Anne Desrumaux

French National Centre for Scientific Research, Lutetia Parisorum, Île-de-France, France

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Publications (12)13.89 Total impact

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    ABSTRACT: A better control of the foaming process is important for food industry, as the structure of the liquid/gas mixture is a key parameter for the end-used properties of foams. The main concern of this study is to present a methodology applicable to the parametric study of the foaming process that can help either to optimize the operating conditions or to adapt the formulation. We focused on the valorization of egg white proteins (EWPs). The method allows studying the effect of the process parameters on the foam structure and the effect of the thermal pretreatment of the EWP in the dry state on the rheology and the stability of foams. The foaming is achieved with a SMX10 static mixer, which allows the production of controlled structure foams. It is, therefore, possible to investigate the dependence of foam properties by comparing foams with the same alveolar structure in relation with their formulation. © 2012 American Institute of Chemical Engineers AIChE J, 59: 132–145, 2013
    AIChE Journal 01/2013; 59(1). · 2.58 Impact Factor
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    ABSTRACT: The properties of foams processed with reconstituted egg white were investigated as a function of the denaturation undergone by the proteins during the pasteurization stage in dry state. Various time–temperature tables were applied on the original egg white powder, ranging from 1 to 7 days, and from 60 to 80 °C. Differential Scanning Calorimetry was used to determine the denaturation degree of each EWP induced by the dry heat treatment. The rheological properties of the interface, using the drop tensiometer method, were shown to be significantly affected by the denaturation and to be a relevant parameter for foamability, stability and foam texture. The bulk properties of the foams were interrelated with interfacial properties by using principal component analysis (PCA) and cluster analysis (HCA). The resulting classification of the heat treatments reveals that mild treatment offers a good compromise between the heating cost and the functional properties of the foams.
    LWT - Food Science and Technology. 01/2009; 42(2):496-503.
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    ABSTRACT: The objective of the present work was to investigate the effect of the heating process on the structural and rheological properties of whey protein isolate/cross-linked waxy maize starch (WPI/CWMS) blends depending upon the concentration and the starch/whey protein ratio. Starch concentration ranged from 3 to 4% (w/w) and the protein content was of 0.5, 1 and 1.5% (w/w). The blend (pH 7, 100mM ionic strength) was heated using a jacketed vessel at two pasting temperatures: 90 and 110°C. The particle size distribution of the WPI suspension (1.5%) displayed three distinct classes of aggregates (0.3, 65 and 220μm), whereas the size of swollen starch granules varied from 48 to 56μm according to the pasting temperature. When the two components were mixed together, the peak attributed to swollen starch granules was attenuated and broadened towards higher values (up to 88μm) due to protein aggregates (260–410μm). This effect was more pronounced as the protein concentration increased. When compared to starch alone, the rheology of the mixed system was dramatically modified for the flow behaviour as well as for the viscoelastic properties which changed from a solid-like (3–4% starch) to a liquid-like behaviour (3–4% starch/1.5% protein). Microscopic observations showed aggregated proteins located in the continuous phase and swollen starch granules as the dispersed phase. Protein aggregates were of different sizes, part of them appeared adsorbed onto swollen starch granules while another part was unevenly distributed in the continuous phase, yielding discontinuous network which could explain the peculiar viscoelastic behaviour of such suspensions.
    Food Hydrocolloids - FOOD HYDROCOLLOID. 01/2009; 23(7):1678-1686.
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    J. Floury, A. Desrumaux, J. Legrand
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    ABSTRACT: An ultra high-pressure homogenizer (20 to 350 MPa) was used to realize fine food emulsions stabilized by soy proteins. The first aim of the work was to understand how dynamic high-pressure processing affects soybean globulin conformation. Then, the effect of homogenizing pressure on the emulsions structure and rheology was investigated. High-pressure homogenization caused denaturation of proteins due to strong mechanical forces and high temperatures encountered in the valve. Droplet sizes of emulsions were greatly reduced with high-pressure homogenization and Newtonian liquid emulsions were converted into shear-thinning emulsion gels by homogenization at pressures above 250 MPa. Hydrophobic interactions between proteins were supposed to cause the gel-like network structure of emulsions.
