WO2002006352A1

WO2002006352A1 - Method for preparing galactomannan oligomers

Info

Publication number: WO2002006352A1
Application number: PCT/FR2001/002288
Authority: WO
Inventors: François Delprato; Karl Heinrich Oskar Tiefenthaler; Philippe De Braeckelaer; Gilles Pruvost; Céline LEROY
Original assignee: Rhodia Chimie
Priority date: 2000-07-17
Filing date: 2001-07-13
Publication date: 2002-01-24
Also published as: AU2001276446A1; FR2811667B1; EP1301543A1; FR2811667A1; MA25828A1

Abstract

The invention concerns a method for preparing oligomers of at least a galactomannan, characterised in that it consists in subjecting a mixture comprising at least a galactomannan in solid form and water, but free of oxidising agent and acid, to an extrusion cooking treatment, whereof the specific mechanical energy ranges between 140 and 220 Wh/kg and the temperature at the product head ranges between 80 and 180 °C.

Description

PROCESS FOR THE PREPARATION OF GALACTO ANNAN ES OLIGOMERS

The present invention relates to a process for the preparation of oligomers of at least one galactomannan by treating it by cooking-extrusion. It also relates to the oligomers obtained or capable of being obtained by this process, as well as their uses.

The invention further relates to the compositions based on the above oligomers.

Galactomannans are nonionic polysaccharides extracted from the albumen of legume seeds of which they constitute the reserve carbohydrate. They are especially known and used as a texture agent and in particular for their viscosifying, thickening, stabilizing, water-retaining, and film-forming properties. Among the most widely used are guar gum, locust bean gum, and tara gum.

They are chemically neutral macromolecules, comprising a main chain consisting of D-mannopyranose units linked in position β (1-4) and substituted by D-galactopyranose units in position α (1-6).

The different galactomannans are distinguished by the proportion of D-mannopyranose and D-galactopyranose units which are represented by their mannose / galactose ratio (hereinafter M / G). Although variable from one species to another, the mannose / galactose ratio is about 1 for fenugreek, 2 for guar, 3 for tara, and 4 for locust bean.

Various industries, such as the cosmetic, dye, food, detergency, agrochemical, industrial formulations, pharmaceutical, building materials, drilling fluids industries use these polysaccharides, among others, for their texture property and in particular for thickening or viscosant, stabilizer, emulsifier, gelling agents, binder.

These polysaccharides are all the more advantageous because, by their nature, they are compatible with other compounds and therefore can be used in combination with these to produce synergistic effects, inter alia, in terms of texture. For example, locust bean gum in combination with xanthan gum can lead to gels of different strengths and more or less elastic consistencies.

Native galactomannans are highly hydrophilic polymers which, at low concentrations, lead to very viscous solutions. Depending on the intended application, this aspect may limit their use. The properties of galactomannans can be linked to their molecular mass.

For example, at different molecular weights, it is possible to obtain galactomannans whose texturing properties and in particular the thickening or viscosifying property can be adjusted. The classic routes of access to galactomannans of different molecular weights are:

- oxidative route in the presence of alkali,

- basic route in the presence of oxygen, - enzymatic route,

- acid depolymerization.

These depolymerization methods are known per se. We could refer for example to:

EP 0130946 for the oxidative depolymerization process in the presence of alkali, and for the basic route in the presence of oxygen,

- PCT / US98 / 14677, with regard to enzymatic depolymerization, and

- "Sâurehydrolyse glykozidischer Bindungen", Jozsef Szejtli, 1975, VEB Fachbuchverlag, Leipzig, for acid depolymerization.

Although widely used, these methods have drawbacks. Indeed, chemical depolymerization, whether basic or acid, leads to galactomannans of lower molecular weights. However, the resulting galactomannans require further purification in order to remove the side products formed during the process. In addition, with this type of process, obtaining galactomannans with molecular weights by weight of less than 50,000 g / mole is long and expensive. Furthermore, in certain cases, the operating conditions are such that the degradation of the galactomannan takes place before its depolymerization.

The enzymatic depolymerization which has the advantage of allowing a selective cleavage of the galactomannan (compared to the chemical process) is a process which is not economically advantageous. In addition, in some cases, it is difficult to deactivate the enzyme at the end of the reaction without degrading the depolymerized product.

