|Yang, Ching Pa|
|Brown, Charles - Chuck|
Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2003
Publication Date: 3/1/2004
Citation: Culley, D., Yang, C., Bonierbale, M., Brown, C.R. 2004. Determining the lipid-soluble antioxidant capacity of pigmented tubers: application in assessing the antioxidant potential of potato germplasm. American Journal of Potato Research. 81:51.
Technical Abstract: In recent years, much attention has focused on the importance of dietary antioxidants in preventing heart disease and some types of cancer. Potato is already a rich source of vitamin C, one of the more famous antioxidants, but in most modern cultivars the levels of many other potential antioxidant compounds, (e.g. anthocyanins and carotenoids) is limited. Fortunately, potato germplasm collections provide a rich source of material to improve the antioxidant content of tubers. Direct measurement of these compounds is one method of selecting for increased antioxidant capacity, but this approach has several inherent limitations: 1) Determining the concentration of these compounds is often difficult and expensive; 2) Only those compounds being assayed for are considered in selections; and 3) The levels of these compounds provides only an indirect measure of the antioxidant capacity of tubers. A direct measure of the ability of the tuber to absorb reactive oxygen species, (i.e. the useful antioxidant capacity of tubers), is provided by the ORAC (Oxygen Radical Absorption Capacity) assay. This assay measures the ability of tuber extracts to protect a target molecule from reactive oxygen and, while it is relatively straightforward for water-soluble antioxidants, has been difficult to apply to lipid-soluble antioxidants such as carotenoids and vitamin E. To address this problem, we have modified existing protocols to allow the use of a microplate fluorometer to perform relatively high throughput assays of the antioxidant capacity of the lipid-soluble fraction of tuber extracts. We will describe the development of the lipid ORAC assay, and show results from some determinations of the antioxidant capacity of pigmented potatoes.