Hostname: page-component-76fb5796d-45l2p Total loading time: 0 Render date: 2024-04-25T21:20:05.568Z Has data issue: false hasContentIssue false
  • English
  • Français

Relationship between ethanol stability of bovine milk and natural variations in milk composition

Published online by Cambridge University Press:  01 June 2009

William J. Donnelly  and
David S. Horne
William J. Donnelly
Affiliation:
Agricultural Institute, Moorepark Research Centre, Fermoy, Co. Cork, Irish Republic
David S. Horne
Affiliation:
Hannah Research Institute, Ayr KA6 5HL, UK
Get access Rights & Permissions [Opens in a new window]

Summary

Several ionic components of ultrafiltrate were measured in bulk and individual cow milks and an assessment was made of their relationship with the parameters of the corresponding ethanol (EtOH) stability/pH profiles. From linear regression analysis the strongest relationships (P < 0·001) were between soluble salt balance [expressed as (Ca+Mg) minus (Pi+Cit) or as the ratio to (Pi+Cit)] and pK (correlation coefficient, γ ∼ 0·82) or Smax, the maximum stability at high pH (γ ∼–0·72), and between Pi and pK(γ = –0·84)or Smax (γ = –0·61). These relationships agree with the view that the parameters of the EtOH stability/pH profile are determined by pH-induced changes in concentration of divalent cations. Natural variations in these parameters may be attributed to variations in relative concentrations of divalent cations and their chelators. EtOH stabilities at the natural pH of bulk milks from winter/spring- and autumn-calving animals were lowest in early and late lactation. The most important contributory factors appeared to be a high salt balance ratio in late lactation and a low natural milk pH in early lactation. The main component responsible for variable salt balance ratio was usually soluble Pi. Decrease in EtOH stability at the natural pH of late lactation milks reflected a more general change in the characteristics of the EtOH stability/pH profile, seen as an increase in pK and, in extreme cases, a decrease in Smax and profile gradient.

Type
Original Articles
Information
Journal of Dairy Research , Volume 53 , Issue 1 , February 1986 , pp. 23 - 33
Copyright
Copyright © Proprietors of Journal of Dairy Research 1986

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

Barry, J. G. & Donnelly, W. J. 1980 Casein compositional studies. 1. The composition of casein from Friesian herd milks. Journal of Dairy Research 47 71–81CrossRefGoogle Scholar
Davies, D. T. & White, J. C. D. 1958 The relation between the chemical composition of milk and the stability of the caseinate complex. II. Coagulation by ethanol. Journal of Dairy Research 25 256–266CrossRefGoogle Scholar
Donnelly, W. J., Barry, J. G. & Buchheim, W. 1984 Casein micelle composition and syneretic properties of late lactation milk. Irish Journal of Food Science and Technology 8 121–130Google Scholar
Holt, C. 1982 Inorganic constituents of milk. III. The colloidal calcium phosphate of cow's milk. Journal of Dairy Research 49 29–38CrossRefGoogle ScholarPubMed
Holt, C, Daloleish, D. G. & Jenness, R. 1981 Calculations of the ion equilibria in milk diffusate and comparison with experiment. Analytical Biochemistry 113 154–163CrossRefGoogle ScholarPubMed
Holt, C. & Jenness, R. 1984 Interrelationships of constituents and partition of salts in milk samples from eight species. Comparative Biochemistry and Physiology A 77 275–282CrossRefGoogle ScholarPubMed
Holt, C. & Muir, D. 1979 Inorganic constituents of milk. 1. Correlation of soluble calcium with citrate in bovine milk. Journal of Dairy Research 46 433–439CrossRefGoogle Scholar
Horne, D. S. & Parker, T. G. 1980 The pH sensitivity of the ethanol stability of individual cow milks. Netherlands Milk and Dairy Journal 34 126–130Google Scholar
Horne, D. S. & Parker, T. G. 1981 a Factors affecting the ethanol stabiity of bovine milk. I. Effect of serum phase components. Journal of Dairy Research 48 273–284CrossRefGoogle Scholar
Horne, D. S. & Parker, T. G. 1981 b Factors affecting the ethanol stability of bovine milk. II. The origin of the pH transition. Journal of Dairy Research 48 285–291CrossRefGoogle Scholar
Horne, D. S. & Parker, T. G. 1981 c Factors affecting the ethanol stability of bovine milk. IV. Effect of forewarming. Journal of Dairy Research 48 405–415CrossRefGoogle Scholar
International Dairy Federation 1967 Standard 42Google Scholar
Keogh, M. K., Kelly, P. M., O'keeffe, A. M. & Phelan, J. A. 1982 Studies of milk composition and its relationship to some processing criteria. II. Seasonal variation in the mineral levels of milk. Irish Journal of Food Science and Technology 6 13–27Google Scholar
Pyne, G. T. & McGann, T. C. A. 1960 The colloidal phosphate of milk. II. Influence of citrate. Journal of Dairy Research 27 9–17CrossRefGoogle Scholar
Sommer, H. H. & Binney, T. H. 1923 A study of the factors that influence the coagulation of milk in the alcohol test. Journal of Dairy Science 6 176–197CrossRefGoogle Scholar
White, J. C. D. & Davies, D. T. 1958 The relation between the chemical composition of milk and the stability of the caseinate complex. 1. General introduction, description of samples, methods and chemical composition of samples. Journal of Dairy Research 25 236–255CrossRefGoogle Scholar
White, J. C. D. & Davies, D. T. 1963 The determination of citric acid in milk and milk sera. Journal of Dairy Research 30 171–189CrossRefGoogle Scholar
Wood, G. B., Reid, D. S. & Elvin, R. 1981 Calculation by computer of individual concentrations in a simulated milk salt solution: I. Journal of Dairy Research 48 77–83CrossRefGoogle Scholar