You know when you have to use fresh apples without cooking them ( Apple salad) and they just turn brown in two seconds? Well I have a solution for you! :)
In a medium bowl (or a big bowl if you are using a lot of apples) put water (about half of your bowl) and the juice of a lemon. Slice or cut your apples and put them in the water right away.
You can also just dip them in lemon juice but I find that the acid taste of lemon juice takes over the apple taste.
The acidity from the lemon and the lack of oxygen from being in the water will keep the apples from browning! :)Picture from : http://www.flickr.com/photos/themarmot/61806863/sizes/o/in/photostream/