The present invention relates to a new process of carbonation. The invention also includes a suitable system for carrying out the new process, denoted by the term carbonator. Carbonation is a process by means of which carbon dioxide, Co ₂ , is incorporated into a product, usually in an aqueous liquid. It is used especially for the production of carbonated beverages, a general designation which includes carbonated waters, carbonated fruit juices, colas and carbonated cooling drinks in general, as well as carbonated wines.

The carbonated products may be for example water, mineral waters, aqueous solutions containing extracts of fruits or other vegetable extracts, especially of cola, tea or coffee, sugar or other sweeteners, caramel, citric acid, ascorbic acid, colorants and, generally in small concentrations, inorganic anions and cations such as bicarbonate, chloride, fluoride, sodium, calcium, potassium, magnesium, etc. They may also contain alcohol, in the case of wines, flavourings, colorants, thickeners, dispersants and solid products in suspension, normally vegetable fibres and fruit pulps or others. Naturally, for the preparation of beverages, all of the above-mentioned components or additives should be of alimentary grade.

In addition to the case of the preparation of beverages, carbonation may also be applied in other fields, for example for pH adjustment in liquids or others. Carbonation is a complex process which comprises the physical phenomena of dispersal and dissolution of C0 ₂ in the liquid medium together with chemical phenomena of interaction of C0 ₂ first with the water, forming unstable carbonic acid, and subsequently with other components of the medium to be carbonated, giving rise to carbonates and other compounds which play a part in the fixation of C0 ₂ .

Carbonation processes are known at the present time and are very widely diffused in industry, principally in the

food-industry sector and especially in the industry for the preparation of non-alcoholic beverages.

These known carbonation processes can be classified generally as two technical variants: 1) carbonation in saturators; and

2) carbonation in pressure vessels

In the technique (1) of carbonation in saturators, diffusion of gaseous carbon dioxide throughout the liquid to be carbonated is promoted. Saturators are devices in which a C0 diffuser is located in a reactor, generally of tubular form, into which a liquid to be carbonated is passed in a continuous manner. This diffusion is effected by causing gaseous C0 to pass under slight pressure through the diffuser, dispersing it throughout the liquid to be carbonated. Diffusers are normally devices which have, in their terminal part in contact with the liquid, a porous plate which can be made from various materials, such as for example porous porcelain, porous metal plates, etc. Porous tubes can also be used as diffusers, for example metal tubes which are inserted inside the saturator, normally of concentric tubular form. The pressure of C0 ₂ should be sufficient to provide an adequate flow of C0 ₂ to overcome the resistance of the porous diffuser and the pressure of the particular fluid to be carbonated. In a technical variant, the saturator is of Venturi type and the C0 is introduced immediately upstream of the constriction or at the entry to it, thereby obtaining a more rapid incorporation owing to the variation in pressure caused by the Venturi effect. In another known technique of carbonation (2) , a pressure vessel is used. In accordance with this technique, the vessel is charged with gaseous C0 up to a high pressure,

5 which may usually be from 5 to 6 10 Pa. Then the liquid to be carbonated is introduced into the vessel by means of calibrated perforations which produce fine jets. The intimate contact thus effected between the C0 present within the vessel and the liquid introduced promotes the incorporation of the C0 ₂ into the liquid. In order to maintain the

efficiency of the process it is usual to replace the C0 ₂ consumed to keep pace with its absorption by the liquid, in such a way as to maintain the working pressure.

Some improvements have been introduced into the above- mentioned carbonation processes, but in general these improvements do not substantially change the essential nature of the processes and relate, above all, to matters of detail.

J60087837 describes a system for the carbonation of liquids, especially beverages, in which gaseous C0 ₂ is atomized within a liquid under reduced pressure, a high efficiency of carbonation being claimed.

DE 4319526 describes an apparatus for carbonation which allows a uniform and controllable level of carbonation by using a control unit when C0 ₂ is introduced. WO 9415489 describes a process of carbonation of mineral water in which, after a conventional carbonation with gaseous C0 ₂ , PET bottles are filled with the cooled water and a specific quantity of solid C0 ₂ is added to each bottle, these being closed as rapidly as possible. Clearly, this process is not suitable for industrial use.

