Lopez C.,French National Institute for Agricultural Research |
Lopez C.,Agrocampus Ouest
Current Opinion in Colloid and Interface Science | Year: 2011
Milk fat globules are the natural colloidal assemblies secreted by the mammary epithelial cells to provide lipids and other bioactive molecules in the gastrointestinal tract of newborns. They are also consumed by human adults in food products such as cream and cheeses. These biological entities (about 4μm diameter) have a complex architecture composed of a core rich in triacylglycerols (TAGs) enveloped by a biological membrane, the milk fat globule membrane (MFGM). Although their utmost importance for infants and their functional and nutritional role in dairy products, milk fat globules remain the least understood aspect of milk. This paper provides an overview of recent knowledge with emphasis on milk fat globule origin, size heterogeneities, fatty acid and TAG composition. The crystallisation properties are reported. Recent studies focusing on the MFGM including characterisation of its composition, probing of its structure, and accumulation of scientific evidence of MFGM nutritional and health properties are also discussed. The unique composition and structure of milk fat globules leading to specific functionalities are highlighted. © 2011 Elsevier Ltd.
Gohin A.,Agrocampus Ouest
Renewable and Sustainable Energy Reviews | Year: 2016
The estimations of land use changes and greenhouse gas emissions induced by biofuels remain highly controversial. After some first estimates in 2009, the California Air Resource Board releases new estimates in 2014. This paper explains two striking new results. First, the absolute reduction in the estimate of average US soya biodiesel is much greater than the reduction in the estimate of average US corn ethanol (by respectively 33 and 10 g CO2 eq/MJ). According to the new estimates, these two biofuels now induce more similar greenhouse gas emissions. Second, the newly reported EU and US canola biodiesel estimates are very different (respectively greater than 35 and 10 g CO2 eq/MJ). Using the public and transparent methodologies developed by the California Air Resource Board, we find that these two striking results are mostly explained by some weak initial economic data. In both cases, the undervaluation of the initial oilmeal productions generates upward bias in the land use changes and carbon emission estimates by reducing the co-product effects. We find that the new closer estimates reported for the US soya biodiesel and corn ethanol are explained by an appropriate revision of the world production of oilmeal and the inclusion of oilmeal trade flows. We also find that the reported significant difference between the EU and US canola biodiesel estimates nearly disappears when the initial data on European land values, oilmeal production and trade values are improved. We then emphasize that any economic analysis is only as valuable as the quality of the supporting data allows. The current focus in academic and policy circles on unobserved elasticity values to assess biofuel impacts is not sufficient. © 2015 Elsevier Ltd. All rights reserved.
Kouba M.,Agrocampus Ouest |
Mourot J.,Agrocampus Ouest
Biochimie | Year: 2011
The fatty acid composition of animal products (eggs, milk and meat) is the reflect of both the tissue fatty acid biosynthesis and the fatty acid composition of ingested lipids. This relationship is stronger in monogastrics (pigs, poultry and rabbits) than in ruminants, where dietary fatty acids are hydrogenated in the rumen. There is an increasing recognition of the health benefits of polyunsaturated fatty acids (PUFA), because these fatty acids are essential for humans. In addition, the ratio n-6/n-3 fatty acids in the human diet is important. This ratio by far exceeds the recommended value of 5. Therefore, inclusion of fish meals, or n-3 PUFA rich oils, or linseed in animal diets is a valid means of meeting consumer demand for animal products that are nutritionally beneficial. The studies that are undertaken on animals mainly use diets supplemented with linseed, as a source of n-3 fatty acids. The use of linseed diets generally leads to an increased n-3 fatty acid content in animal products (egg, meat, milk) in ruminants and monogastrics. Recent studies have also demonstrated that neither the processing nor the cooking affects the PUFA content of pork meat or meat products. The ability of unsaturated fatty acids, especially those with more than two double bonds, to rapidly oxidise, is important in regulating the shelf life of animal products (rancidity and colour deterioration); however, a good way to avoid such problems is to use antioxidant products (such as vitamin E) in the diet. Some studies also show that it is not necessary to feed animals with linseed-supplemented diets for a long time to have the highest increase in PUFA content of the products. So, short-term diet manipulation can be a practical reality for industry. As the market for n-3 PUFA enriched products is today limited in most countries, other studies must be undertaken to develop this kind of production. 2009 Elsevier Masson SAS. All rights reserved.
