study on drying behavior, effective moisture diffusivity and activation energy of hot air-drying of different tarkhineh formulations

the effects of a couple of factors (cooking period of wheat: 0, 1 and 3.5 h and temperature of drying 70, 80 and 90 ْc) on drying behavior of tarkhineh during hot-air drying has been investigated. tarkhineh pill samples with 8 cm diameter and 11 mm thickness were dried to 0.64(d.b). results showed that cooking of wheat led to higher water absorption of tarkhineh dough, while increased drying rate. on the other hand, increasing drying temperature resulted in higher drying rate of samples. the effects of temperature on drying rate was pronounced in raw samples compared to cooked ones, which could be attributed to the cracking in the cooked samples during drying . drying kinetics of tarkhineh in raw samples unlike cooked samples presented a falling rate period followed by a constant rate period. the effective moisture diffusion coefficient of tarkhineh varied between 1.611e-10 & 7.822e-10 (m2/s)) for the given temperature range) and corresponding activation energy was between 37.928 and 17.941(kj/mol) respectively.