World’s oldest cheese found on 3500-year-old Chinese mummies

A mysterious white substance found on Bronze Age mummies in China has proven to be the world’s oldest cheese.

The cheese remnants were first found about two decades ago, smeared on the heads and necks of mummies found in the Xiaohe cemetery in Xinjiang province, which date from around 3500 years ago.

It has been long suspected that the substance may have had a fermented dairy origin, but only now have molecular tools become powerful enough to confirm their make-up.

Based on the presence of yeast, lactic acid bacteria and proteins from ruminant milk in the samples, Qiaomei Fu at the Chinese Academy of Sciences in Beijing and her colleagues have identified the substance as a kind of kefir cheese.

Kefir is a traditional drink made by fermenting milk using kefir grains, which are pellets of microbial cultures, like a sourdough starter.

Fu says the substance was no longer immediately recognisable as kefir cheese. “Due to their age, these pale-yellow cheese samples smelled of nothing and were powdery to touch and a little crumbly,” she says.

While there has been archaeological evidence from pottery of cheese-making technology from as long as 7000 years ago, no one has ever discovered such ancient cheese.

The team found goat and cow DNA in the samples, but it appears that the milk from each of these animals was kept separate – unlike the mixed cheeses in many Greek and Middle Eastern cheese-making traditions. This may have been because goat milk is lower in lactose and so less likely to cause gut problems when consumed.

Fu and her colleagues also recovered the DNA of Lactobacillus kefiranofaciens bacteria from the dairy samples, which they compared with the genomes of modern strains used to make kefir.

The modern strains have evolved in line with the preferences of cheese consumers, says Fu. For example, the DNA analysis suggests the new strains have been selected to cause less of an immune response in the human intestine.