Modeling of vacuum drying of pressed mycelium (Pleurotus eryngii) and its microstructure and physicochemical properties

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AbstractMycelium is the vegetative part of the fungus that grows and forms fruiting bodies, called mushrooms. The Pleurotus eryngii variety mycelium is highly nutritious but perishable due to its high moisture content, making its drying necessary for further application. Pressing as a novel pre‐treatment was applied to fresh mycelium from 3 to 5 kN force for 20–50 s, and its effect on drying time was observed. The pressed mycelium was further vacuum dried at different temperatures (40–60°C) and pressure (60–260 mmHg) conditions. The drying data was fitted with 10 thin layer drying models, and Akaike information criteria was applied for selecting the best model. The physicochemical properties like browning index (BI), water activity (aw), water absorption index (WAI), water solubility index, and flowability were calculated. The study found that pressing at 5 kN for 30 s reduced the moisture content from 89% to 52% wb and drying time by 48%–50%. The drying curves showed lower drying time at higher vacuum and temperature conditions. The drying modeling suggested the best fit for Page, Wang and Singh, Verma, and Midilli models (R2 > .9867, RMSE < .0514, SSE < .0112). The Akaike information criterion showed that the Midilli model is in good agreement with drying data (Akaike increment = 0) at seven conditions. Mycelium dried at 60°C and 60 mmHg showed less aw (0.215 ± 0.004) and BI (28.946 ± 0.066), and maximum WAI (5.365 ± 0.046 g/g). Flowability of the dried mycelium is not affected (p < .05) by vacuum drying conditions.Practical ApplicationsPressing as a non‐thermal pre‐treatment for drying can be used to reduce the drying time thereby saving the energy. As a natural fortificant, vacuum‐dried mycelium has potential in improving the nutritional status of the food products. Furthermore, the drying modeling will aid in the creation of optimum drying conditions for mycelium and the design of a commercial‐scale continuous drying system.