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I have read that cut lettuce is more likely to brown on the edges than torn lettuce. The stated reasoning is that the lettuce leaves will tear between cell boundaries whereas if they are cut the cells are ruptured.

When preparing a largish salad tearing the leaves can take a lot more time than slicing.

How much of a difference does tearing actually make? Is it worth taking the time?
Are there some types of salads or dressings that will exacerbate the browning of cut leaves and the leaves should be torn instead?

Mien
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Sobachatina
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    Another reason to tear is that the hard, thick grain/stalk part in the middle of each leaf is often bitter, so you tear around that and discard it. – Cerberus Jun 05 '12 at 20:00
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    I'm not sure I buy that cell-boundary thing. I would rather say that tearing only uses light force that is evenly spread out, and the leaf only pulls apart where it is weakest. By contrast, cutting involves more pressure on the leaf around the prospective cut, so that the area touching the cut gets damaged more (observe a cut). And at some point the blade moves through the leaf rapidly, causing more damage. Moreover, if you are cutting several leaves at once, the knife will crash with some speed upon the underlying leaves once it cuts through the upper leave, causing more damage on impact. – Cerberus Jun 05 '12 at 20:26
  • @cerberus the cell boundary thing is true (at least for other things, but I don't doubt that it works for lettuce too). Also, if your knife is sharp, the force you have to use for cutting is less than for tearing. – rumtscho Jun 05 '12 at 21:03
  • @rumtscho: All right, I haven't read anything definitive about the cell boundaries. As to the force applied, it is really the force per unit of distance/area that matters, and the force applied when tearing is spread out all over the leaf, so that it only breaks where the force per area is highest, at the beginning of the tear. And a tear is a unique physical process in itself, where first nothing happens, then the entire tear suddenly appears as the threshold is passed and the plastic change happens where the structure is weakest. Pulling is just very different from pressing or friction. – Cerberus Jun 05 '12 at 22:27
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    Sounds like it's time for a experiment and a SA blog post :-) – TFD Jun 05 '12 at 23:02
  • I like the idea of an experiment, and (depending on what all happens tomorrow) may perform one. – BobMcGee Jun 06 '12 at 04:14
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    @BobMcGee if you do, take pictures and write a bit about it - we can use more blog posts – rumtscho Jun 06 '12 at 09:32
  • I am not big on gimmiky kitchen gadgets, but my wife got a plastic lettuce knife (like this: http://www.amazon.com/Zyliss-Fresh-Salad-Knife-Green/dp/B0018RYBW2) and it is great. You can cut the lettuce as small as you like but without the browning. Like a more accurate way to tear it. – zk. Jun 06 '12 at 16:17
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    Well, I did the experiment... after 2 hours, there's no distinguishable difference between cut and torn lettuce. Posting pictures and more detail in the next day or two. – BobMcGee Jun 08 '12 at 13:20
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    I'm not going to accept McGee as authoritative. Generally he's pretty good, but food authors are notorious for following tradition and established practice. There's all sorts of errors in well respected texts. (i.e. Always rinse pasta in Joy of Cooking). I'm also not going to accept "Common sense". It tells us that a heavier object will fall faster than a lighter object. There is really only one way to solve this: by experiment. Buy two romaine lettuce. Rip one, cut one. Spread them out on a towel, and take photos every 15 minutes for the first hour, and then every half hour thereafter. – Chris Cudmore Jun 08 '12 at 14:54
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    Not user BobMcGee. I meant author McGee – Chris Cudmore Jun 08 '12 at 18:59
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    Because with almost 8k Rep, BobMcGee is authoritative. – Chris Cudmore Jun 08 '12 at 20:13
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    @Chris Cudmore: Thanks, I think? Can anyone contribute on if I need to run the experiment longer than 2 hours, or with different conditions? – BobMcGee Jun 08 '12 at 22:58
  • If you're going to eat your salad within an hour, chopping with a knife is okay - if you're going to eat it later than that, tear - nutrient loss with knife chopping is much greater, which doesn't seem to be anything anyone's mentioned. Knife chopped lettuce kept for some hours is about as nutritionally valuable as the bag it's kept in. – bamboo Sep 18 '14 at 12:26
  • @bamboo how do you figure? Are you saying cut lettuce will lose more liquid and that liquid will contain important nutrients? – Preston Sep 22 '14 at 04:08
  • @PrestonFitzgerald - in essence, yes. As soon as you pull or crop a vegetable from where its growing, it starts to lose nutrients, but slowly - if you cut that vegetable up, especially leafy greens, nutrient loss is extreme, but less if torn. Best to buy them as whole as possible in the first place. – bamboo Sep 22 '14 at 08:48

8 Answers8

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Tearing is NOT worth the extra effort, tested experimentally.

