FR2907462A1 - Reducing concentration of undesirable compound present in contaminated fermented drink e.g. wines and beers, comprises contacting drink in constant flow with adsorbent medium constituted of nanoporous granules with monodisperse granulometry - Google Patents

Abstract

The process for reducing a concentration of an undesirable compound present in a contaminated fermented drink (11) such as wines, beers and liqueurs, comprises contacting the drink in constant flow with an adsorbent medium (1) constituted of nanoporous granules with monodisperse granulometry for a duration delta t, determining the concentration of the compound of the treated drink, and comparing the obtained concentration with a threshold value of concentration of a predetermined compound corresponding to non-contaminated drink. The process for reducing a concentration of an undesirable compound present in a contaminated fermented drink (11) such as wines, beers and liqueurs, comprises contacting the drink in constant flow with an adsorbent medium (1) constituted of nanoporous granules with monodisperse granulometry for a duration delta t, determining the concentration of the compound of the treated drink, and comparing the obtained concentration with a threshold value of concentration of a predetermined compound corresponding to non-contaminated drink. A diameter of the pores is 0.5-10 nm to selectively trap the undesirable compound having a corresponding size. The determined concentration is higher than the threshold value. The adsorbent medium is reticulated non-functional polystyrene, which has an internal surface higher than 1500 m2>/g. A reticulation rate of the polystyrene is higher than 50%. An external surface of the granule has a physico-chemical affinity to attract the undesirable compound present on an internal wall of the pores. The medium is regenerated after the determined concentration is higher than the threshold value.

Description

METHOD FOR REDUCING CONCENTRATION OF ADVERSE COMPOUNDS PRESENT

  The present invention relates to a method for reducing the concentration of undesirable compounds present in a contaminated fermented beverage, such as wines, beers or liqueurs. The high-dose presence of certain undesirable compounds generally leads to an alteration of the organoleptic qualities of the beverage and some of these high-dose compounds in the drink may sometimes entail a risk of toxicity to the consumer. In some wines, especially in a red wine, one can sometimes detect an olfactory note described as stable smell, horse sweat and animal leather. The perception of this note, sometimes judged positively low, becomes a defect beyond a certain level that is variable depending on the type of wine. These organoleptic problems are caused by the yeasts of the Brettanomyces type which develop during the aging of beverages or bottled, and produce, by degradation of phenolic acids, volatile phenols, such as 4-ethylphenol and 4-ethylguaiacol. These compounds once present in the wine are very stable over time and their thresholds of perception are of the order of 450 μg / l for 4-ethylphenol and 50 μg / l for 4-ethylgaïacol.

2907462 2 Among the sensory deviations of the wines, we also find moldy moldy defects which are mainly linked to the presence of geosmin, a compound of microbial origin. Its appearance usually results from a defective state of the harvest. The threshold of perception of geosmin is of the order of 60 ng / I. Another sensory defect frequently encountered in wines is moldy / corky. The latter is in particular due to the presence in wine of organochlorine compounds of the chloroanisole family, in particular 2,4,6-trichloroanisole and 2,3,4,6-tetrachloroanisole. Chloroanisoles are derived from chlorophenol transformation by mold. The chloroanisoles present in the wine are transmitted by cork corks but also by the contaminated atmosphere. The detection threshold of chloroanisoles is extremely low, of the order of a few ng / l. Another problem encountered in wines is related to the presence of toxic substances such as ochratoxin A (OTA) which is a naturally occurring mycotoxin produced by secondary metabolites of Aspergillus and Pencillium type molds. These molds can grow on the grapes after veraison, and penetrate the skin by grape wounds. These substances have adverse effects on health, for this reason a maximum limit level has been set in wines at 2pg / I. Preventive and curative treatments are known to reduce the concentration of these undesirable compounds described above. In order to limit contamination, preventive measures are applied by monitoring the health status of the harvest and the application of good hygiene practices. It is thus known in the case of treatment of problems caused by the yeast Brettanomyces to use for example flash pasteurization or the action of Dimethyl Dicarbonate (DMDC). As a decontamination treatment, the active carbon treatment is mainly known which retains by wall effect molecules and membrane retention treatments.

