Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/96—Cosmetics or similar toiletry preparations characterised by the composition containing materials, or derivatives thereof of undetermined constitution
  • A61K8/97—Cosmetics or similar toiletry preparations characterised by the composition containing materials, or derivatives thereof of undetermined constitution from algae, fungi, lichens or plants; from derivatives thereof
  • A61K8/9706—Algae
  • A61K8/9711—Phaeophycota or Phaeophyta [brown algae], e.g. Fucus
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q19/00—Preparations for care of the skin
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
  • A61K2800/10—General cosmetic use
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
  • A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
  • A61K2800/48—Thickener, Thickening system

Definitions

• the present invention relates to the field of rheology agents for dispersions, in particular aqueous dispersions in the food or cosmetics fields.
• Alginates are derived from seaweed and are used as thickeners, gelling agents, emulsifiers and stabilizers in the most varied industrial products, from food jellies, beauty products, to paints and printing inks. In the food industry, they are used in particular as texturizing agents to reconstruct foods by forming hard and thermostable gels, or to provide a creamy texture to foods.
• the suspensory or anti-settling control of liquid formulations generally requires the addition of viscosity agents (not very effective) and/or gelling agents.
• the alginates and the viscosifying and gelling agents conventionally used have shear-thinning properties but they have a high viscosity or elastic modulus and a high threshold stress.
• the control of the suspension or the settling exerted by these agents inevitably leads to a texturing of the formula which generally remains too important even under shear and which thus sometimes appears not compatible with the specific specifications of certain formulations for which it is advisable to have low viscosities under low stresses (organoleptic properties for example).
• Fluid gels are solutions that exhibit low modulus elastic gel behavior, flowing with high shear fluidity under the action of very low stress. These fluid gel properties can advantageously be used to stabilize the dispersions.
• WO 2015/004403 describes the production of exopolysaccharides obtained from microorganisms such as microalgae.
• the micro-algae belonging to the genus Glossomastix can produce one or more polysaccharide(s) which exhibit(s) original rheological properties of the fluid gel (or fragile gel) type.
• the present invention relates to the use of an exopolysaccharide or mixture of exopolysaccharides derived from the microalgae belonging to the genus Glossomastix. as a texturizing agent.
• micro-algae refers to microscopic algae, sometimes called microphytes.
• the microalgae belong to the genus Glossomastix, and more particularly to the species Glossomastix sp. RCC 3688 and Glossomastix sp. RCC 3707, deposited at the Collection de Cultures de Roscoff (RCC).
• exopolysaccharides of the invention are derived from the following strains:
• Glossomastix sp. RCC3688 strain deposited at the Culture Collection of Algae and Protozoa (CCAP) international depositary authority on December 9, 2020 under number CCAP 2912/2.
• texturizing agent is understood to mean an agent which, when it is added to a dispersion, makes it possible to stabilize the dispersions. According to one embodiment, this property is achieved when said texturizing agent has fluid gel properties, when it is in aqueous solution.
• fluid gel is meant a solution which exhibits elastic gel behavior with a low modulus (typically less than 10 Pa) but which flows with high shear fluidity under the action of a very low stress (typically less than 1 Pa) .
• the fluid gel properties of the exopolysaccharides according to the invention make it possible to control the settling or the creaming of suspensions or emulsions without altering the properties of low viscosities under low stresses.
• exopolysaccharides make it possible to stabilize dispersions by the formation of a three-dimensional network of physical origin and therefore reversible of polymer chain in the absence of any constraint. Under the action of a weak stress, the system flows in a non-Newtonian and shear-thinning way.
• the exopolysaccharides according to the invention make it possible to obtain these fluid gel properties, whereas several additives are generally necessary.
• solutions of these polysaccharides are very strongly shear-thinning even at low concentration, and have relatively low threshold stresses, typically less than 1 Pa up to 10 gL 1 in exopolysaccharides.
• the dispersions according to the invention typically have a concentration of between 0.1 and 50 g/L in exopolysaccharides, and/or a threshold stress of between 10 ⁇ 2 and 10 Pa.
