Etude cinétique et optimisation multicritères du couplage déshydratation imprégnation par immersion (séchage convectif de la poire, la pomme et l'abricot)

Ce travail avait pour objectif l'étude de l'impact des deux procédés : la déshydratation imprégnation par immersion (DII) et le séchage convectif menés séparément ou combinés sur les transferts couplés d'eau et de saccharose et les principaux critères de qualité de fruit (écart de couleur, teneur en phénols totaux (PT), teneur en acide ascorbique (AA), retrait volumique, activité de l'eau) en prenant la poire Conférences comme modèle. L'effet des procédés sur les morceaux de poire a été appréhendé selon deux approches : (i) une étude globale de l'impact des variables de commandes sur la qualité du produit fini et (ii) une étude cinétique des composés d'intérêt nutritionnel et de la qualité (couleur, retrait, activité de l'eau).Un plan d'expériences composite centré à quatre facteurs et cinq niveaux a été établi (concentration en saccharose de la solution osmotique : 25-65%, température de DII : 20-60 C, durée de la DII : 0,5-6,5 h, température du séchage convectif : 30-70 C) pour étudier l'effet global des procédés sur le produit fini. En DII, les paramètres Brix, durée et la température de la solution ont un effet significatif (p < 0,01) sur les pertes en eau, le gain en soluté et les attributs de qualité de morceaux de poire. Les pertes en AA sont plus élevées que les pertes en PT et sont essentiellement dues à l'oxydation et à l'entraînement par l'eau. Durant le séchage convectif, les pertes en PT et en AA dépendent plus de la durée du procédé que de la température d'exposition. Elles atteignent respectivement 80% et 34% après 10 h de séchage à 30 C. Le changement de couleur de morceaux de poire dépend de la durée et de la température de traitement et est plus prononcé en fin de séchage. Des modèles quadratiques prédictifs ont été proposés pour relier les variables de réponse (aw, différence de couleur, perte en PT et durée totale de traitement) aux paramètres opératoires des deux procédés étudiés. Cependant, la perte en AA décroit linéairement avec la durée de DII. Une optimisation multicritères en utilisant la méthodologie des surfaces de réponse (MSR) a été proposée (pertes minimales en PT et en AA, durée totale du traitement et différence de couleur réduites et une aw inférieure à 0,6) pour la combinaison DII/séchage. Les conditions optimales sont : solution osmotique à 28C et 25Brix, une durée de DII de 30 min et un séchage convectif à 60 C. Par ailleurs, les effets de la température (30, 45 et 60 C) et de l'imprégnation en saccharose par DII (10 et 65 min, 70Brix, 30 C) sur les isothermes de désorption et sur la température de transition vitreuse (Tg) de morceaux de poires, de pommes et d'abricots ont été déterminés. L'imprégnation en saccharose du tissu végétal atténue l'influence de la température sur sa capacité de sorption. Elle engendre un effet dépresseur de l'activité de l'eau et une augmentation de l'hygroscopicité de la poire, la pomme et l'abricot à température élevée. Les isothermes de désorption des abricots frais et enrichis en saccharose présentent un croisement des courbes marquant l'inversement de l'effet de la température sur les isothermes. La Tg dépend de la température, de la teneur en saccharose et de la teneur en eau des fruits. Pour une teneur en eau constante, l'augmentation de la température et la durée de DII se traduisent par l'augmentation de la Tg. Les digrammes de phase (Tg=f(X) et Tg=f(aw)) des fruits ont été établis à 30, 45 et 60C et les teneurs en eau critiques ainsi que les activités d'eau critiques ont été déterminées. Une teneur en eau en fin de séchage inférieure ou égale à 0,02 g/g M.S. est recommandée pour l'obtention de morceaux de fruit stables aux niveaux microbiologique, physicochimique et rhéologique.The aim of this work was the study of the impact of both drying processes: dehydration-impregnation by soaking (DIS) and convective drying performed separately or in combination on mass transfers of water and sucrose and on the main quality characteristics of the fruit (total difference of colour, total phenols (TP) and ascorbic acid (AA) contents, shrinking, water activity) by taking the pear Conference as a model. The processes effect on the pieces of pear was apprehended according two approaches: (i) a global study of the impact of the variables of commands on the quality of finished product and (ii) a kinetic study of nutritional compounds and the quality (colour, shrinkage, and water activity). Central Composite Design with four factors (sucrose concentration: 25-65 %, temperature: 20-60 C, immersion time: 0.5-6.5 hr and drying temperature: 30-70 C) at five levels each was used for pears processing. During DIS, the variables: immersion time, temperature and concentration of sucrose solution had a significant effect (p<0.01) in the loss of water, the solid gain and the quality attributes of pears. The losses in AA are higher than those in TP and are essentially due to the oxidation and the leaching with water. During the convective drying, the losses in TP and in AA depend more on the time of the process rather than the temperature of exposition. They reach respectively 80% and 34% after 10 h of drying at 30 C. The color change of pear depends on the time and temperature of treatment and is more pronounced at the end of drying. Predictive and quadratic models were suggested to link the responses variables (aw, total colour difference, TP loss and total time treatment) to operational parameters of both studied processes. The losses in AA decrease linearly with the duration of DIS. A multicriteria optimization using response surface methodology (RSM) was proposed (minimal losses in TP and in AA, reduced total processing time and total difference in colour and an aw inferior to 0.6) for the combination DIS/convective drying. The optimal conditions are: osmotic solution at 28C and 25Brix, a DIS lasting 30 min and a convective drying at 60 C. Otherwise, the temperature effects (30, 45 and 60 C) and the sucrose impregnation by DIS (10 and 65 min, 70Brix, 30 C) upon the desorption isotherms and the transition temperature (Tg) of pears, apples and apricots were determined. The sucrose impregnation diminishes the influence of temperature on its sorption ability. It generates a depressing effect on water activity and a rise of pear hygroscopicity, apple and apricot at a high temperature. The desorption isotherms of fresh and sucrose impregnated apricot present a crossing of curves which mark the inverse of the effect of temperature on isotherms. The Tg depends on the temperature, the sucrose content and the fruit water content (X). For constant water content, the rise of temperature and of the duration de DIS result in the increase of Tg. The phase diagrams (Tg=f(X) et Tg=f(aw)) of fruits were established at 30, 45 and 60C and the critical water content as well as the critical water activities were determined. Water content at the end of drying inferior or equal to 0.02 g/g d.b. is recommended to obtain stable fruit pieces at microbiological, physiochemical and rheological levels.PARIS-AgroParisTech Centre Paris (751052302) / SudocSudocFranceF

