HK1201561B - Material and packaging for the conservation of yeast - Google Patents

Description

Field of the Invention

The present invention relates to the field of packaging and the preservation of liquid or semi-liquid products that produce gas, preferably carbon dioxide (CO2), and more particularly to packaging for the packaging of liquid or semi-liquid products containing yeasts or leaven.

Invention Context

Aquatic suspended yeast, when stored under favorable conditions, offers undeniable advantages compared to solid yeasts, known as compressed or dried yeasts, especially due to its simplified handling, pre-dosing, and excellent performance, which makes it a highly appreciated product among bakery professionals. However, aquatic suspended yeast is a very sensitive product regarding its storage conditions, particularly its environment (temperature, pH, CO2/O2 content, etc.), and is especially prone to contamination. Therefore, it is a difficult product to package and requires hygienic storage conditions that ensure the maintenance of its microbiological quality,Regarding its performance, particularly in terms of fermentative power and its organoleptic properties. Furthermore, the activity and reactivity of a yeast, while ensuring good performance during its use, represent a specific drawback for the storage of such a product. For proper storage, it is therefore advisable in practice to keep the yeast in an aqueous suspension at a low temperature, around 4°C, to provide specific means for degassing, especially for releasing gases resulting from the yeast's respiratory metabolism, particularly carbon dioxide, while limiting other gas exchanges (oxygen from ambient air), especially to prevent the development of contaminations.

Several packaging solutions for aqueous yeast suspensions have been proposed. One of these solutions consists of packaging the liquid yeast in a Bag-in-Box system. The principle of the Bag-in-Box is to place, in a box usually made of cardboard (see, for example, U.S. Patent No. US 6,223,981), a flexible bag equipped with one or more filling and/or emptying openings, called spouts (see, for example, U.S. Patent No. US 4,863,770). Each spout can be equipped with a screw thread or rings, allowing respectively to screw or snap on a cap. The resulting Bag-in-Box can be stored for several weeks at a temperature between 0 and 6°C and a relative humidity between 50 and 100%.The user can retrieve a given amount of suspended yeast that has been preserved by opening the cap and using a valve or tap fitted to a base. In the case of a valve installation, the user turns the Bag-in-Box completely upside down and places it in an adapted refrigerated dispenser (see, for example, the system described by the present applicant in international patent application WO 2004/048253). In the case of a tap installation, the Bag-in-Box is placed horizontally in a refrigerator or cold room.

To prevent the flexible bag contained in the Bag-in-Box from swelling due to the carbon dioxide gas produced by the yeast, vent holes are provided as specific means for degassing (see, for example, European patent EP 0 792 930-B1 and international application WO 2004/048253 filed by the Applicant). Moreover, the flexible bag is sized to leave a sufficient headspace within the Bag-in-Box, allowing the gas to be stored until a sufficient pressure is reached to enable gas evacuation through the degassing cap. However, this degassing system is not entirely satisfactory.In particular, when the stored liquid yeast is an unstabilized yeast that produces larger amounts of CO2 than stabilized yeast. Indeed, the swelling of the flexible pouch, which can cause deformation of the cardboard, giving it a bulging appearance, not only causes stability issues with the Bag-in-Box but can also prevent its insertion into the refrigerated dispenser. In some cases, the swelling may even lead to the cardboard rupturing. Moreover, if the Bag-in-Box is under pressure, its opening by the user may result in a geyser of product. Finally, during the transportation or handling of a Bag-in-Box,If yeast comes into contact with the degassing plug, it can become temporarily or permanently clogged.

The present Applicant's EP 2 019 051 application describes a liquid product packaging containing yeast, comprising a permeable material having an S/M ratio (exchange surface S of the material expressed in cm² relative to the mass M of the liquid product containing yeast expressed in grams), and oxygen (O2) and carbon dioxide (CO2) permeability coefficients determined, among other things, to prevent product swelling and to prevent the penetration of contaminants. However, such an S/M ratio does not allow for great flexibility in choosing the shape and dimensions of the pouch.

Therefore, there is a need for packaging suitable for the storage and preservation of liquid products containing yeast, and which allow for better degassing of the CO2 produced by the respiratory metabolism of the yeast.

Summary of the Invention

In general, the present invention is based on the use of a multilayer plastic film with a B-A-B' structure, having specific properties of composition, thickness, and gas permeability, to form the inner part of the flexible pouch of a Bag-in-Box system. Unlike existing degassing systems, the degassing achieved by using a film according to the present invention is constant over time and uniform across the entire surface of the pouch. It therefore prevents the inflation of the flexible pouch and all potential problems associated with this inflation.

