Camille Loupiac

University of Burgundy | UB · AgroSup Dijon

The root system plays an essential role in the development and physiology of the plant, as well as in its response to various stresses. However, it is often insufficiently studied, mainly because it is difficult to visualize. For grapevine, a plant of major economic interest, there is a growing need to study the root system, in particular to assess...

To probe intermediate states during unfolding and oligomerization of proteins remains a major challenge. High pressure (HP) is a powerful tool for studying these problems, revealing subtle structural changes in proteins not accessible by other means of denaturation. Bovine β-lactoglobulin (BLG), the main whey protein, has a strong propensity to bin...

To probe intermediate states during unfolding and oligomerization of proteins remains a major challenge. High pressure (HP) is a powerful tool for studying these problems, revealing subtle structural changes in proteins not accessible by other means of denaturation. Bovine β-lactoglobulin (BLG), the main whey protein, has a strong propensity to bin...

We show here how the structure of polygalacturonate (polyGalA) hydrogels cross-linked by Ca2+ cations via external gelation controls the loading and the release rate of betalactoglobulin (BLG), a globular protein. Hydrogels prepared from a polyGalA/BLG solution are found similar to those obtained from a polyGalA solution in our previous study (Mair...

THE INDUSTRIAL CHALLENGE: Increasing the shelf life of bread products is of great importance for Lantmännen and bread manufacturers in general. Increased understanding of water distribution and movement in bread during baking and storage can potentially be used to increase the shelf life and prolong the fresh texture of bread products. We acknowle...

High hydrostatic pressure (HHP) treatments are trending as “green” stabilization and extraction process. The extraction of B-phycoerythrin from microalgae is getting more and more interest due to its numerous potentialities in foods, cosmetics and medicine. Thus, the effects of high pressure on the structural characteristics of B-phycoerythrin extr...

During the extraction processes of B-phycoerythrin from P. cruentum, the possibility of the occurrence of extraction-inhibiting B-phycoerythrin/exopolysaccharide (EPS) complexes was highlighted. The use of confocal laser scanning microscopy allowed the observation of the cells including their sheath and their chloroplast, the bound EPS matrix, and...

We report on a high pressure (HP) cell designed for the determination of the structure of molecular solutions by small-angle neutron scattering (SANS). The HP cell is fitted up with two thick metallic windows that make the device very resistant under hydrostatic pressures up to 600 MPa (or 6 kbar). The metallic windows are removable, offering the p...

The aim of the study was to extract B-phycoerythrin from Porphyridium cruentum while preserving its structure. The high hydrostatic pressure treatments were chosen as extraction technology. Different methods have been used to observe the effects of the treatment: spectrophotometry and confocal laser scanning microscopy followed by image processing...

Effect of high pressure (HP) treatment on the antimicrobial properties and the structure of nisin was evaluated. Nisin solutions at pH 2.8 or 6.1 were treated by HP at 500 MPa – 10 min – 20 °C and their antimicrobial potency was determined. It appeared that HP clearly impacted the antimicrobial activity of nisin, with respective activity loss of 22...

Neutron imaging and tomography allow observing the structure of large objects (from few to hundred centimeters) at a resolution around 100 μm. This nondestructive method is based on the detection of the transmission of a neutron beam through an object in 2D (imaging) or 3D after rotating the sample (tomography). The components of the object attenua...

The powerful of neutron scattering techniques to characterize structure and dynamics of milk proteins is illustrated. Small angle neutron scattering and reflectivity are used to determine the structure and the interactions between milk proteins in solution, during gelation processes, or the protein structure at different interfaces. Experiments per...

Neutron imaging was used to follow the impact of cooking on beef meat. During online cooking, the cartography realised on image collected shows neutron attenuation per zone. Some data points were taken on the edge to highlight higher attenuation variations because of “microscopic” shrinkage of the meat at 70 °C. Some others points were taken in the...

A second cold neutron imaging station has been open to users at the Laboratoire Léon Brillouin. The station is designed for high resolution neutron imaging and tomography. The typical field of view is 100x100 mm2 with a spatial resolution of 100μm. Betterspatial resolutions (∼50μm) can be achieved when reducing the field of view down to 30x30mm2. T...

Neutron scattering and neutron imaging are powerful techniques for studying the structure of objects without damage, which is an essential prerequisite for investigations in Cultural Heritage domain, particularly in Archaeology. The deep penetration of neutrons in most materials allows for the study of relatively large objects. The contrast between...

In this paper, we compare the interactions between low methoxy pectin (LMP) and either Ca2+ or Zn2+ in semi-dilute solutions. Intrinsic viscosity and turbidity measurements reveal that pectin-calcium solutions are more viscous, but yet less turbid, than pectin-zinc ones. To get a molecular understanding on the origin of this rather unexpected behav...

In this work, the adsorption of a small globular protein (betalactoglobulin, BLG), on a natural montmorillonite clay (Mt) was investigated in acidic buffer (pH=3). The combination of different characterization techniques such as zetametry, X-ray diffraction, transmission electronic microscopy, fluorescence and solid state nuclear magnetic resonance...

Open Food System is an industrial innovation project having as goal the development of “smart” domestic appliances, which can pilot cooking process of meat and fish without any human intervention. My Ph.D research belongs to that huge project with the purpose to follow the evolution of cooking process at molecular scale, describing biochemical reac...

