Why Does Lettuce Turn Brown?

Answer

Lettuce turns brown because of a chemical reaction to oxygen. This reaction is called enzyme-catalyzed oxidation. The enzyme reaction produces quinones that lettuce to turn brown when in contact with oxygen.
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Q&A Related to "Why Does Lettuce Turn Brown?"
Lettuce turns brown when it goes bad and rotten because air traps odors and bad air that makes it go bad and stuff.
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Cutting lettuce with a metal knife causes the produce to turn reddish-brown in color. The carbon in a metal knife reacts with the lettuce enzymes and causes oxidation to occur. The
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Actually, it's not the metal that does it. What happens is any cutting will cut cells,
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Guacamole turns brown due to what is known as enzymatic browning. Enzymatic browning results in the production of melanins, the same chemicals that provide the pigment in human skin
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1 Additional Answer
It turns brown from cutting it with a knife. Lettuce should always be torn or they make some special lettuce cutters that are made of plastic.
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