Effect of pulsed electric fields treatment on the nanostructure of esterified potato starch and their potential glycemic digestibility

Esterified starch macromolecules were studied in relation to the effects of pulsed electric fields (PEF) on in vitro digestibility and emulsion stability. The results show that starch acetates with higher electric intensity yielded emulsion with lower oil layer separation over a 30 days shelf life trial. The in vitro digestion suggests the quantity of slowly digestible starch (SDS) fractions increased from 6.63% in the control sample to 17.53% at 3.75 kV/cm. Scanning electron microscopy, X-ray diffraction, small-angle X-ray scattering and atomic force microscopy were used to determine the crystalline and nanostructure. The surface of native starch (as observed in the nanosheet images) exhibited a low roughness value (Ra = 0.639 nm), while starch acetates displayed an increase in surface roughness ((Ra = 0.766 nm (non-PEF) and 1.176 nm (PEF-combined)). The results illustrate that PEF has an important impact on the emulsification and SDS contents of potato starch granules. Industrial relevance: Pulsed electric fields (PEF) are a technique widely used to improve the sterilization efficiency and help modify macromolecules. The present paper evaluates the potential applications of chemically modified potato starch molecules assisted by PEF process. Based on the investigation of the nanostructure and crystalline texture, the effect of PEF acted on esterificated starch macromolecules is proposed to explain these changes occurred to properties. The results have also demonstrated that the PEF treatment applied on esterification did promote the digestibility and emulsification stability of the product. Through the PEF treatment shows high potentials to be applied with esterification at an industrial level to enhance the reaction efficiency and to obtain novel products with better glycemic digestibility and emulsion stability.