Effect of reaction solvent on physico-chemical properties, microstructure and digestive properties of starch-fatty acid complexes

The starch-fatty acid complex is of great significance for digestibility, nutrition and production of starchy foods. To further broaden the application range of starch-fatty acids, rice starch in this paper was complexed with fatty acids using deionized water, sodium sulfate solution, acetone and ethanol to investigate the effects of solvents on physico-chemical properties, microstructure and digestive properties of starch-fatty acid complexes. Results on physico-chemical and digestive properties showed that organic solvents could improve the complex's ability to resist digestion, while the water content could assist in regulating the rigidness of the complex, thereby increasing the degree of insertion of the guest substance into the helical structure of amylose. The complex prepared in an aqueous solution loses the granular structure of natural rice starch, while the composite particles prepared in an organic solvent largely retain the shape of the original rice starch. The study showed that these differences might be due to the different solubilities and affinities of different solvents. Choosing a suitable solvent and adjusting the ratio of the solvents can help improve the degree of complexation and decrease the digestibility of the complex.