01 September, 2011
Citric Acid in Apple Browning
Keeping apple slices ready in the refrigerator is an easy way to encourage the whole family to eat more fruit. While you can purchase cut apple slices, cutting your own is far more economical. Unfortunately, when apple slices are exposed to air, they quickly turn an unappetizing shade of brown and lose valuable vitamin C. Several solutions, including those made with citric acid, help you preserve and enjoy cut apples.
Apples and other fruits, like pears and peaches, turn brown within just a few minutes of cutting them. This chemical reaction is called enzymatic browning. The responsible enzyme, polyphenol oxidase, has to be neutralized by an acidic solution if you wish to preserve the color in your canned, frozen or fresh cut apples. The acid will neutralize the enzymes that turn the fruit brown when exposed to oxygen.
Citric acid can be purchased at drug stores and some supermarkets. If you're shopping at the supermarket, look for a product labeled sour salt, which is typically sold with kosher foods. To keep cut apple slices from browning, dissolve 3 tbsp. of citric acid in one cup of water. Dip each apple slice in the citric acid solution.
If you cannot locate citric acid or would prefer a product designed to prevent browning, you will find several on store shelves. Often stocked alongside canning products, these powders typically contain either citric acid or ascorbic acid, along with sugar and an anti-caking agent. These products work well, but are more expensive than using citric acid alone.
There are several homemade alternatives to citric acid powder or commercial fruit preservatives. You can soak cut apples in a solution of 1/2 cup bottled or fresh lemon juice and 1/2 gallon of water. Ginger ale or lemon lime soda may also be used. Allow the apple slices to soak for ten minutes. As an alternative, ascorbic acid powder or tablets, sold as pure vitamin C, will eliminate browning. Use 3 tsp. of ascorbic acid per cup of water to preserve apple slices.
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