It is described in WO9310 56 to prepare galactomannan oligomers by subjecting heteropolysaccharides to extrusion in the presence of an oxidizing agent or of an acid, at a temperature above 80 ° C. and at a pressure below 50 bars (5.

R

10 P). However, introduced agents which have not completely reacted must be eliminated subsequently. These agents can present drawbacks during extrusion. Thus, the oxidizing agent causes significant corrosion for the sleeves and the screw sections and therefore requires the use of expensive metallurgy.

The present invention aims to overcome the drawbacks mentioned above by proposing a process which is simple and economical to implement and in which the resulting oligomers are free of secondary products.

Another object of the present invention is to provide a process for the preparation of galactomannan oligomers continuously. These and other objects are achieved by the present invention which relates to a process for the preparation of oligomers of at least one galactomannan, characterized in that a mixture comprising at least one galactomannan in solid form and of water, but devoid of oxidizing agent and acid, to a cooking-extrusion treatment, the specific mechanical energy of which is between 140 and 200 Wh / kg and the temperature at the top of the product is between 80 and 180 ° C.

Preferably, the specific mechanical energy is between 150 and 200 Wh / kg.

The document, which is incorporated here by reference, describing the specific mechanical energy is: Meuser, F .; and van Lengerich, B. Systems analytical model for the extrusion of starches. In Thermal processing and quality of foods; Zeuthen, P.; Cheftel,

J.C. .; Jul. M .; Leniger, H .; Linko, P .; Varela, G; Vos, G., Eds .; Elsevier Applied Sci. Publ.,

London, 1984, pp. 175-179.

A subject of the invention is also the galactomannan oligomers obtained or capable of being obtained by the above-mentioned process.

Other advantages and characteristics of the present invention will become apparent on reading the description and examples which follow.

In the context of the present invention, the term "oligomer" of galactomannans means galactomannans whose viscosity is lower than that of the galactomannans introduced into the cooker-extruder. The viscosity of the product thus extruded can be measured by various methods, in particular by a Brookfield RVT 500 device (20 rpm) at 25 ° C. in a solution at 0.5% by weight of distilled water. More particularly, the ratio of the viscosities of the oligomers obtained on the starting galactomannans is less than or equal to 4/5, advantageously less than or equal to 3/5.

By adjusting the parameters of the cooking-extrusion apparatus, different ranges of viscosity and therefore different ranges of molecular weights can be obtained.

In the context of the present invention, the galactomannans can be used alone or as a mixture. Among the galactomannans, non-limiting mention may be made of galactomannans having a mannose / galactose ratio (M / G) of at most 5, and more particularly guar, carob, cassia and tara.

According to a preferred embodiment of the invention, the galactomannan is guar.

The galactomannan is advantageously in the form of a powder. The powder can be obtained by conventional grinding means such as grinding in mills of the type: - cylinder mills for powder of average particle size 100 mesh, that is to say a flour having at most 1% by mass of particles greater than 80 mesh and at most 10% by mass of particles less than 200 mesh;

- pin mills for finer grain sizes: * type mesh 200, that is to say a powder having no particles greater than 80 mesh and having at most 60% by mass of smaller particles at 200 mesh, and

° mesh type 175, that is to say a powder having at most 1% by mass of particles greater than 80 mesh and at most 75% by mass of particles less than 200 mesh.

The powder can be used as it is or after treatment with suitable enzymes such as, for example, alkaline, acidic and / or neutral proteases; of the

Iipases; phytases; alkaline, acidic and / or neutral phosphatases; amylases. The treatment with enzymes is carried out by conventional and known methods.

The particle size of said powder can fluctuate between 10 and 150 microns. In the case of treated powders, this particle size is more particularly from 20 to 60 microns, preferably from 30 to 50 microns.

Granulometry measurements can be carried out by the laser granulometry technique, using a MALVERN granulometer, sold by the company Malvern Instruments S.A.

In addition to the galactomannan (s), the mixture comprises water.

The amount of water introduced into the extruder is generally such that the amount of water represents in the mixture at least 50%, preferably at least 53%, by weight relative to the total weight of the mixture. Such a proportion of water makes it possible in particular to reduce the variations in pressures which can, when these variations are too great, make the implementation of this process difficult, if not impossible.

