Effects of pulsed electric field treatment on the preparation and physicochemical properties of porous corn starch derived from enzymolysis

Abstract

Porous corn starch preparation by enzymolysis and pulsed electric field treatment (PEF) and its physicochemical characterizations were investigated in this study. The best processing parameters of enzymolysis and PEF treatment designed by response surface methodology were 3.9 hr, 11.5 kV/cm applied for 18 ms, respectively, resulting in the highest oil absorption value of 130%. The solubility and transparency of native corn starch were increased after enzymolysis or PEF treatment, and the values were the highest when starch was treated with the combined method. Pasting temperature and gelatinization enthalpy of porous starch were higher than that of native starch, but then decreased significantly after PEF treatments. Scanning electron microscope images, specific surface area as well as X-Ray Diffraction directly reflected the reinforcement effect of PEF treatment on the micropores formation of porous starch. These results indicate that PEF is expected to be used to assist the production of porous starch. Practical applications Starch materials are able to dehydrate water from ethanol due to the existence of numerous hydroxyl groups on the surface, porous starch granules possesses larger specific surface area, which increases the total number of hydroxyl groups on starch particles’ surface. Increased surface area provides more reactive sites at which functionalized groups can be grafted to improve starch properties as well. In addition, numerous small pores enable porous starch to encapsulate compounds of several times its weight by the absorption and capillary flow of micropores, especially heat-liable compounds like flavor molecules, plant essential oils, biologically functional compounds, for example, liquid flavors are unstable under heat processing, mixtures of which could be spry-dried with porous starch to obtain flavor powder, prolonging the storage time of flavor compounds. And the combination of enzymolysis and PEF treatment is good for the micropores formation of porous starch, which could be used to produce porous starch for industrial application.