Portail Hal-l'Institut Agro Rennes-Angers
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Qu'est-ce qu'un paysagiste-concepteur ? Ce que disent huit "landscape architects" de leur travail.
No full textInternational audienc
Exploring the dairy fouling process in miniaturized falling film Evaporators by microfluidics
No full textInternational audienceFouling remains an unsolved challenge in the dairy industry, affecting operational efficiency and product quality. While extensive research has focused on fouling dynamics in heat exchangers, falling-film evaporators (FFE) have received less attention. There is scientific consensus that heat-induced protein denaturation is the main reason for fouling development, neglecting other potential mechanisms especially at relatively low temperatures.In a recent study [1], we demonstrated that increasing shear rates foster the formation of whey protein depos-its and enhance their structural complexity even at temperatures below the denaturation one. While highlight-ing the role of shear rate, this work does not shed light on the surface and bulk mechanisms leading to depos-it formation. In this context, we characterized in real-time the stages of dairy fouling development using microfluidic devic-es simulating FFE conditions. We aimed at discriminating the effects of shear (0-200 s-1) and temperature (50-75 °C) on the kinetics of deposit growth during the flow of whey protein solutions (10 wt. %). The key findings of this analysis can be summarized in two points:1.At low (50 °C) and high temperatures (75 °C), no deposit formation and fast channel clogging are ob-served, respectively, thus underlining the strong influence of heat-induced protein denaturation.2.At intermediate temperatures (65 °C), shear is a limiting factor controlling the accumulation of solids at the surface.These results provide a new insight on fouling mechanisms at the micron-scale and underline the coupled effect of shear and temperature under the typical FFE operational range of temperatures
Miniaturization of the fouling of whey proteins of Falling Film Evaporator by microfluidics
No full textInternational audienceFouling is a costly open question affecting the efficiency of unit operations and the quality of the products in dairy industry. The physico-chemical reasons leading to the accumulation of proteins and minerals on stainless-steel surfaces remain currently unclear. Little of the worksin the literature focused on the fouling dynamics in heat exchangers, leading to predictive models of fouling mechanisms based on the off-line analysis of solid deposits. Conversely, fouling has rarely been investigated in falling-film evaporators despite their systematic use in dairy industry (e.g., infant formula production). Up to now, fouling has been linked to heat-induced denaturation of the whey proteins. Other possible factors have been neglected despite deposit formation has been also observed at relatively low temperatures.In a recently published work [1], we have shown that shear stress has a significant impact on the formation of surficial deposits of whey proteins using a rheofluidic method. In particular, working at temperatures lower than the whey protein denaturation one (Td ≈ 70°C), we found that increasing shear rates (0-200 s-1) favored the increase of surficial deposits and the complexification of their structure, depending on protein concentration in the solutions.Following this study, we achieved an on-line observation of whey protein deposit formation using microfluidic devices mimicking the flow (100 s-1) and environmental conditions of falling-film evaporators (50-70 °C). We aimed at discriminating the role of shear and temperature on the kinetics of deposit growth during the flow of whey protein solutions with different concentrations (10-15 wt. %). Our observations revealed the simultaneous development of whey protein aggregates in the flowing solution and surficial deposits. Our results highlighted the impact of the difference of temperature between the solution and the microdevice on the development of the deposits rather than the residence time in the channels. A quantitative analysis of the evolution of protein aggregates in solution and of the kinetics of deposit surface occupation has been performed as a function of time and position in the channel
Product innovation and export strategy
No full textInternational audienceThis paper analyses the relationship between innovation and export performance. More specifically, we highlight the effect of the introduction of new products on the quality and prices charged by firms in international markets. Based on Hallak and Sivadasan (2013)’s theoretical work, we develop a model to explain the mechanism underlying the relationship between innovation and product quality. Using a unique database of new product launches combined with data on production and trade in the French dairy industry, we tested this mechanism in several ways. Our results show that the export prices charged by the firms increase after the introduction of a new product in a given market. We also show that the projected quality of the new product increases after its introduction in a given market. This confirms the quality-upgrading effect of innovation at product level. These results are highly robust econometrically
Politique Agricole et développement rural : quelle contribution du programme LEADER ?
