EP2587943A1

EP2587943A1 - Method and equipment for producing oxidation-sensitive liquids implementing the injection of hydrogen immediately prior to pasteurization

Info

Publication number: EP2587943A1
Application number: EP11727193.2A
Authority: EP
Inventors: Philippe Campo; Dominique Ibarra
Original assignee: Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2010-07-01
Filing date: 2011-06-24
Publication date: 2013-05-08
Also published as: FR2962010B1; FR2962010A1; WO2012000903A1; US20130108751A1; AU2011273610B2; AU2011273610A1; BR112012033707A2; CN102958390A

Abstract

The invention relates to a method for producing a liquid or semi-liquid product that is sensitive to oxidation, for example beverages, wherein the production method includes a step of deoxygenating an intermediate medium involved in the production of either the liquid or the semi-liquid, and a heating step, for example pasteurization, after the deoxygenation step, characterized in that the method involves injecting a hydrogenated gaseous mixture into the liquid or semi-liquid between the deoxygenation step and the heating step.

Description

PROCESS AND PLANT FOR PRODUCING OXIDATION-SENSITIVE LIQUIDS USING INJECTION

The present invention relates to the field of processes for the production of liquid or semi-liquid products which are sensitive to oxidation and whose manufacturing process has no effect, for example pasteurization, c. This is the case, for example, with certain food products such as still or sparkling drinks, fruit juices, flavored waters, compotes or jams, or dairy products, particularly certain cheeses, etc.

Let us consider in the following the example of beverages, these drinks indeed see their quality deteriorate, firstly during the manufacturing process (especially during a pasteurization stage), and secondly during their subsequent storage. This phenomenon can alter both the sensory quality (taste, smell, color ...) and the nutritional quality (vitamin content in particular) of these products. The life of the products is obviously affected.

By way of illustration, it is known from numerous studies that citrus flavored drinks, and in particular lemon drinks, are very sensitive to oxidation. Other studies have focused on the effect of pasteurization on orange juice and have shown that the loss of limonene, which often accounts for more than 93% of all flavor compounds in the concentrate used raises to almost 16%. It is partly due to the oxidation of this molecule which leads to the increase of limonene oxides: α-terpineol, nerol and geraniol in particular.

On the other hand, among the dyes used in this sector, β-carotene (yellow-orange, E 160a) and paprika extracts (orange-red, E 160c) are also sensitive to oxidation. In the same way beet red (pink-red, E 162) has a limited stability in the presence of oxygen, hence the difficulties encountered by manufacturers to preserve their red fruit drinks, whose color gradually turns brown when their storage at room temperature. This problem is all the more marked when the manufacturer wants, to meet consumer expectations, not to use preservatives. It is important to note that color is the first product characteristic that the consumer sees on the shelf, so it is an important purchasing factor, sometimes even decisive.

In the case of the presence of oxygen, the oxidation can be rapid in the treatment stages where the product is heated, in particular in a possible pasteurization step. The oxidation is obviously slower when the product is at ambient temperature, in particular during its storage period. Factors may, however, contribute to faster degradation / oxidation during this period, particularly exposure of the product to light, diffusion of oxygen through the package, etc.

Oxidation is frequently attributed to the oxygen permeability of plastic packaging. In fact, whatever the quality of the inerting during bottling (quantity of residual oxygen in the head space of the packaging), the residual dissolved oxygen contained in the product during its packaging and the diffusion over time of the oxygen through the packaging, makes it difficult or impossible for some containers to completely eliminate the risk of oxidation over time. However, it is possible to delay at least partially the oxidation. Indeed, a preponderant part of the oxidation is based on radical reactions, radicals produced among others by dissolved oxygen, light and compounds initiators and organic propagators.

Limiting these last compounds helps to reduce oxidation, especially during the storage period of the product. It is therefore essential that the oxidation process can not begin at the production stage of the beverage or any of its ingredients.

The literature has noted that the mechanisms of oxidation are in 3 distinct phases:

1 - The initiation: The initial reaction mechanism consists of the formation of a free radical by tearing off a hydrogen atom.

RH → R ^* + H ^*

The oxidation is first very slow because of the low rate of initiation. Indeed, the departure of the hydrogen atom is unlikely because of the high activation energy of the reaction. It is however facilitated by heating, light or metal ions.

