Editor’s Note: This article has been reprinted. It was originally published on June 5, 2017.
Knives have many uses in the kitchen. If you want a really elegant look, the right knife, combined with the right technique, can produce perfect julienne or chiffonade slices. But there are other things the right knife can do that you may not be aware of yet. One of the most important is increasing the nutrients that foods provide to your body.
It wasn’t long before aspiring chefs were chopping leafy greens so as not to damage them. Chopping lettuce and spinach for salad was considered impolite. An article in The Conversation summed up the dilemma facing chefs very well:1
“We have long believed that shredding vegetables, especially lettuce leaves, is the best way to preserve nutrients. The idea here is that shredding leaves disrupts the plant cells less than chopping. Directly shredding leaves allows their contents to leak out. This means that nutrients, especially minerals like potassium, can leak out.”
Chopping vegetables releases more polyphenols.
However, there is a school of thought that says that chopping vegetables—at least some—increases the amount of polyphenols they provide. These are only found in plants, Polyphenols They perform many different functions, such as providing color to the plant and protecting it from UV damage.
If some vegetables are scratched or cut, such as: celery, white carrot and lettuceEating vegetables can increase the production of polyphenols to defend against further harm. If an animal tries to eat them, for example, the bitterness of the polyphenols may prevent it from taking a second bite. In humans, chopping vegetables may increase the availability of their bioactive compounds, and health benefits may be derived from the “synergistic” combinations of phytochemicals.2
Antioxidants are important compounds that help protect you from damage. free radicals Plus, polyphenols are awesome. They’re the most abundant antioxidants in the American diet, according to the American Journal of Clinical Nutrition, providing intake levels 10 times higher than vitamin C, and 100 times higher than vitamin E or carotenoids.3
Nutrition Today4 He pointed to a wide range of health benefits attributed to polyphenols in foods, particularly in “reducing the risk of three common health conditions – Urinary tract infections“Among these benefits are cardiovascular disease and type 2 diabetes,” although the report itself cautioned that such benefits are not yet “settled science.”
One study showed that depending on the type of tissue of the fruit or vegetable, “cutting” or cutting the vegetable may also increase its antioxidant capacity. zucchiniWhite and red cabbage, iceberg lettucecelery, carrotwhite carrots, red radish, Sweet Potato White potatoes and potatoes have been evaluated for several nutritional properties:5
“Phenolic changes ranged from a 26% decrease to an increase of up to 191%, while changes in antioxidant capacity ranged from a 51% decrease to an increase of up to 442%. Ascorbic acid decreased by up to 82%, while changes in anthocyanins and carotenoids were less pronounced.”
Cutting vegetables affects their nutritional value and color.
Sometimes cutting vegetables can lead to a problem that even seasoned chefs are keen to address: enzyme browning. You’ve probably seen this phenomenon where peeled potatoes turn an ugly brown color before they reach the second cut. It’s caused by the enzyme polyphenol oxidase, which breaks down polyphenols. Sometimes it’s just oxygen reaching the freshly cut vegetables, causing polyphenol oxidase and polyphenols, which are plant chemicals, to mix.
Phenolic compounds turn brown, which is why some cut foods turn brown. Believe it or not, the knife you use can make a big difference. It’s all about how quickly the browning happens, and that depends on the knife you use.
Iron and copper increase the rate of browning, and this is the component that most stainless steel knives are made of, along with other metals. When cutting, vegetables get a triple dose of oxygen and the mixture created by mixing the above metals.
But there are alternatives. Ceramic and plastic knives are “chemically inert,” which is said to slow down the browning process. In testing, Cook’s Illustrated magazine showed6 Researchers found that using a plastic knife delayed the tanning process by a full day longer than using a metal knife or tearing by hand. Ceramic and stainless steel knives were also tested, and while neither completely prevented rust, the results were significantly better with the ceramic knife.
Instead of replacing all of your other knives, you can use ceramic blades to complement your other cutlery.7 It is best for chopping fruits, vegetables and boneless meats, but not for chopping meat. Frozen foodsmeat with bones or cheese (due to their tendency to stick) or use the blade to crush foods such as garlic.