Michel J.-C.,Agrocampus Ouest
Vadose Zone Journal | Year: 2015
Hydrophobicity of organic matter is the primary factor affecting soil physical properties such as soil structural stability after drying. In horticultural production, the measurement of wettability is even more relevant due to the large use and high content of organic materials in growing media and to the large and rapid variations in water content in the media (due to the limited volumes of pots or containers), both of which can quickly create hydrophobic conditions. This review discusses the methods used for measuring the wettability of growing media, the evolution of wettability vs. water content, ways for limiting hydrophobicity, and finally the relationships between growing media wettability and physical properties. In addition to the indirect estimation of hydrophobicity based on physical properties such as water holding capacity, contact angles obtained from capillary rise and hydration efficiency tests are the most common methods describing the changes from hydrophilicity to hydrophobicity of organic growing media in relation to water content. Wetting agents and clay have been shown to reduce the water repellency of growing media under the driest conditions. A general trend of increasing water repellency during desiccation from highly decomposed peat > bark > weakly decomposed peat > wood products > coco fiber has been documented. As for water retention, hysteresis phenomena in contact angles have been shown during drying–wetting cycles. The influence of hydrophobicity on water retention characteristics has also been modeled, providing evidence that hydrophobicity is a function of the growing medium pore size domain. The reciprocal effects of physical and biological roles of roots on the wettability and physical properties of growing media should be investigated in future research. © Soil Science Society of America.
Gaucheron F.,Agrocampus Ouest
Journal of the American College of Nutrition | Year: 2011
Milk and dairy products contain micronutrients such as minerals and vitamins, which contribute to multiple and different vital functions in the organism. The mineral fraction is composed of macroelements (Ca, Mg, Na, K, P, and Cl) and oligoelements (Fe, Cu, Zn, and Se). From a physicochemical point of view, the chemical forms, the associations with other ions or organic molecules, and the location of macroelements such as Ca, Mg, Na, K, P, and Cl in milk are relatively well described and understood. Thus, it is admitted that these macroelements are differently distributed into aqueous and micellar phases of milk, depending on their nature. K, Na, and Cl ions are essentially in the aqueous phase, whereas Ca, P, and Mg are partly bound to the casein micelles. About one third of the Ca, half of the P, and two thirds of the Mg are located in the aqueous phase of milk. Dairy products are more or less rich in these different minerals. In cheeses, mineral content depends mainly on their processing. The Ca content is strongly related to the acidification step. Moreover, if acidification is associated with the draining step, the Ca content in the cheese will be reduced. Thus, the Ca content varies in the following increasing order: milks/fermented milks/fresh cheeses, soft cheeses, semi-hard cheeses, hard cheeses. The chemical forms and associations are less described than those present in milk. Concerning Ca, the formation of insoluble calcium phosphate, carbonate, and lactate is reported in some ripened cheeses. The NaCl content in cheeses depends on the salting of the curd. From a nutritional point of view, it is largely admitted that milk and dairy products are important sources of Ca, Mg, Zn, and Se. The vitamin fraction of milk and dairy products is composed of lipophilic (A, D, E, and K) and hydrophilic (B1, B2, B3, B5, B6, B8, B9, B12, and C) vitamins. Because of their hydrophobic properties, the lipophilic vitamins are mainly in the milk fat fraction (cream, butter). The hydrophilic vitamins are in the aqueous phase of milk. For one part of these vitamins, the concentrations described in the literature are not always homogenous and sometimes not in accordance between them; these discrepancies are due to the difficulty of the sample preparation and the use of appropriate methods for their quantification. However, there is no doubt of the significant contribution of milk and dairy products to the intake of vitamins. Milk and dairy are considered essential sources for vitamins.
Ridier A.,Agrocampus Ouest
Canadian Journal of Agricultural Economics | Year: 2012
In this paper, we propose an analysis and modeling of farmers' decision to convert a part of their annual crops area into woody crops: short rotation coppices (SRCs). Different criteria-technical, economic, and financial-are highlighted in the farmers' decision to adopt this production. A farm-level model is proposed and incorporates these decision criteria. The objective is to test several incentive scenarios to encourage risk-averse cereal farmers to plant trees. A multiperiod model of investment is built and tests possible adoption by farmers based on financial and structural parameters and according to the outlook of agricultural markets. The simulations show that if the cash crop prices fluctuate in the future and if farmers are risk averse the strategy of on-farm diversification toward woody crops under contractual arrangements could be relevant for farmers to mitigate the risks in the long run. Cet article présente une analyse et une modélisation de la décision d'un agriculteur céréalier qui souhaite convertir une partie de sa surface en grande culture en Taillis à Courte Rotation (TCR). Un modèle multi-périodique d'investissement est construit et incorpore différents critères techniques, économiques et financiers qui entrent dans la décision d'adopter ces nouvelles cultures pérennes. Le modèle permet de tester le rôle de différents types de soutiens, proposés aujourd'hui dans le cadre de la Politique Agricole Commune européenne, permettant d'encourager les agriculteurs averses au risque à planter des arbres. Les simulations montrent que si les prix des grandes cultures annuelles fluctuent à l'avenir, si la plantation d'arbres est soutenue et si les agriculteurs sont averses au risque, la stratégie de se diversifier vers la plantation d'arbres à croissance rapide, sous contrat, peut permettre d'atténuer le risque à long terme. © 2012 Canadian Agricultural Economics Society.
