• altitude differences
• fatty acids
• heavy metals
• minerals
• monthly variations
• protein fractions
• Qinghai plateau
• Yak milk
• yak milk cheese

As was showed in the results of this thesis, yak milk has a gross composition that is very different from milk Holstein cow breed, the most diffused cow breed in the world. In fact, yak milk is particularly rich of protein, casein and fat with respect to the cow milk. Also mineral content shows suitable characteristics; in particular, especially the milk from higher yak farms shows higher contents of both colloidal and soluble calcium and phosphorus, so also total calcium and phosphorus are higher. These properties characterize a milk that can constitute a very interesting raw material for the production of cheese.
The fat fraction of yak milk, now is often not used for food, but for Tibet Buddhism temples, to be burned for gods or to prepare some very beautiful sculptures made with yak butter. But this fraction can have also very interesting peculiarities: due to the very high altitude, the fat of these animals has a higher content of polyunsaturated fatty acids, like CLA, that exerts very beneficial effects on human health: for this reason, the yak milk could be used to produce a yak cheese with nutraceutical properties.
Moreover, this can be a solution for the problem of maintain the cold chain for yak milk; the technology of refrigeration, in this region, is not particularly developed (only in the capital) so the farmer could preserve the milk for a long time with its transformation in cheese.
We have chosen to analyse yak milk samples from different farm in different part of the province and located at different altitude, to have a picture more complete of the situation. In the research, we have found a certain variability among herds, and this is a sign that for the future yak milk quality can be improved, both improving management conditions and to improve the genetic of the animals.
The research begun with this thesis will have a continuation in the future collaboration aimed to prepare yak cheese; at the beginning it will be a fresh, soft cheese mainly made with acid coagulation, that is easier to produce, and that surely could meet the approval of the Chinese population, but with the intention to study the possibility of producing more difficult cheeses, for example of Caciotta type. Then, if it will be possible to build a cold chain at the farms, as exists for yoghurt in the capital Xining, it will be possible also to produce some cheeses like Mozzarella or Crescenza, that can surely meet the approval of Chinese people.