Citric acid is a fruit acid that has a variety of roles and uses. In the food industry, citric acid is often used as a flavoring agent to increase the acidity of food and improve taste. In addition, citric acid is also used as a preservative, which can inhibit bacterial growth and improve the color stability of food, thereby extending the shelf life of food. Citric acid also plays an important role in the cosmetics industry. It acts as a gentle cleanser to help remove dirt and oil from the surface of the skin, leaving the skin fine and smooth. In addition, citric acid can also soften the cuticle to a certain extent and improve the problem of rough skin.