Changes in textural and optical properties of oyster mushroom during hot air drying

Textural (hardness, cohesiveness, springiness, and chewiness) and optical (spectral surface reflectance) properties of paddy straw mushroom (Pleuratus spp.) were monitored during hot air drying of mushrooms in a cabinet tray drier at different air temperatures 50, 55, 60, and 70 degrees C. Effect of pre-drying treatments, viz. blanching and sulphitation, was also monitored. Texture Analyser (TM) and Hunterlab (TM) Colorimeter were used to determine textural and optical properties, respectively. During drying, hardness and chewiness of mushrooms were increased, while cohesiveness and springiness increased initially and decreased at the final stage of drying. Hardness of mushroom dried at higher temperature was higher. Cohesiveness decreased with increased drying temperature. Blanched and dried mushrooms had more hardness compared to other dried samples. Whiteness index of mushrooms decreased while yellowness index increased during drying. Drying temperature had an inverse effect on whiteness of mushrooms. Sulphitation helped while blanching deteriorated whiteness retention during drying. (c) 2006 Elsevier Ltd. All rights reserved.