Soaking to Reduce Potassium and Phosphorus Content of Foods.

Objectives: To achieve and maintain normal serum potassium and phosphorus levels reducing potassium and phosphorus intake is frequently recommended for adults living with chronic kidney disease. Exploring food preparation methods to reduce potassium and phosphorus content appears warranted. The study aim is to determine the impact of soaking foods in hot water on potassium and phosphorus content in a variety of plant- and animal-based foods.

Methods: Twenty foods were selected that are common staples in Brazilian diet patterns. Food was soaked for 5-10 minutes in deionized water that had been brought to a boil and then removed from heat using a 5-part water to 1-part sample ratio. The potassium content was determined by flame photometry. The phosphorus content was determined by visible ultraviolet spectrophotometry.

Results: Soaking foods resulted in a reduction in potassium and phosphorus. Potassium reduction in beef, green leafy vegetables, and grains was 40-49%; in chicken, fish, and nonleafy vegetables 30-39%; and tubers 10-20%. Phosphorus reduction in grains and beans was 30-39%; in nonleafy vegetables 20-29%; and beef, chicken, and fish 10-20%.

Conclusions: Soaking foods in hot water for 5-10 minutes reduces potassium and phosphorus content. Using this technique to prepare foods may be a more acceptable alternative to longer demineralization periods making it easier for adults living with chronic kidney disease to follow diet recommendations.