Effect of Farm Product Intrinsic Properties on Convective Drying: Case of Okra

In this study, the material is okra, a cucurbitaceous largely consumed in West Africa and South Asia. The influence of the external air parameters on food drying with different size, maturity, shape of the material is considered by convective drying. So, the okra was cut in several parts according to its three characteristic zones, the basis, the middle of the okra and the extremity because the three parts of the vegetable have not the same resistances in transfers by convective drying. The maturity of the okra also has an influence. The okra dries faster in its younger or older age. Okra dries slowly when its maturity is convenient to be consumed. The drying duration of okra with the age of 1, 2, 3, 4 and 5 days is respectively 580, 780, 990, 1200 and 850 min. When we consider the three (matters) constituent of the okra: the skin, the seeds and the central material, the central matter dries faster. The diffusion coefficient was identified in all cases in order to compare the influence of those intrinsic properties of that food.

What Process Optimizes Convective Drying of Farm Products with Complex Constitution:Case of Okra(Abelmoschus esculentus)

In this paper, we propose an optimized process for farm product convective drying. Above and beyond the influence of the air parameters on foodstuff convective drying, this work shows that product internal parameters and drying proceedings must be taken into account during the evaluation of their convective drying. Results indicate that okra maturity influences its convective drying. It dries faster when it is too young or when it is advanced age. Drying time of okra of 1, 2, 3, 4 and 5 days old is respectively 580 min, 780 min, 990 min, 1200 min and 850 min. Also, one observes that considering okra on its three zones according it length, i.e. its base, middle and extremity parts have not the same resistance to transfers during convective drying. These three zones have respectively 400 min, 520 min and 600 min of drying time. Okra cut reveals a major importance on its convective drying evaluation. The longitudinal cut di-viding okra on four parts, sliced with 5 mm and 10 mm of thickness and the whole okra put respectively 150 min, 200 min, 280 min and 400 min for their drying. At last, three (03) different constituents of okra, namely, the skin, the seeds and central material behave differently during convective drying. The drying time of the central material, the seeds and the skin is about 70 min, 150 min and 190 min respectively, against 400 min for the whole okra.

Statistical Study of foF2 Diurnal Variation at Dakar Station from 1971 to 1996:Effect of Geomagnetic Classes of Activity on Seasonal Variation at Solar Minimum and Maximum

The statistical study of F2 layer critical frequency at Dakar station from 1971 to 1996 is carried out. This paper shows foF2 statistical diurnal for all geomagnetic activities and all seasons and that during solar maximum and minimum phases. It emerges that foF2 diurnal variation graphs at Dakar station exhibits the different types of foF2 profiles in African EIA regions. The type of profile depends on solar activity, season and solar phase. During solar minimum and under quiet time condition, data show?the signature of a strength electrojet that is coupled with intense counter electrojet in the afternoon. Under disturbed conditions,?mean intense electrojet is observed in winter?during fluctuating and recurrent activities. Intense counter electrojet is seen under fluctuating and shock activities in all seasons coupled with strength electrojet in autumn. In summer?and spring under all geomagnetic activity condition, there is intense counter electrojet. During solar maximum, in summer and spring there is no electrojet under geomagnetic activity conditions.?Winter shows a mean intense electrojet. Winter and autumn are marked by the signature of the reversal electric field.