WO1995012122A1 - Method and equipment for determining the stability of an emulsion - Google Patents

Method and equipment for determining the stability of an emulsion Download PDF

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Publication number
WO1995012122A1
WO1995012122A1 PCT/FR1994/001237 FR9401237W WO9512122A1 WO 1995012122 A1 WO1995012122 A1 WO 1995012122A1 FR 9401237 W FR9401237 W FR 9401237W WO 9512122 A1 WO9512122 A1 WO 9512122A1
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Prior art keywords
conductivity
emulsion
height
column
phase
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PCT/FR1994/001237
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French (fr)
Inventor
William Loisel
Yves Popineau
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Institut National De La Recherche Agronomique
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Application filed by Institut National De La Recherche Agronomique filed Critical Institut National De La Recherche Agronomique
Priority to EP94931627A priority Critical patent/EP0725931A1/en
Publication of WO1995012122A1 publication Critical patent/WO1995012122A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/06—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid
    • G01N27/07—Construction of measuring vessels; Electrodes therefor

Definitions

  • the present invention relates to a method and equipment for characterizing the stability of an emulsion.
  • knowing the capacity of a product to facilitate and / or stabilize an emulsion is of capital importance in order to obtain the characteristics of stability, texture, appearance, duration of conservation and / or taste, desired by consumers.
  • the first step consists in producing an emulsion by mixing two immiscible primary phases, generally one aqueous and the other organic, in particular lipidic; one of these phases is constant, the other constitutes the product to be tested or contains this product in suspension or in solution.
  • the technique then consists in monitoring the separation of these two phases over time and in qualifying this separation as best as possible.
  • a first object of the invention is to propose a method and a material for characterizing the stability of an emulsion which use a simple and reliable technology.
  • Another object of the invention is to propose a process and a material very easy to implement, which very precisely and reproducibly account for the emulsifying or emulsifying power.
  • Another object of the invention is to propose a standardized method for measuring the emulsifying properties which, in conjunction with the equipment used, makes it possible to simultaneously study a series of samples.
  • the method according to the invention allows the characterization of the stability of an emulsion placed in an analysis cell.
  • This emulsion can be produced inside the cell or outside; it is carried out by mixing two immiscible primary phases, the continuous phase being conductive and the dispersed phase being non-conductive.
  • This method is characterized by the fact that it consists in measuring the evolution of the conductivity within said emulsion, this over the cell height which corresponds to the volume and the location of one of said primary phases.
  • the conductivity evolution is measured over a well-determined height and level of the cell; this height and this level correspond to the location of either the conductive phase or the non-conductive phase when said phases are separated, that is to say when they are superimposed in the cell.
  • the conductive phase consists of an ionized aqueous phase and the non-conductive phase is a lipid phase; measurement of the conductivity over the entire height of one of the phases in the cell analysis determines the concentration of water in oil or oil in water, as appropriate.
  • the variation in conductivity of the volume of aqueous or lipid phase which is produced by the incorporation of oil in water or of water in oil reflects the destabilization of the emulsion.
  • the equipment for the implementation of this process consists of a column-shaped analysis cell, closed by a bottom, at its lower part.
  • This column includes conductivity measurement electrodes, connected to a conductivity meter; these electrodes extend over part of the height of said column, to measure the conductivity of the sample analyzed over this entire height.
  • the conductivity measuring electrodes can extend from the bottom of the column, to measure the conductivity over the column height which corresponds to the height and volume of the lower primary phase. They can also be arranged at an intermediate level on the height of the analysis column, above the bottom, to measure the conductivity on the column height corresponding to the volume of the upper primary phase.
  • the analysis cell comprises two sets of independent electrodes, one extending from the bottom of the column and the other being superposed thereon.
  • the analysis column comprises electrodes in the form of bars which are arranged vertically; • the height of these electrodes is calibrated to correspond to the volume of the primary phases used.
  • the measurement electrodes are presented in pairs, the electrodes of each pair being placed facing each other near the walls of the analysis column.
  • the analysis equipment comprises computerized means which allow the automatic control of the measurements over time, the visualization of the raw data collected and the processing of this data for the acquisition of additional parameters.
  • the analysis equipment consists of a plurality of cells associated with a multiplexing system allowing the simultaneous measurement of a series of samples.
  • FIG. 1 illustrates, schematically, the equipment for implementing the invention
