What are the main uses of citric acid

Citric acid is the largest organic acid soluble in water and is a natural preservative and food additive. Based on water content, it can be divided into citric acid monohydrate and citric acid anhydrous. Due to its physical properties, chemical properties and derivative properties, it is the most important organic acid widely used in food, medical, chemical and other industries. So, what are the specific functions and uses of citric acid?

1. Effect of citric acid

Citric acid is mainly used as an acidifying agent, solvent, buffer, antioxidant, deodorant, flavor enhancer, gelling agent, toner, etc. In addition, citric acid can also inhibit bacteria, protect color, improve taste. and promote the conversion of sucrose. Citric acid also has a chelating effect and can remove some harmful metals. Citric acid can prevent oxidation caused by enzymatic and metal catalysis, thereby preventing discoloration and flavor change in quick-frozen fruits.

2.Use of citric acid

A. For the food industry

Because citric acid has a mild and refreshing sour taste, from a food additive perspective, it is mainly used in carbonated drinks, fruit juice drinks, lactic acid drinks and other soft drinks and pickled foods, and its demand is affected by seasonal climate changes. Citric acid accounts for about 2/3 of the total acid flavor consumption. Adding citric acid to canned fruit can maintain or improve the taste of museum fruit, increase the acidity of some low-acid fruits (lower pH), weaken the heat resistance of microorganisms and inhibit their growth, and prevent bacteria from multiplying and killing low-acid canned fruits. Adding citric acid to candy as an acid is easy to coordinate with the fruit flavor. The use of citric acid in gel products, jams and jellies can effectively reduce the negative charge of pectin so that the hydrogen bond between pectin molecules can bond to the gel. When processing canned vegetables, some vegetables exhibit an alkaline reaction. Using citric acid as a pH adjuster can not only play a role in seasoning but also maintain its quality. Citric acid has chelating and pH-regulating properties that can enhance the effectiveness of antioxidants, inhibit enzyme activity, and extend food shelf life in frozen food processing.

Citric acid monohydrate is primarily used as an acidic flavoring agent in soft drinks, fruit juices, jams, fruit sugars, and preserves, and as an antioxidant in edible oils. At the same time, it can improve the sensory properties of food, increase appetite, and promote digestion and absorption of calcium and phosphorus in the body.

Anhydrous citric acid is widely used in spirits. Citric acid salts, such as calcium citrate and ferric citrate, are fortifiers that need to be added to some foods along with calcium and iron ions. Esters of citric acid, such as triethyl citrate, can be used as non-toxic plasticizers in the manufacture of plastic films for food packaging, and as an acid and preservative in the beverage and food industries.

B. For water treatment industry

Citric acid can sterilize and regulate the pH value of water when purifying water. The acidity of citric acid can change the pH value of cells and affect the normal metabolism of bacteria. High concentrations of acidic hydrogen ions can also alter the biological activity of bacteria and directly damage cells.

C.For chemical reagent and washing

Citric acid can be used as a chemical analysis reagent in chemical technology, as an experimental reagent, chromatographic analysis reagent and biochemical reagent; It is used as a complexing agent and masking agent to prepare a buffer solution.

The use of citric acid or citrate as a detergent auxiliary can improve the performance of detergents, rapidly precipitate metal ions, prevent the re-attachment of contaminants to fabric, maintain the necessary alkalinity for washing, disperse and suspend dirt and ash, and improve performance. surfactants.

Citric acid can also be made into a formaldehyde-free anti-crease agent for finishing clean cotton fabrics.

D.For cosmetics

Citric acid can prevent and eliminate skin pigmentation. Citric acid is a type of fruit acid that is mainly used to speed up cutin renewal and is commonly used in lotions, creams, shampoos, whitening products, anti-aging products, acne products, etc. Cutin renewal is beneficial for skin melanin peeling, thinning pores, dissolving blackheads, etc.

E. To protect the environment

China is rich in coal resources, which make up the bulk of its energy. However, there was no effective technology for flue gas desulphurization, which resulted in severe SO2 pollution of the atmosphere. Currently, China's annual SO2 emissions have reached nearly 40 million tons. There is an urgent need to explore effective desulfurization technology. With low vapor pressure, non-toxicity, stable chemical properties and high SO2 absorption rate, citric acid sodium citrate buffer solution is a desulfurizing absorbent of great development value.

F. For livestock additives

Adding citric acid to piglet feed can speed up weaning, improve feed utilization by 5-10% and increase litter size in sows. Adding 1-2% citric acid to the diet of grower and finisher pigs can increase daily gain, reduce feed-to-meat ratios, improve protein digestibility, reduce backfat thickness, improve meat quality and carcass characteristics.

D. For sterilization

The combined action of citric acid and 80 degrees has a good effect on the destruction of bacterial spores and can effectively kill bacterial spores contaminated in the hemodialysis machine pipeline. Lemon, which enjoys a reputation as the “king of Western food”, has a strong bactericidal effect and is beneficial for food hygiene. Apart from the aroma of lemon, people have always loved to use it to prepare cold dishes. Not only is it tasty and refreshing, but it can also improve your appetite, such as the recently very popular “chicken legs with lemon.”

H. For medicine

Citric acid, also known as citric acid, must have calcium ions during the formation of the prothrombin activator and the subsequent coagulation process. Citrate ion and calcium ion can form a soluble complex that is difficult to dissociate, thereby reducing the concentration of calcium ion in the blood and preventing blood clotting. It is used as an in vitro anticoagulant in blood transfusions or anticoagulation of laboratory blood samples.

3. Precautions

A. Industrial hazards

Health hazard: concentrated citric acid solution is irritating to the mucous membrane. When used industrially, contact may cause eczema;

Explosion Hazard: Citric acid is highly flammable. Powder and air may form an explosive mixture which may cause fire and explosion if exposed to open flame, high temperature or contact with an oxidizing agent.

B. Storage conditions

Citric acid monohydrate loses its crystalline water in dry air or when heated to about 40 degrees, and evaporates slightly in humid air. A dilute aqueous solution of citric acid can ferment at rest. Therefore, solid monohydrates or anhydrous substances should be stored in airtight containers in a cool, dry place.