Casein modified

Figure 20. Sulfur 2p spectrum from casein modified with ethyl vinyl sulfone. (Reproduced, with permission, from Ref. 48. Copyright 1976, North-Holland...

Chobert, J.-M., Sitohy, M.Z., and Whitaker, J.R. 1988a. Solubility and emulsifying properties of caseins modified enzymatically by Staphylococcus aureus V8 protease. J. Agric. Food Chem. 36, 220-224. 

Medina, A.L., Colas, B., Le Meste, M., Renaudet, I., and Lorient, D. 1992. Physicochemical and dynamic properties of caseins modified by chemical phosphorylation. J. Food Sci. 57, 617-620. 

Some physical and functional properties of casein modified by the covalent attachment of amino acids are given in Table IX. Despite extensive modification, the relative viscosities of 2% solutions of the modified proteins did not change significantly, with the exception of aspartyl casein which was more viscous. There was some decrease in the solubilities of aspartyl casein and tryptophyl casein as compared with the casein control. It is anticipated that adding some 11.4 tryptophyl residues per mole of casein would decrease the aqueous solubility of the modified protein. However the results with aspartyl casein are unexpected. The changes in viscosity, solubility, and fluorescence indicate that aspartyl casein is likely to be a more extended molecule than the casein control. There was a marked decrease in the fluorescence of aspartyl casein and tryptophyl casein (see Table IX). The ratios of the fluorescences of acetylmethionyl casein to methionyl casein and t-BOC-tryptophyl casein to tryptophan casein were 1.20 and 2.01, respectively, indicating the major effects that these acyl groups have on the structure of the casein. 

Table IX. Some Physical Properties of Casein Modified by Covalent Attachment of Some Amino Acids0...

FIG. 7. Specificity of the cell envelope-associated proteinase from Lactococcus lactis ssp. lactis NCDO 763 (Monnet et al, 1992) on os2-casein. Modified from Fox et al (1995). 

Hydrophobic flavors, food oils, and fats are often encapsulated with a water-soluble shell material applied by spray drying from water (65), but gelatin-based shells formed by complex coacervation can also be used (66). Water-soluble shell materials applied by spray drying include milk protein (casein), modified starches, gum arabic, maltodextrins, or blends of these polysaccharide polsrmers with mal-todextrins. Vitamins are encapsulated with zero bloom strength gelatin by spray drying. 

Utsunomiya, N. Chuyen, N,V Kato, H. Nutritional and physiological effects of casein modified by glucose, diacetyl, or hexanal. J. Nutr. Sci. Vitaminol. 1990, 36, 387. 

Chuyen et al (1991) also studied the nutritional and physiological effect of casein modified by glucose under various conditions on growing of adult rats. They also had... 

The precipitation of casein in its uncombincd form by the addition to milk of one or another acid, forms the basis of all methods of preparation. These differ widely, however, in the subsequent purification. In the method of Hammarsten,4 just enough alkali is added to dissolve this casein completely. The alkalinity reached in this process somewhat modifies its physical properties but probably not its composition. In the method of Van Slyke and Bosworth 5 the last trace of calcium is removed by adding oxalate to an ammoniacal solution of the casein, but... 

Regenerated proteins from casein (lanital), peanuts (ardil), soybeans (aralac), and zine (vicara) are used as specialty fibers. Regenerated and modified cellulose products, including acetate, are still widely used today and the production of fibers is similar to that described above for synthetic fiber production. Most regenerated cellulose (rayon) is produced by the viscose process where an aqueous solution of the sodium salt of cellulose xanthate is precipitated in an acid bath. The relatively weak fibers produced by this wet spinning process are stretched to produce strong rayon. 

For the purpose of synthesizing flavor peptides or proteins in large scale, we developed "protein recombination method" and "enzymatic synthesis using chemically modified enzyme". "Protein recombination method" was applied to the synthesis of C-terminal portion of p-casein and its analog. Chymotrypsin was chemically modified by Z-DSP in aqueous solution. It was stable for organic solvents. Using this modified enzyme, we succeeded in the synfiiesis of Inverted-Aspartame-Type Sweetener "Ac-Phe-Lys-OH" in one step. 

Feathering Test. Modified soy proteins were investigated as a substitute for sodium caseinate in coffee whitener. A 15 mg/mL protein solution was heated at 70 C for one hour with intermittent stirring. To 10 mL of the solution, 1.5 g of Louana vegetable oil was added. The... 

It is pertinent to note here the observed increase in the value of the structure-sensitive parameter p from 1 to 2. This implies that the architecture of the sodium caseinate aggregates, as modified by interaction with the surfactant, becomes generally more open, despite the inferred collapse of their constituent protein nanoparticles. In contrast, a shell-like aggregation structure can be inferred for the self-assembly of sodium caseinate as a result of its interaction with the non-ionic surfactant PGE (this surfactant is based on a mixture of the esters of stearic and palmitic acids in chemical combination with polyglycerol (Krog, 1997)). 

We have seen earlier in this chapter how the self-assembly of casein systems is sensitively affected by temperature. Another thermodynamic variable that can affect protein-protein interactions in aqueous media is the hydrostatic pressure. Static high-pressure treatment causes the disintegration of casein micelles due to the dismption of internal hydro-phobic interactions and the dissociation of colloidal calcium phosphate. This phenomenon has been used to modify the gelation ability of casein without acidification as a consequence of exposure of hydrophobic parts of the casein molecules into the aqueous medium from the interior of the native casein micelles (Dickinson, 2006). High-pressure treatment leads to a reduction in the casein concentration required for gelation under neutral conditions, especially in the presence of cosolutes such as sucrose (Abbasi and Dickinson, 2001, 2002, 2004 Keenan et al., 2001). 

Other Protein Components. Other protein components In complex food systems and In protein Ingredient preparations may Interfere with or modify gelation reactions. Protein Interaction between whey protein and casein upon heating has a profound Influence on the characteristics of the casein gel structure In cheesemaking. Similarly protein Interactions are Important to meat structures. Protein-protein Interaction between soy and meat proteins has also been demonstrated with heat treatment (28). While concrete Interaction data have not been collected on protein gels formed from protein combinations, gelation properties of whey proteln/peanut flour blends have been Investigated GU) ... 

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