  • FIG. 2 is a curve which shows the change in conductivity over time of an emulsion tested with the device of Figure 1 provided with electrodes in the lower part of the column;
  • FIG. 3 shows the destabilization curve of the same emulsion, tested with the device of Figure 1 provided with electrodes arranged in the upper part of one emulsion.
  • the equipment for implementing the invention consists of an analysis cell 1 in the form of a regular vertical column, made of glass for example.
  • Column 1 is closed by a bottom 2; it can have a height of the order of 10 cm and a diameter close to h cm.
  • Column 1 comprises a pair of electrodes 3 connected to a conductivity meter A.
  • the two electrodes 3 are arranged vertically inside the cylindrical column 1; they start from the bottom 2 of the latter and they extend over a height h_.
  • the electrodes 3 can consist of stainless steel bars; more generally, their nature will be adapted to the conductivity measurement which it is desired to carry out.
  • the electrodes 3 are arranged opposite, near the walls of the cell 1. They can be spaced apart by a distance ⁇ d_ of the order of 3 cm; this spacing à_ is suitable for obtaining a quality measurement and, possibly, allowing the passage of a mixing device 5, of the mixer or sonicator type for example.
  • the analysis cell 1 with its electrodes 3 is adapted to characterize the stability of an emulsion.
  • This emulsion is produced by mixing two immiscible primary phases. This mixing can be carried out before introducing the sample which it is desired to test in column 1, by any suitable means; it can also be carried out within said column, by means of the mixer 5 for example.
  • the emulsion tested consists of a mixture of two primary phases, one ionized aqueous, conductive, the other lipidic, non-conductive; the products used to form this emulsion must be chosen and proportioned so that the continuous phase of the emulsion produced is conductive; on the other hand, the ionic strength must be little modified by the emulsion.
  • the quantities or volumes of the two primary phases used are adapted to the analysis equipment, that is to say to the dimensions of the cell 1 and to the height of the electrodes 3.
  • the method according to the invention in fact consists in measuring the conductivity and the evolution of conductivity within the emulsion, over the height of cell 1 which corresponds to the volume and the location of one of said primary phases.
  • the aqueous primary phase 6 is placed at the bottom of the column 1. Its volume is adapted to correspond to the height ji of the column.
  • the organic primary phase 7 extends above said aqueous phase 6, over the height j3 of the column.
  • the principle of the method according to the invention consists in measuring the variation in conductivity in the volume of one of the primary phases 6 or 7 produced by the incorporation of part of the other phase.
  • the positioning of the electrodes 3 on the device of FIG. 1 makes it possible to follow the quantity of organic phase 7 incorporated in the aqueous phase 6.
  • the emulsification is carried out at time J l_ by means of the mixer 5. We then notice the sudden drop in conductivity, linked to the incorporation of part of the organic phase 7 into the aqueous phase 6. At time tl, after emulsification , the emulsion is homogeneous and the conductivity has become Ci.
  • the decrease in conductivity measured is proportional to the amount of non-conductive phase dispersed in volume X. The greater this quantity, the greater the decrease in conductivity.
  • destabilization of the emulsion is then followed by measuring the change in conductivity (return to the value C_o).
  • destabilization curves (1) and (2) for example, whose slopes and conductivity values at a time _t characterize the stability of the emulsion.
  • the conductivity / time curves obtained characterize the stability of the emulsion.
  • the curve (1) of FIG. 2 corresponds to an emulsion within which the two primary phases separate quickly to arrive at an equilibrium conductivity Ce close to C_o; this emulsion is said to be unstable.
  • the curve (2) corresponds to a stable emulsion, within which the two phases remain partly emulsified (C_e much weaker than ⁇ _o).
  • computerized means 8 allow the visualization of the data collected and the processing of this data for the acquisition of additional parameters. We can thus draw curves, make a slope determination, calculate variations in volume, volume fraction, logarythmic transforms ... and more generally perform any desired mathematical manipulation.
  • the stability of the emulsion tested can also be characterized by measuring the change in conductivity over the height a_ of the cell, which corresponds to the volume and the location of the non-conductive organic phase 7.
  • the pair of electrodes 9, shown in dotted lines, is then placed at an intermediate level over the height of the column 1, above the level of the lower primary phase 6.
  • the electrodes 9 extend over the height and the level a_ of cell.
  • Curve (3) corresponds to a stable emulsion
  • curve (4) corresponds to an unstable emulsion for which the value of conductivity in the lipid phase decreases
  • This type of measurement takes into account all of the dispersed phases; it is independent of the opacity of the system.
  • Several cells of the same type can be grouped together and associated with a multiplexing system allowing the simultaneous measurement of a series of samples.
  • the measurement of the destabilization of the emulsions is then carried out on several tubes simultaneously, with a single conductometer whose analog values are digitized. The whole is controlled by suitable software coupled to electronic means.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
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Abstract