    Journal of Food Science 07/2006; 67(9):3388 - 3395. · 1.78 Impact Factor
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    ABSTRACT: An ultra high-pressure homogenizer was used to treat whey protein isolate solutions (3%, w/w). The treated solutions (up to 300 MPa) were characterised for both physico-chemical properties (particle size distribution, surface hydrophobicity and structural conformation) and functional properties (solubility, foaming stability and interfacial rheology). Dynamic high-pressure treatment did not affect the conformation of the proteins (determined by micro-calorimetry, size-exclusion chromatography and electrophoretic technique). This treatment dissociated large protein aggregates leading to unmasking of the buried hydrophobic groups without affecting protein solubility. Interactions may then occur between these groups that enhance the viscoelasticity of air-water interfaces (assessed by drop tensiometry) and improve foam stability (evaluated by sparging method). Dynamic high-pressure-treated whey proteins showed better foaming and stabilising properties.
    International Dairy Journal. 01/2006;
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    ABSTRACT: In order to modify their state of aggregation, the seric protein solutions (pH = 7) at different concentrations (3, 5 and 15 g/L) and different ionic forces (3 and 100 mM) have been treated in an APV plate heat exchanger at 80, 100 and 120 °C, after that in a high pressure homogenizer at 1000, 2000 and 3000 bars. The dimensional range of the obtained aggregates has been characterized through laser granulometry and light dynamic diffusion. In order to establish the modification of functional properties of the seric protein solutions, emulsions and foams have been prepared starting from these solutions treated as mentioned before. The results showed that the thermomechanical treatments that have been used allowed the formation of aggregates whose dimensions where more important than the increase in the ionic strength of the solution. The properties of the emulsions obtained with treated protein solutions are similar, whatever the starting concentration or type of applied treatment was. The treated protein solutions exhibited an improved foaming capacity.
    01/2006; VII:1582-540.
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    Juliane Floury, Jack Legrand, Anne Desrumaux
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    ABSTRACT: Calculation of the flow pattern in a new small homogenising valve design (Stansted, U.K.), able to reach operating pressure as high as , was investigated in the first part of this paper using a Computational Fluid Dynamics method. Numerical simulation results are used in the present paper to better understand the emulsification process in the Stansted high-pressure homogeniser.Deformation of drops is supposed to occur in the intense elongational flow caused by the restriction between the piston and the seat of the valve. Deformation may be mainly followed by drop disruption in the narrow valve gap. Break-up probably also occurred in the highly turbulent region, located just at the exit of the gap, and underlined by the numerical investigation. Cavitation and the rate of recoalescence, first assumed from numerical results, are determined thank to experimental methods. Intensities of both phenomena strongly increase with homogenising pressure. Final droplet size of model oil-in-water emulsions is then the result of equilibrium between droplet break-up and recoalescence, which strongly depends on operating pressure.
    Chemical Engineering Science. 01/2004;
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    ABSTRACT: High-pressure homogenisation is a key unit operation used to disrupt fat globules or cells containing intracellular bioproducts (AIChE J. 43(4) (1997) 1100). Modelling and optimisation of a small homogenising unit are often restrained by a lack of information on the flow conditions within the homogeniser valve. A numerical investigation of the flow within such a new homogenising valve, capable to reach pressure as high as 350MPa (Stansted Fluid Power Ltd, UK) is presented. Results are obtained using the finite-volume technique and a RNG k–ε turbulence model with low Reynolds number near wall treatment conditions. An experimental measurement of the size of the valve gap is presented in order to validate mathematical relations that give valve gap sizes versus homogenising pressure. The modelling results give detailed information on the mechanical stresses and the high shear rates in small disruption valves, and also reveal other phenomena that could not be easily determined experimentally.
