EP2408310A2

EP2408310A2 - Method for reducing protein fouling on equipment for processing a protein fluid derived from milk

Info

Publication number: EP2408310A2
Application number: EP10715956A
Authority: EP
Inventors: Romuald Guerin; Gilles Ronse; Pascal Debreyne; Guillaume Delaplace
Original assignee: Institut National de la Recherche Agronomique INRA
Current assignee: Institut National de la Recherche Agronomique INRA
Priority date: 2009-03-20
Filing date: 2010-03-18
Publication date: 2012-01-25
Also published as: WO2010106296A2; FR2943220B1; WO2010106296A3; FR2943220A1

Abstract

The present invention relates to a method for reducing protein fouling in equipment for processing a protein fluid derived from milk. The method according to the invention includes the step of subjecting said protein fluid to a variable low-frequency electromagnetic field on at least one section of a fluid circulation channel of said processing equipment.

Description

METHOD FOR REDUCING THE PROTECTIVE ENCRYPTION OF A SYSTEM FOR TREATING A MILK DERIVED PROTEIN FLUID

Technical field of the invention

The invention relates to the field of fouling of installations used for the treatment of protein fluids.

State of the art The formation of protein deposits is the main cause of fouling of milk processing plants and milk products. This protein fouling reduces the performance, especially the yield, of the processes, affects the quality of the end products and imposes regular operations of cleaning of the installations requiring the total stop of the production. Moreover, it can constitute a favorable environment for bacterial growth thus compromising the sterility and the safety of the final products.

Protein fouling is generally caused by thermal denaturation and aggregation of the proteins contained in the treated fluid. It is mainly observed at the level of heat exchangers. Regarding the treatment of cow's milk and its derived fluids, it has been shown that protein fouling results from phenomena of thermal denaturation, aggregation and adhesion of proteins, mainly β-lactoglobulin. Under the effect of a high temperature - generally greater than 70 ^° C. - β-lactoglobulin undergoes a conformational change permitting the exposure of sulfhydryl groups (Visser and Jeurnink, 1997, Experimental Thermal and Scientific Science, 14, 407- 424). These sulfhydryl groups, very reactive, generate inter-protein disulfide bridges leading to the formation of protein aggregates. These aggregates consist of several types of milk proteins, in particular, proteins belonging to the families of lactoglobulins, lactalbumin and casein. However, the phenomenon initiating fouling has not been clearly established. It would be either the formation of an initial layer of denatured proteins or that of protein aggregates on the surface of the pipes. (Viser and Jeurnink, 1997, Experimental Thermal and Fluid Science, 14, 407-424, Bansal et al., 2006, Comprehensive Reviews in Food Science and Food Safety, 5, 27-33).

It has been shown that the protein fouling deposit formed during heating of the milk at a temperature of between 70 ^° C. and 110 ^° C. comprises from 50% to 70% by weight of proteins, from 30% to 40% by weight. of minerals and from 4% to 8% by weight of lipids, the percentages by weight being expressed relative to the dry weight of said deposit (Bansal et al., 2006, Comprehensive Reviews in Food Science and Food Safety, 5, 27-33) Factors enabling the formation and stabilization of protein deposition have not been clearly established. Some authors have shown that this deposition is stabilized by the presence of ions which would strengthen the adhesion forces between the proteins of the aggregates (Daufin et al., 1987, Lait, 67, 339-364). In contrast, other authors have shown that a high concentration of ions makes it possible to reduce protein fouling in the heat exchangers used during pasteurization or high temperature milk (UHT) erection operations ( Christian et al., 2002, Trans IchemE, 80, 231-239).

In view of the health and economic consequences of protein fouling of the facilities, several ways to reduce protein fouling have been considered. Yoon and Lund (1994, Journal of Food Science, 59, 964-969) have proposed a method of subjecting the milk to a 1500 Gauss magnetic field before entering a heat exchanger. However, they have found that this method is inefficient for prevent clogging of the heat exchanger.

More generally, the methods of reducing protein fouling cited in the prior art are based on the use of chemicals.

Thus, Hoffmann and Van Mil (1997, Journal of Agricultural and Food Chemistry, 45, 2942-2948) have shown that the addition of an agent capable of blocking thiol groups such as N-ethylmaleimide (NEM) makes it possible to limit the formation of covalent protein aggregates in a solution of β-lactoglobulin brought to a high temperature. International application WO 2006102051 describes the use of fouling inhibitors chosen from the group consisting of hydroxypropylcellulose, methylcellulose and methylhydroxypropylcellulose.

WO 2004104271 discloses a method for reducing protein fouling by forming a silicate compound coating on the surfaces of the plant that are in contact with the fluid derived from the milk.

