Effects of fatty acids with different degrees of saturation on the microwave freeze-drying characteristics and cross-linking behavior of wheat starch-fatty acid complexes.

This study aims to investigate the effect of fatty acids with different degrees of saturation on the microwave freeze-drying (MFD) characteristics and crosslinking behavior of wheat starch-fatty acid composite systems. In the composite system, with the increase in the unsaturation of fatty acids, the initial moisture content also increased. In terms of drying characteristics, both the MFD curve and the MFD rate curve indicate that composite systems of wheat starch with higher unsaturation levels respond more stably to changes in microwave power throughout the MFD process. During the MFD of wheat starch-stearic acid, wheat starch- oleic acid and wheat starch- linoleic acid, as the microwave power was elevated from 0.5 W/g to 2.5 W/g, the DSC results showed changes in the melting enthalpy (ΔH) of 2475.31 J/g, 643.32 J/g, and 2157.80 J/g, respectively. The XRD results indicated that the relative crystallinity (RC) decreased by 37.70 %, 17.56 %, and 29.70 %, respectively. The FTIR results revealed an increase in the ratio at 1022/995 cm by 3.79 × 10, 0.21 × 10, and 0.25 × 10, respectively. The CI of the three composite systems decreased by 23.98 %, 2.14 %, and 12.48 %, respectively. In other words, the composite of wheat starch and monounsaturated fatty acid was more stable during the MFD process compared to the composites of wheat starch with saturated fatty acids and wheat starch with polyunsaturated fatty acids.