Characteristics of Java Taro Starches and Physical Properties of Acid- and Heat-treated Taro Starches

Abstract

Characteristics of taro corm starches of four kinds were studied as follows: Java and Celebes were harvested in Indonesia; Uhan in China; Satoimo in Japan. In addition, effects of acid- and heat-treatments on physical properties of native Java starch were examined. The particle size of Java starch was in the range of 3-17 μm with about 50% distribution of size of 9-13 μm. From SEM observation, the size of starch granules for Java, Celebes, Uhan and Satoimo was 3.0-13.0, 1.0-4.8, 1.5-5.8 and 0.5-3.4 μm, respectively. The native Java starch was mostly spherical, but some portions of the surface were square with a larger size than for other starch samples. The amylose content of the Java sample determined by the blue value method was 20.5% and number-average degree of polymerization was 880 and 2920 for amylose and amylopectin, respectively. The average chain length of amylose or amylopectin was 17 or 19, respectively. From the result of X-ray diffraction, the crystalline pattern of Java starch was A type. As for DSC results, Satoimo starch was gelatinized at a higher temperature, while the enthalpy was lower than those of other samples. In contrast, starch of Celebes or Uhan was gelatinized at lower temperature, as compared with native Java starch. The gelatinization enthalpy of heat-treated Java starch at 50°C showed the highest value among all samples. But, physical properties (DSC and SEM) of acid-treated Java starch were not distinctly different from those of native Java starch.