No full textInternational audienceL'analyse des politiques agricoles conduit spontanément à identifier les fondements sectoriels des soutiens pour le maintien et le développement des activités agricoles dans un objectif de production de denrées alimentaires. Plusieurs chapitres du présent manuel se sont ainsi attachés à décrypter les ressorts et mécanismes du fonctionnement des marchés, de la formation des revenus ou encore des régulations des filières.Toutefois d'autres analystes, qu'ils soient économistes, politistes ou sociologues, proposent de décentrer le regard, de faire un pas de côté et de mettre la focale sur une composante plus méconnue des politiques agricoles, à savoir sa dimension territoriale. Cette démarche passe par le renouvellement des cadres de lecture (i) soit en analysant de nouvelles formes de régulation économique (Allaire, 2002 ; Laurent et Du Tertre, 2008) ou de leviers d'intervention dans une perspective du décloisonnement des cadres sectoriels (Trouvé et al, 2007), (ii) soit en identifiant d'autres fonctions que la seule fonction productive de l'agriculture (</div
Modelling the distribution of rare and data-poor diadromous fish at sea for protected area management
No full textABSTRACT Anthropogenic pressures have resulted in declines in diadromous fish. Many diadromous fish which were commercially important are now threatened and protected. Little is known about their marine life history phases, and no observation-based Species Distribution Model exists for this group of species at sea. Yet, fisheries dependent and independent data could provide new insights into the distribution of diadromous fish at sea. We collated a database of 168 904 hauls from fisheries observer bycatch data and scientific fisheries surveys, from eastern Atlantic and Mediterranean waters. The distribution of eleven rare and data-poor diadromous fish (shads, lampreys, salmonids, the European eel, the thinlip mullet, smelt and the European flounder) were modelled. A Bayesian site occupancy model, that incorporates imperfect detection to account for repeat detections and non-detections, the non-random nature of fishing gear type and spatial autocorrelation was used. From the model outputs, we explored bycatch risk and the role of MPAs, required under the Marine Strategy Framework Directive and Habitat Directive and assessed. Diadromous fish were observed within relatively shallow coastal areas. Species specific gear bycatch trends were observed. Core distribution areas corresponded to their known water basin presence, indicating connectivity with their freshwater habitats. Numerous Habitat Directive Marine Protected Areas were found to be of relevance. Given the coastal distribution of these species, they are exposed to higher anthropogenic pressures from both terrestrial and marine environments. Risk of bycatch at sea for most species appears to be low. Nonetheless, for threatened individuals, even a small amount of bycatch may impact their populations, especially since misreporting is likely to be high. Differences in catchability between gears highlight potential benefits of limiting access of certain gears within protected areas to reduce bycatch
Energy restriction cancels the effect of temperature on the growth of common soles (Solea solea) in the Gironde estuary
No full textInternational audienceEstuarine and coastal ecosystems are key nursery habitats for the development and growth of many juveniles of marine fish species. Human-induced environmental changes, to which coastal and estuarine areas are particularly sensitive, will largely impact juveniles’ life history traits and consequently, the whole population at sea. Increase of water temperature is the best described and predicted environmental change related to climate change, and will certainly affect the nursery function of estuarine areas. Yet, our capacity to estimate consequences are limited and lack mechanistic models applied at the population level. As a major estuary of Western Europe, the Gironde estuary is a relevant case study to evaluate the effects of rising temperature on fish populations.To study the specific impact of temperature on life history traits of juvenile common soles (Solea solea) in the Gironde estuary, we used a bioenergetic model based on DEB theory. Since the estuary is supposed to have reached its maximum carrying capacity, effects were also estimated in a context of limited energy availability, with forecast scenario based on IPCC previsions.As soles in the Gironde estuary are below their thermal optimum, growth and development are expected to accelerate with increased temperature when food is not a limiting factor. Consequently, soles reach maturity sooner and grow larger. However, when we consider a restriction in available energy, linked to limited carrying capacity of the estuary, the effect of temperature is cancelled and changes in life history traits are negligible. However, a reduced energy in the reserve is estimated, which might alter the response to other environmental changes
Experimental study of microclimate benefits following de-sealing and revegetation in a parking lot.
