Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-18T06:53:26.490Z Has data issue: false hasContentIssue false

Influence of 2-mercaptoethanol on heat stability of concentrated whey-protein-free milk and formation of soluble casein

Published online by Cambridge University Press:  01 June 2009

Takayoshi Aoki
Affiliation:
Animal Products Processing Research Laboratory, Faculty of Agriculture, Kagoshima University, Kagoshima 890, Japan
Yoshitaka Kako
Affiliation:
Animal Products Processing Research Laboratory, Faculty of Agriculture, Kagoshima University, Kagoshima 890, Japan

Summary

The heat coagulation time (HCT) of concentrated whey-protein-free (WPF) milk measured at 120 and 130 °C was reduced to by addition of 5–20 mM-2-mercaptoethanol (ME). However, although the amount of soluble casein formed on heating was doubled by addition of ME, the shape of the HCT–pH profile was affected only slightly. The proportion of κ-casein in the soluble casein from heated concentrated WPF milk containing ME was very high, though it was somewhat lower than that of the soluble casein from heated concentrated WPF milk containing no ME. No solubilization of colloidal Ca phosphate was observed in either unheated or heated concentrated WPF milk on addition of ME. These facts suggest that ME probably promotes the formation of soluble casein with release of κ-casein from micelles on heating, thus destabilizing the casein micelles.

Type
Original Articles
Copyright
Copyright © Proprietors of Journal of Dairy Research 1984

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

Allen, R. J. L. 1940 The estimation of phosphorus. Biochemical Journal 34 858865CrossRefGoogle ScholarPubMed
Aoki, T., Hatanaka, C. & Imamura, T. 1977 Large casein micelles and soluble casein in heated concentrated whey protein-free milk. Agricultural and Biological Chemistry 41 23492355.Google Scholar
Aoki, T. & Kako, Y. 1983 Relation between micelle size and formation of soluble casein on heating concentrated milk. Journal of Dairy Research 50 207213.CrossRefGoogle Scholar
Aoki, T. & Kako, Y. 1984 Effect of formaldehyde on the heat stability of concentrated milk and formation of soluble casein. Agricultural and Biological Chemistry 48 10171021.Google Scholar
Aoki, T., Suzuki, H.Imamura, T. 1974 Formation of soluble casein in whey protein-free milk heated at high temperature. Milchwissenschaft 29 589594.Google Scholar
Aoki, T., Suzuki, H. & Imamura, T. 1975 Some properties of soluble casein in heated concentrated whey protein-free milk. Milchwissenschaft 30 3035Google Scholar
Beeby, R. 1964 The presence of sulphydryl groups in κ-casein. Biochimica et Biophysica Acta 82 418419CrossRefGoogle Scholar
Carpenter, K. J. & Booth, V. H. 1973 Damage to lysine in food processing: its measurement and significance. Nutrition Abstracts & Reviews 43 423451.Google Scholar
Fox, P. F. 1980 Heat-induced changes in milk preceding coagulation. Journal of Dairy Science 64 21272137.CrossRefGoogle Scholar
Fox, P. F. 1982 Heat-induced coagulation of milk. In Developments in Dairy Chemistry. Vol 1. Proteins pp. 189228 (Ed. Fox, P. F.) London: Applied Science Publishers Ltd.Google Scholar
Fox, P. F. & Morrissey, P. A. 1977 Reviews of the progress of Dairy Science: the heat stability of milk. Journal of Dairy Research 44 627646.CrossRefGoogle Scholar
Holt, C., Muir, D. D. & Sweetscr, A. W. M. 1978 The heat stability of milk and concentrated milk containing added aldehydes and sugars. Journal of Dairy Research 45 4752.CrossRefGoogle Scholar
Janolino, V. G. & Swaisoood, H. E. 1975 Isolation and characterization of sulfhydryl oxidase from bovine milk. Journal of Biological Chemistry 250 25322538.CrossRefGoogle ScholarPubMed
Morr, C. V., Josephson, R. V., Jenness, R. & Manning, P. B. 1971 Composition and properties of submicellar casein complex in colloidal phosphate-free skimmilk. Journal of Dairy Science 54 15551563.CrossRefGoogle Scholar
Muir, D. D., Sweetsur, A. W. M. & Holt, C. 1979 The synergic effect of urea and aldehydes on the heat stability of concentrated skim-milk. Journal of Dairy Research 46 381384.CrossRefGoogle Scholar
Pepper, C. & Farrell, H. M. J. 1982 Interaction leading to formation of casein submicelles. Journal of Dairy Science 65 22592266.CrossRefGoogle Scholar
Rose, D. 1963 Heat stability of bovine milk. Dairy Science Abstracts 25 4552.Google Scholar
Rose, D. 1968 Relation between micellar and serum casein in bovine milk. Journal of Dairy Science 51 18971902CrossRefGoogle Scholar
Rose, D., Davies, D. T. & Yaguchi, M. 1969 Quantitative determination of the major components of casein mixtures by column chromatography on DEAE-cellulose. Journal of Dairy Science 52 811CrossRefGoogle Scholar
Shalabi, S. I. & Fox, P. F. 1982 Heat stability of milk: influence of cationic detergents on pH sensitivity. Journal of Dairy Research 49 597605CrossRefGoogle ScholarPubMed