Milk protein mutations for better quality cheese
cheese yield, composition and quality, confirming recent findings
from researchers in New Zealand.
Ng-Kwai-Hang at McGill University and his research team have found that small changes or mutations in the DNA of certain genes lead to changes in the protein which results in dramatic changes in the cheese.
Their findings show that a mutation in the particular protein, the kappa-casein, is associated with a higher yield of cheese 'and one which is better quality'.
They believe their investigations will lead to more efficient cheese production and better quality cheese.
According to Ng, in addition to the two genetic variants for kappa casein, there are about 50 known milk protein gene variants that can have diverse effects on dairy product production.
" Because the genetic variants are inherited according to simple Mendelian rules, it is possible to breed for specific variants," says Ng. "We are seeing this already where breeding programs are in place to increase the frequency of the B type of kappa-casein in cow populations in order to improve the milk quality and its cheese making characteristics."
Their findings follow swiftly on from reports last month that scientists in New Zealand had created cows genetically modified to produce high-protein milk for the cheese industry.
According to the UK New Scientist journal, this is the first time cow's milk has been engineered to improve its quality, rather than to contain profitable pharmaceuticals.
"The cows possess additional copies of genes for two proteins, beta and kappa casein. As a result, their milk contains between up to 20 per cent more beta-casein and twice the amount of kappa-casein as milk from ordinary cows," writes the journal.
The modification should allow cheese-makers to produce more cheese from the same volume of milk. The manufacturing process should also be quicker, due to the faster clotting times associated with the higher protein levels.
"Basically, cheese is casein," Goötz Laible, who led the work at the Ruakura Research Centre in Hamilton, is quoted as saying in the New Scientist report.
"An increase in casein would certainly be of great value to the dairy industry, because farmers are paid on the basis of how much casein is produced in the milk."
Laible's team created a number of transgenic cell lines, each containing up to 39 additional copies of the casein genes. These were fused with cow eggs, and the cloned embryos produced were implanted in cows. Of 11 healthy offspring, nine produced increased amounts of casein.
