MATHEMATICAL MODELING AND EXPERIMENTAL STUDY ON THIN LAYER HALOGEN DRYER OF STRAWBERRY AND STUDY ITâS EFFECT ON ANTIOXIDANT ACTIVITY

Al-Hilphy Al-Hilphy

doi:10.3844/ajabssp.2013.268.281

Abstract

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.

Highlights

Strawberries are popular fruits grown in Iraq and many other countries
The summery of models parameters of nine thin layer drying models that were used for expressing drying characteristics of strawberries sliced dried by halogen dryer at different drying temperatures and the statistical evaluation of models using three different criteria (R2, x2 and Root Mean Square Error analysis (RMSE)) are presented in the Table 2
R2, x2 and RMSE values were changed between 0.8965 and 0.9995, 0.0147 and 6.166, 0.0987 and 2.0275 respectively. It observed that the page model satisfactorily described the drying kinetic of strawberry slices dried under 60°C

Summary

Introduction

Strawberries are popular fruits grown in Iraq and many other countries. Strawberries could be consumed fresh or in many others forms, such as juice, concentrate jam, jelly, dried rehydrated with yogurt, bakery products, alcoholic beverage and marmalades (Pallauf et al, 2008). Strawberries have been used in the Spain and Morocco as a traditional medicine (Tahraoui et al, 2007). Natural sun drying is the most common method used to preserve agriculture products in most tropical and sub tropical countries. Natural sun drying isn’t possible as a drying method for the Strawberries, because this fruit appears in clusters and ripen in autumn and winter months. On the other hand natural sun drying application is restricted by the long drying time and need to for favorable weather (Arora, 2006)

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Conclusion