Department of Chemical & Petroleum Engineering

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Browsing Department of Chemical & Petroleum Engineering by Subject "carrots"

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    Open Access
    Dehydration Characterization of Carrot (Daucus Carota) Slices Dried Using the Refractance Window™ Drying Technique
    (Zimbabwe Journal of Science & Technology, 2016) Akinola, A. A.; Malomo, T. O.; Ezeorah, S. N.
    The drying characteristics of yellow carrots (Daucus Carota) were studied using a laboratory scale batch Refractance Window™ (RW) dryer. This study was performed to facilitate the understanding of the design on a continuously operating RW dryer, by studying the drying characteristics of a batch RW drying process. A dryer was constructed by modifying a laboratory water bath. The bath is covered with a transparent Polyethylene terephthalate (PET) plastic film that has a drying area of 10 cm by 10 cm. 3 mm thick slices of carrots were dried on the Refractance WindowTMdryer, and the variation of the moisture content of the slices was measured during the drying process. The water temperature beneath the plastic film was maintained at 60 oC. From the experimental data the drying curves, the drying rate curves and the Krischer curves were plotted. The thin layer mathematical drying model that describes the drying kinetics of the drying data was determined. The bulk density of the powdered carrots and the variation of the rehydration ratio of the carrot slices with time was determined. The effective moisture diffusivity of the carrots is also estimated. Observations indicate that the carrot slices dried to below 10% moisture content on a dry basis in about 200 minutes. Regression analysis suggests that the Haghi and Ghanadzadeh model best describes the drying behaviour for the 3 mm thick slices with a coefficient of determination (R2) value of 0.999 for the 17 models studied. The Rehydration Ratio of the carrot samples varied from 2.457 to 4.126 with rehydration times of 10 to 60 minutes. An average bulk density value of the carrot powder samples was 0.8625 grams/ml. The effective moisture diffusivity of the 3 mm thick carrot slices was determined to be 7.29513×10-8 m2/s.