# Carboxymethylcellulose

The backbone of carboxymethylcellulose is anionic and amphiphilic, two characteristics that explicitly aid in stabilization.

## Volume 2

Vassilis Kontogiorgos, in Encyclopedia of Dairy Sciences (Third Edition), 2022

### Carboxymethylcellulose (CMC)

CMC is a cellulose derivative and is composed of derivatized glucose joined via β-(1, 4) glycosidic linkages. CMC is formed after cellulose dispersion in alkali followed by treatment with monochloroacetic acid to substitute hydroxyl groups of glucose at positions O-2, O-3, or O-6. The degree of substitution ranges between 0.5 and 1 for CMC that is made for food applications. Degree of substitution and molecular weight (i.e., degree of polymerization) usually determine CMC functionality. As CMC 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. CMC can be used to control ice crystal growth in ice cream (Regand and Goff, 2003) or as a rheology modifier in yoghurt formulations (Arancibia et al., 2011).

URL: https://www.sciencedirect.com/science/article/pii/B9780128187661003214

## Cellulose

R. Ergun, ... B. Huebner-Keese, in Encyclopedia of Food and Health, 2016

### Carboxymethylcellulose

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 CMC would increase with decreased DP and increased carboxymethyl substitution and substitution uniformity. The viscosity of the solution increases with increasing DP and increasing concentration.

CMC 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. It is also used in acidified protein drinks to stabilize protein and prevent it from precipitating. CMC is also added to syrup and sauce formulations to increase viscosity. Bakery is another application where CMC is commonly used to improve the quality and the consistency of the end product. In tortilla breads, for example, it is used to improve the process ability of the dough and the textural properties of the end product, including foldability and rollability.

URL: https://www.sciencedirect.com/science/article/pii/B9780123849472001276

## Natural Polymers

Aja Aravamudhan, ... Sangamesh G. Kumbar, in Natural and Synthetic Biomedical Polymers, 2014

### 4.6.2.2.2Cellulose Ethers

Carboxymethyl cellulose (CMC) is the major cellulose ether. By activating the noncrystalline regions of cellulose, selective regions of alkylating reagents can attack the cellulose. This is termed the concept of reactive structure fractions and is used widely for the production of CMC. Another route for carrying out the same reaction is by derivatization of cellulose in reactive microstructures, formed by induced phase separation. This process involves the usage of NaOH in anhydrous state in combination with solvents like DMA/LiCl. These CMC products have a distribution of substituents that deviate significantly from statistical prediction of the product theoretically.

CMC is used in several drug delivery and tissue engineering purposes. The release of apomorphine, a drug used to regulate motor responses in Parkinson’s disease, was successfully incorporated into CMC powder formulation and exhibited a sustained nasal release, and performed better than starch-based delivery vehicle [179]. Sodium CMC has been used successfully in gastrointestinal drug delivery [180]. Hence, CMC is seen as a successful drug delivery system for mucosal tissue [181]. Apart from drug delivery, CMC is useful as a scaffold in tissue engineering. CMC hydrogels having pH-dependent swelling characteristics were capable of releasing entrapped drug at the right pH present in the tissue of interest and showed great potential as a wound dressing material [182]. CMC hydrogels could be used for encapsulating cells of nucleus pulposis and hence are a potential replacement for intervertebral disk degeneration [183]. CMC has been combined with chitosan [184] and hydroxyapatite [185] for bone and dental regeneration purposes too.

URL: https://www.sciencedirect.com/science/article/pii/B9780123969835000041

## Cellulosics

Roland Adden, ... Matthias Knarr, in Handbook of Hydrocolloids (Third Edition), 2021

### 15.4.4.2Water binding for a broad range of applications

CMC is a very efficient thickener that hydrates in cold and warm water. The binding ability exceeds 100 g water per gram CMC and provides stable water retention during long storage times. The solutions are colorless with a neutral flavor. A large range of viscosities are available for a broad range of applications. In a 2% aqueous solution, the viscosity can approximately be between 30 and 60,000 mPa s, depending mainly on the degree of polymerization (DP). With increasing CMC concentration, the viscosity is increasing nonlinearly. As a rule of thumb, doubling the CMC concentration will increase the viscosity of the CMC by a factor of 6–10. With increasing temperature, the viscosity of the CMC solution decreases reversibly. Shear force is causing a reversible thinning effect. The thixotropic CMC solution builds back viscosity after shear is removed. Viscosity is also reduced by increasing salt concentrations as well as decreasing the pH. The maximum viscosity is present around a pH of 6.5–8.5.

The thickening effect of CMC can be used in soups, sauces, and ketchup. The fast hydration and water retention ability as well as the shear thinning effect during piping or filling are supporting properties for these applications. On top, CMC improves the mouthfeel and creamy texture, and reduces phase separation and syneresis. The water binding effect is also utilized in processed meat applications. Besides these savory applications, sweet products like waffle fillings with a high sugar content can be stabilized and thickened as well.