DE 3634814 describes a method of carbonation of liquids, especially non-alcoholic beverages, in which gaseous C0 is added in a zone of low pressure from an injector.

DE 3431906 describes a system for the saturation of liquids with a gas, especially C0 , which makes use of a porous membrane.

EP-145918 describes a process for rapid carbonation of water by means of a controlled flow of gaseous C0 ₂ .

DD-211489 describes a system for the carbonation of liquids, for example lemonade, in which the C0 ₂ /air mixture is recycled, allowing an saving in the use of C0 .

WO 8400671 describes an automatic system for the carbonation of liquids for beverages, in which the introduc¬ tion of gaseous C0 into the carbonation chamber is effected via a valve controlled automatically.

DE 3132706 describes a system for the carbonation of beverages in which the liquid for carbonation and the C0 are made to pass in contraflow through a series of storage tanks.

The production of sparkling wines by carbonation is the subject of processes described, for example, in SU 1082803 and SU 1124019, gaseous C0 being used in both cases.

Obtaining carbonated beverages for immediate use in restaurants or for domestic consumption is the subject for example of WO 9015011, EP-296570, GB 2186265, GB 2137894, BE- 898455, WO 8204243, GB 2097274, EP-59534, BE-878003, BE-877855 and EP-33157. All of these systems utilize gaseous C0 ₂ , introduced by various means and under different conditions into a stream of the liquid for carbonation when the latter is tapped from a storage reservoir into a receptacle for immediate consumption, for example into a glass.

The process of carbonation is influenced especially by the operating pressure, by the temperature and also by the pH in particular and by the composition in general of the liquid medium. The pressure and temperature at which the carbonated product is going to be stored until the moment of use must also be taken into account, bearing in mind that this storage is normally effected in plastic, glass or metal, generally aluminium, containers. These containers are sealed by crown pressure caps, by screw caps or, in the case of so-called cans, they are punched and equipped with devices for easy opening formed by a tear-away groove with a ringpull for the action of opening.

In any case, the greater part of the C0 ₂ , whether dissolved or combined, is found in the carbonated product in equilibrium at a certain pressure, but can be easily liberated once this equilibrium is disturbed, usually by a reduction in the pressure, which may occur simply as a result of opening the container in which the carbonated product is stored under a slight pressure and of placing the liquid at atmospheric pressure. If the material of the container is partially permeable to C0 , as is the case with certain plastic materials used for bottles for beverages, there may be a tendency for a gradual loss of C0 over time.

All of the known industrial processes for carbonation of liquids have in common the fact that they are carried out in a single operation and make use of gaseous carbon dioxide. In general, to obtain an acceptable degree of carbon- ation the pressure of C0 ₂ should be elevated. The improved processes referred to above cite pressures of 0.22 to 5.2 MPa or refer to "high pressure".

Usually, the incorporation of C0 ₂ is facilitated by using a low temperature, to which the liquid is in general cooled by means of refrigerating units or heat exchangers, which involves considerable investments.

On the other hand, because the provision of C0 ₂ to industry in appreciable quantities is usually made in cryogenic storage tanks in which the C0 ₂ is present in the liquid state, these processes also involve the existence of gas atomizers which are normally atmospheric heat exchangers provided with coils of flanged tubes, which also raises the cost of the system. The alternative of utilizing gaseous C0 provided in pressurized metal cylinders has the disadvantages of being more expensive and of requiring more labour for transporting, positioning and connecting the cylinders and for activating the individual valves, which is unacceptable since it is unsuitable for domestic use or use in restaurants or even in small trials on a laboratory scale. Beverages carbonated by the conventional processes exhibit a reduced degree of fixation of C0 in the liquid, which presents two principal disadvantages. In the first place, in the case of beverages or other liquids packaged in materials partially permeable to C0 ₂ , a gradual loss of gas through the wall of the container occurs, which reduces the shelf life of the product, with very deleterious economic consequences. This gradual loss is very appreciable, especially in the case of PET bottles. Nevertheless PET is tending to become ever more prevalent as the material of choice for the packaging of gasified beverages, its use for this purpose having experienced a spectacular increase of 80% between 1992 and 1995 in the European market. In the US market, owing to restrictions on the use of PVC, the use of

PET has become general and in the Japanese market the trend is in the same direction. The disadvantage, however, of the permeability of PET to gases, and especially to C0 , has led to research into the development of mixed packaging or of alternative materials such as polyethylene naphthalate (PEN) , which is, however, ten times as expensive.

