Determination of ascorbic acid levels in oranges under different storage conditions using Redox Iodometric method

Abstract

Ascorbic acid is one of the most important vitamins to the human body due to its potentially protective role as an antioxidant. Oranges by far the most important citrus species are an excellent source of ascorbic acid. The ascorbic acid in three varieties of Ghanaian local oranges was estimated after storage under four different storage conditions. The storage conditions were deep freezing, dark cupboard, open shelf and in the sun. The redox titrimetric method using potassium iodide as the titrant and starch as an indicator was employed to evaluate the ascorbic acid levels in the orange samples after two, four and six days. The result shows a decrease in the ascorbic acid content of oranges over the storage periods. The decrease was expressed as a percentage loss of ascorbic acid originally in oranges. Less ascorbic acid was lost with the refrigerated orange samples compared to the other storage conditions. A huge loss of ascorbic acid was however lost with the samples that were exposed to the sun.