Characteristics of acetylated and enzyme-modified potato and sweet potato flours

The properties of modified potato and sweet potato flours have been determined by incorporating acetyl groups (acetylation) and by treating with glucoamylase (enzymatic modification). Fractionation studies on Sepharose CL-2B showed that the content of high molecular weight fraction decreased, with a proportionate increase in the lower molecular weight carbohydrate fraction, whereas FT-IR indicated changes in crystallinity of the modified starches. The data showed that the degradation of starch is dependent on the type of modification which, in turn, determined its crystallinity and digestibility. The swelling power and solubility patterns of modified flours indicated a greater degree of associative forces in the starch granules. Scanning electron microscopy revealed indentation on acetylated starch granules, and the granules appeared as bunches/clusters, whereas surface erosion was observed in the enzyme-treated samples. The presence of substituent groups in acetylated flour influenced digestibility inversely, whereas improved digestibility was observed in enzyme-modified samples.