Preferably, this amount of water is less than or equal to 65%, preferably 62%, by weight relative to the total weight of the mixture. The mixture comprising at least one galactomannan in solid form and water, is generally produced in the cooking-extrusion processing machine (introduction in parallel). In addition, water is preferably mixed with the galactomannan before introduction into the machine (preconditioning). The preconditioning water is advantageously introduced at a temperature of the order of 90 ° C or in the form of vapor.

The water which is introduced in parallel into the extruder is preferably introduced into a module having a temperature between 50 and 70 ° C. The depolymerization of galactomannans into galactomannan oligomers according to this process does not require the presence of at least one oxidizing or acidic agent. Thus, oxidizing agents, such as in particular hydrogen peroxide, nitric acid, and their mixtures, are not introduced. It is the same for acids, such as in particular lactic acid, tartaric acid, citric acid, phosphoric acid, sulfuric acid and their mixtures.

The above mixture is then subjected to controlled conditions of temperature and pressure so that the galactomannan undergoes no degradation and only depolymerization. The temperature at the top of the product in the cooker-extruder is advantageously between 80 ° C and 180 ° C, preferably between 100 ° C and 150 ° C.

The screw speeds preferentially vary between 110 and 300 rpm and advantageously between 110 and 150 rpm.

The flow rate of pulverulent material is preferably between 18 and 30 kg / h ("wet" material, the dry material representing 90-92% by weight of the wet material), advantageously between 20 and 25 kg / h.

The residence time is variable and will of course depend on the desired viscosity and the operating conditions, in particular the cooking-extrusion apparatus used, the screw speed and the feed rate. In general, it is less than 1 minute.

If it is desired to obtain a greater depolymerization, the product thus extruded can undergo another or possibly several other passages in the cooker-extruder.

The extruded oligomers obtained according to the process of the present invention are recovered and advantageously undergo a drying step. This drying step is advantageously carried out so as to obtain a moisture content of between 8 and 12% by weight relative to the total weight of the product obtained (oligomers + water), while preventing the oligomers from degrading. Thus, this step is advantageously carried out by heating to a temperature between 30 and 60 ° C, preferably between 35 and 45 ° C.

The process of the invention is advantageously carried out continuously.

The process of the invention can be carried out in any type of cooker-extruder.

Preferably, a twin-screw extruder is used. Thus, the following devices can in particular be cited: the twin-screw models BC21, BC 45, BC72, BC82 from the company Clextral, the twin screw extruder ZSK 40 from the company Werner & Pfleiderer Gmbh, the models

Wenger X-5 and APV Baker MPF-50/25.

Preferably using the twin screw extruder (with co-rotating and co-penetrating screws) Clextral BC 45 of 66kW. The screws can comprise sections with positive action of different pitches, sections with negative pitches (counter-threads) or sections made up of mixing discs. Generally, the screws are made up of a succession of these different types of sections. The extruder is equipped with one or more modules, therefore of variable length

(each module has a length of 200mm in the case of the Clextral BC 45), more particularly the machine has a length of sheath which can vary from 600 to 1400 mm (i.e. in the case of the Clextral BC 45 the sheath consists of 3 to 7 modules). These modules are either sealed or pierced with one or more orifices (allowing in particular the introduction of materials into the extruder or degassing).

The temperature of the sheath can be regulated in particular by a heat-transfer fluid, by heating collars or induction coils or by a combined system, in particular by heating by a thermal induction system and by cooling by circulation of cold water. Preferably, the first part of this sheath, that is to say the part for supplying reagents, often materialized by the (or both) first module (s) pierced with orifices, is at a temperature between 15 and 50 ° C and the rest of the sleeves is regulated at a temperature advantageously between 50 ° C and 180 ° C, preferably between 60 ° C and 150 ° C. The temperature can vary from one module to another.

At the end of the terminal sheath is assembled a die assembly: a front plate and a generally cylindrical die. Advantageously, a knife is placed on the external face of the die which makes it possible to cut the extruded product into sections of defined length. Thus, the temperature at the top of the product is called the temperature at the end of the machine, generally at the level of the front plate, just before the die and the product outlet.

The present invention also relates to the galactomannan oligomers obtained or capable of being obtained by the process according to the invention. The invention also relates to the uses of the galactomannan oligomers obtained or capable of being obtained by the process of the invention, in the cosmetic, dyeing, food, detergency, agrochemical, industrial formulations, pharmaceuticals, building materials industries. , drilling fluids.

