METHOD FOR OBTAINING A PRODUCT IN THE FORM OF DEEP-FROZEN, DISSOLVED-GAS-RICH GRANULES, PARTICLES OR BEADS, AND ASSOCIATED EQUIPMENT

Abstract

The invention relates to a method and associated equipment for obtaining a product in the form of deep-frozen, dissolved-gas-rich granules, particles or beads from a liquid, semi-liquid or pasty matrix (2), comprising the following steps: gasification of the matrix (2) by incorporating a gas; dispensing the matrix (2) in the form of drops; and cryogenically freezing the matrix drops by immersion in a cryogenic fluid (70), the step of gasification of the matrix (2) involving dissolving a large amount of the gas generated by the evaporation of the cryogenic fluid in the drops by increasing the number of gas molecules in a high gas density zone, called high molecular density zone, located above the surface of the cryogenic fluid and on the path of the matrix drops before they are immersed in the fluid.

Claims

1. A method for obtaining a product in the form of deep-frozen, dissolved-gas-rich granules, particles or beads from a liquid, semi-liquid or pasty matrix (2) comprising the steps of gasifying the matrix (2) by incorporating a gas, dispensing the matrix (2) in the form of drops and cryogenizing the matrix drops by immersion in a cryogenic fluid (70), characterized in that the step of gasification of the matrix (2) consists in dissolving in large quantities the gas generated by the evaporation of the cryogenic fluid in the matrix drops so that the product is at least saturated with said gas, the dissolution being carried out by increasing the number of gas molecules in a zone of high gas density, called a high molecular density zone, located above the surface of the cryogenic fluid and on the path of the matrix drops before their immersion in the fluid, said high molecular density zone being created by carrying out the gasification and cryogenization of the gasified drops within a closed chamber provided with a vent (8) arranged to allow evacuation of the gas generated by the evaporation of the cryogenic fluid by natural convection and to keep the inside of the chamber at a pressure greater than or equal to atmospheric pressure.

2. The method according to claim 1, characterized in that the gasification step is carried out at a pressure greater than or equal to atmospheric pressure.

3. The method according to claim 1 or claim 2, characterized in that the gasification and cryogenization steps of the gasified drops are carried out in the same closed chamber provided with at least one exhaust vent, sized to allow the evacuation of the gas generated by the evaporation of cryogenic fluid by natural convection.

4. The method according to any of the preceding claims, characterized in that it comprises a step of continuous or semi-continuous collection of the supersaturated granules, particles or beads.

5. Equipment (1) for obtaining a product in the form of deep-frozen, dissolved-gas-rich granules, particles or beads from a liquid, semi-liquid or pasty matrix (2), comprising means for dispensing the matrix (2) in the form of drops and a cryonics receptacle (7) containing a cryogenic fluid (70) in which the matrix drops are received in order to be cryogenized and transformed into supersaturated granules, particles or beads, characterized in that the equipment (1) comprises a high gas molecular density zone (6) located between the means for dispensing the matrix (2) in the form of drops and the cryonics receptacle (7), the high gas molecular density zone (6) and the cryonics receptacle (7) being located inside a closed chamber (10) provided with at least one exhaust vent (8) for evacuating the gas generated by the evaporation of the cryogenic fluid (70) by natural convection, the vent (8) being arranged to keep the inside of the chamber (10) at a pressure greater than or equal to atmospheric pressure.

6. Equipment (1) according to claim 5, characterized in that the cryonics receptacle (7) is located under the means for dispensing the matrix (2) in the form of drops so as to receive the matrix drops (3) by gravitational flow from the means for dispensing the matrix (2) in the form of drops into the cryonics receptacle (7).

7. Equipment (1) according to claim 5 or claim 6, characterized in that the means for dispensing the matrix (2) in the form of drops are located inside the chamber (10).

