If you need an accessible version of this item please contact JSTOR User Support

Thermal Denaturation and Aggregation of Whey Proteins

M. Donovan and D. M. Mulvihill
Irish Journal of Food Science and Technology
Vol. 11, No. 1 (1987), pp. 87-100
Stable URL: http://www.jstor.org/stable/25558155
Page Count: 14
  • Download PDF
  • Cite this Item

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support
Thermal Denaturation and Aggregation of Whey Proteins
Preview not available

Abstract

The denaturation of whey protein in a rennet casein whey, as measured by protein rendered insoluble at pH 4.5 and reactive thiol groups, increased slowly on heating at 60 and 70°C and increased very quickly on heating at 80 and 90°C. This shows that whey protein denaturation is a co-operative process with a large thermal coefficient. Electrophoresis showed that the relative denaturation rates of the individual whey proteins differed. The order of heat resistance found was proteose peptone >α-lactalbumin>β-lactoglobulin>bovine serum albumin >immunoglobulin. The contribution of the individual whey proteins to the total protein denaturation is shown. The thermodenaturation of the total whey protein increased with increasing pH in the range 4.5-7.0 and electrophoresis showed that the thermal response of the individual whey proteins to pH differed. Greatest denaturation of β-lactoglobulin occurred at high pH, bovine serum albumin was most resistant at high pH while the thermal denaturation of α-lactalbumin was relatively independent of pH. Thermal precipitation was also found to be pH dependent with greatest aggregation occurring in the pH range 4.5-5.5. That thermal precipitation of whey proteins is influenced mainly by electrostatic charge is shown by the increased precipitation at high pH on the neutralization of the high negative charge of denatured protein molecules by the addition of Ca²⁺

Page Thumbnails

  • Thumbnail: Page 
87
    87
  • Thumbnail: Page 
88
    88
  • Thumbnail: Page 
89
    89
  • Thumbnail: Page 
90
    90
  • Thumbnail: Page 
91
    91
  • Thumbnail: Page 
92
    92
  • Thumbnail: Page 
93
    93
  • Thumbnail: Page 
94
    94
  • Thumbnail: Page 
95
    95
  • Thumbnail: Page 
96
    96
  • Thumbnail: Page 
97
    97
  • Thumbnail: Page 
98
    98
  • Thumbnail: Page 
99
    99
  • Thumbnail: Page 
100
    100