Carboxymethyl cellulose (CMC) or cellulose gum is a cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone. 

It is often used as its sodium salt, sodium carboxymethyl cellulose.

Carboxymethylcellulose

Sodium Carboxymethyl cellulose is an anionic polyelectrolyte, soluble in water, whose properties allow applications such as thickening agent, emulsifier, adhesive binder, wetting, dispersant, etc

Other names

Synonyms: sodium carboxymethylcellulose, sodium carboxymethyl cellulose, carboxymethylcellulose, carboxymethyl cellulose, CMC, sodium CMC, or cellulose gum, Carboxymethylcellulose, carmellose, E466

Identifiers

CAS Number

9004-32-4

EC / List no.: 618-378-6

CAS no.: 9004-32-4

Carboxymethyl cellulose is widely used in food products to absorb and hold water, to control crystal growth, to thicken, as a binder, to increase shelf life, and to provide desired texture or body. 

As Carboxymethyl cellulose is anionic it can form complexes with milk proteins depending on the formulation. 

In addition, high salt concentration has negative influence on viscosity due to masking of electrostatic interactions between CMC chains. 

Carboxymethyl cellulose can be used to control ice crystal growth in ice cream (Regand and Goff, 2003) or as a rheology modifier in yoghurt formulations

Carboxymethyl cellulose's largest volume use is in the preparation of dry pet foods that form their own gravy when warm water is added. 

Its second largest use is in the preparation of ice cream, sherbets, and other frozen desserts. 

Carboxymethyl cellulose is the primary stabilizer in most ice cream products, where it is used to prevent growth of ice crystals. 

Keeping ice crystals small maintains the smooth, creamy consistency of the product. 

Carboxymethyl cellulose also controls sugar crystal size in fondants.

Carboxymethyl cellulose is used when proteins must be stabilized, such as in yogurt, fruit, soy, and other acidic drinks containing protein. 

Carboxymethyl cellulose, a polyvalent anion, can stabilize protein dispersions, especially near their isoelectric pH value where they are least soluble, because the protein molecules will have multiple positive charges and can bind to CMC molecules. 

Using Carboxymethyl cellulose, milk products can be stabilized against casein precipitation when milk is acidified because CMC forms stable soluble complexes with casein at pH values in the range 3–6 where casein is insoluble.

Because of its rapid hydration, it affects hydration of other dry mix components. 

Carboxymethyl cellulose is both a binder and an extrusion aid in the preparation of pet foods and other extruded products. 

In baked goods, like cakes, Carboxymethyl cellulose is added to adjust the consistency of the batter, to increase product volume, to improve the quality of the finished product, to provide moisture retention, and to prolong freshness

Carboxymethylcellulose (CMC) is an anionic, water-soluble cellulose derivative. 

Solubility of CMC depends on the DP as well as the degree of substitution and the uniformity of the substitution distribution. 

Water solubility of Carboxymethyl cellulose would increase with decreased DP and increased carboxymethyl substitution and substitution uniformity. 

The viscosity of the solution increases with increasing DP and increasing concentration.

Carboxymethyl cellulose is soluble in water at any temperature. 

Because of its highly hygroscopic nature, CMC hydrates rapidly. 

Rapid hydration may cause agglomeration and lump formation when the CMC powder is introduced into water. 

Lump creation can be eliminated by applying high agitation while the powder is added into the water or preblending the CMC powder with other dry ingredients such as sugar before adding into water.

Due to its high solubility and clarity of its solutions, CMC is commonly used in beverages and beverage dry mixes to provide rich mouthfeel. 

Carboxymethyl cellulose is also used in acidified protein drinks to stabilize protein and prevent it from precipitating. 

Carboxymethyl cellulose is also added to syrup and sauce formulations to increase viscosity. 

Bakery is another application where Carboxymethyl cellulose is commonly used to improve the quality and the consistency of the end product. 

In tortilla breads, for example, Carboxymethyl cellulose is used to improve the process ability of the dough and the textural properties of the end product, including foldability and rollability.

CMC - usually forms a clear, colourless and tasteless solution. It is cold water soluble and some grades have a tolerance to high concentrations of sugar. It is available in a wide range of viscosities and has good heat stability. CMC is a good film former.

Ice cream: CMC is a common stabilizer in ice cream. It is cold water soluble and this gives it an advantage in ice cream mixes that are not subject to high temperatures. Unlike locust bean gum CMC does not give the ice cream any added melt-down resistance. CMC is more commonly used in the USA than in Europe and this may be related to a higher proportion of the European market being novelty items that benefit from improved melt-down resistance.

Bakery: CMC is commonly used in cakes, muffins and tortillas to improve the texture of the product by increasing moisture retention.