URL: https://www.sciencedirect.com/science/article/pii/B9780128201046000115

## Cellulases

James E. McDonald, ... Alan J. McCarthy, in Methods in Enzymology, 2012

### 2.6Carboxymethyl cellulose (CMC)

CMC is a derivative of cellulose, containing carboxymethyl groups that are generated via the reaction of cellulose with chloroacetate in alkali to produce substitutions in the C2, C3, or C6 positions of glucose units (Gelman, 1982). As a result, CMC is water soluble and more amenable to the hydrolytic activity of cellulases. CMC is therefore a useful additive to both liquid and solid medium for the detection of cellulase activity, and its hydrolysis can be subsequently determined by the use of the dye Congo red, which binds to intact β-d-glucans. Zones of clearing around colonies growing on solid medium containing CMC, subsequently stained with Congo red, provides a useful assay for detecting hydrolysis of CMC and therefore, β-d-glucanase activity (Teather and Wood, 1982). The inoculation of isolates onto membrane filters placed on the surface of CMC agar plates is a useful modification of this technique, as the filter may subsequently be removed allowing visualization of clear zones in the agar underneath cellulolytic colonies.

URL: https://www.sciencedirect.com/science/article/pii/B9780124159310000197

## Polysaccharide Ingredients

Kevin Philp, in Reference Module in Food Science, 2018

### Properties and Application: CMC

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. The CMC also slows the settling of any fruit pulp (Fig. 5) and, even when settled, prevents the pulp from forming a hard, difficult to disperse layer.

URL: https://www.sciencedirect.com/science/article/pii/B9780081005965223676

## Cellulose and Cellulose-Based Hydrocolloids

James N. BeMiller, in Carbohydrate Chemistry for Food Scientists (Third Edition), 2019

### Carboxymethylcelluloses

Carboxymethylcellulose (CMC), the sodium salt of the carboxymethyl ether of cellulose,10 is widely used as a hydrocolloid. For production of CMC, alkali cellulose is reacted with the sodium salt of chloroacetic acid. (Alkali cellulose is shown below as being 100% ionized, but may not be. In the case of cellulose, a much stronger solution of sodium hydroxide is used, so there are undoubtedly more hydroxyl groups in the alkoxy (R–O‾) form than in the case of starch.

Most food-grade sodium CMC products have degree of substitution (DS) values in the 0.7–0.8 range, but some products may have a DS as low as 0.4. (For water solubility, CMC must have a DS of at least 0.4.) The usual CMCs of DS 0.7–0.8 hydrate rapidly because they are quite ionic. Therefore, to make a smooth solution (that is, one without lumps), one of the means of dispersing it described in Chapter 5 must be followed. As the DS of CMC increases, salt tolerance, hygroscopicity, and alcohol tolerance increase and its thixotropic nature (see below) decreases.

Substituent groups are found at O2, O3, and O6 of d-glucopyranosyl units in the approximate proportion of 2.1:1.0:1.6. The degree of uniformity of derivatization along the cellulose chain determines the behaviors of its solutions. Nonuniformly derivatized CMC is a good example of a hydrocolloid that produces solutions with thixotropic rheology. Nonuniform distribution leaves unsubstituted stretches of molecules available for junction zone formation with unsubstituted regions of other CMC molecules, producing thixotropy. As explained in Chapter 5, thixotropic fluids have the characteristics of a weak gel at rest. Why a CMC with nonuniform substitution behaves this way and undergoes shear thinning is diagrammed in Fig. 8.4. Nonuniformly derivatized CMC produces solutions with thixotropic rheology (that is, with hysteresis as apposed to instantaneous, reversible shear thinning [pseudoplasticity]) (Chapter 5) because (1) the molecules with shorter contacts (contacts held together by the fewest hydrogen bonds) disengage from junction zones first, while those with longer contacts require more energy and time for pulling away from associations of molecules, and (2) the relatively short “naked regions” require time to “find each other” and reestablish a junction after shear is removed. So there is a time dependency to both shear thinning and the subsequent rethickening when shear is removed. Uniform derivatization produces molecules with no long unsubstituted stretches. Because they do not contain “naked regions” that can bind to the “naked regions” of other CMC molecules, products with uniform substitution will form smooth, stable solutions. The “naked regions” of nonuniformly substituted CMC allow binding to powdered cellulose and MCC. Nonuniformly substituted CMC also interacts with certain hydrocolloids such as galactomannans (Chapter 9). Maximum viscosity is produced when CMC and guar gum are used together in a CMC to guar gum ratio of about 1:3.

CMC is available in a wide range of viscosity types, and as already discussed, solution viscosity depends mainly on the average MW of the water-soluble polysaccharide (Chapter 5). Solutions of higher MW (higher viscosity) products also exhibit greater pseudoplasticity or thixotropy. Because it is a highly ionic hydrocolloid, CMC's solubility and the viscosity of its solutions are affected by salts. As explained in Chapter 5 (Fig. 5.13), CMC should be dissolved in water before other solutes are added (not dispersed in a salt solution) to take full advantage of its properties. Effects of salts on solutions of CMC are a function of the type (DS and viscosity type) of the CMC, the type and concentration of the salt, and the pH. In general, monovalent cations form soluble CMC salts; divalent cations produce hazy dispersions; and salts of trivalent cations are insoluble (that is, aluminum ions will bring about precipitation, but aluminum ions are not encountered in foods).

