Optimization of Variable-Temperature Pressure-Difference Puffing Drying Process for Persimmon Chips Using Response Surface Methodology

This study focused on persimmons and applied variable-temperature pressure-differential puffing drying to produce persimmon chips. The effects of puffing pressure, holding time, drying temperature, and duration on moisture content, crispness, and sensory scores were examined. The optimal parameters determined via response surface methodology were a pressure differential of 0.46 MPa, holding time of 10 min, drying temperature of 94 °C, and drying time of 92 min, achieving a moisture content of 3.63%, crispness of 362.83 g, and sensory score of 90.8. Microstructural and porosity analysis showed that this method predominantly produced chips with large pores and enhanced pore volume (0.2949 cm3/g), porosity (30.16%), and average pore diameter (194.0 nm). Compared to microwave drying, vacuum microwave drying, and vacuum frying, the pore volume of persimmon chips processed using pressure-differential puffing drying increased by 57.7% to 237.8%, the porosity improved by 57.2% to 237.8%, and the average pore diameter grew by 82.2% to 660.8%. Notably, the differences were most pronounced when compared to vacuum frying, with increases of 237.8%, 237.8%, and 660.8%, respectively. These results indicate that pressure-differential puffing drying is superior in creating loose structures and achieving high-quality persimmon chips, making it the preferred processing method.