Thin Layer Modelling of Indirect and Mixed-Mode on-Farm Drying of Selected Vegetables
Nathaniel Oji
Department of Agricultural and Bio-Environmental Engineering, Federal Polytechnic Kaduna (Kadpoly), Nigeria.
S. A. Okaiyeto
Department of Agricultural and Bio-Environmental Engineering, Federal Polytechnic Kaduna (Kadpoly), Nigeria.
Y. A. Unguwanrimi
Department of Crop Science, Faculty of Agriculture, Kaduna State University, (KASU), Kaduna Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The thin layer drying characteristics of tomato and okra slices dried using mixed-mode on-farm solar dryer, indirect mode on-farm solar dryer and open sun drying. The tomato and okra slices dried faster when dried under the mixed-mode on-farm solar dryer. Drying time was reduced considerably using the on-farm solar dryers. The drying data were fitted into Lewis, Henderson and Pabis, and page equations. The Page model (R2=0.9365, 0.9623; X2= 0.0067, 0.0000579; RMSE= 0.0086, 0.0020 and MBE= -0.008, -0.002) gave the best prediction for the mixed-mode drying and indirect mode drying of tomato slices respectively. In the same vein Page model (R2=0.9202, 0.933o; X2= 0.00091, 0.000730; RMSE= 0.0265, 0.0244 and MBE= -0.0088, -0.0074) gave the best prediction for the mixed-mode drying and indirect mode drying of okra slices respectively. Effective moisture diffusivity of tomato slices varied between -7.4724 X 10-08 and -1.6439 X 10-07 while that of okra varied between -3.12 X 10-07 and -8.08 X 10-07. The indirect mode dryer gave the best quality of dried tomato and okra.
Keywords: Drying, Characteristics, Tomato, Okra, mixed mode dryer, indirect mode dryer