Elsevier

Journal of Renal Nutrition

Volume 18, Issue 6, November 2008, Pages 530-534
Journal of Renal Nutrition

Original Research
Changes in Potassium Content of Different Potato Varieties After Cooking

https://doi.org/10.1053/j.jrn.2008.08.005Get rights and content

Objective

We sought to determine analytically the potassium content of different varieties of raw potatoes, and to estimate the amount of potassium that can be extracted or leached from raw potatoes by cooking.

Design and Methods

Six different varieties of fresh potatoes were obtained from the Whole Foods Market in Manhasset, New York. Two different cooking methods (normal cooking [NC] and double cooking [DC]) were applied to each potato. Potassium was extracted from the ash of dried samples. The potassium content of aqueous extractions was ascertained by atomic absorption spectrophotometry.

Results

Mean potassium content was highest in the purple Viking potato (448.1 ± 60.5 mg [11.5 ± 1.6 mEq]/100 g [values are mean ± SD unless otherwise noted]), and lowest in the Idaho potato (295 ± 15.7 mg [7.6 ± 0.4 mEq]/100 g). All raw potatoes had a mean potassium content of about 300 mg (7.7 mEq)/100 g or greater. The DC method resulted in a greater reduction in potassium from raw potatoes than the NC method. All potatoes retained a mean potassium content greater than 200 mg (5.1 mEq)/100 g, using the NC versus the DC method.

Conclusion

The potassium content of the raw potatoes studied varied considerably, with most tubers retaining a moderate amount of potassium after leaching. This study showed that the DC method appears to be more effective than the NC method in leaching potassium from the potatoes studied. Our findings provide useful information for dietitians involved in menu planning for people on potassium-restricted diets.

Section snippets

Material Selection

Six different varieties of fresh potatoes (i.e., Idaho, also known as (AKA) russet, red bliss AKA red Dakota, Yukon gold, purple Viking, white rose, and Russian banana fingerling) for this study were obtained from the Whole Foods Market in Manhasset, New York. These potatoes are briefly described in Table 1.

Procedures for Preparing and Cooking the Potatoes

Raw potatoes were washed, peeled, washed again, surface-dried, and prepared for processing. Based on the results of Bower,4 and to maximize potassium leaching, sliced samples (≈3 mm) were

Results

The mean potassium content ± SD of the raw potatoes is shown in Table 2. The potassium content was highest in the purple Viking potato (448.1 ± 60.5 mg [11.5 ± 1.6 mEq]/100 g), and lowest in the Idaho potato (295 ± 15.7 mg [7.6 ± 0.4 mEq]/100 g). All raw potatoes had a mean potassium content of about 300 mg (7.7 mEq)/100 g or greater.

All cooked samples were lower in potassium content when compared with raw samples (Table 2). The DC method resulted in a greater reduction in potassium from raw

Discussion

The potassium content of 6 different varieties of potatoes commonly consumed in the United States was determined in this study. The published values of the potassium content of the russet and red potato varieties, as based on data from the United States Department of Agriculture (USDA), are presented in Table 2. It is difficult to determine whether the red potato variety analyzed by the USDA is similar to the one analyzed here. One known difference between the USDA results and our results is

Conclusions

The potassium content of the raw potatoes studied varied considerably, with most tubers retaining a moderate amount of potassium after leaching. This study showed that the DC method is effective in leaching potassium from the potatoes studied. People on potassium-restricted diets may be consuming these potatoes in their daily diets. The findings of this study provide useful information for dietitians involved in menu-planning for people on potassium-restricted diets.

Acknowledgments

The authors thank Rebecca Cendan and Theresa Marrone for their assistance in performing the experiments described here.

References (7)

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This study was supported by a research grant from the National Kidney Foundation Council on Renal Nutrition.

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