More specifically, in a first aspect, the present invention relates to a three-layer plastic film as defined in claim 1, as packaging for a liquid or semi-liquid ingredient that produces gas, preferably carbon dioxide (CO2).

In certain manufacturing methods, the gas permeability of the film, measured according to ISO 15105-2:2003 Annex B, is greater than or equal to 90 1/m²·24 h at ΔP = 1 bar.

Layer A consists of a vinyl ethylene acetate (EVA) with a high vinyl acetate content, and each of the layers B and B' comprises an EVA having a lower vinyl acetate content than the EVA in layer A. In certain embodiments, the vinyl acetate content of the EVA included in layer B is the same as the vinyl acetate content of the EVA included in layer B'. In other embodiments, these contents are different. In some embodiments, the high-vinyl acetate EVA includes, by weight percentage, between 18% and 42% vinyl acetate.

In a second aspect, the present invention relates to a plastic composite material comprising two plastic films, characterized in that the first plastic film is a trilayer film of the invention, and the second plastic film is uniformly perforated or has a carbon dioxide permeability equal to or higher than that of the first plastic film.

In a particular embodiment of the invention, the second plastic film is composed of oriented polyamide (OPA) and polyethylene (PE) or polyethylene terephthalate (PET) and polyethylene (PE).

In a third aspect, the present invention relates to a packaging comprising a reservoir/container made of the plastic material of the invention, characterized in that the first plastic film of the material defines the internal volume of the reservoir/container.

In certain embodiments of the invention, the tank/container is in the form of a bag with a total internal volume ranging from 1 L to 1000 L, preferably from 10 L to 200 L, and more preferably from 10 L to 50 L.

The package may include at least one base and a cap.

In certain embodiments of the invention, the packaging is in the form of a Bag-in-Box and further includes a cardboard box having an opening. In some embodiments, the base of the bag is screwed or clipped into the opening of the cardboard. In other embodiments, the base of the bag is not attached to the opening of the cardboard.

In a fourth aspect, the present invention relates to the use of the plastic material of the invention for the manufacture of a tank/container intended to receive a liquid or semi-liquid ingredient that produces gas, preferably CO2.

In a fifth aspect, the present invention relates to the use of the invention's packaging for the storage and use of a liquid or semi-liquid ingredient that produces gas, preferably carbon dioxide (CO2), characterized in that the packaging allows the release of the produced gas.

In a sixth aspect, the present invention relates to a method for preserving and using a liquid or semi-liquid ingredient that produces gas, preferably carbon dioxide (CO2), comprising the following steps: packaging the gas-producing ingredient in the packaging of the invention, storing it at a temperature between 0 and 6°C and at a relative humidity between 50% and 100% of the packaged ingredient until its use, and using the liquid or semi-liquid gas-producing ingredient.

The present invention is as defined in claims 1 to 15.

In some preferred modes of realization of the invention, the liquid or semi-liquid gas-producing ingredient includes a leaven or yeast, particularly liquid yeast or yeast cream.

A more detailed description of certain preferred embodiments of the invention is given below.

Detailed Description of the Invention

As mentioned above, the present invention is based on the use of a multi-layer plastic film, optionally reinforced by a second perforated plastic film, as packaging for a liquid or semi-liquid ingredient that produces gas, particularly carbon dioxide.

I - Multi-layer Plastic Film

A multi-layer plastic film according to the invention is characterized by the following properties: the film has a B-A-B' type structure; the layers comprising the film are extruded to a total thickness between 20 and 50 microns, preferably between 25 and 35 microns, and more preferably between 27 and 32 microns; the film's permeability to carbon dioxide is equal to or greater than 60 1/m²·24 h at delta P = 1 bar, and the film is weakly impermeable to oxygen (O₂) and/or air and exhibits an oxygen permeability equal to or less than 30 1/m²·24 h at delta P = 1 bar.

The three-layer plastic film according to the invention is generally liquid-proof and preferably vapor-proof. Moreover, since this plastic film is intended to contain a liquid or semi-liquid product containing yeast, it is preferably composed of components suitable for regulations regarding materials in contact with food products.

In the trilayer structure B-A-B', the compositions of layers B and B' can be exactly the same at all points. Alternatively, the compositions of layers B and B' can be different.

