Non-destructive measurements for evaluation of fruit quality

Different quality attributes are critical for consumer acceptability of fruits. So the fruit producers and distributors are particularly interested in the measurements of these criteria. It is possible thanks to reliable non-destructive techniques that allow replacing destructive measurements such as sensory analysis and instrumental measurements. This paper reviews the most successful results of different technologies

Extraction aqueuse et athermique de l'huile de lin assistée par décharges électriques de haute tension

The modern society recently became aware of the need to reduce pollutant emission in the environment and to have a sustainable development i.e. which meets the needs of the present without compromising the ability of future generations to meet their own needs. The substitution of fossil origin molecules by molecules from vegetables (biodegradable and renewable) could help to solve this problem at least in part : this would also limit our energy and/or material dependence. The lubricants, currently used in automobile industry, are mainly obtained from oil and pollute soils and water. Also, their substitution by bio-lubricants seems of a particu- lar importance. Vegetable oils are the main products likely to find industrial applications as alternative to petroleum products. However, the physicochemical properties (oxida- tion, temperature stability) of these natural substances are not yet competitive compared to those of usual lubricants. Nevertheless the linseed oil, once modified, could present interesting technical properties associated to a biodegradable character. To produce the oil initially contained in the seed cells, the oil industry developed around various pretreatments (mechanic, thermic, enzymatic) aiming at enhancing oil extraction, and expression as a central operation. A solvent extraction is then applied on the produced presscake. The objective of this study is to propose a new process for efficient oil extraction. This process had to be deprived of organic solvent (ecological aspect) and excessive heat treatment in order to preserve the various components of seed (economic aspect). First, we studied the effect of the seed crushing on expression. An optimal crushing allows to recover 70 % of the initial oil, which is comparable to industrial yield obtai- ned after crushing, cooking and expression. The study of seed maturity on expression highlights the need to have mature and dry seeds. An enzymatic preprocessing allows to discover a technological bolt due to the presence of mucilage (polysaccharides mixture) in the cuticule of seed. In order to extract mucilage, we propose an original solution based on the application of high voltage electric discharges (HVED) in water. In the second time, we sought to understand the phenomena during the electric discharge and calculate the energy consumption. After modeling of damped oscillations, recorded once the electric arc is created, we calculated the useful energy for the creation of the shock waves : the totality of the energy contained in the condenser is released during the discharge. It’s noticebale that only 25 % of this energy are used to generate shock waves. This treatment was then applied to the presscake produced after optimal crushing and expression. The mixture of presscake powder and water is treated by HVED then the resulting suspension is submitted to centrifugation to produce an emulsion as well as a solid residue. We then studied the effect of the pulse repetition frequency on the suspension and the produced emulsion physicochemical properties and on the composi- tion of the final products. The oil extraction kinetics and dry matter kinetics could be established and models are proposed. This process of extraction was finally optimized using an experimental design. Two successive treatments are thus applied by adjusting pH, temperature and mass of water. The total sum of applied impulses for the two treatments remaining constant and equal to 280. The oil extraction is favoured when the suspension is concentrated and the pH close to the average isoelectric pH of proteins of flax. Residues rich in oil (20 % of initial oil) and low in oil (2 % of initial oil) can be produced by adjusting the conditions of treatment. In conclusion, our study allowed us to propose a process with the following stages : crushing, expression, crushing, two treatments per electric discharge followed by centri- fugation. We propose two processes according to the results obtained with a forthcoming study concerning the separation of the produced emulsions.

Cocoa butter expression from cocoa nibs: effects of pre-treatment and process parameters on expression yield

Cocoa butter is obtained in industrial conditions from cocoa liquor using hydraulic presses with an average oil yield of 42%. Our objective was to study the extraction of cocoa butter directly from cocoa nib and to determine the influence of pressing parameters such as the type of beans (green bean (GB), roasted alkalised bean (RAB), roasted bean (RB)), temperature, and pressure on cocoa butter yield. The extraction result depends on the rheological behaviour of the cake, which can be modelised with a four component Kelvin-Voigt model. The RAB (with a yield of 39%) is easier to press than the RB (38%) and GB (13%). The global mean compressibility coefficients of the Kelvin-Voigt model are 1.4, 1.7 and 2.1 MPa respectively for RAB, RB, and GB

