Chemical and sensory profile of shipwreck wines

by | Oct 1, 2021 | Oenology research, Winetech Technical

We present here the chemical and (informal) sensory evaluation of some wines recovered from two shipwrecks.

 

Introduction

When it comes to grapes and wine, the diversity of the products makes the work interesting and challenging. However, maybe once in a lifetime, we might have the opportunity to evaluate something truly extraordinary. In the recent past, there have been reports of wines and beers recovered from shipwrecks1,2 submitted to chemical and sensory analyses. In 2019, the researchers from the Department of Viticulture and Oenology had the chance to collaborate with the Maritime Archaeology Unit of the Iziko South African Museums in a study unique in South Africa: analysing wines recovered from some of the shipwrecks off the coast in or near False Bay.

 

Original wine bottles recovered from HMS Colebrooke, some of them still with the original cork and wax seal.

 

Cape of Good Hope or Cape of Storms?

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 in 1778. Colebrooke, launched 1770 in Portsmouth, stopped in Madeira and wrecked on 24 August 1778 when she struck the Anvil rock entering False Bay. The ship did not sink there, but rather ran aground in Kogel Bay. The wreck was discovered in 1984 and salvaged in the 1980s and 1990s. It is difficult to know whether the wine was cargo or for private use. The wreck was exploited by treasure hunters and not archaeologically excavated; as such, very little contextual information is known. We could analyse seven samples recovered from the ship.

To expand the sample pool with more examples of old wine, we have included another sample (coded M), recovered from the wreck of the SS Maori, sunk in 1909 near Llandudno.

 

Chemical analyses

A minimal volume of wine (less than 50 mL) was analysed using untargeted analyses, elemental analysis, sugars and organic acids. The analyses were performed at the Chemical Analytical Lab of the South African Grape and Wine Research Institute, the Mass Spectrometry Unit, Nuclear Magnetic Resonance Unit, and the ICP-MS Unit of the Central Analytical Facility of Stellenbosch University.

Unexpected chemical characteristics regarding the metal concentrations, sugar and acid composition, as well as the aroma profile were found. For example, compared to current export regulations, the levels of heavy metals were considerably higher in most samples (Figure 1). Trace element analysis revealed high levels of As, Mn, Sr, Mo and Pb in all samples from the wrecks. This was not necessarily due to the wine itself, but possibly due to the composition of the glass bottle and leaching over time. X-ray diffraction could show if the source of heavy metals were the bottles. One sample (NC) showed very high levels of Ca and Na probably due to seawater entering the bottle.

 

FIGURE 1. Elemental analysis for the wine samples recovered.

 

FIGURE 2. Organic acids, sugars and alcohol composition of the samples. The missing columns indicate the compounds not detected.

 

When the bottles were brought to the museum for storage after salvaging, some of the recovered wines were transferred into new bottles, while others were left in the original ones. This could explain the differences in organic acids and sugars (storage in nonsterile environment) and alcohol levels (volatilisation?) (Figure 2).

The untargeted analyses showed various compounds including fermentation-derived products (esters, alcohols, aldehydes and fatty acids), terpenoids (linalool and fenchone) and “woody” compounds (furfural and guaiacol). The in-depth analysis of these results is still taking place.

 

Informal sensory evaluation

The evaluation was done by four experienced researchers using free description and is based only on aroma. Incredibly, some of the samples still presented wine-like features related to aroma in both the chemical and the sensory evaluation. The wines transferred into new bottles for storage have maintained these wine-like characters. The samples left in the original bottles have been exposed to the storage environment, because the corks shrunk and allowed air (and contaminants?) ingress.

The samples with the profiles presented in Figure 2 are some of the more wine-like ones. The description of the samples was generally quite a challenging exercise even for experienced researchers. The wines were very different from each other and from what we are used to smelling in a wine, even a very old one.

 

FIGURE 3. Aroma profile of some of the wine samples recovered from SS Maori (sample M, top left) and HMS Colebrooke (samples M68, top right and M64, bottom).

 

Take home message

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.

Even in the harshest and strangest conditions, some wines still survive.

 

Abstract

The Southern tip of Africa is littered with the wrecks of hundreds of ships. Gale force winds, strong ocean currents, treacherous reefs, inaccurate maps and unsophisticated navigational technology often proved too much for the navigators of the old days. The cargoes recovered with the help of marine archaeologists can offer some insight into the life and times of the travellers and crew.

 

Contributing researchers: Astrid Buica, Cody Williams, Valeria Panzeri, Jaco Boshoff and Wendy Black.

 

References

  1. Jeandet, P., Heinzmann, S.S., Roullier-Gall, C., et al., 2015. Chemical messages in 170-year-old champagne bottles from the Baltic Sea: Revealing tastes from the past. Proceedings of the National Academy of Sciences 112(19): 5893 – 5898. Doi: 10.1073/pnas.1500783112.
  2. Londesborough, J., Dresel, M., Gibson, B., et al., 2015. Analysis of beers from an 1840s shipwreck. Journal of Agricultural and Food Chemistry 63(9): 2525 – 2536. Doi: 10.1021/jf5052943.

 

– For more information, contact Astrid Buica at astrid.buica@gmail.com.

 

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