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International audience; Fibre bundles are groups of elementary fibres glued together thanks to the middle lamella, and are the main fraction in plant fibre composites. In this study, relationship between the mechanical properties of flax fibre bundles, chemical composition and cellulose structure were investigated. To do so, a sequential biopolymer extraction was implemented. Fibre bundles were first depectinated by oxalate extraction, and then the hemicelluloses were extracted by LiCl/dimethyl sulfoxide (DMSO) and KOH. The oxalate extract consisted of homogalacturonans and type I rhamnogalacturonans, while the LiCl extract was composed mainly of glucomannans and the KOH extract of xyloglucans. The KOH stage resulted in the appearance of cellulose II in flax bundles. The extraction of pectin and hemicelluloses led to the disappearance of the middle lamella concomitant with a decrease in the tensile Young's modulus and maximum strength. Finally, the fibre bundle composition, ultrastructure and mechanical properties are discussed together in view of the thin middle lamella.

One of the best ways to increase the fiber content in the diet is supplementing wheat bran in bread. Wheat bran is known to affect the cellular structure of the dough, resulting in lower final bread volume. The present study was focused on analyzing the effect of wheat bran in throughout the bread making process; the results were compared with the recipe without bran. Wheat bran at different level viz., 0%, 8%, 16% and 24% w/w on flour basis was added into the wheat flour for the preparation of sandwich bread. Results showed that wheat bran significantly (p 0.05) affected the dough kneading parameters. Dough properties like stickiness and extensibility decreased with respect to increase in bran quantity. Unexpectedly, wheat bran enhanced the aeration of dough during mixing and the expansion rate of dough during fermentation. However, wheat bran decreased the specific volume of bread upto 10.81%, which was confirmed using 2D image analysis method where it was observed as the wheat bran alters the pore size distribution in bread crumb.

This study considered the effect of low energy microwave assisted freezing (MAF) on freezing time and quality attributes (microstructure, texture, drip loss and colour) of apple and potato. MAF of apples and potatoes was performed by applying constant microwave (MW) power (167 W/kg) and pulsed MW power (500 and 667 W/kg with 10 s pulse width and 20 s pulse interval resulting in an average power of 167 and 222 W/kg) during the freezing process. The temperature profile was monitored during the freezing process, and the microstructure was examined using X-ray micro-tomography and cryo-SEM. Other quality parameters such as texture, drip loss and colour were evaluated with thawed samples. It appeared that the freezing time was not affected by the MAF process. It is the first time that a MAF process is used for freezing plant-based products and showed that the application of microwaves during freezing process caused less freeze damage than the control condition.

The possibility of using near infrared hyperspectral imaging spectroscopy to quantify the water content in commercial biscuits was investigated. Principal component analysis was successfully applied to hyperspectral images of commercial biscuits to monitor their water contents. Variables were selected and water contents quantified using analysis of variance, followed by multiple linear regression, and the results were compared with those obtained with variable importance in projection partial least squares. Initially equal to 212, the number of variables after application of analysis of variance was equal to 10. Analysis of variance–multiple linear regression gave better results: the coefficient of determination (R2) was higher than 0.92 and the root mean square error of validation was less than 0.015. The “prediction images” obtained were very relevant and can be used to study biscuit defects. The methodology developed could be implemented at the industrial level for biscuit quality control and for online monitoring of the uniform distribution of water in the superficial layer of biscuits.

Freezing is an efficient and widely used method of food preservation. However, it can also cause irreversible damages at cellular level which in turn degrade the overall quality of the frozen food products. Therefore, qualitative and quantitative methods and technologies that will be able to evaluate with accuracy the freeze damage are of great importance. This review paper provides a comprehensive study of the methods that have been used to evaluate the freeze damage in fruits and vegetables. Further than the principles and the applications of those methods, the advantages and the limitations are also being discussed.

International audience; Experiments were carried out to study the effects of resting time (also well known as first proofing) on properties of dough and bread. Three resting times were used in the experiment: 0, 10 and 20 min. The results indicated that resting time significantly (p < 0.05) affects the properties of dough and bread. Porosity of the dough increased with increase in resting time. Decrease in the number of smaller bubbles and increase in the median pore area of the bubbles present in the dough was observed as the resting time proceeded. Significant decrease (p < 0.05) in torque value was observed with increase in resting time. Elastic recovery in terms of recoil strain was highest for 0 min resting followed by 10 and 20 min resting. Degassing was found to closely related to the air content of the dough as it was found that degassing increased with resting time. Bread specific volume and the porosity fraction increased, whereas median pore area in the bread crumb decreased with resting time.

Cake batter is a complex matrix essentially composed of lipids, egg, sugar and flour. The baking process plays an important role in the structural, textural and physical properties of cakes, as in all bakery products. Knowledge of the interactions between the ingredients and the induced phenomena, such as starch gelatinization and complexation, protein denaturation and competition for water at the different stages of batter baking, can be used as the key quality control of the end-product “cake”. The aim of this work was to investigate in depth the interactions between the different constituents of the batter by differential scanning analysis and heating cell X-ray diffraction on model and real batter systems. The results show that ‘three ingredients’ model systems can explain the different phenomena occurring during the baking of cake batter (real system). In the presence of sugar and fat, in a limited water system, starch gelatinization takes place in two steps, the largest part being combined with protein denaturation at high temperature.

