The object of the present invention corresponds to an antimicrobial packaging based on the use of natural extracts and also to the process followed to obtain this packaging. The packaging corresponding to the object of the invention is characterised in that of its antimicrobial, antifungal and also antioxidant properties.

To achieve the specified objectives, a vehicle is used, herein referred to as the active liquid, which is applied to a support made of plastic materials, paper, cardboard, aluminium etc., of a rigid or flexible format.

The present invention is characterised in that the active liquid can be applied to different packaging in the form of different types of coatings or as a spray.

The active liquid is comprised of resins, which are selected depending on the type of packaging, solvents that give the system fluidity, additives that confer it flexibility and, finally, of active components, which in this case are natural extracts with or without fixatives.

Therefore, the present invention can be included within the area of varnishes used to coat packaging used for the storage and conservation of products, mainly but not exclusively, to store food products, in order to improve the characteristics of the packaging and the packaged product.

To date, active packaging is one of the most important technological innovations to preserve food products. This packaging is designed in order to provide the packed product with an additional protection, using the interaction between the food or product contained in the packaging to improve its preservation and acceptability.

The actions carried out to improve the quality of the products inside the packaging include:

• the addition of some compounds into the package, such as oxygen scavengers, moisture absorbers, ethylene absorbers and others.
• The addition of new components, dissolved or incorporated into the packaging material, such as antioxidants or others.

Examples are disclosed in FR 1 266 546, US 6 106 876 and WO 0 244 055.

These solutions, already known as protective measures and as means to improve the packaged products, present some drawbacks, such as involving the incorporation of foreign bodies inside the package, alteration of the organoleptic properties of the products by introducing foreign elements or irregular distribution of the protective properties.

This can even lead to a complete loss of the intended activity (loss of efficacy) when there is no direct contact between the product to be protected and the packaging, since protection is achieved by direct contact.

It is also a clear drawback to have to make a film in each case with the additional requirement of having to store films of different composition.

Until now, only one type of packaging which includes an antioxidant formulation has been described, also by the authors of this patent. The object of the invention can not under any circumstances be considered a later version of the same patent, since the objective of the first patent was only to prevent oxidation occurring in the packaging, without any antimicrobial or antifungal activity, and used different products to achieve this.

There are no known cases of packaging with antimicrobial and/or antifungal activity where the liquid used for these purposes is incorporated into the manufactured packaging, since in other solutions proposed for similar purposes the elements used to achieve these objectives require this to be incorporated in the formats during the polymerisation process and while obtaining the plastic material.

On the other hand, some processes achieve the same objectives but use chemical compounds obtained synthetically. This is a drawback from the consumer's perspective since these products must first be approved and present potential unknown risks for human health.

To achieve these properties, natural extracts or essential oils are used that form part of an active liquid which is applied as a coating to the packaging. In this way, active agents are immobilised on the packaging material and the system as a whole presents the antimicrobial or antifungal properties. To achieve this antimicrobial and antifungal action, direct contact with the food product to be protected is not required since the protection is given by controlled release of the antimicrobial agents in the active liquid used to manufacture the packaging.

The use of natural extracts has the advantage that all of these are classified as GRAS material (Generally Recognized as Safe) and are derived from plants used as condiments in food products.

Hence, another objective of the invention is to overcome previous drawbacks of:

• incorporating antimicrobial products during the manufacturing process of the packaging, with the incorporation of these to the final manufactured packaging format.
• the need for direct contact between the food products to be protected and the packaging with the protection formulation, since a vapour phase is produced responsible for protection of the food products.
• using chemical products of unique formulation obtained synthetically and with unknown health risks.

The antimicrobial packaging which corresponds to the object of the invention, basically consists in packaging of any material, format and arrangement, to which an active liquid has been applied which, among other elements, contains essential oils with an antimicrobial, antifungal and presumably also an antioxidant action.

The active liquid can be applied to the final format of the manufactured packaging before it is filled with the desired product, therefore it is not necessary to have a large store or active packaging of different characteristics for the different products to be packaged.

The active liquid is comprised of:

• a formulation made up of:
  • o a resin base such as nitrocellulose, acrylic, vinylic or others, chosen depending on the type of packaging to which the liquid is applied, to achieve good adhesion.
  • o Solvents which give the active liquid fluidity.
  • o Additives to give flexibility or other characteristics to the coating.
  • o Natural extracts based on essential oils that contain the active agents together with appropriate fixatives, which produce blocking or immobilization effects of the agents required for the desired antimicrobial and antifungal characteristics and permit controlled release of the active agents.

The natural extracts used, among others, can correspond to cinnamon, clove, ginger, rosemary, oregano, dill, basil etc. or other similar compounds derived from plants, either alone, or combined in appropriate proportions depending on the desired effect. The proportion of extracts ranges from 0.1 % to 10% in weight of the active liquid.

The natural extracts added to the base formulation can be in the form of an essence alone or combined with a fixative which retains the volatile elements of the natural extracts and which play the most active role in inhibiting growth of bacteria, yeasts and fungi.

The desired objective is complete inhibition of growth of bacteria, yeasts and fungi, producing their total elimination and preventing subsequent growth.