Layer A consists of a polyethylene-vinyl acetate (EVA) with a high vinyl acetate content, and each of the layers B and B' comprises a polyethylene-vinyl acetate (EVA) with a lower vinyl acetate content. Here, "EVA with a high vinyl acetate content" refers to an EVA containing between 18% and 42% vinyl acetate, the percentages being weight percentages. By "EVA with a lower vinyl acetate content," it is meant an EVA that contains a lower percentage of vinyl acetate than the EVA forming layer A.Layers B and B' can be composed of the same ethylene-vinyl acetate (thereby containing the same vinyl acetate content) or of EVA copolymers with different vinyl acetate contents. In all cases, these vinyl acetate contents must be lower than that of the EVA forming layer A. A layer in the B-A-B' structure can have a constant weight percentage of vinyl acetate throughout the entire layer. Alternatively, a layer in the B-A-B' structure can have a composition gradient, with the weight percentage of vinyl acetate, for example, increasing or decreasing in a given direction within the layer.

The preparation of a multi-layer plastic film according to the invention can be carried out using any appropriate method known in the art. In certain preferred embodiments, the three-layer plastic film is prepared by co-lamination or by co-extrusion. Co-extrusion can be performed using a flat die extrusion technique (called "cast") or an extrusion-blown technique. Those skilled in the art will know how to select the most suitable technique depending on the composition of the multi-layer plastic film and/or the dimensions of the film to be prepared. Those skilled in the art will also know how to determine the optimal operating conditions of temperature, pressure, and relative humidity for implementing the selected technique.

Surprisingly, the present Applicant has found that, in order to allow for an effective daily evacuation of CO2 while enabling the production of flexible pockets on commonly used formers, the three-layer plastic film must have a thickness ranging from 20 to 50 microns, preferably from 25 to 35 microns, and more preferably from 27 to 32 microns.

The utility of the multilayer plastic film according to the invention in packaging liquid or semi-liquid products that produce gas, and in particular liquid or semi-liquid products containing yeast, results from its gas permeability properties. More specifically, a film according to the invention has a CO2 permeability equal to or greater than 80 1/m²·24 h at delta P = 1 bar, preferably equal to or greater than 90 1/m²·24 h at delta P = 1 bar, and is weakly impermeable to oxygen and/or air. By "impermeable to oxygen and/or air," it is meant a film that has an oxygen (O2) permeability lower than or equal to 30 1/m²·24 h at delta P = 1 bar.

According to the invention, the CO2 and O2 permeabilities, also called permeability coefficients (PC), are defined as the respective transmission coefficients of carbon dioxide (or carbon gas) and oxygen, expressed in cm³ per m² per 24 hours per bar (cm³/m²·24h·bar or 1/m²·24h·bar), and measured according to ISO 15105-2:2003 Annex B by a gas chromatography method with a catharometric detection, using an injection valve and sampling loop. Prior to measurement, the material is conditioned for 48 hours at 23°C and a gas humidity of 0% HR. The permeability coefficient measurement is performed at a temperature of 23°C, with a gas humidity of 0% HR. The external surface of the material is exposed to test gases, and measurements are carried out on three specimens of 50 cm² each. The test gas consists of a mixture of 50% oxygen and 50% carbon dioxide. Chromatographic detection is performed using a Porapak® Q detector, with a detector temperature of 140°C, a filament current of 200 mA, after calibrating the chromatograph with standard gases having known concentrations of oxygen and carbon dioxide.

For more accurate measurements of low permeability coefficients CP to oxygen (i.e., less than 5000/cm³·m²·24h·bar), the measurement is carried out according to ISO 15105-2:2003 Annex A and ASTM D 3985-05 using a Systech 8000 device. Prior to measurement, the material is conditioned for 48 hours at 23°C and a gas humidity of 0% HR. The permeability coefficient is measured at a temperature of 23°C, with a gas humidity of 0% HR. The external surface of the material is exposed to the test gases, and measurements are taken with 21% oxygen on three samples of 0.5 dm². The stabilization time is 24 hours.

If the detection threshold of the device is reached, it is possible to reduce the oxygen content in the test gases and/or on the measured surface, thereby returning to detection conditions. It is then sufficient to weight the obtained result by the applied reduction in oxygen content and/or by the applied reduction in surface area.

For the measurement of the CO₂ permeability coefficient alone, it is also possible to apply the flame ionization detection method on a gas chromatograph with an injection valve and sampling loop according to ISO 15 105-2:2003, Annex B.

II - Plastic Material

A plastic material according to the invention comprises two plastic films, the first being a multi-layer plastic film as described above, and the second plastic film being perforated or having a carbon dioxide permeability equal to or higher than that of the first plastic film. The second plastic film has two roles: it provides mechanical strength to the resulting flexible pouch, and its permeability or perforations allow the evacuation of gas produced by the yeast, which is evacuated through the permeability of the first plastic film.

