EP4705102A1

EP4705102A1 - Thermoplastic composition for a biodegradable and compostable packaging intended to come into contact with food

Info

Publication number: EP4705102A1
Application number: EP24727504.3A
Authority: EP
Inventors: Nicola De Mattia; Giuseppe DARGENIO
Original assignee: Rigenera Di Sfrecola Cosimo Damiano
Current assignee: Rigenera Di Sfrecola Cosimo Damiano
Priority date: 2023-05-03
Filing date: 2024-05-03
Publication date: 2026-03-11
Also published as: IT202300008682A1; CN121219132A; KR20260007219A; WO2024228161A1; AU2024266094A1

Abstract

In particular, a biodegradable and compostable fdm for food is described, having one or more layers, suitable for making packaging capable of increasing the shelf life of fruit and vegetables.

Description

THERMOPLASTIC COMPOSITION FOR A BIODEGRADABLE AND COMPOSTABLE PACKAGING INTENDED TO COME INTO CONTACT WITH FOOD

Applicant: RIGENERA DI SFRECOLA COSIMO DAMIANO (P. IVA 05748550729) with head office at: via Foggia, 127 - 76121 Barletta BT

Inventors: Nicola DE MATTIA and Giuseppe DARGENI

Description

A thermoplastic biodegradable and compostable composition intended to come into contact with food is described.

Furthermore, some possible suitable embodiments of packaging, intended to come into contact with food, made of a biodegradable and compostable material, are described.

In particular, a flexible packaging (for example in the form of a film, a bag or a pouch) and a rigid packaging (for example in the form of a so-called clamshell container) are described.

The packagings described below are intended in particular to the packaging and conservation of fresh fruit and vegetables.

Such packagings could also be used for packaging and storing perishable fresh products other than fruit and vegetables, such as fresh floral products.

Conservation of fresh fruit and vegetables during the storage period in the sales points represents an important technical challenge.

The length of time that a fruit and vegetable product can be stored without deteriorating, and can therefore remain on sales shelves, is also known as "shelf life".

Various solutions are known to try and solve the problem of extending the shelf life of fresh fruit and vegetables.

For example, the use of packaging designed to be able to absorb the substances that accelerate the deterioration of fruit and vegetables and / or release substances with a positive impact on their shelf life and / or positively interfere with the packaged product, its atmosphere or the microorganisms present therein is known.

Such packaging is also commercially known as “active packaging”.

In particular, the use of packagings containing zeolites to remove the ethylene that accumulates inside the package following the process of of fruit and vegetables is already known.

The currently known packaging used in the preservation of fruit and vegetables is not entirely satisfactory. ES 1 220 467 U1 describes a film, which is neither degradable nor compostable, for the packaging of fruit and vegetables, having at least three layers, at least one of which is added with zeolite for absorbing the ethylene that fruits and vegetables release in their the process of maturation.

WO 2022/043441 describes, in particular, a film material for food packaging that comprise three layers: a central layer made from a biodegradable polymer, and two barrier layers arranged on both sides, to reduce the oxygen permeability of the film. The two barrier layers are made from a polymer substrate on which SiO_x (that is silicon oxide in which the quantity of oxygen is not certainly determined) or AI2O3 (aluminium oxide) or polyvinyl alcohol is arranged. WO 2022/043441 does not foresee the use of ethylene absorbers.

US 2001/0031299 describes an ethylene adsorbent comprising a silver-doped hydrophobic zeolite, to improve ethylene absorption.

ES 2 939 544 Al describes a film, for packaging fruit and vegetables, having at least three layers, one of which is added with zeolites (having the function of absorbing the ethylene released by fruit or vegetables during their process of maturation) and another layer added with a mixture of zinc oxides and silver ions (to limit the proliferation of bacteria).

In some embodiments the various layers of the film can be made from biodegradable polymers.

However, due to the high presence of zinc oxide, the film described in ES 2 939 544 Al is not compostable. One aim of the inventors is to at least partially solve the problems of the prior art and, in particular, the above- mentioned problems.

In particular, one aim of the inventors is to provide a packaging for fruit and vegetables that is biodegradable and compostable.

Another aim of the inventors is to provide a packaging for fruit and vegetables that allows the shelf life of the preserved product to be extended.

A further aim of the inventors is to provide a packaging for fruit and vegetables having an adequate transparency.

It is also an aim of the inventors to provide a packaging for fruit and vegetables having an adequate mechanical resistance.