Influence of air drying temperature on kinetics, physicochemical properties, total phenolic content and ascorbic acid of pears

Communication oraleInfluence of air drying temperature on kinetics, physicochemical properties, total phenolic content and ascorbic acid of pears. 1. Euro-Mediterranean Symposium for Fruit and Vegetable Processin

Moisture desorption isotherms and glass transition temperatures of osmo-dehydrated apple and pear

The aim of this work was to evaluate osmo-dehydrated pear and apple stability on the basis of combined data of moisture desorption isotherms and glass transition temperatures (Tg) investigated in the temperature range of 30-60 degrees C. Parallelipedic pieces of pears and apples were osmo-dehydrated at 30 degrees C in sucrose syrups at 70% during 65 min. To study their hygroscopic properties behavior, the osmo-dehydrated fruits were stored in static desiccators at 30,45 and 60 degrees C, and relative humidities ranging from 6 to 80%. The Gmodel satisfactory described the relationship between the water activity (aw) and water content (X) of osmo-dehydrated fruits (r(2) >= 0.994). Differential scanning calorimetry was used to measure Tg of osmo-dehydrated fruits conditioned at various water activities. A strong plasticizing effect of water on Tg was found with a large reduction of Tg when the water content increased. The dependence of Tg on water activity data was satisfactory correlated by the Roos model (0.993 <= r(2) <= 0.999). Whereas the Tg similar to X-w was adequately described by Gordon and Taylor model (0.898 <= r <= 0.990). The changes of Tg similar to aw and Tg similar to X-w were established and the critical values of water contents were determined for the investigated range of temperature. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Influence of process variables on colour, bulk density, porosity, shrinkage, total phenols and vitamin C of pear during osmo-convective drying

