Study on F lammulina Velutipes Ready-to-Eat Snacks Prepared by Microwave Vacuum Osmotic Dehydration Combined with Hot-Air Drying

Abstract

Flammulina velutipes ready-to-eat snacks are not commonly known. Response surface methodology was employed to optimize the process parameters in making ready-to-eat snacks. The optimum dehydration condition was found at a sucrose concentration of 30%, a vacuum pressure of −40 ± 1.5 kPa, an osmotic time of 165 s and a microwave intensity of 65 W/g. These parameters resulted in water loss, solid gain and sensory evaluation values of 39.15%, 6.96% and 7.87, respectively. The water diffusion rate and solid gain diffusion rate were 1.55 × 10−9 and 1.29 × 10−9 m2/s, respectively, when employing the optimum microwave vacuum osmotic dehydration (MVOD) parameters. When F. velutipes mushrooms were dried for 180 min by hot-air drying, the water content of the ready-to-eat snack was 9.8 ± 0.5% and the water diffusion rate was 1.14 × 10−11 m2/s. Both the MVOD and the hot-air drying stages were consistent with the Page model. Practical Applications Osmotic dehydration technology combined with other drying technologies, such as hot air, can improve the use value and economic benefits of fruits and vegetables. The two correlations developed by modifying second-order polynomial equations were adequate to predict the responses for the Flammulina velutipes samples. The water and solid effective diffusion rates were calculated at different microwave vacuum osmotic dehydration times and different hot-air drying times for F. velutipes mushrooms. The Page model could be used to illustrate the water loss and solid gain for these two drying stages. The F. velutipes mushroom snacks made using these conditions had good color, high gloss and a moderately soft texture, with a sweet and sour flavor. The developed mathematical models can be considered precise for the prediction and optimization of process parameters in experimental and industrial applications.