[Advances in Food Research] Advances in Food Research Volume 12 Volume 12 || Utilization of Synthetic Gums in the Food Industry

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<ul><li><p>UTILIZATION OF SYNTHETIC </p><p>GUMS IN THE FOOD INDUSTRY </p><p>BY MARTIN GLICKSMAN Techaical Cenler. General Foods Corporation. Tarrytown. N . Y </p><p>I . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 A . Economic Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 B . Cellulose Derivatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 C . Completely Synthetic Gums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 </p><p>11 . Microcrystalline Cellulose (Avicel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290 A . Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290 B . Food Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 </p><p>I11 . Sodium Carboxymethylcellulose (CMC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 A . Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 B . Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 C . Dairy Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 D . Bakery Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 E . Salad Dressings, Sauces, and Gravies . . . . . . . . . . . . . . . . . . . . . . . . . . . 305 F . Confectionery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307 G . Dietetic Foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308 H . Processed Foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310 I . Dry Package Mixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 J . Food Preservation Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312 I&lt; . Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313 </p><p>IV . Methylcellulose and Hydroxypropylmethylcellulose . . . . . . . . . . . . . . 314 A . Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314 B . Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 C . Bakery Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317 D . DieteticFoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 E . Dehydrated Foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322 F . FroeenFoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324 G . Edible Protective Coatings 327 H . Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327 </p><p>V Other Cellulose Derivatives 325 A Hydroxyethylcellulose (HEC) B . Ethylcellulose (EC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330 </p><p>D . Carboxymethylhydroxyethylcellulose (CMHEC) . . . . . . . . . . . . . . . . . . 331 E . Klucel-Mixed Cellulose Ether . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 </p><p>A . Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 </p><p>C . Food Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336 </p><p>. . . . . . . . . . . . . . . . . . . . . . . . . . . </p><p>. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . </p><p>C . Ethylhydroxyethylcellulose (EHEC) . . . . . . . . . . . . . . . . . . . . . . . . . 331 </p><p>VI . Polyvinylpyrrolidone (PVP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 </p><p>B . Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334 </p><p>283 </p></li><li><p>284 MARTIN GLICKSMAN </p><p>VII. Carbopol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340 A. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340 B. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 C. Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344 </p><p>VIII. Gantrez An . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 A. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 B. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347 C. Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348 </p><p>IX. Polyox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349 A. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349 B. Preparation , . , , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350 C. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351 D. Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353 </p><p>X. Research Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359 </p><p>1. INTRODUCTION </p><p>A. ECONOMIC BACKGROUND </p><p>Gums or hydrophilic colloids have been used in foods and in the food industry for hundreds of years to impart various functional properties to food products and thereby enhance over-all palatability and acceptability. The term gum has often been used incorrectly and ambiguously and has been applied to various rubbers, resins, etc., in the paint, rubber, and oil industries. I n the food industry, the term gum is more specifically de- fined as any material that can be dissolved or dispersed in a water medium to give viscous or mucilaginous solutions or dispersions. </p><p>In the past, most gums were natural materials derived from seaweed extracts, tree and bush exudates, plant seed flours, and similar sources, and were almost all polysaccharides or mixtures of polysaccharides. To- day a new and growing category of gums, which is still in its infancy, is that of the synthetic gums. Although synthetic gums are currently only a small fraction of the total gum market, comprising about 100,000,000 pounds of the total 3,000,000,000 pounds of water-soluble gums sold domestically (Anonymous, 1961a), they are steadily pressing a t the posi- tion of the natural gums and enlarging their foothold in the field as newer and better gums become available. </p><p>Proponents of synthetic gums point to the giant advances of organic chemistry and feel that, as silk was replaced by nylon, rubber by neoprenc, waxes by plastics, so the natural gum polymers are targets for the synthetic organic chemist. Although exact duplications may not be possible, or even desirable, sufficient of the functional properties can be reproduced syn- thetically to create marketing opportunities for these new materials. </p><p>As starting materials, the synthetic chemist has available two of </p></li><li><p>UTILIZATION OF SYNTHETIC GUMS IN THE FOOD INDUSTRY 285 </p><p>natures cheapest and most abundant raw materials-starch, a t about $0.06-0.09 per pound, and alpha-cellulose pulp, a t about $0.09-0.14 per pound. Both of these readily available polysaccharides are excellent start- ing materials for the production of gums. They both undergo chemical modification easiIy by heat, oxidation, or chemical treatment, and proper control of the modification makes possible a great variety of products. As Whistler (1959) pointed out, i t is conceivable that as more is learned about the relationship of structure to the physical properties of polymers, gum properties will probably be custom-tailored into