Process Optimization and Quality Analysis of Purple Sweet Potato Puffed Rings by Twin-Screw Extrusion
The effects of water content,puffing temperature,screw speed,and feed speed on the swelling de-gree 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,respec-tively,which were close to the predicted values.In addition,the puffed rings showed improved hydration prop-erty,gelatinization stability,and anti-aging property,with a crisp taste and easiness of cutting.