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

This study examined how fatty acids of varying chain lengths influence the microwave freeze-drying (MFD) properties and cross-linking interactions in wheat starch-fatty acid complexes. The study revealed that fatty acids with extended carbon chains decreased the initial water content in wheat starch-fatty acid blends, thereby reducing the drying time. Long-chain complexes maintained a more stable freeze-drying rate with changes in experimental power compared to short-chain ones. When microwave power was raised from 0.5 to 2.5 W/g, the enthalpy shifts (ΔH) in melting peaks for starch-fatty acid complexes varied significantly: butyric acid blends showed a change of 176.71 J/g, octanoic acid 714.06 J/g, and myristic acid 1102.02 J/g. XRD revealed reductions in relative crystallinity by 12.87%, 19.38%, and 27.00%. Raman spectroscopy showed peak width increases at 480 cm -1 of 8.22, 8.49, and 10.43, respectively. The extent to which wheat starch-fatty acid complexes were affected during MFD increased with the chain length of the fatty acids. • Provides a theoretical basis for developing starch-based dehydrated foods. • Microwave freeze-drying was used to produce low cost and high quality WS-FA complexes. • WS-LFA complexes are more sensitive to microwave freeze-drying.