EFFECT OF HEAT ON ASCORBIC ACID CONTENT OF SOME LOCALLY SOURCED FRUITS (MANGO, TANGERINE, LEMON AND GRAPE)

Ascorbic acid plays a critical role in various metabolic activities such as the absorption of iron from nonheme products and negates the formation of reactive oxygen, a major product responsible for oxidative stress and recent studies has shown that it is thermally labile. The effect of heat on its content in fruit juices has been successfully investigated. Fresh fruit samples were obtained from New Benin market and the juice extracts were obtained using mechanical press after which temperatures of 40,
60, 80, and 100°C were applied and the ascorbic acid contents of the fresh juice extracts and after treatment were determined using iodimetry at interval of 24 hours for five days. From the results obtained, the ascorbic acid content was found highest for
mango juice extract with a value of 11.40mg. The values obtained for grape, lemon, and tangerine are 10.42, 5.86, and 4.98mg respectively. From the values, it was obvious that heating played a major role in the ascorbic acid content of the extracts. This was demonstrated by plotting the contents in mg as functions of time from where it was seen that Lemon fruit juice had the highest correlation coefficient of 0.9918 at 60°C while the least was found for grape fruit juice at 40 and 80°C with a value of 0.9205.