assessment of an ultraviolet- assisted continuous infrared dryer for producing intermediate moisture food from mushroom slices

The present study was aimed to develop and experimentally investigate a novel uv-assisted continuous ir dryer (uvaird) to produce intermediate moisture foods (imf) from mushrooms.the effect of the drying temperature at t the levels of 45, 55, and 65 °c, the forward speed of the belt at three levels of 15, 20, and 25 mm/min at two operating modes of uv-on and uv-off were investigated on the specific energy consumption (sec), infrared fraction (irf) of the dryer as well as final moisture content (fmc), and some quality indices of the products. the results showed that raising the speed decreased irf, but it was significant only when the uv lamps were on. increasing the air temperature increased sec values by 32.4%, and 33.55% at the uv-on and uv-off, respectively. fmc values increased with increasing speed by 80.49% and 55.70%, uv-on and uv-off, respectively. the hue angle (h°) decreased during the storage period, but the decreasing slope was lower at the mode of uv-on than the uv-off. total microbial counts of intermediate moisture mushrooms were in a range of 6.55-6.74 log cfu/g of products. the values obtained for water activity (aw) were in the range of 17 - 68%, which is in the range aw activity suitable for the imf material. finally according to the fair moisture content, energy consumption, and the suitable color indices of the products, the drying temperature of 65 ℃ and the belt speed of 25 mm/min at the presence of uv light can be recommended for producing intermediate moisture food from mushrooms.