Those packages of pre-sliced apples you can buy at store are great for a healthy snack on the go but the price can add up. Make your own by slicing apples, soak in cold water for 3-5 minutes, then soak in a lemon-lime carbonated soda (such as 7-up or sprite) for 3-5 minutes. Divide into snack size portions and store in Ziploc bags in the fridge. The lemon-lime soda will keep the apples from browning and make them last longer. Source.