Surprisingly, the present Applicant has found that when the second plastic film did not have a CO2 permeability equal to or higher than that of the first plastic film, only a perforation distributed over the entire surface of the second plastic film allowed for an efficient evacuation of the gas produced by the yeasts. It was also observed that, in order to allow for good gas evacuation from the yeasts stored in the flexible pouches, the perforation density had to be high. Thus, the second plastic film must contain at least 1,000 perforations/m², preferably at least 5,000 perforations/m², and more preferably about 7,000 perforations/m².

As mentioned above, the second plastic film, which is intended to be located outside the flexible pocket designed to contain the yeast, provides mechanical strength to this pocket. Therefore, the plastic film components must be selected accordingly. Here, "mechanical resistance" refers to any property or combination of properties such as hardness, rigidity, flexibility, elasticity, etc., which increases the durability of the flexible pocket. For example, mechanical resistance can be resistance to drops and/or shocks. Indeed, it is desirable that the containers holding liquid or semi-liquid products remain leak-proof upon impact, considering that occasional drops are almost inevitable during the transportation of industrial products.

In certain preferred embodiments, the component(s) of the second plastic film are selected from polyethylene (PE), high-density polyethylene (HDPE), low-density polyethylene (abbreviation in English: LDPE), linear low-density polyethylene (abbreviation in English: LLDPE), polycarbonate, polyester, polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polypropylene (PP), polyamide (PA), oriented polyamide (OPA), and their mixtures and/or combinations. In particular, the second plastic film can advantageously be composed of oriented polyamide (OPA) and polyethylene (PE) or of polyethylene terephthalate (PET) and polyethylene (PE). The second plastic film may, for example, be obtained by extrusion, co-extrusion or lamination.

The preparation of the plastic material according to the invention can be carried out by any method known in the art, provided that in the resulting material, each of the two plastic films can fulfill its role or roles (i.e., in particular, gas permeability, especially for carbon dioxide, and low permeability to oxygen and/or air for the first plastic film, mechanical strength and gas venting through perforations or via CO2 permeability for the second plastic film). In some preferred embodiments, the first and second plastic films are assembled only at the time of manufacturing the flexible pouch, for example by welding the two films on all four sides of the pouch. Another example is the "pouch-in-pouch" system, in which the pouches are fixed to each other, either on all four sides or only at the base.

III - Packagings

A packaging according to the invention generally includes a reservoir or container made of a plastic material as described above, in which the first plastic film defines the internal volume of the reservoir that is intended to contain the liquid or semi-liquid product generating gas. The reservoir or container can be of any shape (cylindrical, cubic, rectangular, flat, etc.) and/or any size. In some preferred embodiments, the reservoir in the container is a flexible bag or pouch, relatively flat, especially a flexible bag or pouch intended to be used in a Bag-in-Box system.

According to certain embodiments, a pouch according to the invention can contain at least 20 g of liquid or semi-liquid product that produces gas, for example between 25 g and 600 g of product for applications intended for the general consumer market. In such embodiments, the pouch is a flexible bag with a total internal volume ranging between 20 mL and 800 mL, preferably between 20 mL and 500 mL.

According to other embodiments, a bag according to the invention can contain at least 5 kg of liquid or semi-liquid product that generates gas, for example between 10 kg and 1000 kg of product, or between 10 kg and 100 kg of product, or between 10 kg and 50 kg of product for professional applications, for example for professionals in the baking industry such as artisan bakers or industrial bakeries. In such embodiments, the bag is a flexible pouch with a total internal volume ranging from 1 L to 1000 L, for example between 10 L and 200 L, or between 50 L and 500 L, or between 500 L and 1000 L.

A bag according to the invention can contain one or more necks equipped with threads or rings allowing a cap to be screwed on or clipped on. Such necks allow filling and/or emptying of the bag (see, for example, U.S. Patent No. US 4,863,770). Generally, at least one neck will be located at the bottom during use, so that the liquid or semi-liquid product can be drained by gravity or siphoned. The bag or pouch may also be equipped with means facilitating and/or completing the emptying or draining of the bag or pouch. Such means are notably described in DE-A-3 502 455, WO 89/00535, WO 85/0483, WO 90/06888, WO 01/79072 and EP-A-0 138 620.

In certain embodiments, a pouch according to the invention can allow the user to visually determine or estimate the amount of liquid or semi-liquid product contained in the pouch. In particular, the pouch can be transparent or translucent, or can include one or more transparent or translucent parts.

In certain embodiments, the packaging according to the invention is in the form of a Bag-in-Box. In such embodiments, the packaging includes, in addition to the flexible pouch or bag, a supporting wire basket or a rigid (self-supporting) box capable of containing this pouch or bag, as described, for example, in U.S. Patent No. 6,223,981. The rigid box can be a cardboard box.