However, while these methods may be effective, the use of such chemical agents in or in contact with milk-derived fluids for the food industry may not meet current food safety regulations. Currently, there is therefore a need for methods for reducing protein fouling in the treatment of milk-derived fluids which are alternatives to the methods described in the state of the art.

SUMMARY OF THE INVENTION The present invention relates to a method for reducing protein fouling in a plant for processing a protein fluid derived from milk.

In a preferred embodiment, the method according to the invention comprises the step of subjecting said protein fluid to a variable electromagnetic field of low frequency on at least one section of a fluid flow line of said treatment plant.

In a preferred embodiment, the variable magnetic field applied to the protein fluid according to the present invention is characterized in that it has: (i) a frequency of about 0.5 to 100 kHz and

(ii) a low intensity magnetic component

In a particular embodiment, said variable low frequency electromagnetic field is an electromagnetic field with discontinuous variations.

In a preferred embodiment, said variable electromagnetic field is generated by an electrical apparatus comprising (i) a variable voltage generator device and (ii) at least one electrical coil wound around a fluid flow conduit section of the treatment facility.

Another object of the present invention is the use of an electrical device generating a variable low frequency electromagnetic field to reduce the protein fouling of a plant for processing a protein fluid derived from milk.

A further object of the invention is a facility for treating a fluid derived from reduced protein fouling milk.

FIG. 1 shows an example of a plant for processing a protein fluid derived from milk according to the invention. This plant comprises, from upstream to downstream, a tank (1), a first heat exchanger (preheater) (2), a plate heat exchanger (driver V7) (3) and a tubular heat exchanger cooling (cooler) (4). The different units of the installation are connected by fluid flow lines. The electrical apparatus generating the variable electromagnetic field (device) (5) is positioned on the pipe section which connects the tank to the first heat exchanger. It comprises 4 capacitive inductive coils each connected by one of their ends to the voltage generator.

FIG. 2a is a histogram showing the measured fouling deposition mass for each plate of the heat exchanger (driver V7) of the installation of FIG. 1 during the treatment of a WPC solution when the process according to the invention is applied (with electric appliance, light bars) and when not applied (without electric appliance, dark bars). Abscisses: plate number of the V7 heat exchanger. Ordinate: Clogging deposit mass in grams.

FIG. 2b is a histogram showing the measured fouling deposit mass for each plate of the heat exchanger (driver V7) of the installation of FIG. 1 during the treatment of a raw milk when the process according to the invention is applied (with electric appliance, light bars) and when not applied (without electrical appliance, dark bars). Abscisses: plate number of the V7 heat exchanger. Ordinate: Clogging deposit mass in grams.

Figure 3 shows the resistance curves to the fouling of the installation 1 as a function of time during the treatment of a raw milk (squares) and a solution WPC (round) when the process according to the invention is applied (with electric appliance, round and dark squares) and when not applied (without electrical appliance, round and light squares).

Abscisses: Time in minutes, ordinates: resistance to fouling in m ² .K / W.

FIG. 4a is a photograph obtained by scanning electron microscopy (SEM) (x400 magnification) of a protein fouling deposition fragment taken from the heat exchanger V7 resulting from the treatment of a WPC solution in the installation of Figure 1 when the method according to the invention is not applied.

FIG. 4b is a photograph obtained by scanning electron microscopy (SEM) (× 400 magnification) of a protein fouling deposition fragment taken from the heat exchanger V7 resulting from the treatment of a WPC solution in the installation of Figure 1 when the method according to the invention is applied.

FIG. 5a is a histogram showing the residual fouling deposition mass for each plate of the exchanger (3) after cleaning with sodium hydroxide (2% - 80 ^° C. - 40 min) and with nitric acid (1, 5% .- 80 ⁰ C - 30 min) in the case where the WPC solution has been treated in the presence of the process according to the invention (with electrical apparatus, clear bars) or in the absence of the process according to the invention (without electrical apparatus , dark bars). Abscisses: plate number of the V7 heat exchanger. Ordinate: Clogging deposit mass in grams.

FIG. 5b is a histogram showing the residual fouling deposition mass for each plate of the V7 exchanger after cleaning with sodium hydroxide (2% - 80 ^° C. - 40 min) and with nitric acid (1.5% -80 ^° C. - 30 min) in the case where the raw milk has been treated in the presence of the process according to the invention (with electrical apparatus, clear bars) or in the absence of the process according to the invention (without electrical generating apparatus, dark bars). Abscisses: plate number of the V7 heat exchanger. Ordered: Fouling deposit mass measured after cleaning in grams.

Detailed description of the invention

The present invention relates to a method for reducing protein fouling in a plant for processing a protein fluid derived from milk.

