Effect of static magnetic field pretreatment on the structure and oil absorption properties of normal maize starch

In this work, we report the effect of static magnetic field (SMF) on normal maize starch (NMS) structure and oil absorption properties. The results showed that the untreated NMS had the total oil absorption of 83.90%, solubility of 19.00%, swelling power of 20.32 g/g, and amylose content of 26.95%. Besides, compared with un-treated NMS, pretreatment with different SMF strengths significantly reduced the total oil absorption (61.78-78.12%), solubility (16.99-18.61%), swelling power (17.62-19.02 g/g), and amylose content (19.77-24.73%) of NMS. Besides, the SMF-pretreated NMS had a rough surface with more pits and pores, a denser particle structure, and a smaller specific surface area and particle size than untreated NMS. However, the high SMF intensity (50 mT) made NMS form a porous structure, leading to the highest oil absorption of NMS (78.12%), but still less than untreated NMS (83.90%). FT-IR, XRD, and DSC studies further showed that SMF pretreatment improved the structural ordering and thermal stability of NMS particles, inhibiting the oil ab-sorption of NMS. To investigate whether SMF pretreatment could reduce starch-based fried food oil absorption, LF-NMR was used to determine the oil content of fried NMS treated with different SMF strengths. Results indicated the oil content of NMS after frying was significantly reduced by SMF pretreatment than untreated NMS, and the lowest was 0.2751 g/g for SMF-30. Therefore, SMF pretreatment can effectively reduce the oil absorption capacity of NMS before and after frying and serve as a prospective technology to reduce the oil content of starch-based fried foods.