IV - Use of Packagings Ingredients: Liquid or Semi-Liquid Substances That Produce Gas

A packaging according to the present invention can be used for the preservation of any liquid or semi-liquid ingredient that produces gas, in particular CO2. In some embodiments of the invention, the liquid or semi-liquid gas-producing ingredient comprises yeast or a leaven. In certain specific embodiments of the invention, the ingredient is liquid yeast or a yeast cream.

By "liquid or semi-liquid ingredient containing yeast," it is meant a liquid suspension, typically an aqueous suspension, containing yeast. This is generally fresh yeast or dry yeast that has been reconstituted. According to a preferred embodiment of the present invention, the yeast is fresh yeast. Advantageously, said yeast, when packaged, comprises at least 105 colony-forming units (CFU) of yeast per gram, preferably at least 108 colony-forming units (CFU) of yeast per gram, and advantageously at least 109 colony-forming units (CFU) of yeast per gram.

The liquid ingredient containing yeast has a preferred content of at least 0.03% by weight of dry matter of live yeast cells, preferably at least 0.1%, and even more preferably at least 5% dry matter of yeast.

The packaging according to the invention is particularly suitable for the preservation of yeasts used for their fermentative activity. These include yeasts belonging to the family Saccharomycetaceae (as classified in "The Yeasts, A Taxonomic Study," 4th edition, Kurtzman C.P. and Fell C.W., Elsevier, 1998). Thus, the invention mainly concerns the preservation of baker's yeast, but also relates to the preservation of wine yeasts, distillery yeasts, and/or brewing yeasts, for which problems of preservation in liquid or semi-liquid form arise.

Wine, distillery and/or brewing yeasts are preferably selected from the genus Saccharomyces, particularly S. bayanus, and especially the varieties uvarum, calbergensis, and cerevisiae; the genus Kluyveromyces, particularly K. thermotolerans; the genus Brettanomyces, particularly B. bruxellensis; the genus Torulaspora, particularly T. delbrueckii, either alone or in mixtures.

Bread yeast is preferably a yeast selected from Saccharomyces cerevisiae, Saccharomyces chevalierii, and Saccharomyces boulardii.

The gas-producing ingredient (for example, an ingredient containing yeast) is liquid or semi-liquid, meaning it has a viscosity lower than 20,000 mPa·s (centipoise), preferably lower than or equal to 1,000 mPa·s (centipoise), measured at a temperature of approximately 10°C using a standard viscometer, for example a J.P. Selecta ST2001 viscometer (L1=needle; speed=10 rpm up to a viscosity of 600 mPa·s (centipoise), speed=1.5 rpm above 600 mPa·s (centipoise); on a 500 ml sample. Bread doughs are typically not liquid or semi-liquid products.

The liquid or semi-liquid ingredient containing yeast preferably has a density between 1.01 and 1.25, and more preferably between 1.05 and 1.15.

By liquid or semi-liquid ingredient containing yeast, the present invention particularly refers to yeast cream, preferably baker's yeast, and liquid sourdough.

By yeast cream, preferably bakery yeast, is meant a liquid suspension, typically an aqueous suspension, of live yeast cells, preferably bakery yeast, said suspension having a preferred dry matter content of at least 12% by weight and generally between 12 and 50% by weight (extended definition of yeast cream). Preferably, the liquid or semi-liquid yeast cream meets the strict definition of yeast cream, that is to say, it has a dry matter content between 12 and 25% by weight, and even more preferably between 15 and 22% by weight. However, the present invention is also useful for yeast creams,Preferably bakery-based, with a higher dry matter content, i.e., at least 25% by weight, such as, for example, high-density baker's yeast creams containing one or more osmotic agents, such as, for example, polyhydroxy food compounds and food salts. Such high-density baker's yeast creams, which can particularly have a dry matter content of 25 to 48% by weight, or of 25 to 46% by weight, are known and are, for example, described in WO 91/12315 and WO 03/048342.

By "liquid starter," according to the invention, is meant a liquid suspension, typically an aqueous suspension of living yeast cells, preferably baker's yeast, living lactic acid bacteria cells, and flour. Preferably, the liquid starter has a dry matter content ranging from 12 to 20% by weight, and more preferably from 15 to 17% by weight.

Stable liquid sourdoughs ready for use and suitable for packaging according to the invention are notably those described by the Applicant in European Patent No. EP 0 953 288 B1 and International Application WO 2004/080187.