The method according to the invention is of simple implementation and applicable to any treatment facility. It does not require a specific adaptation of said installation. It has the advantage of not requiring the addition, in the fluid, of a chemical product that may not meet the regulations in force regarding food safety. The method according to the invention is based on the application of a low-frequency variable electromagnetic field to the milk-derived protein fluid on at least one fluid flow line section of the treatment plant.

Surprisingly, the applicants have shown that subjecting a fluid derived from milk to a variable low frequency electromagnetic field on at least one section of the fluid flow line of the treatment plant significantly reduces the mass of the fouling deposit. downstream of the section where the electromagnetic field is generated. In addition, the applicants have also shown that the residual fouling deposit has a very characteristic structure. When the fluid is subjected to a variable electromagnetic field, the fouling deposit has a more porous structure with a large pore size. Consequently, it is easier to eliminate during the cleaning operations than the deposition of fouling formed in the absence of the variable electromagnetic field, whatever the cleaning method used.

By "easier to eliminate" is meant that the step of cleaning the installation is faster and / or requires a smaller volume of cleaning solution.

Without being bound by any theory, the applicants believe that the application of a variable low frequency electromagnetic field disturbs the intermolecular interactions involved in the formation and adhesion of protein aggregates. The variable electromagnetic field would therefore have the effect of disturbing the formation and the growth of the fouling deposit by reducing the intermolecular bonding forces.

In a preferred embodiment, the method for reducing protein fouling of a milk-derived protein fluid treatment plant comprises a step of subjecting said protein fluid to a variable low-frequency electromagnetic field on a proteinaceous fluid. at least one section of a fluid flow line of said treatment plant.

For the purposes of the invention, the term "process for the reduction of protein fouling" is intended to mean a method making it possible to reduce the total mass of the fouling deposit and / or to modify the structure of the fouling deposit on at least one part of the installation located downstream of the section where the variable electromagnetic field is applied. The reduction of the fouling obtained by the process according to the invention is illustrated in the examples of the present application by comparing (i) the properties of the fouling deposit obtained during the treatment of a protein fluid when the process according to the invention the invention is applied with (ii) the properties of the fouling deposit obtained during the same treatment of a protein fluid but without application of the method according to the invention. To determine whether there is a reduction in protein fouling, it is possible, for example, to compare the total mass of the protein fouling deposits (i) and (ii) with a characteristic zone of the installation. If the mass of the protein fouling deposit (i) is less than 95% of the mass of the fouling deposit (ii) then it is considered that there is a reduction of fouling. The masses of fouling deposits can be measured for example for a plate heat exchanger located downstream of the section where the variable electromagnetic field is to be generated by weighing its plates before and after fouling. This method is illustrated in Example 1 of the present application. It is also possible to compare the structures of fouling deposits (i) and (ii), for example, by scanning electron microscopy as illustrated in Example 3. It is considered that there is a reduction in fouling if the fouling deposit (i) has a less compact or more porous structure than that observed for the fouling deposit (ii). The term "treatment plant" means any facility for treating a protein fluid derived from milk. This facility may be an installation used for experimental laboratory, pilot plant or industrial installation purposes. The treatment plant within the meaning of the invention comprises at least one fluidic circulation line and, preferably, at least one heat exchanger. The term "heat exchanger" means a flow area delimited by equipment walls where the fluid undergoes a heat exchange.

"Treatment" is understood to mean any physicochemical operation leading to a modification of the initial state of the fluid derived from milk. The term treatment is therefore to be taken in its broadest sense. By way of nonlimiting illustration, a physico-chemical operation may be an operation for heating, sterilizing, pasteurizing, filtering, skimming, drying, cooking, texturing or adding one or more compounds. chemical.

The term "fluid fluid derived from milk" means any fluid comprising one or more proteins derived from a milk. By way of nonlimiting illustration, serum proteins such as caseins, lactoglobulins and lactalbumin may be cited as milk proteins. These proteins can be recombinant or non-recombinant. Thus the milk-derived protein fluids include whole milks, partially or completely defatted milks, whey, concentrated solutions of milk proteins such as WPC solutions, milk-based food preparations, the list not being limiting.

The term "electromagnetic field" means a field resulting from the combination of an electric field and a magnetic field. The electromagnetic field also includes electric fields and magnetic fields within the meaning of the invention.

The term "variable electromagnetic field" is understood to mean a field that is not constant over time, that is to say whose intensity and / or orientation varies over time. "Low frequency" is understood to mean a frequency of less than 5.10 ² kHz. The variable electromagnetic field may be generated by any suitable device known to those skilled in the art. According to the invention, said device must be capable of generating a variable electromagnetic field within the fluid fluid derived from milk through the wall of the circulation pipe without impairing the operation and environment of the installation In general, an electromagnetic field of low intensity that is to say whose magnetic component is of the order of 10 ^{~ 4} to 10 ^{~ 1} tesla is sufficient to reduce protein fouling. The maximum value for the intensity of the average electromagnetic field to be generated according to the invention has not been determined, but it goes without saying that it is preferable to generate an electromagnetic field with a mean intensity that is sufficiently low so as not to disturb the environment and be neutral vis-à-vis operators.