International audience; The aim of this work was to evaluate the suitability of Near-Infrared Hyperspectral Imaging Spectroscopy (NIR-HSI) for the quantification of water content in commercial biscuits. Ten biscuits from two commercial brands were conditioned for one week in desiccators with different water activities controlled by different saturated solutions of salts. Biscuits were analyzed by NIR-HSI and resulting images are analyzed by Principal Components Analysis (PCA). A regression model is also computed using a small number of variables in order to predict moisture values for each pixel and reconstruct prediction images in false color. These results obtained by PCA show that the water content of the two brands of biscuits can be easily monitored by NIR-HSI. The determination coefficient (R-2) obtained by regression is higher than 0.925 and the Root Mean Square Error of Validation (RMSEV) less than 1.815. Prediction images are very relevant and can be used to study biscuits defects.

International audience; The collapse of the sides of sliced bread is a technological problem for the baking industry. This study aims to understand the possible link between bread structures, internal pressure gradient, waiting time in the pan before depanning, and side collapse. The collapse variation was measured using laser to get bread profiles, and using image analysis of bread slices. The pressure variation at the centre and at the periphery was measured, and the product structure was observed using X-ray microtomography. The collapse increases with the cooling time in pan. The pressure in the cells is always higher than pressure in ambiance and cannot explain the collapse. The bread structure measurements indicate that the collapse is probably due to the cells shrinking of bread sides cells. A complementary explanation is to be searched in the specific volume variation of the material constituting the dough and the bread during the baking and the cooling.

7 pages, 5 figures, 1 table.-- Available online 27 July 2011., Surface mechanical properties in fresh bread and during storage are greatly affected by the water plasticizing effect. However, the incidence of steaming during baking on the crust mechanical properties remains still unclear. The impact of the amount of steam (100, 200 and 400 ml) during baking on the crust features and water diffusivity was investigated. The amount of steam significantly (p, Authors acknowledge the financial support of Spanish Ministerio de Ciencia e Innovación (Project AGL 2008-00092 ALI) and the Consejo Superior de Investigaciones Científicas (CSIC). R. Altamirano-Fortoul would like to thank her grant to CSIC.

The freezing process at different steps of breadmaking is widely used to improve fresh bread availability for the consumer. The consequences of a freezing step on wheat dough and bread, and the way to reduce its negative impacts have been studied for years. Nevertheless, few works report studies on gluten-free doughs and breads. This work investigates the effect of unfermented frozen dough process on the properties of gluten-free dough and the quality of bread. Rheological oscillation tests showed that viscoelastic properties were unchanged for fresh and thawed doughs. However flow tests exhibit an effect of freezing on consistency index and flow behaviour index. Regarding the quality of bread, gluten-free breads obtained by frozen dough process had lower specific volumes and harder crumbs than conventional gluten-free breads (unfrozen breads). Distribution of gas cells was more homogeneous with a freezing step. Crust colour characteristics were also modified by the freezing step.

International audience; Empirical and fundamental rheological measurements were made on fresh and frozen dough to study the effects of freezing and frozen storage conditions. Frozen dough was stored at two different temperatures, −18 °C and −30 °C, and for 1, 7 and 28 days. Four dough formulations were tested: a standard wheat dough, a fibre-enriched wheat dough, a standard gluten-free dough and a gluten-free dough containing amaranth flour. No yeast was used in any formulation. The wheat dough is more affected by freezing and by the first days of storage whereas the gluten-free dough is more affected by a longer storage time. A storage temperature of −30 °C alters dough rheological properties more than a storage temperature of −18 °C. The addition of dietary fibres to the wheat dough increases its resistance to freezing and frozen storage. The addition of amaranth flour to gluten-free dough also increases its resistance to freezing but decreases its resistance to storage conditions.

The aim of this work was to investigate different methods of measuring the expansion of bread dough during fermentation and to develop a mathematical model to describe the variation of dough volume. Dough was prepared with wheat flour, salt, yeast, and selected amount of water (56%, 58%, and 60% w/w flour basis). Proving time was 1 h and proving temperature investigated were 25, 30, and 35°C. Dough volume was measured with three methods: (1) vertical expansion in a flask, (2) horizontal expansion between two plates, and (3) free expansion method. Volume was measured either using displacement transducer or from image analysis of pictures taken during expansion. All the methods allowed monitoring the increase in dough volume as a function of proving time. Small differences were observed between the three methods. Free expansion shows a faster start of expansion in comparison with the two other methods. Expansion curves have been fitted with a modified Gompertz model (Romano et al., J Food Eng 83:142–148, 2007). They exhibited three phases: a lag phase, followed by a linear phase (constant expansion rate), and finally a phase with a decreasing expansion rate. Statistical analysis of the set of data showed that the proving temperature had a significant effect on the different parameters calculated (volume expansion ratio, expansion rate), while the water content had no significant effect.

The formulation of gluten-free bread, which will be suitable for patients with coeliac disease, was optimized to provide bread similar to French bread. The effects of the presence of hydrocolloids and the substitution of the flour basis by flour or proteins from different sources were studied. The added ingredients were (1) hydrocolloids (carboxymethylcellulose [CMC], guar gum, hydroxypropylmethylcellulose [HPMC], and xanthan gum), and (2) substitutes (buckwheat flour, whole egg powder, and whey proteins). The bread quality parameters measured were specific volume, dry matter of bread, crust color, crumb hardness, and gas cell size distribution. Specific volume was increased by guar gum and HPMC. Breads with guar gum had color characteristics similar to French bread. Hardness decreased with the addition of hydrocolloids, especially HPMC and guar. Breads with guar gum had the most heterogeneous cell size distribution, and guar gum was therefore selected for further formulations. Bread prepared with buckwheat flour had improved quality: an increased specific volume, a softer texture, color characteristics, and gas-cell size distribution similar to French bread. Bread with 1.9% guar gum (w/w, total flour basis) and 5% buckwheat flour (of all flours and substitutes) mimicked French bread quality attributes.