It has been observed, however, that all these treatments do not offer an optimal treatment on the one hand in terms of efficiency and, secondly, in terms of selectivity of the undesirable compounds. Indeed, activated carbon (FIGS. 1.A, 1.B and 1.C) is an extremely porous adsorbent with a very high adsorbent capacity which can retain, by wall effect, minute molecules. However, the image of FIG. 1.A shows that it is a medium 16 having a heterodispersed particle size and the pores present on the surface have very variable sizes (FIG.

1B), ranging in size from microscopic to macroscopic, thus offering little size selectivity. Therefore, the adsorption by such a medium is very selective because molecules of different sizes can be adsorbed by the charcoal, for example anthocyanin-type molecules responsible for the color of the wines and molecules that contribute to the structuring of the wine such as tannins can be adsorbed by coal. The sectional view of activated carbon granule in Figure 1.0 shows that large molecules 14 can migrate large pores inward and become trapped. A beverage treated with such a low-selectivity medium is generally taste-depleting, and when used at a high dose may sometimes result in denaturation of the treated beverage.

It is therefore imperative for the wine and winemaking industries to have a process that is both efficient and selective, which makes it possible to reduce the presence of the undesirable compounds present in the beverage only to an organoleptically tolerated level. and from a toxic point of view, while preserving the quality of the wine.

The process of the invention proposes the use of an adsorbent medium which is characterized by a specific porosity adapted so as to trap only compounds of a given size in the pores. In addition, this selection by size is conjugated to a physico-chemical affinity between the undesirable compounds and the surface of the medium.

The object of the present invention is therefore to provide a process for reducing the concentration of undesirable compounds in a fermented beverage, simple in design and in its economical mode of operation, allowing the selective removal of only those compounds which are 2907462 4 responsible for the problems of bad tastes, bad smells, and toxicity in order to improve the quality of drinks while preserving the other molecules involved in the structuring of drinks. The present process is particularly suitable for treating wines.

For this purpose, the invention relates to a method for reducing the concentration of at least one undesirable compound present in a contaminated fermented beverage. According to the invention, the process comprises the following steps: (a) said beverage is brought into contact with an adsorbent medium consisting of porous granules and having a monodisperse granulometry, the pore diameter being between 0.5 nm and 10 nm for selectively trap said at least one undesirable compound having a corresponding size, (b) determining the concentration of said at least one compound of the treated beverage at the end of step (a) C ,, and comparing said obtained concentration with a threshold value Cs of the concentration of said at least one predetermined compound corresponding to the uncontaminated state of the beverage, (c) repeating step (a) as long as C, determined in step (b) is greater than at said threshold value Cs. Said at least one undesirable compound is a compound of the family of volatile phenols, the family of geosmin, the family of chloroanisoles or ochratoxin (OTA). The porous adsorbent medium is a non-functional crosslinked polystyrene. Advantageously, in addition to step (a) of the method, the outer surface of said granules has a physicochemical affinity adapted to attract said at least one undesirable compound and said at least one compound is attached to the inner wall of said pores by physico-chemical affinity. In one embodiment of the invention, the contact between said beverage with said medium is performed by passing said beverage through said medium at a constant rate. In another embodiment of the invention, the contact between said beverage and said medium is effected by suspending the granules in the beverage for a period of time. The invention also relates to a wine treated by such a process described herein. -above.

The invention will be described in more detail with reference to the accompanying drawings in which: FIGS. 1A and 1B respectively show an image of the activated carbon and an electron microscopy image showing the state of porosity of the surface of a granule of activated carbon, Figure 1.0 shows a sectional view of a granule of activated carbon; FIGS. 2A and 2B respectively represent an image of a granular adsorbent medium of nanoporous polystyrene used in the process of the invention and an electron microscopy image showing the state of surface porosity of a granule of polystyrene nanoporous, Figure 2.0 shows a sectional view of such a granule; FIG. 3 represents a non-functional crosslinked polystyrene; FIG. 4 represents results obtained from three reduction tests by suspending respectively nanoporous granules of polystyrene, microporous polystyrene granules and active carbon in an artificially contaminated red wine; FIG. 5 and FIG. 6 represent the results obtained from the tests carried out on a red wine according to a particular embodiment of the invention, respectively at a small scale (volume of wine treated = 20 liters) and at 20 industrial scale (volume of treated wine = 80 HL); - Figure 7 is a schematic representation of an example of an installation implementing the method of the invention. According to the invention, the method for reducing the concentration of undesirable compounds 4 present in a contaminated beverage comprises a first step of contacting the beverage with an adsorbent medium 1 consisting of nanoporous granules 2 and monodisperse granulometry. The pore diameter 3 is between 0.5 nm and 10 nm to allow only undesirable compounds 4 having a corresponding size to enter. In the context of the invention, the target undesirable compounds which contaminate the beverage are compounds of the family of volatile phenols, the family of geosmin, the family of chloroanisoles or ochratoxin 2907462 6 (OTA). The process makes it possible to reduce in particular the following compounds: 4-ethylphenol (4EP), 4-ethylguaiacol (4EG), 4-vinylphenol (4VP), 4-vinylguaiacol (4VG), 2,4,6-trichloroanisole (TCA ), 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), geosmin and ochratoxin.

