Vitamin C is an essential nutrient in the diet, but is easily reduced or destroyed by exposure to heat and oxygen during processing, packaging, and storage of food; particularly when Vitamin C containing raw material (citrus fruits) undergoes thermal processing like pasterization and sterilization during juice production. The instability of Vitamin C makes it more difficult to ensure an accurate listing of Vitamin C content on the nutrition label. To understand the trend of stability of Vitamin C during processing/storage, the monitoring of Vitamin C concentration at various processing temperatures is important. Here, in this experiment the concentration of Vitamin C at after treating/heating at 60°C, 75°C and 90°C. The official method of analysis for Vitamin C determination of juices used here is the 2, 6-dichloroindophenol titrimetric method. The principle behind the method is, ascorbic acid reduces the indicator dye to a colorless solution. At the endpoint of titrating an ascorbic acid containing sample with dye, excess unreduced dye is a rose-pink color in the acid solution. The titre value of the dye can be determined using a standard ascorbic acid solution. Food samples in solution then can be titrated with the dye, and the volume for the titration used to calculate the ascorbic acid content in samples treated at three different temperatures.