The application of a global linearizing control algorithm to a multi-input–multi-output (MIMO) microwave thawing process is addressed in this paper. The objective is to control the defrosting time while preventing thermal runaway. A model of the heat transfer with a source term is proposed and is reduced to a system of nonlinear ordinary differential equations using a finite volumes scheme. The control consists of multivariable trajectory tracking, while acting on the microwave power and on the air velocity of a tangential cooling air blast. Experimental and simulation results are discussed in MIMO and single-input–single-output (SISO) configurations.

The influence of guar and xanthan gum and their combined use on dough proofing rate and its calorimetric properties was investigated. Fusion enthalpy, which is related to the amount of frozen water, was influenced by frozen dough formulation and storage time; specifically gum addition reduced the fusion enthalpy in comparison to control formulation, 76.9 J/g for formulation with both gums and 81.2 J/g for control, at 28th day. Other calorimetric parameters, such as Tg and freezable water amount, were also influenced by frozen storage time. For all formulations, proofing rate of dough after freezing, frozen storage time and thawing, decreased in comparison to non-frozen dough, indicating that the freezing process itself was more detrimental to the proofing rate than storage time. For all formulations, the mean value of proofing rate was 2.97 ± 0.24 cm3 min−1 per 100 g of non-frozen dough and 2.22 ± 0.12 cm3 min−1 per 100 g of frozen dough. Also the proofing rate of non-frozen dough with xanthan gum decreased significantly in relation to dough without gums and dough with only guar gum. Optical microscopy analyses showed that the gas cell production after frozen storage period was reduced, which is in agreement with the proofing rate results.

The freezing-thawing effect on the colour of raw fillets and on the texture of cooked fillets of European catfish (Silurus glanis) was studied. European catfish coming from two rearing conditions occurring in France were analysed by sensory and instrumental measurements. Fillets of European catfish became lighter, yellower and less bright after a freezing-thawing cycle. An increase in hardness and a decrease in resilience, disintegration and shear resistance were also highlighted after a freezing-thawing cycle. We could make the hypothesis that these variations of colour and texture were due either to mechanical damage or muscle protein denaturation. Fillets also became less juicy after a freezing-thawing cycle because of a loss of water-holding capacity.

International audience; The challenge of reducing the salt content while maintaining shelf life, stability and acceptability of the products is major for the food industry. In the present study, we implemented processing adjustments to reduce salt content while maintaining the machinability and the saltiness perception of sheeted dough: the homogeneous distribution of a layer of encapsulated salt grains on the dough during the laminating process. During sheeting, for an imposed deformation of 0.67, the final strain remained unchanged around 0.50 for salt reduction below 50%, and then, increased significantly up to 0.53 for a dough without salt. This increase is, in fine, positive regarding the rolling process since the decrease of salt content induces less shrinkage of dough downstream, which is the main feature to be controlled in the process. Moreover, the final strain was negatively correlated to the resistance to extension measured with a texture analyzer, therefore providing a method to evaluate the machinability of the dough. From these results, a salt reduction of 25% was achieved by holding 50% of the salt in the dough recipe to maintain the dough properties and saving 25% as salt grains to create high-salted areas that would enhance the saltiness perception of the dough. The distributor mounted above the rollers of the mill proved to be able to distribute evenly salt grains at a calculated step of the rolling out process. An innovative method based on RX micro-tomography allowed to follow the salt dissolving and to demonstrate the capability of the coatings to delay the salt dissolving and consequently the diffusion of salt within the dough piece. Finally, a ranking test on the salted perception of different samples having either an even distribution of encapsulated salt grains, a single layer of salt grains or a homogeneous distribution of salt, demonstrated that increasing the saltiness perception in salt-reduced food product could be achieved by a technological approach.

The colour of raw fillets and the texture of cooked fillets of European catfish (Silurus glanis) were studied. The catfish fillets resulted from two types of farming conditions used in France. Sensory and instrumental analyses were performed on the fillets. Two farming parameters were found to affect the colour and texture of European catfish fillets: water temperature and farming time. The shorter the farming time was, the lighter the fillets were, while a higher water temperature produced yellower and greener fillets. A higher water temperature and a longer farming time produced softer cooked fillets, while the higher the water temperature was, the less juicy the cooked fillets were. A good correlation and complementarity were observed between sensory and instrumental analyses of the colour and texture of European catfish fillets. Copyright © 2007 Society of Chemical Industry

Cake staling is a complex problem which has still not been fully understood. Starch polymers retrogradation, which is linked to biopolymers recrystallisation, is the most important factor affecting cake firmness in addition to water migration and fat crystallization. In this study, the effect of storage temperatures of 4 °C and 20 °C on starch retrogradation and fat recrystallization was investigated. Starch retrogradation can be tracked through changes in crystalline structure via X-rays diffraction as well as through melting of crystals via calorimetry. These techniques have been coupled to study the different phenomena occurring during staling. The results revealed that the storage of cakes at 20 °C for 25 days showed more starch polymer retrogradation and more intense fat recrystallization in the β form than at 4 °C. Consequently, the staling was delayed when a low storage temperature like 4 °C was used, which is recommended to retain high quality cakes during storage.

