Surface Modification of Tapioca Starch by Using the Chemical and Enzymatic Method

Surface modifications of starch provide benefits in various applications for food and medical products as a carrier material due to their high adsorption ability. The effect of enzymatic and acid modification of starch surfaces on the morphology and characteristics of granular tapioca starch is investigated. Tapioca starch slurry is prepared and treated with alpha-amylase (alpha A), amyloglucosidase (AM), the combination of these two enzymes (alpha A+AM), and 2.2 m HCl (AS) at various hydrolysis times. Starch granular surface of alpha A, AM, and alpha A+AM-treated samples show voids and cavities. The AS sample induced more surface roughness in the granules as compared to the enzyme-treated samples and some parts of the granules are smaller or fused together into a larger size. The highest relative crystallinity is obtained from the AS samples (48.43%). All modified samples exhibit an increase in their specific surface area, volume of pores, and average diameter. The AM sample shows the highest specific surface area (1.66 m(2) g(-1)) which corresponds to the largest pore volume (0.38 cm(3) g(-1)) while the AS sample shows the highest average diameter (21.87 nm). Overall, a modified granular starch surface with various characteristics can be provided by using hydrolysis enzymes and acid.