Cody Williams1, Jaco Boshoff2, Wendy Black3, Valeria Panzeri1, Astrid Buica1
1 South African Grape and Wine Research Institute, Department of Viticulture and Oenology, Stellenbosch University, South Africa
2 Iziko Museums of South Africa, Maritime Archaeology Unit, Research and Exhibitions, Cape Town, South Africa
3 Iziko Museums of South Africa, Archaeology Unit, Research and Exhibitions, Cape Town, South Africa
Email contact: abuica[@]sun.ac.za
AIM: The Cape of Storms (also known as Cape of Good Hope) is renowned for harbouring a multitude of shipwrecks due to the inherent treacherous coastline and blistering storms. One such shipwreck is the English East Indiaman Colebrooke, wrecked in False Bay, South Africa, in 1778. A discovery on the shipwreck was a shipment of wine of unknown origin and style, possibly Madeira as it was known that the English East India Company often purchased wine from there but this was not mentioned in the ship’s log. As the wreck was exploited by treasure hunters, very little contextual information is known. To further expand the sample pool with more examples of old wine, we have included another sample recovered from the wreck of the SS Maori sunk in 1909. Additionally, three samples of (old) wines stored in vinotheque conditions were included: a Château d’Yquem (1918 vintage) and two Château Margaux (1984).
METHODS: A minimal volume of wine (<50 mL) was analysed using untargeted analyses (GC-MS, LC-HRMS and NMR spectroscopy), metals (ICP-MS/OES), and sugars and organic acids (HPLC-DAD-RID). Important volatile aroma compounds were identified by HS-SPME-GCMS and their identification confirmed using Wiley/NIST libraries and RI. A screening exercise was performed by experienced researchers to sensorially evaluate the possible wine-like aromas.
RESULTS: Unexpected chemical characteristics regarding the metal concentrations, sugar and acid composition as well as the aroma profile were found. Compared to current export regulations, the levels of heavy metals were considerably higher, possibly due to the bottle glass composition and leaching over time. The untargeted analyses showed various compounds including fermentation-derived products (esters, alcohols, aldehydes and fatty acids), terpenoids (linalool, fenchone) and “woody” compounds (furfural and guaiacol). Incredibly, some of the samples still presented wine-like features related to aroma both in the chemical and the sensory evaluation.
CONCLUSIONS: Unlike other work where the source and/or type of beverage recovered from shipwrecks were known, and with a limited volume of sample, we could still obtain results providing interesting “chemical snapshots” of old wines using advanced analytical and spectroscopic techniques. Combining new technology platforms in analytical chemistry can provide valuable insight into the composition of wines recovered from shipwrecks with the help of maritime archaeologists. Including analyses such as X-ray diffraction on the bottles can assist in tracing more information about the sources of heavy metal content and possibly even the origin of the wines.
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