Cake batters - made of flour, egg, sugar and fat - are complex systems. Ingredients interactions and their impact on protein secondary structure and starch conformational structures were studied in model batter systems using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. The results showed the possibility of using the pregelatinized starch without affecting protein conformation. The estimation of protein secondary structure highlighted the prevalence of alpha-helical structures in the model batter system, while beta-sheets are predominant in flour systems as known in dough systems. The protein conformation in batter system is related to fat-protein interactions and could explain fat functionality in the final product. Starch crystallinity increased when each ingredient - except for pregelatinized starches - was added to the flour. Changes in starch conformation could be related to the redistribution of water between the batter ingredients. The overall results highlighted the importance of ingredients on the structural conformation of the batter polymers - starch and proteins - which could be the key factor to understand the functional properties of the batter. (C) 2015 Elsevier Ltd. All rights reserved.

Changes in the mechanical and micro-structural properties of cake batter as a function of formulation impact are described. Mechanical properties were investigated by batter rheology and cake texture. Confocal laser scanning microscope (CLSM), together with image analysis technique, was used to obtain the microstructure of batters and cakes. Results showed an increase in rheological moduli values with the addition of pregelatinized starch in the batter, while fat replacement by rapeseed oil decreased the moduli values of the batter. These changes in batter visco-elastic properties resulted in different cake structures. A significant increase in the surface area of the lipid domain has been observed on CLSM images for cakes using pregelatinized starches. This was explained by the fact that part or all of the pregelatinized starch was embedded in the lipid domain for these formulations. This fact may explain the expected softer texture of the cake using such starches. CLSM in combination with image processing has been proved as an applicable tool for examining and quantifying the fat and protein microstructure in batter and cake. Hence, it was possible to prove the dependency of the texture on the microstructure of the batter and the baked “cake”.

Despite its energetic interest, the use of microwaves for the thawing or temperage of food products presents a major drawback called thermal runaway. This is mainly due to the important gap between the dielectric properties of water in solid and liquid phases. A monitoring approach of the temperatures inside a foodstuff during microwave defrosting is therefore proposed to, in a first step, detect the critical phenomena of thermal runaway, and, in further work, to control it. An observer allowing to estimate the internal temperatures from the temperature of the surface has been developed. An Extended Kalman Filter, because of its simplicity of design, has been chosen, but this choice is not exclusive. The heat transfer with phase change and microwave effects is represented by a nonlinear distributed parameters system, and the observer is based on a standard finite volume scheme. The approach is experimentally carried out and validated during the defrosting of a block of tylose.

Software sensors (or observers) are especially useful when the state vector of a system cannot be measured. Widely employed for bioprocesses, they estimate the state variables from available measurements, which are functions of one or several state variables, provided that the observability property is checked. In food defrosting, an important challenge is to know the spread of the melting front inside the product, without any invasive measurement. The solution proposed in this paper is based on the design of software sensors able to estimate, from a superficial temperature measurement, the temperature distribution in the product, in real time, and consequently making it possible to determine the melting zone. The proposed solutions are, first, an extended Kalman Filter and, second, switched reduced Luenberger observers. The results are illustrated during the experimental thawing of a block of tylose in forced convection. © 2006 American Institute of Chemical Engineers AIChE J, 2006

Two enzyme-linked immunosorbent assay (ELISA) kits were evaluated for detection of porcine reproductive and respiratory syndrome (PRRS) antibodies in pooled sera and filter discs (FDs). Elution and incubation procedures and positive thresholds for both ELISAs were determined using FDs collected from sixty non-infected pigs and five pigs with low PRRS-antibody titres. Eighty paired samples (serum/FD) from infected pigs were titrated using both ELISAs. The authors thus showed that five sera or five FDs could be pooled in one test without significant loss of sensitivity. Compared to individual sera, method sensitivity was found to be 79% and specificity 97.5%, based on data from 200 pools of FDs collected on 15 PRRS-infected farms and 120 pools collected on 71 non-infected farms. To balance loss of sensitivity, two pools of five samples from sows and one pool of five samples from finishing pigs can be tested as an alternative to seven and five single sera, respectively.

UMR IATE Axe 2 : Structuration sous contraintes des agropolymères et réactivité des poudres; The agglomeration process controls the structure characteristics and end-use properties of the agglomerates.Understanding the mechanisms involved in the structuration of the food agglomerates still representsa real scientific stake. The objective of the present study is to improve the knowledge of theprocess–structure–properties relationships for the agglomeration of the durum wheat semolina. Pneumaticand mechanical agglomeration technologies were selected to generate different hydro–thermo–mechanical stresses during process. The agglomerates were characterized by their structures (electronmicroscopy, compactness, X-ray micro-tomography, starch gelatinization) and functional properties (colors,flowability, swelling, water solubility index). The results demonstrate specific effects of shear rate,process duration, and temperature on the physicochemical mechanisms occurring during processing. Afunctional mechanistic model was proposed to improve the description of the agglomeration mechanismsby considering the reversible and irreversible changes. This offers innovative potential to designnew agglomeration processes by considering the physicochemical reactivity of the food powders.

