Have you ever wanted to do some kitchen prep early so that you don’t have as much to do later? Cutting up apples too early doesn’t usually work, as they turn brown when exposed to air. Something about oxidation. Harold McGee’s book, On Food and Cooking, has a much loftier explanation if you’re interested in the science behind it.
I have found that placing the cut apples in a bowl of cold water, spiked with just a touch of lemon juice will work just fine for a few hours (4 hours max.). Any more than that, the apples start to absorb too much water and become waterlogged.
A scant 1/2 teaspoon of lemon juice per cup of water is plenty. If you add too much lemon, the apples will either start to break down (especially if you leave them in too long) or take on an acid flavor, not a nice lemon flavor.
Once I place my cut apples in the lemon-tinged water, I cover the surface with a piece of parchment to keep the apples submerged, and I place the bowl in the fridge to keep them cold. Once I’m ready to use them in a recipe, I drain them and pat them dry with a paper towel. This little trick also works for pears. Of course, if you’re cooking the apples, like in the Spicy Apple Chutney recipe this month, you don’t need to worry about your apples turning a little brown, although, I still wouldn’t dice them up and leave them on the counter for hours before you make the chutney.