Casein availability

WL is the acronym for Wallerstein Laboratories, which originally marketed the medium. WL, sometimes called WL-Nutritional (WLN), does not contain cycloheximide and so is used for determination of total viable yeast populations. This WL medium contain a pH indicator, brom-cresol green, which permits rapid screening of acid-producing colonies. In addition, this medium contains casitone, a specially prepared pancreatic digest of casein available from Difco. 

Products prepared from soy protein products and resembling chicken, ham, frankfurters, and bacon are available commercially. Soy protein isolates are used in place of milk proteins or sodium caseinate in products such as coffee creamers, whipped toppings, yogurt, and infant formulas (see Dairy substitutes). Soy protein products also are used in snacks and in baked foods. 

Formolised casein is a rigid hom-like material which may be made available in a wide variety of colours and patterns. By common consent it is recognised as having a pleasant feel and appearance and it is properties which are relevant to cuiTent commercial application. 

When dry, casein is a good electrical insulator but is seriously affected by humid conditions. For this reason it can no longer compete with the many alternative plastics materials now available for electrical applications. 

Casein is used for a number of miscellaneous purposes in which foimolisation is not required. These include adhesives, stabilisers for rubber latex, paper finishing agents and miscellaneous uses in the textile industry. Mention may also be made of casein fibres, available in Italy between the two world wars under the name of Lanital. 

Casein is the only protein that has achieved commercial significance as a plastics raw material. Many other proteins are readily available in many vegetable material residues which arise from such processes as the extraction of oils and starches from seeds. It would be advantageous to countries possessing such residues if plastics could be successfully exploited commercially. Although plastics materials have been produced they have failed to be of value since they are invariably dark in colour and still have the water susceptibility and long curing times, both of which are severe limitations of casein. 

Nitrogen sources include proteins, such as casein, zein, lactalbumin protein hydrolyzates such proteoses, peptones, peptides, and commercially available materials, such as N-Z Amine which is understood to be a casein hydrolyzate also corn steep liquor, soybean meal, gluten, cottonseed meal, fish meal, meat extracts, stick liquor, liver cake, yeast extracts and distillers solubles amino acids, urea, ammonium and nitrate salts. Such inorganic elements as sodium, potassium, calcium and magnesium and chlorides, sulfates, phosphates and combinations of these anions and cations in the form of mineral salts may be advantageously used in the fermentation. 

It is generally not recommended to mix medications directly into the EN formula because of concerns that physical incompatibilities between the medications and the formula might lead to tube occlusion. There is some evidence that polymeric formulas are more likely to demonstrate physical incompatibility with medications compared with monomeric formulas, although most of the work in this area has used casein or caseinate-based formulas, and other proteins may act differently.38 The limited data currently available would indicate that acidic syrups and elixirs may be the worst for causing physical incompatibility when admixed with EN formulas. It has been postulated that this incompatibility is due to changes in the protein structure after exposure to acid or alcohol.38... 

These conclusions were seriously questioned (21-24 and recent results indicate that the bioavailability of Ca2+ is the same from a casein diet as from a high-phytate soy concentrate (25). Oberleas contends that, in the presence of adequate amounts of Ca2+ and vitamin D, dietary phytate is not rachitogenic, even though it may bind substantial amounts of Ca2+ (J 5). This controversy, the relative paucity of available information, and the growing incidence of Ca2+ deficiency prompted us to investigate further the chemical interactions between Ca2+ and phytate and to assess its effect on the bioavailability of Ca2+ administered to mice by gavage. 

Till this time, polymer science was largely empirical, instinctive, and intuitive. Several polymers were commercially available prior to World War I celluloid, shellac, Galalith (casein), Bakelite, and cellulose acetate plastics hevea rubber, cotton, wool, and silk rayon fibers Glyptal polyester coatings bitumen or asphalt, and coumarone-indene and petroleum resins. However, as evidenced by the chronological data shown in Table 1.1, there was little... 

Nature itself gives us a spectacular example of a biopolymer-based delivery system in the form of the native casein micelle of mammalian milk (Lemay et al, 2007). This is primarily a colloidal delivery system for calcium, where the micronutrient is in the form of calcium phosphate, which does not give a bitter taste, and which provides good bioavailability owing to its colloidal size, amorphous state and quick dissolution in gastric conditions (pH 1-2). Nevertheless, the casein micelle structure is unique there are no other readily available natural delivery systems for most nutraceuticals. Therefore some new designs are clearly required (Velikov and Pelan, 2008 McClements et al, 2008, 2009). 

Milk protein products. As indicated in Table 1, the food industry is placing major emphasis on the production and utilization of milk protein products in a wide variety of formulated food products (20,21,22). Although nonfat dry milk (NFDM) and whey powder are major milk protein ingredients in formulated foods, casein and whey protein concentrates, which contain their proteins in a more highly concentrated and functional form, are essential for certain food product applications, such as those products that require the proteins as an emulsifier agent. Additional details on the processing methods and conditions used to produce the various milk protein products are available (23). 

Whey protein concentrates (WPC), which are relatively new forms of milk protein products available for emulsification uses, have also been studied (4,28,29). WPC products prepared by gel filtration, ultrafiltration, metaphosphate precipitation and carboxymethyl cellulose precipitation all exhibited inferior emulsification properties compared to caseinate, both in model systems and in a simulated whipped topping formulation (2. However, additional work is proceeding on this topic and it is expected that WPC will be found to be capable of providing reasonable functionality in the emulsification area, especially if proper processing conditions are followed to minimize protein denaturation during their production. Such adverse effects on the functionality of WPC are undoubtedly due to their Irreversible interaction during heating processes which impair their ability to dissociate and unfold at the emulsion interface in order to function as an emulsifier (22). 

In comparison with sucrose (the annual production of which is 93 x 106 tonnes) and glucose or glucose-fructose syrups, only relatively small quantities of lactose are produced. However, it attracts commercial interest because it has some interesting properties and is readily available from whey, a by-product in the production of cheese or casein. World production of cheese is c. 1.4 x 107 tonnes, the whey from which contains c. 6 x 106 tonnes of lactose c. 0.3 x 106 tonnes of lactose are contained in the whey produced during casein manufacture. According to Horton (1993),... 

With the recent commercial availability of ultrafiltration, it has become possible to increase the concentration of casein, thus levelling out seasonal variations in milk composition and consequently in gel characteristics and... 

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