Optimizing The Application of SO2 in Apricot Drying

To optimize the use of sulfur in drying of apricot, four following treatments including: sulfiting and drying, sulfiting- blanching and drying, blanching- sulfiting and drying, and finally sulfiting- drying to % 50 of initial moisture- blanching and finish drying were studied. The levels of sulfur addition were from 0 to 1500 ppm, SO2 and drying was carried out at 50 to 74 °C. The quality of dried apricots was judged by extent of browning development and hardness determination. A response surface statistical design was applied to evaluate the quality of slabs and to determine optimum drying conditions. The results showed that sulfite was the major factor in controlling dried apricot quality. At present of sulfur, the role of temperature can be neglected. The amount of used sulfite has no significant effect on drying time of apricots. Blanching reduced drying time of product significantly. By increasing the drying temperature, loss percentage of SO2 was reduced for all treatments. Blanching and then sulfiting, increased loss in residual sulfur of products significantly. Application of sulfiting– drying method, using 900 ppm of SO2 at 50 to 68 °C was found to be the best treatment because of production of slabs whit average hardness and color texture equal to 1.44 N/m2 and 0.07 Od respectively.