The present invention concerns an active package with a preservative action upon contact for the industrial, artisan and domestic packaging of foodstuffs, fresh or otherwise, vegetables, fruit, plants, flowers or any other product which can be perishable in a short time if not correctly preserved.
In the technology of packing materials, particularly in the field of packing food products, the need to provide a wrapping which is suitable to prolong, by at least some days, the sensorial characteristics of the wrapped food is becoming more and more urgent.
To be more exact, there is a need to achieve food safety by respecting as far as possible the nutritional and organoleptic contents of the packaged product.
To obtain this result, technological solutions have been developed suitable to create a series of obstacles to the survival and multiplication of microbes, acting for example on temperature, pH, modified atmosphere, drying and lyophilization, preservatives (additives).
The nature of said obstacles, their number and also their entity are decisive not only in determining the survival and multiplication of microbes, but also in controlling some chemical and enzymatic reactions of a modifying nature.
The study and development of a wrapping able to reduce to a minimum the modifications of the food in the course of preservation, and hence able to extend the duration of said food or, at times, simply to allow the food to have a better presentation (unchanged color, less greasiness, etc.), come within this framework.
During the preservation, the atmosphere inside a wrapping is continually modified, due to the gases and the humidity produced by the metabolic processes, and due to the different permeability of the materials used in the package. It is often necessary to have recourse to multilayer coverings, since they have good barrier characteristics and other properties fundamental for food use, such as biocompatibility and weldability.
There are many solutions known in the state of the art which provide to modify the atmosphere which surrounds the foodstuff in order to improve its preservation. Traditional technologies involve the use of controlled atmospheres (which concern the preservation of the foodstuffs or their transportation, in conditioned cells, where the atmosphere can be closely controlled), and the technology of packaging in a modified or protective atmosphere (MAP), which concerns the individual packing.
In this last case, the natural atmosphere is replaced by mixtures of gases, mainly but not only oxygen, nitrogen and carbon dioxide. Some more recent solutions, on the contrary, refer to a so-called "functional package", or "active package".
The function of the active package is to interact with the internal atmosphere, varying the composition thereof, and/or with the product, releasing or capturing components in order to maintain the quality for a longer time. Moreover, thanks to the presence of an indicator, the active package "tells" the consumer the heat history of the product and therefore the current level of quality. Such solutions are particularly interesting for the preservation of fresh products or with minimal processing, as in the case of the above-mentioned theory of obstacles.
The functions performed by the active packages, and the relative applications, are mainly as follows:
The residual oxygen in the packaging, due to the effect of the chemical removal effected by the absorber, has been estimated in the range of 0.01%, much less than the value obtainable with other technologies.
Another known solution provides to use a package that provides to release a wide-spectrum biocide (ClO2), also active in very low concentrations (in the order of some parts per million).
However, the need has arisen in the field to replace high barrier synthetic packages by means of the synergic use of an active wrapper which covers the foodstuffs, partly limiting the exchanges with the outside environment and without modifying the packaging atmosphere.
In this way, apart from the numerous advantages already explained, the use of degradable active films also brings advantages in the direction of a greater attention for environmental respect.
The purpose of the invention is therefore to achieve an active package of the degradable and completely recyclable type which can on the one hand ensure an extension of the useful life of the packaged product, guaranteeing that the organoleptic, visual and taste characteristics of the product are maintained, and on the other hand to obtain an active package that can be produced with limited costs and having an aesthetic and tactile appearance similar to that of normal products currently available.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain other advantages.
The present invention is set forth and characterized essentially in the main claim, while the dependent claims describe other innovative characteristics of the invention.
In accordance with this purpose, an active package with preservative action according to the present invention consists of a film, a strip or a tube (hereafter we shall speak mainly of a film, but this shall include a strip or a tube), made starting from a mixture comprising at least a certain quantity of a polyethylene or polypropylene, charged with at least a support additive component suitable both to increase the consistency and resistance of the polyethylene or polypropylene, and also to provide it with a desired aesthetic and tactile appearance, for example similar to paper.
According to the invention, the support additive component is selected from a group consisting of CaCO3, zeolites and silicates.
In a known manner, other components usual in the field of packaging may be added to the mixture, such as for example talc, sliding agents, anti-blocks, powdery or adsorbent inert materials, possible colored pigments or other.
According to a characteristic feature of the invention, the mixture that forms the film, strip or tube, further comprises at least a food type additive, with preservative capacities, in particular but not only anti-oxidizing capacities.