A method and equipment for determining the stability of an emulsion placed in an analyser cell and produced by mixing two non-miscible primary phases (6, 7), namely a conductive continuous phase and a non-conductive dispersed phase. The method comprises a step of measuring changes in conductivity within said emulsion in a portion of the cell which corresponds to the space occupied by one of said primary phases (6, 7) (either the conductive phase or the non-conductive phase) when they are at rest. The equipment for carrying out the method consists of an analyser cell (1) provided with conductivity measurement electrodes (3) connected to a conductivity meter. The electrodes (3) extend vertically through a portion of the cell column (1) and measure the conductivity of the sample being analysed therein, which portion corresponds to the space occupied by one of said primary phases (6, 7).

Description

PROCEDE ET MATERIEL DE CARACTERISATION DE LA STABILITE D'UNE EMULSION.METHOD AND MATERIAL FOR CHARACTERIZING THE STABILITY OF AN EMULSION.
La présente invention concerne un procédé et un matériel de caracterisation de la stabilité d'une emulsion .The present invention relates to a method and equipment for characterizing the stability of an emulsion.
Dans certains domaines techniques, il est essentiel de connaître précisément les propriétés émulsifiantes ou émulsionnantes des produits ou composés que l'on utilise.In certain technical fields, it is essential to know precisely the emulsifying or emulsifying properties of the products or compounds that are used.
En particulier, dans les domaines agro¬ alimentaire ou cosmétique, la connaissance de la capacité d'un produit à faciliter et/ou stabiliser une emulsion revêt une importance capitale pour obtenir les caractéristiques de stabilité, de texture, d'apparence, de durée de conservation et/ou de goût, désirées par les consommateurs.In particular, in the agro-food or cosmetic fields, knowing the capacity of a product to facilitate and / or stabilize an emulsion is of capital importance in order to obtain the characteristics of stability, texture, appearance, duration of conservation and / or taste, desired by consumers.
On connaît de nombreuses méthodes de détermination du pouvoir émulsifiant d'un produit, ou de caracterisation de la stabilité des émulsions. Dans tous les cas, la première étape consiste à réaliser une emulsion par brassage de deux phases primaires non miscibles, généralement l'une aqueuse et l'autre organique, en particulier lipidique ; l'une de ces phases est constante, l'autre constitue le produit à tester ou contient ce produit en suspension ou en solution. La technique consiste ensuite à suivre dans le temps la séparation de ces deux phases et à qualifier du mieux possible cette séparation.Numerous methods are known for determining the emulsifying power of a product, or for characterizing the stability of emulsions. In all cases, the first step consists in producing an emulsion by mixing two immiscible primary phases, generally one aqueous and the other organic, in particular lipidic; one of these phases is constant, the other constitutes the product to be tested or contains this product in suspension or in solution. The technique then consists in monitoring the separation of these two phases over time and in qualifying this separation as best as possible.
Les méthodes connues jusqu'à maintenant utilisent des principes et des technologies très différentes les unes des autres ; qu'elles mettent en oeuvre des techniques visuelles, des méthodes colorimétriques , par diffraction de la lumière ou autre ... , elles ne donnent pas entière satisfaction du fait, notamment, de la complexité des moyens mis en oeuvre, ou du manque de précision et de répétitivité des résultats.The methods known until now use very different principles and technologies from each other; that they use visual techniques, colorimetric methods, by light diffraction or other ..., they are not entirely satisfactory due in particular to the complexity of the means used, or the lack of precision and repeatability of results.
Un premier but de l'invention est de proposer un procédé et un matériel de caracterisation de la stabilité d'une emulsion qui utilisent une technologie simple et fiable. Un autre but de l'invention est de proposer un procédé et un matériel très faciles à mettre en oeuvre, qui rendent compte très précisément et de façon reproductible du pouvoir émulsifiant ou émulsionnant .A first object of the invention is to propose a method and a material for characterizing the stability of an emulsion which use a simple and reliable technology. Another object of the invention is to propose a process and a material very easy to implement, which very precisely and reproducibly account for the emulsifying or emulsifying power.
Un autre but de l'invention est de proposer une méthode standardisée de mesure des propriétés émulsifiantes qui, en liaison avec le matériel utilisé, permet d'étudier simultanément une série d' échantillons.Another object of the invention is to propose a standardized method for measuring the emulsifying properties which, in conjunction with the equipment used, makes it possible to simultaneously study a series of samples.
Le procédé selon l'invention permet la caracterisation de la stabilité d'une emulsion placée dans une cellule d'analyse. Cette emulsion peut être réalisée au sein même de la cellule ou en-dehors ; elle est réalisée par brassage de deux phases primaires non miscibles, la phase continue étant conductrice et la phase dispersée étant non conductrice. Ce procédé est caractérisé par le fait qu'il consiste à mesurer l'évolution de la conductivité au sein de ladite emulsion, ceci sur la hauteur de cellule qui correspond au volume et à l'emplacement de l'une desdites phases primaires .The method according to the invention allows the characterization of the stability of an emulsion placed in an analysis cell. This emulsion can be produced inside the cell or outside; it is carried out by mixing two immiscible primary phases, the continuous phase being conductive and the dispersed phase being non-conductive. This method is characterized by the fact that it consists in measuring the evolution of the conductivity within said emulsion, this over the cell height which corresponds to the volume and the location of one of said primary phases.
