FR3052640A1 - PROCESS FOR TREATING PLANT PRODUCTS WITH ALCOHOL VAPORS - Google Patents

Abstract

The process comprises treating fruits and vegetables by applying a C3-C9 alcohol in the form of steam.

Description

Process for treating plant products with aicooi vapors

The present invention relates generally to the processing of fruits and vegetables, including alcohol vapor. Said treatment aims in particular to prolong their conservation and has in particular a phytoprotective action, biocide or anti-germinative.

It is known to treat fruit and vegetables with alcohol and possibly another active ingredient, by thermal fogging. Thus, patent application US 2014/0200137 describes an application by thermal fogging, spray or aerosol. The treatment composition is therefore present in the form of fine droplets of liquid, the average size of which is approximately 1-1 μm. The liquid is therefore applied instantaneously or extremely fast, so as to produce a sufficient concentration to destroy the already existing potato sprouts. Even though partial evaporation of the active ingredient may exist, this does not make it possible to obtain a perfect distribution of the product over the entire surface. The fog obtained also does not make it possible to treat the stored products, in particular in paiox or bags, insofar as the mist formed can not transit through the containers. In addition, the droplets formed or resulting from the condensation of the vapors fall back on the foodstuffs at concentrations which may be phytotoxic.

In this context, there is therefore a need for a process for applying the active ingredient and in particular the alcohols in vapor form, without risk of condensation, and / or phytotoxicity while allowing a homogeneous concentration of vapor in the whole of storage space and controlling the amount of steam introduced. To this end, the invention relates, according to a first object, to a method for treating plant products comprising evaporation of a liquid composition comprising a C3-C9 alcohol, and characterized in that said method comprises the application alcohol vapor at a concentration lower than the saturation concentration of the alcohol in the atmosphere on said plant products.

The method is particularly suitable for the anti-germinal treatment of bulbs and tubers, especially potatoes.

The evaporation method according to the invention makes it possible to produce high concentrations of alcohol in gaseous form up to concentrations slightly lower than the saturation concentration of the alcohol in the atmosphere, and in particular for long periods of time. for large volumes.

The risk of condensation of alcohol on stored foods, and thus the phytotoxicity of alcohol, are in fact avoided, because as the concentration of saturation in the atmosphere approaches, evaporation will no longer occur. and there is no risk of oversaturation.

Thus, the hazards of the thermal fogging of a composition in liquid form are avoided, producing directly and in a controlled manner alcohol vapors. The application in vapor form is advantageous in that it allows a simple and controlled application, while leaving minimum amounts of residues. The application in the form of steam also makes it possible to reach present fruits and vegetables stored in large volumes, in bulk, bags or pallox.

The vapor produced consists of molecules having a diameter of about 10 Angstrom ($), ie diameters much smaller than the size of the droplets produced by thermal fogging (about 1pm). The vapor thus formed is thus composed of particles one billionth of a heavier times and allows a longer exposure time.

The vapor cloud created has a homogeneous concentration in all parts of the storage space. In addition, the method according to the invention makes it possible to optimize the amount of composition, insofar as the entire composition is evaporated to the desired concentration. The method according to the invention also allows a controlled application over time as a function of the quantity of composition desired. The method according to the invention makes it possible to avoid the single application, usually carried out in the case of a liquid applied at the beginning of conservation, or very spaced (in the case of nebulization). It is thus possible to immediately obtain a curative and preventive effect.

Typically, the process comprises the step of evaporating the composition at room temperature, below 50 ° C. According to one embodiment, this is achieved by a flow of gas at room temperature. The method according to the invention therefore allows evaporation of the liquid without the need for heating means. The method according to the invention also does not require high-pressure injection, which generally involve high installation costs, and which do not make it possible to avoid the subsequent condensation of the evaporated liquid. The idea underlying the invention is therefore to provide a treatment that is spread over a long period, as opposed to known treatments in which a large amount of products is injected punctually over a very short period. This makes it possible to inject the product in small quantities, progressively, so that the concentration of products inside the closed chamber remains constantly at a moderate level.

In addition, the system self-regulates, the product being vaporized at ambient temperature, lower than 50 ° C, it evaporates until it reaches the saturation of the atmosphere without risk of oversaturation (which is the case when heating ). This prevents the liquid recondense after injection. The condensation of the liquid leads to the formation of drops that can fall back on the stored food products, and be phytotoxic to them. In contrast, the evaporation according to the process of the invention allows excellent diffusion and excellent penetration into the mass of plant products stored inside the closed chamber, due to the absence of condensation in the form of droplets . This leads to product concentrations on plant products or on the inner walls of the closed enclosure relatively constant and moderate.

In addition, the vapor molecules uniformly fill the atmosphere and diffuse more easily than the droplets of liquids, especially in plant products stored in bulk or in large volume containers such as paliox or Big-Bags.

"Vegetable products" means all plant foods and in particular fruits and / or vegetables.

According to one embodiment, the alcohol is chosen from isopropanol, butanol, amyl alcohol, hexanol, heptanol, 2-ethylhexanol, 2-octanol, 1-octanol and isooctanol. , nonanol, and their C3-C9 isomers and mono-unsaturated C3-C9 alcohol equivalents.

