Lactoglobulin thermal denaturation

Harwalker, V. R. 1978. Application of differential scanning calorimetry to the study of thermal denaturation of (3-lactoglobulin in solution. J. Dairy Sci. 61 (suppl. 1), 107. 

The conformational changes in /J-lactoglobulin during foaming and thermal denaturation were studied by H NMR and 2H exchange spectroscopy.92-93 The properties of three equine whey proteins, alpha-lactoalbumin, /J-lactoglobulin, and lysozyme, have been studied and compared with those of the corresponding bovine milk.94... 

Figure 9.16 Stages in the thermal denaturation of /3-lactoglobulin (from Mulvihill and Donovan, 1987).

Ruyol, R Rtrez, M.D. Reiro, J.M. Calvo, M. Effect of retinol and fatty acid binding to bovine P-lactoglobulin on its resistance to thermal denaturation. J. Dairy Sci. 1994, 77 (6), 1494. 

KH Park, DB Lund. Calorimetric study of thermal denaturation of P-lactoglobulin. J Dairy Sci 67 1699-1706 (1984). 

Tolkach, A., Kulozik, U. (2007). Reaction kinetic pathway of reversible and irreversible thermal denaturation of p-lactoglobulin. Le Lait, 87, 301-315. 

Lactoglobulin With a denaturation temperature of 78°C, /3-lacto-globulin is the least denaturable of the serum proteins (Table 11.2). It exhibits a second thermal change near 140°C caused by a breakdown of disulfide bonds and additional unfolding of the molecule (de Wit 1981 Watanabe and Klostermeyer 1976). A change in pH between 6 and 7.5 shifts denaturation between 78° and 140°C, the total denaturation at the two temperatures being nearly constant. pH 6 favors dena-... 

D. Thermal Modifications of Structure and Co-denaturation of a-lactalbumin and p-lactoglobulin... 

Although less frequently discussed, heat processes often influence the textures and chemistries of the intermediate and end products, and thermal treatments are not without consequences on milk proteins that are denatured. Denaturation of proteins occurs under precise conditions of pH, temperature and ionic strength leading to their unfolding. Denaturation is significantly slower when proteins are near their isoelectric point. Only (3-lactoglobulin is irreversibly denatured at pH 7 and 70°C a-lactalbumin is denatured at pH 6.7 and 65°C. Aggregation of these proteins, besides hydrophobic... 

Bertrand-Harb, C., Baday, A., Dalgalarrondo, M., Chobert, J.-M., and Haertle, T. 2002. Thermal modifications of structure and co-denaturation of a-lactalbumin and (3-lactoglobulin induce changes of solubility and susceptibility to proteases. Nahrung 46, 283 —289. 

Tolkach, A., and Kulozik, U. (2005). Optimization of thermal pretreatment conditions for the separation of native a-lactalbumin from whey protein concentrates by means of selective denaturation of p-lactoglobulin. J. Food Set., 70(9), 557-566. 

It should be noted that ultrasonic technology is a non-thermal process and hence very little changes to the physical and functional properties of dairy system is observed due to sonication. In most studies, the processing time required is a few seconds to less than a minute. In order to evaluate the effect of sonication on the constituents of milk, Chandrapala et al. [85] and Shanmugam et al. [86] carried out extensive research in recent years. Their studies have shown that sonication of a dairy system causes very little changes to the physical properties of whey proteins. They observed reversible changes to partial denaturation of whey proteins. In order to see the effect, the constituents of whey proteins, namely, pure- and 3 1 mixtures of p-Lactoglobulin (P-LG) and a-Lactalbumin (a-LA)... 

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