Impact of gamma-irradiation on some mass transfer driven operations in food processing

The effect of gamma-irradiation pretreatment on some mass transfer driven operations such as dehydration, osmotic dehydration and rehydration, commonly used in food processing, was studied. Applied irradiation up to 12.0 kGy resulted in decrease in hardness of the samples, as indicated by texture analysis. The effective diffusion coefficients of water and solute determined for dehydration, osmotic dehydration as well as for rehydration using a Fickian diffusion model. The effective diffusion coefficients for water (in case of osmotic dehydration and dehydration) and solid diffusion (in case of osmotic dehydration) were found to increase exponentially with doses of gamma-irradiation (G) according to an equation of the form D=A exp(−B/G), where A and B are constants. Microstructures of irradiated-carrot samples revealed that the exposure of carrot to gamma irradiation resulted in the breakage of cell wall structure, thereby causing softening of irradiated samples and facilitating mass transfer during dehydration and osmotic dehydration. The rehydration characteristics showed that gamma-irradiated sample did not absorb as much water as control, probably due to loss of cell integrity.