Moisture desorption isotherms and drying kinetics of some wild mushrooms
- Publication Type
- Poster
- Authors
- Argyropoulos, D; Müller, J
- Year of publication
- 2015
- Conference name
- 12th International Congress on Engineering and Food (ICEF12)
- Conference location
- Québec City, Canada
- Conference date
- 14 - 18 June 2015
- Keywords
- Trocknung
Convective air drying of several wild mushroom species, i.e. Cep (Boletus spp.), golden chanterelle (Cantharellus cibarius), black trumpet (Craterellus cornucopioides) and morel (Morchella spp.) is performed in cabinet dryers within a temperature range of 50 and 70 °C. Correctly dried mushrooms intensify their distinctive flavor without significant loss of their color and pleasant texture. However, due to the lack of experimental data, inappropriate drying conditions usually result in dried mushrooms of hard or rigid texture with visible effects of browning. Apart from quality deterioration, over drying induces an additional energy requirement increasing the operational costs. Optimal final moisture content and corresponding water activity is also required to avoid mould formation and insect infestation after packaging. Therefore, the influence of the conditions of drying air (T=50-70°C, x=10-30 g/kg, v=0.2-1.0 m/s) on drying characteristics of some wild mushrooms was investigated during drying in a high precision through-flow dryer. Drying kinetics was described by a first-order reaction kinetics model, in which k is function of the air conditions. Equilibrium moisture contents were determined at (T=50-70 °C, aw=0.10-0.90) using the hygrometric method. Desorption isotherms of all mushrooms were modeled by the modified Oswin equation. Isosteric heats of desorption were calculated as a function of moisture content and temperature directly by the model, in which the Clausius-Clapeyron equation has been incorporated. The effects of humidity and velocity of drying air on drying constant were considered as lower than that of air temperature. Differences in drying behavior and equilibrium moisture content were observed among the mushrooms species. At the same drying conditions, black trumpet was dried faster, followed by morel, whereas chanterelle indicated significantly longer drying periods. The minimum energy required to dry each mushroom species was estimated. The parameters of the model will lead to optimization of the operating conditions in drying practice of mushrooms.