Search results for "milieu"
showing 10 items of 19813 documents
16S rDNA analysis for characterization of denitrifying bacteria isolated from three agricultural soils
2000
Bacteria capable of denitrification are spread among phylogenetically diverse groups. In the present investigation, molecular methods (amplified ribosomal DNA restriction analysis (ARDRA) and partial 16S rDNA gene sequencing) were used to determine the genetic diversity of culturable denitrifying soil bacteria. The purpose of this work was to study the microbial density and diversity of denitrifying communities isolated from two luvisols and a rendosol. The denitrifying bacterial density was significantly higher in the two luvisols (3x10(6) and 4x10(6) bacteria g(-1) dry soil) than in the rendosol (4x10(5) bacteria g(-1) dry soil). Denitrifying isolates from soils were grouped according to …
Statistical analysis of sensory profiling data. Graphs for presenting results (PCA and ANOVA)
2000
Abstract A principal component analysis is performed to analyse the matrix of median values, with 16 varieties in rows, and all descriptors in columns. Only texture descriptors contribute to the definition of the main axes. Six varieties are identified that score high on mealiness and low on moisture, the 10 other varieties are ordered according to a mashable axis which involves texture descriptors. Next we exclude texture descriptors since the main characteristics are already found, and mealy varieties since they are not suitable for steamed potatoes. A mixed linear model (ANOVA) with random subject effects is then used for each descriptor. Flavour and taste differences are found among the…
Cheese flavour : instrumental techniques
2004
This chapter discusses instrumental techniques to analyze cheese flavor. It focuses on recent advances made to study and identify the taste-active components present in the water-soluble fraction of cheese. A general procedure for the preparation of fractions involves an extraction of grated cheese by water followed by a fractionation scheme, generally adapted from the fractionation protocol used to isolate cheese nitrogen fractions in the study of proteolysis in cheese during ripening. However, as sub-fractions have to be evaluated sensorially to assess their relative sensory impact and try to link it to their chemical composition, a suitable eluent has to be used in the chromatographic st…
Screening individual ability to perform descriptive analysis of food products : basic statements and application to a camembert cheese descriptive pa…
1995
A battery of sensory tests is proposed to select potential descriptive panelists. This set of tests is flavor specific. Several abilities are examined: odor and taste recognition, odor memory, discrimination and descriptive capacities. A detailed example of such a battery to select a Camembert cheese descriptive panel is given. The objectives of each test are discussed. Stimuli are chosen to be consistent with the sensory properties which can be perceived in cheese. Score distributions demonstrate the discrimination among candidates for each test. Globally, results show the difficulty to find 20 panelists amongst about a hundred with good scores on each test. The panel leader has to choose …
Volatile components of dry-cured ham
1991
The volatile components of dry-cured ham were isolated by vacuum distillation and analyzed by gas chromatography-mass spectrometry. The structures of 76 molecules were identified by mass spectrometry, cochromatography, or measured Kovats indices. The compounds identified may come from the catabolism of the main constituent parts of the meat (glucids, lipids and protids) during the curing of the hams, from the pig feed, or from technological processes. The volatile compounds extracted from 50 g of ham according to the technique described correspond to a chromatographical surface equivalent to 0.12 mg of the dodecane internal standard, or approximately 2.4 ppm of the weight of the sample. Fla…
De la maison au " village" . Les origines de la morphologie de l'habitat dispersé dans les montagnes de la Savoie du nord
2002
Dans les hautes vallées savoyardes, le peuplement d'avant l'invasion touristique était caractérisé par une implantation en hameaux dispersés à travers le territoire communal. Dispersion relative en Savoie du sud (Maurienne, Tarentaise, Combe de Savoie) où les hameaux étaient fédérés par un « chef-lieu » qui était un véritable bourg ; dispersion fréquemment absolue en Savoie du nord (Faucigny, Chablais), où le chef-lieu n'avait souvent pas plus d'importance que les écarts. C'est aux massifs mo...
Microclimat, eau et production
1990
It is generally known that the whole of climatic factors affects directly the principal biological functions and the processes influencing crop yield. However, the control of these factors remains very difficult. Research is carried out adapting different crops to the average daily climatic characteristics and to their seasonal evolution instead of modifying the crops genetically and physiologically. Since all times the control of the factor water, not from rainfall but from irrigation, gives possibilities to modify directly the characteristics of the microclimate in the plant canopy.
Évaluation de l'efficacité externe de la formation des agriculteurs
1997
Alain Mingat und Nelly Stephan, Bewertung der externen Effektivität landwirtschaftlicher Ausbildung. In diesem Beitrag soill die externe Effektivität der Ausbildung der Landwirte bewertet werden. Dabei soll festgestellt werden, ob besser ausgebildete Landwirte effizienter als weniger gut ausgebildete sind. Die durchgeführte Untersuchung erlaubte die Wirksamkeit der Ausbildung in zwei Phasen zu untersuchen : zum Zeitpunkt der Niederlassung in einem landwirtschaftlichen Betrieb, wo der Landwirt die Ausrichtung seines Betriebs festlegt, und während dieser Niederlassung, urn die Fähigkeit zur Führung dieses Betriebs zu bewerten. Auch wenn die Anhebung des technischen Ausbildungsniveaus ein wich…
Crop nitrogen monitoring: Recent progress and principal developments in the context of imaging spectroscopy missions
2020
Abstract Nitrogen (N) is considered as one of the most important plant macronutrients and proper management of N therefore is a pre-requisite for modern agriculture. Continuous satellite-based monitoring of this key plant trait would help to understand individual crop N use efficiency and thus would enable site-specific N management. Since hyperspectral imaging sensors could provide detailed measurements of spectral signatures corresponding to the optical activity of chemical constituents, they have a theoretical advantage over multi-spectral sensing for the detection of crop N. The current study aims to provide a state-of-the-art overview of crop N retrieval methods from hyperspectral data…
Evaluation of taste compounds in water-soluble extract of goat cheeses
2000
Abstract The water-soluble fractions of two goat cheeses — one denomination of origin commercial trade mark (crottin de Chavignol®) and one bought in a local cheese making establishment (Bouton de culotte®) — containing many taste and flavour molecules were studied. Ultrafiltration with a 1000 Da threshold membrane, followed by gel filtration on Toyopearl HW-40S gel using water as eluent, led to the production of edible fractions. Physicochemical and sensory analysis of these fractions showed that the most tasty fractions contained, essentially, the free amino acids and mineral salts. Some of these tasty fractions also imparted some flavours. The quantity of small peptides (MW