Effect of Solvent Extraction on the Gelatinisation Properties of Flour and Starch of Five Cassava Varieties

Abstract

The gelatinisation properties of native and solvent-extracted (petroleum ether and ethanol) flour and starch processed from five cassava varieties grown in India were studied using a differential scanning calorimeter (DSC) and a Brabender amylograph. Varieties varied in their DSC peaks but these remained unaffected by solvent extraction, indicating that the DSC profiles are characteristic of these starches. In general, the gelatinisation temperatures of the flours were significantly higher than those of the starches but the enthalpy of gelatinisation was less for flour. Varietal differences were also observed in the gelatinisation profiles of starch and flour samples obtained using the Brabender amylograph. Lower viscosity values were obtained for the flour samples but values remained more stable throughout the temperature programme. In most varieties, solvent extraction of the samples caused only slight modification of the gelatinisation patterns. There was no apparent relationship between the gelatinisation properties of the starch derived from the different varieties and the size and amylose content of the starch granules. Results of these experiments indicate that differences in gelatinisation values obtained, between starch and flour samples for the same variety, are not due to the presence of sugars and fats which were removed by ethanol and petroleum ether extraction, respectively. The significant differences observed in some varieties are therefore due to the presence of other root constituents.