2- The propagation;

In the presence of oxygen, the free radical R ^* reacts to give rise to the formation of a peroxyl radical ROO ^* . The latter stabilizes its structure by tearing out one hydrogen atom on another molecule R'H. The free radical R "thus formed is highly reactive and can continue the reaction following the same principle (loop reactions).

R ^* + O ₂ → ROO ^*

ROO ^* + R'H → ROOH + R "

3- Termination

When the concentration of free radicals becomes sufficiently important, the latter combine to stop the propagation chain.

R ^* + R'OO ^* → ROOR '

R '+ R "→ RR'

2 ROO ^* → ROOR + O ₂

So-called "antioxidant" (AH2) molecules, that is to say having a redox potential lower than that of free radicals, can also stop the oxidation. Thus, for example, amines, phenols, sulfur derivatives and certain polycondensed aromatic hydrocarbons are weak inhibitors of oxidation reactions.

R ^* + AH ₂ → RH + AH ^*

ROO + AH ₂ → ROOH + AH ^* It is understandable then that this industrial sector is in constant demand of processes making it possible to limit the oxidation of these products, to lengthen their Optimum Use Limit Date and thus to reduce the costs for the industrialist.

And it is also understood that one of the means of fight identified against the oxidation of sensitive liquids is to delay or limit the initiation phase. For this, it is necessary to act before the heating step, in order to reduce the production of the free radicals R ^* and ROO ^* , which are the precursors or initiators of the oxidative chain reactions which will deteriorate the product during the propagation phase.

This industry has proposed various technical solutions, which include the following approaches: I) Use of antioxidants

The main antioxidants used in food products are:

ascorbic acid and its sodium and calcium salts as well as ascorbyl palmitate and ascorbyl stearate esters (E 300 to E 304N),

tocopherols (E 306 to E 309),

esters of gallic acid: propyl, octyl and dodecyl gallate

(E 310 to E 312),

buthylhydroxyanisol (BHA, E 320),

buthylhydroxytoluene (BHT, E 321).

The use of antioxidants is, however, subject to regulatory constraints (restriction of use, dose to be respected). For example, in fruit juices and nectars, only the following antioxidants are allowed: E 300 and E 301 according to Directive 95/2 / EC of the Parliament and the Council. BHA and BHT are used for example as antioxidants in flavor solutions used in the composition of beverages.

The use of additives has several disadvantages, including the legal requirement to include the list on the labeling of the finished product. In addition, the additives in general, and therefore the antioxidants, are very often, by their denomination (E XXX), assimilated to "chemicals", "not natural", by consumers. Moreover, they not only convey a negative image, but they are not always sensorially neutral.

Some additives can cause physiological disorders (BHA and BHT in particular) and it is then necessary to adapt their dosage to respect the Admissible Daily Ratios defined in the legislation. This constraint can limit their effectiveness.

In addition, ascorbic acid, erythorbic acid and ascorbyl palmitate are not very stable to heat while gallates are heat-sensitive.

Finally, the mechanisms of action of antioxidants have an effectiveness which remains however limited because they are very easily oxidizable molecules (weak reducing power).

J) Deoxygenation: vacuum or gas (degassing)

Deoxygenation is a way to fight against oxidation phenomena and thus increase the shelf life of a product. This deoxygenation (or degassing) step can be carried out either by a process based on a total or partial evacuation of the product, or by a gas entrainment of the dissolved oxygen by injection of an inert gas, commonly known as a process. called "stripping".

By way of example, mention may be made of US Pat. No. 2,151,644, which proposes a method for deaerating a liquid food product by continuously circulating a liquid in the form of a film in a vacuum chamber. Similarly, WO2005 / 004643 proposed a continuous deaeration of lemon juice cold (~ 0 ° C to 10 ° C) and under vacuum.

WO2006 / 039674 discloses the use of porous type injectors to introduce nitrogen in the form of small bubbles at different points of the production line to reduce the amount of dissolved oxygen in the product. lemon juice. Deoxygenation technologies, whether they use vacuum or a neutral gas such as nitrogen, simply disperse the oxygen present in the liquid. Thus, they make it possible, for example, to limit the aerobic degradation pathway of vitamin C and the appearance of browning in an orange juice. However, there is still residual oxygen, or possibly oxidants comprising combined oxygen, especially nitrates and sulphates, capable of reacting to oxidize the sensitive molecules. In this, this solution is not completely satisfactory. K) Deoxygenation with a gaseous mixture containing hydrogen

The Applicant has proposed in document FR-2 81 1 292 a process for packaging perishable products including in particular the possibility of introducing into a liquid product a protective gas comprising a certain quantity of hydrogen, the balance being formed by one or more conditioning gas. It will be understood that this prior method is therefore only concerned with the conditioning stage, that is to say after the pasteurization stage. It therefore protects the liquid during storage, but it does not protect it from oxidation that is initiated during pasteurization.

