohmic were 74.4℃ and 7.5℃. When viewed through the results of the above, the internal structure of starch heated by ohmic heating was found that the shift to a more stable form and to increase the homology of the starch internal structure.
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KEYWORD
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ohmic heating, conventional heating, potato starch, subgelatinization temperature, thermal property, differential scanning calorimeter (DSC)
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