According to one embodiment, the alcohol is chosen from C 6 -C 8 alcohols.

Said composition may further comprise one or more solvents and / or one or more excipients. Alternatively, the liquid composition comprises an aqueous or organic solvent, in which the alcohol is dissolved. The aqueous solvent is, for example, water. The organic solvent is for example a solvent of the type described in FR 2791910 or glycols, diglycols and their relative esters. The excipients are, for example, substances capable of transporting the active substance (s) or capable of giving a dilution effect.

According to one embodiment, said composition may also comprise another active principle with phytoprotective, biocidal and / or anti-germinative activity, such as in particular an essential oil according to the mixture or one of the constituents of these oils and / or their mixtures. Thus, mention may be made of mint oil, clove oil, rose oil, thyme oil, oregano oil, cinnamon oil and eucalyptus oil. Alternatively, or additionally, said composition comprises one of the constituents of these oils selected from the group consisting of L-carvone, eugenol, geraniol, thymol, carvacrol, cinnamaldehyde, eucalyptol . Said active ingredient may also be a volatile synthetic product, such as dimethyl-naphthalene, 3-decene-2-one or hexanal. Alternatively, said composition may also comprise pyrethrum or synthetic pyrethrins, and / or synthetic synthetic biocides such as glutaraldehyde.

Typically, the composition comprises only the alcohol without a solvent or excipient.

The method according to the invention allows the application of alcohol at daily doses of between 1 and 100 g / metric tons. According to one embodiment, the alcohol is applied at a frequency of between 2 and 30 days per month.

According to the process according to the invention, the alcohol is applied in the form of steam at a concentration lower than the saturation concentration of the alcohol in the atmosphere. The operating conditions are such that there is no condensation of the alcohol and / or formation of liquid droplets and / or deposition of alcohol in liquid form on the treated plant products. In other words, the evaporated alcohol is exclusively present in the form of steam. Generally, the concentration of the alcohol is less than 30 g / m 2, typically between 0.2 and 4 g / m 2. This concentration may vary depending on the nature of the alcohol and the conditions of application.

The process according to the invention is advantageously carried out by evaporation of the composition in a closed chamber in which fruits and vegetables are stored.

The term "closed enclosure" here refers to an enclosure having a relatively high level of tightness, so that the internal atmosphere of the enclosure does not communicate with or communicate with the atmosphere outside the enclosure. As explained below, it is important that the product or products injected into the enclosure do not escape into the external atmosphere, or escape at a reduced flow rate, low enough not to penalize the consumption of liquid and of products. The closed enclosure is for example a room, a silo, a greenhouse or any room for storing plant products such as fruits or vegetables. The treatment is applied while the plant products are stored in the closed enclosure, or on the contrary while the closed enclosure is empty. The closed chamber is generally maintained at the temperature corresponding to the storage conditions of the fruits and vegetables.

Thus, the temperature is generally below 15 ° C, typically between 7 and 9 ° C.

In any case, the liquid during the injection phase is vaporized at a temperature of less than 50 ° C., preferably inferred at 20 ° C., especially between -2 ° C. and + 12 ° C., and especially between 0 and 0 ° C. For example, the liquid is evaporated at room temperature. Other features and advantages of the invention will emerge from the detailed description given below, by way of indication and in no way limiting, with reference to the appended figures, among which: FIGS. 1 to 5 are diagrams of time illustrating various embodiments of the invention; FIG. 6 is a view similar to that of FIG. 6, in which the treatment device of the invention is mounted in a plant product storage chamber; FIGS. 7 and 8 are graphs making it possible to determine the rate of elimination of a product inside a closed enclosure; FIG. 9 is a diagrammatic representation of a treatment device intended for the implementation of FIG. process of the invention; and FIG. 10 is a schematic representation of a vaporizer adapted to evaporate high liquid flow rates.

According to one embodiment, the method comprises the following steps: absorption of the liquid by an absorption member (16); producing a flow of gas, the flow of gas being directed towards the absorption member (16); and evaporation of the liquid at a temperature below 50 ° C.

According to one embodiment, the method is such that the liquid is evaporated and is injected inside the enclosure closed by a vaporizer

According to a first variant, the vaporizer 18 typically comprises, as illustrated in FIG. 9, a reserve 22 containing the liquid; a member 24 for absorbing the liquid; a member 26 for producing a flow of gas, the flow of gas being directed towards the absorption member 24. The absorption member 24 comprises a plurality of absorbent strips 28, suitable for retaining the liquid. The absorbent strips are for example arranged vertically, or are inclined with respect to the vertical with an inclination allowing the liquid to flow by gravity from the upper end of the band towards the lower end. The strips are for example arranged in V, the tip of the V pointing upwards. They can be arranged in W or accordion.

The absorbent strips 28 are typically made of microfibers, vegetable or synthetic, for example formed by 80% of polyester and 20% of polyamide. The member 26 for producing a gas flow is for example a fan, oriented so as to create a stream of air towards the absorbent strips 28.

