Asparagus: The Royal Vegetable

Asparagus

Spring is asparagus season, most commonly starting in April and ending in June. While we may enjoy asparagus all year long, it is most delicious and nutritious when eaten in season. Americans may appreciate the vegetable, but the love for this vegetable shines in Europe, especially in Germany, where it is often referred to as the “royal vegetable” or “king of vegetables.”  Each year during asparagus season, or Spargelzeit, many Germans enjoy seasonal meals made with the vegetable such as asparagus soup or a simple meal of potatoes and asparagus served with melted butter or hollandaise sauce. People drive from miles around to buy freshly-harvested asparagus from local farms or celebrate at local asparagus festivals. 

Native to the Eastern Mediterranean region, asparagus has been cultivated for at least 2,000 years. It is one of the few vegetables that is a perennial, which means that it does not need to be planted each year—the plants live around 15 years or more. Unlike the green asparagus, with which we are most familiar, white spears are the most prized type in many countries, including Germany. They are white because they are kept buried under the soil, where the lack of sunlight prevents them from turning green. This makes them more tender and sweeter. There are also varieties with a purple tint, which fades to green when cooked.

Nutrition

Asparagus is not only delicious, but also very nutrient-dense. Nutrient density refers to the amount of vitamins, minerals, and fiber as compared to the amount of calories. A cup of asparagus is only about 40 calories, and is an excellent source many essential nutrients such as vitamin K, folate, vitamin A, vitamin C, and thiamin. It is also a good source of vitamin E, riboflavin, niacin, B6, iron, potassium, copper, manganese, selenium, and fiber. Additionally, asparagus contains a specific fiber called inulin, which has prebiotic properties helping to feed gut microbes, and has been studied for its beneficial impact on the gut microbiome.

Nutrients in 1 cup cooked asparagus

Like most vegetables, asparagus is also a great source of phytonutrients, which have a range of benefits. For example, asparagus contains quercetin, which is linked to reduced cardiovascular disease, and saponins, which may positively impact cardiovascular health, immune function, and cancer risk. Glutathione is another phytochemical present in asparagus which is known as the body’s “master antioxidant” and is vital for the immune system and protecting cells from oxidative damage.

Storage and Preparation

Asparagus spears grow fast—during peak growing season, they can grow to their full length in just 24 hours! Its fast metabolic rate is one reason why it cannot be stored as long as some vegetables; it is best to eat it as soon as possible after purchase, with 2-5 days. When shopping, look for firm, smooth, straight, and bright green plants (or white or purple if you can find them), with compact tips. Store wrapped in plastic in the fridge. For best results, you can also place them upright in a jar with a little water, or wrap the bottom ends in a damp paper towel.

Often, the very bottom of the spear is tough, so this can be cut or broken off. For thick stalks, you may want to cut off the bottom inch, and then use a peeler to peel the rest of the bottom half. This can lead to less waste than cutting or breaking off a large portion of the bottom. Asparagus can be roasted, grilled, boiled, steamed, microwaved, pickled, or even eaten raw. It is often served with ingredients such as lemon, olive oil, butter, egg, hollandaise sauce, and parmesan cheese.

Try out one of these ideas, or explore your own!

  • Toss asparagus in olive oil, lightly sprinkle with salt and pepper, roast in the oven, and top with finely shredded parmesan cheese
  • Chop tender spears of asparagus into small pieces and add to a salad with a vinaigrette dressing
  • Sauté with onion, simmer in broth, then puree for a simple creamy soup
  • Chop finely, sauté, and add to scrambled eggs or an omelet
  • Makes a great addition to a stir fry with a variety of spring veggies, soy sauce, and garlic
  •  Rinse and trim spears and place in a microwave-safe bowl with a lid; add ¼ cup water and cook on high for about 3-7 minutes; toss with butter and lemon juice
Ribboned Asparagus Salad with Lemon (Adapted from Smitten Kitchen)
Ingredients:
  • 1 pound of asparagus
  • cup pine nuts or sliced almonds, toasted
  • 1 lemon
  • 1 TBSP olive oil
  • Sprinkle of salt
  • Sprinkle of black pepper
  • 1-2 oz Parmesan cheese
Directions:
  1. Lay asparagus stalk flat on the cutting board, holding onto the tough end. Using a vegetable peeler, shave ribbons from the stalk, peeling from the tough end to the tip. Discard the tough end when done.
  2. Pile ribbons into serving platter and add lemon juice, olive oil, salt, and pepper to taste. Toss gently.
  3. Use the vegetable peeler to shave pieces of Parmesan off the block. Top the salad with the shaved Parmesan and the toasted nuts.

