Non destructive sensing of peach firmness

Upon the different criteria that can be used to test peach maturity, firmness appears the most reliable. In this study, we develop a sensor able to non-destructively determine peach firmness. The principal is the one of micro-deformations : a moving tip submitted to a string constraint emerges from a reference surface (the probe). When the probe is applied on the fruit, the tip is moved according to the texture of the flesh. If the flesh is hard, the displacement of the tip is important. In the contrary, the tip can even not move at all. All the intermediary positions are possible. The results got with this apparatus are very satisfying : if the fruits are classified within 3 classes, the performance is as high as 92,5 % of well classified fruits. / Dans cette étude, nous avons développé un capteur non destructif pour mesurer la maturité des pêches. Le principe utilisé est celui de micro déformations de la pêche. Un embout, porté par une jauge de contrainte, et appliqué sur le fruit. Si le fruit est mûr, l'embout s'enfonce de quelques centièmes dans le fruit, s'il est plus ferme l'enfoncement est moindre. La valeur de l'enfoncement est lié à la maturité du fruit. Les résultats obtenus sont très satisfaisants. Si les fruits sont classés en trois classes de maturité, la performance de l'appareil est de plus de 92,5 % de fruits bien classés

Un nouveau capteur industriel de mesure du temps de coagulation du lait: le coagulometre

National audienc

Infrared technology for food industry and agricultural uses: on line applications

Emphasis on near infrared lasts for long, but new technology in the infrared area (both mid infrared or MIR and Near Infrared or NIR) open new applications. A user guide has been built in order to help the food engineer to choose a technique able to help him in his process control, especially according to his on-line constraints and on his performances requirements. This chart has been applied to two examples : the constituent analysis of a fermentation thanks to Mid infrared spectrometry and the non destructive ultrafast measurement of sugar in fruits thanks to a diode array spectrometer. In the first experiments, good accuracies were obtained, which makes of MIR a potential tool for rapid process control. In the second example, fiber optics are used in order to optimize the throuput of the optical system and to allow multiplexing. The cost of this apparatus would be so low that it could be available even by small conditionning stations. Abstract of the paper N° 920602. / L'intérêt de la spectroscopie proche infrarouge existe depuis longtemps mais les nouvelles technologies dans le domaine infrarouge (à la fois moyen et proche infrarouge) ouvrent de nouvelles applications. Un guide a été construit de manière à aider l'ingénieur agro-alimentaire à choisir la technique la plus appropriée pour l'aider dans le contrôle de procédé, notamment en fonction de ses contraintes en ligne et des performances requises. Ce guide est appliqué à 2 exemples : analyse des fermentations par moyen infrarouge et mesure rapide du sucre dans les fruits. Abstract de la communication N° 920602

Traitement mathematique du signal du coagulometre pour la mesure du temps de floculation du lait

National audienc

Three-dimensional reconstruction of metal replicas of the Helicobacter pylori vacuolating cytotoxin

The Helicobacter pylori vacuolating cytotoxin (VacA) forms high molecular weight homooligomers which contain either six or seven copies of a 95-kDa polypeptide, Electron microscope visualization of carbon platinum replicas of quick-freeze, deep-etched, preparations of VacA has revealed that the oligomers are arranged in flower-like structures with six-or sevenfold radial symmetry depending on the number of 95-kDa oligomers that they contain. Each monomer is structured in two subunits of 37 and 58 kDa connected by an exposed loop which is a site for proteolytic cleavage. In preparations of VacA which had undergone extensive cleavage at the exposed loop, oligomers of both six-and sevenfold symmetry which appeared flatter were observed; these latter were interpreted as molecules which had lost a complete set of one of the subunits, We exploited a 3D reconstruction of metal replicas of quick-freeze, deep-etched, oligomers, representing the four types of molecules described. All the molecules appear to adhere with the same face toward the mica, Images of rotary shadowed oligomers were processed by multivariate statistical analysis to evidence clusters of equivalent and homogeneous oligomers, 3D reconstructions of the replicas so classified were performed by random conical tilt tomography. In the case of intact molecules (not cleaved) the reconstructions represent both the outer and the inner surfaces of the mold; the latter gives a reasonably accurate sense of the upper surface of the VacA oligomers, These data support the hypothesis that VacA is an AB type toxin and suggest a model in which the smaller of the two subunits is arranged in a uniform ring on the surface of the molecule in such a way as to contribute to the overall stability of the molecule

Spectromètre optique, en particulier spectromète optique autonome et portable

Spectromètre optique autonome et portatif, destiné à analyser un spectre lumineux rétro diffusé par un échantillon éclairé, afin d'en déduire une teneur d'au moins un composé constituant l'échantillon, ledit spectromètre étant organisé autour d'un axe optique et comprenant : - une zone cible centrée sur ledit axe optique, - une pluralité de capteurs optiques visant la zone cible, - une chambre de mesure opaque comprenant : - une ouverture centrée sur ledit axe optique, - au moins un filtre diffuseur obstruant ladite ouverture, - un fond intérieur apte à accueillir la pluralité de capteurs optiques, - un dispositif d'éclairage principal, apte à éclairer l'échantillon. Méthode d'utilisation d'un tel spectromètre