Others have explored the theoretical reasons behind this, so I decided to test it in real life. I did this like so:

  • Green leaf lettuce from the local CSA
  • Cut one leaf with a sharp knife (stainless), and tore the second leaf carefully by hand (fast, clean tears)
  • Pieces were both wrapped in moist paper towels and left out at room temperature
  • Photographs were taken at 30 minute intervals

After 2 hours, the 2 leaves still look identical (picture below).

Cut (on the left), Torn (on the right):

Comparison of cut and torn lettuce

Provisos: knife was sharp and leaves were fresh and kept moist. A dull knife or more abusive handling of the leaves may yield bruising and faster browning. I am currently repeating this on a longer time scale, and may attempt with a dressing.

Practical take-away from the experiment:

I have found that in real life, it doesn't matter how you divide your leaves, as long as you don't apply dressing before storing for a prolonged period. The acidic dressing will wilt leaves and cause discoloration, and leading to a limp, soggy salad. The experiment supports that neither method leads to unacceptable browning within a short timeframe. In practice, I've only seen browning when lettuce is left overnight or longer, or when it is stored with dressing.

Cook's Illustrated confirms this with their experiment to see if plastic lettuce knives are worth it. They found that:

Though all lettuce began showing some browning on the ribs after 10 days, none showed any signs of browning on the cut or torn surfaces. After 12 days, the heads cut with metal knives showed faint signs of browning on these surfaces, and the lettuce cut with the plastic knife followed a day later. The torn lettuce was last to brown on its ruptured edges, starting to turn at 2 weeks.

Given that lettuce is browning on the ribs before it does on cut edges, the difference between cut and torn is no longer important. You're only adding 20% to the time before browning appears on cut surfaces. Most people will agree that after 2 weeks lettuce no longer has its full flavor. I have found that to get the freshest, best taste it should be eaten no more than 4 days after harvest.

So, if there difference between cut and torn is insignificant, why cut rather than tear?
It's faster and more consistent, especially if you have good knife skills and a sharp knife. You can cut a head of romaine in under a minute by knife, versus several times this by hand. You also don't have to worry about bruising leaves or making irregularly shaped pieces by accident, and you can choose to do large pieces or fine, fluffy shredded mixture. In my time in professional kitchens, I came to rely on the knife as an extension of my body, and you should too.

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BobMcGee
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  • There is a fifth grade science experiment that you van find online, that references McGee, and allows for pics at 6, 12, 24, and 48 hours. I do not doubt that after hours of sitting out, bruised lettuce will brown, and as tearing may cause more of this, it seems a valid experiment to show knives cause less trauma to some quantifiable extent. However, when I make a salad, I don't let it sit out for hours on end to oxidize. I toss with dressing and plate. How is this a practical proof? – mfg Jun 08 '12 at 13:52
  • @mfg: I am unclear what you are saying needs to be done to add more rigor. Are you saying (a) I need to test for a longer interval (b)Need to test with dressing on -- which is unusual b/c I always store dressing separately to get better flavor/texture, or (c)That I should seal the lettuce in an airtight container? – BobMcGee Jun 08 '12 at 23:10
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    Not many people cut lettuce more than a few hours before requiring it, even in the busiest places – TFD Jun 08 '12 at 23:25
  • @TFD: Yeah, I've never seen a cook use cut greens for more than a shift or so, and they generally only prep a small batch at a time, so it'll be fresh. I also don't generally see green salads dressed more than 20 minutes before plating. – BobMcGee Jun 08 '12 at 23:31
  • @bob you're take away I think is spot on; though I am more concerned with texture than the control if the cut, that is totally a subjective concern. As for rigor, I was just hoping to hear in a practical environment how/if the McGee citation mattered. From what I saw ok browning in the Cook's Illustrated article, there's no practical implication and correspondingly the citation is based on preference. – mfg Jun 09 '12 at 04:15
  • @BobMcGee before I award a canonical bounty on this, could you clarify why it is specifically NOT worth the effort? Sorry to drag this out, but your claim indicates that the results are basically a wash, that it "doesn't matter how you divide"; but thats not how it reads. Could you tie the bow and add to the conclusion the factors (i.e. is there more effort in tearing than cutting, is there a mitigating factor in taste/texture, etc) that compel you to make a *negative claim* rather than an equivalence (you have proven experimentally that it doesn't matter, rather than that one shouldn't tear)? – mfg Jun 14 '12 at 13:49
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    @mfg: I have edited the post to make more explicit why I prefer knife to hand tearing. I think you'll be happier with the result now? – BobMcGee Jun 14 '12 at 17:22
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Harold McGee discusses this in On Food And Cooking.