On the other hand, it is necessary that the frequency of variation of the electromagnetic field is sufficiently high to disturb the intermolecular interactions and thus reduce the protein fouling. Nevertheless, a frequency of the order of 10 ² kHz is generally sufficient.

In some embodiments, the method according to the invention, the frequency of the electromagnetic field is at least about 0.5 kHz and at most about 100 kHz. A frequency of at least about 0.5 kHz is understood to be at least about 0.5 kHz, 10 kHz, 15 kHz, 20 kHz, 25 kHz, 30 kHz, 35 kHz, 40 kHz, 45 kHz. A frequency of not more than about 100 kHz means a frequency of not more than about 50 kHz, 55 kHz, 60 kHz, 65 kHz, 70 kHz, 75 kHz, 80 kHz, 90 kHz, 100 kHz.

For the purposes of the invention, the term "approximately" defines an interval of ± 10% around a given value. Thus, when a frequency of about 40 kHz is mentioned, this means that the frequency belongs to the range from 36 kHz to 44 kHz. Thus, in a preferred embodiment, the variable electromagnetic field applied to the protein fluid according to the present invention is characterized in that it has:

(i) a frequency from about 0.5 to about 100 kHz and

(ii) a low intensity magnetic component

Without being bound by any theory, the applicants believe that discontinuous electromagnetic fields disrupt intermolecular interactions more strongly than do electromagnetic fields whose intensity and / or orientation vary continuously over time.

Thus, in a particular embodiment, said variable low frequency electromagnetic field is an electromagnetic field with discontinuous variations. The term "electromagnetic field with discontinuous variations" means a variable electromagnetic field whose intensity and / or orientation varies very abruptly (in other words almost instantaneously) over time. For example, pulsed (or pulse) electromagnetic fields are fields with discontinuous variations since their intensities vary almost instantaneously from a zero value to a maximum value. The occurrence of the pulses is fixed by the frequency of the electromagnetic field.

The variable electromagnetic field can be generated by an electrical apparatus. Preferably, this electrical apparatus generates a variable electromagnetic field according to one of the principles of electromagnetic induction well known to those skilled in the art. (G. BRUHAT Chapter XXXII course of general physics Electricity 8th edition Masson et Cie Editors). This apparatus may include (i) a variable voltage generating device and (ii) one or more inductors. The inductors may consist of wires, rods or conductive plates that are arranged around or on either side of a section of fluid flow conduit of the treatment plant. The inductors are electrically isolated from the pipe on which they are arranged and are each connected by at least one end to the variable voltage generator.

The inductors are insulated, and are applied outside the pipe. Inductors do not behave like electrodes. The variable voltage generating device is in the sense of the invention an electrical or electronic circuit delivering a variable voltage. It can have several outputs depending on the number of inductors connected to it. The electrical device may consist of a variable voltage generator or comprise several voltage generators, the essential fact being that the variable voltage generator device supplies the one or more inductors with a voltage capable of generating the desired electromagnetic field. Indeed, the nature of the variable voltage supplying the inductors condition the nature of the variable electromagnetic field generated.

The variable voltage may correspond to an alternating current or a variable DC current. By variable DC current is meant a variable current of constant sign.

The voltage signal of the delivered current may be of any shape, for example square, impulse, triangular or sinusoidal. The person skilled in the art, by virtue of his general knowledge, will be able to determine the characteristics of the variable voltage generator device capable of inducing the desired electromagnetic field.

By way of nonlimiting illustration, a pulsed electromagnetic field with a frequency of 20 kHz can be generated by means of a pulsed generator delivering a pulsed voltage of 20 kHz

As previously stated, it may be advantageous for the electromagnetic field to have discontinuous variations to greatly disturb the intermolecular interactions. Such an electromagnetic field within the meaning of the invention can be generated, inter alia, if the inductors of the electrical apparatus are powered by a discontinuously variable voltage such as step voltages or pulsed voltages.

Thus, in some embodiments of the method, the electrical apparatus according to the invention comprises a variable voltage generator supplying the inductors with a voltage selected from the step voltages and the pulsed voltages.

For the purposes of the invention, a step voltage is a voltage whose value varies almost instantaneously between different levels. The bearings may be of the same sign or of opposite signs. As an example of a step voltage, there may be mentioned the square-shaped voltages that are worth a constant value (i) during a first part of the period and a value (ii) different from the constant value (i) during the second part of the period. Modulation of the frequency of the delivered signal can increase the disturbing effect of the intermolecular interactions.