Note: To toast nuts, bake at 350 degrees F for 5-10 minutes, tossing frequently.

Preserving

Late spring, tender green spears poke skyward, ready for harvest as some of the first local food crops of the season. Asparagus grows well in a variety of well-drained soils, from intentional fertile garden beds to roadside ditches. It is so anticipated to seek out the fresh green vegetable, that our most common species even boasts the noble Latin name, Asparagus officinalis.

The season for the Colorado crop does not last long, generally 4-6 weeks, sparking interest in suitable preservation techniques. Once harvested, the fibrous vegetable is often heat-treated, or cooked by some means, before eating, reducing food safety risk. As a low acid food, it has greater potential for pathogenic bacterial growth when processed improperly. Vegetables, such as green beans, cucumbers, and asparagus, do not meet the acidic pH of 4.6 that is required to control growth of pathogenic bacteria including Clostridium botulinum through processing. Safe asparagus preservation methods include following USDA approved pressure-canning, freezing, drying, or pickling recipes. Food preservation recommendations for Colorado residents, who all live at or above 3000 feet in elevation, are available online through CSU Extension. For all preservers, but especially beginners, taking a class offered through CSU Extension or chatting with a volunteer Master Food Safety Advisor may help clarify recommendations, enhance skills, and boost confidence in prevention of foodborne illness.

Pickling

Preservation by pickling is one of the oldest techniques utilized to preserve fruits and vegetables. The word pickle, comes from the Dutch word for brine, and is used to describe a food that has been preserved in an acidic brine. Historically, the practice of increasing the acidity of the food has been used for taste quality as well as for safely extending the shelf life of perishable foods. This should be done using an approved recipe, with standard 5% acetic acid vinegar, to make a brine completely covering the asparagus. The National Center for Home Food Preservation, based out of Georgia, provides resources on How Do I Pickle with recipes for pickled asparagus under Other Vegetable Pickles. Make sure to adjust process times for the local elevation. Current, trusted recipes should always be followed to limit pathogenic and spoilage microorganism growth that could arise from following poor practices passed on through generations including those that adhere to improper use of equipment or unacceptable ingredients.

Pickles, or a food preserved by being submerged under an acidic brine, can also be made through fermentation, by utilizing microorganisms to produce the acid necessary for preservation. Fermented pickled vegetables do not call for adding acid in a recipe, but will require lengthier time to cultivate beneficial bacteria under suitable conditions for safe growth. Pickling through fermentation does not require heat-treating the final product, but should be kept cold, as a perishable product, once desirable taste and texture qualities are achieved. Consumers should be aware that currently, an Extension tested recipe for fermented pickled asparagus is not available.

Safe pickling of vegetables will preserve health benefits of the vegetable, as well as develop a unique flavor profile, that will be enjoyable to consume well after the season for local, fresh asparagus has passed. Seasonings added to the brine, will permeate the asparagus spears, adding desirable flavor to the soured vegetable. Pickled asparagus can be consumed just like a commercially made pickle. The tender spears will lend a different texture than the traditional cucumber, which may be desirable for an appetizer relish tray, condiment on a favorite sandwich, or just straight from the jar! 

Sources:

http://asparagus.on.ca/asparagus-basics/
https://www.atlasobscura.com/places/european-asparagus-museum
https://www.cooksillustrated.com/how_tos/9894-peeling-asparagus-is-it-worth-the-fuss
http://www.michiganasparagus.org/#our-team
https://modernfarmer.com/2014/07/white-asparagus/
https://ndb.nal.usda.gov/ndb/search/list
https://smittenkitchen.com/2011/05/ribboned-asparagus-salad-with-lemon/