Calcium hydroxide casein

Casein is used to fortify flour, bread, and cereals. Casein also is used for glues and microbiological media. Calcium caseinate is made from a pressed casein, by rinsing, treating with calcium hydroxide [1305-62-0], heating, and mixing foUowed by spray drying. A product of 2—4% moisture is obtained. 

CCP in milk is mentioned in connection with casein above (Section VI.C). Fluorapatite is a major constituent of phosphate rocks, and a constituent, probably important, of human tooth enamel for those whose drinking water contains significant amounts of naturally occurring or added fluoride. Fluorapatite is significantly less soluble than hydroxyapatite - the relationship between the solubilities of fluorapatite and hydroxyapatite parallels (but is much less extreme than) that between calcium fluoride (Ksp — 3.9 x 10 11 mol3 dm-9) and calcium hydroxide (Ksp = 7.9 x 10 6 mol3 dm 9). Calcium diphosphate, Ca2P207, is believed to be the least soluble of the calcium phosphates. 

Casein and caseinates are generally made from skim milk by adding hydrochloric or sulfuric acid or by lactic acid fermentation. The isoelec-trically precipitated casein is washed and dried or neutralized with sodium hydroxide, potassium hydroxide, or calcium hydroxide to produce the corresponding caseinate and spray dried. Rennet casein is... 

As with blood and soybean flour, the maximum adhesive capability of casein is attained only by complete aqueous dispersion of the folded protein molecules with a strongly alkaline inorganic salt such as sodium hydroxide [56]. Since sodium hydroxide cannot be incorporated successfully into a dry adhesive composition, it is quickly produced on mixing through a double decomposition reaction between calcium hydroxide and strongly ionized but less alkaline salts such as sodium fluoride, sodium carbonate, and trisodium phosphate. (The residues from this reaction are insoluble calcium compounds.)... 

Solidification of adhesives within a joint can be engineered by a reaction contrived within the joint at an appropriate speed. An example is the coagulation of milk protein (casein), which is mainly soluble in water but which coagulates in the presence of lime (calcium hydroxide). The protein solidifies through the action of alkalinity and remains so because the doubly charged calcium ions form bridges (crosslinks) between the protein molecules. Such adhesives are stable for millennia. 

Pure casein solutions do not curdle on boiling. Acids do not cause complete precipitation unless the temperature is raised to the boiling point. A slight excess of calcium hydroxide also causes turbidity and coagulation on warming. The turbid accumulation dissolves again when the temperature is lowered. Concentrated solutions of calcium and casein become covered with a film on boiling just as milk does. 

To produce caseinates, enough alkali, commonly called calcium hydroxide or sodium hydroxide, is added to acid coagulated casein to reach a pH of 6.7. The resulting suspension is pasteurized and spray dried. 

Brine, containing chlorine Cadmium chloride Cadmium cyanide Cadmium sulfate Calcium acetate Calcium bromide Calcium carbonate Calcium chlorate Calcium chloride Calcium fluoride Calcium hydroxide Calcium nitrate Calcium sulfate (gypsum) Calcium sulfide Calcium sulfite Calcium wolframate Carbon dioxide Casein... 

Soybean flour can be used as the main component in adhesive formulations, but it is commonly added as extender for phenolic systems, or blended with casein or other adhesives. They are packaged as dry powders that contain both proteins and carbohydrates. The flour is dispersed in aqueous sodium hydroxide for preparing the adhesive, and also calcium hydroxide is added to extend the open time and to improve water resistance. Soybean glues have a limited water resistance, but recover their strength on drying. They are also susceptible to mold growth, and some fungicides need to be included in the commercial formulations. Fillers are used to reduce cost, but they also lower the performance of the adhesive. Some commonly used fillers are wood and walnut-shell flours, and also clay. 

The casein, which is contaminated with calcium phosphate and fats, is filtered off to as small a volume as possible (about 500 cc.) and transferred to a 2-1. beaker. It is then treated with 0.1 M sodium hydroxide, the alkali being added slowly and with stirring through a capillary extending to the bottom of the beaker (Note 4). The addition of alkali is continued until the / ll of the mixture reaches 6.3 (Note 5) 100-150 cc. of the alkali is required. The end-poinl is determined by matching against... 

Put into a mortar 10 cc. of water and 3 or 4 drops of a dilute solution of sodium hydroxide. Test the solution with red litmus paper. Next add some casein and grind it thoroughly in the alkaline solution. Test the solution again with red litmus paper. What conclusion can you draw in regard to the chemical nature of casein. Filter the solution through a wet filter-paper, and add to the filtrate a few drops of a solution of calcium chloride. Explain. 

Casein is soluble in alkali hydroxides and in this way the soluble Na, K and NH4 salts are obtained commercially. Calcium caseinate will form stable colloidal dispersions while sodium and potassium caseinates dissolve to form viscous solutions and eventually aqueous gels above about 17% concentrations. The alkali metal salts are very stable to heat over a wide range of conditions. They can be heated to 140°C for several hours at pH 7, without decomposition. 

Casein is the main milk protein precipitated from skimmed milk as curds or cheese by acidifying. This casein is a mixture of many proteins, with molecular weights around 20,000-25,000. Although casein is insoluble at 3.5 < pH <5, it will dissolve in neutral and alkaline solutions. These solutions are fairly heat stable but very viscous above concentrations of 15%. Casein films deposited from dilute sodium and potassium hydroxide solutions will redissolve on warming, though ammonia solutions dry to insoluble films. Calcium and similar... 

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