Thermal denaturation of α-lactalbumin and β-lactoglobulin in cheese whey: effect of total solids concentration and pH
- 1 January 1979
- journal article
- Published by Cambridge University Press (CUP) in Journal of Dairy Research
- Vol. 46 (1), 103-111
- https://doi.org/10.1017/s0022029900016903
Abstract
SUMMARY Measurements of residual native protein remaining after heat treatment of cheese whey have been made using quantitative polyacrylamide gel electrophoresis. The results have been expressed in terms of kinetic constants. The effect of concentration was investigated up to 3 times the normal total solids content, dialysis treatments were used to study the effect of non-protein constituents, and the effect of pH was studied at pH 4, 6 and 9. The results indicated that increased total solids (TS) concentration slowed the denaturation of β-lactoglobulin A and B (β-lg A, β-lg B) but hastened the denaturation of α-lactalbumin (α-la). However, increased lactose concentration slowed the denaturation of both α-la and β-lg, perhaps by preventing formation of heat-induced complexes. Increased Ca concentration, up to 0.4 mg/ml, tended to slow the denaturation of both proteins, but further increase in Ca up to 0.9 mg/;ml produced little effect. The rate of denaturation of both α-la and β-lg was slower at pH 4 than at pH 6 or 9, and was probably slowest at the isoelectric point. However, not all the changes associated with pH could be explained in terms of net molecular electrostatic charge. The genetic variants of ′β-lg showed different heat stabilities – below 90 °C β-lgA was more stable than β-lgB, but above 90 °C the situation was reversed at all TS concentrations, and pH 6. However, at pH 4 and 9, °-lgA was less stable than °-lgB over the entire temperature range at normal concentration.Keywords
This publication has 19 references indexed in Scilit:
- Whey protein denaturation in heated milk and cheese wheyJournal of Dairy Research, 1979
- The quantitative measurement of whey proteins using polyacrylamide-gel electrophoresisJournal of Dairy Research, 1976
- The precipitation of proteins by carboxymethyl celluloseJournal of Dairy Research, 1975
- DEMINERALIZATION OF UNTREATED COTTAGE CHEESE WHEY BY ELECTRODIALYSISJournal of Food Science, 1973
- "Ferripolyphosphate" as a whey protein precipitantJournal of Agricultural and Food Chemistry, 1972
- Inter- and intramolecular interactions of α-lactalbumin VII. The hydrogen ion titration curve of α-lactalbuminBiochimica et Biophysica Acta (BBA) - Protein Structure, 1967
- Comparison de la thermodénaturation des β-lactoglobulines A et B à pH 6.85Biochimica et Biophysica Acta (BBA) - Biophysics including Photosynthesis, 1965
- Deviations from the Arrhenius equationQuarterly Reviews, Chemical Society, 1964
- The isolation and amino acid composition of two peptides from chymotryptic digests of β-lactoglobulins A and BArchives of Biochemistry and Biophysics, 1962
- Solubility transformation of α-lactalbuminArchives of Biochemistry and Biophysics, 1956