On the other hand, defective fixation of C0 ₂ also represents an major disadvantage at the time of consumption. Once the packaging is opened, the C0 ₂ tends to be released in the form of bubbles, which contributes to the flavour of the product. However, the release is in general too rapid, which has the result that a beverage which is not consumed quickly does not ultimately give the same degree of satisfaction. The subject of the present invention is a new process of carbonation which differs completely from the conventional processes described in terms of implementation and results.

A further subject of the invention is a suitable apparatus for implementing the new process, denoted by the term carbonator, and a system for industrial use in which the apparatus of the invention is linked to auxiliary devices which enable all of the operations to obtain carbonated liquids, especially carbonated beverages, to be carried out. The new process of carbonation of the present invention may be used for all the cases in which use has been made hitherto of the conventional carbonation techniques described, especially for the production of carbonated beverages in general, carbonated waters, carbonated fruit juices, colas and other carbonated cooling drinks, as well as carbonated wines. However, the use of the process of the present invention is not necessarily limited to the field of beverages.

The process of the present invention is characterized in that it comprises at least one stage of carbonation or of prior carbonation in which use is made not of gaseous carbon dioxide but of carbon dioxide in liquid form, thereby promoting dissolution of C0 throughout the liquid which it is intended to carbonate at a moderate pressure by means of

the intimate contact of the liquid carbon dioxide with the liquid for carbonation atomized into fine droplets.

Preferably, for this purpose, the liquid for carbonation and the liquid C0 ₂ are simultaneously atomized in a closed container which has suitable devices for the atomization of the liquid for carbonation and of the liquid

C0 . This container is termed a carbonator.

In a particular case of special interest, the process of the present invention can be carried out in two stages, a pre-carbonation and a subsequent post-carbonation, utilizing, in the pre-carbonation stage, carbon dioxide in liquid form as described above. The liquid may then be subjected to a conventional post-carbonation, to complete the process. In this particular case, the first stage of pre-carbonation is carried out in a container such as that described, in this case termed pre-carbonator, and the subsequent stage is carried out in a conventional post-carbonator.

This particular two-stage case is preferred when preparing carbonated beverages whose composition includes syrups, these being introduced for example in a mixer inserted between the pre-carbonator and the post-carbonator.

The new process of carbonation consists in the incorporation of C0 ₂ into a liquid for carbonation in a carbonation chamber, use being made, for this purpose, of liquid C0 ₂ which is brought into intimate contact with the aforementioned liquid at moderate pressure.

Preferably, the C0 is atomized inside the chamber in which the liquid for carbonation is also atomized, so that the paths of the two fluids intersect. In accordance with the particular two-stage case, the new process of carbonation consists in the incorporation of C0 ₂ into the liquid for carbonation in two consecutive stages carried out in two different chambers, namely pre-carbonation and final post-carbonation, liquid C0 ₂ being utilized in the first stage in the pre-carbonator in which it is brought into contact with the liquid for carbonation, preferably in such a manner that the streams of the two fluids intersect, as described. In turn, the subsequent stage of final post-

carbonation may be carried out in accordance with the conventional techniques of carbonation, except that the liquid for carbonation, which has previously been subjected to pre-carbonation, contains, already incorporated, an appreciable quantity of carbon dioxide, as a result of which the operation is in general more rapid and less critical than conventional carbonation.