8. Equipment (1) according to any of claims 5 to 7, characterized in that it comprises a collection device of the granules, particles or beads at the outlet of the cryonics receptacle (7).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0025] Other objects and advantages of the invention will become apparent from the following description, made with reference to the accompanying drawings, in which:

[0026] FIG. 1 is a schematic view of equipment according to the invention for obtaining a product in the form of deep-frozen, dissolved-gas-rich granules, particles or beads, from a liquid, semi-liquid or pasty matrix;

[0027] FIG. 2 is a schematic representation of the operating principle of the equipment of FIG. 1;

[0028] FIG. 3 is a schematic view of the measuring device used to measure the quantity of gas present in the matrix beads obtained according to various tests.

DETAILED DESCRIPTION OF THE FIGURES

[0029] FIGS. 1 and 2 respectively show a schematic view of equipment 1 and its operating principle for obtaining a product in the form of deep-frozen, dissolved-gas-rich granules, particles or beads, from a liquid, semi-liquid or pasty matrix.

[0030] The equipment 1 comprises means 5 for dispensing the matrix in the form of drops 3, a cryonics receptacle 7 containing a cryogenic fluid 70 and in which the matrix drops 3 are received to be cryogenized and transformed into granules, particles or beads containing the dissolved gas.

[0031] The cryonics receptacle 7 is arranged under the means 5 for dispensing the matrix in the form of drops so that the matrix drops 3 at the outlet of said means 5 fall under gravity into the cryonics receptacle 7.

[0032] The equipment 1 further comprises a high gas molecular density zone 6 located between the means 5 for dispensing the matrix in the form of drops and the cryonics receptacle 7.

[0033] The means 5 for dispensing the matrix in the form of drops, the high gas molecular density zone 6 and the cryonics receptacle 7 are arranged inside a closed chamber 10 provided with an exhaust vent 8 to evacuate the gas generated by the evaporation of the cryogenic fluid 70. It is of course possible to provide several gas exhaust vents without departing from the scope of the invention. In the example described, the vent 8 is arranged to maintain the inside of the chamber 10 at a pressure equal to atmospheric pressure. The vent 8 is arranged to allow evacuation of the gas by natural convection. However, for special needs, means may be provided for closing the vent in order to pressurize the chamber 10.

[0034] The equipment 1 further comprises a device 9 for extracting the cryogenized granules, particles or beads. The extraction device 9 is configured to maintain the sealing of the chamber 10, preventing the gas contained in the chamber 10 from escaping. The extraction device 9 may be, for example, an airlock or bucket wheel system, the airlock or the buckets preventing the escape of gas other than that present with the beads or granules in the airlock or buckets.

[0035] The extraction device 9 is connected to a collection device (not shown) located outside the chamber 10.

[0036] FIG. 2 shows a diagram of the operating principle of the equipment according to the invention. The matrix 2 to be treated flows through a shower 5, so as to form drops 3 which fall into the cryogenic fluid 70. During their fall, the drops 3 pass through the increasingly high gas molecular density zone 6, generated by the boiling cryogenic fluid 70. This increasing density allows a strong dissolution of the gas in the matrix 2. In particular, the maximum dissolution is reached as close as possible to the bath of cryogenic fluid 70, where the molecular density is greatest. The high gas density zone is created as soon as a permanent regime settles within the chamber 10, which is reached due to the diffusion of the gas by natural convection towards the outside of the chamber, only through the vent 8. The molecular density gradient applied to the product drops, influencing the quantity of gas incorporated therein, is linked to the sizing of the chamber itself, but also to the pressure which develops therein.

[0037] After an immersion time in the cryogenic fluid 70 sufficient for the drops 3 to become fully solid beads, the latter are extracted from the chamber 10 by a dedicated system of the airlock type consisting, for example, of two valves which are not open at the same time, or a bucket wheel, making it possible to prevent the gas from escaping continuously in the room where the machine is located.

[0038] The granules, beads or particles are then placed in a package, then stored at a temperature sufficient to ensure that the product remains solid, depending on its melting temperature. The storage temperature may thus vary from −18 to −80 degrees Celsius, depending on the initial composition of the matrix. For example, most food matrices can be stored at −18° C.

[0039] Comparative Tests

[0040] Tests carried out under different conditions of implementation are presented below, test 2 corresponding to the method according to the invention.

