Real Food Right Now and How to Cook It: Walnuts

My husband has family in Modena, Italy. If you've never been, I can tell you that it is a culinary wonderland - the city and the surrounding Emilia Romagna region is the home of (real) balsamic vinegar, fried dough squares called gnocco fritto that I can never get enough of, prosciutto, Parmigiano-Reggiano, tortelloni, mortadella...the list goes on and on. It is hard to find a region that is more chock-a-block with good things to eat and drink than Modena and its neighbors. So it may be a little surprising, with all of this culinary bounty, that one of the first things my husband and I seek out when we visit is nocino de Modena, a thick, sweet liqueur made from unripe walnuts. It is difficult to find here in the US, and so we savor every walnut-y drop (and bring back as many bottles as we can). Some year, I'm going to make it myself from green walnuts grown on my grandma's farm.

A Brief History

According to Edible: An Illustrated Guide to the World's Food Plants, walnuts (of different species) are native to eastern Asia, southern Europe and North and South America. The nuts have been found in Iron Age archeological sites in Europe and were mentioned in the Bible (most notably in the Song of Solomon). The ancient Greeks, Romans and Persians cultivated walnuts; The Oxford Companion to Food notes that indigenous Greek walnuts were replaced by the Persian varietals, superior in taste, size and oil content. The Persian walnut made its way to China by 400 AD, and was introduced to England in the 15th century, although cultivation of the nut never really took off in England. English merchants helped spread the nut to much of the rest of the world, though, and the name "English" walnut stuck.

Many Native American tribes used the indigenous black walnut in their cuisines (the Apache were apparently especially fond of the nuts, mixing it into pemmican and eating the nuts fresh). Early New England settlers brought the Persian walnut to North America, where it quickly dominated the harder-to-hull black walnut. According to the California Walnut Board, Franciscan monks were the first to cultivate the nuts in California in the 1700s. The first commercial plantings of the nut in California weren't until 1867.

Factual Nibbles 

  • Apparently, cracking walnuts with one's head is a thing
  • The green walnuts used to make nocino walnut liqueur are traditionally harvested on St. John's eve, June 23rd.
  • Walnuts' genus name, Juglans, is derived from the Latin iovis glans, or "Jupiter's nut." (Jupiter, if you may recall, is the Roman equivalent of the Greek god Zeus.)
  • Walnuts were thrown at Roman weddings as a symbol of fertility.
  • Luther Burbank, he of the famous Russet-Burbank (aka "Idaho") potato, is credited with developing improved California walnut cultivars. 
  • Most walnuts sold in their shells in the US are bleached to "improve" their appearance. (Organic nuts are the exception.)
  • Black walnut trees produce a substance that is toxic to other plants; the tree is also toxic to horses.

Cultivation

By far the most common type of walnut used in the kitchen is the English (or Persian) walnut (Juglans regia). Other types of walnuts include the North American black walnut and the North American butternut (also known as the white walnut). In temperate North America, walnuts are important components of a healthy deciduous forest. Walnut fruit is green and fleshy and surrounds the walnut seed. English walnut trees take up to seven years before they bear fruit ready for harvesting. Black walnuts are primarily foraged; there are only a few commercial black walnut farms in the US. Black walnut foraging is a common fall pastime (and money maker) in parts of the United States. Here's a video of Ozark Mountain people foraging for the nut. California grows the vast majority of English walnuts in the US. China, Iran, the US and Turkey are the top global producers.

Seasonality

Walnuts are generally harvested from August through November. Here is a great photo essay of a walnut harvest in California.

Environmental Impact

In general, even conventionally grown walnuts show little pesticide residue on the shelled nut. However, pesticides used in non-organic walnut production are hazardous to farmworkers and to local ecology, so choose organic walnuts whenever possible or talk to your local walnut farmer about his/her growing practices. (*And check out our Real Food Rule of Thumb for more information.)

The real concern with walnuts has to do with the trees' use of water. Tom Philpott, writing in Mother Jones, recently noted the heavy amount of water needed to keep California's almond industry afloat, so it should come as no surprise that California walnuts, which make up around 99 percent of all walnuts grown in the US, require a significant amount of water as well. What is really concerning is that, despite the drought, 2014 is expected to be a banner year for walnuts, with the state producing a record amount of the nuts. How is this possible, given that nut trees require substantial amounts of water? According to this article, it's because California walnut farmers, unable to rely on surface water (i.e., water from rivers and lakes) affected by the drought, have been pumping huge amounts of ground water, a practice that has only recently been regulated in the state (but, according to the recent law, local agencies have until 2040 to enforce them - so until then, regulations are toothless).

Unfortunately, it's also looking as though climate change will greatly affect walnut trees in particular. According to researchers at Perdue University, the trees are particularly sensitive to extreme cold and heat, both hallmarks of climate change-related weather events. The university has a breeding program in place to try to develop climate-change resistant varieties of the trees.