The stream of air charged with vaporized liquid is channeled through a conduit 29 opening into the internal atmosphere of the closed enclosure. As a variant, the liquid absorption member 24 and the gas flow production member 26 are placed directly inside the closed chamber, the member 26 setting in motion the internal atmosphere of the closed enclosure (Figure 7).

Advantageously, the vaporizer 18 comprises a member 30 for injecting the liquid into the absorption member 24 from the reserve 22. This injection member 30 comprises a metering member 32, for example a dosing pump. This metering member 32 controls the flow of liquid injected into the absorbent strips 28. The liquid is injected at the upper end of each strip, and flows by gravity to the lower end of each strip.

Preferably, the vaporizer 18 is configured so that all the injected liquid is evaporated before reaching the lower end of each strip 28, so as to perfectly control the flow of evaporated liquid. This result is obtained by appropriately selecting, depending on the nature of the liquid, the area of the strips, the flow of liquid injected into each band, and the gas flow.

Such a vaporizer is sold by XEDA INTERNATIONAL under the name XEDAVAP®.

The absorbent strips can be formed from a single sheet folded along parallel horizontal lines fan or accordion. The predetermined flow, at which the liquid is injected into the absorbent strips 28, is automatically controlled at a set point. The predetermined flow is controlled at the setpoint by a computer 20, or a computer 20, or any other similar device. The computer 20 acts on the injection member 30 to control the predetermined flow. The predetermined flow rate, at which the liquid is injected, is chosen such that the liquid is completely evaporated as it flows by gravity along the absorbent strips 28 towards the second ends and that no drop of liquid falls from In this way, the amount of liquid that is evaporated can be controlled very precisely. Said amount corresponds exactly to the predetermined flow rate injected into the absorbent strips, and controlled by the computer 20. If drops of liquid fall into the absorbent strips, it means that the amount of liquid that is evaporated is lower than the predetermined flow rate injected into the absorbent strips. It is then difficult to assess the quantity of liquid that has actually been evaporated and to control precisely said amount. It should be noted that for the treatment of food products in order to extend their preservation, the quantity of liquid actually evaporated must be precisely controlled to obtain good results. Droplets of liquid falling from the absorbent strips 28 are automatically detected. For this purpose, a drip tray can be arranged under the absorbent strips. The bottom of the drip tray is arranged such that drops falling from the absorbent strips 28 are collected by the drip tray and flow along the sump. The drip tray is equipped with a liquid sensor, arranged to detect if liquid is present in the sump.

The liquid sensor is connected to the computer 20, and indicates to the computer 20 when liquid is present in the sump or not.

If drops of liquid falling from the absorbent strips 28 are detected, the predetermined flow rate is reduced to another predetermined value, at which droplets of liquid do not fall automatically reduces the predetermined flow rate.

Alternatively, an operator may manually reduce the predetermined flow value.

The fact that the absorption member comprises a plurality of absorbent strips makes it possible to obtain a large area of contact between the gas flow and the absorption member, and therefore a large surface area for evaporation of the liquid. In addition, the absorbent strips are advantageously spaced apart from each other so that the absorption member is able to provide a large space for passage of the gas flow. Thus, the process according to the invention makes it possible to evaporate a large quantity of liquid.

According to a first embodiment, the method according to the invention comprises the injection of the composition into the absorption member from the reserve. By "injection" is meant here the fact of introducing, by a voluntary, positive action, a quantity of liquid into the absorption member.

Preferably, the injection is carried out by pumping, by means of a dosing pump for example. Such a dosing member makes it possible to precisely control the quantity of liquid injected. Alternatively, the liquid is injected by gravity, by venturi effect, or by any other suitable metering device.

Typically, the metering pump and the production member of the gas flow are controlled by a computer. Alternatively, the metering pump and / or the gas flow generating member are manually controlled.

According to this first embodiment, each band has a first end and a second end and the injection member has a liquid ejection outlet, the ejection outlet being disposed near the first end of each strip. Thus, the liquid is injected into the first end of each strip and flows by gravity along each absorbent strip toward the second end.

According to this first embodiment, the first end of each strip is typically located at the pole of a sphere, each strip extending from the pole along a longitude of said sphere. This configuration makes it possible to optimize the evaporation of the liquid retained in the absorbent strips. Alternatively, the absorption member has a cone shape, patatoïde or any concave shape.

According to this first embodiment, the gas flow production member is directed towards the pole, on the concave side of the sphere. This arrangement of the gas flow producing member with respect to the absorption member allows the flow of gas to be directed so as to optimize the evaporation of the liquid. It allows a better distribution of the air flow with respect to the absorbent strips that retain the liquid to be evaporated. The gas flow generating member is, for example, a fan.

According to a second embodiment, the absorbent strips are arranged parallel to each other and extend along a longitudinal axis, the longitudinal axis being perpendicular to the direction of the gas flow. Alternatively, the longitudinal axis is inclined with respect to the direction of the gas flow.

According to the second embodiment, the device comprises a liquid storage member connected to the reserve, the second end of each strip dipping in the liquid of the storage member so that each strip absorbs the liquid by capillarity.

