1, used in food industry; Because of its mild and refreshing sour taste, citric acid is widely used to make various drinks, soda, wine, candy, snacks, biscuits, canned fruit juice, dairy products and other foods. In all organic acid markets, the market share of citric acid is above 70%, and so far there is no sour agent that can replace citric acid. One molecule of crystal water citric acid is mainly used as an acidic flavoring agent for refreshing drinks, fruit juice, jam, fruit candy and canned food, and can also be used as an antioxidant for edible oil.

2. Used in chemical industry and textile industry: citric acid can be used as a reagent for chemical analysis in chemical technology, as an experimental reagent, a chromatographic analysis reagent and a biochemical reagent; Used as complexing agent and masking agent; Used to prepare buffer solution. Using citric acid or citrate as builder can improve the performance of washing products, quickly precipitate metal ions, prevent pollutants from reattaching to fabrics, and maintain the alkalinity necessary for washing; Disperse and suspend dust and ashes; It is an excellent chelating agent to improve the performance of surfactants.

3, used in cosmetics: citric acid is a kind of fruit acid, its main function is to speed up keratin renewal, and it is often used in lotions, creams, shampoos, whitening products, anti-aging products, acne products, etc. The renewal of keratin contributes to the shedding of melanin, the shrinking of pores and the dissolution of blackheads.

4. Used for sterilization: citric acid and the temperature of 80℃ have a good killing effect on bacterial spores, which can effectively kill contaminated bacterial spores in the pipeline of hemodialysis machine. Lemon, which enjoys the reputation of "king of western food", has a strong bactericidal effect and is very beneficial to food hygiene. In addition, people always like to make cold dishes with lemons, which are not only delicious and refreshing, but also stimulate appetite.

5. Used in medicine: In the formation of prothrombin activator and the subsequent coagulation process, calcium ions must participate. Citrate ion and calcium ion can form a soluble complex which is difficult to dissociate, thus reducing the concentration of calcium ion in blood and blocking blood coagulation. This product is used as an anticoagulant in vitro when blood transfusion or laboratory blood samples are anticoagulated.

6. Chemical processing or deep processing of citric acid: In addition to the above-mentioned uses of citric acid itself, another main use of citric acid is deep processing, which is a colorful industrial chain.

At room temperature, citric acid is colorless and translucent crystal, white particles or white crystalline powder, odorless and extremely acidic, and slightly deliquescent in humid air. It can exist in the form of anhydrate or monohydrate: when citric acid crystallizes from hot water, it forms anhydrate; Crystallization in cold water produces monohydrate. When heated to 78℃, monohydrate will decompose into anhydrate. Citric acid can also be dissolved in anhydrous ethanol at 65438 05 degrees Celsius.

The crystal morphology of citric acid varies with crystallization conditions, including anhydrous citric acid C6H8O7 and citric acid C2H8O7. H2O，2C6H8O7。 H2O or C6H8O7.2H2O and crystal water.

References:

Baidu encyclopedia-citric acid