Submitted to: Pacific Northwest Vegetable Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/10/2002
Publication Date: 5/6/2003
Citation: BROWN, C.R., CULLEY, D., YANG, C., NAVARRE, D.A., WROLSTAD, R., DURST, R. ANTIOXIDANT PROPERTIES IN POTATOES WITH HIGH ANTHOCYANIN CONTENT. PACIFIC NORTHWEST VEGETABLE ASSOCIATION PROCEEDINGS. P 1-3. 2003. Interpretive Summary: Potatoes are primarily known for their carbohydrate content and vitamin C. However potatoes contain phenolic compounds that can function as antioxidants. Antioxidants in the human diet have been associated with reductions in heart disease, certain cancers, and macular degeneration. Within the genetic natural variation of potato it is possible to select out flesh types that are rich in red and blue pigments which are themselves antioxidants. This study shows that the content of these pigments is related to the antioxidant level; the more color the more antioxidant activity. Although red and blue fleshed potatoes are still a rarity in the grocery store, consumers may warm up to them quickly as they make decisions to increase their consumption of antioxidants. Food processors are already producing snacks from colored potatoes, such as red potato chips. The USDA recommends that people eat four to five servings of fruits and vegetables each day, partly in order to have a sufficient intake of antioxidant compounds. Consumers will now have new options red and blue fleshed potatoes can join the ranks of leafy green vegetables like broccoli as sources of antioxidants to the diet.
Technical Abstract: Anthocyanins or pigments that are present throughout the plant kingdom. They serve as photoprotectants in leaf tissue. Many above ground parts of plants have anthocyanins which we recognize as red to blue colored organs. Fruits are usually rich in anthocyanins if they are red or blue. Potato tubers can harbor anthocyanins. We have selected potatoes that have between 10 and 40 milligrams of anthocyanin per 100 grams Fresh Weight. We performed a test of the antioxidant capacity of extracts from the tubers using the so-called Oxygen Radical Absorbance Capacity (ORAC) test. This consists of mixing the tuber extract with a fluorescing compound which loses its fluorogenic capacity as it is oxidized by a radical generating compound in the reaction mixture. The potato extract protects the fluorescing compound for a time. The ORAC is actually an under the curve of fluorescence over a two hour period, during which the fluorometer takes sixty measurements. The potato extract is calibrated against the antioxidant activity of Trolox a water soluble vitamin E analog. We found that the antioxidant values ranged from 100 to 350 micrograms of Trolox equivalents per 100grams fresh weight. The correlation was r = 0.69, which is significant. The importance of this is that we can predict how much anthocyanin is needed to achieve a target level of ORAC and this can serve as a guide in our selection program.