According to jars recovered from the ocean near San Felice Circeo, local grapes and imported tar pitches may have been the norms for winemakers along the Roman coast of Italy.
Researchers recovered three different wine jars, or amphorae, and examined them, giving them a valuable insight into how to make wine in this particular region in the 12th century BCE, during the late Greco-Italic period.
What makes the study so special is that it combines some of the most recent chemical analysis techniques with other techniques used in archaeobotany to discover more about these jars than would otherwise be possible.
"T]hree marine amphorae, recovered in 2018 from San Felice Circeo (Italy), provided a unique opportunity to conduct interdisciplinary research through archaeobotanical and chemical studies," according to the authors in a published paper.
One of the lab methods used in this case was a combination of gas chromatography and mass spectrometry, which are different approaches of separating and identifying chemical markers in a material in this case, trained on the organic residue left in the jars.
The researchers also looked for pollen trapped in the residue. This type of analysis has been done before, but not often on wine jars like these, and rarely for the purpose of exploring a larger historical context for a thing.
A careful examination of grapevine pollen revealed that the jars were used to make both red and white wine, and that local plants were used, although it's unclear whether or not these plants were domesticated at the time.
Nonetheless, traces of pine suggest that it was used to waterproof the jars and perhaps also to flavor the wine. The tar pitch that included the pine would have been drawn from outside the region, perhaps from Calabria or Sicily, according to researchers.
Some of the pollen grains used in the research. (Chassouant et al., PLOS One, 2022)
The presence of both pollen and charcoal allowed for a more comprehensive understanding of the pitch's origin, which is impossible to obtain through organic residue analyses alone.
A variety of other ceramics and artifacts have been discovered around the San Felice Circeo harbor, some 90 kilometers (56 miles) southeast of Rome. According to archaeologists, the area may have been close to a Roman canal.
Because of the wide range of interdisciplinar methods used in figuring out the chemical makeup of what's left in these jars, the researchers are able to go further.
It involves combining chemical and botanical knowledge with other historical and archaeological evidence, and previous investigations into wine jars such as these going beyond chemical analysis to discover the purpose of the objects.
"We have pushed the conclusion further in the understanding of ancient practices by using different approaches," say the researchers.
The study has been published in the journal PLOS One.