Agriculture, alimentation et environnement

International audienceLa modification des milieux par l'être humain n'est pas chose nouvelle-elle remonte au néolithique, avec l'apparition de l'agriculture-mais prend un tour nouveau à partir du XX e siècle avec la spécialisation de celle-ci et le recours massif à des intrants extérieurs, d'où des effets nocifs. Thierry Doré et Gilles Trystram montrent que, si la transition écologique est nécessaire, il faut se garder de toute solution systématique. Les impacts d'un mode d'agriculture doivent être vérifiés sur une large gamme de critères : ce qui est bénéfique sur un plan peut ne pas l'être sur un autre. Il faut en outre chercher à réaliser les meilleurs compromis possibles entre les divers services écosystémiques rendus par l'agriculture. Quant aux effets plus spécifiques de l'alimentation sur l'environnement, ils sont aussi nombreux, compte tenu d'un système agro-industriel dominant. Celui-ci doit par ailleurs s'adapter à la diversité des agricultures, tout en continuant de garantir l'accès aux aliments et leur sécurité sanitaire, de répondre aux diverses attentes des consommateurs et de satisfaire les exigences écologiques

Поглощение воды и водных растворов глинополимерными нанокомпозитами внедрения

Рассмотрено первичное и повторное поглощение воды и раствора, имитирующего жидкие отходы атомных станций, глинополимерными нанокомпозитами внедрения, синтезированными на основе бентонита. Показано, что частицы глинополимерного нанокомпозита более эффективно поглощают воду и солевые растворы по сравнению с частицами природного бентонита.Розглянуто первинне і повторне поглинання води і розчину, який імітує рідкі відходи атомних станцій, глинополімерними нанокомпозитами проникнення, синтезованими на основі бентоніту. Показано, що частинки глинополімерного нанокомпозита ефективніше поглинають воду і сольові розчини у порівнянні з частинками природного бентоніту.In many cases the use of nanocomposites is restrained by insufficient knowledge of their properties. It primarily relates to intercalated nanocomposites, especially the nano composites with particles size less than 0.6 mm, containing a significant amount of clay (>60 %). The research is focus on the study of the properties of such na nocomposites. The bentonite clay from the Cherkassy deposit comprising up to 95 % of Ca-montmorillonite was used for the synthesis of nanocomposites. The preliminary substitution of Na⁺ cations for Ca²⁺ and Mg²⁺ cations was carried out. The nanocomposites clay-polymer were obtained in the process of free radical polymerization. The nanocomposites, dried at 105 ºC with particle size of 0.4 ÷ 0.6 mm were used for experiments. The properties of the nanocomposites to take up water and solutions were studied by Enslin method. The maximum value of water uptake was 69.45 ml/g. Subsequently, the sample was dried on the filter to constant weight and repeated water uptake was examined. In this case, the result was 82 ml/g, i. e. in repeated contact with water particles absorbed by 18 % more amount water than during first water uptake. The increase in water uptake is due to nonuniform polymerization (in volume and time), which resulted in deformation of some polymer chains and only after water absorption, polymer chains have a chance to take a more low-energy position. Since this phenomenon was observed for particle size of less than 0.6 mm, it can be assumed that the crystallites or aggregates of intercalated nanocomposites clay-polymer are the sites of the beginning of acrylamide polymerization. The rate of water re-absorption was lower than in case of the primary water uptake up to period of time of 1000 min and was constant to 5000 min while the rate of primary absorption decreased substantially after 1000 min. The sorption capacity of nanocomposites for solutions simulating waste of nuclear power plants was 18 ml/g that was higher than absorption by natural bentonite (3.4 ml/g). Thus, the intercalated nanocomposites clay-polymer could be promising materials as components of the geochemical and water insulating barriers

8.8. Les enjeux de la durabilité : comment concilier ces nouvelles contraintes avec les exigences actuelles ?

La construction du système alimentaire des pays développés s’est faite à travers un certain nombre d’étapes historiques, plus ou moins marquées (Figure 1). La réduction de la diversité des matières premières afin de maîtriser des procédés de fabrication en termes de productivité et de régularité est sans doute le premier facteur. Cette réduction de diversité s’est accompagnée de la production d’ingrédients et d’additifs générant une industrie d’assemblage créatrice de diversité de produits fi..

Besoins des industries alimentaires : alimentation, nutrition et élaboration d’aliments

The food industries have to face new challenges and new stakes. The impact of food on nutrition and health become very important and the strategies of the companies have to change. The paper analyses the existing stakes and the way that companies have to develop in order to obtain products evolution and process reengineering. The difficulties are highlighted and the limitation of existing approaches too

Modelling of food and food processes

International audienceModelling is an important task in food engineering and numerous approaches are possible. Based on the massy experience the paper discusses the challenge, interest and difficulties of modelling of food and food processes. Some key points are specifically discussed mainly on the base of heat processing operation. Heat and mass transfer and their consequences on structure evolution and on the building of the chemical content of food are discussed. Different kind of modelling approaches are also discussed considering control, optimisation and design objective. The coming challenge is as a conclusion presented on two main questions. The building of parameters that are necessary for simulation, mainly using molecular modelling approaches and the challenges related with scales description and the way a continuous understanding becomes probably possible in the future between all the scales

Automatisation et optimisation de procédés alimentaires: vers des solutions hybrides

Automatisation et optimisation de procédés alimentaires: vers des solutions hybrides. 5. école de printemps francophone en nanotechnologies et nanosystèmes, 24-28 ma