Modeling of Thin Layer Drying Characteristics of Banana cv. Luvhele

A. O. OMOLOLA1, A. I. O. JIDEANI1 and P. F. KAPILA2
1 Department of Food Science and Technology, South Africa
2 University of Venda, Department of Agricultural and Rural Engineering, School of Agriculture, Thohoyandou 0950, South Africa

Abstract

OMOLOLA, A. O., A. I. O. JIDEANI and P. F. KAPILA, 2015. Modeling of thin layer drying characteristics of banana cv. Luvhele. Bulg. J. Agric. Sci., 21: 342–348

Bananas (Musa spp.) are tropical fruits with high moisture and low acid content. Drying is necessary to reduce their water activity, prevent microbial spoilage, reduce weight, decreases packaging, handling and transportation costs. This study investigates the oven drying kinetics of thin layer Luvhele banana at temperature levels 40–60°C. Six mathematical drying models; Wang and Singh, Verma, Two-term, Page, Logarithmic and Two terms exponential were fitted to experimental drying data obtained from the study. The consistency of the models was determined using statistical parameters such as coefficient of determination, Mean Bias Error, Root Mean Square Error, and chi square.  Moisture migration from the banana slices was described using the Fick’s diffusion model and the effective diffusivity (ED) was calculated. The result indicated that drying took place major in the falling rate period with higher and shorter drying times achieved at a lower and higher oven temperature respectively. The ED increased with increasing oven temperatures with values in the range of 1.8 × 10-11, 1.95 × 10-11, and 2.28 × 10-11 m2/s at 40, 50, and 60°C respectively. The Two-term model gave the best results for the description of thin layer drying of Luvhele banana variety.

Key words: oven; banana (Luvhele spp.), drying kinetics, drying models, effective moisture diffusivity
Nomenclature: M0 (% wet basis) – initial moisture content of the product before commencement of the drying operation; M (% wet basis) – moisture content of the product at each moment; MR – moisture ratio); R2  – coefficient of determination; X2 – reduced chi square value; RMSE – root mean square error; MBE – mean bias error; MRexp,i – experimental moisture ratio; MRpre,i – predicted moisture ratio; n – number of constants; N – number of observations; Deff (m2/s) – effective moisture diffusivity; L (m) – half-thickness of banana slices; φ – slope; k, n, a, b, g, c – model constants; T (°C) – oven temperature; t (min) – time

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