Preserving fresh walnuts to maintain nutritional content

Learn how to properly store walnuts to prevent them from turning rancid.

The nutrient and phytochemical benefits contained in walnuts make them a terrific heart healthy food choice. With the high oil content of walnuts (18 grams per ounce) Michigan State University Extension encourages proper storage and temperature control to maintain freshness to keep this tree nut from turning rancid.

A one ounce serving of walnuts equals 1/4 cup or 12 to 14 walnut halves and provides important omega-3 fatty acids, two grams of fiber and four grams of protein. Walnuts are sodium free, cholesterol free and contain twice the antioxidants compared to other nuts.

It is the oil content of walnuts, though mostly healthier polyunsaturated fat, that makes proper storage important. Exposure to warm temperatures for long periods of time will cause the fat in walnuts to change and turn rancid. You can tell walnuts are turning old if they are rubbery or shriveled. They have turned rancid if they have a strange odor similar to paint thinner. Throw away rancid walnuts!

Store shelled or unshelled walnuts safely in an airtight container and store in a cool, dry place. The refrigerator is a great choice as walnuts will remain fresh for up to three months. You can also freeze walnuts for up to one year.

Walnuts will absorb odors so it is best to place them at distance from foods with strong odors, such as onions. Airtight containers provide the best protection to maintain freshness. When purchasing walnuts in bulk it is best to transfer the nuts into airtight containers when you get home.

Walnuts are available year-round in grocery stores, and readily seen during the harvest months of August through November. California boasts growing 99 percent of the walnuts used in the U.S., however in Michigan locally grown black walnuts can be found.

Proper storage is easy and helps to maintain the delicious, crunchy taste and health benefits of walnuts, making them a perfect choice for your family’s shopping list.

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