Effect of starch modification on physico-chemical, functional and structural characterization of cassava starch (Manihot esculenta Crantz)

Abstract

Starch extracted from cassava was subjected to chemical and enzymatic modification. Extracted native starch and modified starches were evaluated for proximate analysis and then assessed for different functional properties such as water-binding capacity, swelling power and solubility. Chemically and enzymatic modified starches recorded higher waterbinding capacity i.e. 89.69% and 96.10% respectively and higher solubility 80.33% and 79.66% respectively as compared to native starch having the water-binding capacity 70.63% and solubility 25.18%. Scanning electron microscopy revealed round to polygonal in shapes with smooth surface for native starch and spherical to oval shaped granules for chemically modified starch. Enzymatic modified starch showed relatively rough surface, pores and cracks on surface fissures. X-ray diffractograms showed typical ‘B’ for pattern native starch but in modified starches showed typical ‘A’ pattern comparatively reduced peak and covers a larger area. FT-IR Image of starch and modified starch showed the typical peaks for the starch backbone. The O-H (alcohol) stretching band in the region 3500–3000 cm-1 was found to be broadened and became less sharp, strong and broad in the spectra of the native and chemical modified starch, in comparison to that of the enzyme modified starch. Functional properties of starch such as water-binding capacity and solubility of starch granules increased by chemical and enzymatic modification.