22-2018-115, 4, p. 769-790 - Cherel A.-F., Le Gall V., Garnier N., Allard L. (2018) – Aliments et modes de conservation au Bronze moyen-final : l'habitat de Pen Mane à Guidel (Morbihan, Bretagne). Approches archéologiques et biochimiques

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22-2018-115, 4, p. 769-790 - Cherel A.-F., Le Gall V., Garnier N., Allard L. (2018) – Aliments et modes de conservation au Bronze moyen-final : l'habitat de Pen Mane à Guidel (Morbihan, Bretagne). Approches archéologiques et biochimiques

Résumé : L’originalité de l’habitat de la fin du Bronze moyen et du Bronze final de Pen Mane à Guidel dans le Morbihan, tient à la succession de plusieurs bâtiments révélant des architectures inédites. Différentes structures de stockage et deux jarres de stockage permettent d’aborder la question des modes de conservation des aliments sur le site. Les trois édifices principaux, deux bâtiments d’habitation et une construction annexe, sont associés à un petit grenier et à deux probables fosses-silos. Pour la première fois en Bretagne, deux jarres de stockage complètes de l’âge du Bronze furent découvertes en position primaire dans les fosses centrales du bâtiment d’habitation no 2 et de la construction annexe. De manière inédite en Bretagne pour cette époque, leur contenu originel a pu être identifié. En effet, des analyses biochimiques des imprégnations organiques des parois internes de ces deux conteneurs ont été réalisées par le laboratoire Nicolas-Garnier (LNG). Contre toute attente, en raison de l’acidité du sous-sol du Massif armoricain, les marqueurs organiques sont très bien conservés. Les résultats des deux extractions réalisées pour chacun des vases révèlent qu’ils ont contenu des produits laitiers et des dérivés de fruits, notamment le raisin noir mais aussi d’autres fruits, riches en acide malique. Les marqueurs de la fermentation alcoolique sont présents dans l’un des récipients. Plusieurs hypothèses concernant leur nature sont proposées ; celle d’usages successifs est privilégiée. Les comparaisons montrent que ces céramiques grossières sont pleinement adaptées à la conservation des denrées périssables. Leur déposition dans une fosse, outre leur stabilisation, permettait de maintenir une température relativement fraîche et constante nécessaire à leur conservation. Cette fonction sera probablement assurée à la fin du premier âge du Fer par les premières caves, puis les souterrains. Les différents moyens de conservation rencontrés à Guidel semblent pleinement adaptés aux divers produits à conserver.

Mots-clés : âge du Bronze final, Bretagne, structures de stockage, jarres de stockage, analyses organiques de résidus, produits laitiers, boissons (fruits sauvages, raisin noir).

 

Abstract: The importance of the Middle and Final Bronze Age settlement at Pen Mane, Guidel, in South Brittany (Morbihan) is due to the succession of several unique buildings occupied during the long use of the site. Several storage structures have been found, together with two storage vessels which enable us to examine methods of food preservation.

Two successive residential buildings have been studied on this site. Associated with these is a third contemporaneous, but smaller, structure which was possibly a kitchen annexe for culinary activities. Grinding tools (a millstone and a grinder), and most of the site’s pottery come from this area. The pottery included a storage vessel found in situ.

Radiocarbon dates indicate that the dwellings were consecutively occupied and were associated with a small granary and two possible storage pits. This is the first time in Brittany that two complete Late Bronze Age storage vessels have been found in a well-preserved condition in their original contexts (i.e. the central pit in the main building Number 2, and the annex).

It was therefore decided to analyse the organic compounds absorbed by the pottery. Chemical analyses, gas chromatography (GC) and GC-mass spectrometry (GC-MS) have been conducted on the sample by the director of the LNG Lab. Despite the acidity of the soil of the Armorican peninsula, these organic remains are very well-preserved. Results on both vessels indicate traces of milk or dairy products and wild fruits rich in malic acid, including black grape. This seems to indicate that the fruits belong to the Rosaceae family, more particularly Pomoidees. In the storage vessel from building number 2 the traces of wild fruits, including black grape, have indicated an alcoholic fermentation. This natural fermentation of the juice produced a primitive wine which would have turned to vinegar after several weeks. In the other vessel the sample contained few traces of fruits. Nevertheless, the absence of specific markers of fermentation does not necessarily indicate the absence of a fermented beverage. Certain wines or vinegars contain so little alcohol (2–3 degrees) that there may be no trace remaining. This is the first time in Brittany that organic analysis has shown the presence of a fermented drink made from wild fruits in the Late Bronze Age. The characteristic markers of each wild fruit do not exist at this date according to some studies of phytochemistry concerning all the varieties of the fruits able to produce alcoholic beverages in the temperate parts of Europe before the roman Conquest.

More recently, biochemical analysis of the contents of two Early Bronze Age vessels found by Inrap’s archaeologists (a jar in a pit in North Brittany, Côtes d’Armor, and an ornamental pot deposited in a burial in South Brittany, Morbihan), have shown alcoholic black grape beverage. Pollen grain analyses have shown the presence of the grape in Brittany in the Bronze Age. Radiocarbon dating and the style of the pottery indicate a date at the end of the third millennium (the beginning of the Bronze Age) for the Plelo (Côtes d’Armor) storage vessel, while the small Le Bono (Morbihan) pot dates from the end of the Early Bronze Age.

Both the Guidel vessels also contained milk or a dairy product, chemistry in archaeology cannot differentiate between milk, cream, butter or cheese. Milk or fresh cream put in a jar and stored in a pit could be kept for a certain time, but if made into butter the product could be stored longer for winter use. The theory of successive uses (dairy products and fermented fruit juice) fits in with the necessity of preserving seasonal products in storage vessels for lengthy periods. Comparisons show that coarse and porous pottery is completely suited to the preservation of perishable foodstuffs. Their deposition in a pit means a constant cool temperature can be maintained to aid the preservation of perishable foodstuffs.

This fermentation method is found in the first cellars, at the end of the first Iron Age, and after in the souterrains of the second Iron Age.

The various methods of preservation found in the settlement at Guidel seem completely adapted to the varied products to be stored.

Raised granaries are used to store food requiring a well-ventilated area over a long period (several months). The storage pits may also preserve food over a lengthy period, requiring in this case, a controlled level of humidity. Finally, the successful storage of the contents of the vessels in the Guidel example seem to depend on the low and constant temperature needed for dairy products or drink based on fermented fruit. Their position in the centre of the buildings suggests a frequent, or even daily, consumption of the foods stored there.

 

Keywords: Late Bronze Age, south Brittany, storage structures and vessels, organic residue analysis, dairy products, beverages (wild fruits, black grape).