Isolation and physico-chemical properties of enset starch

Enset starch (Ensete ventricosum, Musaceae) has been examined for its chemical composition, amylose content and physico-chemical properties. The proximate composition of the starch on dry weight basis was found to be 0.16% ash, 0.25% fat, 0.35% protein, and 99.24% starch. The amylose content was 29%. Scanning electron microscopy (SEM) of enset starch granules showed characteristic morphology that was somewhat angular and elliptical. The starch has normal granule size distribution with a mean particle size of 46 mu m. It exhibits typical X-ray diffraction pattern of B-type with a distinctive maximum peak at around 17 degrees 2 Theta. Its moisture sorption pattern was similar to that of potato starch. Its swelling power and solubility values were lower than potato starch but much higher than maize starch. DSC parameters obtained from starch-water mixtures (1:2), namely, the enthalpy of gelatinization (Delta H: 21.6mJmg(-1)), the onset temperature (T-0: 61.8 degrees C), the peak temperature (T-p: 65.2 degrees C) and the endset temperature (T-e: 71.7 degrees C) were higher than those obtained for potato starch. Brabender viscosity curves of 6% starch paste showed lower peak viscosity (884 BU) than potato starch (1668 BU) but greater than maize starch (302 BU). The breakdown was also lower than potato starch but higher than maize starch. Retrogradation of enset starch was substantially greater than potato starch but less than maize starch.