No full textInternational audienceThis study investigates the evolution of microclimatic benefits following de-sealing of a 64 m² patch (Oasis) inside a parking lot located in the suburbs of Angers, France. Vegetation (trees and herbaceous species) was introduced. We compared the microclimate in the Oasis with that of a neighboring asphalt area (negative control), a meadow area (positive control), and under a tree in a sealed area (Figure 1). This comparison was conducted using on-site meteorological stations. Over the two years following de-sealing, microclimate variables were monitored, and thermal comfort was evaluated using the Universal Thermal Climate Index (UTCI) as vegetation developed. The Oasis experienced a significant reduction in surface temperature compared to surrounding asphalted areas, with a maximum decrease of 18.4°C during the first summer and 23.0°C during the second one. This cooling effect was attributed to the development of the herbaceous layer, which covered 60% of the Oasis three months after sowing and exceeded 90% coverage from the second year. The reduction in surface temperature contributed to improved daytime thermal comfort. Tree shading further enhanced local cooling, reducing UTCI by up to 8°C in shaded areas. No evidence of lower nocturnal air temperature compared to sealed reference areas was observed, possibly due to the patch's small size and air mixing with the surroundings. This study highlights that small-scale de-sealing and revegetation initiatives can deliver notable microclimate benefits in urban environments from the first year, with even greater impacts as vegetation matures, supporting urban adaptation to climate change
Peptidomic profile of human milk as influenced by fortification with different protein sources: An in vitro dynamic digestion simulation
No full textInternational audienceFortification of human milk (HM) is often necessary to meet the nutritional requirements of preterm infants. The present experiment aimed to establish whether the supplementation of HM with either an experimental donkey milk-derived fortifier containing whole donkey milk proteins, or with a commercial bovine milk-derived fortifier containing hydrolyzed bovine whey proteins, affects peptide release differently during digestion. The experiment was conducted using an in vitro dynamic system designed to simulate the preterm infant's digestion followed by digesta analysis by means of LC-MS-MS. The different fortifiers did not appear to influence the cumulative intensity of HM peptides. Fortification had a differential impact on the release of either donkey or bovine bioactive peptides. Donkey milk peptides showed antioxidant/ACE inhibitory activities, while bovine peptides showed opioid, dipeptil-and propyl endo-peptidase inhibitory and antimicrobial activity. A slight delay in peptide release from human lactoferrin and α-lactalbumin was observed when HM was supplemented with donkey milkderived fortifier
PLIAGES : Pour La cIrcularité et l’Ancrage territorial des Elevages porcinS biologiqueS
No full textNational audienceAlthough currently fragile, the organic pig sector has opportunity for development. The PLIAGES project aims to explore a theme of research identified by the ORIGAMI consortium. Its aim is to propose and test, in contrasting areas, an approach to analyse the rôle of organic pig production in local food systems. It brings together scientist with skills in technical and social sciences. It comprises three stages. The first will define the conceptual and theoretical frameworks, the second will design and test the approach, and the third is to summarise and communicate the results.Bien qu’actuellement fragile, la filière porcine sous cahier des charges Agriculture Biologique (AB) présente des atouts pour son développement. Ce parcours avec projet exploratoire propose d’approfondir des axes de recherche identifiés par le consortium ORIGAMI. Il a pour objectifs de mettre en place et de tester sur des territoires contrastés, une démarche d’analyse de la place du porc AB dans les systèmes alimentaires territorialisés, en intégrant les deux niveaux que sont la ferme et le territoire. Il regroupe des chercheurs et enseignants-chercheurs ayant des compétences en sciences techniques et sciences humaines et sociales. Il comprend trois étapes. Une étape de définition des cadres conceptuels et théoriques qui permettra la construction de l’interdisciplinarité, une étape de conception et de test de la démarche impliquant l’encadrement de stages de master 2 en réseaux et une étape de synthèse et valorisation des résultats. La démarche fera l’objet de communication auprès d’étudiants, d’acteurs des filières AB et non AB, de décideurs et de scientifiques. Les perspectives sont la construction d’un projet de recherche-action