From the Preparing Salads section on page 318:

If the leaves need to be be divided into smaller pieces, this should be done with the least possible physical pressure, which can crush cells and initiate the development of off-flavours and darkened patches. Cutting with a sharp knife is generally the most effective method; tearing by hand requires squeezing, which may damage tender leaves.

Stefano
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  • While I appreciate an appeal to authority, this doesn't answer the question. – mfg Jun 06 '12 at 18:17
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    @mfg: why do you think it does not? – nico Jun 06 '12 at 19:10
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    Soba is asking a comparative question. You cite an authoritative but non-quantified claim as if it is definitive. What your citation doesn't answer is whether the "off-flavors and dark patches" sufficiently problematic as to make textual and presentation issues secondary. Also, are the off-flavors so overwhelming that dressing and other flavors do not compensate? Is this answer for a salad large or small made at home, or a best practice for a commercial kitchen? – mfg Jun 07 '12 at 00:03
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    There are three questions from the OP: 1. 'How much of a difference does tearing actually make?' The answer from McGee to that is that it is deleterious. 2. 'Is it worth taking the time?' The answer to that question is that it follows if the practice is deleterious then it is not worth the effort. 3. 'Are there some types of salads or dressings that will exacerbate the browning of cut leaves and the leaves should be torn instead?' This one is not answered although I would say given the huge amount dressings you can put on a salad it would involve a lot of experimentation to get a good answer. – Stefano Jun 07 '12 at 08:24
  • It is not deleterious of tearing; (1) preference for the knife is only "generally the most effective method", (2) the extent to which tearing isn't the most effective method is mediated by the extent to which squeezing occurs, and even so McGee makes no counterclaim against it, just states a preference otherwise, (3) this does not address the vast majority of any given salad preparation which will involve either vinegar, lemon juice, or some other acidulated liquid that would stem browning (& off-flavors?). The citation is not quantified; as presented, it's a blanket statement of preference. – mfg Jun 08 '12 at 11:08
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The browning of Lettuce leaves are due to the reaction of polyphenol(a chemical in any fruit or vegetable) and enzymes. This is due to two main causes:

  1. Aging
  2. Cell damage (i.e. from cutting, tearing)

Every cell has separate chambers for these two, if they somehow leak, and get mixed up, this would cause browning. Cutting and tearing cause damage to the cells, as is the same with apples, potatoes etc.

In any case, if the lettuce is eaten soon after it is prepared, as far as potential browning goes, it doesn’t matter if it was cut or ripped. Another thing is the dressing should always go on at the last moment because oil soaks into the leaves readily and makes them soggy.

Using brisk cutting motions, cut lettuce only if you plan to use it right away; cutting tends to split lettuce in the middle of cell. Tear lettuce for meals that you want to keep for later; tearing lettuce tends to break it along the natural cell walls.

mfg
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RUPASHREE
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In my experience lettuce will brown faster if cut instead of torn. However as most people are consuming the lettuce within the day, cutting won't make much of a difference if you plan on serving within the hour. It will generally show up the next morning.

Iceberg and Romaine are the two lettuce types that come to mind as being nasty for browning.

Also it was a lot worse in the days of carbon steel knives. Stainless steel knives don't cause the same extreme browning as the old school knives did. As DHayes suggested, using a lettuce knife will help even more.

Chef Flambe
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Tearing lettuce is worth the effort

It takes a reasonably similar amount of time as cutting, and a different but comparable amount of work. If you are planning on eating the salad soon, all the above comments apply as to the browning effect. However, browning isn't the only consideration when deciding between cutting and tearing.

