Early Bronze Age cheese recipe reconstructed
According to the scientist’s interpretation, this may have been instrumental in the spread of cattle herding on a large scale throughout Asia. “The method of making this kefir cheese is simple; it doesn’t spoil or turn rancid quickly. So the cheese is extremely well suited to mass production.” As a precursor to the cheese, the process of fermentation with kefir grains also produces the probiotic milk drink known as kefir. Both products contain hardly any lactose – ideal for the population groups living in Asia, most of which are lactose intolerant.
|The "Beauty of Xiaohe": the approx. 4,000 year-old mummy of a woman|
from Western China [Credit: Y. Liu, Y. Yang]
“We never actually had archaeology on our radar screen. We just kind of stumbled across it thanks to an e-mail enquiry sent by Chinese archaeologist Yimin Yang,” says Shevchenko. Yang had come up with the idea of having his finds analysed with ultramodern quantitative proteomics methods, whereupon he sent the scientists in Dresden the first cheese fragments. Before they could proceed, they had to develop methods of identifying proteins from organisms whose DNA had not yet been sequenced.
The projects are therefore truly pioneering and demonstrate most notably that quantitative proteomics is not only suitable for use in biomedical research, but could also represent a promising method for archaeology: “The analytical methods used in archaeology to date always looked at DNA or fats – yet these are often totally useless, especially when it comes to very old organic samples. Proteins have been ignored so far because it was always believed that they would be completely decomposed, that they’re difficult to handle and that the results might be contaminated with proteins from the ambient environment. So our method opens up brand new possibilities for the analysis of organic residues on archaeological finds,” says Anna Shevchenko.
Unlike fats, proteins carry a great deal of information inside them in molecular form: for instance, the arrangement of amino acids, the building blocks of the proteins, can also contain signs of the processes used, like fermentation. As such, proteomics could develop into an interesting and suitable method in archaeometry.
The discovery has been published in the Journal of Archaeological Science.
Source: Max Planck Society [March 11, 2014]