EFFECT OF DIFFERENT DRYING METHODS ON THE DRYING KINETICS AND PROXIMATE COMPOSITION OF GARDEN EGG

Garden egg (Solanum aethiopicum L.) is a perishable crop as a result of high moisture content which necessitates its conversion to a shelf-stable product using appropriate preservation techniques such as drying. Therefore, this study evaluated the effect of drying methods on the drying kinetics of dried garden egg slices. The garden eggs were washed, sorted, and cut transversely into slices (3.0, 6.0 and 9.0 mm) and dried using the sun, solar and cabinet (60 ºC) drying. Drying kinetic, effective moisture diffusivity and the activation energy were determined. Proximate composition (moisture content, crude protein, crude fiber, crude fat and ash) was determined for both dried and fresh samples. Drying took place entirely in the falling rate period. Effective moisture diffusivity (Deff) increased with an increase in slice thickness. Effective moisture diffusivity varied from 3.641 10-10 to 1.062 10-9 for sun drying, 2.46710-10 to 1.08310-9 for solar drying and 2.48710-10 to 1.21310-9 for cabinet drying. The activation energy for cabinet drying was 14.93, 17.01 and 19.55 kJmol-1 for slice thicknesses of 3.0, 6.0 and 9.0 mm, respectively. The moisture content ranged from 4.02 to 8.02% for all analyzed samples, crude protein (17.5 - 20.13%), crude fibre (12.01 - 20.02%), crude fat (2.00 - 2.03%) and ash content (4.01 - 6.03%). The moisture content and ash content of sun-dried samples were higher compared to solar and cabinet-dried samples. The crude protein content, crude fiber content and crude fat content of solar-dried samples were higher compared to sun and cabinet dried samples. In conclusion, this study has shown that garden eggs subjected to solar drying and cabinet drying (at 60℃) gave a better result in terms of moisture content, crude protein, crude fibre, crude fat and ash content. Samples with lower slice thickness and higher temperature dry faster. Deff increases with an increase in slice thicknesses.