Effect of Slice Thickness, Pre-treatments, and Drying Methods on Drying Characteristics of Milky Mushroom (Calocybe indica)

Abstract

Drying characteristics of milky mushroom (Calocybe indica) of APK 2 variety was studied by cabinet drying, fluidized bed drying, and sun drying. Air temperatures of 50, 60, and 70°C were used in the cabinet and fluidized bed dryer. Air velocity of 7-8 m.s-1 was used in the fluidized bed dryer. Temperature observed under open sun drying was 28 - 32°C at relative humidity of 55 – 65%. Mushroom slice of 10, 15, 20 mm thickness were hot water blanched at 85°C for 3 minutes, and treated with potassium meta-bisulphite (KMS) @ 200 ppm per litre of water for 15 minutes, as treatments with a control. Mushroom samples with the initial moisture content of 747.8- 1500.4% (d.b.) were dried to a final moisture content of 7.8- 16.7% (d.b.) by the sun in 10.5 - 15.5 h, fluidized bed in 1.5 - 2.75 h, and cabinet drying in 5.5 - 13.5 h. Drying time increased with increase in thickness of the sample, and decreased with increase in drying air temperature. The protein content of the samples dried by cabinet, fluidized bed, and sun drying were 34.8, 33.3, and 29.7%, respectively. Drying at 50°C under cabinet and fluidized bed drying retained higher protein content..