Influence of process variables on colour, bulk density, porosity, shrinkage, total phenols and vitamin C of pear during osmo-convective drying. 3. Séminaire Maghrébin sur les Sciences et les Technologies de Séchag

Influence of sucrose composition on water sorption isotherms and on glass transition in apricots

Influence of sucrose composition on water sorption isotherms and on glass transition in apricots. 1. Euro-Mediterranean Symposium for Fruit and Vegetable Processin

Expérimentation d'un modèle d'éducation thérapeutique pour patients polypathologiques dans les maisons de santé pluriprofessionnelles

International audienceIntroduction: The high prevalence of chronic diseases is accompanied by an underestimation of multimorbidity. This reality is also found in primary care. The therapeutic patient education (TPE) program for multimorbidity, based on a model developed by the Education and Health Practice Laboratory (LEPS, EA 3412), has been proposed by the Mutualité Sociale Agricole (MSA), the french health insurance body for farmers, to patients with several chronic diseases attending multi-professional primary care centers (MSPs). It was tested in 2015–2016.Objectives: To design, validate and experiment an operational model of TPE for multimorbidity patients with cardiovascular disease, diabetes, and/or chronic obstructive pulmonary disease, educated in two MSPs. Method: Assessment of patients by questionnaire (before and immediately after education) focused on their knowledge of the causes and means for managing their illnesses, their feelings of trust, mastery and efficiency. Six months after the TPE program, patients were interviewed on the competencies they had acquired.Results: 47 patients were evaluated (35 patients had 2 pathologies, 11 had 3 and 1 had 4). After education, an increase in their useful knowledge has been observed: explanation of the diseases and their causes (T1: 38,5%; T2: 88,4%, p < 0,001), explanation of the effect of each drug (T1: 50%; T2: 100%, p < 0,001). They also expressed their confidence in the treatments they take (T1: 84,1%; T2: 95,4%, p < 0,05). They declared themselves capable of recognizing their own crises (T1: 46,1%; T2: 84,6%, p < 0,001), being able to face them (T1: 42,3%; T2: 88,5%, p < 0,005) and knowing who to count on to get help (T1: 84,6%; T2: 100%, p < 0,05). Among the skills acquired for the day-to-day management of their diseases, we notice regular physical activity T1: 46,1; T2: 80,8%, p < 0,001), dietary adaptation (T1: 46,1%; T2: 92,3%, p < 0,001), ability to manage different treatments (T1: 96,2%; T2: 100%, p < 0,01).Conclusion: Multimorbidity is a challenge for TPE. The model of TPE program for multimorbidity that we designed and tested seems to provide an educational response to the needs of these patients. Further research is needed to confirm the effectiveness and strength of the model.Introduction : La forte prévalence des maladies chroniques s'accompagne d'une sous-estimation des multimorbidités. Cette réalité se retrouve dans les soins de premier recours. Le programme d'éducation thérapeutique (ETP) polypathologie, d'après un modèle conçu par le laboratoire éducation et pratiques de santé (LEPS, EA 3412), a été proposé par la Mutualité sociale agricole (MSA) à des patients atteints de plusieurs maladies chroniques fréquentant des maisons de santé pluriprofessionnelles (MSP). Il a été expérimenté en 2015–2016.Objectif : Concevoir, valider et expérimenter un modèle opérationnel d'ETP polypathologie pour patients atteints de maladies cardiovasculaires, diabète, et/ou broncho-pneumopathie chronique obstructive, éduqués dans deux MSP. Méthode : L'évaluation des patients par questionnaire (avant et immédiatement après éducation) a porté sur leurs connaissances des causes et des moyens de gestion de leurs maladies, sur leurs sentiments de confiance, de maîtrise et d'efficacité. Les compétences acquises ont été interrogées six mois après l'ETP.Résultats : 47 patients ont été évalués (35 patients ont 2 pathologies, 11 en ont 3 et 1 en a 4). Après éducation, on constate un accroissement de leurs connaissances utiles : explication des maladies et de leur causes (T1 : 38,5 % ; T2 : 88,4 %, p < 0,001), explication du but de chacun des médicaments (T1 : 50 % ; T2 : 100 %, p < 0,001). Ils expriment leur confiance dans les traitements qu'ils prennent (T1 : 84,1 % ; T2 : 95,4 %, p < 0,05). Ils déclarent être capables de reconnaître leurs propres crises (T1 : 46,1 % ; T2 : 84,6 %, p < 0,001), de savoir y faire face (T1 : 42,3 % ; T2 : 88,5 %, p < 0,005) et de savoir sur qui ou quoi compter pour obtenir une aide (T1 : 84,6 % ; T2 : 100 %, p < 0,05). Parmi les compétences acquises pour la gestion quotidienne de leurs maladies, on note la pratique d'une activité physique régulière (T1 : 46,1 ; T2 : 80,8 %, p < 0,001), une adaptation de l'alimentation (T1 : 46,1 % ; T2 : 92,3 %, p < 0,001), la capacité à gérer un traitement pluriel (T1 : 96,2 % ; T2 : 100 %, p < 0,01).Conclusion : La polypathologie constitue un défi pour l'ETP. Le modèle de programme d'ETP polypathologie que nous avons conçu et expérimenté semble pouvoir apporter une réponse pédagogique aux besoins de ces patients. D'autres recherches sont nécessaires pour confirmer l'efficacité et la robustesse du modèle

