Citric acid, also known as citric acid, is an important organic acid. It is a colorless crystal, odorless, has a strong sour taste, and is easily soluble in water. , is a natural preservative and food additive. Synthetic citric acid is produced by fermenting sugar, molasses, starch, grapes and other sugar-containing substances. It can be divided into two types: anhydrous and hydrated. Pure citric acid is colorless transparent crystal or white powder, odorless and has an attractive sour taste. The translucent colorless crystals obtained from hot concentrated aqueous solutions are anhydrous and have a melting point of 153°C. The translucent colorless crystal obtained from cold water solution is monohydrate with a density of 1.542. It softens at 75℃ and melts at about 100℃.
Citric acid is widely distributed in nature:
Anhydrous citric acid is a natural component and an intermediate product of physiological metabolism in animals and plants. It is also one of the most widely used organic acids in food, medicine, chemical industry and other fields. It exists in plants such as lemons, citrus, pineapples, gooseberries, raspberries, grape juice and other fruits, and in the bones, muscles, and blood of animals.
Many types of fruits and vegetables, especially citrus fruits, contain large amounts of citric acid, especially lemons and limes – they contain large amounts of citric acid. Citric acid, after drying, can reach 8% content (approximately 47g/L in juice). In citrus fruits, the content of citric acid ranges from 0.005 mol/L in oranges and grapes to 0.30 mol/L in lemons and limes. This content varies with different cultivars and plant growth conditions.