Wrapping and unwrapping, concepts and approaches

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Conserving Millet with Potash : Towards a Dogon Epistemology of Materials

In a climatically challenging environment, over time, the Dogon in Mali (West Africa) have developed technical strategies to cope with the scarcity of food resources and conserve millet, their subsistence crop. Millet stalk ash and potash, produced by leaching and heating ashes, are commonly used for conserving millet in granaries as well as cooked foods. In light of the anthropology of techniques, and by using operational sequences as a core methodology for field data collection and analysis, this paper explores the traditional conservation techniques used by Dogon men and women in the village of Kani Komolé, located in the Tengu kan linguistic area. This approach focuses on the material aspect of this technical system of conservation: preservation and transformation are considered as a set of material practices involving generative materials such as millet potash, which is produced out of millet ashes obtained from the combustion of millet straws and shaft. Potash is considered both as a property of ashes and as the material that results from their transformation. Through an examination of processes used for the transformation of millet – including the use of fire – this collection of operational sequences highlights implicit forms of meaning such as belief systems about materials, the ritualization of tasks and symbolic aspects of the conservation techniques, which all form part of the Dogon definition and practice of conservation. In this perspective, this paper documents the Dogon’s conservation system, based on the social aspects of millet consumption and on the cereal’s temporality. In addition, this system stems from a Dogon epistemology of materials, based on the Dogon’s understanding of the material efficacy of millet potash – that is, this substance’s inherent power as a set of active properties with relation to healing, enhancing, neutralizing spells and preserving. In this perspective, by considering millet’s material relations within the broader daily social environment of the Dogon, this paper examines both what happens when Dogon men and women prepare food for the purpose of conservation, make it ‘preservable’, and the effect of potash on foodstuffs and on the people who consume them.Vivant dans un environnement climatique contraignant, les dogons du Mali ont développé au court du temps des stratégies techniques afin de pallier au manque de resources alimentaires et de conserver leur céréale de subsistance qui est le petit mil. Pour ce faire, les cendres de tige de mil ainsi que la potasse qui résulte de la percolation lente de ses cendres puis de la cuisson du filtrat obtenu, sont très couramment utilisées afin de conserver cette céréale dans les greniers en terre et les préparations culinaires, particulièrement celles à base de mil. Sous l’angle de l’anthropologie des techniques et en utilisant la chaîne opératoire comme méthode principale de collecte et d’analyse des données de terrain, cet article explore les techniques de conservation traditionnelles du mil qui sont déployées par les hommes et les femmes dogons du village de Kani Kombolé situé dans la région linguistique Tengu Kan. En se concentrant sur la dimension des matériaux du système technique de conservation dogon, cette étude considère “conserver et transformer” comme des pratiques matérielles impliquant des matériaux génératifs qui sont la potasse de mil et la cendre dont elle est extraite et qui résulte de la calcination des tiges et du son de mil. Ainsi, la potasse est considérée à la fois comme une propriété de la cendre et comme la matière résultante de sa transformation. A travers une analyse des processus de transformation du mil notamment par le feu, les chaînes opératoires recueillies mettent en évidence des formes de significations implicites telles que des systèmes de croyances relatifs aux matières, la ritualisation et les aspects symboliques des techniques de conservation qui entrent dans une définition et des pratiques de conservation dogon. Sous cet angle, il sera question de comprendre les logiques de conservation portant sur l’aspect social de la consommation du mil et de sa temporalité. Il s’agira également de définir une épistémologie indigène des matériaux qui repose sur une conception dogon de l’éfficacité matérielle de la potasse, c’est-à-dire, la force intrinsèque de la potasse considérée par les dogons comme l’ensemble de ses propriétés actives qui permettent de soigner, d’assaisonner, de conjurer un sort ou encore de conserver. Par conséquent, en tenant compte des relations matérielles entre les différentes parties du mil dans un contexte social et quotidien plus large, cet article propose de voir tout ce qui se passe lorsque les hommes et les femmes dogons rendent conservable et de voir ce que la potasse fait aux matières et à ceux qui la consomment

