MATHEMATICAL MODELING AND EXPERIMENTAL STUDY ON THIN LAYER HALOGEN DRYER OF STRAWBERRY AND STUDY IT’S EFFECT ON ANTIOXIDANT ACTIVITY

The halogen drying characteristics of strawberry (Fragaria ananassa Duch) slices were investigated. Drying experiments were carried out a three different drying temperatures (60, 70 and 80°C). The effect of drying temperature on the drying rate, drying coefficient, efficiency, effective diffusivity of the strawberry and antioxidant activity were evaluated. The best model for describing the halogen drying process was chosen by fitting nine commonly used drying models. The effective moisture diffusivity and activation energy were calculated using an infinite series solution of Fick’s diffusion equation. The results showed that increasing drying temperature accelerate the halogen drying process. As well as, increasing of drying rate, drying rate constant, drying coefficient and effective diffusivity. All drying experiments had only falling rate period. The goodness of fit tests indicated that the proposed modified page model gave the best fit to experimental results at 70 and 80°C, but page model gave the best fit to experiment results at temperature of 60°C. The effective diffusivity varied from 7.53×10^-9 -2.52×10^-8 m²/sec. Effective diffusivity was satisfactorily by an Arrhenius type relationship with activation energy with in 60-80°C temperature range. The ability of reducing power of the ferrous ion can taken as an indicator for the ability or antioxidant power for strawberry extracted.