Crude extracts from cashew apple pomace (CAP) dried at different temperatures were used in High-Pressure Liquid Chromatography to quantify total alkaloids content (TAC), total flavanoids content (TFC), total saponin content (TSC) and total phenolics content (TPC). Diphenyl-1-picrylhydrazyl (DPPH) was used to determine the antioxidant capacity (AOC) of CAP. Fourier-Transformed Infrared Spectroscopy-Attenuated Total Reflectance (FTIR-ATR) was used to identify the functional groups present in the pomace. TAC, TFC, TSC and TPC were used as inputs to model AOC using Gaussian Process Regression (GPR), and Support Vector Regression (SVR) and a coupled model was developed using the residuals of GPR and SVR. It was found that increasing drying temperature decreased TAC, TFC, TPC and AOC but TSC increased. Both GPR and SVR predicted AOC with high accuracy. Drying CAP at lower temperature preserved more bioactive compounds hence high AOC; FTIR-ATR showed that CAP has good hydration capacity and contains majorly inorganic phosphates, aliphatic hydrocarbons and primary alcohols. Model coupling enhanced AOC prediction.

Variable-temperature convective drying (VTCD) is a promising technology for obtaining high-quality dried mushrooms, particularly when considering rehydration capacity. However, accurate numerical models for variable-temperature convective drying and rehydration of shiitake mushrooms are lacking. This study addresses this gap by employing a model with thermo–hydro and mechanical bidirectional coupling to investigate five dehydration characteristics (moisture ratio, drying rate, temperature, evaporation rate, and volume shrinkage ratio) and a drying load characteristic (enthalpy difference) during VTCD. Additionally, a mathematical model combining drying and rehydration is proposed to analyze the effect of VTCD processes on the rehydration performance of shiitake mushrooms. The results demonstrate that, compared to constant-temperature drying, VTCD-dried mushrooms exhibit moderate shrinkage rates and drying time (16.89 h), along with reduced temperature variation and evaporation rate gradient (Max. 1.50 mol/(m³·s)). VTCD also improves enthalpy stability, reducing the maximum drying load by 58.84% compared to 338.15 K constant-temperature drying. Furthermore, drying time at medium temperatures (318.15–328.15 K) greatly influences rehydration performance. This study quantitatively highlights the superiority of variable-temperature convective drying, offering valuable insights for optimizing the shiitake mushroom drying processes.