According to this second embodiment, the device comprises an injection line from the reserve to the liquid storage member. Typically and like the injection member of the first embodiment, the injection line comprises a metering pump.

In a variant of this second embodiment and like the first embodiment, the device comprises a liquid injection member in the absorption member from the reserve.

According to this variant, each band has a first end and a second end and the injection member has an ejection outlet of the liquid, the ejection outlet being disposed near the first end of each strip. Thus, the liquid is injected into the first end of each vertical absorbent strip and flows by gravity along each vertical absorbent strip.

Alternatively, the vaporizer is different. The vaporizer comprises for example a vessel containing the liquid, and a member for producing a flow of gas directed towards the free surface of the liquid.

Alternatively, the vaporizer comprises a tank containing the liquid and a device for bubbling gas through the liquid. The gas after passing through the liquid and being charged with steam is mixed with another gas stream which drives it into the closed enclosure.

The vaporizer can be of any other type, depending on the liquid to be evaporated.

According to one embodiment, the method is such that the liquid is evaporated by contact with an air flow in a packed tower.According to an alternative embodiment illustrated in FIG. 10, the vaporizer 18 comprises a tower 40 comprising a lining 42, a device 44 for injecting the liquid above the lining 42, and a device 46 arranged to create an upward flow of air through the lining 42.

The tower 40 typically comprises a tank 47, placed under the lining 42, and containing the liquid.

The device 44 for injecting the liquid above the lining typically comprises one or more spray bars 48 placed above the lining 42, and a liquid transfer member 50, such as a pump, sucking the liquid into the liner. the tray 47 and pushing it back into the ramp (s) 48.

The device 46 for creating the air flow comprises one or more air inlets 52 opening inside the tower, under the lining 42, and an air circulation member 54, placed above the packing. The member 54 is for example a fan or a blower.

Each inlet 52 communicates fluidly with the internal atmosphere of the closed enclosure 4.

The tower 40 has an outlet 56 for the air charged with evaporated liquid, placed in the upper part, above the packings 42. The outlet 56 is fluidly connected with the internal atmosphere of the closed chamber 4. The body 54 sucks the evaporated liquid-laden air over the packing 42 and discharges it into or towards the outlet 56.

The lining 42 is for example a honeycomb lining.

The vaporizer further comprises a drop separator 58 placed above the spray bars 48.

In an exemplary embodiment, the tower 40 is of vertical axis, and has a substantially constant horizontal section of 700x700mm. The tray 47 has the same horizontal section as the tower, and has a height of between 500 and 700mm.

The vaporizer has for example four inputs 52, each disposed on one side of the tower.

The lining 42 has a height of about 1 meter.

The lining 42 is placed for example 700 mm below the liquid inlet, the drops separator 58 being placed 300 mm above the liquid inlet.

The operation of the vaporizer 18 is as follows.

The liquid 46 to be evaporated is placed in the tank 47. The pump 50 delivers the liquid into the ramp (s) 48, which projects the liquid towards the lining 42. The air circulation member 54 creates a flow of water. rising air. The air enters the tower 40 through the inlets 52, flows upwardly through the lining 42. The liquid flows downwardly through the lining 42, a portion of the liquid being evaporated in contact with the flow of water. air and being driven by the air stream as vapor. The fraction of the liquid that is not evaporated falls back into the tank 47 and is recycled. The air charged with evaporated liquid passes through the drop separator 58 and is discharged by the member 54 to the outlet 56.

The vaporizer 18 is typically placed inside the closed chamber 4. It sucks through the inlet (s) 52 directly to the internal atmosphere, and discharges the vapor-laden air directly into the internal atmosphere, via the outlet 56 .

A method using such a vaporizer, that is to say in which the liquid is evaporated by contact with a flow of air in a packed tower, allows to evaporate a significant amount of liquid, much higher than that it is possible to evaporate in a vaporizer of the XEDAVAP® type.

For example, in the vaporizer illustrated in Figure 9, with absorbent strips having an area of 4m 2, it is possible to evaporate about 1.2 liters per day of mint oil. With the packed tower of Figure 10, it is possible to evaporate an amount much higher than 1.2 liters per day up to 20 liters per day.

This vaporizer has the advantage of being extremely simple, to have a very high evaporation capacity, and to have a relatively modest size.

Due to its high evaporation capacity, it is possible to maintain the internal atmosphere of the closed chamber at a product concentration close to saturation. This allows the product to best perform its action.

More particularly, the process can be carried out by means of the following device provided for the implementation of the method described above.

The treatment device 17 comprises: a vaporizer 18 configured to evaporate a liquid containing the or each product at a temperature below 50 ° C., and to inject the evaporated liquid inside a closed chamber; an electronic device 20 for controlling the vaporizer.

The vaporizer is of the type described above.

The electronic device 20 is for example a computer or a computer part. As a variant, the electronic control device 20 is designed as programmable logic components (FPGAs), or as a dedicated integrated circuit (ASIC, Application Specifies Integrated Circuit).

