Sodium hydroxide casein

Sodium caseinate is produced by reacting the acid casein with sodium hydroxide. 

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... 

Whole milk (2 litres) is diluted with an equal volume of water at 30°-40° and commercial rennet (0-1 g.), dissolved in a few cubic centimetres of water, is added. The mixture is then left at the same temperature until separation of the casein is complete (about two hours). The whey is filtered through a filter cloth, and after the liquid has run off the residue is pressed down well. The casein, which contains a great deal of fat, is ground in a mortar with a little 1 per cent sodium hydroxide solution 1 to 1-5 litres of sodium hydroxide solution of the same concentration are then poured on to the resulting paste, and the mixture is gently warmed in a porcelain basin until all but the fat dissolves. 

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... 

In the latter part of the 1950s, this author (Hayes, 1960) attempted to repeat the experimentation used by Waksman and Iyer (1932,1933). He exhaustively washed powdered wheat straw with boiling water, then with hot dilute hydrochloric acid, and extracted twice for 5h in an autoclave at 120 °C, each time with a 4% sodium hydroxide solution. The combined filtrates were acidified to pH 4 with hydrochloric acid and the precipitate formed was washed free of chloride and freeze-dried. A ligno-casein complex was formed by reacting three parts of the lignin extract and one part casein in a 0.1 M solution of sodium hydroxide and collecting the precipitate formed when the pH was adjusted to 4. This complex was washed free of chloride and freeze-dried. A 6 1 lignin-protein complex was formed in the same way. 

Suspend a quantity of casein BRP equivalent to 155 gcf dried substance in 5 mL of water, add 10 mLof 0.1 N sodium hydroxide, and stir for 1 min (determine the water content of casein BRP prior to the test by heating at 60°C in vacuo for 4 hi. Add 60 mL of water and stir with a magnetic stirrer until the solution is practically dear. Adjust to pH 8.0 with Oil N sodium hydroxide or 0.1 N hydrochloric acid. Dilute to 100.0 - with water, Use the solution cm the day nfninmrAtimi. 

Vitamin-Free, Acid-Hydrolyzed Casein Solution Prepare the solution by mixing 400 g of vitamin-free casein with 2 L of boiling 5 N hydrochloric acid. Autoclave for 10 h at 121°. Concentrate the mixture by distillation under reduced pressure until a thick paste remains. Redissolve the paste in water, adjust the solution to pH 3.5 0.1 with a 10% solution of sodium hydroxide, and dilute with water to a final volume of 4 L. Add 80 g of activated charcoal, stir for 1 h, and filter. Repeat the treatment with activated charcoal. Filter the solution if a precipitate forms on storage. 

Casein Substrate Place 1.25 g of finely powdered casein in a 100-mL conical flask containing 5 mL of water, shake to form a suspension, add 10 mL of 0.1 A sodium hydroxide, shake for 1 min, add 50 mL of water, and shake for about 1 h to dissolve the casein. Adjust the pH to about 8.0 0.1, using 1A sodium hydroxide or 1A hydrochloric acid. Transfer the solution to a 100-mL volumetric flask, dilute with water to volume, and mix. Use this substrate on the day it is prepared. 

The casein content of the dry adhesive varies from 30% to 70% depending on its use. Extenders and fillers such as soy and wood flours are added to obtain an economical adhesive. One or more alkalis such as sodium hydroxide, lime,... 

Test the solubility of egg albumen, casein, and gelatin in water, in dilute sodium hydroxide solution, and in dilute hydrochloric acid. 

C) Color Reactions of Proteins. (1) Biuret Reaction. To 5 ml of the solution to be tested add 2 drops of very dilute (0.1 per cent) copper sulfate solution and shake well. Then add 2 ml of sodium hydroxide solution, mix, and allow to stand. A violet color is characteristic of the biuret reaction. Use the reaction for tests on the following solutions egg albumen, casein, glycine, oxamide, and biuret. 

D) Protein Plastics. To 0.1 g of casein in a test tube add 1 ml of 6 iV sodium hydroxide solution and 1 ml of water. Warm and shake until it dissolves. Pour one half of this solution on a watch glass, add 5 drops of formaldehyde, and stir with a rod. Examine both casein solutions after 5 minutes. 

Derivation By dissolving casein in sodium hydroxide and evaporating. 

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. 

The raw materials used for the preperation of regenerated protein fibres may be milk, soyabeans, peanuts and zein. Sometimes alkaline solutions of gelatin, albumin and other raw materials like waste wool, silk and feathers may be used. Fibrolane (Great Bretain) and Merineva (Italy) are made by dissolving casein in sodium hydroxide, and then by extrusion into an acid/saltbath. The fibres formed in this way... 

Hayashi and Kameda have reported 40% to 70% decreases in pepsin-catalyzed hydrolysis of lysozyme, soybean protein, casein and rlbonuclease A due to alkali-treatment under slightly milder conditions than ours (16, 29). Friedman, Zahnley and Masters reported an 80% decrease in digestibility of sodium hydroxide-treated casein measured as hydrolysis by trypsin (17). However, trypsin is specific for lysyl residues and lysine levels decreased to about half control values during the alkali-treatment, with a concomitant Increase in LAL formation. The somewhat lower digestibilities reported by these laboratories compared to our observations may be due to LAL formation in the proteins other than zein. 

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.)... 

Finally, to provide mold resistance adequate for interior and covered exterior structural requirements, a fungicide must be added to casein glues [40,58]. In this case there is no excess of sodium hydroxide in the glue composition to convert a water-insoluble fungicide to its soluble sodium salt. Therefore, it is added as a prepared soluble salt in order not to upset the fairly precise alkaline balance in the dry glue composition needed to fully disperse the casein. Sodium orthophenylphenate and sodium pentachlorophenate are examples. 

Caseins in pasteurised and steriHsed milk do not denature, but thermal processes lead, to a certain extent, to their dephosphorylation (phosphoserine hydrolysis), to proteolysis and aggregation of molecules. Casein could be completely dephosphorylated by incubation at 37 °C with 1% sodium hydroxide for a period of 24 hours. Under extreme conditions, such as during heating of sodium casemate (see the next section) at 120 °C for 1 hour, about 50% of phosphoproteins are dephosphorylated and after 5 hours of heating the dephosphorylation reaches 100% and the extent of the casemate hydrolysis is from 10 to 20%. 

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. 

Casein has been used as a central binder type in the past, but nowadays is of only marginal importance in cast coatings. For its appHcation it must be present in the dissolved state. It is dissolved by the addition of alkaH (e. g., ammonia, sodium hydroxide, borax, or sodium carbonate) either separately in a cooker (up to 70 °C) or with the pigment in a kneader. The casein concentration is limited to ca. 20% due to its high viscosity. The Hmit of processabiHty is shifted to ca. 33% by the addition of urea or dicyanodiamide, which reduces the viscosity and increases the storage stabihty of casein solutions. The mixing of casein solutions with pigments. 

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