What is the function of citric acid and sodium citrate buffer?

Citric acid is mainly used as acidulant, solubilizer, buffer, antioxidant, deodorant, odorant, gelling agent, toner and so on. In addition, citric acid has the functions of bacteriostasis, color protection, flavor improvement and sucrose conversion. Citric acid also has chelation, which can remove some harmful metals. Citric acid can prevent oxidation caused by enzyme catalysis and metal catalysis, thus preventing quick-frozen fruits from discoloring and changing taste.

Second, sodium citrate buffer solution

Ssc, namely sodium citrate buffer, is the most standard imprinting and molecular hybridization treatment solution in molecular biology. 20*SSC is used to denature and clean the concentrated buffer commonly used in hybridization experiments. Used for denaturation in hybridization experiments.

Extended data

Matters needing attention

Edible danger

Citric acid is an edible acid, which can enhance the normal metabolism in the body. Proper dosage is harmless to the human body. Adding citric acid to some foods tastes good and can stimulate appetite. In China, citric acid is allowed to be used in jam, beverage, canned food and candy. Although citric acid has no direct harm to 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.

Children are characterized by nervous system instability, excitability and autonomic nervous disorder; Adults have hand and foot convulsions, muscle spasms, paresthesia, itching and digestive tract symptoms.

Based on the influence of citric acid on calcium metabolism, people who often eat canned food, drinks, jam and sour sugar, especially children, should pay attention to calcium supplementation, drink more milk, fish head and fish bone soup, and eat some shrimps to avoid calcium deficiency and affect their health. Patients with gastric ulcer, hyperacidity, dental caries and diabetes should not eat citric acid often.

Citric acid cannot be added to pure milk, otherwise it will lead to the solidification of pure milk. In the dairy industry, citric acid is often mixed into 10% solution, which is added to low-concentration milk solution and stirred quickly.

Industrial danger

Health hazard: concentrated citric acid solution can stimulate mucosa. In industrial use, contact may cause eczema;

Danger of explosion: Citric acid is flammable. Powder and air can form an explosive mixture, which may cause combustion and explosion in case of open flame, high heat or contact with oxidant.

Storage conditions

Citric acid monohydrate loses its crystal water in dry air or when heated to about 40℃, and slightly deliquesces in humid air. Dilute citric acid aqueous solution can be allowed to stand and ferment. Therefore, solid monohydrate or anhydrate should be stored in a closed container and in a cool and dry place.

Baidu encyclopedia-citric acid

Baidu encyclopedia -ssc