The lemon (Citrus × limon) is a small evergreen tree native to Asia, and the tree’s ellipsoidal yellow fruit. The fruit’s juice, pulp and peel, especially the zest, are used as foods. The juice of the lemon is about 5% to 6% citric acid, which gives lemons a sour taste. The distinctive sour taste of lemon juice makes it a key ingredient in drinks and foods such as lemonade, cocktails and soft drinks.
Lemon juice is also used as a short-term preservative on certain foods that tend to oxidize and turn brown after being sliced, such as apples, bananas and avocados, where its acid denatures the enzymes that cause browning and degradation.