Impact of Storage Structures and Soil Sodicity on Vitamin C Contents of Stored Oranges

A study was carried out on the impact of storage structures and soil sodicity on vitamin C contents of stored oranges. Three 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 a bigger clay pot interspaced with clay soil of 5 cm (to form tin-in-pot, potin-pot, tin-in-wall and wall-in wall) with the outside structure wrapped with jute sack. The other two sets followed the same pattern with interspacing of 7 cm and 10 cm respectively. The set with 7 cm interspace served as the control in which the interspace soil and the jute sack were constantly wetted at intervals of between 2 to 4 hours depending on the rate of evaporation with water at room temperature. The other two sets (5 cm and 10 cm interspaced soil) were constantly wetted with salt solution (sodium chloride, NaCl) at the same interval 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 temperature and relative humidity of the storage chambers and the ambient were monitored on daily basis at 8.00am, 12 noon and 6.00pm while the vitamin C contents were determined at interval of three days for a period of three weeks. The oranges kept inside the tin-in-wall and wall-in-wall structures in all the three interspaces retained the highest amount of vitamin C at the end of the storage period. The vitamin C values of 32.42 mg/100ml, 30.68 mg/100ml, 33.98 mg/100ml and 34.94 mg/100ml were recorded for the tin-in-pot, pot-in-pot, tin-in-wall and wall-in-wall respectively for the 5 cm soil interspace. The vitamin C values of 31.78 mg/100ml, 30.80 mg/100ml, 32.94 mg/100ml and 33.32 mg/100ml were recorded for the tin-in-pot, pot-in-pot, tin-in-wall and wall-in-wall respectively for the 7 cm soil interspace while the vitamin C values of 31.54 mg/100ml, 31.16 mg/100ml, 33.42 mg/100ml and 33.54 mg/100ml were recorded for the tin-in-pot, pot-in-pot, tin-in-wall and wall-in-wall respectively for the 7 cm soil interspace. Overall, the 7 cm soil interspace structures recorded the least amount of vitamin C of 128.84 mg/100ml while the 5 cm and 10 cm soil interspace structures recorded higher values of vitamin C contents of 132.02 mg/100ml and 129.66 mg/100ml respectively.