Texture is as essential to the quality of a salad as any flavor, and twice as important to presentation as the edges browning. Tearing the salad's greens results in a more diverse texture that, outside the aesthetic of a shredded iceberg lettuce salad, is preferable to a uniform cut salad that lays limp as shredded paper on your plate.

Use cases

As your use preferences may vary based on the situation (e.g. if you want the leaves to glop up as much ranch dressing and cheese as possible), here are the use cases;

  • If you wish for your salad to present like it came out of a factory that makes garden salads, cutting is desirable; each bite will be the same and the greens will fade into the background to showcase the dressing.
    • Uniform cuts will also ensure your leaves glop up all the dressing. and form nice wads of gloop.
    • Uniform cuts will make the leaves into shapes their cellular structure doesn't support; that is, they will uniformly divide along knife cuts irrespective of cellular boundaries
  • If you wish your salad to serve plated or from a bowl and look like it was prepared leaf by leaf, ingredient by ingredient, tearing is desirable; each bite will uniquely showcase your greens and everything they are carrying.
    • Diverse and unique tears will coat nicely with dressing but allow excess to escape.
    • Diverse tears will shape pieces along their cellular structure boundaries as tearing will follow interstitial space rather than through cell walls (which are stronger in vegetable tissues than animal)

Approaches to tearing:

  • If you wish to reduce over-manipulation of the greens because the "off-flavors" are so overwhelming, or you notice your salads turning so brown, gently hold part of them against a flat surface and tear with the grain. It should tear along stalks and fibrous columns.

  • In terms of time, once the lettuce or greens are all in a colander and rinsed out, don't be gentle with them; grab them like a fistful of dollars and rip into them, dropping the tear-away into a bowl. For small greens, I find it effective to wad them up and twist through them; with larger leaves of green pressing them together and working my way down the stalk a half-inch at a time gets the job done in maybe an extra five seconds per bunch.

Discussion of claims:

Both cutting and tearing will rupture cell walls. My experience is that both work and neither too offensively. While I make no counterclaim against McGee, I just submit that the, as referenced,the citation does not exposit more than the following; (1) McGee's preference for the knife is pursuant to it being "generally the most effective method", (2) the extent to which tearing isn't the most effective method is mediated by the extent to which squeezing occurs, and even so McGee makes no counterclaim against tearing, just states a preference otherwise, and (3) McGee does not address the situational nature of this any given salad preparation; which will involve either vinegar, lemon juice, or some other acidulated liquid that would stem browning (& possibly off-flavors?). The citation is not quantified; as presented, it's a blanket generalization by McGee being masqueraded as science to justify a cooking myth.

With respect to the degree of browning I offer no quantifiable, practical, empirical evidence to (a) support that tearing does less browning, or (b) creates less "off-flavors" (per the McGee citation), as these are a non-specified traits; nor (c) an effective, empirical comparison between the degree to which (1) "off-flavors" practically impact a salad once other ingredients and dressing are added versus (2) "off-flavors" significantly impact a salad's quality relative to textural concerns.

Practically speaking, when preparing a salad for consumption (as opposed to cutting lettuce to oxidize), it has been my direct experience at home and in the commercial kitchen that neither knives nor hands cause more discoloration of leaf or flavor.

Our verdict? The plastic lettuce knife might stave off browning slightly longer than metal knives, but it's not worth the money or the extra drawer space. To prolong the life of lettuce by a day or two, stick to tearing by hand. Tearing allows leaves to break along their natural fault lines, rupturing fewer cells and reducing premature browning.

Injuries cutting through or scraping away the outer skin of produce will:

  • provide entry points for moulds and bacteria causing decay
  • increase water loss from the damaged area
  • cause an increase in respiration rate and thus heat production.

Bruising injuries, which leave the skin intact and may not be visible externally cause:

  • increased respiration rate and heat production
  • internal discoloration because of damaged tissues
  • off-flavours because of abnormal physiological reactions in damaged parts (*Applicable to non-leafy fruits and vegetables generally)

Further issues:

  • Does the presence/occurrence of browning indicate or coincide with McGee's off-flavors?
  • How does a plastic knife's lack of carbon relative to its dullness compare to a non-synthetic knife that is razor sharp?
  • What impact does a slicing motion (lacerating) have compared to a chopping motion (crushing)? Does friction cause more rupturing than pressure?

