Casein isolation from milk

Figure 4.17 Oligosaccharides attached to casein isolated from bovine milk (1-2) or colostrum...

Caseins are usually isolated from milk by methods involving urea or some similar denaturant in high concentration. The native conformation of these proline-rich proteins may therefore not be fully recovered within a reasonable time after removal of the urea. How-... 

Thoma, C., and Kulozik, U. (2004). Methods of Obtaining Isolated Casein-Macropeptide From Milk and Whey and Functional Properties. In Bull. 389, International Dairy Federation, Brussels, pp. lA-11. 

The separation of dairy proteins by CE has been generally carried out by CZE and has been exhaustively covered in several review papers, - - thus Table 30.8 only presents the key methodologies that offer the reader an overview of their most distinctive features. Basically, dairy protein analysis has been performed in whole milk for the simultaneous determination of caseins and whey proteins, or in fractions isolated from milk after casein precipitation. The first approach being used when the quantitative determination of the major proteins is required for the calculation of casein/whey protein ratios or for authentication purposes where an analysis of the whole protein profile is required. In both cases, accurate quantitative data must be derived. However, few studies have addressed the analysis of both groups of proteins in a single run by presenting quantitative data based on calibration curves constructed with analytical standards and good recovery of all proteins from milk samples. 

Natural adhesives derived from animals, caseins from protein isolated from milk, and starch, a carbohydrate extracted from vegetable plants, for example are used for bonding paper and card in the packaging industries. 

Human milk has a lower casein content than bovine milk and consists mainly of (3 and k varieties whose exact amino acid compositions are slightly different from those of the latter in Table 12.13. At least one phosphate group is present in all varieties of casein, which are therefore phosphoproteins. In these caseins the phosphate groups are attached to serine residues (12.18a). Phosphoserine (12.18b) can be isolated from milk. Phosphothreonine units (12.18c) may be present in the milk from some species. 

Protein isolates from milk, soybeans, peanuts, cottonseed, and corn have been extruded to form bristles and textile fibers. For a number of years, these manmade, wool-like fibers, principally derived from milk casein, were on the commercial market in the U.S. and Western Europe. Protein wastes, such as chicken feathers, have also been extruded to form fibers with textile properties. 

Casein glue is made from a protein isolated from milk. The extraction process creates an adhesive that is waterproof. Its first use was in bonding the seam of cigarette paper. It provides a fast setting bond that requires very little adhesive 1 g of adhesive can bond 2000 cigarettes. 

Chemical nature Isolation of casein from milk Production of casein plastics Properties of casein Applications Miscellaneous Protein Plastics Derivatives of Natural Rubber Gutta Percha and Related Materials Shellac... 

Milk from cows contains 3.2% protein, about 80% of which is casein. Casein is isolated by a precipitation process from milk, involving heating, rinsing to remove whey, and drying to a powder. The yield is about 3 kg/ 100 kg skim milk. Rennet casein is obtained when the casein is precipitated by chymosin enzyme, also known as rennet, and acid casein is produced when precipitation is accomplished by acidification. Acid casein is usually found in the form of sodium caseinate or calcium caseinate, which are water-soluble salts. Caseinates are made by reacting NaOH or CaOH with a slurry of casein curd or powder and then spray drying (Southward, 2010). 

Since the discovery of the enkephalins in 1975 [11] a large number of endogenous opioid peptides have been detected in mammals, and at present three distinct families of opioid peptides are known (for a review, See Ref. 12). These are the enkephalins, the endorphins (a-, (J-, and y-), and the dynorphins and neoendorphins. The recently discovered endomor-phins [13] also may represent endogenous opioid peptides. Peptides with opioid activity have also been isolated from tryptic digests of milk casein... 

Cyclo(Leu-Trp), a bitter compound isolated from the fermentation of milk casein by Bacillus subtilis, opened up the field to flavor and fragrance properties. It was further noted that dipeptides became more bitter when blockage of both the amino and carboxyl groups occurred or the dipeptide was converted into a DKP. This phenomenon opened the field of taste exhibition. ... 

Colloids (casein micelles) of two different particle sizes are isolated from skim milk by centrifugation under different conditions. The sedimentation and diffusion coefficients of the two preparations are as follows ... 

When milk at a pH of less than 6.5 is heated for 20 to 30 min at 100°C, it coagulates to form a gel. Casein micelles isolated from such milk have denatured whey protein attached to micelle surfaces (Creamer et al. 1978). Such micelle surfaces aggregates of whey pro-... 

In the first part of this experiment, you are going to isolate casein from milk which has a pH of about 7. Casein will be separated as an insoluble precipitate by acidification of the milk to its isoelectric point (pH = 4.6). The fat that precipitates along with casein can be removed by dissolving it in alcohol. 

To isolate the casein from milk under isoelectric conditions. 

These regenerated proteins are obtained from milk (casein), soya beans, corn, and peanuts. More or less complex chemical separation and purification processes are required to isolate them from the parent materials. They may be dissolved in aqueous solutions of caustic, and wet-spun to form fibers, which usually require further chemical... 

Material of as yet unproven peptide nature was isolated from instant coffee powders by an Australian group prompted by the identification of opioid-active peptides in casein and gluten hydrolysates, and morphine in milk.<136,137) A product that bound to rat brain homogenates was found with characteristics of opioid antagonists (its binding ED50 value was little changed in the presence of Na+) and with an activity at 1.2 mg/ml equivalent to that of naloxone at 3.4nM(137)... 

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