A novel analytical technique for the characterization of ancient wine biomarkers in archaeological pottery
This study introduces a novel LC–MS/MS method utilizing specific pyranoanthocyanin biomarkers (vitisin A and B) to unambiguously identify and distinguish fermented red wine residues in ancient archaeological pottery, overcoming the limitations of conventional markers.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
For thousands of years, people have stored wine in clay jars, leaving behind faint traces of the liquid that once filled them. Archaeologists have long sought to identify these ancient residues to understand how early societies cultivated grapes, traded goods, and celebrated together. However, proving that a shard of pottery once held wine is notoriously difficult. The chemicals that signal fermentation often break down over centuries, and the molecules scientists have traditionally looked for, such as tartaric acid, are found in many fruits and plants, not just grapes. This lack of specificity means that finding these common acids does not guarantee the presence of wine; it could just as easily be a fermented fruit juice or a resin from a tree. To solve this puzzle, researchers needed a chemical fingerprint that appears only when grapes are turned into wine through the specific process of fermentation, a marker that survives the ravages of time and cannot be confused with other natural substances.
A team of scientists has now developed a new method to find exactly that kind of marker. They focused on a group of complex molecules called pyranoanthocyanins, specifically two types known as vitisin A and vitisin B. These compounds are created only when yeast, the microorganism responsible for fermentation, interacts with grape pigments and other byproducts of the brewing process. Unlike the common acids found in many fruits, these molecules do not exist in unfermented fruit or in the environment; they are born from the act of making wine. The researchers created a highly sensitive testing system capable of spotting these specific molecules even when they are present in tiny, degraded amounts inside ancient pottery. By synthesizing pure versions of these molecules in the lab to use as a reference, they built a reliable framework to distinguish true wine residues from other organic matter.
The team first tested their method on modern wines to ensure it worked correctly. They analyzed both red and white wines, finding that the target molecules appeared exclusively in the red wines, confirming that the method could differentiate between wine types. They also checked to see if these molecules could survive being absorbed into clay. They took modern ceramic powder, spiked it with red wine, and ran it through their extraction process. The test showed that the method could recover more than 80 percent of the target molecules from the clay, proving that even if the wine had soaked into the pot, the chemical signature would remain detectable. This validation step was crucial, as it demonstrated that the technique could handle the messy reality of archaeological samples where the residue is trapped deep within the ceramic matrix.
With the method proven on modern materials, the researchers turned their attention to seventy ancient ceramic samples from different parts of the world. These included jars from the Roman Imperial period found in Portugal and containers from the Sassanian and early Islamic periods discovered in Oman. When they analyzed the extracts from these ancient shards, they found clear evidence of vitisin A in several samples. In one jar from Oman, they even detected vitisin B alongside the primary marker. The presence of these specific fermentation-derived pigments provided strong, unambiguous evidence that these vessels once held fermented red grape wine. The results were not just a guess; the chemical signals matched the synthetic standards perfectly in both timing and structure, ruling out the possibility that the findings were caused by contamination or the presence of other fruit products.
This discovery offers a significant leap forward in the study of ancient food and drink. By moving beyond general markers that could belong to many sources, this new approach allows scientists to confirm the presence of grape fermentation with a high degree of confidence. The ability to distinguish between red and white wine residues also opens new doors for understanding ancient trade and consumption habits, suggesting that people in the past may have had distinct preferences or uses for different types of wine. While the study confirms that these specific molecules can survive for millennia in pottery, the researchers note that further work is needed to understand exactly how these compounds degrade over time in burial conditions. Nevertheless, the successful identification of vitisin A and B in Roman and Sassanian jars provides a powerful new tool for archaeologists, turning vague chemical hints into definitive proof of ancient winemaking.
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