When cutting fruits and vegetables What does cut effect?

If you’re trying to eat healthily, vegetables are a no brainer. But did you know that how you prepare your veg could affect the nutrients you get from them?

Cook First, Then Cut

Most of us peel, chop, slice, dice, and even julienne our vegetables without a second thought about to how it affects them beyond how they look and taste. But vegetables are made up of cells just like any other plant, and cutting can open up those cells and disturb what lies inside.

Carrots, for example, contain a group of chemicals known as polyacetylenes .One of those chemicals is called falcarinol, and, in a study on rats, has been linked with a reduction in cancer risk. It’s too early to say whether falcarinol has any benefit to humans.1

To see how polyacetylenes like falcarinol were affected by different preparation methods, researchers cut carrots into disks, batons, or left them whole during cooking. They found that carrots left whole, retained the most polyacetylenes.2 This is likely because the surface area of the chopped veg is larger, allowing more nutrients to leach out during the cooking process.

So, if falcarinol and related chemicals do have an anti-cancer effect in humans, cooking your carrots before cutting them would be the way to make the most of that.

Cutting vs Shredding: Boosting Antioxidant Properties

Cutting some vegetables can increase their levels of a group of potentially beneficial chemicals known as polyphenol. Polyphenols aren’t nutrients in the same way that vitamins are, but they are abundant in most plant-based foods, including things like coffee, red wine, and tea.3

Polyphenols may have beneficial health effects through their antioxidant properties, meaning they can protect your cells from damage by stopping reactions with oxygen— although the science on that is not yet settled.4

To investigate how cutting food affects polyphenols, researchers looked at what happens to different vegetables – courgettes, white and red cabbage, iceberg lettuce, celery, carrot, parsnips, radish, sweet potatoes and potatoes – when they were “wounded” by cutting them with a knife, then shredding them in a food processor. Parsnips, lettuce, and celery all saw boosted polyphenol levels when they were shredded.5

So maybe next time you’re thinking about a nice recipe, think of how to include these shredded veggies to get the most polyphenol out of them!

Chopping & Why Your Food Goes Brown

Another thing to bear in mind is that cutting fruit and veg open exposes the insides to oxygen. Have you ever noticed that cut apples go brown quickly? That’s because of a process called enzymatic browning.6

Enzymes in the apples react with oxygen and compounds known as tannins, a type of polyphenol. This chain of events leads to the production of melanin – the same pigment that colours our skin and hair – making the exposed inside of the apple brown. At the same time, oxidisation causes the loss of some Vitamin C from the apples, too.6

It’s not just apples that suffer this fate. Other fruits like pears, grapes, and avocados, and vegetables like potatoes and lettuce, undergo enzymatic browning.7

Chop Then Refrigerate

Polyphenols from all kinds of fruit and veg are lost through oxidisation after they’re chopped. Storing your vegetables in the fridge will slow down the process (though not stop it entirely).

On the other hand, you might not want those polyphenols in the first place. Polyphenols actually have a slight bitter taste, which can be detected by some people even in small quantities.8

In that case, tearing rather than chopping might be a good tactic. Recipes will often call for you to tear herbs like basil, for example. Why? Because it’s been widely considered by chefs that tearing the leaves damages the cells less than cutting through them with a knife does. This might seem counterintuitive but tearing causes less damage because it runs down the edges of the plant’s cells rather than across or through them.

Use a Ceramic Knife Instead

Speaking of knives, there is one-way food tech that might be able to help in the fight against browning fruits and vegetables: the ceramic knife.

Lots of metal knives contain iron or copper, which can speed up the enzymatic browning reaction. So, if you switch to a chemically unreactive ceramic or plastic knife you can actually slow down the process of browning slightly. Having a sharp knife also helps reduce the damage to the vegetable’s tissues by cutting through fewer cells.9

The Take-away

The main thing, though, is to make sure you eat enough vegetables in the first place. If that means dicing and slicing them, even with a metal knife, to make them palatable, go for it.

All of the changes that come about from different preparation methods pale in comparison to the extra vitamins, minerals, and other nutrients you get when you add an extra vegetable or two to your dinner.

How do you prefer to prep your vegetables? Let us know in the comments!

Flavor really does depend on how you slice it, experts tell us — though the reasons why are complicated.

Paul Williams

The food processor is, for me, hugely disappointing. Before owning one, I used to see them looking all shiny and powerful in the department store, and I'd fantasize about never chopping a vegetable by hand again. I failed to consider that cookbook authors have particular ideas about how each ingredient should be prepped. The food processor, no matter how many blades it may come with, often doesn't cut it.

