Is it possible to identify ancient wine production using biomolecular approaches?

Abstract

Chemical analysis of archaeological artefacts is used with increasing regularity to understand how wine was produced, traded, and consumed in the past and to shed light on its antiquity. Based both on an extensive review of the published literature and on new analyses, here we critically evaluate the diverse range of methodological approaches that have been used for wine identification. Overall, we conclude that currently none of the proposed chemical 'biomarkers' for wine provide unequivocal evidence. Nevertheless, valid interpretations may be offered if systematically supported by additional contextual data, such as archaeobotanical evidence. We found the extraction and detection method to be particularly crucial for successful identification. We urge the use of controls and quantification to rule out false positives. DNA sequencing offers potential for identifying wine and provides much higher taxonomic resolution, but work is needed to determine the limits of DNA survival on artefacts.

New insights into early medieval Islamic cuisine: Organic residue analysis of pottery from rural and urban Sicily

“…Comparison of the proportions of malic and tartaric acids in the pots was used to distinguish between the presence of grapevine products and that of other plants ( Fig 7 ) [ 17 , 85 – 88 ] ( S3 Text ). Four vessels from CLESP and one sample from CSP produced a ratio of tartaric acid to the sum of tartaric and malic acids (%TA) of greater than 35%, characteristic of ripe grapes and their products (wine, juice, vinegar), as well as tamarind and some pomegranate cultivars [ 17 , 85 ] ( Fig 7B ). Indeed, studies have suggested that cooking wares may have been used for the storage or heating of wine as well as being used as a flavouring for food in medieval Florence and Piombino [ 89 , 90 ].…”

“…Small organic acids, which are relatively insoluble in organic solvents were extracted from > 50% of the samples, using an acid butylation extraction developed by Garnier and Valamoti (2016) [17,29,85]. Malic and tartaric acids were identified, in variable amounts, in 97% and 70% of them, respectively.…”

“…Fumaric, maleic, malonic, and oxalic acids were detected less frequently, in 10%, 14%, 8% and 3% of the samples respectively. Although tartaric acid is one of the main acids in grapes and wine, its mere presence is not sufficient to formally identify these products in CLESP and Palermo vessels, since it also exists in other plants [17,85] and low amounts may be attributed to contamination from the burial environment [85]. Following the recommendations suggested by Drieu et al (2020) and (2021), we performed a quantification of tartaric acid to consider only vessels with a significant amount of tartaric acid, which is unlikely to be contamination [17,85].…”

“…Although tartaric acid is one of the main acids in grapes and wine, its mere presence is not sufficient to formally identify these products in CLESP and Palermo vessels, since it also exists in other plants [17,85] and low amounts may be attributed to contamination from the burial environment [85]. Following the recommendations suggested by Drieu et al (2020) and (2021), we performed a quantification of tartaric acid to consider only vessels with a significant amount of tartaric acid, which is unlikely to be contamination [17,85]. Comparison of the proportions of malic and tartaric acids in the pots was used to distinguish between the presence of grapevine products and that of other plants (Fig 7) [17,[85][86][87][88] (S3 Text).…”

“…Following the recommendations suggested by Drieu et al (2020) and (2021), we performed a quantification of tartaric acid to consider only vessels with a significant amount of tartaric acid, which is unlikely to be contamination [17,85]. Comparison of the proportions of malic and tartaric acids in the pots was used to distinguish between the presence of grapevine products and that of other plants (Fig 7) [17,[85][86][87][88] (S3 Text). Four vessels from CLESP and one sample from CSP produced a ratio of tartaric acid to the sum of tartaric and malic acids (%TA) of greater than 35%, characteristic of ripe grapes and their products (wine, juice, vinegar), as well as tamarind and some pomegranate cultivars [17,85] (Fig 7B ).…”