La sociologie et ses "sciences auxiliaires"

Après quelques modifications mineures, ce texte a été publié dans Aux frontières des attitudes. Textes en hommage à Guy Michelat, Paris, L'Harmattan, 2002, pages 205-223.International audienceAprès quelques modifications mineures, ce texte a été publié dans Aux frontières des attitudes. Textes en hommage à Guy Michelat, Paris, L'Harmattan, 2002, pages 205-223.Il présente une réflexion sur le rôle d'auxiliaires que jouent, en sociologie, des sciences souvent plus anciennes (telles que les mathématiques, l'histoire, la psychologie, la linguistique), et sur la place que ces sciences occupent effectivement dans la démarche des chercheurs en sociologie. Deux exemples sont développés : la classification automatique, et l'entretien non directif de recherches

Higher dimensional sieving for the number field sieve algorithms

International audienceSince 2016 and the introduction of the exTNFS (extended Tower Number Field Sieve) algorithm, the security of cryptosystems based on non-prime finite fields, mainly the paring and torus-based one, is being reassessed. The feasibility of the relation collection, a crucial step of the NFS variants, is especially investigated. It usually involves polynomials of degree one, i.e., a search space of dimension two. However, exTNFS uses bivariate polynomials of at least four coefficients. If sieving in dimension two is well described in the literature, sieving in higher dimension received significantly less attention. We describe and analyze three different generic algorithms to sieve in any dimension for the NFS algorithms. Our implementation shows the practicability of dimension four sieving, but the hardness of dimension six sieving

Designing Breakthrough Futures Projects in Educational Contexts: Process Methodology, Results and Lessons Drawn Using C-K Theory Framework

Novel education systems can today regenerate society as students can acquire methods and techniques helping build socio-economic models that displace old ones. How can educators with right methods and approaches free such students’ capacities? In this paper, a four days futures-oriented intensive workshop, powered by creativity process based on the C-K design innovation theory , was thoroughly conducted for agro-food graduating students at ISTIA . This BIOFUTURE workshop first conceptualized distant futures concept-ideas drawn from science fiction novels in environmental, health, bio-based, nutrition, and nanotechnologies domains. The assignment given to students was to design innovative futures projects from the initial concepts, graphically embody them, and write briefs and requirements originating future innovative projects. Three such projects were conceived: • HOMURGENCY - «A house that builds itself » • TIMETECH - «A man who can travel through Time» • WEIGHT REVOLUTION - «A slimming nutritive food » The workshop resulted into making available future concepts along with determining factors for a later implementation. Our approach introduces and implements a method to create concepts for the future in any domain of human activity and yields results that enable cooperative dialogues. The implemented process offers powerful means for futures studies. It shows ways to capacitate the democratizing of futures approach for wider dissemination into society through the agency of adequate educational systems that can be inserted within classical institutions

Les "défaillances de la mémoire" dans les enquêtes de victimation

"Memory Defficiencies" in Victimization Surveys: Responses in retrospective surveys are subject to different biaises associated largely with problems of memory recall. In victimaziation surveys, it is necessary to provide exact dates for the events mentioned. Among errors of date by respondents, Wesley G. Skogan distinguished three forms of chronological displacement (telescoping). On the basis of two victimization surveys in France, it is possible to show evidence for two of these forms (backward telescoping towards the reference period and forward telescoping within the period of reference), but not for the third (forward telescoping toward the period of reference). However, a more detailed analysis of one of these surveys reveals the possible influence of the seasonal variation of delinquency on the survey responses.Les réponses aux enquêtes rétrospectives sont sujettes à différents biais, liés pour une large part aux difficultés de remémoration. Dans les enquêtes de victimation, il est nécessaire de dater avec précision les événements rapportés. Parmi les erreurs de datation faites par les répondants, Wesley G. Skogan distingue trois formes de décalage temporel ("télescopage") ; à partir de deux enquêtes de victimation réalisées en France, il est possible de mettre en évidence deux de ces formes (télescopage arrière vers la période de référence, et télescopage avant à l'intérieur de la période de référence), mais pas la troisième (télescopage avant vers la période de référence). Par contre, une analyse secondaire plus fine de l'une de ces enquêtes révèle un effet possible sur les réponses des fluctuations saisonnières de la délinquance