A review of the drying systems and technologies in Nigeria SOBUKOLA, O.P. (Ph.D.) Federal University of Agriculture, P.M.B. 2240, Abeokuta, Nigeria sobukolaop@funaab.edu.ng

Issues in Post-harvest Losses (PHL) Inefficient harvesting and drying methods, delays in harvesting poor processing techniques inadequate method of storage and distribution, and even at the consumer end (Sanni, 1999) Corruption

The way forward is through efficient and sustainable processing methods

Drying Technology as a viable option It refers to the removal of water from materials, in most cases at temperature below boiling points (Sanni, 1999; Karim et al., 2008) It preserves foods by removing enough moisture from food to prevent decay and spoilage (Sobukola et al., 2007) Water content of properly dried food varies from 5 to 25% depending on the food.

Drying Phenomena The evaporation of moisture from the surface of the materials and The migration of moisture from the interior of a material to the surface (Sanni and Akingbala, 2000).

Sun drying system in Nigeria This is exposing the food directly to the sun Sun drying enhances the effects of the sun’s energy Drawbacks of sun drying inclement weather slow drying rates contamination of products with mycotoxins Inconsistencies in product quality Roadways sun drying Raised pole Blackened surface Dried root slices

Solar drying Technology Advantages of Solar Drying System Better Quality of Products are obtained It Reduces Losses and Better market price to the products. Products are protected against flies, rain and dust; product can be left in the dryer overnight during rain, since dryers are waterproof. Prevent fuel dependence and Reduces the environmental impact It is more efficient and cheap. Disadvantages of Solar Drying System Quality of products are not obtained in some cases. Adequate solar radiation is required. It is more expensive as it require more time for drying. (Toshniwal and Karale, 2013)

Solar cabinet dryer Direct solar dryer Indirect forced convection solar dryer Forced Convection Solar Cabinet Dryer

Drum drying Drum drying is a method used for drying out liquids from raw materials with drying drum. Pureed raw ingredients are dried at relatively low temperatures over rotating, high-capacity drums that produce sheets of drum-dried product. Some advantages of drum drying include the ability of drum dryers to dry viscous foods which cannot be easily dried with other methods. Starches, breakfast cereals, baby foods etc.

Rotary drying

Rotary drying Produces about 380 kg of fried products per 8hours Uses charcoal and electric coil as heat source Very useful for odourless fufu, garri and tapioca

Uniqueness of Flash dryer A flash dryer is a pneumatic type dryer with high temperature (150- 250°C) fuel usage (around 15 L/h) and short residence time (5 s).

Selected References Karim, O. R., Awonorin, S. O. and Sanni, L. O. 2008. Effect of pre-treatments on Quality Attributes of Air-Dehydrated Pineapple Slices. Journal of Food Technology 6 (4): 158-165. Sanni, L.O. (1999). Sanni, L. O. 1999. Effective postharvest system in Nigeria. Nigerian Food Journal, 17:61-74. Published by Nigerian Institute of Food Science and Technology (NIFST).  Sobukola, O.P., Dairo, O.U., Sanni, L.O., Odunewu, A.V. and Fafiolu, B.O. (2007). Thin layer drying process of some leafy vegetables under open sun. Food Science and Technology International 13(1): 35-40, Published by Sage Publications https://www.sagepub.com  Sanni, L. O. and Akingbala, J. O. 2000. Effects of drying methods on physicochemical and sensory qualities of fufu. Drying Technology-An International Journal, Canada, 18 (1& 2): 421-431.  Toshniwal, U. and Karale, S.R. (2013). A review on solar drying. International Journal of Engineering Research and Applications vol. 3(2), 896-902

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