The electronic control device 20 is programmed to implement the method of the invention described above.

Thus, it is programmed to implement a treatment step lasting longer than or equal to 3 days, this treatment step comprising at least one injection phase of a duration greater than or equal to 3 days during which the vaporizer evaporates the liquid and injects the vaporized liquid with a period less than or equal to 2 days.

The method may comprise a step of determining a magnitude representative of the rate of absorption of the or each product by the plant products, and a step of selecting the liquid injection conditions according to the representative representative quantity.

The duration of the treatment step depends on the type of treatment.

The DT treatment time is generally a function of the DS storage time of the plant products inside the closed chamber. The invention is particularly suitable for cases where the plant products are stored for a long time. The DS storage duration is typically between 3 days and 1 year.

The treatment duration DT is typically greater than or equal to 50% of the storage duration, preferably greater than 75%, more preferably greater than 90% of the storage duration DS.

The treatment duration DT is thus typically between 3 days and 1 year.

For phytosanitary applications, the DT treatment time is a function of the storage duration DS of the plant products inside the closed enclosure. The invention is particularly suitable for cases where the plant products are stored for a storage period of between 3 days and 1 year.

In terms of storage time there are two different cases:

Case of short storage period: from 3 days to 1 month, for example wheat stored in silos before bagging, stone fruits (peaches, nectarines ..), oranges stored in maturation chamber before their packaging. In this case the treatment will last at least 3 days.

Case of long storage period: from 3 months to 1 year, with a duration of treatment also between 3 months and 1 year. The electronic device is then programmed so that the processing time is greater than or equal to 50% of the storage duration, preferably greater than 75%, more preferably greater than 90% of the storage time.

Thus, a treatment is carried out which extends practically over the entire storage period, guaranteeing excellent control of the evolution of the plant products.

In all cases, according to a first embodiment, corresponds to FIGS. 1 to 4, the electronic device 20 is programmed so that the treatment step comprises a single injection phase. The duration of the injection phase is substantially equal to the duration of the treatment step. As a variant, the duration of the injection phase is shorter than that of the treatment step, for example because the last injection operation was performed slightly before the end of the treatment step.

According to a second embodiment, the electronic device is programmed so that the treatment step comprises a plurality of successive injection phase, separated from each other by stop phases without injection (FIG. 5).

The duration of each injection phase and of each stop phase is as described above with respect to the treatment process.

Furthermore, according to a first variant embodiment, the electronic device is programmed so that during each injection phase, several evaporation and liquid injection operations are carried out, typically with a regular interval, that is to say say with a regular period between injections. This is shown in Figures 1, 2, 4 and 5. The period between two injections is, as indicated above, less than 2 days, and is for example a day. In other words, for example, a liquid injection operation is performed per day.

According to another alternative embodiment, the electronic device is programmed to evaporate and inject the liquid continuously, that is to say without any interruption during the entire injection phase.

The electronic device 20 is programmed so that, during the or each injection phase, the liquid is evaporated and injected under conditions chosen so as to maintain a concentration of the or each product in the internal atmosphere of the enclosure closed within a predetermined concentration range.

The concentration range is determined using curves such as those shown in Figures 7 and 8, as described above with respect to the method of the invention.

The evaporation and injection conditions typically comprise one or more of the following parameters: number of injection phases; - duration of each injection phase; number of injection operations in each injection phase; - period between two injection operations, - quantity of products injected at each injection operation; possibly the duration of the stopping period between two injection periods; - etc.

In a variant, the electronic device 20 is programmed so that, during the or each injection phase, the liquid is evaporated and injected under conditions chosen so as to maintain the rate of absorption of the plant protection product by the plant products in a predetermined range.

This range is determined for example using curves similar to that of Figures 7 and 8, as described above.

The conditions include the same parameters as those described above.

The vaporizer can be controlled by the electronic device 20 in different ways.

According to a first variant, the vaporizer operates continuously. It is placed in the internal atmosphere of the closed enclosure. It sucks it and rejects the air charged with steam. Once the internal atmosphere is saturated with product, it is no longer possible to increase the vapor concentration, and the evaporation is stopped naturally.

Alternatively, the electronic device 20 is programmed to start and stop the evaporator according to a predetermined time diagram.

According to yet another variant, the electronic device 20 is connected to an analyzer continuously measuring the concentration of the product vapor in the internal atmosphere of the closed enclosure. It starts, stops or modulates the operation of the vaporizer 18 so as to maintain the concentration within a predetermined range.

According to yet another variant embodiment, the processing device comprises a camera arranged so as to observe the plant products stored in the closed enclosure. The camera is connected to a control station located away from the closed enclosure. This checkpoint includes a screen allowing an operator to see the images taken by the camera, and thus to know the status of plant products stored. Furthermore, the control station is configured to control the electronic control device 20, which allows the operator to adapt the control of the vaporizer, typically to change the dose of product applied to plant products per unit of time.

