The Impacts of Fluidized and Static Bed Drying Methods on Bio-active Compounds and Antioxidant Properties of Saffron Petal

Abstract

Saffron petal was dried from 85% to 10% moisture content with fixed layer bed (FLB), semi fluidized bed (SFB) and fully fluidized bed (FFB) at temperatures (t) of 35, 45 and 55°C. The airflow (v) of FLB, SFB and FFB were 0.2, 0.7 and 1.7 ms-1, respectively. When the t/v ratio increased in each method, the dehydration time decreased considerably. The dehydration times and drying rates of saffron petal for FLB (v = 0.2 ms-1& t = 35oC) and FFB (v = 1.7 ms-1& t = 55oC) were “570 & 30 min” and “0.13 & 2.50 gH2O/min”, respectively. When the airflow increased from 0.2 to 0.7 and then to 1.7 ms-1, the phenolic, anthocyanin & antioxidant contents of dried saffron petal improved to about 6, 15 & 15% and then to 15, 20 & 42%, respectively. However, by increasing air temperature from 35 to 45°, their phenolic and anthocyanin contents did not change significantly. However, sharp reductions of 20, 23 and 41% respectively were noticed in phenolic and anthocyanin contents and antioxidant activities of saffron petal when the drying temperature exceeded 45 and reached to 55oC. Overall, the fresh saffron petal dehydrated at 45oC with FFB had the highest phenolic and anthocyanin contents and antioxidant activities.