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Dijon, France

Savary G.,CNRS Organic and Macromolecular Chemistry Research Unit | Moreau C.,French National Institute for Agricultural Research | Cayot N.,AgroSup Dijon
Food Research International

The gelation mechanism of carrageenan depends on the amount and nature of the polysaccharide, and is cation sensitive. From a rheological approach, this specificity leads to different textural properties. In composite gels with carrageenans, starch and sucrose, the presence of κ/κ2-carrageenan, even at low levels, has an impact on textural and structural properties. In this study, rheological and diffusion NMR measurements were performed on composite gels to probe gel structure at the macro- and micro-scale. Variations were made in the gel composition by varying the carrageenan content and the nature of the polysaccharide and cations. We showed that all the factors that increased the rigidity of the composite gels - polysaccharide content and specific cations - decreased significantly the diffusion of small molecules such as sucrose and ethyl butyrate. © 2009 Elsevier Ltd. All rights reserved. Source

Gardarin A.,French National Institute for Agricultural Research | Guillemin J.-P.,AgroSup Dijon | Munier-Jolain N.M.,French National Institute for Agricultural Research | Colbach N.,French National Institute for Agricultural Research
European Journal of Agronomy

In fields, the timing of weed emergence flushes is mostly related to the timing and rate of seed germination, which depend on soil temperature and water potential as well as soil tillage and crop sowing date. Base temperature and base water potential for seed germination are parameters required in weed dynamics models to take into account the effects of soil conditions on weed demography. Since these parameters are difficult to measure, our objective was to develop a method for estimating them from easily accessible information. Data on base temperature and base water potential for germination were collected from the literature for 28 weed species. Correlations were then searched for between these parameters and (i) the species ecological indicator values of Landolt and Ellenberg for temperature and moisture and (ii) dates of the onset and end of weed emergence based on experts' knowledge. Both base temperature and base water potential for germination were partially correlated with the species indicator values found in the literature. These correlations explained however only a small proportion of the variance of base temperature and water potential. In contrast, the base temperature of spring-emerging species was highly correlated with the mean soil temperature at the mean onset date of each species' spring emergence flush. Water potential for germination was higher for species requiring high base temperature. The date of spring emergence onset of a species, which can be easily assessed from experts' knowledge, can thus be used to estimate their base temperature and then their base water potential for germination. © 2009 Elsevier B.V. All rights reserved. Source

McDonnell C.K.,Teagasc | McDonnell C.K.,University College Dublin | Allen P.,Teagasc | Morin C.,AgroSup Dijon | Lyng J.G.,University College Dublin
Food Chemistry

The aim of this study was to assess the effect of power ultrasound (US) treatment (4.2, 11 or 19 W cm-2 for 10, 25 or 40 min) on water-protein interactions during the salting of pork. All US treatments increased the protein extraction above that of the control (p < 0.001), with the exception of 4.2 W cm-2 for 10 and 25 min. Differential scanning calorimetry indicated myosin denaturation at the surface of the sample treated with the highest power (19 W cm-2, 40 min). There was no effect on water binding capacity assessed by centrifuge, however, low-field nuclear magnetic resonance T21 relaxation was increased by 19 W cm -2 (p < 0.05). No changes to the meat matrix were evident by light microscopy. Findings indicate that US salting could be a surface phenomenon which can accelerate mass transfer and extract protein but denature myosin at high power inputs. Potential could exist for US to enhance conventional curing techniques. © 2013 Published by Elsevier Ltd. Source

Cerf M.,French National Institute for Agricultural Research | Guillot M.N.,French National Institute for Agricultural Research | Olry P.,AgroSup Dijon
Journal of Agricultural Education and Extension

How do change agents deal with the diversity of farmers' attitudes towards the future of agriculture? How do they themselves cope with change and understand their role as change agents? We chose a comprehensive, action-training approach to answer such questions and worked with agents belonging to two different extension networks. The agents acknowledged their historically built professional models and discussed their professional situations in relation to the need to develop new skills and to address new audiences. Some dimensions of these situations were pointed out as crucial in the change process: (1) the agent's position among farmers and those who act to change farming practices at local level; (2) the tension between the agent's engagement in promoting more environmentally-friendly practices, and the role that managers and farmers assign to the agent; and (3) the way of combining scientific and technical knowledge with farmers' own knowledge. Our work also highlighted the diversity of the agents' points of view on change at farm level (discontinuity versus continuity) and the way to handle it: respectively by making the discontinuity visible and manageable at farm level, or by supporting a step-by-step management of change at cropping-system level. The added value has been to develop a method which enables advisers to learn together from their professional situations, and thus to show the need to investigate how the agent's subjectivity is a key driver of a change intervention. © 2011 Wageningen University. Source

Fisk I.D.,University of Nottingham | Boyer M.,AgroSup Dijon | Linforth R.S.T.,University of Nottingham
European Food Research and Technology

The release of volatile compounds, such as aroma, from a food material during hydration is of wide relevance to the food industry. To this end, dry powders of varying chemical composition were hydrated in a controlled system to investigate the impact of varying composition (protein, lipid and carbohydrate) on the delivery rate of volatile compounds to the headspace. Additional lipid and carbohydrate reduced the concentration of volatile compounds in the headspace and accelerated their rate of delivery to the headspace. Protein had no measurable impact. Of the volatile compounds measured, 2,3 butanedione and acetaldehyde were shown to be released slowly into the headspace, and pyrrol, methyl acetate and pyridine were released rapidly; this differential release rate was strongly correlated with hydrophobicity and would indicate that during hydration there is a temporal dimension to the relative abundance of volatile compounds in the headspace. © 2012 The Author(s). Source

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