Kale, or “borecole” (Brassica oleracea), is a cruciferous vegetable in the Acephala Cultivar group with green or purple leaves and extremely high nutrient density. Kale is descendent from the wild cabbage, a plant thought to have originated in Asia Minor brought to Europe in approximately 600 B.C. by groups of Celtic wanderers. Curly kale played an important role in early Europe as a significant crop during Roman times and a popular vegetable eaten by peasants in the Middle Ages until English settlers brought kale to the United States in the 17th century.
But enough of the boring stuff (no offense if you like history, I am just really bad at it = no fun)...
The leaves of the kale plant provide an earthy flavor and more nutritional value in relation to caloric content than almost any other food around. It is in season from the middle of winter through the beginning of spring when it has a sweeter taste and is more widely available. It is easy to grow and can grow in colder temperatures where a light frost will produce especially sweet kale leaves. However, kale can be found at most markets year round.
Kinds of kale
The dark leafy greens from the Brassica family have gained recent widespread attention due to their health-promoting, sulfur-containing phytonutrients. There are several varieties of kale, including curly kale, ornamental kale, and dinosaur (or Lacinato or Tuscan) kale, all of which differ in taste, texture, and appearance.
When choosing kale at the market, produce should be chosen with firm, deeply colored leaves and moist hardy stems. Kale should be kept in a cool environment since warm temperatures will cause it to wilt and will negatively affect its flavor. The leaves should be free from signs of browning, yellowing, and small holes. Choose kale with smaller-sized leaves for a more tender, milder flavor than those with larger leaves. To store, place kale in a plastic storage bag removing as much of the air from the bag as possible. Store in the refrigerator where it will keep for 5 days. The longer it is stored, the more bitter the taste becomes. Do not wash kale before storing because exposure to water encourages spoilage.
Kale has high antioxidant and anti-inflammatory nutrients, much-needed micronutrients that are deficient in those with Celiac (as discussed in the previous section), and cancer-preventive nutrients called "glucosinolates". Kale is an excellent source of vitamin A (in the form of carotenoids), vitamin C, vitamin K, copper, and manganese. It is a very good source of vitamin B6, dietary fiber, calcium, potassium, vitamin E, vitamin B2, iron, magnesium, vitamin B1, omega-3 fatty acids phosphorus, protein, folate, and niacin. Also, kale's vitamin K content is nearly twice that of vitamin K as most of its fellow cruciferous vegetables.
In addition to conventional antioxidants like vitamin C, beta-carotene, and manganese, kale also provides us with at least 45 different recently discovered flavonoids, including kaempferol and quercetin. Many of the flavonoids in kale are also now known to function not only as antioxidants, but also as anti-inflammatory compounds.
Furthermore, kale houses a unique blend of cancer-preventing glucosinolates, making this vegetable a prime directive of current nutritional research. It is an especially rich source of glucosinolates, and once kale is eaten and digested, these glucosinolates are converted by the body into the cancer preventive compounds. Amazingly, some of this conversion process has already taken place inside the kale, prior to consumption.
When we eat kale, whether raw or cooked, fiber-related nutrients bind together with some of the bile acids in the intestine in such a way that they simply stay inside the intestine and pass out of our body in a bowel movement, rather than getting absorbed along with the fat they have emulsified. Therefore, our liver triggers the replacement of the lost bile acids by drawing upon the body’s existing supply of cholesterol, consequently lowering cholesterol levels.
Kale also plays a key role in the support of the body's detoxification processes. The isothiocyanates (ITCs) dervided from kale's glucosinolates have demonstrated abilities to help regulate detoxification activities in our cells. The ITCs made from kale's glucosinolates have been shown to favorably modify both detox steps (Phase I and Phase II), allowing the body to better cope with toxic exposure, whether from our environment or from our food.
Storage and prep
As previously discussed, in order to properly store kale, place it in a plastic storage bag removing as much of the air from the bag as possible in the refrigerator where it will keep for up to 5 days. The longer it is stored, the more bitter the taste becomes. Do not wash kale before storing because exposure to water encourages spoilage from bacterial growth.
Since the kale is not washed prior to storage, the kale should be washed under cold water prior to preparation in order to reduce the number of microorganisms on the produce. Wash water should be no more than 10 degrees colder than produce to prevent the entrance of microorganisms into the stem or blossom end of the produce. The FDA advises against using commercial produce washes because the safety of their residues has not been evaluated and their effectiveness has not been tested or standardized. Separate and individually rinse the leaves of the kale. If there is still excess dirt, immersing the leaves in a bowl of cold water for a few minutes helps loosen it before rinsing again. After washing, blot dry with paper towels or use a salad spinner to remove excess moisture.
(Drum roll, please....) Why you should eat kale with lemon!
Kale has many health benefits, but the way the kale is prepared can change its nutrition. The best way to prepare it is to steam kale for 5 minutes to maximize the nutritional value when consumed. To ensure quick and even cooking cut the leaves into 1/2" slices and the stems into 1/4" lengths. Let them sit for at least 5 minutes to enhance their health-promoting qualities before steaming. Sprinkling with lemon juice before letting them sit can further enhance its beneficial phytonutrient concentration. Vitamin C from the lemons helps make plant-based iron, which carries oxygen to red blood cells and hinders muscle fatigue, more absorbable. In fact, it actually converts much of the plant-based iron into a form that's similar to what's found in fish and red meats. Once the kale is cooked, lightly spraying the oil can increase vitamin A absorption, since this vitamin is oil-soluble.
So, there you have it... Now go buy some kale (and lemons)!
Check out our recipe for sesame kale chips!