Thus, in certain embodiments of the method, the variable voltage supplying the inductors is modulated in frequency. Depending on the inductors used, a pulsed or square voltage having a peak-to-peak value ranging from about 1 V to about 60 V and a frequency between 0.5 kHz and 100 kHz is capable of generating a variable electromagnetic field capable of to effectively reduce protein fouling.

In a preferred embodiment, an inductor is an electrical wire that can be wound without overlapping around the conduit so as to form an electrical coil.

Thus, in a preferred embodiment of the method, said variable electromagnetic field is generated by an electrical apparatus comprising (i) a variable voltage generating device and (ii) at least one electrical coil wound around a circulation line section. flow of the treatment plant. When the appliance includes several electrical coils, it is preferable that the coils do not touch each other. It is therefore necessary to leave a space of at least one centimeter between said coils when they are arranged on the fluid flow line.

In some embodiments of the method, the electrical apparatus comprises one or more coils each connected at both ends to the variable voltage generating device.

These coils correspond to induction coils (or magnetic induction coils). The electrical device may comprise from 1 to 10 coils, preferably from 1 to 4 coils. The induction coils can be powered by the same voltage signal or by different voltage signals. They can work in phase or out of phase. Those skilled in the art will be able to use, for example, one of the commercial devices of the ScaleBlaster® range marketed by Clearwater Enviro Technologies. Depending on the dimensions of the treatment plant, the skilled person will determine the appropriate device among the available devices. By way of example, reference may also be made to application EP0357102, which describes an adaptable device for implementing the method according to the invention.

In other embodiments, the electrical device comprises at least two electrical coils which are connected to the variable voltage generating device each by only one of their two ends. Said coils then correspond to capacitive induction coils. The electrical device may comprise from 2 to 10 coils, preferably from 2 or 4 coils.

The spacing between two capacitive induction coils can vary from a few centimeters to a few tens of centimeters. Greater spacing can interfere with the generation of the variable electromagnetic field. By way of illustration and not limitation, patents FR 2643651 and FR 2607574 describe an electrical apparatus suitable for the process according to the invention and comprising so-called capacitive induction coils. Moreover, the skilled person can use a commercial device such as the KaIk Max® IT2 device from the company MAXX Tech or D-CALC® devices from the company Gottschalk Industries SA. Depending on the size of the treatment plant, those skilled in the art will be able to determine the appropriate apparatus among the available devices. It should be noted that the inductors of the KaIk Max® IT2 device are powered by a square voltage.

In some embodiments, the electrical apparatus includes both at least one induction coil and at least two capacitive induction coils. Although in some cases it is possible to arrange the coils on a metal pipe such as a galvanized pipe section, galvanized, copper, stainless steel, it is preferable to arrange the coils on a pipe of insulating material such as the PVC.

As illustrated above, those skilled in the art can either (i) use a suitable electrical appliance commercially available or (ii) develop an electrical appliance suitable for the process according to the invention, for example inspired by teaching of the aforementioned patent documents and using general knowledge of electromagnetism.

In a preferred embodiment of the method, the electrical apparatus according to the invention comprises:

(i) a variable voltage generator delivering a voltage with discontinuous variations, possibly modulated in frequency, and

(ii) at least two electrical coils each connected by only one of their ends to the variable voltage generator.

Protein fouling occurs mainly in areas of the facility where the protein fluid derived from the milk is carried or circulates at a high temperature. For the purposes of the invention, an elevated temperature is a temperature capable of inducing the denaturation of proteins of a protein fluid. With regard to milk proteins, a high temperature is a temperature greater than about 70 ^° C.

Accordingly, the method according to the invention is mainly adapted to reduce the protein fouling of a milk-derived fluid treatment plant comprising at least one heating heat exchanger.

Thus, in a preferred embodiment, said installation comprises at least one heating heat exchanger.

Heating heat exchanger means a heat exchanger capable of increasing the temperature of the fluid derived from milk under certain conditions of use. As illustrative and not limiting, heat exchangers heating include tubular heat exchangers and plate heat exchangers. In some embodiments, said installation comprises at least one plate heat exchanger. It should be noted that the effect of reducing the protein fouling generated by the process according to the invention is detectable downstream from the pipe section on which the electrical apparatus generating the variable electromagnetic field is located, at the level of the zones of the installation where the fluid is heated or circulates at an elevated temperature. By way of nonlimiting illustration, said zones comprise fluidic circulation lines, heated heat exchangers, chambering reactors, cooking reactors, heated evaporators, atomizing dryers. A treatment plant according to the invention may comprise one or more zones mentioned above.