The carbonator or pre-carbonator in accordance with the technique of the present invention is formed by a chamber or container in which there are different nozzles for injecting liquid C0 ₂ , on the one hand, and the liquid for carbonation on the other. In this chamber, the liquid for carbonation is atomized by means of injectors in sufficient number for the volume which it is intended to treat. This atomization converges in the centre of the chamber. Meanwhile there is introduced into the chamber a stream of liquid C0 ₂ which, under the working conditions of temperature and pressure, is ultimately converted into dry ice, i.e. into solid C0 ₂ in subdivided form and, in this case, finely divided form. The stream of C0 ₂ intercepts the various atomizations of the liquid, cooling it and combining with it.

In accordance with a preferred embodiment of the process of the present invention, a constant injection of liquid C0 ₂ is created via the atomization apertures so as to form a vertical downward stream of C0 ₂ . The C0 is converted immediately into dry ice even before coming into contact with the liquid for carbonation. At the same time, the liquid intended for carbonation is injected via the injectors arranged in several rows placed at various heights so as to form in the interior of the carbonator or of the pre- carbonator jets whose paths are initially horizontal, in such a way as also to atomize the liquid. The jets of C0 ₂ and of the liquid for carbonation intersect, resulting in a fine dispersion or incorporation of the carbon dioxide into the liquid.

The entire process may be carried out in an atmosphere with controllable pressure and temperature, thus permitting various degrees of incorporation of C0 into the liquid. The

usual pressure of the process is only from approximately 200 to approximately 4000 hPa (relative pressure) , a moderate pressure when compared with the pressures generally necessary for conventional carbonation. The introduction of the liquid C0 is preferably effected from a cryogenic reservoir at a pressure of 1.5 to 2.5 MPa, and the diameter of the inlet apertures is a function of the volume to be treated and of the pressure. Moreover, the diameter of the injection apertures for the liquid for carbonation is also a function of the volume to be treated and of the nature of the liquid.

The temperature of carbonation of the process of the present invention is preferably a temperature below the ambient temperature, suitable temperatures being between approximately 4°C and approximately 15°C. Normally it is possible to attain a suitable temperature for the process without having recourse to refrigerating units for cooling the carbonator and the liquid for carbonation, taking advantage only of the cooling arising out of the use of cryogenic C0 ₂ and its expansion during the process.

After the pre-carbonation the liquid may be subjected to a conventional post-carbonation to complete the process, augmenting the quantity of dissolved C0 .

In any case, the liquid to be treated in the stage of carbonation in accordance with the present invention or in pre-carbonation in the particular case of two stages should be free of solid particles or of dissolved components which could interfere with the process, for example by raising its viscosity, which could be the case with sweetners or others. If it is intended that a beverage should contain solids, be these fruit fibres or pulps, etc., or constituents such as those referred to, these must be added subsequently to the pre-carbonated liquid, between the stage of pre-carbonation and that of the final post-carbonation, for which a mixer may be inserted in the system of carbonation. This mixing may be effected by conventional techniques.

After the pre-carbonation and the optional mixing of the above-mentioned components, the liquid may be routed to a

post-carbonator in which a conventional carbonation is carried out by dissolving C0 ₂ under customary conditions of pressure and temperature, different from those utilized in stage 1. A further subject of the present invention is a suitable apparatus for carrying out the carbonation, comprising a carbonator as described below.

In particular a subject of the present invention is an appropriate system for carrying out a carbonation in at least two stages, comprising a pre-carbonator, a mixer if required, and a post-carbonator similar to a conventional carbonator.

The carbonator in accordance with the present invention or the pre-carbonator in the particular two-stage case comprises a reservoir made from suitable material which has sufficient separate inlet ports for the introduction of liquid C0 and of the liquid for carbonation and injectors for the atomization of these in a geometrical arrangement such that the jets intersect as described.

The carbonator or pre-carbonator can be of any form. A cylindrical form is suitable, the height being conveniently greater than the diameter. The bottoms may be flat, conical or domed, in accordance with usual practice in the case of the low-pressure reservoirs used in the food industry and in the chemical industry. Alternatively the form may also be prismatic, it being possible for the bottoms in this case to be flat or pyramidal.