Other studies have investigated at laboratory scale (150 mL) the impact of a nitrogen or nitrogen-hydrogen bubbling (96% N ₂ , 4% H ₂ ) before pasteurization on the microbiological quality, the color and ascorbic acid content of an orange juice, and have shown that deoxygenation, with nitrogen or nitrogen-hydrogen, results in a loss of effectiveness of pasteurization (less of killed microorganisms) compared to the same process without prior deoxygenation. Moreover, after seven weeks of storage, the authors find that deoxygenating before pasteurization improved the stability of ascorbic acid and that of color compared to the absence of prior deoxygenation. However, they do not observe a significant difference between nitrogen deoxygenation and nitrogen-hydrogen deoxygenation. At the end of this study, the authors therefore recommend introducing the gas into the liquid just after pasteurization so as to maximize the destruction of microorganisms while stabilizing the product during storage. As will be seen in more detail in the following, the present invention proposes a new process for manufacturing a liquid or semi-liquid product such as those referred to above, undergoing a heating step, in particular a pasteurization step, to limit the formation of compounds that can act as initiators and / or propagators radicaux in oxidation reactions during the storage period of products, and thus to increase their shelf life.

The new approach of the invention is based on the fact that it is not content, as the prior art proposed, to deoxygenate the product before pasteurization, it proposes to combine a deoxygenation step, whatever the process used (vacuum, sweep with an inert gas, using a gas mixture containing hydrogen ...), the injection of a hydrogenated gas mixture between step deoxygenation and the heating step, preferably just before the heating step, and as will be seen this amount can be minimal. This injection makes it possible to use the reducing character of the hydrogen in an optimum manner, because under very favorable conditions since the hydrogenogen is injected immediately thereafter (during heating) at a temperature greater than room temperature. . The present invention thus relates to a process for producing a liquid or semi-liquid product sensitive to oxidation, a production process that includes a step of deoxygenation of an intermediate medium involved in the manufacture or liquid or semi-liquid liquid itself, and which comprises a heating step, for example a pasteurization, subsequent to the deoxygenation step, characterized in that one proceeds, between the deoxygenation step and the heating step, to the injection into the liquid or semi-liquid of a hydrogenated gaseous mixture. It will be understood, in most cases deoxygenation is carried out on the liquid or semi-liquid medium itself (the pure juice, or even the already flavored water, compote ...) but it can also the fact that the deoxygenation step takes place on an intermediate mill intervening in the production. For example, in the case of a fruit juice based concentrate, it is possible to deoxygenate the water alone first, then add the concentrate, before performing the gas injection according to the invention. According to advantageous embodiments of the invention, the latter may adopt one or more of the following technical characteristics:

the hydrogenated gaseous mixture is pure hydrogen;

the hydrogenated gaseous mixture is a mixture of nitrogen and hydrogen, the hydrogen content of which is between 1% and 100%, but preferably between 50% and 100%;

- The deoxygenation stage of the intermediate medium or liquid or semi-liquid is performed by a total or partial vacuum of the intermediate medium or the liquid or semi-liquid considered;

the deoxygenation step is performed by injecting into the intermediate medium or the liquid or semi-liquid considered an inert gas or a gaseous mixture comprising a reducing gas such as hydrogen;

the injection of the hydrogenated water between the deoxygenation stage and the heating step is carried out just before the heating step, typically taking into account the time required for the transfer of hydrogen in the liquid phase, and therefore preferably from 5s to 30s before the heating step.

The present invention also relates to an installation for producing a liquid or semi-liquid product that is sensitive to oxidation, which installation comprises a deoxygenation device of an intermediate medium involved in the manufacture of liquid or semi-liquid itself, as well as a device for heating this liquid or semi-liquid, located downstream of the deoxygenation device, characterized in that it comprises a device for injecting into the liquid or semi-liquid a hydrogenated gaseous mixture, located between the deoxygenation device and the heating device.