International audience; Starch is the major ingredient in cakes which are composed from flour, eggs, fat and sugar. Starch gelatinization plays an important role together with the protein network in defining the structure and quality of the final product. Rheology, texture and batter thermal and pasting properties were used to determine the effect of ingredients on batter and microcake (cake without bubbles) properties. The rheology of the batter was controlled by the water content which governed the phase transitions of the batter constituents. Differential scanning calorimetry clearly attested that ingredients addition shifted the gelatinization endotherm to higher temperatures. This was in agreement with the Micro-ViscoAmyloGraph (MVAG) measurements, where the batter ingredients addition to flour increased the pasting temperature and the peak viscosity. When 20% of the flour was replaced by the pregelatinized wheat or maize starch, a decrease in the peak viscosity and setback was observed which could explain the texture improvement. The association of these different techniques helped to better understand the effects of the different ingredients of the batter on starch properties that are important for improving the quality of these high sugar and fat content cakes.

Amyloglucosidase (AMG) is an enzyme that hydrolyzes starch into glucose units. AMG activity was tested in a model pie dough during the dough-making process (after mixing and sheeting) and during storage for 4 weeks at 4 °C. The activity was quantified by measuring the glucose content of dough and baked products using HPLC. The consequences of AMG activity on the sweet taste of the baked products (sensory ranking test) and on the rheological properties of the dough were studied and compared with a control dough formulated with sucrose. The results showed a significant production of glucose during the dough-making process and during baking when AMG was used. During the dough-making process, AMG activity was limited by the substrate. During baking, the substrate was no longer a limiting factor and the amount of glucose released was directly proportional to the amount of AMG used. The mixing time was increased and the elastic properties of the dough decreased when AMG was added. However, these impacts of AMG on dough properties were not as significant as those of sucrose addition. Addition of 0.75% AMG (flour basis) developed a sweet taste equivalent to that obtained by addition of 17% sucrose (flour basis).

The cellular structure of two products, an extruded breakfast cereal and a short dough biscuit, was characterized by two different X-ray micro computed tomographic systems. Acquisitions were made by a compact desktop system Skyscan 1174 (Bruker mu CT, Belgium) and at the European Synchrotron Radiation Facility (ESRF, beamline ID19, France) at different resolutions (voxel size of 6.5 mu m, 7.5 mu m, 16.2 mu m and 25.8 mu m). 3D images were processed for the density, the connectivity index and the granulometry of cells and cell walls. These experiments underlined the importance of the resolution for determination of quantitative measurements such as densities and thicknesses. The median width calculated for the cell walls distribution in the biscuit dropped from 141 to 50 mu m when the voxel size changed from 25.8 to 7.5 mu m. Images well showed that even though the food products had close values of porosity 0.6 and 0.7 for biscuit and extruded breakfast cereal respectively, their cellular structures were very different. The biscuit had small cells (median value of the distribution varied from 125 to 152 mu m, according to resolution) and larger cell walls (50-141 mu m) than the extrudate (32-109 mu m) which, on the contrary, exhibited very large cells (307-400 mu m). Beyond methodological issues, these differences could be clearly attributed to the differences of compositions and processes.

Injection of plasmid DNA encoding pseudorabies virus (PRV) glycoprotein into pig muscle has been shown to result in protective immunity against lethal infection. Here, pigs were vaccinated by a single coinjection of three plasmids encoding PRV glycoproteins gB, gC, and gD, with plasmid expressing porcine granulocytemacrophage colony-stimulating factor (GM-CSF) or porcine interferon-alpha (IFN-alpha). DNA immunization induced a primary T cell-mediated response characterized by low rates of IFN-gamma, interleukin-2 (IL-2), and IL4 mRNA in peripheral blood mononuclear cells (PBMC). Very low rates of PRV-specific IgG1 and the absence of IgG2 were obtained. Codelivery of plasmid expressing GM-CSF or IFN-alpha had no effect on cytokine mRNA expression or on B cell response. After a high virulent challenge, high levels of cytokine mRNA, mainly IFN-gamma, and high secondary antibody (Ab) response were induced in all DNA-vaccinated pigs. Codelivery of GMCSF gene significantly increased both Th immune response (i.e., IFN-gamma and IL-4 mRNA expression) and clinical protection but had no effect on secondary B immune response. Codelivery of IFN-alpha gene had no beneficial effect on secondary T and B cell immune responses.

The human immunodeficiency virus type 1 transmembrane envelope glycoprotein gp41 has been previously shown to activate the C1 complex of human complement through direct interaction with its C1q subunit. The major interaction site has been located within the gp41 immunodominant region (residues 590–620), and a synthetic peptide overlapping residues 601–613 of gp41 (sequence GIWGCSGKLICTT) was shown to inhibit binding of gp41 to C1q in vitro (Thielens, N.M., Bally, I.M., Ebenbichler, C_f., Dierich, M.P. & Arlaud, G.J. (1993) J. Immunol.151, 6583–6592). The ectodomain of gp41 (s-gp41) was secreted from the methylotrophic yeast Pichia pastoris and purified by immunoaffinity chromatography. Enzymatic deglycosylation of the recombinant s-gp41 was necessary to allow its in vitro interaction with C1q. A solid-phase competition assay was used to monitor the effect of mutant peptides derived from segment 601–613 of gp41 on the binding of deglycosylated s-gp41 to C1q. Whereas mutation of Ser606 had no effect, replacement of Ile602, Trp603, Lys608, Leu609 and Ile610 by Ala abolished the ability of the resulting peptides to inhibit binding of s-gp41 to C1q, suggesting that these residues participate in the interaction between gp41 and C1q. These findings are discussed in the light of a structural model of the immunodominant loop of gp41. It is proposed that the recognition of gp41 by C1q is driven by hydrophobic interactions, and that the sites of gp41 responsible for interaction with gp120 and C1q partly overlap.