Thus, a treatment is carried out which extends practically over the entire storage period, guaranteeing excellent control of the evolution of the plant products. The treatment step, as visible in FIG. 1, comprises at least one injection phase with a duration PI greater than or equal to 3 days. During the injection phase, the alcohol is evaporated and injected inside a closed chamber. The treatment step comprises, for example, a single injection phase, as illustrated in FIGS. 1 to 4. In a variant, the treatment step comprises a plurality of injection phases separated from one another by phases of injection. stop without liquid injection, as shown in Figure 5.

The duration of the injection phase is at least 3 days, and at most equal to the duration DT of the treatment step.

In the case of a single injection phase (FIGS. 1 to 4), the duration of the injection phase is substantially equal to the duration of the treatment step DT. As a variant, the duration of the injection phase is shorter than that of the treatment step, for example because the last injection operation was performed slightly before the end of the treatment step.

When the treatment step comprises a plurality of successive injection phases (FIG. 5), the duration of each injection phase is typically between 3 days and 15 days, preferably between 3 days and 10 days.

The duration of each stop phase is typically between 15 days and two months. For example, it is chosen so that the cumulative duration of the injection phase and the next stop phase is one month.

As illustrated in FIG. 1, during the injection phase, the liquid is evaporated and injected with a ΔΤ period of less than 2 days. By this is meant that the injection operations I of evaporated liquid are separated by a period ΔΤ of 2 days maximum. Evaporation and injection of the liquid is for example continuous throughout the injection phase, the period being in this case equal to 0 (Figure 3).

As a variant, the evaporation and the injection of the liquid is fractionated, the injection phase then comprising several separate evaporated liquid injection operations (FIGS. 1, 2 4, 5) spaced from each other by the period ΔΤ . The period ΔΤ is the time between the start of two evaporated liquid injection operations. Evaporation and injection are interrupted between two injection operations. These injection operations are symbolized by an I in FIGS. 1, 2, 4 and 5.

The number of injection operations I during the injection phase is at least 2. Typically, one carries out between two injection operations per day and one operation every two days. For example, an injection operation is performed per day.

The duration of each injection operation is at least one hour and at most twenty-four hours. Typically, it is between 1 hour and 15 hours.

Typically, the injection operations are regularly spaced in time.

The concentration of the alcohol in the atmosphere can be measured in particular by a continuous measuring apparatus equipped with a flame ionization detector for example. In addition, if the atmospheric concentration reaches the saturation concentration of the alcohol evaporation is no longer done.

According to one aspect of the invention, during each injection phase PI, the liquid is evaporated and injected under conditions chosen so as to maintain a concentration of the or each product in an internal atmosphere of the closed chamber included in a predetermined concentration range.

The range of concentration depends on the intended application and the product. It is generally determined experimentally, as described below. For example, a total gradient between 50 and 2000 ppm of concentration in the atmosphere is targeted.

The term evaporation and injection conditions here means one or more of the following parameters: duration of the treatment phase, number of injection phases; - duration of each injection phase; - duration of each stop phase without injection, if applicable; number of injection operations during each injection phase; - duration of the period separating two injection operations, - quantity of product injected at each injection operation.

Advantageously, in order to determine the conditions of evaporation and liquid injection, the method comprises a step of determining a quantity representative of a rate of elimination of the product or products within the product. closed chamber, and a step of selecting evaporation and liquid injection conditions according to the representative representative quantity.

Indeed, the product injected inside the enclosure is consumed in different ways: - a part is absorbed by the plant products, in the case of a phytosanitary treatment; a part is deposited on the internal surfaces of the closed enclosure; a part is evacuated towards the outside of the closed enclosure, in the case where there are leaks causing a circulation of air from inside the closed enclosure towards the outside of the closed enclosure; - A part absorbed in the air treatment system of the closed chamber, when it is equipped with such a system.

Indeed, the air treatment systems may include activated carbon filters that trap a portion of the product of the internal atmosphere. Likewise, closed enclosures, especially storage rooms for plant products, are typically refrigerated. Condensation occurs in the heat exchangers to cool the internal atmosphere of the closed chamber, the product partly dissolving in the condensed moisture.

It should be noted that the rate at which each product is absorbed by the plant products depends on the ambient temperature inside the closed enclosure. The determination step makes it possible to determine the magnitude representative of the removal rate of the or each product taking into account all the above parameters.

Typically, this step is performed experimentally, making measurements of the type shown in Figures 7 and 8.

In the example shown in Figure 7, an amount of a pure alcohol is evaporated and injected into a closed chamber, which is here a desiccator. The desiccator has a volume of 9 liters, and is maintained at a temperature of 7 ° C. The amount of alcohol injected is 0.01 ml. Curve 1 corresponds to a first test, in which the desiccator contains 1 kg of vegetable product. In this figure, the time expressed in hours is on the abscissa, and the concentration of gaseous alcohol, expressed in ppm, is on the ordinate.

Curve 2 corresponds to a test where the desiccator is empty, and does not contain any plant product. It is done under the same conditions as the test corresponding to curve 1.

