Carboxymethylcellulose, or sodium carboxymethylcellulose is a food additive that has the properties of thickening, emulsifying, shaping, and preserving the freshness of products, and can be used instead of food additives, such as gelatin, agar and sodium alginate. For the first time carboxymethylcellulose was obtained in 1918, commercially produced from 1920. In modern conditions it is synthesized by chemical reactions from non-food natural raw materials.
In its dry form, carboxymethylcellulose is a white or slightly yellowish, amber or grayish powder, odorless and tasteless. Carboxymethylcellulose is readily soluble in water, but insoluble in most organic solvents, such as ethanol, methanol, or acetone. It can be dissolved in mixtures, if the content of organic solvent is less than 40%.
Carboxymethylcellulose is hygroscopic, that is, it has the ability to retain moisture, also has excellent water-binding capacity. The amount of water absorbed depends on the viscosity and type of substitution in the reaction, as well as on temperature. The lower the degree of substitution and the higher the viscosity, the higher the water absorption capacity of the substance. Hygroscopic properties are partly responsible for the success of CMC as a food and drug additive.
Synthesis of carboxymethylcellulose
Carboxymethylcellulose is synthesized by alkali-catalyzed reaction of cellulose with chloroacetic acid. During this reaction, the polar (organic acids) carboxyl groups make cellulose soluble and chemically reactive. The functional properties of CMC depend on the degree of substitution of the cellulose structure (the number of hydroxyl groups involved in the substitution reaction), as well as the length of the structure of the cellulose chain and the degree of clusterization of carboxymethyl substituents.
After the initial reaction, the resulting mixture gives approximately 60% carboxymethyl cellulose plus 40% salts (sodium chloride and sodium glycolate). This product is a so-called technical CMC, which is used in detergents. Another cleaning method is used to remove these salts to obtain pure carboxymethylcellulose, which is used in food, pharmaceuticals and toothpaste.
Use as a food additive
Carboxymethylcellulose is found in:
- chocolate milk;
- dry and condensed milk;
- sausage casings;
- seasonings and spices;
- soups and broths;
- beer, cider.
Carboxymethylcellulose sodium salt is often added to food as a stabilizer, as a recognized safe ingredient. Used for making ice cream, due to the ability to hold the mixture in a certain form. It is also added as a filler, emulsifier, firming and gelling agent, moisturizer and thickener.
Use as a thickener
Carboxymethylcellulose is added to some products as a thickener and dispersant. As a thickener, it facilitates uniform dispersion of ingredients throughout the mixture. It helps to keep solids suspended in liquids and acts as an emulsifier, while keeping lotions and creams in the right consistency.
It is also part of many non-food items, such as laxatives, diet pills, water-based paints, detergents, and various paper products.
Adding sodium carboxymethylcellulose to a liquid changes its viscosity. This property is achieved by the fact that carboxymethylcellulose molecules bind to each other, water compresses and breaks bonds. Viscosity, or resistance to liquid spilling, depends on the amount of sodium carboxymethyl cellulose added. Carboxymethylcellulose can be used to make thick, slowly pouring gels, eye drops with the effect of artificial tears, also in the oil industry as an ingredient of drilling mud, where it acts as a viscosity modifier and a water retaining agent.
Carboxymethylcellulose is usually considered a fairly safe dietary supplement. An allergic reaction is known to have this food supplement, which was observed in one woman in the form of anaphylactic shock, but this is an exception. It has no nutritional value or benefit for the body, because it is not absorbed in the digestive system, it is a ballast substance, but it can be a very useful food additive for all types of products.
Adding sodium carboxymethylcellulose to food can reduce the cost of food production, improve the taste of a food product and increase its shelf life, so it is an ideal additive in the food industry that can be widely used in the production of various types of solid and liquid beverages, canned food, candy, cakes , instant noodles, convenience foods, soy milk and fruit juice. Therefore, there is no reason to avoid carboxymethylcellulose, or to limit its consumption.