International audience; Agglomerated food powders are made from native particles which are assembled to form grains. The present investigation seeks to contribute to a better understanding of the three-dimensional internal morphology of food agglomerates (i.e. different couscous grains made from durum wheat semolina under different agglomeration process conditions) by means of microscopic methods (size, compactness) and X-ray micro-computed tomography (XMT), to bring understanding of the process-structure relationships. The three-dimensional internal morphology of food agglomerates was evaluated by means of X-ray micro-computed tomography (XMT), using a tabletop system with a resolution of several micrometers. XMT was considered to evaluate the internal porosity (or void fraction) as well as the size and spatial distribution of pores inside the grains. Closed porosity values ranged between 0.005 and 0.011. Diameter of internal pores was found to range between 13 and 155 mu m which contribute to control mainly their end-properties. The experimental results were discussed to develop a better knowledge of the process-structure relationships for food agglomerates based on wheat powders, produced by wet agglomeration process. We demonstrated that the shearing conditions during the initial mixing stage significantly contribute to the internal structure characteristics of agglomerates. The cooking treatment is found to largely improve the mechanical strength of the agglomerates.

C1r is the modular serine protease responsible for autocatalytic activation of C1, the first component of the complement classical pathway. Its catalytic region is a noncovalent homodimer of two gamma-B monomers, each comprising two contiguous complement control protein (CCP) modules, IV and V [also known as short consensus repeats (SCRs)], a 15-residue intermediary segment, and the serine protease B domain. With a view to gain insight into domain-domain interactions within this region, fragment C1r (gamma-B)2, obtained by autolytic proteolysis of the active protease, was cross-linked with the water-soluble reagent 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. Cross-linked species gamma-B intra and gamma-B inter, containing intra- and intermonomer cross-links, respectively, were isolated and then fragmented by CNBr cleavage and trypsin digestion. N-Terminal sequence and mass spectrometry analyses of the resulting cross-linked peptides allowed us to identify one intramonomer cross-link between Lys426 of module V and the C-terminal Asp688 of the serine protease B domain and one intermonomer cross-link between the N-terminal Gly280 of fragment gamma and Glu493 of the B domain. Three-dimensional homology modeling of the CCP modules IV and V and of the B domain was also performed. The complementary information provided by chemical cross-linking and homology modeling studies was used to construct a three-dimensional model of the gamma-B monomer, in which module V interacts with the serine protease on the side opposite to both the active site and the Arg446-Ile447 activation site. Also, a tentative three-dimensional model of the (gamma-B)2 dimer was built, indicating a loose "head to tail" association of the monomers, with the active sites facing opposite directions toward the outside of the dimer. The latter model is compared with available low-resolution structural data, and its functional implications are discussed in terms of the conformational changes occurring during C1r activation.

The objective of this research was to evaluate the influence of static electric field (SEF) on the freezing of pork meat (pork tenderloin muscle) with respect to the size of ice crystal formulation. The results showed that by increasing the strength of the static electric field, the degree of supercooling was reduced. The measured degree of supercooling varied from 3.93 ± 1.3 °C to 1.92 ± 1.45 °C for the control and the frozen sample under 12 kV SEF, respectively. Meat microstructure was investigated after Carnoy fixation of the frozen tissues. The overall relative surface of the ice crystals was unchanged. The average equivalent circular diameter of the ice crystals was significantly reduced with increasing SEF; values from 32.79 ± 4.04 μm for the control to 14.55 ± 8.20 μm for the sample frozen at the maximum magnitude electric field which was tested were observed respectively. These findings demonstrate clearly the advantage of freezing under SEF which appears as a promising and innovative freezing process for food systems. Industrial relevance The reduction of freeze damage exerted to any tissue undergoing freezing remains a challenge. The mechanical and biochemical stress caused by the ice crystals to the cellular membranes results in irreversible tissue damage. Freezing under static electric field (SEF) has been identified as a possible means to reduce the size of ice crystals during freezing of biological tissues. In the present study SEF was applied during freezing of pork meat. Our results indicate that the size of the formed ice crystals was significantly reduced under SEF freezing leading to a lower damage on the microstructure of meat. This paper describes an innovative freezing process that could be used in order for higher quality frozen products to be produced.

A prolyl endopeptidase was purified from Flavobacterium meningosepticum. It was digested with trypsin. Two oligonucleotides, based on tryptic peptide sequences and used in PCR experiments, amplified a 300-base pair (bp) fragment. A 2.4-kilobase EcoRI fragment that hybridized to the 300-bp probe was cloned in lambda ZAP and sequenced from both strands. It contains a reading frame of 2115 bp, encoding the complete protein sequence of 705 amino acids. Ion-spray mass spectrometry experiments demonstrated the presence of an NH2-terminal signal peptide: the periplasmic mature protease is 685 residues in length for a molecular mass of 76784 Da. The prolyl endopeptidase showed no general sequence homology with known protein sequences except with that of porcine brain prolyl endopeptidase. In order to identify the active-site serine, the prolyl endopeptidase was labeled with [3H]diisopropyl fluorophosphate. One labeled peptide was purified and sequenced. The active-site serine was located in position 536 within the sequence GRSNGG. This sequence is different from the active-site sequence of the trypsin (GDSGGP) and subtilisin (GTSMAS) families.