The carbonator or pre-carbonator can be of any material compatible with the liquid to be treated and with the standards of cleanliness customary in the food industry. Preferably stainless steel is employed, although other materials may be employed, such as carbon steel, enamelled steel, polymeric materials, etc.

Preferably the pre-carbonator has external thermal insulation, which contributes to the economy of the process. The carbonator or pre-carbonator may advantageously be equipped with control, monitoring or safety instruments, such as, for example, controlled valves, for example pneumatic valves or electrovalves, for regulating the inlet and outlet

of fluids, level detectors, pressure and temperature gauges, inspection ports, safety valves, valves for the withdrawal of samples, etc. The pressure and temperature gauges may be of appropriate form, equipped with local indicators and/or signal transmitters for remote indicators and/or regulators, for example in a synoptic panel or control robot.

The mixer and the conventional post-carbonator, when present, may have the usual characteristics of these items of equipment. Figure 1 shows a carbonator or pre-carbonator in a non- limiting preferred embodiment. In this figure, the numerals denote the following:

1 - steel tank, preferably of stainless steel

2 - distribution cage for the liquid for carbonation 3 - liquid injectors

4 - pneumatically activated valves for decompression

5 - electrovalves for C0 ₂ in liquid phase

6 - electrovalves for C0 ₂ in liquid phase

7 - pneumatically activated valve for liquid inlet 8 - pressure transducer

9 - temperature transducer

10 - injectors for C0 ₂ in liquid phase

11 - pneumatically activated valve for liquid outlet

12 - electrovalve for withdrawal of liquid samples 13 - maximum level detector

14 - safety valve

15 - thermal insulation

Figure 2 shows an example of a system comprising a pre- carbonator, a mixer and a conventional post-carbonator. This figure shows the following:

PI, P2, P3 and P4 - pressure stats TI - temperature probe Nl, N2 and N3 - level probes Bl and B2 - pressurization pumps VI - valve for injection of liquid for carbonation V2 - valve for injection of liquid C0 ₂ V3 - decompression valve for the pre-carbonator V4 - outlet valve for liquid

V5 - by-pass valve to mixer

V6 - outlet valve for mixer

V7 - outlet valve for filling

V8 - outlet valve for post-carbonator V9 - inlet valve for gaseous C0 ₂

V10 -pressurization valve for post-carbonator

Vll - inlet valve for syrup

VS1 and VS2 - safety valves

V12 -inlet valve to mixer for precarbonated liquid. In an especially preferred embodiment of the system of the present invention, there is an automatic or computerized control in which the optimal parameters for each utilization have been previously established.

In an especially preferred embodiment, the system is computerized and has appropriate programs for each product.

The automated or computerized system may, for example, consist of a system similar to that represented in Figure 1 in which the valves 4, 5, 6, 7, 11 and 12 are controlled electrically or pneumatically by means of signals received from a robot, which in turn receives instructions derived from the measuring instruments 8, 9 and 13.

In the same way, in the case of the example of Figure 2, the automated or computerized system may, for example, consist of a system in which the valves VI and V12 and the pumps Bl and B2 are controlled electrically or pneumatically by means of signals received from a robot, which in turn receives instructions derived from the measuring instruments PI to P4, TI and Nl to N3.

The process of the present invention offers numerous advantages over the conventional process of carbonation, of which the following are notable:

There is a better fixation of the C0 in the liquid; Simultaneously with the carbonation, air is removed from the liquid, which also allows a better fixation of C0 ; As a consequence of this better fixation, the keeping- quality of the product during storage is improved and the shelf life of the carbonated products in accordance with the process of the present invention may be increased. Also owing

to this effect, packaging beverages carbonated by the present process, in PET, does not present the problem of rapid progressive loss such as occurs with beverages produced by the conventional process. In the particular case of the two-stage process, there are better conditions for absorption of C0 ₂ by virtue of the stage of pre-carbonation;

Another advantage of the process of the present inven¬ tion, also related to the better fixation of the C0 ₂ in the liquid, is the slower release of gas after the packaging has been opened, which allows enjoyment of the beverage without an adverse effect on the taste for a longer period of time, even after it has been poured out into the glass.