According to one of the embodiments of the invention, the device for injecting the hydrogenated gas may be the same as the deoxygenation device when the latter is produced by injection of an inert or non-inert gas such as a hydrogenated gas. (loop operation).

Other features and advantages of the present invention will appear more clearly in the following description, given by way of illustration but not by way of limitation, with reference to the appended figures in which:

FIG. 1 is a simplified diagram for visualizing the locations in which the invention operates;

FIG. 2 is a partial diagrammatic representation of a manufacturing and bottling facility according to the invention, which made it possible to produce implementation examples;

- Figure 3 is a variant of the installation of Figure 2, not implementing cooling after pasteurization, and combining in a single injection injections A and B of Figure 2.

The following steps are recognized in FIG.

step a) of "liquid preparation", which is a liquid reconstitution step, for example the production of the water mixture, juice concentrate, pulp, or the production of a mixture of water and various ingredients of aromatization in the case of a flavored water, but it is understood that this preparation step may be non-existent in some cases or reduced to a minimum by the fact that the liquid is already ready (for example what is calls a "pure juice"); step b) which is a deoxygenation step, for example by injecting an inert gas into the liquid. It should be noted that in order to carry out deoxygenation, the injection of nitrogen or of another gas alone is not enough, as is known, the liquid will have to pass, further down the production line, in an equipment which allows the oxygen-laden gas to come out of the liquid and the line.

It has been said that this deoxygenation can be carried out by vacuum, but a gas sweep will be preferred, on the one hand to avoid the subsequent "coatings" of the package, and on the other hand to reduce the loss of aroma at this stage. Not to mention the fact that the gaseous method is less energy consuming and requires less investment in equipment.

An addition of ingredients can possibly take place after this deoxygenation. Thus, for example, in the case of a fruit juice based on concentrate, it is possible to deoxygenate the water and then add the concentrate after step b) and before step (c). In this case we can realign the sequence b) then c) (then b) again if necessary) then d)

This introduction of an inert gas into the liquid makes it possible to move the oxygen from the liquid phase to the gas phase. This deoxygenation can be done in tanks, whose headspace is inert, or online according to equipment well known to those skilled in the art.

step c) which consists in injecting into the liquid a hydrogenated mixture, here pure hydrogen;

step d) of pasteurization;

- Very often, there is a cooling step (e) of the product downstream of the heating step and before the conditioning of the produ it, but this cooling is only optional;

the liquid resulting from the pasteurization (or cooling) being then sent downstream of the line (f), that is to say towards the following stages of the production of this liquid, for example a setting bottles of the drink. As is understood, it is highly preferable, downstream of the deoxygenation step (b), to ensure that all the vessels and other equipment in which the liquid passes are carefully inerted, including the equipment used. downstream of the pasteurization, and in particular the final conditioning (f).

As noted above, the amount of hydrogen added just before pasteurization can be tiny.

When we consider the curve (well indexed in the literature) which represents the solubility of hydrogen in water at atmospheric pressure as a function of temperature, we observe, for example, that this solubility is of the order of 1, 6 mg / l at 20 ° C under about 1 bar. Still referring to the curves of the literature at different pressures it is of the order of 4.8 mg / l at 20 ° C under about 3 bar.

FIG. 2 is a partial schematic representation of a manufacturing and bottling facility for the implementation of the invention.

This beverage production line allows the bottling of an hourly flow rate of 10 m ³ / h of liquid.

Of course, in this figure 2 we find the essential elements of the schematic representation of FIG. 1, and in particular:

the vat for the preparation of the beverage or the storage of a pure juice for example, this vat here undergoing two injections of nitrogen: the injection A in the liquid, intended to pass the oxygen from the liquid phase to the gas phase, and the injection B, in the top of the tank, which serves to inerter the tank (these two injections can if necessary be combined, see Figure 3);

- the injection in line (C) in the liquid, just upstream of the pasteurization device, a flow rate of 0.18 Nm ² / h of pure hydrogen, this injection will be realized for example by means of a porous type injector, a static mixer, or Venturi, or any other equivalent equipment.

The injector is thus positioned on the line upstream of the heat exchanger of the pasteurization, preferably leaving a contact time after the injection of between 5 and 30s.

