Physicochemical properties and digestibility of potato starch treated by ball milling with tea polyphenols.

Native potato starch (NPS) with tea polyphenols (TPs) was treated in a planetary ball mill, and the effects of co-grinding on properties and digestibility of starch were studied. The X-ray diffraction (XRD) results showed that the crystal structure of starch granules was destroyed after 7 h of ball grinding, and their crystallinity degree reduced from 38.1% to 8.3%. The scanning electron microscopy (SEM) analyses indicated that the damaged starch granules and TPs displayed agglomerates after 7 h of milling. The Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) results demonstrated the existence of an interaction between starch chains and TPs, which improved the thermal stability and gelatinization temperatures of starch. The ball-milled starches with different amount of TPs showed significant variability to in vitro digestion (the contents of slowly digestible starch and resistant starch). Therefore, the produced ball-milled mixtures may be a desired dietary product for postprandial glycemic control.