Applicants have shown that the application of the variable electromagnetic field makes it possible to reduce protein fouling in the flow volume but also in the areas of the installation located downstream of the section where the variable electromagnetic field is applied, for example several meters or even several tens of meters of pipes.

Indeed, the recovery time of the initial properties of the fluid (that is to say its properties before treatment by the variable electromagnetic field) is generally much greater than its residence time in the installation.

Thus, in a particular embodiment, the electrical generating device of the variable electromagnetic field must be located near the entrance of the installation that is to say just downstream of the feed zone or fluid injection of the treatment plant.

In such a configuration, the electromagnetic field is generated upstream of all the areas of the treatment plant where the fluid is heated or circulates at a high temperature. This can make it possible to reduce the protein fouling of all of said zones.

It is also possible to arrange the current-generating electrical device on any pipe section of the installation located upstream of the zone or zones where it is desired to reduce protein fouling provided that the temperature of the outer wall of said section is not greater than the operating limit temperature of said device. In the case of use of a commercial apparatus, a person skilled in the art can refer to the technical note to become acquainted with the limit temperature of operation.

For treatment plants comprising a plurality of zones where the fluid is carried or circulates at an elevated temperature and / or for installations in which the residence time of the fluid is high, it is possible to install at least two electrical generators variable electromagnetic field in order to achieve a higher overall effect of reducing fouling. The electromagnetic fields may be identical or different, the important thing being that they verify the characteristics mentioned above.

Thus, in some embodiments, the method according to the invention comprises the step of subjecting said protein fluid to a variable electromagnetic bass field. frequency generated on at least two distinct sections of fluid flow conduit of said treatment plant.

Preferably, said sections are positioned upstream of a heating heat exchanger. Although the application of a variable electromagnetic field reduces the protein fouling of the milk-derived fluid treatment plant, it may still be necessary to regularly clean the plant in order to eliminate the deposition. residual fouling formed.

Thus, in certain embodiments, the method according to the invention comprises the additional step of eliminating the fouling protein deposit formed in the treatment plant.

To eliminate the fouling protein deposit, the skilled person can use a standard procedure of the state of the art. For example, after stopping the operation of the treatment plant and eliminating the residual protein fluid, the skilled person can circulate in the installation two washing solutions, a caustic solution such as a sodium hydroxide solution and a solution. acid solution such as a nitric acid solid followed by a rinsing step with water. It goes without saying that those skilled in the art will choose the cleaning and rinsing solutions according to the characteristics of the installation, in particular the nature of the materials constituting it. As stated above, the fluid fluid derived from milk is a fluid comprising at least one serum protein of milk. In some embodiments, the milk-derived protein fluid is selected from the group consisting of reconstituted milk protein solutions, whey solutions, milk, and milk food preparations.

For the purposes of the invention, the term milk refers to any milk derived from a mammal. Preferably, it is a milk that can be used for the production of food products intended for humans and animals. By way of non-limiting illustration of milks which can be used in the food industry, mention may be made of cow's milk, buffalo milk, yak milk, camel's milk, sheep's milk, goat's milk and milk. of donkey, and mare's milk.

Milk food preparation or derived from milk, any liquid or semi-liquid product comprising a derivative of milk that is used for the preparation of food for humans or animals.

By way of illustration and without limitation, such foods include concentrated milks and dairy powders as well as dairy drinks, yogurts, cheeses, dessert creams, ice creams in which the milk raw material is combined with various suitable agents including among others, flavorings, dyes and texturizing agents.

As an illustration and not limitation, it can be cited as milk drinks yogurt to drink, skimmed milks, semi-skimmed or whole, UHT or pasteurized possibly flavored. In a preferred embodiment, the milk-derived protein fluid treatment facility is a treatment plant for use in the manufacture of a milk-derived food.

By way of illustration and not limitation, it may be mentioned facilities for skimming, pasteurization or high temperature erection of milk.

Among the many advantages of the method according to the invention, it may be mentioned that it may allow, inter alia:

(i) to operate the heat exchangers at their maximum capacity over a longer period of time which increases productivity; (ii) reduce the energy costs associated with fouling deposition; and (iii) reduce the frequency of cleaning, which both ensures the safety of the installations and reduces the environmental impact. This point increases the service life of the installation and reduces maintenance costs.

A further object of the invention is a facility for treating or transforming a fluid derived from reduced protein fouling milk. In a preferred embodiment, said treatment facility comprises

(i) means for supplying or injecting the protein fluid (ii) a heating heat exchanger

(iii) an outlet means for the treated or transformed protein fluid

(iv) a plurality of fluidic flow conduits for connecting the different parts of the treatment plant and,

(v) an electrical device generating a variable low frequency electromagnetic field, said device being placed at least a section of a fluid flow conduit of the installation

The installation according to the invention is intended for the food industry. These fluidic flow lines are made of stainless steel, plastics or have an internal coating suitable for the processes of the food industry. Furthermore, said installation may also include one or more devices for performing a treatment operation such as a heating operation, sterilization, pasteurization, filtration, skimming, drying, atomization, cooking , texturing or adding one or more chemical compounds.

