Frozen Bananas and Potassium

Bananas are famous for their high potassium content. According to the USDA National Nutrient Database, a large banana has 487 mg of potassium. This contributes 10 percent of your adequate intake level of the essential mineral and electrolyte. For convenience or taste, you may choose to freeze ripe bananas or purchase bananas already frozen. If you are a fan of frozen bananas, you may be wondering whether freezing compromises the nutritional integrity of this fruit.

The Process of Freezing Bananas

Raw foodies advocate the health benefits of consuming produce in its most natural form. While frozen fruit is minimally tampered with, manufacturers usually blanch fruit before freezing it, as an antibacterial precaution. Fruit is sometimes then treated with an acid, such as ascorbic acid, to prevent oxidation and browning. Frozen fruit must be stored with an airtight seal and should be used within a year of freezing. While potassium is not affected by freezing temperatures, it is the blanching process that may cause some potassium to be lost from frozen bananas.

Effects of Blanching on Potassium Content

Blanching means submerging banana slices in boiling water for 30 to 45 seconds, then cooling them immediately in ice water. Blanching may reduce potassium content, according to a 2006 study in the “International Journal of Food Sciences and Nutrition.” In this study, potassium levels of grass pea seeds were reduced after blanching. Minute amounts of potassium may leach out into boiling water during this process. If you choose to freeze your own bananas without blanching them first, you may preserve more of the potassium but increase your chances of foodborne illness.

Effects of Freezing on Potassium Content

Frozen fruit is chilled, then stored at -10 degrees Fahrenheit. It is important to bring fruit to freezing temperatures quickly so small ice crystals form inside the cells. When fruit is not frozen quickly enough, large ice crystals form, breaking cell walls and resulting in a product that is mushy when thawed. Because it is the water of the banana cells that is freezing, the potassium content is not significantly affected. Potassium is a mineral that is not susceptible to degradation by freezing.

Should You Eat Frozen Bananas?

Ultimately, you cannot underestimate the importance of fruits and vegetables in your diet. While frozen bananas may have a slightly lower potassium content, they are still a great addition to a healthy diet. If you freeze your own bananas, peel them and blanch them whole. Cutting bananas into slices before blanching increases the surface area and the potential for potassium to be lost. Add frozen bananas to smoothies or banana bread, or dip them in chocolate for a summer treat.

References

• USDA: Chapter 5 Potassium
• USDA National Nutrient Database: Search (bananas, raw, large)
• New Mexico State University; Cooperative Extension: Freezing Fruit Basics
• "International Journal of Food Sciences and Nutrition"; Effect of Maturity Stage on the Content of Ash Components in Raw and Preserved Grass Pea (Lathyrus sativus L.) Seeds; Lisiewska Z., et. al., Feb 2006