• the solution exhibits a gel-like behavior (G'>G”) but with very low modulus values (typically depending on the polysaccharide concentration). Above this threshold stress, the behavior of the solution is of the viscous type (G' ⁇ G").
• This fluid gel type behavior can be used to stabilize dispersions (solid/liquid/air in an aqueous solution) without significantly affecting the rheological behavior of the dispersion.
• these 'fluid gel' type solutions behave - at rest as a very low modulus gel which can block or considerably slow down the settling or creaming of suspensions or emulsions for example
• the system is therefore a shear-thinning liquid with very low gel properties under very low stress.
• fluid gel-like behavior is obtained for exopolysaccharides from the aforementioned Glossomastix while other microalgae produce polysaccharides that do not exhibit fluid gel-like behavior but rather more classic solution behavior comparable to that of polysaccharides extracted from macro-algae such as alginates.
• the fluid gel properties are therefore specific to the producing microalgae.
• exopolysaccharides designates the polysaccharides secreted by the micro-algae in the extracellular medium, the polysaccharides being defined as polymers of oses of the family of carbohydrates consisting of several oses linked together by osidic bonds.
• the exopolysaccharides which can be used according to the invention are native exopolysaccharides.
• the exopolysaccharides generally have a molecular weight greater than 100 kDa, typically between 1,000,000 Da and several million Da, in particular 10 9 Da.
• Osidic composition characterizing a galacturono-rhamno-fucan (11% galacturonic acid, 20% rhamnose, 56% fucose), also having in smaller proportions: glucuronic acid (11%) and galactose (2%).
• Osidic composition characterizing a galacturono-rhamno-fucan (19% galacturonic acid, 27% rhamnose, 44% fucose), also having in smaller proportions: glucuronic acid (6%) and galactose (4%).
• said exopolysaccharide therefore has a galacturono-rhamno-fucan type structure
• the exopolysaccharide has an osidic composition characterizing a galacturono-rhamno-fucan with contents for the various sugars of between 40 and 60% fucose, between 20 and 30% rhamnose and between 10 and 20% galacturonic acid .
• CCAP International depositary authority Culture Collection of Algae and Protozoa
• a strain is defined here as a low-level taxonomic rank representing a subtype of microalgae.
• the exopolysaccharides according to the invention can be obtained in the following way:
• the microalgae culture medium is an enriched F/2 culture medium.
• the composition of the enriched F/2 medium is based on that of the F/2 medium described by Guillard and Ryther (Studies of marine planktonic diatoms. I. Cyclotella nana Flustedt and Detonula confervacea Cleve. Can. J. Microbiol. 8: 229-239 , 1962), with increased levels of nitrogen and phosphorus sources.
• the culture conditions include culture in Erlen or airlift, at ambient temperature (for example approximately at 20° C.), under irradiance between 40 and 300 pmolphotons/m 2 /s with a day/night cycle or continuous illumination, under agitation between 0 and 120 rpm, more particularly in airlift without agitation, in an Erlenmeyer flask.
• exopolysaccharides are excreted by microalgae, they are present in culture media. Their separation can be carried out by collecting culture supernatants in which they are soluble after centrifugation.
• This collection therefore generally does not require any intracellular extraction step. This has the advantage of reducing the cost of obtaining the raw material.
• the supernatants are then treated by tangential ultrafiltration by series of dilution concentrations (membrane with a cut-off threshold of 50 kDa).
• the dilution concentration cycles are carried out until a stable conductivity is obtained (close to 2 pS.cnr 1 in the permeate) in order to eliminate the salts and molecules of low molar mass from the culture medium, then freezing and drying , for example by freeze-drying.
• the process for obtaining exopolysaccharides comprises the step of obtaining the exopolysaccharide from the micro-algae by:
• the present invention also relates to a liquid formulation comprising an exopolysaccharide as defined above.
• said formulation may be a concentrated aqueous solution (10 to 50 g/L) of said exopolysaccharide, of the fluid gel type.
• Said formulation can be obtained by dissolving the exopolysaccharide in water. It can advantageously be used as a texturizing additive to stabilize dispersions.
• said formulation may be a dispersion of particles or nanoparticles, comprising said exopolysaccharide at a lower concentration (in particular from 0.01 to 5 g/L, particularly from 0.1 to 5 g/L).
