(1) Vitamin C also known as ascorbic acid, is the enolic form of 3-oxo-L-gulofuranolactone.
Humans cannot synthesize it because the enzyme that catalyzes the synthesis (L-gluconolactone oxidase) is defective in humans.
(2)All fruits and vegetables contain some amount of vitamin C. Foods that tend to be the highest sources of vitamin C include green peppers, citrus fruits and juices, strawberries, tomatoes, broccoli, turnip greens and other leafy greens, sweet and white potatoes, and cantaloupe. Vegetables such as broccoli, sweet green and red peppers, potatoes (with skin), tomatoes, and Brussels sprouts are good sources. Cabbage and many dark green leafy vegetables are all good sources of vitamin C. Other excellent sources include papaya, mango, watermelon, brussels sprouts, cauliflower, cabbage, winter squash, red peppers, raspberries, blueberries, cranberries, and pineapples. Raw and cooked leafy greens (turnip greens, spinach), red and green peppers, canned and fresh tomatoes, potatoes, winter squash, raspberries, blueberries, cranberries and pineapple are also rich sources of Vitamin C. Ascorbic acid is a relatively fragile molecule and it may be lost from foods during preparation, cooking, and/or storage. Ascorbic acid is easily destroyed by oxidation, particularly in the presence of heat and alkalinity, and because it is highly soluble in water, it is often discarded in cooking water. Although the vitamin occurs in small amounts in animal tissues, it is usually destroyed either by exposure to air or by processing before it reaches the table.
Structure of Vitamin C is shown on site below.
http://www.chm.bris.ac.uk/webprojects2002/schnepp/vitaminc.html |
