Drying and Rehydration of Sullius luteus Under Different Pretreatments: Kinetic Modeling, Rehydration, and Chromatic Changes

Edible mushrooms (Suillus luteus) represent valuable sources of nutrients and bioactive compounds that are sensitive to drying conditions. The objective of this study was to determine the drying time, kinetic model, effective diffusivity, activation energy, and color changes in S. luteus samples subjected to convective and vacuum drying at 70 and 50 °C, respectively, following pretreatments with 1% citric acid or blahing. The shortest drying time to reach equilibrium moisture was 14 h at 70 °C under a vacuum, whereas the longest was 44 h at 50 °C under convective drying. The Midilli, logarithmic, and Henderson and Pabis models provided the best fits for vacuum drying. The effective moisture diffusivity values ranged from 5.83 × 10−9 m2s−1 at 50 °C to 1.159 × 10−8 m2s−1 at 70 °C, while the mean activation energies for vacuum and convective drying were 10.27 kJmol−1 and 24.7 kJmol−1, respectively. The highest rehydration capacity was observed in untreated samples dried under a vacuum, with a value of 3.5 g H2O/g dry matter, whereas convective drying yielded 2.4 g H2O/g dry matter. The greatest shrinkage with respect to thickness was observed in those treated with citric acid and blanching. Correlation analysis of color revealed a strong negative relationship between lightness (L*) and total color difference (ΔE), as well as high positive correlations among a*, b*, and C*, suggesting that color transformations occur jointly throughout dehydration. The findings indicate that effective diffusivity increased with temperature, untreated samples exhibited greater water loss, and rehydration ratios were higher in untreated compared with pretreated samples.