Rheology of milk gels

Gels are viscoelastic bodies, the rheological properties of which can be described by two parameters, the storage modulus (G, which is a measure of its elasticity) and the loss modulus (G , which is a measure of its viscous nature). The combined viscoelastic modulus (G ) is a measure of the overall resistance of a gel to deformation. These moduli are often highly dependent on the time-scale of deformation. Another important parameter of a food gel is its yield stress. 

Although the gelation properties of whey proteins are of great importance in many foods (Mulvihill, 1992) and it is possible to form a weak gel in creams by the formation of a continuous network of fat globules, most important milk gels are those involving casein micelles which can be made to form a gel matrix either by isoelectric precipitation (acid-induced gel) or by the action of a proteolytic enzyme (rennet-induced gel). Both gel types 

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Olson, N. F. and Bottazzi, V. 1977. Rheology of milk gels formed by milk-clotting enzymes. J. Food Sci. 42, 669-673. 

Lucey, J.A., Tamehana, M., Singh, H., and Munro, P.A. (2000). Rheological properties of milk gels formed by a combination of rennet and glucono-delta-lactone. J. Dairy Sci. 67, 415 27. 

This study has shown that the process used to coagulate milk has a broad effect on fat globule-protein interactions and on the molecular structure of the gel. In addition we have shown that the different molecular structures of the three coagula correspond to different rheological properties. 

Bikker, J.F., Anema, S.G., Li, Y., Hill, J.P. (2000). Rheological properties of acid gels prepared front heated milk fortified with whey protein mixtures containing the A, B and C variants of p-lactoglobulin. International Dairy Journal, 10, 723-732. 

Kampf, N. and Nussinovitch, A. 1997. Rheological characterization of carrageenan soy milk gels. Food Hydrocoil. 11 261 -269. 

Rosenberg, M. 2000. Applications for fractionated milk fat in modulating rheological properties of milk and whey composite gels. Aust. J. Dairy Technol. 55, 56-60. 

Anema, S.G., Lee, S.K., Lowe, E.K., and Klostermeyer, H. (2004). Rheological properties of acid gels prepared from heated pH-adjusted skim milk. J. Agric. Food Chem. 52, 337-343. 

Castillo, M., Lucey, J.A., and Payne, F A. (2006). The effect of temperature and inoculum concentration on rheological and light scatter properties of milk coagulated by a combination of bacterial fermentation and chymosin cottage cheese-type gels. Int. Dairy J. 16, 131-146. 

Dickinson, E., Hong, S.-T., and Yamamoto, Y. 1996. Rheology of heat-set emulsion gels containing beta-lactoglobulin and small-molecule surfactants. Neth. Milk Dairy J. 50 199-207. 

Faergemand, M., and Qvist, K.B. (1997). Transglutaminase Effect on rheological properties, microstructure and permeability of set style add skim milk gel. Food Hydrocolloids 11, 287-292. 

Xiong, Y.L.L., Aguilera, J.M., and Kinsella, J.E. (1991). Emulsified milkfat effects rheology of acid-induced milk gels. J. Food Sci. 56,918-925. 

Zoon, P., Van Vliet, T., and Walstra, P. (1988). Rheological properties of rennet-induced skim milk gels. 1. Introduction. Neth. Milk Dairy ]. 42, 249-269. 

Schellhaass, S. M., and Morris, H. A. (1985). Rheological and scanning electron microscopic examination of skim milk gels obtained by fermenting with ropy and non-ropy strains of lactic acid bacteria. Food Microstruct. 4, 279-287. 

According to the consistency, a distinction is made between stiff, gel-like products, stirred, creamy products, and drinkable, flowable products. The thermal pretreatment of milk influences the rheological properties of the products as described in section 10.1.2.1.3. The keeping time of sour milk products can be increased if they are produced and filled under aseptic conditions or produced under normal conditions but subsequently heat treated. 

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