The world’s oldest cheese, dating back 3,600 years, has been discovered in an unlikely place.
After analysing ancient cheese found alongside mummies in China dating from the Bronze Age, scientists have discovered the cheese is kefir.
The research, published in the journal Cell, suggests a new origin for kefir cheese – and sheds light on the evolution of probiotic bacteria.
Corresponding author Professor Qiaomei Fu, of the Chinese Academy of Sciences, said: ‘This is the oldest known cheese sample ever discovered in the world.
‘Food items like cheese are extremely difficult to preserve over thousands of years, making this a rare and valuable opportunity.
‘Studying the ancient cheese in great detail can help us better understand our ancestors’ diet and culture.’
Archaeologists discovered mysterious white substances smeared on the heads and necks of several mummies found in the Xiaohe cemetery in China’s Tarim Basin around 20 years ago.
The mummies dated back to about 3,300 to 3,600 years ago.
At the time of the discovery, researchers thought the substances might be a type of fermented dairy product, but they couldn’t identify exactly what kind.
Now, after more than a decade of advancements in ancient DNA analysis, a team led by Prof. Fu has unravelled the mystery.
The Chinese research team successfully extracted mitochondrial DNA from samples found in three different tombs at the cemetery.
They identified cow and goat DNA in the cheese samples.
Prof. Fu said the ancient Xiaohe people used different types of animal milk in separated batches, a practice differing from the mixing of milk types common in Middle Eastern and Greek cheesemaking.
The researchers also managed to recover the DNA of microorganisms from the dairy samples – and confirmed that the white substances were in fact kefir cheese.
They found that the samples contained bacterial and fungal species, including Lactobacillus kefiranofaciens and Pichia kudriavzevii, both commonly found in present-day kefir grains.
Kefir grains contain multiple species of probiotic bacteria and yeast, which ferment milk into kefir cheese, much like a sourdough starter.
Being able to sequence the bacterial genes in the ancient kefir cheese gave the researchers the chance to track how probiotic bacteria evolved over the past 3,600 years.
They compared the ancient Lactobacillus kefiranofaciens from the ancient kefir cheese with the modern-day species.
Prof. Fu explained that, today, there are two major groups of the Lactobacillus bacteria – one originating in Russia and another from Tibet.
The Russian type is the most widely used globally, including in Europe, the United States and Japan, for making yoghurt and cheese.
Prof. Fu said: ‘This is an unprecedented study, allowing us to observe how a bacterium evolved over the past 3,000 years.
‘Moreover, by examining dairy products, we’ve gained a clearer picture of ancient human life and their interactions with the world.’
‘This is just the beginning, and with this technology, we hope to explore other previously unknown artefacts.’
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