Why They Brown

• Within about 30 minutes of slicing, a Granny Smith apple's flesh begins to turn brown. This happens when an enzyme in the apple, called polyphenol oxidase, is loosened and comes in contact with air. The polyphenols undergo a chemical reaction, one effect of which is a change in color and appearance. The official scientific name for this reaction is enzymatic browning.

Acid Solution

• Acid slows the chemical process that causes browning. All it takes is a spritz or two of vinegar or lemon juice to prevent your Granny Smith's from turning. Mix up a solution with a ratio of 1 tablespoon of juice or vinegar to 1 cup water. Immerse the apple slices in the water and drain when ready to use.

Other Acidifiers

• If you'd rather not use vinegar or lemon juice, opt for any juice high in vitamin C, such as pineapple or lime. Pineapple juice may add a sweeter flavor to the already tart Granny Smiths. You could also crush ascorbic acid, or vitamin C, tablets into water to use to prevent the apple from browning. Clear soda also contains acid that preserves the color of your apple slices.

Alternatives to Soaking

• Put the acidified solution in a mister bottle and spritz the slices lightly as an alternative to soaking. Another option is to not use acidified water at all, but to limit the exposure of the cut slices to the air. Cut lengthwise slices in the apple, but avoid cutting all the way into the core so the slices stay adhered. Wrap a rubber band around the cut apple to keep them tightly bound together and minimize exposure to the air. When you're ready to eat, remove the rubber band and pull off the prepared slices.