Microwave freeze-drying characteristics and crosslinking behavior of wheat starch-laurel acid complex

This article investigates the effect of different microwave powers on the crosslinking behavior and microwave freeze-drying characteristics of wheat starch-lauroyl arginate complex during the microwave freeze-drying process. During microwave freeze-drying, as microwave power increased from 0.1 W/g to 0.9 W/g, the freeze-drying time of WS-LA was reduced by 50 %, while the uniformity of freeze-drying was not affected by its composition. In the research results obtained from DSC, Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), XRD, and SEM analyses, with the microwave power increased from 0.1 W/g to 0.9 W/g, the enthalpy value of the melting peak of the WS-LA (wheat starch-lauric acid) composite decreased from 1.15 J/g to 0.62 J/g. The full width at half maximum (FWHM) value increased from 25.6 to 30.79. The ratio of absorbance at 1022/995 cm^-1 increased from 1.0111 to 1.0707. The recrystallization (RC) value decreased from 8.77 % to 0.07 %. Additionally, in the microstructure, the size of WS-LA composite particles decreased accordingly. The above findings indicated that the increase in microwave power during microwave freeze-drying had a negative impact on the formation of the WS-LA complex and the ordering of its structure in the sample.