Some possible solutions for overcoming the drawbacks of the prior art, are described below with reference to the attached drawings in which:

- figure 1 shows a portion of a film, suitable for packaging and preserving fresh fruit and vegetables;

- figure 2 shows a bag obtainable starting from the film in figure 1, suitable for packaging and preserving fresh fruit and vegetables; and

- figure 3 shows a clamshell container (made by thermoforming) suitable for containing and preserving fresh fruit and vegetables;

- figure 4 shows some fresh strawberries at the time of purchase;

- figures 5a - 5d show some strawberries, after a three day-storage in the refrigerator at 5 °C, when packaged in four different types of bags, as described later;

- figure 5e shows some strawberries after a three day-storage in the refrigerator at 5°C, when packaged in the original packaging, known in the art;

- figures 6b and 6d show the same strawberries as the samples in figures 5b and 5d, after a seven day-storage in a refrigerator at 5 °C;

- figure 6e shows the same strawberries as the sample in figure 5e, after a five day-storage in the refrigerator at 5 °C, when stored in the original packaging; - figure 7 shows the same strawberries as the sample in figure 5d, after a ten day-storage in the refrigerator at 5 °C, and

- figure 8 shows the same strawberries as the sample in figure 5d, after a twelve day-storage in the refrigerator at 5 °C.

With reference to the attached drawings, a packaging in the form of a film is indicated with reference number 1, a packaging in the form of a bag or sack (which can be obtained starting from the film 1) is indicated with reference number 2, and a packaging in the form of a container with a lid of the so-called clamshell type is indicated with reference number 3.

The packagings 1, 2, 3 - shown in the attached drawings - are made of a thermoplastic biodegradable and compostable material, intended to come into contact with food, which will be better described later.

The film 1, for example, can be used for wrapping fruit and vegetables.

The bag 2, for example, can be used for storing fruit and vegetables.

The mouth of the bag 2 can be closed after inserting the fruit and vegetables, for example by making a knot, or simply folding the edges on themselves, or by means of heat sealing.

The clamshell container 3, for example, can be used for storing fruit and vegetables.

In a particular embodiment, the packagings 1, 2, 3 are single-layer packagings, that is to say they are made of a single layer of thermoplastic material.

In particular, the film 1 can be obtained by using a conventional single-layer blown extrusion plant, fed with a thermoplastic material in the form of biodegradable and compostable pellets, which is intended to come into contact with food. The film can be processed in the form of a bag or a sack, or in the form of a substantially rigid container, for example a clamshell tray.

Conversely, the bag 2 can be obtained by using a conventional plant for producing bags fed with a film material, for example a tubular film (in particular a single -layer tubular film), or a single-fold film (in particular a single-layer single -fold film).

The material in the form of a film used to make the bag 2 is a thermoplastic biodegradable and compostable material, intended to come into contact with food.

The clamshell container 3 can be obtained by thermoforming a sheet of a single-layer material, which is in turn obtained by using a conventional flat-head single-layer extrusion plant, fed with a thermoplastic biodegradable and compostable material, in the form of a pellet, intended to come into contact with food.

As better clarified below, the packagings 1, 2 and 3 are particularly advantageous for preserving products such as fresh fruit and fresh vegetables, significantly extending their shelflife.

The adjective "thermoplastic" as used herein, particularly refers to a material that can be shaped under the action of heat and, in particular, a material that can be processed through the so-called blown extrusion or flat die extrusion.

The term "pellet", as used herein, refers to granules of plastic material, generally cylindrical or lenticular in shape, preferably with a maximum dimension of less than 5 mm. A definition of "intended to come into contact with food" can be found in EC regulation 1935/2004 to which reference is made.

The adjective "biodegradable and compostable", as used herein, means a material that can be transformed - under the action of bacteria and microorganisms and under certain conditions of temperature, humidity and oxygen concentration - into oxygen, carbon dioxide and compost.

The term "compost" means a biologically stable, inert, odorless organic substance consisting mainly of humus, active microorganisms and microelements, which can be used as a fertilizer.

The characteristic "compostable", as used herein, means in particular a material whose composition does not give rise to the release of heavy metals.

As used herein, the characteristic "compostable" claimed herein also indicates a material that can be transformed into compost without the presence of ultraviolet rays.

A definition of "biodegradable and compostable" material is set forth in the Italian Technical standard, harmonized at European level, UNI EN 13432:2002 (Requirements for packaging recoverable through composting and biodegradation - Test schemes) and UNI EN 11451:2012 (Compostable and biodegradables bags for urban solid waste collection - Types, requirements and test methods).

For a definition of active packaging, reference is made to EU Regulation n.450/2009.

The composition of the pellets used to extrude the material used to make the packagings 1, 2, 3 comprises: a polyester polymer or a mixture of thermoplastic, biodegradable and compostable polyester polymers; zeolites, in a weight percentage between 0.1% and 60%; and an antibacterial, substantially and / or essentially free of metals or metal-based compounds, such as metal oxides and metal salts.

Zeolites and the antibacterial are distributed in the polymeric mass of the pellet and therefore of the packaging material 1, 2, 3.

The zeolites present in the polymeric matrix perform, in particular, the function of counteracting the processes evolving during the aging phase, effectively slowing down the ripening of the packaged products.

Preferably, zeolites are present in a weight percentage between 0.1% and 10%, more preferably between 0.1% and 2%.

Zeolite percentages greater than 2% by weight lead to a decrease in the transparency of the material used to make the packaging.

