The Lemon, is a species of small evergreen tree in the flowering plant family Rutaceae, native to Asia. Lemons are a rich source of vitamin C, providing 64% of the Daily Value in a 100 g serving. Other essential nutrients, however, have insignificant content. Lemons were the primary commercial source of citric acid before the development of fermentation-based processes.
Lemon juice, rind, and zest are used in a wide variety of foods and drinks. Lemon juice is used to make lemonade, soft drinks, and cocktails. It is used in marinades for fish, where its acid neutralizes amines in fish by converting them into nonvolatile ammonium salts, and meat, where the acid partially hydrolyzes tough collagen fibers, tenderizing the meat, but the low pH denatures the proteins, causing them to dry out when cooked. The juice of the lemon is about 5% to 6% citric acid, which gives a sour taste. The distinctive sour taste of lemon juice makes it a key ingredient in drinks and foods such as lemonade and lemon meringue pie.