Lemon is a valuable citrus fruit, and is highly appreciated for its juice that contains approximately 5 percent citric acid, which imparts it a sour taste. In fact, this fruit was a prime source for extraction of this acid, particularly before the advent of fermentation process. It is used for cooking, baking, and other non-culinary purposes. Other products like lemon oil, pulp, and zest are also used for a wide range of applications.