5 Contaminated beverage is a beverage with poor organoleptic quality and / or a risk of toxicity to consumers. The threshold value of the concentration of each undesirable compound Cs was predetermined in the beverage. When the undesired compound is present in the beverage at a concentration above this threshold value, it is determined that the beverage is contaminated. This threshold value Cs generally depends on the type of beverage to be treated and the nature of the undesirable compound. A drink with a risk of toxicity means a beverage with a concentration of toxic substances that is above the prescribed regulatory limit.

In order to assess the effective reduction of the concentration of these undesirable compounds, at the end of the first step of the process, the concentration of the compounds remaining in the Cl drink is thus determined and compared with the threshold value Cs. The dosage of these compounds can be carried out by HPLC or by chemical method.

This quantitative evaluation is supplemented preferably by a qualitative assessment, an appreciation by the organoleptic characters of the drink by making taste the drink thus treated by a group of testers. When the concentration of the undesirable compounds is above the threshold value, the first step is repeated by contacting the beverage with the adsorbent medium again. The adsorbent medium used for carrying out the process is a non-functional crosslinked polystyrene formed from a polymerization of styrene and a crosslinking with divinylbenzene. Figure 3 shows the chemical structure of such a cross-linked polystyrene, preferably used in the form of granules. By non-functional polystyrene is meant a polystyrene which does not have a functional group intended for a chemical bond or an ionic bond. It is usually synthetic and inert.

By using such a polystyrene as a nanoporous adsorbent medium, the method makes it possible to conjugate two selection parameters in order to trap only the undesirable compounds mentioned above: the physico-chemical affinity between the compounds with the outer surface of the polystyrene granules and the inner wall of the pores and the pore size between 0.5 nm and 10 nm which allow penetration only those compounds having a corresponding size. When the beverage is brought into contact with the naoporous polystyrene, in addition to the selection of compounds by their size, the undesirable compounds 4 are therefore first attracted by physico-chemical affinity by the surface of the granules. In a second step, a selection by their size is carried out, only compounds whose size corresponds to that of the pores can migrate to the inside of the pores. These two selection phases make it possible to avoid, for example, trapping molecules of structure of the wines, and to avoid a taste impoverishment.

In order to obtain an optimum reduction effect, the polystyrene used in the process is preferably a monodisperse granular size polystyrene (FIG. 2.A), a granule diameter of between 1.45 mm and 0.5 mm. The granules 2 are arranged in a network. It preferably comprises a degree of crosslinking greater than 50% and an internal surface greater than 1500 m 2 / g.

Polystyrene is also characterized by an apparent density of 750 g / l and a water content of between 38 and 45%. FIG. 2.B shows an image obtained by electron microscopy of the pores 3 present on the surface of the granules 2. They are arranged in a network and the size varies very little from one pore to the other, so that the difference between both extreme sizes are narrow enough to be able to selectively trap compounds while excluding large molecules. Figure 2.0 schematically shows a sectional view of a polystyrene granule, the size of the pores is adapted such that it allows only enter the undesirable compounds 4 of corresponding size.

After entering the pores, the compounds are trapped within the pores of the adsorbent medium and are then attached to the inner wall of the pores by physico-chemical affinity.

According to one embodiment of the invention, the beverage is contacted with the medium by suspending the polystyrene granules in the beverage for a time At. FIG. 4 illustrates an application of this embodiment of the invention. process for an artificially contaminated red wine. Polystyrene is suspended in the wine at a dose of 100mg of polystyrene in 100ml of wine. Analyzes of the following compounds: 4-ethylphenol (4EP), 4-ethylgaïacol (4EG), 4-vinylphenol (4VP) and 4-vinylgaïacol (4VG) remaining in the red wine are made after 24 hours of contact.

