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What is citric acid?

What is citric acid?

Citric acid is naturally found in citrus fruits, especially lemons and limes. This is what gives them a sour, sour taste.

This passage is going to talk about the followings of citric acid:

(1) Definition of fumaric acid

(2) How is citric acid made?

(3) Applications of citric acid


(1) Definition of fumaric acid

Citric acid is a weak organic acid with a molecular formula of C6H8O7. It is naturally found in citrus fruits. In biochemistry, it is an intermediate product of the citric acid cycle and occurs in the metabolism of all aerobic organisms.

Citric acid is a white powder used to make beverages and foods sour. Because it increases the acidity of the product, and many bacteria that cause food spoilage cannot grow in an acidic environment, it is also used as a preservative to prevent spoilage. It is also used in dietary supplements because when they are connected with citric acid, the body absorbs minerals better.


(2) How is citric acid made?

Citric acid is naturally present in citrus fruits, but the production of citric acid from citrus fruits is very expensive, and the demand for citric acid is greater than the available supply of citrus fruits. Therefore, when you see citric acid on the product label, you can be sure that it is a powder made by sugar fermentation.

A culture of Aspergillus Niger (a fungus commonly used in the pharmaceutical industry) adds sugar and metabolizes it into a liquid solution. Mix the solution with lime (calcium hydroxide), which causes citrate to fall out of the solution (precipitation). The citrate is then treated with sulfuric acid to make usable citric acid.

Citric acid is available in anhydrous form or monohydrate form. The anhydrous form crystallizes from hot water, while the monohydrate is formed when citric acid crystallizes from cold water. The monohydrate can be converted to anhydrous form at about 78°C. Citric acid can also be dissolved in anhydrous ethanol at 15°C (76 parts of citric acid per 100 parts of ethanol). Above about 175°C, the decomposition of carbon dioxide will decompose.

The sugar used for citric acid can come from sucrose, corn or wheat. In the United States, citric acid is most often derived from corn because it is a cheap, subsidized crop. In South America, sucrose is often used due to low sugar prices, while in Europe, wheat sweeteners are usually used.


(3) Applications of citric acid

The characteristics of citric acid make it an important additive in various industries. It is estimated that 70% of artificial citric acid is used in food and beverages, 20% in medicines and dietary supplements, and the remaining 10% is used in detergents.

In the food industry, artificial citric acid is one of the most common food additives in the world. It is used to increase acidity, enhance flavor and retain ingredients. Soda water, fruit juices, powdered beverages, candies, frozen foods and certain dairy products often contain artificial citric acid. It is also added to canned fruits and vegetables to prevent botulism. As a medicine and dietary supplement, it is added to medicines to help stabilize and retain active ingredients, and is used to enhance or mask the taste of chewing and syrup-based medicines. Mineral supplements (such as magnesium and calcium) may contain citric acid (in the form of citrate) and enhance absorption.

In addition, citric acid is a useful disinfectant against many bacteria and viruses. Test-tube studies have shown that it may be effective in treating or preventing human norovirus, which is the main cause of food-borne diseases. Citric acid is sold commercially as a general-purpose disinfectant and cleaner to remove soap scum, hard water stains, lime and rust. It is considered a safer alternative to conventional disinfectants and cleaning products such as quaternary ammonium salts and chlorine bleach.




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