What Is a Walnut?

Buying, Cooking, and Recipes

Walnuts in wooden bowl
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The walnut is a type of tree nut that has a hard, tough shell. The inner meat looks sort of like a tiny brain and has a rich, sweet taste. The walnut is the most widely-consumed nut in the world and has been enjoyed for well over 8,000 years. The majority of commercial walnuts come from California and China. English walnuts and black walnuts are the two most common varieties. They're eaten as is after shelling or incorporated into delicious foods like bread, cakes, and even sauces for savory dishes.

Fast Facts

  • Common Varieties: English walnut, California black walnut
  • Edible Parts: Inner meat, skin
  • Preparation: Shelled then eaten whole or chopped or ground
  • Storage: Refrigerator 3 to 6 months, freezer 1 year

Varieties

There are over 50 species of walnut trees, all part of the Juglandaceae (or walnut) family. The most common variety sold and eaten is the English walnut (Juglans regia). It was originally known as the Persian walnut and also goes by the name of California or Mission walnut. It is native to Asia and the Balkans but today is grown commercially in Asia, Europe, and the western U.S. It has a mild taste and a thin shell that is easy to crack. 

The other common variety is the California black walnut (Juglans nigra), which is also simply called a black walnut. It's native to America, often growing wild in central and eastern regions. It has a thicker shell that is more difficult to crack, making commercial production more of a challenge. This walnut has a bolder, more earthy flavor and it can stain hands and clothing.

Walnut Uses

The meat inside the walnut, as well as the paper-like skin that covers it, is edible. It's a popular nut for snacking on whole. The meat can also be cut up for use in recipes. Chopped nuts can top a salad, fruit bowls, oatmeal, or yogurt. Roasted walnuts make a good addition to granola, vegetable dishes, wraps, and pasta. Finely chopped or ground walnuts are often added to bread, scones, and desserts as well as sauces and dips.

Walnut oil is an excellent—albeit expensive—choice for salad dressings, but not for high heat uses.

How to Cook With Walnuts

If it hasn't been done already, you will need to shell the walnuts using a nutcracker. When cracking black walnuts, wearing gloves is recommended to avoid staining your hands. Inside, you'll find whole walnut meat—it's typically split into two halves when prepared commercially. One pound of walnuts will yield about 2 cups of nutmeat. 

Recipes may require chopped or sliced walnuts. You may also want or need to toast walnuts, which enhances their earthy flavor and reduces bitterness. Do this before cutting. Some recipes also call for ground walnuts, which can be done in a food processor. It works best if the nuts are at room temperature and the processor bowl and blades are cool and completely dry.

What Does It Taste Like?

Walnut meat is rich, sweet, and earthy. The papery skin adds a nice bitterness.

Walnut Substitute

Pecans are a favorite substitute for walnuts as they're very similar. Pine nuts and hazelnuts are good options, too. Use the same measurement and preparation in the recipe.

You can replace 1 cup of walnuts with 2 to 4 tablespoons of walnut oil. Only do this if your recipe can handle the extra moisture and it's either uncooked or cooked at a low temperature.

For people with tree nut allergies, peanuts are a possible substitute using the same amount as walnuts. Pumpkin seeds are the closest in texture and have a mild flavor, so they're the top seed choice to replace whole or chopped walnuts. Sunflower seeds are a similar option while sesame seeds can replace crushed walnuts in some baked goods.

Walnut Recipes

Walnuts find their way into a variety of recipes. From pasta sauce to spreads and ice cream to cookies, you'll have plenty of delicious ways to use these nuts.

Where to Buy Walnuts

Walnuts can be found in most supermarkets, grocery stores, and natural food stores. They're also available online. You can forage the nuts when they drop from walnut trees in the fall. You will have to remove the outer green husk before getting to the shell, then allow them to dry for two weeks. Those nuts which grow on the sunnier side of the tree will have darker skin and a richer flavor.

Walnuts are sold both in and out of their shells. Walnuts in the shell range in size from jumbo to baby. They're more prevalent in late fall and winter in the produce section and are sold by the pound. If buying shelled, prepare for a higher price tag—these nuts are hard to crack, and the percentage of whole nut pieces is low. Shelled walnuts are offered halved, chopped, diced, sliced, chips, and ground year-round in the baking aisle. They may be raw or roasted and/or salted. These walnuts are typically packaged in plastic bags or round canisters, ranging in size from 2 ounces to 1 pound or more.

Avoid rubbery or shriveled nuts as this is an indication of age. Reject any walnut pieces that are cracked, pierced, or stained as these are signs of mold and they're not safe to eat. Shelled nuts should be brittle and snap easily.

Storage

Due to their high oil content, walnuts can quickly turn rancid and taste very bitter if not stored properly. For long-term storage, it is best to buy unshelled nuts and place them in the refrigerator for two to three months or freeze them up to one year. If using in a short time period you can keep in the pantry. Shelled walnuts should be kept refrigerated in an airtight container, lasting up to six months, and may be frozen up to a year. 

Nutrition and Benefits

Walnuts are viewed as one of the healthiest nuts. One cup has 200 calories, 3.89 grams carbohydrate, and 20 milligrams calcium. Walnuts are high in heart-healthy fats. The 20 grams of fat in a cup includes both monosaturated and polyunsaturated fats as well as beneficial omega-3 fatty acids. That, along with 5 grams protein and 2 grams of fiber, make them a filling snack. They should be eaten in moderation to maintain a healthy weight.

Walnuts rank the highest among nuts in antioxidants and polyphenols as well. They are a good source of copper, manganese, and copper, all of which play a role in bone health. Walnuts also provide iron, magnesium, phosphorus, and vitamins B6 and E. Almost 90 percent of the polyphenols are in the nut's skin. Though some people do, don't remove it if you want to take advantage of the benefits, which can aid digestion, weight management, and more.