Studies on rheological properties of stirred milk gels made from milk with defined genetic variants of kappa-casein and beta-lactoglobulin
Allmere, T.; Andren, A.; Lindersson, M.; Bjorck, L.
International Dairy Journal 8(10-11): 899-905
ISSN/ISBN: 0958-6946 Accession: 011414146
The rheological properties of acidified milk gels made from milk with defined genetic variants of kappa-casein and beta-lactoglobulin have been investigated. Gels were prepared from skim milk after heating for 4 min at 90degreeC by acidification with glucono-delta-lactone and gentle stirring after holding for 24 h at 20degreeC. Stirred acidified milk gels were then kept at 6degreeC for 96 h and thereafter measured for the rheological properties using a Bohlin VOR Rheometer. The milk gels containing only the B variant of beta-lactoglobulin (homozygous cows) were found to have a significantly higher elastic modulus as compared to milk gels containing both beta-lactoglobulin A and B or only A. An explanation could be that more beta-lactoglobulin B had aggregated with the casein micelles, since a strong correlation was found between the loss of native beta-lactoglobulin in the milk serum and the gel firmness. No correlation was found between gel firmness and any of the kappa-casein genetic variants, dry matter content and the total protein concentration, respectively. Furthermore, viscous properties did not vary between the acidified milk gels in this experiment.