Curve 1 shows that at the end of the evaporation phase, the concentration of gaseous alcohol is slightly greater than 300 ppm. The evaporation phase lasts about two hours. Then, in a second phase, the concentration of gaseous alcohol rapidly decreases to about 100 ppm after eight hours. In a third phase, the concentration of gaseous alcohol decreases more slowly. After fifteen hours, the amount of gaseous alcohol is less than 50 ppm. Thus, during the second phase, the rate of elimination of the alcohol is of the order of 35 ppm / h.

Curve 2 shows a gaseous alcohol concentration of about 400 ppm at the end of the evaporation phase. The gaseous alcohol concentration then decreases steadily, with a lower slope than for the first curve. The slope is then about 12 ppm / h. The difference between these two curves makes it possible in particular to determine the quantity of alcohol absorbed by the plant products as a function of time.

During the second phase of curve 1, this speed is of the order of 23 ppm / h.

Figure 8 illustrates similar tests to those shown in Figure 7. The only difference is that the amount of alcohol injected for the tests shown in Figure 8 is ten times greater than the amount of alcohol injected for the tests shown on FIG. 7 is injected, for the tests of FIG. 10, 0.1 ml of pure alcohol into the 9Lt desiccator.

The curves of FIG. 8 have substantially the same shape as the curves of FIG. 7. On curve 1, corresponding to the case where the desiccator comprises 1 kg of plant products, during the second phase, the speed of elimination of the gaseous alcohol is about 50 ppm per hour. The rate of removal of the gaseous alcohol for curve 2, corresponding to the case where the desiccator is empty, is about 22 ppm / h. Thus, during the second phase, plant products absorb about 28 ppm of gaseous alcohol per hour. At the selection step, the above results are used to choose the conditions of evaporation and liquid injection. These conditions are those listed above.

For example, these conditions may be chosen to maintain the concentration of alcohol in the internal atmosphere of the enclosed enclosure within a certain range. In the example illustrated in Figures 7 and 8, the range could be 100 ppm-1000 ppm. The conditions chosen would be to make an injection of 0.1 ml of alcohol in the desiccator every 18 hours, or an injection of 0.01 ml of alcohol in the desiccator every 8 hours.

Alternatively, the evaporation and injection conditions may be selected to maintain the rate of absorption of the alcohol in the plant products within a predetermined range.

This can be done by first determining a representative quantity of the rate of absorption of the alcohol in the vegetable products, then by choosing the evaporation and injection conditions according to the representative quantity thus determined.

In the examples shown in Figures 9 and 10, it is possible to maintain a rate of absorption in plant products between 20 and 30 ppm / h by performing an injection of 0.01 ml of alcohol every 8 hours, or with an injection of 0.1 ml of alcohol every 18 hours.

According to an embodiment illustrated in FIG. 7, the treatment method is a phytosanitary treatment method. The closed enclosure is a room or a silo or a storage room 4 of plant products. The closed chamber 4 comprises an air treatment system 5, for maintaining the temperature of the internal volume of the closed chamber 4 in a predetermined range. Typically, this temperature is between 0 ° C and 10 ° C.

Plant products 6 are typically fruits or vegetables.

For example, plant products are fruits such as apples, pears, grapes, pomegranates, etc.

In another example, vegetable products are vegetables such as potatoes, or broccoli, for example.

According to a third example the products are dry products such as wheat, rice, lentils, almonds.

The plant products 6 are in direct contact with the air filling the closed chamber 4. The vaporized liquid is injected directly into the internal volume of the closed chamber 4.

The method therefore comprises a step of storing plant products in the closed chamber 4, during a storage period DS of between 3 days and one year. The treatment step is concomitant with the storage step, as illustrated in FIGS. 2 to 5.

The DS storage duration and the DT processing time are as described above.

According to a first variant embodiment, the storage duration DS is short, between 3 days and 1 month. This case corresponds to the phytosanitary treatment of wheat in silos, citrus fruits, stone fruits such as peaches. The duration DT of the treatment step is typically between 3 days and 1 month. The method comprises a single injection phase of duration of between 3 days and 1 month, typically with one injection per day.

According to a second variant embodiment, the storage duration DS is long, typically between 3 months and 1 year. This case corresponds to the phytosanitary treatment of potatoes for long-term storage, for example. The processing time DT is substantially equal to the storage duration DS.

According to a first approach, the method comprises a single injection phase of duration PI substantially equal to the duration of treatment, typically with one injection per day.

According to a second approach, the method comprises several injection phases separated by stop phases without injection (as illustrated in FIG. 5).

The respective PI and PA durations of the injection and stopping phases are, for example: 3 days of injection with one injection per day, followed by 27 days without injection; - 7 days of injection with one injection per day, followed by 23 days without injection; -10 days of injection with one injection per day, followed by 20 days without injection.

The number of days of injection is determined according to the total amount of product to be injected, as well as the number of days of contact and the threshold dose to have the desired activity.

For example, for the injection of 1 liter of 2-ethylhexanol on potatoes stored for 6 months, it is possible: - to inject 5.5 ml / tonne of potatoes daily; - to inject 3 days per month 55 ml / ton; - to inject 7 days a month 24 ml / ton.

The preferred solution corresponds to the injection of low daily doses.

The following examples are given by way of illustration and not limitation of the invention.

