Preparation of adzuki bean starch-lipid complexes and their anti-digestion mechanism

Starch-lipid acid complexes (SLCs), as a new modified starch, have become a research hotspot in recent years because of their anti-digestive properties, which can reduce postprandial blood glucose levels, and are beneficial to chronic diseases such as type 2 diabetes and obesity. The aim of this study was to investigate the effects of fatty acid (FA) chain length on the physicochemical properties and digestibility of adzuki bean starch (ABS) complexes, as well as the anti-digestion mechanism of these SLCs. The dimethyl sulfoxide dispersion method was used to prepare the adzuki bean SLCs by complexing ABS with FAs of four different chain lengths: lauric acid (C12), myristic acid (C14), palmitic acid (C16) and stearic acid (C18). The results showed a significant increase in the resistant starch (RS) content of the SLCs compared with pure ABS. The anti-digestibility of the complexes was significantly negatively correlated with FA chain length. Fourier transform infrared spectroscopy (FTIR) revealed that there were no chemical changes between the starch and lipids. X-ray diffraction (XRD) analysis indicated that the complexes exhibited a V-shaped crystal structure. Differential scanning calorimetry (DSC) showed that the introduction of FAs significantly improved the thermal properties of the starch. The relevant conclusions from the mechanism of digestibility were verified by enzymatic hydrolysis kinetics. The results indicated that the FA structure significantly affects the structures of the complexes, further affecting their physicochemical and digestive properties.