Après avoir réalisé 1 ' emulsion, on mesure l'évolution de conductivité sur une hauteur et un niveau bien déterminés de la cellule ; cette hauteur et ce niveau correspondent à l'emplacement soit de la phase conductrice, soit de la phase non conductrice lorsque lesdites phases sont séparées c'est-à-dire lorsqu'elles sont superposées dans la cellule.After having produced the emulsion, the conductivity evolution is measured over a well-determined height and level of the cell; this height and this level correspond to the location of either the conductive phase or the non-conductive phase when said phases are separated, that is to say when they are superimposed in the cell.
Cette caractéristique permet de raisonner en quantité de produit ; on détermine ainsi avec précision la concen ration de l'une des phases dans l'autre phase et on peut suivre cette variation de concentration dans le temps pour traduire la déstabilisation de 1 ' emulsion .This characteristic makes it possible to reason in quantity of product; the concentration of one of the phases in the other phase is thus precisely determined and this variation in concentration can be followed over time to reflect the destabilization of the emulsion.
La phase conductrice consiste en une phase aqueuse ionisée et la phase non conductrice est une phase lipidique ; la mesure de la conductivité sur toute la hauteur de l'une des phases dans la cellule d'analyse détermine la concentration d'eau dans l'huile ou d'huile dans l'eau, selon le cas.The conductive phase consists of an ionized aqueous phase and the non-conductive phase is a lipid phase; measurement of the conductivity over the entire height of one of the phases in the cell analysis determines the concentration of water in oil or oil in water, as appropriate.
Plus la quantité de phase lipidique incorporée dans la phase aqueuse (huile dans l'eau) de façon homogène, est élevée, plus la conductivité de ladite phase aqueuse diminue ; pour l'eau dans l'huile, la conductivité augmente. La variation de conductivité du volume de phase aqueuse ou lipidique qui est produite par l'incorporation d'huile dans l'eau ou d'eau dans l'huile traduit la déstabilisation de 1 ' emulsion .The more homogeneously the quantity of lipid phase incorporated into the aqueous phase (oil in water), the more the conductivity of said aqueous phase decreases; for water in oil, the conductivity increases. The variation in conductivity of the volume of aqueous or lipid phase which is produced by the incorporation of oil in water or of water in oil reflects the destabilization of the emulsion.
Le matériel pour la mise en oeuvre de ce procédé est constitué d'une cellule d'analyse en forme de colonne, obturée par un fond, à sa partie inférieure. Cette colonne comporte des électrodes de mesure de conductivité, reliées à un conductimètre ; ces électrodes s'étendent sur une partie de la hauteur de ladite colonne, pour mesurer la conductivité de l'échantillon analysé sur toute cette hauteur.The equipment for the implementation of this process consists of a column-shaped analysis cell, closed by a bottom, at its lower part. This column includes conductivity measurement electrodes, connected to a conductivity meter; these electrodes extend over part of the height of said column, to measure the conductivity of the sample analyzed over this entire height.
Les électrodes de mesure de conductivité peuvent s'étendre à partir du fond de la colonne, pour mesurer la conductivité sur la hauteur de colonne qui correspond à la hauteur et au volume de la phase primaire inférieure. Elles peuvent également être disposées à un niveau intermédiaire sur la hauteur de la colonne d'analyse, au-dessus du fond, pour mesurer la conductivité sur la hauteur de colonne correspondant au volume de la phase primaire supérieure .The conductivity measuring electrodes can extend from the bottom of the column, to measure the conductivity over the column height which corresponds to the height and volume of the lower primary phase. They can also be arranged at an intermediate level on the height of the analysis column, above the bottom, to measure the conductivity on the column height corresponding to the volume of the upper primary phase.
Dans un mode de réalisation dérivé, la cellule d'analyse comporte deux jeux d'électrodes indépendants, l'un s'étendant à partir du fond de la colonne et l'autre lui étant superposé.In a derivative embodiment, the analysis cell comprises two sets of independent electrodes, one extending from the bottom of the column and the other being superposed thereon.
Selon une autre disposition de l'invention, la colonne d'analyse comporte des électrodes en forme de barrettes qui sont disposées verticalement ; • la hauteur de ces électrodes est calibrée pour correspondre au volume des phases primaires utilisées. De préférence, les électrodes de mesure se présentent par couple(s), les électrodes de chaque couple étant disposées en vis-à-vis à proximité des parois de la colonne d'analyse.According to another arrangement of the invention, the analysis column comprises electrodes in the form of bars which are arranged vertically; • the height of these electrodes is calibrated to correspond to the volume of the primary phases used. Preferably, the measurement electrodes are presented in pairs, the electrodes of each pair being placed facing each other near the walls of the analysis column.