Examples

Example 1

Potatoes were stored in 10L desiccators at room temperature for 18 days. On the first day, 100 μL of composition were introduced into the desiccators and then, after 9 days, 100 μL were again introduced.

The compositions consisted respectively of the alcohols listed in the table below. The compositions were vaporized as follows: for these small scale tests, the liquid product was deposited on cotton which was placed in the bottom of the desiccator. At room temperature and atmospheric pressure, the concentration can only be lower than the saturation concentration. Once the saturation is reached, the product does not evaporate anymore [sci].

The witness desiccator did not have a composition.

The C3-C9 alcohols, and especially C6-C8 alcohols, thus have a potentiated decrease in the amount of the seeds relative to the control.

Example 2

Potatoes are stored in a closed chamber at a temperature of about 7 ° C to 9 ° C. The following treatments are carried out: (i) A C3-C9 alcohol is evaporated and injected into the closed chamber.

Typically, this liquid is 2-ethylhexanol. In this case, the treatment time is about 6 months. The treatment step comprises a single injection phase, of duration substantially equal to the treatment duration. An injection operation is carried out each day, the total quantity of liquid injected during the 6 months being between 100 and 2000 ml of liquid per ton of potatoes, preferably between 600 and 1200 ml per ton of apples. earth, and worth for example 1000 ml per ton of potatoes. (ii) A C3-C9 alcohol is evaporated and injected into the closed chamber.

Typically, this liquid is 2-ethylhexanol. In this case, the treatment time is about 6 months. The treatment step comprises several injection phases, separated by stop phases without injection. Each injection phase lasts between 3 days and 2 weeks, typically one week. The duration of each stop phase is approximately 3 weeks. During each injection phase, an injection operation is performed every day, the quantity of liquid injected being between 5.5 and 110 ml / day ml of liquid per ton of potatoes, preferably between 33 and 67 ml / day per ton of potatoes, for example 55 ml / day per ton of potatoes. The total amount injected within six months is approximately equal to that of Example i).

Claims (15)

1. - A method of treating plant products comprising evaporation of a liquid composition comprising a C3-C9 alcohol, and characterized in that said process comprises the application of alcohol vapor at a concentration lower than the concentration of saturation of the alcohol in the atmosphere on said plant products. 2. - Process according to claim 1, wherein said alcohol is chosen from isopropanol, butanol, amyl alcohol, hexanol, heptanol, 2-ethylhexanol, 2-octanol, 1-octanol, isooctanol, nonanol, and their C3-C9 isomers and mono-unsaturated C3-C9 alcohol equivalents. 3. - Process according to claim 1 or 2, such that said alcohol is selected from alcohols C6-C8. 4. - Method according to claim 1, 2 or 3, characterized in that said process is biocidal, safener and / or anti-germinative. 5. - Method according to any one of the preceding claims, characterized in that said plant products are potatoes. 6. - Process according to any one of the preceding claims, such that said composition comprises another biocide active ingredient, phytoproteceur and / or antigerminatif. 7. - Method according to claim 6, wherein said active ingredient is selected from clove, mint, rose, thyme, oregano, cinnamon, eucalyptus essential oils. 8. - Method according to claim 7, wherein the active principle is chosen from L-carvone, eugenol, geraniol, thymol, carvacrol, cinnamaldehyde, eucalyptol, dimethylnaphthalene, 3-decene, 2-ne, hexanal, pyrethrum, synthetic pyrethrins and volatile synthetic biocides. 9. - Process according to any one of the preceding claims, such that the alcohol is applied at doses of between 1 and 100g / tonne per day. 10. - Method according to any one of the preceding claims, such that said composition further comprises at least one organic solvent, and / or one or more excipients. The method of any one of the preceding claims which comprises the following steps; absorption of the liquid by an absorption member (16); producing a flow of gas, the flow of gas being directed towards the absorption member (16); and evaporation of the liquid at a temperature below 50 ° C. 12. - Process according to any one of the preceding claims, such that said evaporation is carried out by a device for evaporation of a liquid, the device comprising: - - a vaporizer (18) configured to evaporate a liquid containing the or each produced at a temperature below 50 ° C, and for injecting the vaporized liquid into a closed enclosure (2, 4); an electronic device (20) for controlling the vaporizer (18), programmed to implement a duration treatment step (DT) greater than or equal to 3 days, the treatment step comprising at least one injection phase of a duration greater than or equal to 3 days during which the vaporizer (18) evaporates the liquid and injects the vaporized liquid with a period of less than two days. The method of claim 12 such that the vaporizer (18) comprises; - a reserve (22) containing the liquid; - a member (24) for absorbing the liquid; and - a member (26) for producing a gas flow, the flow of gas being directed towards the absorption member. 14. The method of claim 13 wherein the absorption member (24) comprises a plurality of absorbent strips (28) adapted to retain the liquid. 15. - Method according to claim 12, characterized in that the vaporizer (18) comprises a tower (40) having a lining (42), a device (44) for injecting the liquid above the lining (42), and a device (46) arranged to create an upward flow of air through the liner (42).