Effect of gamma irradiation on surface shrinkage and rehydration ratio during drying of mushroom (Agaricus bisporus)

The final quality of drying product should be considered as one of the most important indicators in the drying process.In this research, the effects of gamma irradiation doses (0, 1.2, 2.4 and 3.6 kGy), drying temperature (50, 60 and 70°C) and slice thickness of mushrooms (3 and 5 mm) on the surface shrinkage and rehydration ratiowere studied.Thin-layer dryer based on machine vision was used for the experiment.The results showed that the simple and intraction effects of the factorson the surface shrinkage and rehydration ratio weresignificant(P<0.01)in most cases.By increasing irradiation dose, shrinkage slightly increased, and rehydration ratio in dried samples were increased. Also,the maximum rehydration ratiowas 3.43g/gin dose of 3.6 kGy anddryingtemperature of 60°C in the thickness of 3 mm.Finally, shrinkage increased by increasing drying temperature and decreasing slicethickness of mushroom.So that the minimum and maximum values of surface shrinkagewere 0.461 and 0.667, respectively.