One hundred grams of fresh weight from each vegetable; Chinese white vegetable, tomato, cucumber, pumpkin, pea eggplant, carrot, cabbage, morning glory, Chinese broccoli and yard long bean, as well as from each fruit; rose apple, pineapple, papaya, water melon, apple, cantaloupe, mango, jackfruit, orange and pomelo were homogenized with 10 ml of distilled water, filtered by whatman No.1 paper and stored at 4 ̊C unit use. The pH of crude extracts and filtrate from each fruit and vegetable was measured with pH paper.