Impact of solvent polarity on the morphology, physicochemical properties, and digestibility of A-type resistant starch particles

Resistant starch particles (RSP) formed by antisolvent precipitation method has attracted much attention as a functional food ingredient having beneficial effects on obesity and diabetes. However, the effect of solvent polarity on the physicochemical properties and digestibility of RSP remains unclear. Here, n-propanol, isopropanol, acetone, and ethanol were employed as antisolvents to prepare RSP. The width and length of the resulting RSP decreased from 0.87 μm to 0.59 μm and from 2.56 μm to 1.31 μm, respectively, upon increasing the solvent polarity, while dramatically decreasing their crystallinity and the gelatinization enthalpy from 80.5% to 62.3% and from 67.9 ± 14.4 J/g to 41.5 ± 8.3 J/g, respectively, suggesting that solvent polarity is critical factor determining morphology, crystallinity, and thermostability of RSP. Furthermore, the level of resistant starch in RSP was found to be inversely proportional to the degree of solvent polarity, which would provide a useful means for modulating the digestibility of RSP.