Whey thermal denaturation

Purely thermal denaturation of proteins requires much longer times collagen in moist heat below 120 °C needs 30 min to denature (Meyer et ah, 2005), wheat glutens must be subjected to 200-215 °C of dry heat for 72 min (Friedman et ah, 1987), and as mentioned above, whey proteins require at least 50 °C and 30 min for texturization without the use of extrusion processing. 

It is demonstrated here that extrusion is an effective tool for texturing whey proteins to create new functions for dairy proteins and that thermally denatured WPl is a unique ingredient that can be used in large amounts in nontraditional applications for non-TWPl. This review covers the use of extrusion texturized dairy ingredients in foods however, there are other examples of fhe successful use of this technique along with the product, TWPl in different types of nonfood applications, such as in biodegradable films, and bioplastics. 

Thermal denaturation is a traditional method for the recovery of proteins from whey as lactalbumin coagulation is optimal at pH 6 and about 90°C for 10 min (Chapter 4). 

Mulvihill, D.M. and Donovan, M. (1987) Whey proteins and their thermal denaturation A review. Irish J. Food Sci. Technoi, 11, 43-75. 

Harwalker, V. R. 1979. Comparison of physico-chemical properties of different thermally denatured whey proteins. Milchwissenschaft 34, 419-422,... 

P Resmini, L Pellegrino, JA Hogenboom, R Andreini. Thermal denaturation of whey protein in pasteurized milk. Fast evaluation by HPLC. Ital J Food Sci 3 51-62, 1989. 

Plock, J., Spiegel, T., and Kessler, H.G. (1997). Reaction kinetics of the thermal denaturation of whey protein in sweet whey concentrated by evaporation. Milchwissenschaft 53, 327-331. 

Hinrichs, J. and Rademacher, B. 2004. High pressure thermal denaturation kinetics of whey proteins. J. Dairy Res. 71(4) 480-488. 

A combination of heat and shear has been used to create whey protein particles with controlled particle size and properties. A well-known example of the use of microparticulation of thermally denatured whey protein is for the production of Simplesse 100, a whey-based fat replacer (Lieske and Konrad, 1993). Shear can be used to modulate gel properties of whey protein isolate gels. 

Anema (2008b) showed that application of combined process involving heat and high pressure to skim milk resulted in higher level of whey protein denaturation than that of heat or pressure treatment alone. High-pressure treatment alone decreased the casein micelle size, whereas the change in casein micelle size was not prominent for thermal or combined treatment. 

The dissociation of a quaternary structure or denaturation of proteins is required prior to emulsification. Therefore, casein micelles are adsorbed at an interface in a semi-intact form (Oortwijn et al., 1977). The thermal denaturation of globular proteins prior to emulsification was reported to improve the emulsifying properties. The high level of the thermally denatured whey protein fraction in mixed proteins (of denatured and undenatured proteins) increased the emulsion viscosity and coalescence stability compared with the low-level denatured fraction (Britten et al., 1994). 

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... 

Whey proteins denature at temperatures above 70°C and become insoluble and form thermally irreversible gels. 

Skelte, G.A. Anthony B.M. Reaction kinetics of thermal denaturation of whey proteins in heated Reconstituted whole milk. Journal of Agricultural and Food Chemistry, 1996, 44,422-428. 

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