INFLUENCE OF DRYING AIR TEMPERATURE, AIR VELOCITY AND SURFACE LOAD ON DRYING KINETICS AND COLOR OF JEW'S MALLOW LEAVES | ||||
| Journal of Food and Dairy Sciences | ||||
| Article 3, Volume 3, Issue 7, July 2012, Page 401-416 PDF (747.07 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jfds.2012.77721 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
K. Youssef  ; H. E. Embaby
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| Food Technology Department, Faculty of Agriculture, Suez Canal University, 41522 Ismailia, Egypt | ||||
| Abstract | ||||
| The effect of drying air variables including: temperature (50, 60 and 70 ºC), velocity (0.2, 0.4 and 0.6 m/s) and surface load (125 – 500 g/ 0.22 m2) on the drying kinetics and color of Jew's mallow leaves under hot – air drying was determined. All studied variables affected the drying time. Seven drying models were fitted to drying data and evaluated by using the coefficient of determination (R2). The Thomson and modified Page models showed a better fit to experimental data as compared to other models. In the ranges studied, the obtained values of the effective moisture diffusivity (Deff) ranged from 3.9167 x 10-11 to 9.3118 x 10-11 m2/s for Jew's mallow leaves calculated using the Fick's diffusion model. Using Deff, the activation energy (Ea) was determined assuming the Arrhenius – type temperature relationship and was found to be 35.01 KJ/ mol. From the results of color quality, drying at 60 ºC, 0.4 m/s and surface load of 250 g/ 0.22 m2 (i.e. about 1200g/ m2) were found to be the optimum conditions for drying Jew's mallow leaves. | ||||
| Keywords | ||||
| Jew's mallow; Drying models; Effective moisture diffusivity; Activation energy; Color quality | ||||
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