Optimization of explosion puffing drying process at variable temperature and pressure for mushroom stem by response surface methodology

In order to optimize the technology for explosion puffing drying of mushroom stem,the central composite design of response surface methodology was adopted. The effect of puffing temperature( X_1),vacuum drying temperature( X_2) and vacuum drying time( X_3) on moisture content( Y_1),color( Y_2) and puffing degree( Y_3) of product were studied. Based on the experimental data,the quadratic regression models of three indexes were deduced,then variables were analyzed with response surface methodology. The optimal puffing drying conditions were determined as 86 ℃ of puffing temperature,69 ℃ of vacuum drying temperature,2 h of vacuum drying time.Under this condition,the moisture content,color and puffing degree of mushroom stem were 3.83%,42.29 and0.685.Compared with hot air drying,the technology has a better puffing effect,and can be applied to puffed product of mushroom stem.