What are the functions and uses of citric acid and in what fields? Is it dangerous to eat? Read the article to learn about citric acid.

Citric acid (CA), also known as citric acid, with the molecular formula of C ₆ h ₈ o ₇, is an important organic acid. It is colorless crystal, odorless, has a strong sour taste and is easily soluble in water. It is a natural preservative and food additive.
Natural citric acid is widely distributed in nature. Natural citric acid exists in plants such as lemon, citrus, pineapple and animal bones, muscles and blood. Synthetic citric acid is produced by fermentation of sugary substances such as granulated sugar, molasses, starch and grapes.
Many kinds of fruits and vegetables, especially citrus fruits, contain more citric acid, especially lemon and lime – they contain a lot of citric acid, which can reach 8% after drying (about 47g / L in fruit juice). In citrus fruits, the content of citric acid is between 0.005mol/l of orange and grape and 0.30mol/l of lemon and lime. This content varies with the growth of different cultivated species and plants.

Food hazard

Citric acid is an edible acid, which can enhance the normal metabolism in the body, and the appropriate dose is harmless to the human body. Adding citric acid to some foods tastes good and can promote appetite. Citric acid is allowed to be used in jam, beverages, cans and candy in China. Although citric acid does no direct harm to the human body, it can promote the excretion and deposition of calcium in the body. For example, long-term consumption of foods containing citric acid may lead to hypocalcemia and increase the risk of duodenal cancer. Based on the impact of citric acid on calcium metabolism, people who often eat cans, drinks, jam and sour candy, especially children, should pay attention to calcium supplementation, Drink milk, fish head, fish bone soup, eat small shrimps and so on, so as not to cause calcium deficiency and affect health. Gastric ulcer, gastric acid, dental caries and diabetes patients should not often eat citric acid. Citric acid cannot be added to pure milk, otherwise it will cause pure milk to solidify. The dairy industry often mixes citric acid into a solution of about 10% and adds it to the low concentration milk solution. When adding, it should be stirred quickly.

Food industry:

Citric acid is the largest organic acid produced by biochemical methods in the world. Citric acid and salts are one of the pillar products of the fermentation industry. They are mainly used in the food industry, such as sour agent, solubilizer, buffer, antioxidant, deodorizer, flavor enhancer, gelling agent, toner, etc.
In terms of food additives, they are mainly used in cool drinks and pickled products such as carbonated drinks, fruit juice drinks and lactic acid drinks. Their demand varies with the change of season and climate. Citric acid accounts for about 2 / 3 of the total consumption of sour agent. Adding citric acid to canned fruit can maintain or improve the flavor of fruit, improve the acidity of some fruit cans with low acidity (reduce pH value), weaken the heat resistance and inhibit the growth of microorganisms, and prevent the bacterial expansion and damage of canned fruit with low acidity. Adding citric acid as a sour agent in candy is easy to coordinate with fruit flavor. In gel foods, if citric acid is used in sauce and jelly, the negative charge of pectin can be effectively reduced, so that the hydrogen bonds between the pectin molecules can be combined and gel. When processing canned vegetables, some vegetables show alkaline reaction. Using citric acid as pH regulator can not only taste, but also maintain their quality. Citric acid has the characteristics of chelation and pH adjustment, so that it can increase the performance of antioxidants, inhibit enzyme activity and prolong the storage life of food in the processing of quick-frozen food.

Metal cleaning

Citric acid is an organic acid produced by microbial fermentation. It is widely used in detergent production. Its own specificity and chelation play a positive role. Citric acid has good performance in the actual use process, mainly in terms of safety. The raw materials for preparing citric acid are all from grain, which is a safe food grade microorganism. The use of citric acid will not affect the environment, it is easy to degrade under the action of microorganisms and heat, and its own chelating ability is also relatively strong. Mainly in time, citrate has strong chelating ability to manganese ions and iron ions, and the use effect is also prominent. The corrosion inhibition of citric acid in detergent is also prominent. Acid pickling is an important link in chemical cleaning. Compared with inorganic acid, citric acid is relatively weak, so it has little corrosion to equipment. Citric acid cleaning has strong safety and reliability, and the waste liquid is easy to be treated, which will not cause harm to human body
Sterilization and coagulation process
The combination of citric acid and 80 ℃ temperature has a good effect on killing bacterial spores, and can effectively kill the contaminated bacterial spores in the pipeline of hemodialysis machine. Calcium must participate in the formation of prothrombin activator and subsequent coagulation. Citrate ion and calcium ion can form a soluble complex that is difficult to dissociate, which reduces the concentration of calcium ion in blood and hinders blood coagulation.

Animal breeding

Citric acid is formed by carboxylation of acetyl coenzyme A and oxaloacetic acid in the body’s tricarboxylic acid cycle, and participates in the metabolism of sugar, fat and protein in the body. Natural citric acid exists in plant (such as lemon, citrus, pineapple, etc.) fruits and animal bones, muscles and blood. Synthetic citric acid is prepared by fermentation of sugary substances such as granulated sugar, molasses, starch and grapes. Adding citric acid to compound feed can disinfect, prevent mildew and prevent Salmonella from infecting animal feed. Animal intake of citric acid can reduce the proliferation of pathogens, inhibit the production of toxic metabolites and improve animal stress