Synergistic reduction of oil absorption in wheat flour through two-step annealing and soy protein isolate

This study investigated the effects of a two-step annealing treatment on the physicochemical properties of wheat flour (WF) and wheat starch (WS), with the influence of soy protein isolate (SPI) addition on the oil absorption behavior of annealed starch during frying. The two-step annealing process reduced wheat flour swelling capacity from 10.64 to 7.49 g/g and solubility from 6.58 % to 4.22 %. Among all samples, F-A-WF-10 %SPI (annealed flour fried with 10 % soy protein isolate) exhibited the lowest oil absorption rate (17.70 %) and highest relative crystallinity (7.53 %). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results significantly revealed that the incorporation of SPI reduced the disruption of starch granules caused by frying. These findings elucidate the mechanism by which annealing and protein complexation synergistically inhibit oil absorption in starch-based systems, providing a theoretical foundation and a technical strategy for developing low-fat starch-based fried foods.