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 and lemon meringue pie.
Lemon oil may be used in aromatherapy. Lemon oil aroma does not influence the human immune system, but may enhance mood. The low pH of juice makes it antibacterial, and in India, the lemon is used in Indian traditional medicines (Siddha medicine and Ayurveda).