Optimization of solar drying process parameters of cooking banana using response surface methodology

Abstract

The drying process parameters of cooking banana dried on an active indirect mode solar dryer were optimized using Response Surface Methodology. The independent factors considered were the air inlet area of an active indirect mode solar dryer and slice thickness of the product. Five levels of the air inlet area for four shapes [(Square – 4, 16, 36, 64 and 100 cm2), (Rectangular – 8, 24, 48, 80 and 96 cm2), (Circular – 3.142, 12.568, 28.278, 50.272 and 78.55 cm2) and (Triangular – 8, 16, 24, 32, 40 cm2)] and five levels of slice thicknesses of 4, 8, 12, 16 and 20 mm were considered. The desired responses were moisture content, drying rate, and drying efficiency. Experimental data from the field gave a moisture content range of 12.05 to 12.20 % (wet basis) and a drying rate range of 1.95 to 3.99 g/hr, while the drying efficiency was between 13.85 to 31.84 %. The optimum responses obtained were: 11.98 % (moisture content); 4.85 g/hr (drying rate); and 34.51 % (drying efficiency). The corresponding optimal conditions were: 40 cm2 (triangular air inlet) and 20 mm (slice thickness); 100 cm2 (square air inlet) and 20 mm (slice thickness); and 100 cm2 (square air inlet) and 20 mm (slice thickness). The experiment was repeated at the optimal conditions, and a deviation of less than 5% was observed. The square air inlet area of 100 cm2 and slice thickness of 20 mm was recommended for optimal drying of cooking banana using an active indirect mode solar dryer.