Selon une autre caractéristique, le matériel d'analyse comporte des moyens informatisés qui permettent le pilotage automatique des mesures dans le temps, la visualisation des données brutes recueillies et le traitement de ces données pour l'acquisition de paramètres supplémentaires.According to another characteristic, the analysis equipment comprises computerized means which allow the automatic control of the measurements over time, the visualization of the raw data collected and the processing of this data for the acquisition of additional parameters.
Selon une autre caractéristique, le matériel d'analyse est constitué d'une pluralité de cellules associées à un système de multiplexage permettant la mesure simultanée d'une série d'échantillons.According to another characteristic, the analysis equipment consists of a plurality of cells associated with a multiplexing system allowing the simultaneous measurement of a series of samples.
Mais l'invention sera encore illustrée, sans être aucunement limitée, par la description suivante d'un mode de réalisation particulier, donné à titre d'exemple et représenté sur les dessins annexés dans lesquels : la figure 1 illustre, de façon schématique, le matériel pour la mise en oeuvre de l'invention ;However, the invention will be further illustrated, without being in any way limited, by the following description of a particular embodiment, given by way of example and shown in the appended drawings in which: FIG. 1 illustrates, schematically, the equipment for implementing the invention;
- la figure 2 est une courbe qui montre l'évolution de conductivité dans le temps d'une emulsion testée avec le dispositif de la figure 1 muni d'électrodes dans la partie inférieure de la colonne ;- Figure 2 is a curve which shows the change in conductivity over time of an emulsion tested with the device of Figure 1 provided with electrodes in the lower part of the column;
- la figure 3 montre la courbe de déstabilisation de la même emulsion, testée avec le dispositif de la figure 1 muni d'électrodes disposées dans la partie supérieure de 1 ' emulsion.- Figure 3 shows the destabilization curve of the same emulsion, tested with the device of Figure 1 provided with electrodes arranged in the upper part of one emulsion.
Tel qu'on l'a représenté sur la figure 1, le matériel pour la mise en oeuvre de l'invention est constitué d'une cellule d'analyse 1 en forme de colonne régulière verticale, en verre par exemple. La colonne 1 est obturée par un fond 2 ; elle peut avoir une hauteur de l'ordre de 10 cm et un diamètre voisin de h cm.As shown in FIG. 1, the equipment for implementing the invention consists of an analysis cell 1 in the form of a regular vertical column, made of glass for example. Column 1 is closed by a bottom 2; it can have a height of the order of 10 cm and a diameter close to h cm.
La colonne 1 comporte un couple d'électrodes 3 reliées à un conductimètre A. Les deux électrodes 3 sont disposées verticalement à l'intérieur de la colonne cylindrique 1 ; elles partent du fond 2 de cette dernière et elles s'étendent sur une hauteur h_. Les électrodes 3 peuvent consister en des barrettes inox ; plus généralement, leur nature sera adaptée à la mesure de conductivité que l'on désire réaliser.Column 1 comprises a pair of electrodes 3 connected to a conductivity meter A. The two electrodes 3 are arranged vertically inside the cylindrical column 1; they start from the bottom 2 of the latter and they extend over a height h_. The electrodes 3 can consist of stainless steel bars; more generally, their nature will be adapted to the conductivity measurement which it is desired to carry out.
Les électrodes 3 sont disposées en vis-à- vis, à proximité des parois de la cellule 1. Elles peuvent être espacées d'une distance ιd_ de l'ordre de 3 cm ; cet espacement à_ est adapté pour obtenir une mesure de qualité et, éventuellement, permettre le passage d'un dispositif de brassage 5, du genre mixeur ou sonificateur par exemple.The electrodes 3 are arranged opposite, near the walls of the cell 1. They can be spaced apart by a distance ιd_ of the order of 3 cm; this spacing à_ is suitable for obtaining a quality measurement and, possibly, allowing the passage of a mixing device 5, of the mixer or sonicator type for example.
La cellule d'analyse 1 avec ses électrodes 3 est adaptée pour caractériser la stabilité d'une emulsion .The analysis cell 1 with its electrodes 3 is adapted to characterize the stability of an emulsion.
Cette emulsion est réalisée par brassage de deux phases primaires non miscibles. Ce brassage peut être réalisé avant d'introduire l'échantillon que l'on désire tester dans la colonne 1 , par tout moyen approprié ; il peut également être réalisé au sein même de ladite colonne, au moyen du mixeur 5 par exemple.This emulsion is produced by mixing two immiscible primary phases. This mixing can be carried out before introducing the sample which it is desired to test in column 1, by any suitable means; it can also be carried out within said column, by means of the mixer 5 for example.
L'émulsion testée consiste en un mélange de deux phases primaires, l'une aqueuse ionisée, conductrice, l'autre lipidique, non conductrice ; les produits utilisés pour former cette emulsion doivent être choisis et proportionnés pour que la phase continue de l'émulsion réalisée soit conductrice ; d'autre part, la force ionique doit être peu modifiée par l'émulsion.The emulsion tested consists of a mixture of two primary phases, one ionized aqueous, conductive, the other lipidic, non-conductive; the products used to form this emulsion must be chosen and proportioned so that the continuous phase of the emulsion produced is conductive; on the other hand, the ionic strength must be little modified by the emulsion.
Les quantités ou volumes des deux phases primaires utilisées sont adaptés au matériel d'analyse, c'est-àdire aux dimensions de la cellule 1 et à la hauteur des électrodes 3.The quantities or volumes of the two primary phases used are adapted to the analysis equipment, that is to say to the dimensions of the cell 1 and to the height of the electrodes 3.
