Citric acid monohydrate: a versatile organic compound

Citric acid appears as colorless translucent crystals or white granules or white crystalline powder, odorless, and extremely sour. It is slightly deliquescent in humid air. Citric acid crystallizes from hot water as an anhydrous substance; it crystallizes in cold water as a monohydrate. When heated to 78°C, the monohydrate decomposes into anhydrous substances.

Properties

It often contains 1 molecule of crystal water, i.e. citric acid monohydrate, which is odorless, extremely sour, and soluble in water, alcohol, and ether.

Anhydrous citric acid can be obtained by controlling the appropriate temperature during crystallization.

The aqueous solution is acidic. It has a slight weathering effect in dry air and deliquesces in humid air. It decomposes above 175°C, releasing water and carbon dioxide.

Natural existence

Natural citric acid is widely distributed in nature. Natural citric acid exists in lemons, citrus fruits, pineapples and other plant fruits and in the bones, muscles and blood of animals. Synthetic citric acid is fermented from sugar, molasses, starch, grapes and other sugar-containing substances, and can be divided into anhydrous and hydrated. Pure citric acid is a colorless, transparent crystal or white powder, odorless, with an attractive sour taste.

Many fruits and vegetables, especially citrus fruits, contain more citric acid, especially lemons and limes - they have a lot of citric acid content, which can reach 8% after drying (about 47g/L in juice). In citrus fruits, the citric acid content ranges from 0.005mol/L in oranges and grapes to 0.30mol/L in lemons and limes. This content varies with different cultivars and plant growth conditions.

Product Application

1. Citric acid monohydrate is used as an acidifier, acidity regulator, flavoring agent, preservative, and preservative in the food and beverage industry.

2. Citric acid monohydrate can be used as an antioxidant, plasticizer, and detergent in the chemical industry, cosmetics industry, and washing industry.

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