Facile Production of Purple Sweet Potato Porous Starch as Low Cost Food-based Adsorbent for Microencapsulation

This study aimed to develop a facile synthesis process of porous starch wall materials from purple sweet potato (PSP) for microencapsulation via enzymatic treatment. The optimum extraction conditions of purple sweet potato starch (PSP-S) were first attained by an orthogonal experiment. Response surface methodology was performed through the enzymatic hydrolysis of PSP-S using an a-amylase and glucoamylase complex to optimize the process parameters for the production of porous starch. Optimal reaction conditions were: the mass ratio (w/w) of glucoamylase to a-amylase of 6.39, amount of substrate of 19.5 g, and amount of enzymes of 0.53%. The surface morphology, microstructure, and thermal stability of the obtained samples were characterized with scanning electron microscopy, Fourier-transform infrared, and thermogravimetric analyses, respectively. The purple sweet potato porous starch (PSP-PS) had a stable oil adsorption capacity, and the molecular structure and thermal stability of porous starch were not substantially different from those of native starch. This study offers a simple yet efficient approach to produce fully biodegradable food-based porous materials for potential applications in oil microencapsulation.