Le procédé selon l'invention consiste en effet à mesurer la conductivité et l'évolution de conductivité au sein de l'émulsion, sur la hauteur de la cellule 1 qui correspond au volume et à l'emplacement de l'une desdites phases primaires. Tel qu'on peut le voir sur la figure 1, avant emulsion, la phase primaire aqueuse 6 est placée dans le fond de la colonne 1. Son volume est adapté pour correspondre à la hauteur ji de colonne. Par le jeu des densités, la phase primaire organique 7 s'étend au-dessus de ladite phase aqueuse 6, sur la hauteur j3 de colonne .The method according to the invention in fact consists in measuring the conductivity and the evolution of conductivity within the emulsion, over the height of cell 1 which corresponds to the volume and the location of one of said primary phases. As can be seen in FIG. 1, before emulsion, the aqueous primary phase 6 is placed at the bottom of the column 1. Its volume is adapted to correspond to the height ji of the column. By the play of densities, the organic primary phase 7 extends above said aqueous phase 6, over the height j3 of the column.
Le principe du procédé selon l'invention consiste à mesurer la variation de conductivité dans le volume de l'une des phases primaires 6 ou 7 produite par l'incorporation d'une partie de l'autre phase.The principle of the method according to the invention consists in measuring the variation in conductivity in the volume of one of the primary phases 6 or 7 produced by the incorporation of part of the other phase.
Ainsi, après mélange homogène des deux phases 6 et 7 (brassage) on suit la variation de la concentration en phase aqueuse (ou en phase organique) par la variation de la conductivité qui traduit la déstabilisation de l'émulsion.Thus, after homogeneous mixing of the two phases 6 and 7 (stirring), the variation in the concentration in the aqueous phase (or in the organic phase) is followed by the variation in the conductivity which reflects the destabilization of the emulsion.
Le positionnement des électrodes 3 sur le dispositif de la figure 1 permet de suivre la quantité de phase organique 7 incorporée dans la phase aqueuse 6.The positioning of the electrodes 3 on the device of FIG. 1 makes it possible to follow the quantity of organic phase 7 incorporated in the aqueous phase 6.
Après brassage, on obtient des courbes de déstabilisation du type de celles représentées sur la figure 2.After stirring, destabilization curves of the type of those shown in FIG. 2 are obtained.
Sur ces courbes, on remarque la valeur de conductivité élevée C_o qui correspond à la conductivité de la phase aqueuse 6, avant emulsion.On these curves, we note the high conductivity value C_o which corresponds to the conductivity of the aqueous phase 6, before emulsion.
L ' émulsification est réalisée au temps J l_ au moyen du mixeur 5. On remarque alors la chute brutale de conductivité, liée à l'incorporation d'une partie de la phase organique 7 dans la phase aqueuse 6. Au temps tl , après émulsification , l'émulsion est homogène et la conductivité est devenue Ci .The emulsification is carried out at time J l_ by means of the mixer 5. We then notice the sudden drop in conductivity, linked to the incorporation of part of the organic phase 7 into the aqueous phase 6. At time tl, after emulsification , the emulsion is homogeneous and the conductivity has become Ci.
Le volume total de l'émulsion est _V = _X + _Y où:The total volume of the emulsion is _V = _X + _Y where:
- _X est le volume de phase aqueuse 6 conductrice et,- _X is the volume of conductive aqueous phase 6 and,
- _Y est le volume de phase organique 7 non conductrice.- _Y is the volume of non-conductive organic phase 7.
La dilution du volume _X de phase aqueuse est: X7_V et Ci = Ço x (JΛV + Y_) .The dilution of the volume _X of aqueous phase is: X7_V and Ci = Ço x (JΛV + Y_).
La diminution de la conductivité mesurée est propor ionnelle à la quantité de phase non conductrice dispersée dans le volume X . Plus cette .quantité sera grande, plus la diminution de conductivité sera importante .The decrease in conductivity measured is proportional to the amount of non-conductive phase dispersed in volume X. The greater this quantity, the greater the decrease in conductivity.
On suit ensuite la déstabilisation de l'émulsion par la mesure de l'évolution de la conductivité (retour vers la valeur C_o) . On obtient alors des courbes de déstabilisation (1) et (2), par exemple, dont les pentes et les valeurs de conductivité à un temps _t caractérisent la stabilité de l'émulsion.The destabilization of the emulsion is then followed by measuring the change in conductivity (return to the value C_o). We then obtain destabilization curves (1) and (2), for example, whose slopes and conductivity values at a time _t characterize the stability of the emulsion.
Les courbes conductivité/temps obtenues caractérisent la stabilité de l'émulsion. La courbe (1) de la figure 2 correspond à une emulsion au sein de laquelle les deux phases primaires se séparent rapidement pour arriver à une conductivité d'équilibre Ce proche de C_o ; cette emulsion est dite instable. La courbe (2) correspond à une emulsion stable, au sein de laquelle les deux phases restent en partie émulsionnées (C_e beaucoup plus faible que Ç_o) .The conductivity / time curves obtained characterize the stability of the emulsion. The curve (1) of FIG. 2 corresponds to an emulsion within which the two primary phases separate quickly to arrive at an equilibrium conductivity Ce close to C_o; this emulsion is said to be unstable. The curve (2) corresponds to a stable emulsion, within which the two phases remain partly emulsified (C_e much weaker than Ç_o).