Test 1: Water beads cryogenized under pressure are produced according to the method described in application WO2008/043909, under a 4 bar pressure, in equipment 1 as described above, but whose vent 8 has been closed. The chamber 10 is thus completely closed. The gas incorporation operation is carried out in the matrix 2, before passing through the shower, by bringing said matrix 2 into contact with an atmosphere whose partial gas pressure is also equal to 4 bars. The beads are stored for 48 hours in a home freezer, at a temperature of −18° C. The amount of gas present in the beads is then measured using a device 20 illustrated in FIG. 3 and described below. To this end, 200 g of beads are placed in a first sealed container 21. An advantageously flexible pipe 22 is connected to the container and is immersed in a second container 23 containing water 24, so that bubbles escaping from the pipe go up into a measuring cylinder 25, also filled with water and placed upside down. When the beads have thoroughly melted in the first container, the volume of gas initially contained in the beads corresponds to the volume of gas 26 that appeared in the measuring cylinder.
Test 2: Cryogenized water beads are produced in the same equipment 1 as above, but without pressure, and with only the vent 8 open. With the exception of the vent 8, chamber 10 is fully enclosed. During the treatment, the pressure observed in chamber 10 is indeed 0 bar. The beads are stored for 48 hours in a home freezer, at a temperature of −18° C. The amount of gas present in the beads is then measured using the device 20 of FIG. 3.
Test 3: Cryogenized water beads are made in the same equipment 1 as above, but without pressure and with air suction through the open vent 8. With the exception of vent 8, chamber 10 is fully enclosed. The beads are stored for 48 hours in a home freezer, at a temperature of −18° C. The amount of gas present in the beads is then measured using the device 20 of FIG. 3.
Test 4: Water beads are produced outside the device, in the form of drops using a syringe above a dewar filled with liquid nitrogen. The beads are stored for 48 hours in a home freezer, at a temperature of −18° C. The amount of gas present in the beads is then measured using the device 20 illustrated in FIG. 3.
Test 5: Water ice cubes are made by conventional freezing, by filling the hemispherical cells of a mold before placing the latter in the freezer at −18° C. After 48 hours, the beads are unmolded and the amount of gas present therein is measured using the device 20 illustrated in FIG. 3.

[0041] The results obtained are given in Table 1 below:

TABLE-US-00001 Equivalent Volume of gas pressure Test number measured (ml) (bars) 1 16 3.5 2 6 1.5 3 0 0 4 0 0 5 0 0

[0042] It is observed that no gas is present in the products when they are prepared outside any specific equipment or in equipment having a suction of the gas generated. Indeed, Tests 3, 4 and 5 do indeed make it possible to obtain beads, but they contain absolutely no dissolved gas.

[0043] It is also observed that the method according to application WO2008/043909 (incorporation of gas under a pressure of between 2 and 10 bars) makes it possible to obtain products containing dissolved gas in large quantities. Indeed, Test 1 does indeed allow a large quantity of gas to be measured, necessarily obtained by supersaturation of the product.

[0044] Finally, it is observed that the method as described in the present application, corresponding to Test 2, also allows gas to be dissolved in the products, so that a supersaturation is also observed. In this example, the quantity of gas observed in Test 2 is appreciably less than that obtained in Test 1. This is explained by the small dimensions of the treatment device used, which only makes it possible to generate a low gradient gas molecular density and a limited dissolution of the latter in water. It can therefore be seen that by carrying out the step of incorporating gas in the drops 3 of the matrix and not on the matrix 2, and by simply applying a molecular density gradient, a supersaturation of the drops 3 is observed. The equivalent pressure calculated in Table 1 corresponds to the pressure to which the product should have been subjected to obtain the measured gas dissolution. A pressure of 3.5 bars is indeed calculated for the product which was subjected to a 4 bar pressure (the dissolution was not complete but it is all the same significant, of the order of 88%). An equivalent pressure of 1.5 bars is also calculated for the product which was not subjected to any pressure, which confirms the existence of a supersaturation under the effect of the high gas molecular density generated above the nitrogen bath.

[0045] The invention is described in the foregoing by way of example. It is understood that a person skilled in the art is able to achieve different embodiments of the invention without departing from the scope of the invention.