Taste, texture and cooling
Cutting can also change the texture, making some foods soft and mushy, as well as the flavor. Refrigeration can slow down both of these processes. The conversation notes:8
“Refrigeration may help slow the rate of this browning reaction and thus help preserve the potentially beneficial polyphenol content. This works because the cold temperatures in the refrigerator slow down the chemical reactions, which would normally lead to the degradation of polyphenols…
But the process of producing polyphenols from vegetables (e.g. after cutting) often involves consuming vitamin C. So, nutritionally, it may be like robbing Peter to pay Paul, and there may be no overall benefits.”
Chopping vegetables can change their taste, making them a little bitter. But chopping leafy greens and herbs before adding them to a recipe can bring out the flavor that removing them from the stem won’t, and your teeth won’t do the job well enough to extract the nutritional benefits. According to The Kitchn:9
“When you’re twisting and chopping herbs into small, delicious pieces to flavor your dishes, only the cells that the knife hits release their herbal oils into your food. If you’re tossing them into something like a sauce that’s going to cook for a long time, don’t worry, the oils mixed with the heat from the stove will eventually leak out.”
Five Hardest Vegetables to Cut and How to Cut Them
Every now and then it’s nice to broaden your horizons and have something a little different for dinner. If you’re hesitant about eating a certain vegetable because you’re not sure how to use it, the following simple steps will help. You’ll notice that using certain knives makes the task easier, as does using a cutting board.
artichoke
They look like big, rubbery flowers, but often you want to get to the tender core, and that takes a little know-how.10
directions
- Pull back the outer green leaves to reveal the lighter yellow leaves.
- Use a serrated knife to cut off the top third of the artichoke (which will reveal the top of the tightly folded purple artichoke “petals”) and the bottom of the stem.
- Use a paring knife to peel off the yellow top and sides to get to the core, then cut off the outside of the stalk, similar to peeling a broccoli stalk. Cut carefully so you don’t start peeling off the core.
- Now that you have a pale onion with the purple feathery “choke” intact, use a paring knife and spoon to carefully remove it, and you’re done.
Beetroot
Sometimes known as beets, these versatile vegetables are delicious and hearty in cold salads or hot soups. But there’s a trick to keeping them looking their best.11
directions
- Use a sharp knife to cut off the green parts, but be sure to leave about a half inch of leafy stems at the top.
- Scrub the beets with a brush and cook in enough boiling water to cover them, inserting a fork to check for doneness, then stop the cooking process by immersing them in cold water.
- Once cool, use a paring knife to cut off the stem, then rub the skin with kitchen paper; it should peel off easily. Cut into slices or cubes.
Spaghetti squash
These vegetables require a sturdy knife, fork and spoon.12
directions
- Use your knife to pierce the skin all the way through to allow steam to escape while cooking.
- Bake whole in a preheated 400°F oven for 10 minutes or until tender enough to cut in half.
- Place the squash on a cutting board and cut it lengthwise.
- Use a spoon to remove the seeds, then use a fork to scrape the squash, which falls in strands like spaghetti, onto a serving plate.
Swedish cabbage
It tastes a lot like the heart of cabbage or broccoli, and a sharp, sturdy knife, plus a vegetable peeler, will get to the white goodness inside.13
directions
- Cut off the stem and leaves, then cut the white cabbage into quarters.
- Cut the core (about an inch square) in half and discard. Remove the skin with a peeler.
- Cut the slices into matchsticks, julienne, or cubes.
Celery
Also known as “knob celery,” celeriac looks like a tough, fibrous bulb of compressed roots, but if you dig deep, it tastes like a sturdy celery, and is great in soups, stews, or raw in salads. All you need is a sharp knife.14
directions
- Cut off the top, which includes the leaves as well as the base, allowing the “handle” to sit flat on your cutting board.
- Use your sharp knife to peel the sides into wide strips, keeping as much of the white vegetable inside as possible.
- Cut into slices, julienne or wedges as desired, and place the pieces in cold water with a little lemon juice to prevent them from turning brown.
Note about vegetables
Unfortunately, only 27% of Americans eat what they should for optimal health.15 The bottom line is that cutting, slicing or otherwise “cutting” vegetables helps release more polyphenols than you would get if you simply bit into them, but the bottom line is that you need to eat adequate amounts of well-cooked vegetables to ensure you get the health benefits, including polyphenols, they provide.
