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Proteomics

Original deli delights discovered

by Tien Nguyen
August 22, 2018 | APPEARED IN VOLUME 96, ISSUE 34

 

09634-newscripts-fireplaceCXD.jpg
Credit: Alexis Pantos
Stale flatbread: Bread was baked in this fireplace 4,000 years before agriculture emerged.

Oldest cheese uncovered

Archaeologists at Cairo University were sweeping sand from the wall of an Egyptian tomb when they saw the broken jars. Their contents may have appeared paltry to the casual observer—an off-white mass solidified inside a faded canvas fabric—but the expert excavators quickly realized their luck. They had stumbled upon a rare find: a still-intact chunk of ancient cheese.

The tomb, and presumably the cheese, belonged to Ptahmes, a high-ranking official under Pharaohs Sethi I and Ramses II, who lived about 3,200 years ago, making the mass the oldest solid cheese ever discovered (Anal. Chem. 2018, DOI: 10.1021/acs.analchem.8b02535).

To confirm its hunch, the team whisked the sample, about 10 g of it, off to a lab, where it ended up in the hands of 29-year-old analytical chemist Enrico Greco of the University of Catania. Greco is no stranger to dealing with delectable ancient artifacts, as he and his colleagues analyzed the oldest Italian olive oil and second-oldest wine earlier this year.

The biggest challenge with the cheese, Greco tells Newscripts, was the fact that centuries of exposure in the alkaline desert had destroyed almost all the fats in the sample, which meant that Greco’s team couldn’t use its go-to detection tool, gas chromatography/mass spectrometry.

So the researchers turned to a technique typically used for modern biological samples, called proteomics, which let them identify peptide chains in the cheese and match them with the peptides of known protein sources. They found about 500 peptides, most of them belonging to humans and introduced through contamination. However, a handful came from bovine milk proteins, such as casein and serum albumin, that are giveaways of a dairy-based past.

The cheese sample also revealed a peptide from Brucella melitensis biotype I, the bacterium behind the deadly disease brucellosis, which is transmitted by drinking unpasteurized milk. While brucellosis has been discovered in mummy bones, the team’s finding is the first direct evidence connecting the disease from animals to ancient humans.

 

Bread beginnings

09634-newscripts-cheese.jpg
Credit: University of Catania/Cairo University
Aged cheese: This jar of 3,200-year-old cheese stands alone.

But before there was cheese, there was bread. Thousands of years before, in fact, according to a surprising discovery that dates the origins of bread to 14,400 years ago (Proc. Natl. Acad. Sci. USA 2018, DOI: 10.1073/pnas.1801071115).

The University of Copenhagen’s Amaia Arranz-Otaegui was part of the team who found the ancient flatbread’s charred remains in northeastern Jordan in a fireplace belonging to Natufian hunter-gatherers. “We did not expect to find bread there,” she tells Newscripts.

Scientists have long thought that bread emerged during the Neolithic period, when people began to domesticate crops, she explains. The new findings, however, suggest that bread predates agriculture in southwest Asia by some 4,000 years.

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At first, she labeled the unrecognizable bread crumbs as processed plant remains. It wasn’t until she met study coauthor Lara Gonzalez Carretero of the University College London, who studies ancient foodstuffs, that they realized what she had.

Gonzalez Carretero analyzed the samples using scanning electron microscopy. They determined that the bread was probably made by baking a dough made from water and a flour of ground cereals and club-rush tubers. The closest version that we know of today may be unleavened Arabic naan or pita bread, Arranz-Otaegui says.

Yet the relationship between bread and agriculture remains a mystery. Some researchers suggest that foods like bread and beer may have started as luxury items and that as humans became motivated to make more of the products, organized cultivation arose. More research is needed to fully understand the rise of bread, Arranz-Otaegui says, adding that “time will tell.”

Please send comments and suggestions to newscripts@acs.org.

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