Study of Chemical and Microbiological Properties of Saffron Dehydrated by using Solar Drying System

Abstract

Saffron is the most expensive spice and is highly valuable for non-oil export. Drying process is a critical control point with major effects on chemical and microbiological characteristics, so an appropriate drying method shall meet standard and market requirements as well as cost benefit. Different methods include traditional, freeze, solar, vacuum oven and microwave drying. Solar drying is performed in direct or indirect way. In the 1st way, sunlight is directly exposured with product chamber, while in the later, sun light is stored in solar collectors and then warm air flow is pumped to product chamber. Results by spectroscopy for colour agent (Crocin), odour agent (Saffranal) and flavour agent (Picrocrocin) indicated that solar drying represents high values. Moisture content taken as a key factor of dehydration was detected below permitted standard level. Microbiological profile in solar drying was in compliance with standard and in acceptable level. Optimum drying condition was achieved for 6-6.5 hours in 35-45oC. Since all microbial safety and chemical quality properties of saffron are preserved in solar drying and also considering energy saving and the resulted cost benefit of this system, it could be introduced as an appropriate drying method in producing rural and collecting sites of saffron. 

Keywords

• solar energy drying; saffron dehydration; safety; quality