The plant according to the invention is also characterized in that a protein fluid derived from milk for food use is circulating in its fluidic circulation lines. The present invention is also illustrated by the examples presented below, without being limited thereto.

EXAMPLES

1. MATERIALS AND METHODS a. Description of the installation

The treatment plant comprises, from upstream to downstream, a tank (1), a first heat exchanger (preheater) (2), a plate heat exchanger (driver V7) (3) and a cooling heat exchanger (cooler) (4). The different units of the installation are connected by fluidic circulation lines The electrical apparatus generating the variable electromagnetic field (device) (5) is positioned on the pipe section which connects the tank to the first heat exchanger. It comprises 4 capacitive inductive coils each connected at one end to the pulse current generator (FIG. 1). The pipe section equipped with the coils is coated with a sheath which electrically isolates the pipe wall and the coils.

b. Solutions used

The fouling experiments were carried out for two protein fluids derived from milk: raw cow's milk and WPC solution.

The WPC solution was prepared by resuspension in water of a whey protein concentrate (PROTARMOR 750, ARMOR PROTEINS). This concentrate comprises at least 75% by weight protein, 5% fat, 13% lactose and 6% moisture. The β-lactoglobulin and α-lactalbumin respectively represent approximately 63% and 1 1% by weight of the total protein fraction. The final WPC solution comprises 1% (w / w) concentrate c. Implementation of the fouling reduction process

The electrical device used is the KaIk Max® IT2 device marketed by MAXX Tech. It comprises (i) a variable voltage generator and (ii) four capacitive induction coils. The 4 coils are wound in pairs in the same direction but in an opposite direction on a non-metallic pipe of diameter 8 mm in the cold zone of the installation (preheater inlet 4 ^< € - Fig. 1). Each coil is connected at one end to the variable voltage generator. The length of the winding is 23 cm for each of the coils. The peak-to-peak applied voltage (peak voltage) is 28V at a frequency of 13.7, 20 or 28kHz. The voltage supplying the inductors is a square voltage of -14 V and + 14 V bearings and a frequency set at 13.7 kHz, 20 kHz or 28 kHz. The voltage applied peak to peak (maximum voltage) is therefore 28V. 2. EXAMPLE 1 Measurement of the mass of the fouling deposit of the V7 heat exchanger

at. Protocol Before implementing the treatment of the fluid (raw milk or WPC solution) according to the experimental conditions "with" and "without" the electrical device, the plates of the plate heat exchanger V7 (3) are weighed, which allows determine their mass (i) before fouling (clean plates). After the fluid treatment has been carried out, the plates have again weighed, which makes it possible to determine their mass after fouling. We can deduce from this the mass (ii) of deposit on the difference of masses (i) and (ii), the fouling deposit mass is deducted for each plate of the exchanger. It is then possible to draw a histogram of distribution of the deposit within this exchanger.

b. Results The use of the process according to the invention makes it possible to significantly reduce the mass of the protein fouling deposit present on the hot surfaces by approximately 35% after 5h30 of test and by 15% after 4h15, respectively for the WPC solution. (Fig. 2. a) and raw milk

(Fig. 2.b) (see Table 1).

It is worth noting a difference in the reduction of fouling masses on hot surfaces in the case of the treatment of serum protein solution (35%) and raw milk

(15%). This difference is explained by a reduced processing time for raw milk, namely

4:15 instead of 5:30 for the WPC solution.

An extrapolation of the kinetics of deposition of the raw milk at 5:30, obtained with and without a device, would lead to a mass difference of the fouling deposit close to 30%. This value is in perfect adequacy with that obtained during the heat treatment of the serum protein solution.

3. EXAMPLE 2: Resistance to fouling

at. Method of measuring the resistance to fouling

When there is fouling, it is found that it is necessary to increase the thermal power supplied to maintain the desired thermal program. It is therefore possible to follow the clogging of the exchanger by reporting over time the evolution of the overall heat transfer coefficient or its normed value by the overall heat transfer coefficient of the clean exchanger. It is also customary to represent the degradation of the thermal performance of an exchanger by the evolution of the fouling resistance over time. This quantity corresponds to the inverse of the heat transfer coefficient. b. Results

The fouling resistance is reduced by 25% and 16% respectively for the WPC solution and the raw milk. This gap leads to an energy saving of 4.5 to 6% (Fig. 3). After 4M of treatment, the deviations of the fouling resistances obtained with and without the device are 19% and 16%, respectively for the raw milk and the serum protein solution.