Characterization of C69R variant HBsAg: effect on binding to anti-HBs and the structure of virus-like particles

International audienceSeveral variants of the major ‘‘a’’ determinant of the HBsAg, the main target of HBV neutralization by antibodies, have been described. However, mutations out- side this region have not been as thoroughly investigated. During the genotyping of HBV from Tunisian patients with chronic hepatitis B, we identified a variant with a C69R substitution in the cytosolic loop of the S protein, resulting in a change in the hydrophobicity profile compared to the wild-type HBsAg. Wild-type and mutant HBsAgs were produced in Saccharomyces cerevisiae and recombinant proteins were tested for their ability to correctly self- assemble into virus-like particles (VLPs), and their ability to bind to HBs antibodies. The C69R substitution resulted in a decrease in binding to commercial anti-HBs antibod- ies, and although the variant appeared to assemble properly into VLPs, the average size of the particles was larger than that of the wild-type HBsAg. Prediction of the tertiary structure of the C69R mutant revealed a change in the first (aa 60-70) and the second loop (aa 110 to 120) compared to the wild-type protein. Furthermore, we showed by an isothermal titration calorimetry assay that the interaction between the wild-type HBsAg and the anti-HBs antibody was exothermic, whereas that with the mutant C69R was endothermic, indicating an effect on the binding affinity

Mixed Coagulant-flocculant Optimization for Pharmaceutical Effluent Pretreatment Using Response Surface Methodology and Gaussian Process Regression

peer reviewedWastewater from the Antibiotical-Saidal pharmaceutical plant (Medéa) was pretreated by coagulation-flocculation using copper sulfate (CuSO4), iron chloride (FeCl3), and mixture of the two salts combined in a 1:1 (v/v) ratio in the present study. Response surface methodology (RSM) was used to optimize pH and coagulant dosage as independent variables, while dissolved organic carbon (DOC), absorbance at 254 nm (UV 254), and turbidity were provided as dependent variables in the central composite design (CCD). Then, the databases of the three treatments were combined in a single database to create a general model valid for the three treatments at the same time, and to predict the reduction rates of DOC, UV254, and turbidity, using the Gaussian process regression coupled with the dragonfly optimization algorithm (GPR-DA). To have the best model obtained between RMS and GPR-DA, an experimental validation was carried out after having had the optimal conditions of each type of coagulant, using the multi-objective optimization technique. The results of the experimental validation show the superiority of the GPR-DA model compared to the RSM model. Also, the results show that the mixed coagulant (CuSO4+ FeCl3) obtain better results than CuSO4 or FeCl3 alone with a treatment efficiency equal to 92.68% at pH = 5 and dosage = 600 mg/L, and the reductions in DOC, UV 254 and turbidity are 97.32%, 82.90% and 96.47%, respectively