Caveats:

  • The majority of my experience does not rely on iceberg or other watery greens; in particular my advice is particularly suited to salads made with heartier greens ranging from spinach and romaine, to chard and kale.
  • Further, when preparing greens for a salad I do not do so too terribly far in advance; i.e. this advice may not suit use cases designed to preserve pre-cut greens indefinitely,
  • For salads being prepared promptly, tossing in lemon juice, vinegar, the vast majority of dressings, or any other acidulated liquid stems browning and oxidation prior to consumption; rendering the entire problem of browning moot
mfg
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  • "Uniform cuts will make the leaves into shapes their cellular structure doesn't support" <-- can you substantiate this claim somehow (as well as its corollary in the second list)? – Aaronut Jun 07 '12 at 00:13
  • @aaronut tissues tear in accordance with their weak points. These weak points, between cells, is called interstitial space. Far be it for me to claim any scientific authority (no sarcasm, honest disclaimer), but the McGee citation flies in the face of biological common sense. Why would tearing do more than incidental rupturing of cell walls; McGee seems to claim that you're ripping through only cells. – mfg Jun 07 '12 at 03:07
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    There's no such thing as "common sense" in science - that's why we *have* science. I don't have the book on hand, but I assume that McGee has citations and/or experimental data. In any case, the OP seems to be asking for some practical data as opposed to theoretical speculation. Even if we take the somewhat dubious claim about cellular structure at face value, that doesn't tell us much about the practical impact. – Aaronut Jun 07 '12 at 22:55
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    @aar We do have common sense in science, andit is given to simplest explanations (though occasionally undone by more complex ones); We prefer simpler theories to more complex ones "because their empirical content is greater; and because they are better testable" ([Popper](http://en.wikipedia.org/wiki/Occam's_razor#Karl_Popper)). – mfg Jun 08 '12 at 10:45
  • I do not mean to insinuate that McGee didn't research this, I just mean it flies in the face of my (admitted) rudimentary understanding of biological structure. Given to the taste for massaged greens, I find dubious the claim that bruising greens has such a substantial impact with "off-flavors" that it would entail some most-efficient-means of inducing the-least-possible-force. – mfg Jun 08 '12 at 10:45
  • The Cook's Illustrated article you linked claims browning occurs at the 12-14 day mark, with 12 days for normally cut lettuce, 13 for cut with plastic, and 14 for torn leaves. Given that lettuce is browning on the ribs before this, the difference between cut and torn is no longer important. – BobMcGee Jun 08 '12 at 23:38
  • @bob correct; I linked this as to illustrate the lack of practical implication of tearing versus cutting. I find tearing to be of no greater effort (easier in my experience for robust greens; chopping kale minus stem is a pain), though I think your reasoning is sound – mfg Jun 09 '12 at 04:24
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I think the biggest issue, what they're warning you against when they say not to cut, has to do with removing leaves if you're using less than a whole lettuce. If you slice up the lettuce head as though it was an eggplant, you will leave behind a flat plane of cut lettuce walls which will be nasty and brown the next time you make a salad. If you pull off leaves by hand, the rest of the lettuce will stay nicer.

I suspect for a salad you will eat within minutes, whether you now chop or tear the leaves you've pulled off won't matter much. If you're pulling one leaf, tearing it up, pulling another, tearing it up, deciding if you need more, then doing it al by hand is probably easier than switching back and forth to the knife. If you pull off half a lettuce, it's probably quicker to switch to a knife at this point and the experiments being reported seem to suggested there will be no harm in doing that.

Kate Gregory
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To the extent that tearing lettuce leaves more cells intact, if a salad is going to be served immediately, cutting is much better. The flavor of lettuce is in the juice, and cutting exposes the juices to the palate. There is nothing better that the sweet crunch of a rib of cut romaine lettuce. Torn lettuce tastes like paper by comparison.

P K Holt
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Lettuce is about one thing, nutrition. Many people have suggested that tearing lettuce significantly increases the amount of antioxidants. This benefit should trump any concerns about browning. https://www.veggie-quest.com/2013/07/rip-up-your-lettuce-quadruple-your/

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