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Casein compositional studies. III. Changes in Irish milk for manufacturing and role of milk proteinase

Published online by Cambridge University Press:  01 June 2009

William J. Donnelly  and
J. Gerard Barry
William J. Donnelly
Affiliation:
The Agricultural Institute, Moorepark Research Centre, Fermoy, Co. Cork, Irish Republic
J. Gerard Barry
Affiliation:
The Agricultural Institute, Moorepark Research Centre, Fermoy, Co. Cork, Irish Republic
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Summary

The composition of casein in Irish milk for manufacturing was examined throughout the year. Large changes in composition were observed in the final quarter of the year as a result of the influence of late lactation when the proportion of αs- and β-caseins declined and the proportion of κ- and γ-caseins and of minor casein components increased. Similar changes in casein composition were induced by treatment of milk with porcine plasmin. The activity of plasmin-like milk proteinase in milk was quantified from the rate of conversion of added [14C]β-casein to [14C]γ-caseins. This activity was considerably higher in a late lactation milk than in a mid lactation milk and was ∼ 20 times higher at 37 °C than at 4 °C. It was concluded that casein compositional changes in late lactation were largely the result of proteolysis of individual caseins by plasmin-like milk proteinase.

Type
Original Articles
Information
Journal of Dairy Research , Volume 50 , Issue 4 , November 1983 , pp. 433 - 441
Copyright
Copyright © Proprietors of Journal of Dairy Research 1983

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References

REFERENCES

Barry, J. G. & Donnelly, W. J. 1980 Casein compositional studies. I. The composition of casein from Friesian herd milks. Journal of Dairy Research 47 71–81CrossRefGoogle Scholar
Barry, J. G. & Donnelly, W. J. 1981 Casein compositional studies. II. The effect of secretory disturbance on casein composition in freshly drawn and aged bovine milks. Journal of Dairy Research 48 437–446CrossRefGoogle Scholar
Davies, D. T. & Law, A. J. R. 1977 The composition of whole casein from the milk of Ayrshire cows. Journal of Dairy Research 44 447–454CrossRefGoogle Scholar
Davies, D. T. & Law, A. J. R. 1980 The content and composition of protein in creamery milks in south-west Scotland. Journal of Dairy Research 47 83–90CrossRefGoogle Scholar
De Rham, O. & Andrews, A. T. 1982 The role of native milk proteinase and its zymogen during proteolysis in normal bovine milk. Journal of Dairy Research 49 577–585CrossRefGoogle Scholar
Donnelly, W. J., Barry, J. G. & Richardson, T. 1980 14C-Methylated β-casein as a substrate for plasmin and its application to the study of milk protein transformations. Biochimica et Biophysica Acta 626 117–126CrossRefGoogle Scholar
Phelan, J. A., O'keeffe, A. M., Keogh, M. K. & Kelly, P. M. 1982 Studies of milk composition and its relationship to some processing criteria. Irish Journal of Food Science and Technology 6 1–11Google Scholar
Reimerdes, E. H. & Herlitz, E. 1979 The formation of γ-caseins during cooling of raw milk. Journal of Dairy Research 46 219–221CrossRefGoogle ScholarPubMed