Advantageously, the liquid sourdough is obtained by implementing a culture medium comprising at least one unleavened cereal flour and water, inoculated with at least one preparation of heterofermentative lactic acid bacteria and at least one yeast preparation. Preferably, the implementation further includes at least one malted cereal flour providing amylases or any equivalent source of amylases and/or an additional inoculation with a preparation of homofermentative lactic acid bacteria. During its packaging, it preferably comprises at least 106 colony-forming units (CFU) of lactic acid bacteria per gram and at least 104 colony-forming units (CFU) of yeast per gram, and even more preferably at least 109 colony-forming units (CFU) of lactic acid bacteria per gram and at least 106 colony-forming units (CFU) of yeast per gram.It has a final stable pH between 4 and 4.3 and a dry matter content between 13 and 20%, and preferably contains 15 to 30 g/kg of lactic acid and 6 to 10 g/kg of acetic acid. The preparation of such a sourdough is described, for example, in European patent number EP 0 953 288-B1.

Another ready-to-use liquid sourdough particularly advantageous according to the present invention comprises a culture medium based on flour containing at least one cereal flour and water, said medium being inoculated and fermented by at least lactic acid homofermentative biotransforming bacteria, and being inoculated with at least one yeast preparation preferably of bakery type. The ready-to-use liquid sourdough preferably also contains at least one malted cereal flour providing amylases or any equivalent source of amylases. It thus contains 108 colony-forming units (CFU) of lactic bacteria per gram, of which 60% are homofermentative biotransforming lactic acid bacteria, at least 106 colony-forming units (CFU) of yeast per gram, has a final stable pH between 3.8 and 4.5, and a dry matter content between 27 and 35%. It contains at least 7 g of acetic acid, preferably 15 to 20 g/kg of lactic acid and 7 to 10 g/kg of acetic acid.

Ideally, the yeasts used for making a sourdough can be Saccharomyces chevalieri yeasts, and the homofermentative bacteria are species of Lactobacillus plantarum and/or casei, while the heterofermentative strains are species of Lactobacillus brevis.

In certain manufacturing methods, the fresh yeast liquid product, preferably fresh, in particular liquid yeast cream and liquid sourdough, is stabilized by adding one or more food stabilizers. These stabilizers delay or prevent the sedimentation of yeast cells from the suspension. Thanks to their presence in the suspension, the fresh yeast liquid product, preferably the yeast cream or liquid sourdough, maintains its homogeneity for a longer period when stored without agitation. Among the various food stabilizers useful for stabilizing yeast cream, gums such as xanthan gum, and thermally and/or chemically modified starches, such as diacetylated distarch phosphate meeting the definition of modified starch E1422, can be mentioned. Such stabilized yeast creams are, for example, described in EP-A-0 792 930.

Yeast or sourdough preparations may also contain additives or aids that have a role in improving bread quality and/or maintaining the homogeneity of the suspension. These additives can be oxidizing agents such as ascorbic acid, reducing agents such as L-cysteine, enzymatic preparations exhibiting one or more enzymatic activities such as amylase, xylanase, lipase and/or phospholipase, or oxidases such as glucose oxidase. These additives can also be one or more osmotic agents, such as for example polyhydroxy food compounds and food salts.

Conservation of Liquid or Semi-Liquid Ingredients Producing Gas

The present invention also relates to the use of a packaging as described above for preserving a liquid or semi-liquid ingredient that produces gas, particularly a liquid or semi-liquid ingredient containing yeast as described above. Such packaging is especially used at temperatures below 8°C, preferably between 0°C and 6°C, with a relative humidity ranging from 50% to 100%, and allows for good preservation of liquid or semi-liquid products containing yeasts for at least 4 weeks, preferably for at least 6 weeks, and more preferably for at least 8 weeks.

Under these storage conditions, such packaging can also be used with a potential temperature variation of up to 35°C for a maximum period of 8 hours, preferably for 4 hours, and even more preferably with a temperature variation of up to 20°C for a maximum period of 2 hours.

Unless otherwise defined, all technical and scientific terms used in the description have the same meaning as commonly understood by an ordinary skilled person in the field to which this invention belongs. Similarly, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference.

Examples

The following examples describe certain embodiments of the present invention. However, it is understood that the examples are provided only for illustrative purposes and in no way limit the scope of the invention.

Example 1

Multi-layer films based on Ethylene Vinyl Acetate (EVA) were prepared using well-known industrial inflation extrusion techniques. Two films, film 1 and film 2, were obtained with thicknesses of 30 µm and 40 µm, respectively. The central layer A of each film consists of an EVA with a vinyl acetate content by weight between 18% and 42%, while the outer layers B and B' are made of EVA with a lower vinyl acetate content than that of the EVA in layer A.

Permeability measurements. The oxygen and carbon dioxide transmission coefficients were determined on a film sample under standard conditions and after conditioning in a climate chamber at 23°C and 90% relative humidity (RH) for 48 hours.