Le Pape O.,Agrocampus Ouest |
Bonhommeau S.,French Research Institute for Exploitation of the Sea
Fish and Fisheries | Year: 2015
Coastal zones are productive areas that serve as nursery grounds for a large number of marine species. However, the processes involved in survival success during the juvenile phase are not well-known. Some authors suggest that the availability of prey is important to support the production of pre-recruit fish whose fitness is enhanced through optimal feeding conditions. Accordingly, recruitment is limited by the carrying capacity of the nursery habitat. In contrast, other authors state that the carrying capacity of the nursery grounds is not fully exploited, suggesting that there is no effect of food limitation. This study combines an overview of the literature, focused on flatfish that are especially dependent on coastal and estuarine nursery grounds, an extension to other marine fishes and a modelling approach on growth and survival of juvenile fish to explore the controversy of food limitation in their nursery grounds. We demonstrate that the relative lack of growth limitation observed for young marine fishes at the individual scale is related to an observational bias: fish have been affected by size-selective mortality linked to food limitation, but only surviving individuals are observed. As the population is skewed towards the faster-growing juveniles, the growth of survivors remains close to optimal, even when food resources are limited. Food limitation is of major influence in determining the carrying capacity of the nursery habitat. To sustain marine fish populations and related fisheries, management action is needed to protect coastal and estuarine areas and maintain or restore nursery productivity. © 2013 John Wiley & Sons Ltd.
Husson F.,Agrocampus Ouest |
Josse J.,Agrocampus Ouest |
Saporta G.,French National Conservatory of Arts and Crafts
Journal of Statistical Software | Year: 2016
The Dutch and the French schools of data analysis differ in their approaches to the question: How does one understand and summarize the information contained in a data set? The commonalities and discrepancies between the schools are explored here with a focus on methods dedicated to the analysis of categorical data, which are known either as homogeneity analysis (HOMALS) or multiple correspondence analysis (MCA). © 2016, American Statistical Association. All rights reserved.
Derde M.,Agrocampus Ouest
Biochimica et biophysica acta | Year: 2015
Lysozyme is mainly described active against Gram-positive bacteria, but is also efficient against some Gram-negative species. Especially, it was recently demonstrated that lysozyme disrupts Escherichia coli membranes. Moreover, dry-heating changes the physicochemical properties of the protein and increases the membrane activity of lysozyme. In order to elucidate the mode of insertion of lysozyme into the bacterial membrane, the interaction between lysozyme and a LPS monolayer mimicking the E. coli outer membrane has been investigated by tensiometry, ellipsometry, Brewster angle microscopy and atomic force microscopy. It was thus established that lysozyme has a high affinity for the LPS monolayer, and is able to insert into the latter as long as polysaccharide moieties are present, causing reorganization of the LPS monolayer. Dry-heating increases the lysozyme affinity for the LPS monolayer and its insertion capacity; the resulting reorganization of the LPS monolayer is different and more drastic than with the native protein. Copyright © 2014 Elsevier B.V. All rights reserved.
Bonneau M.,Agrocampus Ouest |
Lebret B.,Agrocampus Ouest
Meat Science | Year: 2010
The present paper reviews the available information on the eating quality of pork from the perspective of production systems considered at farm level. Among the specifications differentiating systems having a claim on eating quality, breed, feeding strategy, rearing conditions and slaughter age/weight of the pigs may influence pork eating quality. Specific genetic X environment interactions such as the use of slow growing-fat local breeds reared in extensive conditions, as encountered in local Mediterranean systems, lead to high eating quality of pork and pork products Organic production per se has little influence on the eating quality of pork. Welfare-oriented specifications such as enriched living environment, outdoor access or free-range rearing have limited consequences on pork quality. Because boar taint negatively impacts the consumer acceptability of pork, a total ban on castration to improve animal welfare would be a real challenge for the management of pork quality in those countries where entire male pig production is not currently common. © 2009 Elsevier Ltd. All rights reserved.