From an industrial point of view it should also be emphasized that this process eliminates the need for refrigerating units for cooling the liquid, inasmuch as the sole cooling is effected by the liquid C0 ₂ itself introduced into the process. Moreover, the utilization of cryogenic C0 ₂ does not presuppose the existence of evaporators. In this way the investment required is considerably reduced.

A further advantage of the process of the present invention is the moderate pressure at which it can be carried out, which allows the utilization of more economical equipment. An additional advantage of the present invention is the optional availability of a totally automated system in which all of the operations can be carried out in sequence with previously established parameters for an operation under optimal conditions. The system may be controlled by computer with previously designed programs suitable for each product.

The examples which follow are intended to illustrate the invention without, however, restricting its scope in any way.

Example 1: Preparation of carbonated water 100 of drinking water and 85 g of liquid C0 ₂ were introduced simultaneously into a carbonator similar to that shown in Figure 1, previously filled with gaseous C0 ₂ and cooled to about 7°C, via the respective valves and in such a

manner that the jets of the atomized fluids intersected inside the apparatus. The C0 was derived from a cryogenic reservoir at about -20°C and 2.0 MPa. The flows were adjusted in such a manner that the temperature during the process inside the carbonator was maintained at around 6.5°c and the pressure reached around 0.12 MPa. During atomization of the C0 ₂ , the latter was converted to dry ice by expansion, having cooled to around -76°C. The introduction lasted about 1 minute. At the end of the operation, the carbonated water was discharged via the discharge valve and immediately bottled. Example 2: Preparation of cola soft drink 100 L of drinking water and 100 g of liquid C0 ₂ were introduced simultaneously into a pre-carbonator of a two- stage carbonation system, similar to that shown in Figure 2, previously filled with gaseous C0 ₂ and cooled to around 6°C, via the respective valves and in such a manner that the jets of the atomized fluids intersected inside the apparatus. The C0 was derived from a cryogenic reservoir at about -20°C and 2.0 MPa. The flows were adjusted in such a manner that the temperature during the process inside the pre-carbonator was maintained at about 6°C and the pressure reached about 0.08 MPa. During atomization of the C0 ₂ , the latter was converted to dry ice by expansion, having cooled to around -76°C. The introduction lasted about 1 minute.

After this operation, the discharge valve of the pre- carbonator was opened and the pre-carbonated water passed into the mixer where it was mixed with a syrup consisting of vegetable extracts and sugar, with the usual composition of a cola syrup.

The mixture passed immediately to the post-carbonator where a classical carbonation was carried out at 0.6 MPa. The final product contained 6 g/L of C0 ₂ .

In tests carried out at the Centre de Recherches Claude Delorme (Air Liquide, Paris) , it was shown that both in the glass as well as in sampling (tasting) its performance was clearly superior to that obtained with a classical carbonation.

It was shown in particular that the product from a bottle open for several days maintains a sufficient quantity of dissolved C0 .

The cola soft drink obtained was packed in PET bottles and kept under perfect conditions for a storage period of 1 year.

After this period, the organoleptic qualities were evaluated by tasters and compared with a cola soft drink obtained using the conventional process, and it was shown that these qualities were maintained to a much higher degree.

Example 3: Preparation of lime and lemon soft drink

100 L of water and 80 g of liquid C0 ₂ were introduced simultaneously into a pre-carbonator of a two-stage carbonation system, similar to that shown in Figure 2, previously filled with gaseous C0 ₂ and cooled to about 6°C, via the respective valves and in such a manner that the jets of the atomized fluids intersected inside the apparatus, proceeding in a manner identical to that indicated in Example

2. The pressure inside the chamber reached approximately 0.15 MPa during this operation.

After this operation, the pre-carbonated water passed as in Example 2 to the mixer, being mixed therein with a syrup consisting of an extract of lime-lemon and sugar.

Immediately afterwards, a conventional post-carbonation was carried out as in Example 2, a lime-lemon carbonated beverage being obtained with excellent organoleptic proper¬ ties and optimal fixation of C0 in the liquid, as evaluated by tasting and conservation tests.