Citric acid is an important organic acid, colorless crystal, often contains a molecule of crystalline water, odorless, has a strong sour taste, easily soluble in water. Its calcium salts are more soluble in cold water than hot water, and this property is often used to identify and separate citric acid.
When citric acid crystallizes from hot water, no hydrate is formed. When crystallized in cold water, monohydrate is formed. When heated to 78 °C, the monohydrate breaks down to no hydrate. Citric acid can also be dissolved in anhydrous ethanol at 15 degrees Celsius.
Citric acid is the first major organic acid, due to physical properties, chemical properties, derivative properties. This type of inorganic salts is widely used in food, medicine, daily chemical and other industries of the most important organic acid.
Used in food industry
Because citric acid has a mild and refreshing sour taste, it is widely used in the manufacture of various beverages, soda, wine, candy, snacks, biscuits, canned juice, dairy products and other foods. In all the organic acid market, citric acid market share of more than 70%, so far there is no one can replace the acid flavor agent. Citric acid in a molecule of crystalline water is mainly used as an acidic flavoring agent for refreshing drinks, fruit juices, jams, fruit drops and cans, and can also be used as an antioxidant for cooking oil. At the same time improve the sensory properties of food, enhance appetite and promote the digestion and absorption of calcium and phosphorus in the body. Anhydrous citric acid is used in large quantities in solid beverages. Citric acid salts such as calcium citrate and iron citrate are fortifiers that require the addition of calcium and iron ions to some foods. The ester of citric acid such as triethyl citrate can be used as a non-toxic plasticizer, the manufacture of plastic film for food packaging, and the acid agent for the beverage and food industry.
Used in chemical, pharmaceutical and textile industries.
Citric acid can be used as chemical analysis reagent in chemical technology, used as experimental reagent, chromatographic analysis reagent and biochemical reagent; Used as a complexing agent, masking agent; To prepare buffer solution. The use of citric acid or citrate as washing aid can improve the performance of washing products, can quickly precipitate metal ions, prevent pollutants from reattaching to the fabric, and maintain the necessary alkaline washing; Dispersion and suspension of dirt and ash; It can improve the performance of surfactants and is an excellent chelating agent. It can be used as a reagent to test the acid resistance of building ceramic tiles.
The formaldehyde pollution of clothing is already a very sensitive problem. Citric acid and modified citric acid can be made into a formaldehyde-free anti-wrinkle straightening agent, which is used for the anti-wrinkle finishing of pure cotton fabrics. Not only anti-wrinkle effect is good, but also low cost.
For environmental protection
Citric acid - Sodium citrate buffer is used for flue gas desulfurization. China is rich in coal resources, is the main part of energy, but the lack of effective flue gas desulphurization technology, resulting in serious atmospheric SO2 pollution. At present, China's annual SO2 emissions have been nearly 40 million tons, research effective desulfurization process, is a top priority. Citric acid-sodium citrate buffer solution is a very valuable desulphurization absorber because of its low vapor pressure, non-toxic, stable chemical properties and high SO2 absorption rate.
For livestock production
Adding citric acid to piglet feed can lead to early weaning, increase feed utilization rate by 5% to 10%, and increase sow litter yield. Adding 1% ~ 2% citric acid to the diet of growing-finishing pigs can increase daily gain, decrease feed to meat ratio, increase protein digestibility, reduce back fat thickness, and improve meat quality and carcass characteristics. Rare earth citrate is a new high-efficiency feed additive, suitable for pig, chicken, fish, shrimp, cattle, sheep, rabbits, silkworms and other animals, with the characteristics of promoting animal growth, improving product quality, improving disease resistance and survival rate, improving feed conversion rate, shortening feeding cycle.
Use in cosmetics
Citric acid is a kind of fruit acid, the main function is to speed up the keratin renewal, often used in lotions, creams, shampoos, whitening products, anti-aging products, acne products and so on. The renewal of the keratin helps to peel off the melanin of the skin, narrow the pores, and dissolve the blackhead. For example, Biotherm Hydra Soothing Cleansing Mousse leaves skin soft and comfortable, with a fresh, pure complexion.
Used to kill bacteria
The combination of citric acid and 80℃ temperature has a good effect on killing bacterial spores, and can effectively kill contaminated bacterial spores in the blood dialysis machine pipeline. Enjoying the reputation of "the king of Western food", lemon has a strong bactericidal effect and is very good for food hygiene. Coupled with the fresh smell of lemon, people have always liked to use it to make cold dishes, which is not only delicious and refreshing, but also can increase appetite.
Used in medicine
Calcium must be involved in the formation of prothrombin activators and subsequent coagulation. Citrate ion and calcium ion can form a soluble complex which is difficult to dissociate, thus reducing the concentration of calcium ion in the blood and preventing blood coagulation. This product is used as an in vitro anticoagulant during blood transfusion or anticoagulation of laboratory blood samples.