The invention finally relates to the compositions based on galactomannan oligomers obtained or capable of being obtained by the process of the invention, in the cosmetic, dyeing, food, detergency, agrochemical fields, those of industrial, pharmaceutical formulations , building materials, drilling fluids. Concrete but nonlimiting examples of the invention will now be presented.

EXAMPLES

Process for the preparation of guar oligomers

The cooker-extruder used is the BC 45 from Clextral co-rotating twin-screw model of 66kW with a sheath length of 1000mm (5 modules) with a negative pitch zone and 3 heating zones.

The starting galactomannan is guar gum (MEYPRO® - GUAR CSA 200/50 from the company MEYHALL).

The cooking-extrusion conditions are collated in the following table (1):

Table (1) E.M.S. means specific mechanical energy.

The products obtained after extrusion are dried in an oven at 40 ° C. in order to stabilize them at a humidity of between 8 and 12% by weight.

Samples 1, 2 and 3 are ground and only the fraction less than 100 μm is used by reference to the particle size of the control sample. Viscosity is measured at using a Brookfield model 500 RVT device under the following conditions: 0.5% solution in distilled water, dispersion with ultraturax for 20 seconds at 9500 rpm, the viscosity being measured at 20 rpm at 25 ° C after 24 hours.

The results are collated in the following table (2):

Table (2)

For comparison, samples 4 and 5 were tested.

- sample no. 4, same parameters as sample no. 1 but water introduced at the rate of 20.1 liters / h (water thus represents 48% by weight in the mixture relative to the total weight of the mixture) and presents an EMS of 230 Wh / kg, gives a viscosity product of 405 mPa.s. - sample no. ^c 5, same parameters as sample no. 1 but has an EMS of 268 Wh / kg, gives a product with a viscosity of 515 mPa.s.

Claims

1. Process for the preparation of oligomers of at least one galactomannan, characterized in that a mixture comprising at least one galactomannan in solid form and water, but devoid of oxidizing agent and acid, is subjected, to a baking-extrusion treatment, the specific mechanical energy of which is between 140 and 200 Wh / kg and the temperature at the top of the product is between 80 and 180 ° C.

2. Method according to claim 1, characterized in that the specific mechanical energy is between 150 and 200 Wh / kg.

3. Method according to any one of claims 1 or 2, characterized in that the galactomannan is in the form of powder.

4. Method according to any one of claims 1 to 3, characterized in that the galactomannan is guar.

5. Method according to any one of claims 1 to 4, characterized in that the amount of water introduced into the extruder is such that the amount of water represents in the mixture at least 50%, preferably at least 53 %, by weight relative to the total weight of the mixture.

6. Method according to any one of claims 1 to 5, characterized in that the amount of water is less than or equal to 65%, preferably 62%, by weight relative to the total weight of the mixture.

7. Method according to any one of claims 1 to 6, characterized in that the mixture comprising at least one galactomannan in solid form and water is produced in the cooking-extrusion treatment machine (introduction in parallel).

8. Method according to claim 7, characterized in that water is mixed with the galactomannan prior to introduction into the cooking-extrusion treatment machine.

9. Method according to any one of claims 1 to 8, characterized in that the water which is introduced in parallel into the cooker-extruder is introduced into a module having a temperature between 50 and 70 ° C.

10. Method according to any one of the preceding claims, characterized in that the temperature at the top of the product in the cooker-extruder is between 100 ° C and 150 ° C.

11. Method according to any one of claims 1 to 10, characterized in that the supply rate of "wet" material is between 18 and 30 kg / h, advantageously between 20 and 25 kg / h.

12. Method according to any one of claims 1 to 13, characterized in that the oligomers thus obtained undergo one or more other passages in the cooker-extruder.

13. Method according to any one of claims 1 to 12, characterized in that it further comprises a step of drying the oligomers thus extruded.

14. The method of claim 13, characterized in that the drying step is carried out so that the humidity of the oligomers thus dried is between 8 and 12% by weight.

15. Galactomannan oligomers obtained by the process according to any one of claims 1 to 14.

16. Use of galactomannan oligomers according to claim 15 in the cosmetic, dyeing, food, detergency, agrochemical, industrial formulation, pharmaceutical, building materials, drilling fluids industries.

17. Composition based on galactomannan oligomers according to claim

15, in the cosmetic, dyeing, food, detergency, agrochemical, industrial formulation, pharmaceutical, building materials, drilling fluids fields.