Beverages: CMC is used as a stabilizer in fruit drinks and in drink concentrates. Fruit drinks typically consist of fruit juice that is diluted with water. To improve the taste and texture of the drink a citric acid/citrate buffer is usually added, some extra sugar and CMC can be added to improve the mouthfeel of the drink. Low calorie drinks that do not have the viscosity contribution from the added sugar will have a very thin and watery mouthfeel without the addition of a viscosity modifier. 

Product types

Functions

Beverage mixes

Alcohol tolerance

Cake, doughnut, and related mixes:

Batter thickener

Humectant (improves texture and extends shelf life)

Increases volume (film former)

Cheese spreads

Protective colloid

Dietetic foods

Thickener

Bodying agent

Dressings

Thickener

Dry pet food

Makes gravy when water is added

Dry-powder fruit drink mixes and salad dressings: 

Suspending aid

Rapid hydration: 

Extruded products

Lubricant

Binder

Film former

Processing aid

Fondants

Inhibits sugar crystal growth

Frozen and dried egg white

Protein stabilizer

Hot cocoa mixes

Thickener

Ice cream and other frozen dessert products

Inhibits ice crystal growth

Improves mouthfeel, body and texture

Stabilizes casein

Icings and frostings

Inhibits sugar crystal growth

Prevents moisture loss.

Meat emulsions

Texturizer

Binder

Milk products

Protein stabilizer

Pie fillings

Improves texture

Prevents syneresis

Puddings

Inhibits sugar crystal growth

Sauces

Suspending aid

Syrups

Transparent thickener for low-calorie pancake syrup

Toppings

Holds moisture

Prevents syneresis

There is no limit to the concentration of Carboxymethyl cellulose that may be used in food products, but it should be used with good manufacturing practices in mind. 

Ingredient labels on products containing CMC may read sodium carboxymethylcellulose, sodium carboxymethyl cellulose, carboxymethylcellulose, carboxymethyl cellulose, CMC, sodium CMC, or cellulose gum.

Preparation

Carboxymethyl cellulose is synthesized by the alkali-catalyzed reaction of cellulose with chloroacetic acid.

The polar (organic acid) carboxyl groups render the cellulose soluble and chemically reactive.

Following the initial reaction, the resultant mixture produces approximately 60% CMC and 40% salts (sodium chloride and sodium glycolate); this product is the so-called technical CMC, which is used in detergents.

An additional purification process is used to remove salts to produce pure CMC, which is used for alimentary and pharmaceutical applications.

An intermediate "semi-purified" grade is also produced, typically used in paper applications such as the restoration of archival documents.

The functional properties of CMC depend on the degree of substitution of the cellulose structure, as well as the chain length of the cellulose backbone structure and the degree of clustering of the carboxymethyl substituents.

Uses

Introduction

CMC is used as a viscosity modifier or thickener, and to stabilize emulsions in various products, both food and non-food. 

Carboxymethyl cellulose is used primarily because it has high viscosity, is nontoxic, and is generally considered to be hypoallergenic, as the major source fiber is either softwood pulp or cotton linter. 

Non-food products include products such as toothpaste, laxatives, diet pills, water-based paints, detergents, textile sizing, reusable heat packs, various paper products, and also in leather crafting to help burnish edges.

Substance names and other identifiers

Cellulose, carboxymethyl ether, sodium salt

IUPAC names

2,3,4,5,6-pentahydroxyhexanal acetic acid sodium hydride

acetic acid; 2,3,4,5,6-pentahydroxyhexanal; sodium

Carboximethilcelullose

Carboxymethyl cellulose

Carboxymethyl Cellulose Sodium

Carboxymethyl cellulose sodium salt

Carboxymethyl cellulose, sodium salt

Carboxymethylcellulose

carboxymethylcellulose

Carboxymethylcellulose sodium salt

Cellulose carboxymethyl ether sodium salt

Cellulose Gum

Cellulose, carboxymethyl ether, sodium salt

Na carboxymethyl cellulose

sodium carboxy methyl cellulose

sodium carboxyl methyl cellulose

SODIUM CARBOXYMETHYL CELLULOSE

Sodium Carboxymethylcellulose

Sodium carboxymethylcellulose

sodium cellulose carboxymethyl ether

Trade names

Carboximetilcelulosa

Other names

Carboxy methyl cellulose sodium

Carboxymethyl cellulose

carboxymethyl cellulose sodium salt

carboxymethyl cellulose sodium salts

Carboxymethyl ether cellulose sodium salt

Carboxymethylcellulose Sodium Salt

Carboxymethylcellulose, sodium salt

cellulose carboxymethyl ether sodium salt

Cellulose, Carboxymethyl ether, Sodiu

SODIUM CARBOXYMETHYL CELLULOSE

Sodium carboxymethyl cellulose

Sodium Carboxymethylcellulose