The food type additive with preservative capacities is of the organic type.
According to the invention, the food type additive with preservative capacities is chosen between one or more of the following elements: ascorbic acid, acetic acid, sorbic acid, propionic acid, lactic acid, citric acid or the salts thereof, or a mixture of two or more thereof.
According to a variant, the food type additive with preservative capacities comprises a mixture of two or more of the above acids.
According to another variant, the food type additive with preservative capacities comprises a salt of one or another of the acids listed above, a combination of the salts of two or more of the acids listed above or a combination of one or more of the salts of the acids listed above and one or more of the acids themselves.
The presence of a food type additive with preservative capacities, distributed in the mixture which makes up the film used for the package, provides the film itself with the property of limiting the oxidation, and in general the alteration of the product due to contact and reaction with the packaged product, at the same time ensuring that the characteristics of color, flavor and relative humidity of the product are maintained.
The presence of particles of a food type additive, distributed as uniformly as possible on the surface of the film used for the package, ensures a contact, and hence a reaction, which are distributed over a large surface of the product, so that no areas are created with a different level of deterioration from others.
According to a first embodiment of the invention, the additive component that functions as a support for the polymeric material consists of CaCO3.
According to an advantageous variant, the additive component that functions as a support consists of zeolites, which can completely or partly replace the CaCO3.
The presence of zeolytes as a support component for the polymeric material amplifies the preservative capacities of the food type additive. This is because the particles of the additive are incorporated with and grip onto the particles of zeolite, greatly reducing the migration and dispersion into the atmosphere thereof, and promoting their release towards the product to be preserved.
According to another variant, the additive component that functions as a support consists of silicates, for example natural silicates such as clay or sand, or artificial silicates such as glass or a compound comparable to glass.
Within the framework of the production process, the food type additive with preservative capacities can be introduced both before the formation of the compound, consisting of the polymer mixed with the support component, and also after the compound has been formed, at the moment the film is formed that makes up the package.
In order to form the active package with preservative action it is possible to use the following quantities:
According to another variant embodiment, titanium dioxide (TiO2) is added to the compound, to a percentage comprised between 0.1 and 20% in weight, advantageously between 1 and 10% in weight of the overall weight of the mixture.
The addition of titanium dioxide can attribute a whitening effect to the active package and can provide a synergic effect in order to increase the preservative action of the package.
The package obtained can have a preferred thickness varying from 1 µm to 10000 µm according to the application in which it is used.
The package according to the invention can be used in the form of a thin film, up to 80 µm, and made in a roll so as to wrap fresh foodstuffs such as cold cuts of meat, cheeses, vegetables or suchlike; or in thicker films or strips made in sheets so as to wrap flowers, plants, soil, or other similar material; or again in films, strips or tubes of a greater thickness, 300-10000 µm to make pots, bags or containers, for example intended for freezing processes or the simple transport of perishable goods.
According to another variant, the package can be obtained by means of expansion (solid foam), reaching thicknesses even much greater (from some millimeters to some centimeters).
The attached figure shows, simply as an example, a cut-away view of an active package with preservative action according to the present invention.
The reference number 10 denotes a plastic film produced according to the teaching of the present invention starting from a mixture that has, as its main components, a polyethylene, for example high, medium or low density polyethylene, or a polypropylene, and a support additive component, such as CaCO3 or preferably zeolites, or again, silicates such as clays or glass.
The reference number 11 denotes the particles of zeolites distributed on the surface and on the thickness of the plastic film 10.
The reference number 12 denotes the particles of a food type additive with preservative capacities introduced into the mixture with which the plastic film 10 is formed.
The food type additive can advantageously be ascorbic acid, or one of its salts, or citric acid, or one of its salts, or propionic acid or one of its salts, or a combination of two or more of these.
In other embodiments of the invention, the food type additive can be acetic acid, or one of its salts, sorbic acid, or one of its salts, lactic acid, or one of its salts, or a combination of two or more of these.
The particles of food type additive 12 which anchor and are supported by the particles of support additive component 11 develop their preservative function better and in a more extensive manner, since their tendency to migrate and disperse in the atmosphere is reduced.
It is clear, however, that modifications and/or additions of parts may be made to the active package with preservative function as described heretofore.
For example, one embodiment of the invention may provide to add titanium dioxide to the mixture, to a quantity comprised between 0.1 and 20% in weight, advantageously between 1 and 10% in weight of the overall weight of the mixture.