Kitchen Myths

Facts and fiction about food and cooking, by Peter Aitken

You must use a serrated knife to slice ripe tomatoes

You certainly can use a serrated knife for ripe tomatoes, but there’s no need to. If you find yourself always turning to a serrated knife for this task it is probably because your straight-edged knives are not sharp enough. A well-sharpened regular knife will make paper-thin slices from a ripe tomato—in fact, some people use this as a test for a knife’s sharpness.

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13 responses to “You must use a serrated knife to slice ripe tomatoes

  1. Ivan July 20, 2011 at 4:27 am

    Bull, a tomato skin will blunt a flat-bladed knife that is why you need a serrated knife. Cut enough tomatoes in a professional situation and you’ll understand

  2. kitchenmyths July 20, 2011 at 10:01 am

    I’m afraid you didn’t understand the original post. I don’t know about tomato skin dulling knives, it has not been my experience – but then again, I have never sliced tomatoes in huge amounts. My point was that a sharp non-serrated knife will slice tomatoes perfectly well, that’s all.

  3. Ivan July 22, 2011 at 6:55 am

    And my point is that if you use a flat bladed knife, you won’t have much of a knife left after a while which will not happen if you use a serrated knife

  4. Dane July 22, 2011 at 6:50 pm

    Some facts to support your claim would be nice, Ivan. What is it that dulls the blade? The blade is (supposedly) steel and tomato is rather much softer than that. Stainless is pretty resistant to acids as well. Of course you need to hone your blade occasionally, but that’s true with all straight blades no matter what you’re cutting. And why doesn’t this mystery dulling happen with a serrated blade? Facts, please, since we’re doing mythbusting here.

  5. Ivan August 11, 2011 at 4:14 am

    I can’t quote material science but just professional knowledge. It’s to do with the extra smoothness of the tomato skin versus the smoothness of the flat blade. I would hypothesize that when two flat edges meet they both wear each other down, where as the serration tears the skin of the tomato. The New Scientist’s ‘Why don’t penguins feet freeze’ and other similar publications fields similar questions, perhaps an email to them may be able to give you a more scientific explanation

    • John May 7, 2016 at 6:58 pm

      That is why you touch a good knife up on a steel , smoothness of a tomato skin? a lot of foods in cooking have smooth skins so that theory is not that hypothesis is incorrect if you could come back with scientific proof please

  6. Ivan August 11, 2011 at 4:22 am

    oh and just to back-up my statement. Have you ever seen a shark or other carnivore with flat teeth?

  7. kitchenmyths August 11, 2011 at 11:57 am

    The only reason I can think of that tomato skin would dull a knife is if the skin contained some sort of abrasive substance that would quickly wear the edge down. A web search found no suggestion of this. And, as Dane says, if this dulling occurs it would dull a serrated knife too. I am not sure the carnivore example is relevant because carnivores don’t eat tomatoes!

  8. coffeerocks September 28, 2011 at 4:54 pm

    I use a high end Japanese knife in the kitchen. I cut lots of tomatoes. It does just fine and it doesn’t seem to dull it any more than normal use.

  9. Adam Weber November 9, 2011 at 6:40 am

    Hi all,
    What Ivan said is true (as any chef or ‘knife-knut’ will tell you…) It doesn’t affect modern stainless steel to QUITE the same extent as it did in the days of carbon-steel-only knives, but it is still significant. Acidic fruits and veges were famous for literally ‘eating away the edges’ of steel blades! Trying to *restore* a nice, polished edge with a “butchers’ steel” didn’t really help, once that had happened and it meant the knives required more frequent grinding and honing, hence, didn’t last very long…maybe Ivan is as old as I am!
    About 30 years ago, I saw a demo from a guy who was selling complete sets of “cooks’ knives” for $25. Once in a while he’d offer the first ten suckers…erm…customers…TWO sets for the price of one! He would cut a leather shoe (with a rubber sole) in half, with 4-5 easy motions and then make perfect slices of a rather squishy-looking tomato with the same knife!
    The fact is, the knives WERE serrated, at the ‘micro-level’! They had obviously been ‘sharpened’ (‘GROUND’ is a more more appropriate term) with a coarse (#180-380 grit) stone, making the so-called ‘knives’ into saws! A TRULY sharp, polished knife-edge would bend and then glide right off the surface of shoe leather (or a tomato’s skin!)
    Most cooks’ knives in Japan are sharpened with water-stones at #1000 grit, which is still very ‘rough’…because “micro-saws” are actually BEST in the kitchen! Japanese sashimi/sushi knives will always cut better than the average western knife, even when blunt, because of the blade design, which gives them an ‘included angle’ of about 25°, half that of the typical knife you’ll buy from (almost) any western cutlery supplier…they have great cutting ability, but several disadvantages, as well…but that’s another discussion!
    Best,
    Adam

    • kitchenmyths November 9, 2011 at 8:22 am

      Thanks for the interesting post, but I am afraid I must disagree. The stainless steel used in modern knives is totally impervious to any acid you would find in food, so the edge degradation you might see in a carbon steel knife with acid foods is simply not an issue. And yes, any knife is “serrated” at the microscopic level, and that’s what we want for a kitchen knife, but surely it’s clear that’s not what “serrated” means in the original post. I sharpen my knives to either 320 or 600 (US grit system) and my preferred sharpness test is for the knife to cleanly slice a ripe tomato using just its own weight.

  10. Pingback: How to Slice Tomatoes - If You Can Read, You Can Cook

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