Take this recipe for lettuce wraps with hoisin-peanut sauce. It's one of my go-to meals. To pull it off correctly, I'm instructed to mince the shallot, thinly slice the green onions, chop the cilantro, grate the ginger, and cut the cucumbers and carrots into matchsticks. Sheesh. I'd really rather just throw the ingredients in the food processor and move on. I've often wondered whether all this attention to the size and geometry of my produce cuts really matters.

To find out, I spoke with food experts about whether slicing, dicing, julienning, or any of the myriad cutting techniques affect flavor. The general consensus: Yes!

"We actually teach that right from the beginning — that cuts add different palatability," says Brendan Walsh, dean of culinary arts at the Culinary Institute of America.

But the reasons that a particular cut affects flavor are complicated, and sometimes mysterious even to restaurant critics, chefs and food scientists.

According to Leslie Brenner, restaurant critic for The Dallas Morning News and a cook and blogger for her own site, Cooks Without Borders, cutting is important because surface area can affect the flavor of vegetables.

"The cooking method is going to penetrate more finely cut vegetables more. You're going to get more of a reaction," she explains. She offers up okra as an example. "I cut them in half vertically and grill both sides, which gives them this wonderful charry flavor." She says the charred taste is enhanced by the increase in surface area created by the lengthwise cut. More finely cut vegetables will react more with other ingredients in a dish, like butter, salt or a marinade, she says.

But Pete Snaith, cooking and knife skills instructor and co-founder of Culinaria Cooking School in Vienna, Va., believes that the cut doesn't affect flavor so much as cooking time. "If you are going to add carrots to a dish, if you cut them smaller like a brunoise, which is 1/8 by 1/8 by 1/8 of an inch, and put them in at the end of the cooking process, they'll cook very quickly," he explains. Snaith also says that the cut affects texture, which some food experts believe affects flavor — or at least our perception of flavor.

"If you put a vegetable that is more rounded in your mouth, your mind is generally going to be thinking about something that has more of a succulence to it," says Walsh. "Something cut in squares is going to be a little bit more toothsome, with a jagged edge, and will give the impression of something rugged or tough. Your mind will think something is flavorful if it is smoother."

Bill Fuller, corporate chef for the Pittsburgh-based big Burrito Restaurant Group (bBRG), agrees. "Flavor is the taste of what is in your mouth, but it is also partly textural," he says. "If you slice a radish really thin, you just get the flavor without the snap pop crunch, which is really an important part of the radish."

Aroma also contributes to flavor, and Fuller believes different cuts can make certain fruits and vegetables smell differently. "With a tomato, if you slice it and spread the slices out on a plate, you're going to get a lot more of the tomato smell than if it's quartered and piled up," he says. "So you're getting a lot of tomato aroma when you eat. I think a wedge of tomato doesn't taste nearly as good as a slice of tomato."

Food scientists study exactly that phenomenon. "Every different type of produce is different in terms of the chemistry and how it responds to cutting or crushing," explains Charles Forney, a physiologist for Agriculture and Agri-Food Canada who studies how produce changes after it's harvested.

Forney says that as you cut a tomato, you break open cells that release an enzyme. This enzyme triggers a chemical reaction that produces much of the aroma we associate with freshly cut tomatoes. Forney refers to this aroma as the tomato's "green notes" and says that a similar reaction occurs in freshly cut grass. The more thinly you slice a tomato, the more enzymes you release, and the more of these green notes you get.

We also kick-start chemical processes when we cut broccoli, cauliflower and cabbage. The enzymes released when we slice these veggies start a reaction that produces compounds that contain sulfur. These sulfur compounds create the pungent, burning sensation you get when you eat some cabbages. The more you cut the veggie, the more compounds are produced.

Without enzymes, onions and garlic also wouldn't be nearly as flavorful. "If you cut an onion or garlic, you release an enzyme called alliinase that produces the typical pungency or onion or garlic aroma, which really isn't there when it's intact," explains Forney. "The enzymatic reaction forms the flavor — so the more finely it's cut, the more flavor that will be released."

So it seems that I really do need to follow each recipe's detailed demands for precisely cut produce. For many vegetables and fruits, the cut does make the flavor. Cuts affect cooking process, texture and aroma — and perhaps something even less tangible.

"We've gone beyond the point of where we think about food as just something that your taste buds pick up," explains Walsh. "When we talk about cuts, we think about how that ultimately is going to make dishes that are going to have appeal. Inside a kitchen, chefs will talk about a sexy quality to flavor or texture. That is something that cuts can do. They add that sexy quality." Copyright 2019 NPR. To see more, visit https://www.npr.org.