Open Food System is an industrial innovation project having as goal the development of “smart” domestic appliances, which can pilot cooking process of meat and fish without any human intervention. My Ph.D research belongs to that huge project with the purpose to follow the evolution of cooking process at molecular scale, describing biochemical reac...

If protein structure and function changes upon adsorption are well documented, modification of adsorbed protein dynamics remains a blind spot, despite its importance in biological processes. The adsorption of metmyoglobin on a silica surface was studied by isotherm measurements, microcalorimetry, circular dichroïsm and UV-visible spectroscopy to de...

Methods: Combining small-angle X-ray and neutron scattering measurements with inelastic neutron scattering experiments, we investigated the impact of high hydrostatic pressure on the structure and dynamics of β-lactoglobulin (βLG) in aqueous solution. Background: βLG is a relatively small protein, which is predominantly dimeric in physiological...

Protein powders from Eisenia foetida were prepared using different drying processes and fractionation. Differential scanning calorimetry was used to show that heat denaturation occurred during the drying process above 42˚C. Protein solubility was also studied. The addition of dissociating reagents allowed concluding that solubility was decreased du...

Any protein ingested intentionally or non-intentionally can be considered as a food protein. The scope of food protein chemistry covers agricultural production, processing, packaging, storage, distribution, retail and protein function as ingredients. Protein quality is an important consideration to the consumer as is allergy and other adverse react...

Contributions sur l'utilisation des hautes pressions dans les grands domaines de recherches. Les auteurs offrent un bilan décennal du domaine scientifique dont ils sont les principaux acteurs et montrent l'évolution des thèmes de recherches, les méthodes, les questions, les récentes réussites et les nouveaux enjeux propres à chaque discipline.

pour le champs 'auteurs', les Directeurs de publications apparaissent en premier puis le Directeur de collection.

This work was undertaken to investigate thermal and dynamic transitions observed in the temperature range close to the bulk ice melting temperature in sucrose solutions. Measurements of thermal (differential calorimetry) and dynamic (neutron scattering) properties were compared in order to give a physical interpretation of the thermal transitions o...

The state of water in foodstuffs is a guiding principle in food design, and the equilibrium concept of water activity (Aw) is ubiquitous. It is regarded as a primary variable or “hurdle” in preservation technology, and a key variable influencing chemical reaction during storage. However, the amount of water in any system differs as function of wate...

Tethered bilayer lipid membranes have been used as a model system to mimic the interactions between the whey protein β-lactoglobulin and a lipid interface. The approach allowed for a detailed study of the lipid-protein interactions, the results being of possible importance in food and cosmetic applications. For such applications, lipid-protein inte...

Protein-lipid interactions play an important role in a variety of fields, for example in pharmaceutical research, biosensing, or food science. However, the underlying fundamental processes that govern the interplay of lipids and proteins are often very complex and are therefore studied using model systems. Here, Langmuir monolayers were used to pro...

Iron incorporated into food systems induces oxidation and precipitation. The consequences are reduced bioavailability and a functional modification of other food components such as proteins. The iron-chelates such as ferrous bisglycinate represent a possibility to avoid side effects, since the iron is protected. The aim of this study is to investig...

Calcium and zinc pectinate gels were prepared using a method which allowed calcium or zinc to diffuse from the cross-linking solution through a dialysis membrane to form a gel with amidated low-methoxyl pectin. The gel thus obtained was then dried, and the film structure was studied using FTIR spectroscopy as a function of the cation content (0%, 5...

We used small-angle neutron scattering to study the effects of the high hydrostatic pressure on the structure of beta-lactoglobulin. Experiments were carried out at pH 7 on the dimeric form of the protein in a pressure range going from 50 MPa to 300 MPa. These measurements allow the protein size and the interactions between macromolecules to be stu...

URL: http://www-spht.cea.fr/articles/S03/040 Org.: Vacher R. Oral Presentation

Small-angle neutron scattering experiments were performed on horse azidometmyoglobin (MbN3) at pressures up to 300 MPa. Other spectroscopic techniques have shown that a reorganization of the secondary structure and of the active site occur in this pressure range. The present measurements, performed using various concentrations of MbN3, show that th...

13C NMR signals of 13CO free and bound to hemoglobin (Hb13CO) were investigated at 9.4 T. Existence of 13CO exchange between α and β hemoglobin irons was proven by 13C NMR temperature line splitting and by the shift of the 13CO NMR signal, after mixing α13CO with deliganded β or β13CO with deliganded α. 13C NMR bandwidth of 13CO bound to hemoglobin...

13Carbon monoxide (CO), when bound to hemoglobin, yields (13)C NMR resonances (CO-Fe resonances). 100% CO liganded tetrameric hemoglobin ((13)C-labelled CO) was prepared for (13)C-NMR observation. The information about exchange kinetics between the four subunits (2alpha and 2B), were derived by changing the temperature (in the range 275-313K) and t...

Transient heme–protein interactions upon passing from ligated to deligated carp hemoglobin were observed through time-resolved optical spectra following nanosecond CO photodissociation. The spectral evolution of the heme, in the nanosecond and microsecond time ranges, shows a protein conformational relaxation and the absence of a geminate CO recomb...

During the last 50 years, our knowledge of the properties and roles of water in foods has progressed very significantly; at the beginning of this period, the emphasis was on the binding of water to other constituents, which was supposed to impart to it special properties, different from those of bulk water. These concepts of free and bound water we...