A partir des données brutes de conductivité délivrées par le conductimètre A, des moyens informatisés 8 permettent la visualisation des données recueillies et le traitement de ces données pour l'acquisition de paramètres supplémentaires. On peut ainsi tracer des courbes, faire une détermination de pente, calculer les variations de volume, de fraction volumique, les transformées logarythmiques ... et plus généralement effectuer toute manipulation mathématique désirée .From the raw conductivity data delivered by the conductivity meter A, computerized means 8 allow the visualization of the data collected and the processing of this data for the acquisition of additional parameters. We can thus draw curves, make a slope determination, calculate variations in volume, volume fraction, logarythmic transforms ... and more generally perform any desired mathematical manipulation.
En utilisant les courbes de déstabilisation obtenues, on peut définir le pourcentage de l'une des phases dans les volumes X ou Y_.Using the destabilization curves obtained, we can define the percentage of one of the phases in volumes X or Y_.
D'autre part, ces moyens informatisés 8 permettent le pilotage automatique des mesures dans le temps .On the other hand, these computerized means 8 allow automatic control of the measurements over time.
D'une façon analogue, on peut également caractériser la stabilité de l'émulsion testée en mesurant l'évolution de conductivité sur la hauteur a_ de cellule qui correspond au volume et à l'emplacement de la phase organique 7, non conductrice. Le couple d'électrodes 9, représenté en pointillés, est alors disposé à un niveau intermédiaire sur la hauteur de la colonne 1, au-dessus du niveau de la phase primaire inférieure 6. Les électrodes 9 s'étendent sur la hauteur et le niveau a_ de cellule.Similarly, the stability of the emulsion tested can also be characterized by measuring the change in conductivity over the height a_ of the cell, which corresponds to the volume and the location of the non-conductive organic phase 7. The pair of electrodes 9, shown in dotted lines, is then placed at an intermediate level over the height of the column 1, above the level of the lower primary phase 6. The electrodes 9 extend over the height and the level a_ of cell.
Des exemples de courbes obtenus par un dispositif de ce genre sont représentés sur la figure 3. Avant émulsification, on remarque que la conductivité Co est nulle ; elle correspond à la conductivité deExamples of curves obtained by a device of this kind are shown in FIG. 3. Before emulsification, it is noted that the conductivity Co is zero; it corresponds to the conductivity of
10 la phase organique. Juste après 1 ' émulsification , au temps _tl_, la conductivité augmente jusqu'à une valeur Ci qui correspond à l'homogénéité de l'émulsion. Cette augmentation de conductivité est liée à l'incorporation . _- de phase aqueuse conductrice dans la phase lipidique.10 the organic phase. Just after the emulsification, at time _tl_, the conductivity increases to a value Ci which corresponds to the homogeneity of the emulsion. This increase in conductivity is linked to incorporation. _- of conductive aqueous phase in the lipid phase.
La déstabilisation de l'émulsion se traduit ensuite par une diminution de la conductivité. La courbe (3) correspond à une emulsion stable ; la courbe (4) correspond à une emulsion instable pour laquelle la valeur de conductivité dans la phase lipidique décroîtThe destabilization of the emulsion then results in a decrease in the conductivity. Curve (3) corresponds to a stable emulsion; curve (4) corresponds to an unstable emulsion for which the value of conductivity in the lipid phase decreases
20 rapidement pour arriver à des valeurs proches de Co.20 quickly to arrive at values close to Co.
Sur un même dispositif de mesure, il est possible d'envisager d'utiliser deux couples d'électrodes 3 et 9, reliées à des conductimètres indépendants pour suivre l'évolution de conductivité dans chaque phaseOn the same measuring device, it is possible to envisage using two pairs of electrodes 3 and 9, connected to independent conductimeters to follow the evolution of conductivity in each phase
25 primaire .25 primary.
Ce procédé et le dispositif correspondant permettent de caractériser la stabilité d'une emulsion, de façon très fine et répétitive. Ils peuvent notammentThis process and the corresponding device make it possible to characterize the stability of an emulsion, in a very fine and repetitive manner. They can in particular
30 être utilisés pour étudier le pouvoir émulsionnant de protéines alimentaires, c'est-à-dire la capacité de produits en suspension dans une phase aqueuse à stabiliser une emulsion. Il est également possible de vérifier l'effet des huiles en utilisant un -* <- émulsionnant constant en phase aqueuse.30 be used to study the emulsifying power of food proteins, that is to say the capacity of products in suspension in an aqueous phase to stabilize an emulsion. It is also possible to check the effect of oils using - * <- constant emulsifier in aqueous phase.
Ce type de mesure prend en compte la totalité des phases dispersées ; elle est indépendante de l'opacité du système. Plusieurs cellules du même type, peuvent être regroupées et associées à un système de multiplexage permettant la mesure simultanée d'une série d 'échantillons.This type of measurement takes into account all of the dispersed phases; it is independent of the opacity of the system. Several cells of the same type can be grouped together and associated with a multiplexing system allowing the simultaneous measurement of a series of samples.
La mesure de la déstabilisation des emulsions est alors conduite sur plusieurs tubes simultanément, avec un seul conductimetre dont les valeurs analogiques sont numérisées. L'ensemble est piloté par un logiciel adapté couplé à des moyens électroniques. The measurement of the destabilization of the emulsions is then carried out on several tubes simultaneously, with a single conductometer whose analog values are digitized. The whole is controlled by suitable software coupled to electronic means.