starch and cellulose molecules so that they will more closely match the properties desired in special gum applications. Caution is urged, however, and i t must be re- membered that although synthetic chemical procedures may modify a polysaccharide to the desired end product, the materials and processing costs may be so high that the new gums will not be competitive in price with the natural gums. This is a stimulating challenge for industrial chemists and is a substantial protective barrier for the lower-cost natural gums. It is probable that in the foreseeable future, chemically modified starches and celluloses, as well as the purely synthetic gums, will con- tinually compete with the natural gums for the expanding markets for these materials. </p><p>As mentioned before, the traditional market for water-soluble gums was estimated to have been 3 billion pounds in 1961 (Anonymous, 1961a). Of this total, the largest percentage by far was held by the natural gums, including the starches, whereas only about 100 million pounds was com- posed of the synthetic gums. A conservative projection of the expanding markets for this material suggests that by 1970 the total market will have expanded to 4 billion pounds, with the proportion held by synthetics doubling to 200 million pounds. The author feels that this estimate is much too conservative, and that the market for synthetic gums will increase a t a much faster rate. This seems to be evident from more recent data compiled by Berger (1962), in Table I, which estimate the total con- sumption of synthetic gums in 1962 a t 127,000,000 pounds, and this com- pilation is incomplete, not including data on such synthetics as Gantrez An, Polyox, Carbopol, and other newer and less known gums. In addition, estimates of the potential market for water-soluble films alone range up to 20,000,000 lb per year (Anonymous, 1961a). </p><p>In the food industry, the synthetic gums at present occupy a minor role. Of the total market of 100,000,000 pounds in 1961, only an esti- mated 12,000,000 pounds was consumed by the food industry (Anonymous, 1961a), and this was chiefly by well-established gums such as carboxy- methylcellulose and methylcellulose. The newer synthetics will have a difficult, up-hill, and expensive battle to develop markets in the food </p></li><li><p>286 MARTIN GLICKSMAN </p><p>TABLE I ESTIMATED CONSUMPTION OF WATER-SOLUBLE GUMS" </p><p>Millions of pounds </p><p>Cellulose derivatives Carboxymethylcellulose </p><p>Carboxymethylhydroxyethylcellulose </p><p>Ethylcellulose (not water-soluble) Hy droxy ethylcellulose </p><p>Ethylhydroxyethy lcell~ilose Methylcelluloc e </p><p>Polyacrylic acid salts Pol yacrylamide </p><p>Polyvinyl alcohol Polyvin ylpyrollidone </p><p>i Acrylates </p><p>Miscellaneous </p><p>Total </p><p>1957 1962 </p><p>32.7 48.0 </p><p>27.0 35.5 </p><p>1.8 2.5 2.5 4.5 </p><p>20.0 25.0 1 .o 11.5 </p><p>85.0 127.0 </p><p>a Berger, 1062. </p><p>industry. The reason, of course, is the stringent FDA regulations requiring extensive animal feeding tests and experimental assurance of nontoxicity before allowing their use as food additives. As a result, most companies developing water-soluble gums tend to loolc for industrial applications and strive to develop profitable markets in these nonfood industries before attempting to penetrate the food industry. The ease of penetration or ac- ceptance is, of course, dictated by the novel and unique functional proper- ties offered by the new gum that cannot be matched by the current avail- able ones, or by the simple advantage of a cost reduction or product qual- ity improvement. </p><p>In general, the synthetic gums tend to offer some of the following advantages over the natural gums: </p><p>1) Uniformity of properties 2) Constancy of price 3) Unlimited availability-not affected by crop failures, labor short- </p><p>4) LowB.0.D. I n a previous article, the author (Glicksman, 1962a) reviewed the </p><p>properties and applications of the natural polysaccharide gums in the food industry and covered the common seaweed extracts, tree exudates, and plant seed gums. This chapter is a similar review of the use of the synthetic </p><p>ages, etc. </p></li><li><p>UTILIZATION OF SYNTHETIC GUMS IN THE FOOD INDUSTRY 287 </p><p>gums in foods. It not only includes the well-established cellulose deriva- tives and modifications but also investigates the potential utility of newly available nontoxic gums that the author feels will eventually find a place on the shelf of the food manufacturer. </p><p>B. CELLULOSE DERIVATIVES The most abundant natural material in the world is cellulose, a linear </p><p>polymer of P-D-glucopyranose. It constitutes approximately one-third of all vegetable matter, where i t is the main constituent of the cell walls and provides the primary structural support for the plant. Cellulose has probably the largest molecular weight of all the natural polysaccharides and is one of the most resistant to attack by chemicals and microorgan- isms. I ts molecules tend to remain extended but may normally undergo a degree of turning and twisting. Because of its size and strong associative forces, i t can be brought into solution only under certain conditions. </p><p>The purest natural cellulose is cotton fibers or linters, which on a dry basis consist of about 98% cellulose. Wood contains about 40-500/0 and, together with cotton linters, is the most important commercial source for raw-material cellulose. Agricultural residues, such as corn stalks, corn cobs, and wheat straw, contain about 30% cellulose and are available as a vast reservoir of potentially available raw material (Whistler and Smart, 1953). </p><p>The cellulose derivatives commonly encountered in industry are ethers in which alkyl or hydroxyalkyl groups have been substituted upon one or more of the three available hydroxy groups in each anhydroglucose unit of the cellulose chain. </p><p>The effect of the substituent groups is to disorder and spread apart the cellulose chains so that water or other solvents may enter to solvate the chain. By controlling the type and amount (degree) of substitution, it is possible to produce products that have a wide range of functional properties (Battista, 1958). </p><p>A typical substituted structure would be represented as follows : ~ o ~ l p - o + i I H OR ! </p><p>I I I H -O I I </p><p>L </p><p>where R = a substituent group. </p></li><li><p>288 MARTIN GLICKSMAN </p><p>The more important water-soluble derivatives are the following, where R is: </p><p>HO-CHZ-CHZ- H y droxyethyl- NaO 0 C-CH 2...</p></li></ul>

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