• said dispersion is a stable aqueous dispersion, chosen in particular from aqueous emulsions or aqueous suspensions.
• composition refers to any heterogeneous mixture of two liquids or of a solid in a liquid.
• emulsions Two types of dispersion can thus be distinguished: emulsions and dispersions.
• emulsion is meant a heterogeneous mixture of two immiscible liquid substances, one being dispersed in the form of small droplets in the other.
• suspension is meant a mixture in which a finely divided product is combined with a liquid, and in which it is insoluble.
• the present invention therefore also relates to a method for stabilizing an aqueous dispersion comprising the aforementioned.
• Stabilization is understood here to mean the inhibition or delay of settling or creaming in particular.
• Said dispersions may in particular be dispersions in the cosmetics and agri-food fields:
• Figure 1 represents the viscosity of alginate (filled and empty triangles) and of EPS-Pav (filled and empty circles) at 20 gL -1 between 0.1 and 1000 s -1 .
• Figure 2 represents the elastic and viscous moduli of Alginate (solid G' and G” empty triangles) and EPS-Pav (solid G' and G” empty circles) at 20 gL -1 between 0.1 and 10 Hz .
• Figure 3 represents the viscosity of EPS-3707 (forward curves: filled symbols; return curves: empty symbols). 20 gL -1 , 10 gL -1 ⁇ , 5 gL -1 ⁇ , 1 gL 1 ⁇ and 0.5 gL 1 x.
• Figure 4 represents the elastic and viscous moduli of EPS-3707 (solid symbols G' and empty symbols G”) between 0.001 and 10Hz. 20 gL -1 , 10 gL -1 ⁇ , 5 gL -1
• Figure 5 represents the viscosity of EPS-3688 (forward curves: filled symbols; return curves: empty symbols) between 0.1 and 1000 s -1 , 20 gL 1 ⁇ , 10 gL 1 ⁇ , 5 gL 1 ⁇ , 1 gL 1 ⁇ and 0.5 gL 1 x.
• Figure 6 represents the elastic and viscous moduli of EPS-3688 (solid symbols G' and empty symbols G”) between 0.01 and 10 Hz; 20 gL -1 , 10 gL -1 ⁇ , 5 gL -1
• Figure 7 shows the complex viscosity of EPS-3707 solutions in water at 20 gL 1 , 10 gL -1 ⁇ , 5 gL -1 ⁇ and 1 gL -1 ⁇ compared to EPS-Pav20 gL -1 (+) and alginate 20 gL -1 (*).
• Figure 8 shows the complex viscosity of EPS-3688 solutions in water at 20 gL 1 , 10 gL -1 ⁇ , 5 gL -1 ⁇ , 1 gL -1 ⁇ and 0.5 gL -1 x per compared to EPS-Pav20 gL- 1 (+) and alginate 20 gL ⁇ 1 (*).
• Figure 9 illustrates shear fluidity (viscosity as a function of shear gradient): effect of salinity on the viscosity of ESP-3707 solutions (outward curves: solid symbols; return curves: empty symbols; NaCI 0.15 M: round water: triangles), 20 gL -1 (red), 10 gL 1 (blue), 5 gL 1 (green), 1 gL 1 (black) and 0.5 gL 1 (pink).
• Figure 10 illustrates the effect of the nature of the salt on the viscosity of the solutions of EPS-3707 at 1 gL 1 in water, KSCN 1 M and NaCI 1 M (outward curves: solid symbols; return curves: empty symbols)
• Figure 11 illustrates the effect of salinity on oscillation measurements.
• Left axis elastic (full circle) and viscous (empty circle) modules
• right axis complex viscosity (triangle) as a function of the frequency of EPS-3707 1 gL -1 in water and NaCl at 0.05; 0.15; 0.5 and 1 M.
• Figure 16 illustrates the comparison between SLB of EPS solutions at 1 gL -1 in water at 25°C, 37°C and 60°C.
• Figure 15 illustrates the percentage transmission with aging time of microcrystalline cellulose suspensions at two different tube heights (dotted line: bottom of tube, 2 cm) (full line: top of tube, 5.5 cm) .
