This afternoon, for a school party, we served molten caramel and apple wedges. Knowing that they would be exposed to air for a considerable amount of time, we felt we needed to treat the apples to minimize browning. Many fruits and vegetables have a class of enzymes in them called peroxidases. These enzymes are designed to break down oxygen particles that can react with tissue and destroy it. As part of the process, the tissue often turns brown. This enzyme is the reason potatoes turn brown when cut open as well as the reason apples turn brown.
Knowing that browning is caused by an enzyme, we can prevent browning by preventing the enzyme from working. Discussed in this article are 5 easy ways to keep apples (or any vegetable) from turning brown.
1. Choose apples that are less prone to browning. Green Apples tend to brown far less than your conventional red delicious while Arangeh apples will brown the least of all. In general, color is a good indication of browning with red browning the most, yellow browning moderate, and green browning the least.
2. Keep apples under water. If you cut your apples under water, or leave them covered in water, you can reduce the amount of browning. While this does not reduce the activity of the enzyme that causes browning, the apple is exposed to less free oxygen while in water, thus reducing the amount of browning that occurs, and unlike potatoes, your water is not going to turn a dark brown in a few hours.
3. Brush the exposed apple with an acid. The peroxidase enzymes cannot function at low pH. The more acidic the environment, the more difficult it is for the enzyme to function. One of the easiest ways is to brush the apples with some lemon juice though this will impart some flavor to your apples. Alternatively, dissolve some citric acid (AKA vitamin c) in water and brush that on. It will accomplish the same thing as lemon juice but impart little to no flavor. Also, if you don't want your apples to be sour, brush them instead with pop (7-up, sprite, ginger ale). The low pH of the carbonated drink will keep down enzyme activity while sweetening your apples.
4. Blanch your apples. Blanching is when you drop the apples into boiling water for a short period of time. The high temperature will inactivate the enzyme so it no longer functions. Blanching will soften your apples as they begin to cook but, and your home may begin to smell like a warm apple pie, but if you do it for only a short time, softening is minimal and you only need to heat the outside where the enzyme is exposed to the air.
5. Wrap your apples tightly in plastic wrap. As we have said before, in order to turn brown, the enzyme in your apples needs to be exposed to oxygen. If you cover the skin in wrap, the apples are less exposed to oxygen and will brown less, but for this to work, the wrap needs to be touching the exposed surface.
Next time you have a gathering with apples and you want to keep them looking fresh and inviting all the time, use any one of these methods and they are sure to look in top shape.
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