Potassium and Potato Preparation

By Laura McGinnis, USDA
June 24, 2008

The preparation of a potato can have a big impact on its mineral content, Agricultural Research Service (ARS) scientists report in a new study of this popular vegetable.

Baked, roasted, boiled or fried, the potato is America's favorite vegetable. Every year, the average American eats about 130 pounds of potatoes, which are loaded with vitamins and minerals.

Cubing potatoes can reduce boiling time, but it also reduces mineral content by as much as 75 percent. That's one conclusion from a study by research geneticist Shelley Jansky and plant physiologist Paul Bethke at the ARS Vegetable Crops Research Unit in Madison, Wis.

Jansky and Bethke subjected six potato varieties to various methods of preparation, and then ran a mineral analysis for potassium and 10 other minerals. They found that cubing or shredding potatoes prior to boiling resulted in significant potassium reductions.

This could be a good cooking strategy for potato fans hoping to reduce potassium intake, such as dialysis patients. But individuals who want to get the highest nutritional bang for their buck would be better off boiling their potatoes whole.

Jansky and Bethke also examined the effects of leaching the potatoes—letting them soak in water overnight. Their results showed that leaching had no significant impact on potassium reduction, in contrast with conventional wisdom.

The results of this research could help guide the cooking decisions of people who want to reduce the mineral content of their potatoes, as well as those people who want to maximize their nutritional benefits.

ARS is a scientific research agency of the U.S. Department of Agriculture.