oxidation.
the oxygen in air reacts with the surface of the newly cut lettuce and turns it brown.. i think the surface of the knife can have a small layer of oxidation on it too, so that can affect the lettuce as well or at least that's what i think happens....... you can get plastic lettuce knives....
Most fruits and vegetables have two chemicals called enzymes and poly-phenols. When these two chemicals combine, they "oxidizes" which turns fruits and vegetables brown. These two chemicals are usually separated by a cell wall which breaks down over time, but cutting and tearing can damage these cell walls causing browning at the edges.
Usually metal knives are thought to brown lettuce faster then tearing or using plastic lettuce knives though there is very little support for this. Either method will cause browning, and lettuce is usually consumed quickly after being cut thus browning is not an issue.
The lettuce does not turn brown due to it being cut with a metal knife. It turns brown due to oxidation.
Not as far as nutritional value. Lettuce that is torn doesn't turn brown as fast though.
It is actually better to tear lettuce than it is to cut it, especially if you want it to stay fresh. Cutting lettuce makes it turn brown and wilt faster then it does when you tear it. But if you do cut it use a sharp knife because that will keep the edges clean, instead of being ragged. Also the metal in the knife causes a reaction that will make it wilt and go bad.
To prevent lettuce from browning after cutting, use a sharp knife to make clean cuts instead of tearing or using a dull knife. Additionally, you can soak the cut edges in cold water or immediately place the lettuce in a bowl of ice water to minimize exposure to air. Applying a small amount of lemon juice or vinegar on the cut edges can also help slow down the browning process. Finally, store the cut lettuce in an airtight container in the refrigerator to keep it fresh longer.
Like lettuce, if you cut mushrooms with a stainless steel knife the cut edges tend to brown or discolor. They are also delicate so when cutting through thicker pieces bruising may occur.
To remove the brown ends of lettuce after slicing, use a sharp knife to trim away the discolored edges carefully. Alternatively, you can also use kitchen scissors to snip off the brown parts. Ensure that the remaining lettuce is clean and fresh for use. Rinse the cut pieces briefly under cold water to maintain crispness before serving or storing.
* Yes, you should rip the lettuce because the metals in a knife blade will react with the lettuce and cause oxidation, which will speed the browning of the lettuce. If the lettuce is to be used right away, then cutting with a knife is fine; but if not, then tearing is the best method. * People rip lettuce because a stupid salad-dressing commercial from the '70s said to do so. There is no good reason to rip vs cut. The answer above is incorrect: Some knives do what it says they do, and others do not. Oxidation occurs whether you rip or cut. For lettuce, it does not speed browning. Test it yourself. * The previous answer is incorrect: Metal knives do cause oxidation of lettuce and other vegetables. There are specially made serrated plastic knives for cutting lettuce. If you don't wish to purchase one of these knives, the best method is to tear your lettuce. == ==
You just cut that leaf off, hope it helped! X
no they will not turn brown
Iceberg lettuce changes color because of enzymes. When lettuce is cut, enzymes from cells are released. One enzyme, polyphenoloxidase, reacts with polyphenol molecules in the lettuce, forming brown pigments.
To cut romaine lettuce for salad, start by washing and drying the leaves. Then, chop the lettuce into bite-sized pieces using a sharp knife. Avoid tearing the leaves to maintain a crisp texture. Finally, toss the chopped lettuce with other salad ingredients for a well-balanced presentation.
Because your cutting it open and as you do that the juice comes out and they come out with that but it doesn't have a huge amount of them