Preparation and Structure Characterization of Tea Polyphenols-high-amylose Maize Starch Co-grinding Mixtures

To improve the content of resistant starch(RS),the ball milling technique was used for treatment of tea polyphenols(TPs)and high-amylose maize starch(HAMS)mixtures. The structure,morphology,and thermal stability of co-grinding mixtures were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and thermogravimetric analysis(TGA),and their nutrient fragments(RDS SDS and RS)were evaluated by simulated in vitro digestion. The XRD results indicated that the crystallinity of starch granules in the obtained mixture decreased gradually with the increase of milling time. After 3 h milling treatment,the crystallinity of starch decreased from 38.1% to 8.3%. The SEM analysis showed that the starch granules expanded,their surface became relatively rough,some of starch granules ruptured,the TPs and HAMS gradually became adhesion during the co-grinding process. The TGA results showed that the co-grinding mixtures had lower thermal stability than HAMS,however,their thermal stability was higher than that of TPs. After co-grinding,when the mass ratio of TPs to HAMS increased from 1:50 to 1:10,the content of RS in the co-grinding products increased from 6.31%±0.88% to 31.92%±1.53%. After the co-grinding treatment,the crystallinity of the mixture of tea polyphenols and high amylose starch was reduced,the surface of the morphology changed to become rough particles,the thermal stability was reduced,and the content of resistant starch increased.