Characteristics

By far, you are most likely to come across English walnuts at the market. They are large, two-lobed and wrinkly like a brain, and vary in color from light beige to dark brown. English walnuts are mild in flavor with very little astringency. Black walnuts are far less common, but are said to be far superior in flavor than English, with more complex "walnut-y" flavor and more astringency. They are much harder to hull and extract from their shell - plus they stain something fierce. (Indeed, black walnuts have been used for centuries as a stain and a dye. You can make your own black walnut dye if you're the industrious type.) Hank Shaw over at Hunter, Angler, Gardener, Cook has a great post on foraging, hulling, shelling and extracting black walnuts - sounds positively exhausting, but worth it.

Nutrition and effects on the body

Walnuts are a wonder food. Like most nuts, they are high in protein and fiber. They're also loaded with nutrients, like Vitamin B6, folate, thiamin, iron, magnesium, copper and manganese. Walnuts are a great source of both omega-3 and -6 fatty acids, essential fats that the body needs to build brain and nerve cells. They also may lower the risk of heart disease. Black walnuts in particular have been used for centuries as a traditional medicine. Said to treat parasites and constipation, black walnut extract is also used to help with fungal infections. Black walnuts are also used as a natural hair dye - if you're a hardcore DIY type, you can make your own.

What to Do with It and Cooking

Walnuts are great additions to both savory and sweet dishes. In the US, the nuts are most commonly eaten out of hand or added to baked goods and other desserts. They have a natural affinity with chocolate, maple syrup, warming spices (think cinnamon and nutmeg), bananas, lemon and vanilla. Walnuts are best toasted - toasting any nut makes them nuttier and crisper, with a deeper, more complex flavor. Aside from their more familiar addition to sweets, walnuts are used extensively around the world in savory dishes. I love to chop toasted walnuts and add them to salads and as a topping for cooked vegetables like green beans. I also frequently substitute walnuts for pine nuts in traditional basil pesto and when I make kale pesto. In Persian cuisine, walnuts are used extensively in savory dishes, ground and used as a thickener in stews, like this pomegranate and duck khoresh. In Italy, walnuts are ground and used as a sauce for pasta. The nuts are also made into soup - the French make a cream of walnut soup, the Chinese a walnut soup with rice flour and the Turks and Balkans a walnut soup with yogurt.

Walnut oil is pressed from the seeds and makes a delicious salad oil (its smoke point is low, so it doesn't do well in high-heat applications) or for drizzling on vegetables.

Storage

Store walnuts in an airtight container (I like glass canning jars with tight fitting lids) in the refrigerator for up to a month, or in the freezer for longer-term storage. Walnuts are particularly susceptible to rancidity, but cold temperatures help keep all nuts from going rancid. If your walnuts smell vaguely like pain thinner, they have gone rancid and should be tossed.

Stretching your food dollars through preservation

In England, pickled walnuts are a traditional accompaniment to blue cheeses (like Stilton), made from unripe (green) walnuts. Here's a recipe if you want to try your hand at making them. You can also make your own nocino, if you have access to green walnuts.

Recipe

Spiced Candied Walnuts with Fennel and Szechuan Peppercorn

These are perfect for snacking and make great little holiday gift bags. Toss chopped candied walnuts in salads, eat them alongside cheese (cheddar and goat cheese are nice), or chop them up and put them in your next quickbread or atop vanilla ice cream for an unexpected treat. This recipe can be easily doubled.

Note:  Szechuan peppercorn produces a lovely numbing-hot sensation on the tongue - if you can't find it, substitute black pepper instead.

Ingredients:
14 cup sugar
12 teaspoon cinnamon
12 teaspoon freshly ground Szechuan peppercorns (see note, above)
2 teaspoons whole fennel seeds
1 teaspoon kosher salt
1 tablespoons water
1 cup large, shelled walnut halves

Method:

  1. Preheat oven to 350F. Line a small baking sheet with tinfoil and lightly oil, or spray with cooking spray. 
  2. In a small bowl, mix the sugar, cinnamon, ground Szechuan peppercorns, fennel seeds, salt and water. Toss in the walnuts and gently mix with your hands to coat. 
  3. Spread the nuts in an even layer on the prepared baking sheet. Bake for about 15 minutes, or until the nuts are fragrant, stirring frequently with a fork while baking. 
  4. Remove from oven. Gently stir mixture again to prevent sticking. Let cool. Store in an airtight container for up to a week.

 

(*Real Food rule of thumb: We think that first and foremost, in terms of nutrition, people should eat lots of fruits and vegetables whether they are organic or not. The EWG's guide is a handy list, but we will point out here that the impacts of pesticides are not limited to your ingestion of them - agricultural chemicals also affect farmworkers and local waterways, both good reasons to buy organic, even those vegetables that carry a light pesticide load. Also, it has been demonstrated that produce grown by small-scale farmers, even those who are not certified organic, tends to have a lighter pesticide load than its industrially-produced counterpart, owing to industry's tendency toward large monocrops.)

This post was originally published in October 2014.