Introduction of chlorogenic acid during extrusion affects the physicochemical properties and enzymatic hydrolysis of rice flour

To investigate how chlorogenic acid (CHA) affects the physicochemical properties and hydrolysis of rice flour during extrusion. CHA was extruded with rice flour through a twin-screw extruder at different concentrations (0–2.0%), and the physicochemical properties of the extrudates, including crystallinity, pasting properties and CHA binding, were characterized through X-ray diffraction, Fourier-transform infrared spectroscopy, Rapid Visco Analyzer and ultraviolet spectrophotometer. Particularly, starch hydrolysis and the release of CHA were also evaluated through enzymatic hydrolysis and high-performance liquid chromatography. Results indicated that the addition of CHA promoted the formation of V-type crystals and increased the orderliness of the complexes. The maximum binding amount of CHA in extrudates was 10.98 mg/g without any isomerization or degradation. Additionally, the rapidly digestive starch (RDS) decreased markedly (down to 41.28 ± 2.66%), and there was a pronounced increase in resistant starch (RS), which varied from 10.28 ± 2.62 to 31.16 ± 0.50% in different extrudates. Our results indicated that CHA yielded a negative effect on starch hydrolysis and might provide basic guidance for the application of CHA to healthy starchy food processing in the future.