Drying Characteristics and Kinetics of Okra at Different Thickness

Abstract

The effect of sample thickness and temperature on the drying characteristics of okra was investigated using a laboratory moisture analyser (Denver instrument IR-30) at sample thickness of 5mm, 10mm and 15mm and temperatures of 90 o C, 100 o C and 110 o C respectively. The experimental data was fitted into three thin layer mathematical models. The fitness of the experimental data were evaluated using statistical analysis. It was observed that data fitted well with the Page model for the temperatures and sample thicknesses with the highest R2 values of (0.9904, 0.9962, 0.9963); (0.9963. 0.0072, 0.9937); (0.9924, 0.9940, 0.9933) for 5mm-. 15mm thickness at 90oC, 100 o C and 110 o C respectively with the lowest χ2, MBE and RMSE values. Therefore, Page models adequately described the drying characteristics of okra investigated. The effective moisture ratios were observed to increase with temperature and decrease with okra thickness. The activation energies obtained from Arrhenius equation for 5mm, 10mm and 15mm were 108.7KJ/mol, 118.7KJ/mol and 97.8KJ/mol respectively. Contribution/Originality:This study documents the characteristics and kinetics of okra with effect of thickness. INTRODUCTIONAgricultural products such as fresh fruits and vegetables are perishable [1] and difficult to preserve due to their high moisture content and tender texture. This leads to post harvest losses due to deterioration. Also, transportation of such fruits from one place to the other can be cumbersome due to the weight and volume they can occupy. Drying is the most common preservation method for such products [2]. Up till now, a lot of food losses are being experienced due to inadequate preservation, storage and processing techniques The production of okra in Nigeria is seasonal and often times, the fruits get rotten and become wasted as there are no adequate preservation methods especially at the peak production season where large quantities are produced.Okra is highly nutritious and contains several important micronutrients minerals that the body need [3,4]. Okra also contains some elements that are essential for the treatment of certain disease conditions in humans [5].Although the delicacy of okra is in the fresh fruit and it is mostly used fresh to prepare soup, the shelf life is short [4] and cannot be preserved for longer period. Drying of okra is necessary in order to reduce the water content to a reasonable level so as to prevent the growth and production of microorganisms that facilitate deterioration reaction.Drying will also preserve okra for longer period of time and to make it available and affordable at off season [6]. Furthermore removal of moisture through drying will increase the concentration of the nutrients [7,8].

Effect of slice thickness and hot-air temperature on the kinetics of hot-air drying of Crabapple slices

“…Besides, at a constant drying temperature, D eff values increase with thickness. Torubeli et al (2021) studies of the drying kinetics of okra at various thicknesses have shown that values at all temperatures of 5mm are higher than values at 10mm and 15mm. This is because diffusion channels are smaller in larger samples and moisture is more readily migrated, resulting in greater D eff (Deng et al, 2018).…”