Micellization of casein‐graft‐dextran copolymer prepared through Maillard reaction

Abstract

Casein is almost insoluble at around pH 4.6, which is its isoelectric point (pI). Grafting copolymer, casein-g-dextran, was prepared through the Amadori rearrangement of the Maillard reaction. The copolymer has a reversible pH sensitive property: micellization at the pI of casein forming a casein core and dextran shell structure and dissociation when pH differs from the pI. The micelles produced at pH 4.6 have a spherical shape and their size is dependent on the Maillard reaction: reaction time, molar ratio of casein to dextran, and molecular weight of dextran used. Typically, the hydrodynamic diameter of the micelles is about 100 nm and the critical micelle concentration is about 10 mg/L. The micelles are very stable in aqueous solution and can be stored as lyophiled powder. The micelles are able to encapsulate hydrophobic compounds such as pyrene.

Acidic solution properties of β-casein-graft-dextran copolymer prepared through Maillard reaction

“…These results are in agreement with the value of around pH 5.0, the published isoelectric point [34] and the calculated overall neutrality of β-casein [35]. The very close zero potential pH values of β-casein and β-casein-graft-dextran copolymer imply that the Maillard reaction was controlled in its early stage and aminoketose-the Amadori product was mainly obtained [13,26].…”

“…Casein-graft-dextran 35 kDa with high graft degree (molar ratio of casein to 35 kDa dextran 1:8, 20 h Maillard reaction) was also used to study its emulsifying properties at pH 4.6 and 8.0. The limit of the Maillard reaction time is 20 h for casein [26], and 24 h for β-casein in the condition we used to avoid the side reaction, that is, the graft degree of the high-graft casein and β-casein copolymers used in emulsifying study is the maximum. All the copolymer solutions were prepared freshly to avoid the further aggregation or dissociation as discussed above.…”

“…Our previous study found that casein-dextran conjugates prepared by the Maillard reaction did not dissolve in single molecules but formed micelles in acidic solution [26]. Compared to casein, β-casein is more hydrophilic and it has definite composition.…”

Casein nanoparticles as carriers for the oral delivery of folic acid

“…In this context, three main approaches can be applied. The first one is based on the copolymerization of casein with synthetic polymers such as acrylic acid (Zhen, Wang, Xie, Wu, & Jiang, 2013) or dextran (Pan et al, 2006). The second one is based on the formation of nanoparticles via electrostatic complexation between the protein and polysaccharides, including Arabic gum (Ye, Flanagan, & Singh, 2006) or chitosan (Anal, Tobiassen, Flanagan, & Singh, 2008).…”

Functional properties of milk proteins as affected by Maillard reaction induced oligomerisation

“…Diminutions of the amounts of available lysine directly reflect the modification of e-amino groups of basic amino acids upon a Maillard reaction induced addition of sugar molecules to proteins in initial reaction stages. Thus, lysine and arginine modifications were reported for casein/lactose (Scaloni et al, 2002), casein/dextran (Pan, Mu, Hu, Yao, & Jiang, 2006), caseinate/glucose (Gu et al, 2009;Oliver et al, 2006a), caseinate/lactose (Oliver et al, 2006b), caseinate/pectin (Al-Hakkak & Kavale, 2002), caseinomacropeptide/lactose (Moreno, López-Fandiño, & Olano, 2002), b-lactoglobulin/lactose (Chevalier, Chobert, Mollé, et al, 2001;Fenaille, Morgan, Parisod, Tabet, & Guy, 2004;Morgan, Molle, et al, 1999), total milk protein/lactose (De Block et al, 2003) and whey protein/maltodextrin Maillard products (Akhtar & Dickinson, 2007). A modification degree of lysine of up to 100% was detected post Maillard reaction (60°C, 67% r.h., 48 h) of sodium caseinate/glucose mixtures, of up to 80% post Maillard reaction (60°C, 67% r.h., 24 h) of sodium caseinate/lactose mixtures (Oliver et al, 2006b).…”