    Chemical Engineering Science - CHEM ENG SCI. 01/2004; 59(4):843-853.
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    ABSTRACT: A new high pressure homogeniser going up to 350 MPa was used to produce fine emulsions stabilised by methylcellulose for food applications. The objective of this study was to evaluate the effect of homogenising pressure on emulsifying and stabilising properties of methylcellulose, a food macromolecule extensively used as stabiliser in emulsions. Oil droplet size distributions of the emulsions were measured by laser-light scattering; rheological properties were characterised with a coaxial cylinder rheometer; and stability was evaluated by heating of the emulsions. Influence of homogenising pressure on interfacial properties (adsorption kinetics, interfacial tension and rheological behaviour) of the polymer was also studied at different pressure treatments. The results showed significant modifications in the structure and the texture of emulsions with increasing homogenising pressure. Homogenised methylcellulose solutions showed weaker thickening and stabilising properties compared to the one of the native methylcellulose.
    Journal of Food Engineering 01/2003; · 2.28 Impact Factor
  • Anne Desrumaux, Julie Marcand
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    ABSTRACT: A new ultra-high-pressure homogenizer was used to make very fine oil in water emulsions. The effect of pressures up to 350 MPa on sunflower oil (20%) in water emulsions was studied. The emulsifier used was whey protein concentrate (1.5%). The properties of the emulsions were characterized by laser light scattering (droplet size distribution) and coaxial cylinders rheometry (rheological behaviour). The protein adsorption fraction was obtained by a spectrophotometric method using bicinchoninic acid reagent.Significant modifications in the structure and the texture of the emulsions were observed as the pressure increased. No change was revealed by polyacrylamide gel electrophoresis of the whey protein within the pressure range studied. Microdifferential scanning calorimetry scans indicated that the changes of the structural and textural properties may be because of changes in the protein conformation.
    International Journal of Food Science & Technology 03/2002; 37(3):263 - 269. · 1.24 Impact Factor
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    ABSTRACT: Initially developed for the dairy industry, the very high pressure homogenisation (>100 MPa) is now also applied in the pharmaceutical sector and in biotechnology (breaking cells for biomass extraction). The use of this technology to make fine food emulsions and to modify functional properties of macromolecules seems to be promising. Thus the objective of this study was to understand the effect of homogenisation forces on the mechanical degradation of a model polymer extensively used in food, cosmetic and pharmaceutical preparations: the methylcellulose. Degradation of the polymer was studied in a pressure range in the homogenising valve from 20 to 350 MPa. It was observed that as the pressure imposed by the homogeniser increased, the intrinsic viscosity decreased. Intrinsic viscosity decrease was correlated to apparent changes in the average molecular weight of the polymers obtained by size exclusion chromatography coupled on-line with multi-angle laser light scattering and refractive index detection (SEC/MALLS/RI). The strong elongational flow encountered by the polymer at the entrance of the valve of the high pressure homogeniser device may bring sufficient energy to disrupt covalent bonds. Consequently, as shown by flow behaviour the thickening properties of this polymer were also reduced.
    Food Hydrocolloids 01/2002; · 3.49 Impact Factor
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    ABSTRACT: A new ultra high-pressure homogenizer (STANSTED, UK) going up to 350 MPa, was used to realize very fine oil-in-water emulsions. The effect of homogenizing pressure (from 20 to 300 MPa) was studied on model emulsions stabilized by whey proteins. Oil droplet size distributions were measured by laser-light scattering. Rheological properties were characterized with a coaxial cylinder rheometer. The results showed significant modifications in the structure and the texture of emulsions with increasing pressure. Ultra high-pressure homogenizing conditions brought about the high oil content emulsions (>40% w.w.b) from shear-thinning behaviors (at 20 MPa) to Newtonian behaviors (at 300 MPa). Droplet size was reduced with increasing pressure. However, the flow curves could not be fully explained by the droplet size distributions.
    Innovative Food Science & Emerging Technologies 01/2000; · 2.53 Impact Factor