The production of tomato paste produces huge quantities of tomato pomace as a waste product. Such a
great amount of pomacewastewould become a serious environmental problem and awaste of resources.
In this work, a study on the microwave drying of tomato pomace and the effect of osmotic dehydration
using sodium chloride was carried out for the purpose of producing dried products, which could be
used as fertilizers or animal feed. The effect of microwave power level and the NaCl concentration on
the drying rate of tomato pomace was investigated. It was found that microwave drying could be used
effectively for drying of such waste product by shortening of the drying process time. The drying rate was
found to increase with increasing microwave dosage and NaCl concentration of osmotic solution. Drying
rate constant was found to increase dramatically with increasing NaCl concentration up to about 0.1M,
and then starts to decrease steadily as the NaCl concentration further increases. The effective moisture
diffusivity varied from 1.14?10?6 to 6.09?10?6m2/s, over the output microwave power range studied.