Because CMC consists of long, fairly stiff molecules bearing negative charges, its molecules in solution are stretched out due to electrostatic repulsion of chain segments (that is, chain folding is restricted because any folding would bring the carboxylate groups closer together where their negative charges would repel each other). In addition, because the molecules repel each other, monodisperse,11 highly viscous, stable solutions result. Lowering the pH to less than 4 represses ionization of the carboxyl groups so that some lose their charge (-COO  -COOH). Molecular association then occurs and viscosity increases for a time, but viscosity cannot be maintained long term at pH values of less than 4 because of hydrolysis (depolymerization). At pH 3, insolubilization (precipitation) occurs due to extensive loss of the negative charge, changing the anionic polymer to a neutral polymer, which allows chain associations to occur. CMC undergoes hydrolysis with loss of viscosity when acidic solutions of it are retorted.

CMC 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. Its 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. It is the primary stabilizer in most ice cream products, where it is used to prevent growth of ice crystals (see Chapter 13). Keeping ice crystals small maintains the smooth, creamy consistency of the product. CMC also controls sugar crystal size in fondants.

CMC is used when proteins must be stabilized, such as in yogurt, fruit, soy, and other acidic drinks containing protein. CMC, 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 CMC, 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. It is both a binder and an extrusion aid in the preparation of pet foods and other extruded products. In baked goods, like cakes, CMC 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. Some of the many applications of CMC are given in Tables 8.2 and 8.4.

Table 8.4. Typical applications of carboxymethylcelluloses

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)

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 CMC 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.

URL: https://www.sciencedirect.com/science/article/pii/B978012812069900008X

## Biopolymers of sugarcane

Thalita Mendonça de Resende, Marcelo Moreira da Costa, in Sugarcane Biorefinery, Technology and Perspectives, 2020

### Carboxymethylcellulose

CMC is an ether prepared from the replacement of a hydroxyl group of glucose by a group of monochloroacetic acid, with the previous swelling of the cellulose with alkali. The reactions [Eq. (12.1)—alkaline swelling/mercerization and Eq. (12.2)—etherification] for this preparation are described below (Heydarzadeh et al., 2009)

(12.1)${\left[{\mathrm{C}}_{6}{\mathrm{H}}_{7}{\mathrm{O}}_{2}{\left(\mathrm{OH}\right)}_{3}\right]}_{n}+n\mathrm{NaOH}\to {\left[{\mathrm{C}}_{6}{\mathrm{H}}_{7}{\mathrm{O}}_{2}{\left(\mathrm{OH}\right)}_{2}\mathrm{ONa}\right]}_{n}+n{\mathrm{H}}_{2}\mathrm{O}$
(12.2)${\left[{\mathrm{C}}_{6}{\mathrm{H}}_{7}{\mathrm{O}}_{2}{\left(\mathrm{OH}\right)}_{2}\mathrm{ONa}\right]}_{n}+n{\mathrm{ClCH}}_{2}\mathrm{COONa}\to {\left[{\mathrm{C}}_{6}{\mathrm{H}}_{7}{\mathrm{O}}_{2}\left({\mathrm{OH}}_{2}\right){\mathrm{OCH}}_{2}\mathrm{COONa}\right]}_{n}+n\mathrm{NaCl}$

The sodium CMC is an anionic polyelectrolyte, soluble in water, whose properties allow applications such as thickening agent, emulsifier, adhesive binder, wetting, dispersant, etc. However, these properties, as well as its applications, depend greatly on the degree of substitution (DS–average number of carboxymethyl per unit of anhydrous glucose) of carboxyl groups along the chain. The applications of CMC are varied and among them stand the uses in the segments: pharmaceutical, food, cosmetic, and petroleum (Martinez, 1996).

URL: https://www.sciencedirect.com/science/article/pii/B9780128142363000123

## Neuropeptide Analogs, Conjugates, and Fragments

Klaus Rissler, Hinrich Cramer, in Methods in Neurosciences, 1993

### Separation Media

Carboxymethylcellulose (CM-52) is obtained from Whatman (Springfield, UK). Plates (0.25 mm) for thin-layer chromatography (TLC) and microfine silica (QUSO) used for adsorption of the radiopeptide are purchased from Eastman Kodak (Rochester, NY) and Roth (Karlsruhe, Germany) respectively. Solid-phase extraction (SPE) is carried out by use of 1-ml Sep-Pak A (μBondapak C18) cartridges (Millipore–Waters, Eschborn, Germany). Spherisorb ODS II columns (125 × 4.6 mm I.D., 5 μm particle size) for HPLC are obtained from Bischoff Analysentechnik (Leonberg, Germany).