Uses of Caseins

As well as being central to cheesemaking, casein is used to fortify flour, bread and cereals. In addition to its functions in food products, casein has many other industrial applications. Casein is much used in tonics and dietary supplements (Section 12.13). Caseinates are surfactants and will act as emulsifiers, water and fat binders, adhesives, thickening and gelling agents (Section 12.4). Either additional phosphorylation or dephosphorylation of casein can be carried out with consequent modification of some of its properties. 

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Casein may be considered to be a conjugated protein, that is the protein is associated in nature with certain non-protein matter known as prosthetic groups. In the case of casein the prosthetic group is phosphoric acid. The protein molecule is also associated in some way with calcium. The presence of these inorganic materials has an important bearing on the processability and subsequent use of casein polymers. 

The use of casein plastics was severely curtailed with the development of synthetic polymers, particularly after the Second World War. In addition stricter regulations concerning health and safety at work will have caused attention to be drawn to the formolising process. In the experience of the author the environment surrounding the formolising baths is most unpleasant and this will have accelerated the demise of the casein manufacturing industry. 

Solubility. Solubility is an important functional property per se, i.e. in fluid products, and is essential for other functionalities since insoluble proteins can not perform useful functions in foods. The caseins are, by definition, insoluble at their isoelectric points, i.e. in the pH range c. 3.5-5.S the insolubility range becomes wider with increasing temperature. Insolubility in the region of the isoelectric point is clearly advantageous in the production of acid casein and is exploited in the production of two major families of dairy products, i.e. fermented milks and fresh cheeses. However, such insolubility precludes the use of casein in acid liquid foods, e.g. protein-enriched fruit juices or carbonated beverages. Acid-soluble casein can be prepared by limited proteolysis or by interaction with certain forms of pectin. 

In order to reach an analogous separation, Hammarsten proposes the use of casein to purify the lab extract of calf stomach lining Casein precipitates pepsin, while reimet remains in solution. The maceration of stomach lining is made in o 24 per cent HCl. The precipitation is caused by the addition of a 4 per cent solution of sodium caseate. To 130 c.c. of acid maceration are added, slowly and with shaking, 200 c.c. of a neutral solution of sodium caseate. Then N/10 NaOH is added until no further precipitation occurs. This precipitate contains the pepsin, while the rennet remains in solution. 

The use of casein and gelatin, also requiring great care, has not been adopted by any country. 

Casein (Section 12.17) is used in tonics, dietary supplements, infant foods, special diets and in post-operative feeding. Other medicinal uses of casein are in drug-carrying capsules and woundhealing preparations [33-37]. 

C.R. Southwood, Uses of casein and caseinates, Devel. Dairy Chem., 4, 173, 1989. 

About 50 years ago, the major uses of casein were in technogical appUcations, but nowadays casein products are regularly used as food additives, for example as ingredients that enhance some physical properties of foods, such as whipping, foaming, water binding, thickening and emulsification and nutritional properties. 

Humans have utilized the milk protein casein as a food source since the domestication of livestock. The use of casein in non-food applications dates... 

The use of casein and animal blood as adhesives goes back over many centuries, while the use of soybean flour and other soy products for adhesives and binders is a recent development in view of its long history as a food. Both casein and animal blood owe their place in adhesive history to the water-resistant formulations which have been made from them. 

Casein is utilized in diverse ways, as an adhesive, as a binder, and as a protective colloid and stabilizer for emulsified adhesive systems. Casein is sold as a raw material, and casein adhesives are sold in both the dry and liquid forms. The useful wood adhesive known as casein glue, which is formulated with lime and sodium salts, will be addressed later. This section will cover other uses of casein, for which the solubilization of the casein is generally accomplished with the use of heat, and at lower pH s than for the lime-containing glues. 

A comprehensive discussion of the use of casein and isolated soy protein in paper coatings may be found in Tappi Monograph Series No. 11 ... 

One of the better known uses of casein is the manufacture of foil-to-paper laminating adhesives. Because of its listing as GRAS by the FDA, casein is used for much of the packaging in the food and cigarette industries. 

The casein wood glues have a long history of use as interior structural adhesives, assembly adhesives, and panel-to-frame adhesives. A limited but important use is as a nonconductive adhesive in the construction of spacers for the large transformer boards for the electrical industry. The most popular use of casein and protein blend glues is in the production of hollow and solid core flush doors, an operation for which these glues are ideally suited. Most of the doors in this country are made with this type of glue. 

Some of the information on the use of casein as a protective colloid was obtained as a personal communication from colleagues, who requested no credit be given. 

In spite of this, the use of casein-based glues to bond aircraft structures continued until the middle of the Second World War their use in general plywood construction was phased out in the 1930s with the advent of P/F adhesives and, to a certain extent, by the U/F systems. 

The formolization reaction must be carried out slowly to avoid rapid hardening of the surface of the section which would reduce permeability and make it difficult to cure the centre of the material. The hardened material contains large quantities of water which must be removed slowly to prevent cracking and warping drying is thus carried out in humid air at about 45°C over a period of several days. The formolized material is then machined and polished to give the finished article. The use of casein for the preparation of... 

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