The characteristics of the polystyrene are the following: - granule diameter: 1.45 mm - 0.5 mm - a degree of crosslinking greater than 50% an internal surface greater than 1500 m 2 / g - pore diameter: 0.5 nm The results obtained are compared with the other two examples of reduction using, as adsorbent medium, a microporous polystyrene having a pore diameter of between 50 and 100 nm and activated carbon. Both tests are performed under the same conditions as the first test. The results show that nanoporous polystyrene and microporous polystyrene are more effective in adsorption than coal. For example, the adsorption rate for 4-ethylphenol (4EP) is 42% for nanoporous polystyrene and 33 for microporous polystyrene and only 25% for activated carbon. The results also show that polystyrene with a pore diameter of 0.5 nm to 10 nm is more efficient than microporous polystyrene with a pore diameter of 50 nm to 100 nm. The comparison between the adsorption efficiency of the two polystyrenes shows that it is necessary to use a nanoporous polystyrene, preferably between 0.5 nm and 10 nm.

In parallel, spectrometer analyzes on the indices to be preserved DO280 and IC 'are also carried out to verify the selectivity of the polystyrene, OD280 corresponds to the index of total polyphenols and IC' the color intensity of the wine.

The results show that the nanoporous polystyrene is more selective than the other two adsorbent media, there is less loss of compounds responsible for the structure of the wine and its color. The least selective is activated carbon, there is almost a loss of 50% for example for D0280.

According to another embodiment of the invention, to bring the beverage into contact with the medium, the beverage is passed through the adsorbent medium at a constant rate. By regulating the flow rate, the contact time Δt between the drink and the medium is varied. FIG. 5 shows the results obtained from a test carried out according to this other embodiment. 100m1 of nanoporous adsorptive polystyrene are supported by a glass column with a diameter of 45 mm and a length of 260 mm. The adsorbent is washed beforehand with 200 ml of demineralized water in order to eliminate any soluble residues. The column is fed by a peristaltic pump to work at constant flow 200m1 / min. The test is carried out at room temperature, and the characteristics of the polystyrene nanoporous are those of the polystyrene used in the test of Figure 4. The test relates to a treatment of 20 liters of red wine, naturally contaminated. A sample of the wine is taken for the first liter of wine after passing through the polystyrene, then the 5th, 10th, 15th and 20th liter to check the evolution of the effectiveness of the polystyrene during the test. Table 1 relates to the effectiveness of polystyrene in removing the following compounds: 4-ethylphenol (4EP), 4-ethylguaiacol (4EG), 4-vinylphenol (4VP), 4-vinylguaiacol (4VG). Table 2 relates to the effectiveness of polystyrene in removing the following compounds: 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2 , 4,6-trichlorophenol (TOP), 2,3,4,6-tetrachlorophenol (TeCP), and pentachlorophenol (PCP). Tables 3 and 4 respectively relate to the effectiveness of polystyrene in removing geosmin and ochratoxin.

The results of Tables 2, 3 and 4 show that the polystyrene remains effective throughout the test for the compounds listed in Tables 2, 3 and 4.

