Abstract:The effects of water content，puffing temperature，screw speed，and feed speed on the swelling degree and hardness of purple sweet potato puffed rings prepared with the purple sweet potato cultivar ′Xuzishu 8′ were studied. The twin-screw extrusion conditions were optimized by single factor experiments combined with Box-Behnken design. Furthermore，the hydration，gelatinization，and texture characteristics of the puffed rings were analyzed. The results showed that the optimal preparation conditions were water content of 12%，puffing temperature of 149 ℃，screw speed of 28 Hz，and feeding speed of 10 Hz. The purple sweet potato puffed rings prepared under these conditions had the swelling degree of 3.52 and hardness of 63.85 N，respectively，which were close to the predicted values. In addition，the puffed rings showed improved hydration property，gelatinization stability，and anti-aging property，with a crisp taste and easiness of cutting.