The quantity of hydrogen injected will preferably be between the saturation value at room temperature under one atmosphere and the saturation value under the same temperature conditions at the pressure of the beverage line. For the implementation example of FIG. 2, which is a production line at 3 bar, the quantity injected is preferably between 16 and 48 g / h of hydrogen, ie between 0.18 and 0.54 Nm. ³ / h of pure hydrogen.

- Downstream of the pasteurization equipment and after cooling of the product is positioned an inert buffer tank (injection D), this tank can be inerted in static mode (without renewal of the gaseous sky), or in scan mode (renewed, which is preferred). In the latter case, and in order to eliminate any excessively high moisture consumption in the atmosphere, it is preferable to sweep the head space of the buffer tank with an inert gas, for example example of the nitrogen at a minimum rate so that the concentration of hydrogen in the gas phase is in all circumstances less than 4%, thereby eliminating any known risk.

For the exemplary implementation of this FIG. 2, a flow rate of the sky was swept by an inert gas at a minimum flow rate of QN ₂ = 0.18 / 0.04 = 4.5 N m ³ / h, or about 0.5 Nm ³ of nitrogen per cubic meter of beverage produced.

The measurements made on the fruit juices thus produced, after all the steps and after three days of storage, show a residual hydrogen level equal to 25% of the saturation in the glass bottles at 20 ° C., and equal to 4% in PET bottles. It is then conceivable that the advantage of injecting hydrogen or a hydrogenated mixture into the location where it is envisaged according to the invention since thus:

it intervenes in a location where the liquid is already deoxygenated; - It does not intervene too early in the process, the risk that the hydrogen is removed at the time of degassing and with the adverse consequence that the hydrogen would no longer be present at the time of heating;

it does not intervene too late in the process, for example after pasteurization, since, and it is the whole inventive step of the present invention, it is desired that the dissolved hydrogen be present during this pasteurization step to avoid the formation of oxidation precursors during heating.

Other advantages of the method of the invention over prior solutions can be summarized in the following:

It adapts easily to the existing line.

It does not represent a significant investment.

He does not just hunt for oxygen.

It does not present any sensory or legal constraints or impact on human physiology.

It benefits from the highly reducing power of hydrogen (compared to the antioxidants usually used), without having to add additives of mineral and / or organic types.

It does not increase the labeling (list of ingredients).

It does not cause additional flavor losses.

Claims

claims

1. A process for producing a liquid or semi-liquid product sensitive to oxidation, a production process which comprises a step of deoxygenation of an intermediate medium involved in the manufacture or the liquid or semiliquid same, and which comprises a step of heating, for example a pasteurization, subsequent to the deoxygenation step, characterized in that one proceeds, between the step of deoxygenation and the step of heating, with the injection into the liquid or semi-liquid of a hydrogenated gaseous mixture.

2. Process for producing a liquid or semi-liquid product sensitive to oxidation according to claim 1, characterized in that the hydrogenated gaseous mixture is pure hydrogen.

3. Process for producing a liquid or semi-liquid product sensitive to oxidation according to claim 1, characterized in that the hydrogenated gaseous mixture is a mixture of nitrogen and hydrogen, the hydrogen content of which is between 1% and 100%, preferably between 50% and 100%.

4. Process for producing an oxidation-sensitive liquid or semiliquid product according to one of Claims 1 to 3, characterized in that the deoxygenation step is carried out by total evacuation. or partial.

5. Process for producing an oxidation-sensitive liquid or semiliquid product according to one of Claims 1 to 3, characterized in that the deoxygenation step is carried out by injection of a inert gas or a gaseous mixture comprising a reducing gas such as hydrogen.

6. A process for producing an oxidation-sensitive liquid or semiliquid product according to one of claims 1 to 5, characterized in that the injection of the hydrogenated gaseous mixture between the step of deoxygenation and the heating step is carried out j uste before the heating step, preferably from 5s to 30s before the heating step.

7. Installation for producing a liquid or semi-liquid product that is sensitive to oxidation, an installation that includes a device for deoxygenating an intermediate medium involved in manufacturing, or liquid or semi-liquid itself, as well as a liquid or semi-liquid heating device, located downstream of the deoxygenation device, characterized in that it comprises a device for injecting into the liquid or semi-liquid a hydrogenated gaseous mixture, located between the deoxygenation ispositif and the heater.