EXAMPLE 3 Structure of the Protein Clogging Deposit

at. Protocol

Samples of fouling deposits were taken from the V7 exchanger plates and observed by scanning electron microscopy (x400 magnification).

b. Results

The structure of the deposits obtained in both cases differs very significantly.

In the absence of an electrical device, the deposit obtained after fouling with a solution of WPC has a compact, smooth, very little aerated structure with pores of small diameter (FIG 4a). The deposit obtained with the use of the device has a more ventilated structure with pores of larger diameter (FIG 4b). Thus, the more airy and loose deposit would be more easily removed from the exchange surfaces by the cleaning solutions.

5. EXAMPLE 4 Residual protein fouling deposit mass after cleaning the installation

at. Protocol

After rinsing with water at the end of the test, the plates of the exchanger (3) are dried and weighed as previously described, they are then reassembled for cleaning. At the end of this cleaning, the plates are again disassembled and weighed to determine the residual deposit mass. In our case, in the case of an essentially proteinaceous deposit, the installation is first cleaned with a 2% sodium hydroxide solution at a temperature of 80 ^° C., and secondly after rinsing with water, with a solution of nitric acid at 1.5% at 80 ^° C .; This acidic solution makes it possible to eliminate the minerals present in the deposit. The cleaning is completed by rinsing with water at room temperature. b. Results

The structure of the fouling deposit has a significant impact on the cleaning of the installation. Indeed, the residual deposit mass after the cleaning cycle is greatly reduced from 13.3 g to 1.9 g (-86%) and from 25.6 g to 2.4 g (-91%) respectively. for the WPC solution and for raw milk (Fig. 5). The residual mass obtained with a device (1, 9 or 2.4 g) corresponds to localized deposition at the contact points of the plates, a problem frequently encountered and known. The residual mass obtained without a device (13.3 or 25.6 g) corresponds to a uniformly distributed deposit on the plates, and not only located at the points of contact (see Table 1).

The modification of the structure of the deposit resulting from the process according to the invention facilitates cleaning by a priori favoring the diffusion of the hydroxyl ions by increasing the porosity.

6. Summary table The table below summarizes the results of the fouling experiments. Table 1: Summary of results of fouling experiments

Claims

claims

A method for reducing protein fouling of a milk-derived protein fluid processing plant, said method comprising a step of subjecting said protein fluid to a low-frequency variable electromagnetic field on at least one section. a fluid flow line of said processing plant and wherein said variable electromagnetic field has a frequency of from about 0.5 kHz to about 100 kHz and a low intensity magnetic component.

2. Method according to claim 1 characterized in that the variable electromagnetic field is an electromagnetic field with discontinuous variations

3. Method according to any one of claims 1 or 2 characterized in that the variable electromagnetic field is generated by an electrical apparatus comprising (i) a variable current generating device and (ii) one or more inductors arranged around or from and other of said fluid flow line section of the treatment plant.

4. Method according to claim 3 characterized in that the electrical apparatus comprises one or more electric coils wound around said fluid flow line section of the treatment plant as inductors.

5. Method according to claim 4 characterized in that said electrical apparatus comprises at least one electrical coil connected by its two ends to said variable current generator device.

6. Method according to claim 4 characterized in that said electrical apparatus comprises at least two electrical coils each connected at one end to the variable current generator device.

7. Method according to claim 6 characterized in that said electrical apparatus comprises

(i) a variable voltage generator delivering a voltage selected from the group consisting of the square-shaped voltages and the pulse voltages, possibly modulated in frequency, and (ii) at least two electrical coils each connected by only one of their ends. to the variable voltage generator.

8. Method according to any one of claims 4 to 7 characterized in that the electrical apparatus is disposed on a section of fluid flow conduit located at the entrance of the treatment plant.

9. Method according to any one of claims 1 to 8 characterized in that said treatment plant comprises at least one heating heat exchanger.

10. Method according to any one of claims 1 to 9 characterized in that said protein fluid derived from milk is selected from the group consisting of reconstituted solutions of milk proteins, whey, milk and food preparations derived from milk

The method of any of claims 1 to 10, said method comprising the further step of removing protein fouling from the treatment facility.

12. Use of an electrical device generating a variable low frequency magnetic field to reduce protein fouling of a plant for processing a protein fluid derived from milk.

13. Apparatus for treating a protein fluid derived from milk comprising (i) means for feeding or injecting the protein fluid

(ii) a heated heat exchanger

(iii) an outlet means for the treated or transformed protein fluid

(iv) a plurality of fluid flow conduits and,

(V) an electrical device generating a variable electromagnetic field with a frequency ranging from 0.5 kHz to 100 kHz, said device being placed on at least one section of a fluid circulation duct of the installation.