• Figure 16 illustrates the percent transmission with aging time of the 00 emulsions at two different tube heights (dotted line: bottom of tube, 2 cm) (full line: top of tube, 5.5 cm).
• Alginate (ALG) (with a mannuronate/sodium glucuronate ratio of 1.2) was supplied by Cargill (France)
• Glossomastix sp. (Strains RCC3688 and RCC3707 cited above) placed in the Pinguiophyceae, are golden microalgae isolated from St Margaret's Bay (UK);
• Pavlova strain 3438 placed in the Pavlovophyceae is a microalgae isolated from the Black Sea in Varna in Bulgaria. 1 .2 Production of EPS
• Glossomastix sp. RCC3688 was cultured in Erlen or airlift with an F/2 medium (enriched or not), at 20°C under irradiance between 40 and 300 pmolphotons/m 2 /s with a day/night cycle or continuous illumination with shaking between 0 and 120 rpm.
• the Glossomastix sp. (RCC3707) is grown in airlift condition in bottles (2 to 5 L) to compensate for its sensitivity to mechanical agitation.
• the airlift cultures are equipped with a cylindrical air diffuser connected to a network of compressed air sterilized by filtration (0.22 ⁇ m).
• the cultures are carried out at 20° C. (air-conditioned room) and illuminated by neon lights providing an irradiance of 40 pmol photons. nr 2 .s 1 .
• the strain is cultured in batch mode and in photoautotrophy with a day/night cycle of 16 h/8 h.
• the 2 and 5 L batch cultures are produced in “enriched F/2” medium and inoculated respectively with 200 and 500 mL of inoculum in the exponential phase.
• composition of the enriched F/2 medium is the same as that of the F/2 medium described by Guillard and Ryther (Studies of marine planktonic diatoms. I. Cyclotella nana Hustedt and Detonula confervacea Cleve. Can. J. Microbiol. 8: 229- 239, 1962), except for the contents of nitrogen and phosphorus sources which have been increased.
• the F/2 medium developed by Guillard and Ryther (1962) is a standard culture medium for the culture of microalgae. It consists for 1 L of artificial sea water of: 100 pL of a 10X solution of microelements, 100 pL of a 10X vitamin solution, 0.0075 g of NaNÜ3 and 0.00055 g of NaH 2 P0 4 .2H 2 0.
• the “modified F/2” medium has the same composition as the F/2 medium, with the exception of the concentrations of NaNÜ3 (1 gL ⁇ 1 ) and NaFI 2 P0 4 .2FI 2 0 (0.2 gL ⁇ 1 ).
• the new concentrations of this culture medium were determined by Villay et al. (2013) Bioresource Technology, 146, 732-735 by a stoichiometric analysis of the composition of the medium and comparison with the average molar composition of the microalgae determined by Pruvost & Cornet. C. Posten, C. Walter (Eds.), Microalgal biotechnology, “potential and production”, Walter De Gruyter GmbH and Co KG, Germany (2012). These concentrations were determined in order to reach a biomass concentration of 1 gL -1 .
• the “enriched F/2” medium has the same composition as the F/2 medium but where the concentrations of NaNÜ3 and NaH 2 P0 4 .2H 2 0 are respectively equal to 1.7 and 0.55 gL ⁇ 1 , respectively. These concentrations were determined with the same method as that used for the “modified F/2” medium, with the objective of achieving a biomass concentration of 2 gL 1 .
• the enriched F/2 medium that was used is composed for 1 L of artificial seawater of:
• composition of the artificial sea water used is:
• the solution of microelements consists of: - Na 2 EDTA 4.16 g
• the vitamin stock solution consists of: - Cyanocobalamin (Vitamin B I2 ) 0.0005 g
• the aforementioned Pavlova RCC3438 strain was cultured in a 1.4 L toric PBR, at 20° C., under a continuous irradiance of 150 pmolphotons/m 2 /s and stirring at 100 rpm, with an enriched F/2 medium.
• the pH was regulated by modifying the C0 2 level in the injected air (gas flow rate of 200 mL/min, with a C0 2 level of 0.5 to 3%).
