Casein antioxidant activity

The electronic property of the amino acid on the C-terminus also has an effect on antioxidant activity (Li et al., 2011), that is, the larger the electronic property, the higher is the activity. The C-terminus is a polar position that is thus affected by its electrostatic potential, to some extent therefore, the amino acids Trp, Glu, Leu, lie, Met, Val, Tyr, etc. are suitable at the C-terminus. Some researchers have speculated that the identity of the amino acid on the C-terminus would play an important role in its activity. Suetsuna (2000) separated and identified a radical scavenging peptide, Tyr-Phe-Tyr-Pro-Glu-Leu, from casein hydrolysate, and it was confirmed that the Glu-Leu on the C-terminus mainly contributed to its antioxidant activity. Kim et al. (2009) speculated that the hydrophobic property of the amino acid on the C-terminus, for example, Val and Leu, had a distinct effect on the activity, as determined from the analysis of antioxidative peptides derived from venison hydrolysate. 

McGookin, B.J. and Augustin, M.A. 1991. Antioxidant activity of casein and Maillard reaction product from casein-sugar mixtures. J. Dairy Res. 58, 313-320. 

Caseins possess significant antioxidant activity, which may be related, in part, to their hydrophobic nature (El-Negoumy, 1965 Taylor and Richardson, 1980b Allen and Wrieden, 1982a Ericksson, 1982) and orientation of potential antioxidant side-chains of constituent amino acids at the lipid interface. Brunner (1974) reported retardation of lipid oxidation in... 

Another fat-soluble vitamin, E, was found by Evans and Bishop in 1923. Pregnant rats on a defined diet (alcohol-extracted casein, cornstarch, and lard) supplemented with butter (vitamins A and D) and yeast extract (vitamin B group) produced few young because of fetal resorption. Male rats on the same diet were sterile. The disorders, which have not been identified in man, were corrected by wheat-germ oil, from which tocopherol, the active ingredient, was isolated in 1936. In spite of intensive investigations and a recognition that the vitamin is an antioxidant and destroyer of free radicals, the function of vitamin E remains obscure. 

The thiol groups of 8-lactoglobulin and proteins of the fat globule membrane are activated by heating. Most evidence indicates that thiol groups have antioxidant properties but they may also produce active oxygen species which could act as pro-oxidants under certain circumstances. The caseins are also effective antioxidants, possibly via chelation of Cu. 

OTHER COMMENTS used as a cheap solvent for resins, waxes, casein, and dyes fatty acid salts of morpholine are used as surface-active agents and emulsifiers other compounds of morpholine are useful as corrosion inhibitors, plasticizers, viscosity improvers, antioxidants, insecticides, local anesthetics and antiseptics. 

Highly oxidizable oils such as fish oils can be protected by a process known as microencapsulation, which coats the oil with a matrix of protein (gelatin, casein), carbohydrates (starch, cellulose, carboxymethylcellulose or cellulose derivatives) and lecithin. Microencapsulation provides protection against oxidation and imparts oxidative stability. The use of carboxymethylcellulose and cyclodextrins as coatings is claimed to provide better protection of oils by improved oxygen barrier properties. For special applications as nutritional supplements, fish oils enriched in n-3 PUFA are microencapsulated, in the presence of antioxidants, into a powder that is relatively stable at ambient temperatures. However, encapsulated fish oils can impart undesirable fishy taste when incorporated into food emulsions. More research and development is needed to evaluate potential applications and benefits of active packaging to increase the shelf life of fish oils and other highly oxidizable oils in foods. 

In the production of herb and spice extracts, the combination of an antioxidant and a chelating agent provides an inproved extract quality. Chelating agents are also used in dairy products, wherein their deaggregating activity for the casein complexes is often utilized in blood recovery processes to prevent clotting and in the sugar industry to facilitate sucrose crystallization, a process which is otherwise retarded by sucrose-metal complexes. 

In summary, our data clearly indicate that particularly CML, but also casein-bound CML, can activate the SOD as one of the major antioxidant enzymes via interaction with RAGE. Increased SOD activity may (1) counteract the formation of superoxide radical anions in response to RAGE-mediated NADPH-oxidase activity and may also (2) reduce the amount of AGEs that is formed from oxidative pathways. Therefore, interaction of an AGE such as CML with RAGE may activate cellular defense mechanisms against ROS. Rising levels of AGEs may, therefore, be based on a combination of the dietary intake, in vivo formation and cellular defense mechanisms. 

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