The effects of extrusion temperature on the physicochemical properties and in vitro digestibility of yam flour were studied by using the same direction twin-screw extruder. The flour was extruded under the conditions of different temperatures (90, 100, 110, and 130 ℃) with a screw speed of 180 r/min and the feed moisture of 30%. The results showed that the crystallinity of yam flour decreased with the increase of extrusion temperature, and the crystal structure changed. After extrusion, the solubility of the flour was increased, while the expansion degree and the gelatinization enthalpy decreased. With the increase of extrusion temperature, the highest solubility and the lowest expansion degree and gelatinization enthalpy were obtained at 130 ℃. The dynamic rheology of yam flour showed weak gel properties. In the range of frequency scanning, the energy storage modulus (G') and loss modulus (G″) of yam flour decreased with the increasing of temperature. The results of in vitro starch digestion showed that the content of starch with slow digestion properties increased and the content of resistant starch decreased. Meanwhile, the overall digestibility increased after extrusion, and the content of slowly digested starch increased with the increase of temperature. Therefore, when the extrusion temperature was 130 ℃, the flour was stable and not easy to gelatinization. It had a good water-soluble and the content of slowly digested starch was higher than that of untreated flour. The extrusion process could improve the functional properties and quality of the food by affecting the structure and in vitro digestibility of the flour.
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