• the rheological measurements were carried out with the AR2000 rheometer (TA Instrument, UK), using a standard size double air gap concentric cylinder geometry (aluminum, air gap 500 ⁇ m) except for the highest concentration for which a cone/plane geometry ( diameter 4cm; angle 2°; air gap 57pm) was used. All measurements were performed with a solvent trap to avoid evaporation. Flow procedures were performed at 25°C from 0.1 to 1000 s 1 (for 10 min) and from 1000 to 0.1 s 1 (for 10 min) at various concentrations in water or NaCl medium. (0.05 to 1 M) (with 200 ppm sodium azide to avoid bacteriological degradation). Oscillation procedures were performed at 25°C, 37°C or 60°C.
• the linearity domain of each EPS solution was determined before performing the frequency sweeps (from 0.001 or 0.01 to 10 Hz).
• the stress limit value (Oi im ) of the linearity domain was determined graphically.
• the Hershel-Bulkley model was applied to the flow curves to determine the threshold stress of the EPS solution.
• the viscoelastic properties of the EPS solutions were also evaluated non-destructively (without mechanical stress) using the Rheolaser Master® from Formulaction (France).
• This technique is based on a dynamic light scattering technique called Scattering Wave Spectroscopy (DWS).
• DWS Scattering Wave Spectroscopy
• a video camera is used as a detector of the backscattered waves to display an interference image called "Speckle". The dark and bright spots on the image obtained result from respectively destructive and constructive interference between the backscattered waves.
• the Brownian motion of objects depends on the viscoelastic structure of the sample, therefore, the speed of intensity fluctuations on the interference image is also different.
• the strain rate of the speckle pattern makes it possible to characterize the structural properties of the samples studied.
• a decorrelation function is used and the mean square displacement (MSD) of the product scatterers is obtained from the decorrelation curve, reflecting the average area explored by the particles at a given decorrelation time. From the MSD curve as a function of the decorrelation time, a lot of information is obtained and parameters such as the elasticity index (El) and the solid-liquid balance (SLB) are determined.
• the EI is determined as the inverse of the plate height value, and is proportional to the elastic modulus G' at the plate.
• El gives information on the evolution of the elasticity of the product with time and is calculated automatically between 2.5 ms and 1.5 s of decorrelation.
• SLB is characteristic of the ratio between the solid-like behavior and the liquid-like behavior of the product. SLB values change in the same way as tan d (ratio of G" to G') obtained in rheology in oscillation mode. SLB is obtained by the value of the slope (in logarithmic scale) at the elastic plateau of the MSD curve. More the sample is “elastic/solid”, the lower the SLB value (0 ⁇ SLS ⁇ 0.5) The higher the value, the more viscous/liquid the sample (0.5 ⁇ SLB ⁇ 1).
• alginate and EPS analyzes of Glossomastix, RCC3707 and Pavlova sp.
• RCC3438 were dissolved in 25 mL of water (containing 200 ppm sodium azide) at 0.1, 0.5, 0.75 or 1 gL -1 .
• 200 ⁇ L of latex particle solution (10% v/v, latex particle size 1 ⁇ m) was added to the polysaccharide solutions and the Brownian motion of the latex particles was studied.
• the measurements were carried out three times at 25, 37 or 60°C for 2 hours. All data are analyzed with RheoSoft Master v1.4.0.0 software.
• the results (El and SLB) are given as the average of three measurements.
• Turbiscan® Classic MA2000 is an optical analyzer from Formulaction, France. This technique is based on the variation of backscattered or transmitted light signals. Backscatter (BS) and transmitted (T) intensities are measured as a function of sample height and aging time. The size of the tube is 6 cm in height. For the analyses, we determined the percentage of transmission at the bottom of the tube (2 cm) and at the top of the tube (5.5 cm) as a function of aging time. If the percentage of transmission increases and reaches a value close to 100%, this means that settling or creaming occurs with or without flocculation or coalescence.
• BS Backscatter
• T transmitted
• microcrystalline cellulose suspensions ACROS, France, average particle size 90 ⁇ m
• EPS-Pav Pavlova EPS suspensions
• orange oil emulsions (Sigma, France) in EPS solutions was also studied.