International audience; A simple imaging system has been developed for acquiring multivariate images in order to characterise the heterogeneity of food materials. The objective of the present work is, first, to demonstrate the capability of this acquisition system to discriminate food products of different natures. Secondly, our goal is to apply Partial Least Squares regression on these multivariate images and to evaluate the interest of various strategies of classification. A data set containing 24 images (702 X 524) acquired at different wavelengths for four food products is analysed. After the establishment of the PLS2 models employed for predicting the indicator variables, four strategies of classification of observations are tested. The first classification is done by selecting the largest component of the indicator variables. The others are based on the measurement of distances to the barycentres of the qualitative groups. Distances calculated can be either Euclidian distances or Mahalonobis ! distances. Except the strategy based on the Euclidian distance on scores, the strategies are rather equivalent, with a slight advantage to the Euclidian distance on predicted indicators. Another possibility addressed by the use of linear discriminant analysis (LDA) on multivariate images is to represent the qualitative groups as artificial images. The largest confusion appears between both cereal products while others are well classified.

International audience; A better understanding of cell-mediated immune responses to classical swine fever virus (CSFV) is essential for the future development of improved vaccines. We analyzed the generation of cell-mediated and humoral immune responses in d/d histocompatible pigs following CSFV infection or vaccination. Viral infection induced high T cell responses with high primary and secondary CTL activity correlated with high IFN-$\gamma$ production, whereas vaccination with a live vaccine followed by infection mainly induced neutralizing antibody but low cell-mediated responses. Moreover, high IgG1 response was associated with high IFN-g response following infection whereas a weak IFN-$\gamma$ response was related to a good IgG2 response but a low IgG1 production. These data could reflect Th1/Th2-like balance of immune responses depending upon immunization protocols, which has not yet been described in the pig. T-cell responses to CSFV were evidenced by CSFV-specific CD25 upregulation on CD4$^{-}$CD8$^{+}$, but not on CD4$^{+}$CD8$^{-}$ cells, which further illustrated the importance of CTL responses after infection. Our results indicated that generation of cell-mediated immune responses was much higher following intranasal/oral CSFV infection than after intramuscular vaccination, which implies that the capacity of new CSFV vaccines to induce higher T-cell responses should be considered.

Short dough baking was performed in a pilot-scale oven under various conditions allowing macroscopic changes to be studied in relation to physical and biochemical modifications during the baking process. The influence of baking parameters (temperature, humidity and air velocity) on macroscopic and microscopic changes was investigated, together with variations (temperature and moisture content, heating and drying rates) in product variables. The major changes observed during biscuit baking were (i) development of a partially open porous structure associated with reduction in density, (ii) drying, and (iii) surface colouring. Structural changes were due to water vaporisation and gas bubbles produced by the decomposition of the chemical leavening agents used. Expansion stopped because of the depletion of chemical leavening agents and percolation of water vapour at appropriate temperatures. The setting of biscuit structure was not related to thermal aggregation of proteins (which began at 85 °C) or to limited starch granule damage at temperatures below 100 °C. Setting apparently occurred during the cooling period when molten sugars undergo a glass transition. Surface colouring of the biscuit and a subsequent decrease in lightness were correlated with reduced sugar consumption in Maillard reactions.

The influence of selected pregelatinized starches on staling of pound cake has been investigated considering wheat and maize pregelatinized starches as flour substitutes. Two baking systems were considered to assess staling: a miniaturized baking system providing degassed baked batter and a conventional oven providing real products. Texture profile analysis, compression, and rupture tests were used to follow texture evolution during storage. Results confirmed the positive effect of partial substitution by pregelatinized starches in microcakes on retarding staling, while the denser structure of pregelatinized starch cakes prevented the same positive impact on texture and staling.

Previous studies based on the use of serum as a source of C have shown that fibrils of β-amyloid peptides that accumulate in the brain of patients with Alzheimer’s disease have the ability to bind C1q and activate the classical C pathway. The objective of the present work was to test the ability of fibrils of peptide Aβ1–42 to trigger direct activation of the C1 complex and to carry out further investigations on the site(s) of C1q involved in the interaction with Aβ1–42. Using C1 reconstituted from purified C1q, C1r, and C1s, it was shown that Aβ1–42 fibrils trigger direct C1 activation both in the absence of C1 inhibitor and at C1 inhibitor:C1 ratios up to 8:0, i.e., under conditions consistent with the physiological context in serum. The truncated peptide Aβ12–42 and the double mutant (D7N, E11Q) of Aβ1–42 did not yield C1 activation, providing further evidence that the C1 binding site of β-amyloid fibrils is located in the acidic N-terminal 1–11 region of the Aβ1–42 peptide. Binding studies performed using a solid phase assay provided strong evidence that C1q interacts with Aβ1–42 fibrils through its C-terminal globular regions. In contrast to previous studies based on a different experimental design, no significant involvement of the C1q collagen-like domain was detected. These findings were confirmed by additional experiments based on C1 activation and C4 consumption assays. These observations provide direct evidence of the ability of β-amyloid fibrils to trigger activation of the classical C pathway and further support the hypothesis that C activation may be a component of the pathogenesis of Alzheimer’s disease.