Claims

- REVENDICATIONS - 1.- Procédé de caracterisation de la stabilité d'une emulsion placée dans une cellule d'analyse et obtenue par brassage de deux phases primaires non miscibles, la phase continue de ladite emulsion étant conductrice et la phase dispersée non conductrice, caractérisé en ce qu'il consiste à mesurer l'évolution de la conductivité au sein de ladite emulsion, sur la hauteur de cellule qui correspond au volume et à- CLAIMS - 1.- Process for characterizing the stability of an emulsion placed in an analysis cell and obtained by mixing two immiscible primary phases, the continuous phase of said emulsion being conductive and the dispersed phase non-conductive, characterized in that it consists of measuring the evolution of the conductivity within said emulsion, over the cell height which corresponds to the volume and to
10 l'emplacement de l'une desdites phases primaires.10 the location of one of said primary phases.
2.- Procédé selon la revendication 1, caractérisé en ce qu'il consiste à mesurer l'évolution de la conductivité, après emulsion, sur la hauteur de la cellule qui correspond à la phase conductrice, avant i emulsion.2.- Method according to claim 1, characterized in that it consists of measuring the evolution of the conductivity, after emulsion, over the height of the cell which corresponds to the conductive phase, before emulsion.
3.- Procédé selon la revendication 1, caractérisé en ce qu'il consiste à mesurer l'évolution de la conductivité, après emulsion, sur la hauteur de la cellule qui correspond à la phase non conductrice,3.- Method according to claim 1, characterized in that it consists of measuring the evolution of the conductivity, after emulsion, over the height of the cell which corresponds to the non-conductive phase,
20 avant emulsion.20 before emulsion.
4.- Matériel pour la mise en oeuvre du procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce qu'il est constitué d'une cellule d'analyse (1) en forme de colonne obturée par un fond4.- Equipment for implementing the method according to any one of claims 1 to 3, characterized in that it consists of an analysis cell (1) in the shape of a column closed by a bottom
25 (2) à sa partie inférieure, laquelle colonne (1) comporte des électrodes (3, 9) de mesure de conductivité reliées à un conductimetre (4), lesdites électrodes (3, 9) s'étendant sur une partie de la hauteur de ladite colonne (1), pour mesurer la Q conductivité de l'échantillon analysé, sur toute cette hauteur .25 (2) at its lower part, which column (1) comprises electrodes (3, 9) for measuring conductivity connected to a conductivity meter (4), said electrodes (3, 9) extending over part of the height of said column (1), to measure the Q conductivity of the sample analyzed, over this entire height.
5.- Matériel selon la revendication 4, caractérisé en ce qu'il comporte des électrodes (3) de mesure de conductivité qui s'étendent à partir du 5 fond (2) de la colonne (1) pour mesurer la conductivité sur la hauteur de colonne qui correspond à la hauteur et au volume de la phase primaire (6) inférieure.5.- Equipment according to claim 4, characterized in that it comprises electrodes (3) for measuring conductivity which extend from the bottom (2) of the column (1) to measure the conductivity over the height column which corresponds to the height and volume of the lower primary phase (6).
6.- Matériel selon l'une quelconque des revendications 4 ou 5, caractérisé en ce qu'il comporte des électrodes (9) de mesure de conductivité qui sont disposés à un niveau intermédiaire sur la hauteur de la colonne d'analyse (1), au-dessus de son fond (2), pour mesurer la conductivité sur la hauteur de colonne correspondant au volume de la - phase primaire (7) supérieure .6.- Material according to any of the claims 4 or 5, characterized in that it comprises electrodes (9) for measuring conductivity which are arranged at an intermediate level on the height of the analysis column (1), above its bottom (2) , to measure the conductivity on the column height corresponding to the volume of the upper primary phase (7).
1 . - Matériel selon l'une quelconque des revendications 4 à 6, caractérisé en ce qu'il comporte des électrodes (3, 9) en forme de barrettes, disposées verticalement, dont la hauteur est adaptée au volume des phases primaires (6, 1. - Equipment according to any one of claims 4 to 6, characterized in that it comprises electrodes (3, 9) in the form of bars, arranged vertically, the height of which is adapted to the volume of the primary phases (6,
7) que l'on place dans la cellule d'analyse (1).7) which is placed in the analysis cell (1).
8.- Matériel selon la revendication 7, caractérisé en ce que les électrodes de mesure se présentent par couple(s), les électrodes de chaque couple étant disposées en vis-à-vis, à proximité des parois de la colonne d'analyse.8.- Equipment according to claim 7, characterized in that the measuring electrodes are presented in pairs, the electrodes of each pair being arranged opposite each other, close to the walls of the analysis column.
9.- Matériel selon l'une quelconque des revendications 4 à 8, caractérisé en ce qu'il comporte des moyens informatisés (8) qui permettent le pilotage automatique des mesures dans le temps, la visualisation des données brutes recueillies et le traitement de ces données pour l'acquisition de paramètres supplémentaires.9.- Equipment according to any one of claims 4 to 8, characterized in that it comprises computerized means (8) which allow the automatic control of measurements over time, the visualization of the raw data collected and the processing of these data for the acquisition of additional parameters.
10.- Matériel selon l'une quelconque des revendications 4 à 9, caractérisé en ce qu'il est constitué d'une pluralité de cellules d'analyse (1) associées à un système multiplexage permettant la mesure simultanée d'une série d'échantillons. 10.- Equipment according to any one of claims 4 to 9, characterized in that it consists of a plurality of analysis cells (1) associated with a multiplexing system allowing the simultaneous measurement of a series of samples.
PCT/FR1994/001237 1993-10-28 1994-10-24 Method and equipment for determining the stability of an emulsion WO1995012122A1 (en)

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FR93/13027 1993-10-28

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FR2772129A1 (en) * 1997-12-04 1999-06-11 Didier Roux APPARATUS AND METHODS FOR MEASUREMENT ON A FLOWING FLOW WITH SHEAR
CN101487813B (en) * 2008-12-15 2011-12-28 中国石油化工股份有限公司 Test method for self-emulsifying ability of emulsified mixture

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GB9906214D0 (en) * 1999-03-18 1999-05-12 Hamelin Holdings Limited Surfactants
US20080319582A1 (en) * 2005-09-28 2008-12-25 Gerd Dahms Device for In-Line Process Control During the Production of Emulsions or Dispersions

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FR2476350A1 (en) * 1979-10-29 1981-08-21 United States Surgical Corp SYSTEM FOR MEASURING THE CONDUCTIVITY OF A LIQUID
DE3427050A1 (en) * 1984-07-23 1986-01-30 HDW-Elektronik GmbH, 2300 Kiel A compact C-T-D probe
FR2636736A1 (en) * 1988-09-20 1990-03-23 Pechiney Recherche DEVICE AND METHOD FOR CONTINUOUSLY MEASURING THE ELECTRICAL CONDUCTIVITY OF LIQUID MEDIA IN A DYNAMIC CELL

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DE2632048A1 (en) * 1976-07-16 1978-01-26 Bold Karl Wilhelm Control of homogenisation processes - using electrical conductivity as control parameter
FR2476350A1 (en) * 1979-10-29 1981-08-21 United States Surgical Corp SYSTEM FOR MEASURING THE CONDUCTIVITY OF A LIQUID
DE3427050A1 (en) * 1984-07-23 1986-01-30 HDW-Elektronik GmbH, 2300 Kiel A compact C-T-D probe
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2772129A1 (en) * 1997-12-04 1999-06-11 Didier Roux APPARATUS AND METHODS FOR MEASUREMENT ON A FLOWING FLOW WITH SHEAR
WO1999030129A1 (en) * 1997-12-04 1999-06-17 Philippe Sierro Method for characterising complex fluids and appliances resulting from said method
US6535796B1 (en) 1997-12-04 2003-03-18 Rheocontrol Method for characterizing complex fluids and appliances resulting from said method
CN101487813B (en) * 2008-12-15 2011-12-28 中国石油化工股份有限公司 Test method for self-emulsifying ability of emulsified mixture

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FR2711800A1 (en) 1995-05-05
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