Combined Effect of Drying Time and Slice Thickness on the Solar Drying of Okra

Abstract

The effect of slice thickness and drying time on colour, viscosity, microbial load, moisture, crude fibre, vitamin C and ash contents of okra (Hibiscus esculentus) during solar drying was studied using three slice thicknesses (5.0 mm, 10.0 mm, 15.0 mm) obtained from a survey and five drying times (0, 24, 48, 72 and 96 h). The results showed that slice thickness had a significant effect (P < 0.01) on moisture, crude fibre and ash contents but not on vitamin C content, viscosity, colour and microbial load. However, the effect of drying time was highly significant (P < 0.01) on all the parameters determined. The combined effects of slice thickness and drying time were observed to be highly significant (P< 0.05) on ash, crude fibre and moisture contents, viscosity and microbial load but had no significant effect (P < 0.05) on colour and vitamin C content. There was a strong correlation between moisture content and ash (R = - 0.926), crude fibre (R = - 0.94), vitamin C contents (R = 0.928) and viscosity (R = - 0.963) in all samples during drying. The study showed that a slice thickness of 10.0 mm and a drying time of 48 h was suitable for the solar drying of okra.