Physicochemical and functional properties of starch from two species of Curcuma

The properties of starch extracted from two species of Curcuma viz. Curcuma zedoaria and Curcuma malabarica were studied. The starch from C malabarica tubers was white in color, while that from C. zedoaria was slightly yellowish due to the presence of the yellow pigment, curcumin. The granule size and shape, amylose content and solubility did not show noticeable difference between starches from the two species. Both the starches possess "B" type x-ray diffraction pattern. Curcuma zedoaria starch showed a lower peak viscosity and swelling volume when compared to C. malabarica starch. The complete removal of curcumin from C zedoaria starch by alcohol extraction, resulted in an increase in the swelling and viscosity values close to those of C malabarica starch. The breakdown in viscosity was quite low for both the starches and setback was higher when compared to cassava and sweet potato starches. The experiments showed that Curcuma starch resembles Dioscorea starches in most of its properties. Differential scanning calorimetry (DSC) data showed that the onset of gelatinisation was earlier for C. malabarica starch. The enthalpy of gelatinization was almost same for both the starches. The phosphorus content of Curcuma starch was quite high and similar to that of Potato starch. The Curcuma starch was found to be easily digestible like arrowroot starch as seen from the in vitro alpha-amylase digestibility patterns. Owing to the high viscosity stability and digestibility, it can be a potential source of starch for food and industry.