• An orange (00) oil emulsion was prepared as follows: 2.5 mL of 00 was added to 22.5 mL of water (the water/oil ratio was 90/10 (V/V )) and homogenized with the Ultra-Turrax homogenizer (T18 Basic, IKA, France) for 5 min at speed 3 (11,000 rpm) (Table 1a).
• the stability of the 00 emulsions in pure water was checked by size measurements (Mastersizer 3000, Malvern, USA) and the size of the oil droplets (3 ⁇ m ⁇ 0.5) is stable for 15 min.
• emulsion 00 was quickly added to 5 mL of EPS solutions (at various concentrations) and rapidly homogenized by inverting the tube three times to obtain 6 mL of emulsion 00 in EPS solutions.
• Tables 1 and 1 bis show the different dispersions (the final concentration of the EPS solutions is given taking into account the dilution due to the mixing of 1 mL of emulsion 00 in 5 mL of EPS solution) and the time and the frequency of analyzes with the Turbiscan®.
• EPS-Pav emulsions have not been tested because this polysaccharide gives cloudy solutions and is not compatible with optical analysis.
• EPS solutions in water or in a saline medium have been studied by rheology in flow experiments leading to viscosity properties; or in oscillation experiments to analyze viscoelastic properties.
• the rheological behavior of EPS solutions was then compared to alginate, a polysaccharide derived from macroalgae.
• the EPS solutions of Pavlova sp. RCC3438(EPS-Pav) were analyzed by flow experiments between 0.1 and 1000 s 1 at 20 gL -1 in water ( Figure 1).
• the thixotropic character was also evaluated by a second step of 1000 at 0.1 s 1 .
• the EPS-Pav solution exhibits viscous, non-Newtonian, and weakly shear-thinning behavior.
• the EPS-Pav solution has a lower viscosity ho: 0.018 Pa.s for the EPS-Pav and 0.27 Pa.s for the alginate (the Cross model is used to determine ho).
• the EPS-3688 and EPS-3707 solutions behave like weak gels even at low concentration (1 gL -1 ) with a low threshold stress and low viscoelastic moduli.
• both EPS-3707 and EPS-3688 lead to weak gels with dynamics of the same order of magnitude.
• the relaxation time tr, or disentanglement time is 85 s for the EPS-3707 solution with an elastic modulus of 0.02 Pa and about 50 s for the EPS-3688 solution with an elastic modulus of 0.03 Pa.
• the EPS-3688 solution has slower dynamics compared to the EPS-3707 solution.
• the relaxation time is about ten times higher.
• the complex viscosities of EPS solutions in water are compared to alginate and EPS-Pav solutions in Figure 7 (EPS-3707) and Figure 8 (EPS-3688).
• EPS-3707 alginate and EPS-Pav solutions in Figure 7
• EPS-3688 Figure 8
• a strong variation in complex viscosity is also observed over the entire frequency range, whereas for alginate or EPS-Pav solutions, the complex viscosity varies very little.
• EPS solutions were prepared in NaCI medium, a lyotropic salt (strengthening hydrophobic interactions) or KSCN, a chaotropic salt (weakening hydrophobic interactions) at different concentrations to study the impact of salinity on the rheology of the solutions.
• the flow curves of EPS-3707 solutions in 0.15 M NaCl are compared to the flow curves in water in Figure 9.
• the forward (solid symbol) and return (empty symbol) curves are plotted to show the slight thixotropy.
• the viscosity of the saline solutions is increased compared to the solutions in water except for the 1 gL -1 solution for which the viscosity in 0.15 M NaCl is slightly reduced compared to the viscosity in water.
• the presence of NaCl leads to the screening of the charges present on the polysaccharides with a reduction in electrostatic interactions and a possible increase in hydrophobic interactions causing a gain in viscosity.
• Another effect of the presence of NaCl can be observed on the EPS-3707 solution at 20 gL -1 : the thixotropy disappears (the forward and reverse curves are superimposable).
• the effect on NaCI concentration was also studied on EPS-3707 at 1 gL -1 in 1 M, 0.5M, 0.15M and 0.05M NaCI with little impact on solution viscosities. It can be assumed that a low concentration of NaCl is sufficient to screen the charges.
