The effect of natural and artificial fruit ripening agents on the pH of selected fruits has being analysed in Port Harcourt, Nigeria. The pH of orange (Citrus x sinensis), tomato (Solanum lycopersicum L.), lime (Citrus x aurantifolia), pineapple (Ananas comosus), grape fruit (Citrus x paradisi), banana (Musa acuminata), tangerine (Citrus reticulata) and lemon (Citrus x limon L.) was determined by artificially ripening the selected fruits. The fruits were properly washed with water and kept in an air-tight jute bag with 10g of calcium carbide which was not allowed to have direct contact with the fruits for 48hrs at 34+ 80C, to soften the fruits. Thereafter, water was sprinkled on the fruits at regular intervals for 22hours at 32+80C in order to maintain low temperature and to de-green the fruits. A pH stripe was used to test the pH values of unripe banana and tomato, then marched with a pH colour chart and their pH values were both 3. Also, 5 drops of universal pH indicator was mixed with 50ml of unripe orange, tangerine, lime, lemon, pineapple, and grape juices each and the pH values were 3, 3, 2, 2, 3, and 2.3 respectively. 5drops of universal pH indicator was also used to test 50ml of the naturally and artificially ripened tomato, lime, pineapple, orange, banana, lemon, grape and tangerine juices each and their pH values were 4,3,3.7,3.7,3.7,3,3,4 and 4,2.7,4.3,4.7,4.3,3,3.7,3.7 respectively. The results of pH test showed that the pH value of each fruit increased when ripened naturally and artificially. It is therefore recommended that fruits should be eaten only when ripe, to avoid consumption of organic acids which are related to unripe fruits.