Depending on the type and the concentration of the extract used and whether or not it is used as a fixative, complete inhibition or at least a reduction in colony forming units (CFU) is achieved for some types of bacteria, fungi or yeasts.

Since certain food types favour the growth of certain bacteria and/or fungi, different types or combinations of natural extracts are required in each case, in order to achieve complete inhibition of all the possible bacteria, fungi and yeasts that can arise.

In some cases, the combination of natural extracts has been found to have a synergic effect on its inhibition properties, significantly improving the active efficiency.

The following tables are included in an attempt to demonstrate the effect of natural extracts added to a basic formulation applied to packaging, where the following abbreviations are used:

• CFUs per ml = colony forming units per ml
• Control = the standard microorganism culture produced in the Petri dish used in laboratory experiments.
• P0 = the basic formulation without any extract.
• PCA1 = the basic formulation to which cinnamon essence is added at 1% in weight of the active liquid.
• PCA4 = the basic formulation to which cinnamon essence is added at 4% in weight of the active liquid.
• PPeCA1 = the basic formulation to which cinnamon essence is added at 1 % together with a fixative.
• PPeCA4 = the basic formulation to which cinnamon essence is added at 4% together with a fixative.

As can be observed in table 1, the number of colony forming units (CFUs/ml) of bacteria is zero, i.e. there are NO colony forming units for most of the bacteria and for any of the fungi and yeasts for a 4% extract of cinnamon essence with fixative.

Also, in table 2 we can observe that colonies of fungi are not formed with 1% extracts of cinnamon combined with fixative.

Logically, these experiments have been carried out with natural extracts such as cloves, basil, rosemary etc. producing in some cases a decline in the number of colony forming units (CFUs) and a radius of inhibition inside which no colony develops, while in other cases there is total inhibition, i.e. there is no growth of a specific bacteria, yeast or fungus.

The process to obtain the antimicrobial packaging has the following steps:

• Preparation of a basic formulation comprised of a resin substrate, some solvents and some additives to confer the final characteristics to the coating.
• Dispersion and dissolution of natural extracts in the basic formulation that contain antimicrobial and fungicidal active agents. The solution or dispersion is made using Cowles type rotor stator assemblies; wet mills or other similar devices.
• Incorporation of the active liquid to the chosen package or support.
• Drying of the packaging, either in the open air or with forced air.

Incorporation of the active liquid to the package can be done:

• by impregnating the support in the active liquid
• by coating the different forms of the support
• by spraying the active liquid on the support

The packaging to which the liquid is applied can be made of plastic, paper, cardboard, tinfoil, steel, aluminium or glass, either of one material or in several layers. Materials used can be virgin or recycled.

The supports to which the active liquid can be applied are:

• Polypropylene and all its forms
• Polyethylene and all its forms
• Polyester (PET, PETG)
• PVDC
• Polystyrene and all its forms
• PVC
• Polyamide
• Polycarbonate
• Cellulotic films (cellophane) and all its forms
• KRAFT
• Paper and all its forms
• Aluminium
• Tinfoil
• Steel
• Glass

And all the complexes that can be formed from these materials (by adhesion, lamination or extrusion).

As a complement to the present descriptive report and to make it easier to understand, this is accompanied by a set of plans. The most significant aspects of the invention are represented in the figures of these plans, these must be considered as illustrative and in no way limit the scope of the invention.

Figure 1. This shows a schematic representation of the steps of the manufacturing process of the antimicrobial packaging based on the essence of the object of the invention.

Figure 2. This shows a schematic representation of the materials used to manufacture the active liquid applied to the final packaging.

In view of the figures, a preferable application of the proposed invention is described.

Figure 1 represents the steps required for the process to manufacture the antimicrobial packaging which constitutes the object of the invention and consists of the following steps:

• Preparation (1) of a basic formulation, which is comprised of a resin substrate, some solvents and some additives which confer the coating with its final characteristics.
• Dispersion and dissolution (2) of natural extracts that contain the active antimicrobial and antifungal agents in the basic formulation. The dissolution or dispersion is carried out using stirrer systems such as "Cowles" type rotor stator assembly, wet mills or by other similar methods.
• Incorporation (3) of the active liquid to the chosen packaging or support.
• Drying (4) of the packaging, either in the open air or by forced air.

The active liquid can be incorporated to the packaging by:

• Impregnation (3.1) of the packaging by the active liquid in spray.
• Coating (3.2) of the different packaging formats.
• By spraying (3.3) the packaging with the active liquid.

Figure 2 shows that the active liquid (10) is comprised of:

• a basic formulation (5) comprised of
  • o A resin substrate (6) made of nitrocellulose, acrylics, vinylic or other compounds the selection of which is based on the type of support to which they are to be applied, in order to achieve good adhesion.
  • o Solvents (7) which confer fluidity to the active liquid.
  • o Additives (8) to give flexibility or other characteristics to the coating.
• Natural extracts (9) based on essential oils that contain active agents which produce a blocking effect or immobilisation of the active agents that confer the desired antibacterial and fungicidal characteristics.

This description is sufficient for any expert in the area to understand the scope of the invention and the benefits that can be derived from it.

The materials and size, shape and arrangement of the components may vary provided that the essence of the invention remains the same.

The terms used in this descriptive report should always be interpreted in their broadest sense and not in a restrictive way.