Apple and Pears are great fruits due to their benefit to the mankind. However, their market value comes down because they tend to go stale when we cut them and keep for later on use.
Normally if the Apple and Pears are uncut, you can refrigerate them for later use. However, if you cut them then it is important do something to save them. Lemon juice keeps the fruit fresh. Because it is full of ascorbic acid and has a lot PH. Thus, when the cut apple is exposed to oxygen, the oxygen reacts with ascorbic acid and it will take longer for the apple to turn brown.
You can also use lime juice and cranberry juice fruit. Grape juice and grapefruit juice have a low PH and is helpful in reducing PH.