The oxygen and carbon dioxide permeability coefficients were determined using a LYSSY GPM5000 apparatus. Each sample was placed in a 50 cm² test cell between two chambers, with the lower chamber constantly purged by a helium flow, and the other chamber being in contact with the test gas (a CO2/O2/N2 mixture in proportions of 1/3, 1/3, 1/3). Any gas that passes through the film sample is carried by the carrier gas to a gas chromatograph equipped with a thermal conductivity detector. The experimental conditions used were as follows: carrier gas: helium, test gas: a 1/3, 1/3, 1/3 mixture of CO2/O2/N2, test temperature: 23°C, the films were tested as received and after conditioning at 23°C and 90% RH for 48 hours.

The thickness of the film sample was measured using a precision micrometer ADAMEL LHOMARGIE (accuracy 1 µm). The measurements were performed on three different samples of each film.

Results. The results obtained are presented in the following Tables 1 and 2, where PCO2 and PO2 are expressed in 1/m²/24h/atm. Tableau 1. Epaisseur et coefficients de transmission de l'oxygène et du carbonique pour trois échantillons du film 1.

Conditions standard	Echantillon 1	28	87	14
	Echantillon 2	27	87	21
	Echantillon 3	26	93	18
Après conditionnement	Echantillon 1	25	101	19
	Echantillon 2	28	111	23
	Echantillon 3	20	123	26

Tableau 2. Epaisseur et coefficients de transmission de l'oxygène et du carbonique pour trois échantillons du film 2.

Conditions standard	Echantillon 1	36	66	12
	Echantillon 2	37	80	15
	Echantillon 3	34	87	16
Après conditionnement	Echantillon 1	39	78	14
	Echantillon 2	37	91	18
	Echantillon 3	39	88	19

The permeabilities of the films before and after conditioning do not differ significantly.

Example 2

From the films of Example 1, pouches of 10 and 20 kg were prepared, intended for packaging liquid yeast and/or yeast cream. The empty pouches have a rectangular or square shape with internal dimensions of 500x680 for the 20 kg pouches and 500x500 for the 10 kg pouches.

The bags were reinforced with a second multi-layer film having the following composition: a 20 µm OPA (Nylon) layer with a density of 23 g/m², an adhesive layer, and an 80 µm LLDPE/LDPE layer with a density of 74 g/m².

The second film is perforated, containing 7090 perforations per square meter. The sachets have been equipped with a threaded base positioned 105 mm from the upper seal.

Sample bags were used as controls. These sample bags consist of a slightly permeable polyethylene film to CO2 (permeability of 17 to 27 l/m²/24h at delta P = 1 bar), and are equipped with a degassing cap allowing the evacuation of carbon dioxide released during storage and transportation.

Gas emission measurement test. The objective of this test was to evaluate the amount of CO2 released during storage through a Bag-in-Box (BIB) according to the invention (i.e., "cardboard + bag according to the invention") and through a control BIB (i.e., "cardboard + control bag"), after each had been filled with a liquid product containing yeast from the same batch. For this purpose, each filled BIB was placed entirely in an airtight bag. Thus, any gas escaping from the packaging system became trapped in the bag. Each day, the gas was removed from the airtight bag and measured using the principle of a graduated cylinder: the system, similar to a graduated cylinder, is first filled with water. Then, the tap of the bag containing the BIB and the graduated cylinder is opened. The gas displaces the water, and the volume of gas released is measured. The results obtained are reported in the following Table 3. Tableau 3. Quantité de CO₂ qui s'évacue des différents BIB testés en fonction du temps de stockage.

1	1860	1220	2220	2100
2
3	2320	2480	4320	4400
4
5
6	3500	3680	7120	7200
7	1100	1040	2300	2300
8	1080	1140	1280	1260
9	360	800	1460	1320
10	1080	1180	2300	2200
11
12
13	2580	2840	4940	5340
14	890	1600	1120	1290
15	900	1140	1300	1440
16
17	1980	1960	3560	4200
18
19
20	3060	3180	5200	5400
21	980	920	1260	1320
22	1200	1200	2080	2180
23	1000	980	1260	1500
24	1080	980	2080	1560

As can be seen in Table 3, the behavior of the BIBs according to the invention and the control BIBs is identical, whether considering the average amount of gas evacuated per day or the total volume of CO2 evacuated during the 24 days of testing (as shown in Table 4). Tableau 4. Quantité totale de CO₂ évacués des différents BIB en 24 jours de stockage.

