Current Trends in Technology and Sciences Volume : 1, Issue : 1 (May-June-2012) Copyright © 2012 CTTS.IN, All right reserved 22 Impact of Soil Inter-space Bulk Density and Moisture Content on Vitamin A Content of Stored Oranges in Passive Evaporative Cooling Structures Sunmonu, M. O. Department of Agricultural & Biosystems Engineering, University of Ilorin, Nigeria, sholams2000@yahoo.co.uk Chukwu, O. Department of Agricultural & Bioresources Engineering, Federal University of Technology, PMB 65, Minna, Nigeria. Alabadan, A. B. Department of Agricultural & Bioresources Engineering, Federal University of Technology, PMB 65, Minna, Nigeria. Osunde, Z. D. Department of Agricultural & Bioresources Engineering, Federal University of Technology, PMB 65, Minna, Nigeria. Abstract - A study was conducted on the impact of soil inter-space bulk density and moisture content on the vitamin A content of stored oranges in passive evaporative cooling structures. Two sets of four different types of passive evaporative cooling structures made of two different materials, clay and aluminium were constructed. One set consists of four separate cooling chambers. Two cooling chambers were made with aluminium container (round and rectangular shapes) and the other two were made of clay container (round and rectangular). These four containers were separately inserted inside bigger clay pots and lateritic walls inter- spaced with clay soil of 5 cm (to form tin-in-pot, pot-in-pot, tin-in-wall and wall-in wall) with the outside structure wrapped with jute sack. The other set followed the same pattern with interspacing of 10 cm. The two sets (5 cm and 10 cm interspaced soil) were constantly wetted with salt solution (sodium chloride, NaCl)) at intervals of between 2 to 4 hours depending on the rate of evaporation to keep the soil in moist condition. In addition, the control has no fans and the inner cooling chambers were not lined with polyethylene nylon while the other two sets have fans and their inner cooling chambers lined with polyethylene nylon Freshly harvested oranges were used for the experiment and the inter-space soil bulk density, soil moisture content and vitamin A content of stored oranges were determined at interval of three days for a period of three weeks. The interspace soil bulk density values of 0.98 g/cm 3 , 1.6 g/cm 3 , 0.91 g/cm 3 , 0.98 g/cm 3 , 0.99 g/cm 3 , 0.97 g/cm 3 and 0.92 g/cm 3 with the soil moisture contents values of 78.4%, 81.58%, 82.56%, 79.12%, 79.68%, 79.74% and 79.74% were recorded for the 5 cm structures. Also the interspace soil bulk density values of 1.42 g/cm 3 , 1.21 g/cm 3 , 1.34 g/cm 3 , 1.00 g/cm 3 , 0.98 g/cm 3 , 0.98 g/cm 3 and 0.97 g/cm 3 with the soil moisture contents values of 78.73%, 79.17%, 78.18%, 78.34%, 82.54%, 81.79% and 81.36% were recorded for the 10 cm structures. Keywords - Bulk Density, Vitamin A, Soil, Cooling, Evaporation. 1. INTRODUCTION Fruits and vegetables are of good importance to human health. They contain antioxidants, minerals and phytochemicals in their correct combination that help keep the blood sugar in balance, create energy in the body and build up the immune system (Ray, 2011). An orange, specifically sweet orange (Citrus sinensis), is the most commonly grown fruit in the world (Morton, 1987). Common oranges (also called “white”, “round or “blond” oranges) make up two-thirds of all oranges grown and are used primarily to produce juice (Kimball and Dan, 1999). The abundance of antioxidants, vitamins, fibre and phytonutrients in orange foods are good for the skin, eyes and heart, and they may also decrease the risk of cancer and lower high blood pressure. In recent research studies, the healing properties of oranges have been associated with a wide variety of phytonutrient compounds. An orange has over 170 different phytonutrients and more than 60 flavonoids, many of which have been shown to have anti-inflammatory, anti- tumour and blood clot inhibiting properties, as well as strong antioxidant effects. ( Yuan et al., 2003; Stange et al., 1993; Wood, 1988; Rapisarda et al., 1999; Pattison et al., 2004 and Cho et al., 2004). Vitamin A is present in fruits and can be stored by the body in large quantities. Oyenuga (1968) reported values of Vitamin A as 200 IU for guava, 190 IU for sweet orange, 420 IU for tangerine and 590 IU for water melon. Vitamin A deficiency results in xerophtalmia- characterized by dry corneal membranes. Its deficiency also brings about a malfunction in the visual purple and the consequent night blindness. Vitamin A is important for night vision, as an antioxidant can neutralize the