Welcome to brain Stuff from how Stuff Works dot com where smart Happens. Hi. I'm Marshall Brain with today's question, why do apples and potatoes turn brown when you slice them? And how do you keep them from turning brown? All cells, whether they're bacteria cells, human cells, or apple cells, contain thousands of enzymes. These enzymes do all the work necessary for the cell to live its life. Once you cut
the fruit, you open up some of the cells. One of the enzymes inside the cell, tyrosinees, now has access to oxygen in the air, and it does its thing, turning the fruit brown. This is the same thing that causes brown spots and apples when you drop them. The easiest way to prevent the browning is to put the sliced apples in water so that the enzyme doesn't have access to oxygen. You can also heat the apples to the nature the enzyme, or lemon juice also inactivates the enzyme.
In humans, tyrosine is also important because it helps create melanin, which causes tanning. The lack of tyrosenes in humans leads to albinism. So in humans, the browning that tyrozenes causes is actually a good Thing. Do you have any ideas or suggestions for this podcast? If so, please send me an email at podcast at how stuff works dot com. For more on this and thousands of other topics, go to how stuff works dot com