• KSCN has an effect on the thixotropy of ESP-3707 solutions. Indeed, the thixotropy of these solutions is increased compared to the solution in water.
• the EPS 3688 study gives comparable results.
• Table 3 gives I ⁇ I at different temperatures (25, 37 and 60°C) for each polysaccharide at 1 gL -1 in water and at different concentrations for the EPS-3688 solutions (0.75; 0.5 and 0. 1 gL -1 ).
• This technique confirms the higher elastic character of EPS-3688 and EPS-3707 than EPS-Pav at 25°C. Indeed, the EI of EPS-3688 and EPS-3707 is greater than the EI of EPS-Pav.
• concentration on EI was evaluated on EPS-3688 between 0.1 and 1 gL -1 in water and at each temperature. El logically decreases if the concentration decreases like the elastic modulus G'.
• the Brownian motion of the particles depends on the viscoelastic structure of the sample and as the concentration decreases, the viscoelastic properties also decrease.
• the increase in temperature shows a difference between the EPS solutions.
• EPS-3707 and EPS-Pav an increase in temperature causes a slight decrease in EI while for EPS-3688, temperature has no effect on EI (except at 0 .1 gL -1 ).
• the decrease in EI with increasing temperature seems logical because the Brownian motion of particles accelerates with temperature. But if the EI is unchanged with temperature, it seems that the interactions leading to the weak gel structure are strong enough not to be influenced by temperature.
• the Solid Liquid Balance (SLB Balance) is obtained by the value of the slope (in logarithmic scale) at the elastic plateau of the MSD curve. If SLB ⁇ 0.5, the elastic behavior is predominant, if 0.5 ⁇ SLB ⁇ 1, the viscous behavior is predominant.
• Figure 12 compares the SLB of all EPS at 1 gL -1 at different temperatures.
• SLB 0.53
• SLB EPS-Pav and alginate clearly exhibit viscous behavior
• FIG. 13A shows an example of a graph obtained for the analysis of a suspension of microcrystalline cellulose in pure water.
• the x axis represents the height of the analysis tube, the y axis the transmission and the aging time is represented by the different colors.
• Figure 13B shows an example of a graph obtained for the analysis of the suspension of microcrystalline cellulose in a solution of alginate at 10 gL -1 in water and Figure 13C in a solution of EPS-3688 at 1 gL -1 in water.
• the differences between the three examples clearly show the stability of the suspension in a solution of EPS-3688 (even at 1 gL ⁇ 1 ). In pure water, the particles settle rapidly at the bottom of the tube and the transmission at the top of the tube reaches its maximum in a few minutes.
• the suspension of microcrystalline cellulose in a solution of EPS-3688 at 1 gL 1 is much more stable than in water and in a solution of alginate at 10 gL -1 .
• the percentage of transmission at the bottom of the tube remains constant, only a slight increase in transmission is observed at the extreme top of the tube (the maximum value is 32% after 5 p.m.), due to the start of settling.
• transmission increases from the start at the top of the tube (reaching 88% at 5:30 a.m.) and more slowly at the bottom of the tube (reaching 27% after 5:30 a.m.) confirming the rapid start of settling.
• the EPS-3688 solution is a good suspension stabilizer.
• FIG. 19A The stability of 00 emulsions with alginate (Fig. 19A), EPS-3707 (Fig. 19B) and EPS-3688 (Fig. 19C) solutions was studied using the Turbiscan® Classic MA2000 .
• Figures 14A-B-C show a high stability of the emulsions more particularly in the EPS-3688 solution: no transmission peak is observed during the whole experiment. With EPS-3707, a small peak appears around 0.7 mm after 3 hours and in alginate it appears earlier, reflecting instability.
• Figure 16 clearly shows the good stability of the emulsions with the EPS solutions (no transmission variation at the bottom (2 cm) or at the top of the tube (5.5 cm) throughout the time (40 h)). Whereas for emulsion 00 with the alginate solution, the percentage of transmission increases at the top of the tube from the first minutes. EPS-3707 and EPS-3688 are therefore good emulsion stabilizers.

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