	25	27	44	45

Claims (15)

1. Use of a three-layer plastic film with a B-A-B' structure as wrapping for a liquid or semi-liquid ingredient that produces gas, said liquid or semi-liquid ingredient comprising a leaven or a yeast and having a viscosity of less than 20 000 mPa.s (centipoises), preferably less than or equal to 1 000 mPa.s (centipoises) measured at a temperature of approximately 10°C using a standard viscometer such as described in the specification, characterized in that:

   - layer A consists of an ethylene-vinyl acetate (EVA) with a vinyl acetate content, as percentage by weight, between 18% and 42%, and

   - each of layers B and B' consists of an ethylene-vinyl acetate (EVA) having an ethylene-vinyl acetate content which is less than that of the ethylene-vinyl acetate of layer A, and characterized in that:

   - the permeability of the film to carbon dioxide, measured according to ISO standard 15105-2:2003 annex B, is greater than or equal to 80 l/m².24 h at delta P = 1 bar,

   - the film has a total thickness of from 20 to 50 microns, preferably of 30 microns, and

   - the permeability of the film to oxygen (O₂), measured according to ISO standard 15105-2:2003 annex B, is less than or equal to 30 l/m².24 h at delta P = 1 bar.
2. The use according to claim 1, characterized in that the permeability of the film to carbon dioxide, measured according to ISO standard 15105-2:2003 annex B, is greater than or equal to 90 l/m².24 h at delta P = 1 bar.
3. The use according to claim 1 or claim 2, characterized in that layers B and B' are identical.
4. The use according to claim 1 or claim 2, characterized in that layers B and B' are different.
5. A plastic material composed of two plastic films, characterized in that the first plastic film is a three-layer plastic film as defined in any one of claims 1 to 4, and the second plastic film is uniformly perforated or has a permeability to carbon dioxide which is greater than or equal to that of the first plastic film.
6. The plastic material according to claim 5, characterized in that the second plastic film, when perforated, contains at least 1000 perforations/m², preferably at least 5000 perforations/m² and even more preferentially about 7000 perforations/m².
7. The plastic material according to claim 5 or claim 6, characterized in that the second plastic film is composed of oriented polyamide (OPA) and polyethylene (PE) or of polyethylene terephthalate (PET) and polyethylene (PE).
8. A packaging comprising a reservoir/container composed of a plastic material according to any one of claims 5 to 7, characterized in that the first plastic film of the plastic material defines the internal volume of the reservoir/container.
9. The packaging according to claim 8, characterized in that the reservoir/container is in the form of a pouch having a total internal volume of between 1 l and 1000 l, preferably between 10 l and 200 l, and more preferably between 1 l and 50 l.
10. The packaging according to claim 9, characterized in that the pouch comprises a base and a cap.
11. The packaging according to claim 10, characterized in that the packaging is in the form of a Bag-in-Box and also comprises a cardboard box comprising an opening.
12. Use of a plastic material according to any one of claims 5 to 7, for manufacturing a container/reservoir intended to receive a liquid or semi-liquid ingredient which produces gas, preferably carbon dioxide, said liquid or semi-liquid ingredient comprising a leaven or a yeast and having a viscosity of less than 20 000 mPa.s (centipoises), preferably less than or equal to 1 000 mPa.s (centipoises) measured at a temperature of approximately 10°C using a standard viscometer such as described in the specification.
13. Use of a packaging according to any one of claims 8 to 11 for the storage and use of a liquid or semi-liquid ingredient which produces gas, preferably carbon dioxide, said liquid or semi-liquid ingredient comprising a leaven or a yeast and having a viscosity of less than 20 000 mPa.s (centipoises), preferably less than or equal to 1 000 mPa.s (centipoises) measured at a temperature of approximately 10°C using a standard viscometer such as described in the specification, characterized in that the packaging allows evacuation of the gas produced.
14. Method for the storage and use of a liquid or semi-liquid ingredient which produces gas, preferably carbon dioxide, said liquid or semi-liquid ingredient comprising a leaven or a yeast and having a viscosity of less than 20 000 mPa.s (centipoises), preferably less than or equal to 1 000 mPa.s (centipoises) measured at a temperature of approximately 10°C using a standard viscometer such as described in the specification, comprising the following steps:

    - packaging of the ingredient which produces gas in a packaging according to any one of claims 8 to 11,

    - storage, at a temperature of between 0 and 6°C and in a relative humidity of between 50% and 100%, of said packaged ingredient until use, and

    - use of the liquid or semi-liquid ingredient which produces gas.
15. The use according to any one of claims 1 to 4, 12 and 13 or the method according to claim 14, characterized in that the liquid or semi-liquid ingredient which produces gas is a liquid yeast or a cream yeast.