Dans la Trajectoire des Choses

Dans la trajectoire des choses. Comparaison des approches francophones et anglophones contemporaines en anthropologie des techniques. Dans cette introduction, les auteurs exposent les approches francophones et anglophones de l’étude des techniques et suggèrent que ces deux traditions ont traité d’enjeux comparables. Ils les resituent dans l’histoire des Sciences humaines et analysent leur place dans le champ anthropologique. Ils retracent les débats et les échanges qui les ont enrichies, particulièrement dans leur dialogue avec d’autres disciplines connexes comme l’archéologie, la sociologie, l’Histoire de l’Art et la muséologie. En conclusion, les auteurs suggèrent que l’un des éléments qui  différencie ces traditions réside dans la manière dont est pensée et traitée la question du déterminisme.Within the Trajectory of Things. Perspectives on anglophones and francophones anthropological approaches of techniques and technology. In this introduction, the authors present francophones and anglophones approaches of the study of techniques and suggest that both traditions have dealt with comparable questions. They replace these approaches in the history of social sciences, and analyse their position in the field of anthropology. They summarise some of the debates and exchanges that have enrich them, in particular during the dialogues with  disciplines such as archaeology, sociology, art history and museology. As a conclusion, the authors suggest that one of the elements that help distinguishing these traditions can be found in the way in which they have tackled the question of determinism

A praxeological approach to dogon material culture

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Linseed oil presents different patterns of oxidation in real-time and accelerated aging assays

This study aimed at verifying if the hypothesis that one day at 60 °C is equivalent to one month at 20 °C could be confirmed during linseed oil aging for 6 months at 20 °C and 6 days at 60 °C using the “Schaal oven stability test”. Tests were conducted with linseed oil supplemented or not with myricetin or butyl-hydroxytoluene as antioxidants. Oxidation was evaluated with the peroxide and p-anisidine values, as well as the content in conjugated dienes and aldehydes. All four indicators of oxidation showed very different kinetic behaviors at 20 and 60 °C. The hypothesis is thus not verified for linseed oil, supplemented or not with antioxidant. In the control oil, the conjugated dienes and the peroxide value observed were respectively of 41.8 ± 0.8 Absorbance Unit (AU)/g oil and 254.3 ± 5.8 meq. O2/kg oil after 6 months at 20 °C. These values were of 18.2 ± 1.3 AU/g oil and 65.2 ± 20.3 meq. O2/kg after 6 days at 60 °C

Validation of the Analytical Procedure for the Determination of Malondialdehyde and Three Other Aldehydes in Vegetable Oil Using Liquid Chromatography Coupled to Tandem Mass Spectrometry (LC-MS/MS) and Application to Linseed Oil

Secondary oxidation products of fatty acids, mainly aldehydes, are susceptible to cause significant deterioration in chemical, sensory and nutritional food properties, as well as adverse health effects. An analytical method involving separation by liquid chromatography coupled to the detection by tandem mass spectrometry (LC-MS/MS) has been developed to evaluate the concentration of four aldehydes in oil samples: malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), 4-hydroxy-2-hexenal (4-HHE) and 2,4-decadienal (2,4-DECA). The optimisation of the extraction, derivation, detection and quantification has been finalised for coconut oil, used as a model of vegetable oils. The method has been validated according to the criteria and procedure described in international standards. The evaluated parameters include specificity/selectivity, recovery, precision, accuracy, uncertainty, limits of detection and quantification, using the concept of accuracy profiles. These parameters have been evaluated during experiments planned on different non-consecutive days with coconut oil spiked at different levels of concentration. The validation of the developed analytical method showed that it is possible to analyse MDA, 4-HHE, 4-HNE and 2,4-decadienal in oil samples, in the same run, with a very good accuracy for MDA, and a defined accuracy at specified concentrations for the three other aldehydes. The accuracy profile of MDA showed a recovery rate of 100 % (±1) and a maximum coefficient of variation for the intermediate precision of 14 % at 0.15 mg kg−1. For the three other aldehydes, recovery rates ranged between 79 and 101 % and coefficient of variation for the intermediate precision between 13 and 23 %. In first pressure linseed oil, stored for several days at 60 °C according to the Schaal oven test, it was shown that 4-HHE was the most produced aldehyde, reaching levels of 85 and 382 μmol kg−1 after 12 and 24 days, respectively, versus levels of 18 and 28 μmol MDA kg−1 of oil, respectively, and 17 and 51 μmol 4-HNE kg−1 of oil. © 2014, Springer Science+Business Media New York

Technologies

Techniques & culture, désormais imprimé sur un nouveau papier plus apte à restituer les narrations photographiques et textuelles, inaugure un travail éditorial fondé sur différentes rencontres franco-britanniques à propos des objets, des techniques et technologies, à des échelles disciplinaires, temporelles et spatiales des plus diverses. Vous y trouverez, entre autres, une réflexion sur la transmission et le plaisir au travail, une nouvelle conception du corps et du sujet, des changements dans les usages contraceptifs au Brésil…, mais aussi des terrains ethnographiques inédits, chez les amateurs de jazz, les « tatoués » de Liège ou les rasés des pelotons cyclistes…