Preparation and characterization of low oil absorption corn starch by ultrasonic combined with freeze–thaw treatment

This study investigated the effects of ultrasonic, freeze–thaw, and combined pretreatments on corn starch oil absorption. Low-field nuclear magnetic resonance (LF NMR) was used to study the oil absorption changes after frying of corn starch (CS) subjected to different treatments. The structural characteristics of samples were evaluated using various techniques. Scanning electron microscopy, contact angle, and particle size analysis showed that corn starch subjected to combined ultrasonic and freeze–thaw treatment generated larger, coarser particles with a denser structure. Furthermore, X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry showed that combined treatment improved the order and thermal stability of CS molecules, thereby inhibiting oil absorption during frying. The results showed that combined ultrasonic and freeze–thaw pretreatment significantly reduced the oil absorption of corn starch before and after frying.