All Unitasker Wednesday posts are for entertainment — we don’t want you to buy these items, we want you to laugh at their ridiculousness. Enjoy!
Growing up, my mom had a giant green plastic knife that she kept in our family’s kitchen tool drawer. When I got my first apartment, she asked me if I wanted it. Seeing as I had no idea what the knife did since I’d never seen her use it, I had to ask her why I could possibly want to take it with me. She informed me it was a “lettuce knife” for the purpose of cutting lettuce. Apparently, she continued, it also prevented lettuce from browning when/if you cut it. The lettuce knife looked similar to this:
A couple weeks ago, I randomly started thinking about that knife and how strange it was. It reminded me of a movie or play prop, not something you would actually use in a kitchen.
I researched what a couple of the most trusted food scientists today had to say on the matter of traditional knives causing lettuce to brown to see if they were true.
Harold McGee in his book On Food and Cooking on page 318 strongly suggests to use a regular knife to cut lettuce:
If the leaves need to 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-flavors and darkened patches. Cutting with a sharp knife is generally the most effective method; tearing by hand requires squeezing, which may damage tender leaves.
Since the plastic lettuce knives are about as sharp as a plastic knife you might use at a picnic (which isn’t sharp at all) and they can’t be sharpened, this excludes the lettuce knife as a possible tool to keep lettuce from browning. (His statement also dismisses tearing leaves as a viable method to prevent browning.)
The magazine Cook’s Illustrated studied lettuce in their test kitchen for more than two weeks and came to a different conclusion than McGee, but it’s hardly an endorsement for buying a lettuce knife just to cut lettuce. They used a stainless steel blade (one with a super-thin high-carbon steel blade), the Zyliss Fresh Cut Salad Knife, and tore some, too:
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.
In short, the test kitchen discovered that lettuce naturally browns by 10 days, making the methods for cutting or tearing pointless since the cut/torn edges didn’t brown until a couple days later. As I said, it’s hardly an endorsement to buy a special knife.
My guess is that most people don’t keep lettuces in their refrigerators for more than 10 days, especially since they can’t be frozen. People buy lettuce and use it in a week. If you are someone who does keep lettuce for more than 10 days, the lettuce will already be brown, so using a plastic lettuce knife won’t matter.
For best results when cutting lettuce, use a very sharp, very thin, stainless steel blade and then plan to consume the lettuce immediately or up to 10 days after purchase. If you plan to cut it and store it, be sure to buy the freshest lettuce you can so as to make it those full 10 days (if the lettuce is old, it won’t even last 10 days before browning). You can also tear lettuce with your hands if you plan to use it right away, not dirtying any knives at all.
Knowing how to use and care for the knives you already own will save you from spending money on specialty tools you don’t need, especially when the specialty tools don’t improve or benefit your desired outcome.