Hostname: page-component-586b7cd67f-l7hp2 Total loading time: 0 Render date: 2024-11-29T19:55:40.578Z Has data issue: false hasContentIssue false
  • English
  • Français

Studies on the heat stability of milk: II. Association and dissociation of particles and the effect of added urea

Published online by Cambridge University Press:  01 June 2009

Douglas G. Dalgleish ,
Yves Pouliot  and
Paul Paquin
Douglas G. Dalgleish
Affiliation:
Hannah Research Institute, Ayr, KA6 5HL, UK
Yves Pouliot
Affiliation:
Sciences et Technologie des Aliments, Université Laval, Québec, Canada
Paul Paquin
Affiliation:
Sciences et Technologie des Aliments, Université Laval, Québec, Canada
Get access Rights & Permissions [Opens in a new window]

Summary

The sizes of the casein particles in milk heated at 130°C were measured as functions of heating time and of initial pH. The effect of adding 10 mM-urea to the milks was also studied. Turbidities of the milks before and after dispersing the caseinate particles in 8 m-urea/EDTA/β-mercaptoethanol were measured, the latter measurement giving an indication of the extent of covalent cross-linking. Urea was found to modify the behaviour of the milk: diameters of the caseinate particles were considerably altered, and the extent of covalent cross-linking was diminished. These results agree with the observation that more protein is solubilized from the casein micelles when urea is present, indicating that a competitive reaction scheme involving cross-linking in opposition to micellar dissociation may be responsible for the ultimate precipitation of milk by heat.

Type
Original Articles
Information
Journal of Dairy Research , Volume 54 , Issue 1 , February 1987 , pp. 39 - 49
Copyright
Copyright © Proprietors of Journal of Dairy Research 1987

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Andrews, A. T. 1975 Properties of aseptically packed ultra-high-temperature milk. III. Formation of polymerized protein during storage at various temperatures. Journal of Dairy Research 42 89–99CrossRefGoogle Scholar
Aoki, T. & Kako, Y. 1983 Relation between micelle size and formation of soluble casein on heating concentrated milk. Journal of Dairy Research 50 207–213CrossRefGoogle Scholar
Aoki, T., Suzuki, H. & Imamura, T. 1974 Formation of soluble casein in whey protein-free milk heated at high temperature. Milchwissenschaft 29 589–594Google Scholar
Aoki, T., Suzuki, H. & Imamura, T. 1975 Some properties of soluble casein in heated concentrated whey protein-free milk. Milchwissenschaft 30 30–35Google Scholar
Carroll, R. J., Thompson, M. P. & Melnychyn, P. 1971 Gelation of concentrated skimmilk: electron microscopic study. Journal of Dairy Science 54 1245–1252CrossRefGoogle Scholar
Cheeseman, G. C. & Knight, D. 1974 The nature of casein aggregates in heated and stored milk. Journal of Dairy Research 41 359–366CrossRefGoogle Scholar
Creamer, L. K., Berry, G. P. & Matheson, A. R. 1978 The effect of pH on protein aggregation in heated skim milk. New Zealand Journal of Dairy Science and Technology 13 9–15Google Scholar
Dalgleish, D. G., Pouliot, Y. & Paquin, P. 1987 Studies on the heat stability of milk. I. Behaviour of divalent cations and phosphate in milks heated in a stainless steel system. Journal of Dairy Research 54 29–37CrossRefGoogle Scholar
Darling, D. F. 1980 Heat stability of milk. Journal of Dairy Research 47 199–210CrossRefGoogle Scholar
Fox, P. F. 1981 a Heat-induced changes in milk preceding coagulation. Journal of Dairy Science 64 2127–2137CrossRefGoogle Scholar
Fox, P. F. 1981 b Heat stability of milk: significance of heat-induced acid formation in coagulation. Irish Journal of Food Science and Technology 5 1–11Google Scholar
Koppel, D. E. 1972 Analysis of macromolecular polydispersity in intensity correlation spectroscopy: the method of cumulants. Journal of Chemical Physics 57 4814–4820CrossRefGoogle Scholar
Kudo, S. 1980 The heat stability of milk: formation of soluble proteins and protein-depleted micelles at elevated temperatures. New Zealand Journal of Dairy Science and Technology 15 255–263Google Scholar
Morr, C. V. 1969 Protein aggregation in conventional and ultra-high-temperature heated skimmilk. Journal of Dairy Science 52 1174–1180CrossRefGoogle Scholar
Morr, C. V. 1975 Chemistry of milk proteins during food processing. Journal of Dairy Science 58 977–984CrossRefGoogle ScholarPubMed
Muir, D. D. & Sweetsur, A. W. M. 1976 The influence of naturally occurring levels of urea on the heat stability of bulk milk. Journal of Dairy Research 43 495–499CrossRefGoogle Scholar
Muir, D. D. & Sweetsur, A. W. M. 1977 Effect of urea on the heat coagulation of the caseinate complex in skim-milk. Journal of Dairy Research 44, 249–257CrossRefGoogle Scholar
Muir, D. D. & Sweetsur, A. W. M. 1977 The effect of concentration on the heat stability of skim-milk. Journal of Dairy Research 45 37–45CrossRefGoogle Scholar
Pyne, G. T. 1958 The heat coagulation of milk. II. Variations in sensitivity of casein to calcium ions. Journal of Dairy Research 25 467–474CrossRefGoogle Scholar
Rajput, Y. S., Bhavadasan, M. K. & Ganguli, N. C. 1984 Effect of urea on heat-induced acidity and milk coagulation. New Zealand Journal of Dairy Science and Technology 19 49–54Google Scholar
Schmidt, D. G. 1968 Electron-microscopic studies of the gelation of UHTST sterilized concentrated skim milk. Netherlands Milk and Dairy Journal 22 40–49Google Scholar
Singh, H. & Fox, P. F. 1985 Heat stability of milk: the mechanism of stabilization by formaldehyde. Journal of Dairy Research 52 65–76CrossRefGoogle Scholar
Sweetsur, A. W. M. & Muir, D. D. 1981 Role of cyanate ions in the urea-induced stabilization of the caseinate complex in skim-milk. Journal of Dairy Research 48 163–166CrossRefGoogle Scholar
Sweetsur, A. W. M. & White, J. C. D. 1974 Studies on the heat stability of milk protein. I. Interconversion of type A and type B milk heat-stability curves. Journal of Dairy Research 41 349–358CrossRefGoogle Scholar