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Application of polymer cross-linking theory to rennet-induced milk gels

Published online by Cambridge University Press:  01 June 2009

Donald E. Johnston
Donald E. Johnston
Affiliation:
Department of Agricultural and Food Chemistry, The Queen's University of Belfast, Belfast BT9 5PX, Northern Ireland, Department of Agriculture for Northern Ireland
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Summary

A general theory of gel formation by cross-linking of polymer molecules, orginally developed for the study of rubber vulcanization, is proposed as a model for milk gel formation. The model divides gel formation and development into 4 stages, an enzymic and a non-enzymic stage preceding gelation, then a stage of material transition from the sol to the gelled state and a stage of increase in gel strength due to internal cross-link formations. The 2 post-gelation stages overlap to a variable degree depending upon particular circumstances. Gel formation and properties are interpreted in terms of the number of initial units which combine to form the gel and the number of cross-links eventually formed by each unit. When combined with a kinetic expression for the rate of cross-link formation the time course of gel shear modulus development or of the incorporation of material into the gel may be predicted. The classical asymmetric sigmoid shape of gel shear modulus development curves results from the third stage of material transition into the gel, which in turn depends upon the number of cross-links eventually formed by each initial unit. The modulus of mature gels is found to depend upon the square of material concentration, and gel breaking strength is found to be proportional to the modulus, in agreement with the predictions of the theory.

Type
Original Articles
Information
Journal of Dairy Research , Volume 51 , Issue 1 , February 1984 , pp. 91 - 101
Copyright
Copyright © Proprietors of Journal of Dairy Research 1984

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References

REFERENCES

Beltman, H. & Lyklbma, J. 1974 Rheological monitoring of the formation of polyvinyl alcohol–congo red gels. Faraday Discussions of the Chemical Society 57 92–100CrossRefGoogle Scholar
Bereidgb, N. J. 1952 Some observations on the determination of the activity of rennet. Analyst 77 57–62Google Scholar
British Standards Institution 1963 Methods for the chemical analysis of liquid milk and cream. B.S. 1741. London: BSIGoogle Scholar
Culioli, J. & Sherman, P. 1978 Rheological aspects of the rennetting of milk concentrated by ultraflltration. Journal of Texture Studies 9 257–281CrossRefGoogle Scholar
Daloleish, D. G. 1980 Effect of milk concentration on the rennet coagulation time. Journal of Dairy Research 47 231–235CrossRefGoogle Scholar
Darling, D. F. & Van Hooydonk, A. C. M. 1981 Derivation of a mathematical model for the mechanism of casein micelle coagulation by rennet. Journal of Dairy Research 48 189–200CrossRefGoogle Scholar
Flory, P. J. 1941 Molecular size distribution in three dimensional polymers. I. Gelation. II. Trifunctional branching units. III. Tetrafunctional branching units. Journal of the American Chemical Society 63 3083–3090, 3091–3096, 3096–3100CrossRefGoogle Scholar
Flory, P. J. 1944 Network structure and the elastic properties of vulcanized rubber. Chemical Reviews 35 51–75CrossRefGoogle Scholar
Floby, P. J. 1946 Effects of molecular structure on physical properties of butyl rubber. Industrial and Engineering Chemistry 38 417–436Google Scholar
Flohy, P. J. 1947 Molecular size distribution in three dimensional polymers V. Post-gelation relationships. Journal of the American Chemical Society 69 30–35Google Scholar
Foltmann, B. 1959 On the enzymatic and the coagulation stages of the renneting process. Proceedings 15th International Dairy Congress, London 2 655–661Google Scholar
Gelman, R. A. & Gladner, J. A. 1980 Rigidity of fibrin gels as measured by quasielastic light scattering. Biopolymers 19 1259–1270CrossRefGoogle ScholarPubMed
Green, M. L., Hobbs, D. G., Morant, S. V. & Hill, V. A. 1978 Intermicellar relationships in rennet-treated separated milk. II. Process of gel assembly. Journal of Dairy Research 45 413–422CrossRefGoogle Scholar
Green, M. L. & Morant, S. V. 1981 Mechanism of aggregation of casein micelles in rennet-treated milk. Journal of Dairy Research 48 57–63CrossRefGoogle Scholar
Holter, H. 1932 [On the action of rennet]. Biochemische Zeitschrift 255 160–188Google Scholar
Kamel, B. S. & De Man, J. M. 1977 Some factors affecting gelatin gel texture evaluation by penetration testing. Journal of Texture /Studies 8 327–337CrossRefGoogle Scholar
Mitchell, J. R. 1976 Rheology of gels. Journal of Texture Studies 7 313–339CrossRefGoogle Scholar
Payens, T. A. J. 1979 Casein micelles: the colloid-chemical approach. Journal of Dairy Research 46 291–306CrossRefGoogle ScholarPubMed
Schmidt, D. G., Walstra, P. & Buchheim, W. 1973 The size distribution of casein micelles in cow's milk. Netherlands Milk and Dairy Journal 27 128–142Google Scholar
Scott Blair, G. W. & Bubnett, J. 1958 Physical changes in milk caused by the action of rennet. I. Description of apparatus for measuring rigidity moduli and internal viscosities, tests of reliability and some observations on syneresis. Journal of Dairy Research 25 297–303CrossRefGoogle Scholar
Scott Blair, G. W. & Bubnett, J. 1959 Physical changes in milk caused by the action of rennet. V. Effects of varying concentrations of milk powder and of low-temperature pretreatment. Journal of Dairy Research 26 144–150CrossRefGoogle Scholar
Scott Blair, G. W. & Burnett, J. 1963 An equation to describe the rate of setting of blood and milk. Biorheology 1 183–191CrossRefGoogle Scholar
Szczesniak, A. S. & Macallisteb, R. V. 1964 Study of gelatin gels and the effect of urea on their formation. Journal of Applied Polymer Science 8 1391–1401CrossRefGoogle Scholar
Tuszyński, W. B. 1971 Akinetic model oftheclotting of casein byrennet. Journal of Dairy Research 38 115–125CrossRefGoogle Scholar
White, J. C. D. & Davies, D. T. 1966 The stability of milk proteins to heat. III. Objective measurement of heat stability of milk. Journal of Dairy Research 33 93–102CrossRefGoogle Scholar