Nineteen dough systems were made of a combination of two to nine of the following ingredients: flour, water, fats (coconut and/or palm oils), sugars (sucrose, invert) and chemical leaveners (ammonium bicarbonate, sodium bicarbonate, citric acid and sodium acid pyrophosphate). Their thermal behaviour was studied over a large temperature scale (20 °C to 160 °C). Thermal analysis of baking by three different methods (DSC, DMTA and TGA) at the same heating rate (3 °C/min) provided information about phase transitions, volume and mass changes of doughs during heating. Temperature ranges over which all ingredients reacted were identified. Melting transitions of fats occurred between 10 °C and 50 °C. Sugars increase temperatures of starch transitions. Chemical leaveners decrease rise temperature, whereas fats and sugars have a delaying effect on their action. The texture of biscuits results from interactions between ingredients; complete dough cannot thus be considered as merely a simple addition of all components.

Meprin (endopeptidase-24.18; EC 3.4.24.18) is a multisubunit zinc-metallopeptidase found in the brush-border membranes of rodent kidney and human intestine. The alpha and beta subunits of meprin are disulphide-linked to form either soluble alpha 2 homodimers or membrane-associated alpha/beta heterodimers. The aim of the present study was to identify the cysteine residue(s) implicated in the formation of alpha 2 and alpha/beta dimers and to investigate the effects of dimerization on intracellular transport and processing of the alpha subunit. Three cysteine residue candidates for the formation of disulphide bonds in the alpha subunit were selected by hydrophobic cluster analysis. These residues, located at positions 309, 560 and 562, were mutated to serine residues. When the resulting alpha subunit mutants were expressed alone in COS-1 cells, the alpha C560S and alpha C562S mutants were found to be secreted as alpha 2 homodimers whereas the alpha C309S mutant was found as monomers in the culture medium. In double-transfection experiments with the wild-type beta subunit, the alpha C560S and alpha C562S mutants behaved exactly as the wild-type alpha subunit and formed membrane-bound alpha/beta heterodimers. In contrast, the alpha C309S mutant was not retained at the cell surface but rather secreted as monomers in the culture medium, as was found in the simple transfection experiment. These results show that, despite the normal expression level and folding of the protein in a transport-competent from, the alpha C309S mutant is unable to form alpha 2 homodimers or alpha/beta heterodimers. This suggests that Cys309 is the unique residue of the alpha subunit implicated in the alpha 2 and alpha/beta dimerizations. Hydrophobic cluster analysis of the alpha and beta subunit sequences predicts that Cys309 is similar to Cys306 of the beta subunit. We mutated the latter residue to a serine and expressed the beta C306S mutant and the wild-type alpha subunit in the same COS-1 cells. No beta 2 or alpha/beta dimers were observed on immunoblotting, showing that Cys306 of the beta subunit is required for the formation of intermolecular disulphide bonds both in beta 2 homodimers and in alpha/beta heterodimers. Taken together, these results suggest that the alpha/beta heterodimeric form of meprin is held together by a single disulphide bond linking Cys309 in the alpha subunit to Cys306 in the beta subunit.

The movement of moisture in the porous network of certain materials is very often at the origin of phenomena prejudicial to the durability of the constructions of the civil engineering. This is particularly the case for the drying of wood, which creates cracks and delaminations at bonding interfaces, and for concrete in situations of fire where the movement of moisture can induce irreversible disorders (chipping). The use of predictive models of structural ruin therefore requires the simulation of the moisture movement within the materials. These mass and heat transfer models are sophisticated and need to be confronted with measurements in order to be validated. Few experimental techniques exist to measure moisture movements or gradients in porous networks, especially in transient conditions (drying, fire). Existing techniques are often expensive and impose severe conditions of safety for the researchers. The objective of the thesis is therefore to develop a device for measuring gradients of moisture based on Terahertz imagery. This is a comparatively inexpensive measuring technique and makes it possible to carry out transient measurements. An existing experimental bench will therefore be adapted to the measurement of the moisture field on wood specimens under variable water-moisture conditions and on concrete specimens in a heating situation. The results will constitute a database useful for understanding the phenomena of degradation of materials and will be directly usable as a validation tool for calculation models.; Le mouvement d’humidité dans le réseau poreux de certains matériaux est très souvent à l’origine de phénomènes préjudiciables pour la durabilité des constructions du génie civil. C’est en particulier le cas pour le séchage du bois, générateur de fissures et de délaminations aux interfaces de collage, et pour le béton en situation d’incendie où le mouvement d’humidité peut induire des désordres irréversibles (écaillage). Le recours à des modèles prédictifs de ruine des structures nécessite donc la simulation du mouvement d’humidité au sein des matériaux. Ces modèles de transfert de masse et de chaleur sont sophistiqués et nécessitent d’être confrontés à des mesures afin d’être validés. Peu de techniques expérimentales existent pour mesurer les mouvements ou gradients d’humidité dans les réseaux poreux, en particulier en régime transitoire (séchage, incendie). Les techniques existantes sont de plus généralement coûteuses et imposent des conditions sévères de sécurité pour les chercheurs. L’objectif de la thèse est donc de mettre au point un dispositif de mesure de gradients d’humidité basé sur l’imagerie Térahertz. Il s’agit d’une technique de mesure relativement peu onéreuse et permettant de réaliser des mesures en régime transitoire. Un banc expérimental existant sera donc adapté à la mesure du champ d’humidité sur éprouvettes de bois en conditions thermo-hydriques variables, et sur éprouvettes de béton en situation de chauffage. Les résultats constitueront une base de données utile à la compréhension des phénomènes de dégradation des matériaux et seront directement utilisables comme outil de validation de modèles de calcul.