The overall results show that the nanoporous polystyrene is effective in reducing the concentration of the compounds mentioned above. However, the adsorption rate values in Table 1 show that the capacity of the polystyrene to adsorb 4-ethylphenol (4EP) decreases during the test, between the first liter treated and the 20th liter treated. For example, for 4-ethylphenol (4EP), it went from 97% elimination for the first liter to only 50% elimination for the 20th liter, likewise for 4-ethylguaiacol (4EG). The results indicate that it is preferable to add an additional step at the end of the reduction process in which the polystyrene is regenerated to be used again. However it can also be simply replaced by a new polystyrene cartridge. FIG. 6 illustrates the influence of the flow rate on the efficiency of the process of the invention in the context of a test on an industrial scale for two tanks of red wine by passing them through the polystyrene with different flow rates. The total volume of each vat of treated wine is 80 HL. The conditions for carrying out the process are as follows: a column of 100 cm and a diameter of 12 cm containing approximately 8 liters of nanoporous polystyrene; the characteristics of the nanoporous polystyrene are the same as those of the polystyrene of the tests described on the Figure 4 and Figure 5, and it is cleaned beforehand - test temperature T = 15-20 C Table 1 shows the reduction results with a flow rate at 20 HL / hour and Table 2 the reduction results with a flow rate at 10 HL / hour. To test the effectiveness of the polystyrene during the test, samples were taken on the 20th, 42nd and 80th hectoliters during the test. The results show that there is almost no loss of polystyrene adsorption efficiency after treating 80 HL for both flow rates. Comparing the reduction rates for 4-ethylphenol (4EP) and 4-ethylguaiacol (4EG) in Table 1 with those in Table 2, the results show that there is an improvement in adsorption when the flow rate has gone from 20 HL / hour to 10HI / hour. In fact by reducing the flow rate, the contact time between the polystyrene and the wine was increased, in other words the volume of drink to be treated per hour was reduced relative to the volume of resin used. FIG. 7 represents an example of installation 13 implementing the method of the invention. It comprises a reduction unit 5 comprising an upper compartment 6 and a lower compartment 7 separated by a granular adsorbent medium 1 consisting of non-functional nanoporous polystyrene granules, an inlet connecting the upper compartment to a first tank 8 containing contaminated beverage 11. The compartment 6 is fed via a pump so as to be able to work at a constant flow rate, an outlet situated in the lower part of the unit 5 connecting the lower compartment 7 to a second tank 12 for recovering the beverage thus treated. Advantageously, another input of the reduction unit is connected to regeneration means comprising a regenerator reservoir 9. The regenerator 10 can be manually sent by an operator to the adsorption unit 5 at the end of the reduction process. to regenerate polystyrene when reused. A wine sample is taken from the reservoir 12 to determine if the concentration of undesirable compounds is below a set threshold value Cs, this step is generally completed by a qualitative assessment by performing taste tests. This step determines whether it is necessary to iron the beverage to be decontaminated in the reduction unit 5. If the concentration of the undesirable compounds is lower than the threshold concentration Cs, the beverage is sent directly to a storage tank 14. It should be noted that the method of the invention can be used to treat any fermented beverage (wine, brandy, beer, etc.) contaminated by the presence of a high dose of compounds such as compounds of the family of volatile phenols, the family of geosmin, the family of chloroanisoles or ochratoxin (OTA). 30

Claims (10)

  A method for reducing the concentration of at least one undesirable compound (4) present in a contaminated fermented beverage (11), characterized in that said process comprises the following steps: (a) said beverage is brought into contact with a medium adsorbent (1) consisting of nanoporous granules (2) and monodisperse granulometry, the diameter of the pores (3) being between 0.5 nm and 10 nm to selectively trap said at least one undesirable compound having a corresponding size, (b) the concentration of said at least one compound of the treated beverage is determined at the end of step (a) C 1 and said obtained concentration is compared with a threshold value C s of the concentration of said at least one predetermined compound corresponding to the uncontaminated state of the beverage, (c) step (a) is repeated as long as C, determined in step (b), is greater than said threshold value Cs.   2. Process according to claim 1, characterized in that the said at least one undesirable compound (4) is a compound of the family of volatile phenols, of the family of geosmin, of the family of chloroanisoles or of ochratoxin (OTA) .   3. Method according to claims 1 and 2, characterized in that said adsorbent medium (1) is a non-functional crosslinked polystyrene.   4. Method according to claim 3, characterized in that said polystyrene has an internal surface greater than 1500 m 2 / g.   5. Method according to claims 3 and 4, characterized in that said polystyrene has a degree of crosslinking greater than 50%.   6. Method according to claims 1 to 5, characterized in that in addition to step (a), the outer surface of said granules has a physicochemical affinity adapted to attract said at least one unwanted compound (4) and said at least one undesirable compound (4) is attached to the inner wall of said pores (3) by physicochemical affinity.   7. A method according to claims 1 to 6, characterized in that the contact between said beverage (11) with said medium (1) is carried out by passing said beverage through said medium at a constant rate. 2907462 13   8. Method according to claims 1 to 6, characterized in that the contact between said drink (11) with said medium (1) is carried out by suspending the granules (2) in the drink for a time At.   9. A method according to any one of the preceding claims characterized in that said method comprises an additional step wherein said medium is regenerated after step (c).   Fermented beverage (11) treated by said process according to one of the preceding claims, characterized in that said beverage is a wine.