Comparison of the Effects of Drying Processes: Vacuum Oven, Freeze, Solar and Microwave with Traditional Method on the Qualitative Characteristics of the Iranian Saffron

Saffron, the world’s most expensive condiment, is one of Iran’s most important non-petroleum exports. The drying method is determinant of saffron quality and price in the world market. So, the aim of this study was the comparison of the effects of saffron dehydration methods, like vacuum oven, freeze, microwave and solar drying with traditional method. During this experimental study and for production of saffron flowers, one of the farms in Gonabad was selected randomly and the flowers were picked and mixed thoroughly, together. The morphological specifications, percentage of yield of the stigmas, chemical test (moisture, ash, total nitrogen &, acid insoluble ash) were determined. Stigmas were dried. After dehydration the moisture content, total ash, acid insoluble ash, water soluble extract, total nitrogen, crude fiber, crocin, picrocrocin, saffranal and sensory specifications (color, texture and odor) were determined. The results of chemical analysis indicated that the solar dried, vacuum oven dried and Pejuhandeh Vol.13, No 63, 2008 7 microwave dried samples had preferable colour (crocine)outcomes. However, from aromatic point of view (saffranal) traditional sample had significant preference (P<0.05). The amount of the picrocrocin (taste compounds) in samples did not have significant differences within each other. The results of sensory analysis indicated that, color of dried samples by solar, freeze and microwave methods, soluble color of dried samples by solar, freeze and vacuum oven had significant differences (P<0.05) that other methods. The results of the microbiological test of all dried samples were in Iranian standard levels except the traditional and freeze dried samples. Although the samples of four methods of drying were of high quality compared to the traditional samples, the solar drying method can be reasonably applied in rural area as suggested method of drying.