Higher percentages of zeolites can be used, for example, to make rigid, non-transparent containers which can be provided with lids or closure films in a transparent composition.

The term "antibacterial" is herein intended to indicate a biocidal compound capable of counteracting the proliferation of bacteria and other microorganisms such as yeasts and moulds, which are naturally present on the surface of fruit and vegetables.

The antibacterial compound, or biocide, is present in a weight percentage of the weight of the thermoplastic composition between 0.02% and 10%, preferably between 0.1% and 1.5%. A preferred biocide is citric acid.

Salified forms of citric acid are preferably not used.

The absorption of ethylene the packaged products release and the contrast to the proliferation of microorganisms create a synergistic effect in extending the shelf life of the packaged fruit and vegetables.

In other words, it has been surprisingly found that the combination of zeolites and a biocide, in particular zeolites and citric acid, makes it possible to extend the ripening times of food by at least 100% compared to traditional packaging and by at least 100% compared to packaging that uses only zeolites or only the biocide. For example, it has been experimentally verified that the ripening time, that is to say the shelf life of the product in terms of days before it is no longer salable, is extended by up to 4 times, for example from 7 to 28 days for mushrooms, as specified in table 2 described below.

The antibacterial being substantially and / or essentially free of metals or metal-based compounds, such as metal oxides and metal salts, means that packagings 1, 2, 3 are suitable for contact with products intended for food consumption, turning out to also be compostable.

In particular the antibacterial used to make the packagings 1, 2, 3 is free of zinc oxide (ZnO) which is a compound relatively harmful to human health, the presence of which would also affect the packaging compostability.

A biodegradable and compostable thermoplastic polyester suitable for use in the producing packagings 1, 2, 3 can be a polybutyrate-adipate-teraphthalate (PBAT).

In possible embodiments PBAT is present with reduced amounts of PLA (polylactic acid, a compostable polyester) to improve the extrudability of PBAT.

In other embodiments, the biodegradable and compostable thermoplastic polyester used to make the packagings 1, 2, 3 may include at least one thermoplastic polyhydroxyalkanoate (PHA).

Polyhydroxyalkanoate (PHA) refers to a family of polymers (polyesters) consisting of (R)-3-hydroxyalkanoic acids synthesized by bacteria through microbial fermentation processes.

PHAs can be synthesized as homopolymers (equal monomers) or copolymers (different monomers), depending on the bacterial strains used or growth substrates.

Among the PHA homopolymers is polyhydroxybutyrate (PHB).

PHAs are non-toxic, non-water soluble, biodegradable and compostable, and exhibit thermoplastic properties similar to petrochemical plastics.

Poly-3 -hydroxybutyrate (PHB) for example is the most widely studied PHA polymer and exhibits highly crystalline characteristics similar to those of polypropylene.

Depending on the number of carbon atoms in the monomer, it is referred to as short-chain PHA (scl-PHA, 3 to 5 carbon atoms), medium-chain PHA (mcl-PHA, 6 to 15 carbon atoms), and 1-chain PHA.

The molecular weight of PHA can vary depending on the intended use of the thermoplastic composition and will be lower in case it is intended for moulding while it will be higher if it is intended for extrusion (for example blown extrusion).

In some possible embodiments, the PHA used has a molecular weight between 2. 10⁴ and 5. 10⁶ Daltons. It has been found that the addition of PHB can improve the elasticity and compostability of the finished product, particularly products in the form of a film.

In other embodiments, the biodegradable and compostable thermoplastic polyester from which the packagings 1, 2, 3 are made may include polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA).

The molecular weight of PBS can range from 60,000 to 100,000 g/mol.

An example of PBS that can be used to extrude the packagings 1, 2, 3 is Mitsubishi FZ91, which has a degree of fluidity (also called Melt Flow Index or MFI) of 5 g/ 10 min and a melting temperature of 115 °C.

The use of polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA) allows the transparency of the packings 1, 2, 3 to be increased.

In particular, PBSA appears to be more amorphous and therefore more transparent.

In some embodiments a mixture is used which, in addition to one of the polymers discussed above, also comprises a percentage of PLA, or polylatic acid, to improve the workability of the polymer mixture.

In a possible embodiment the antibacterial is made up of, or in any case comprises, citric acid, in particular citric acid in an anhydrous form.

By combining citric acid with zeolites, the shelflife of the packaged fresh fruit and vegetables is significantly increased.

In the illustrated examples, citric acid is present in a weight percentage between 0.1% and 1.0% of the total weight of the polymeric composition.

The inventors have observed that percentages by weight of citric acid higher than 1% cause an excessive increase in the fluidity of the thermoplastic composition during the extrusion phase, making the material production process difficult.

Incidentally, it should be underlined that zeolites and citric acid not only do not affect the compostability of the polymeric material but are both suitable for contact with food and skin.

Preferably zeolites are present in a weight percentage equal to 2% and citric acid is present in a weight percentage equal to 0.7%.

In other embodiments, not illustrated, the packagings 1, 2, 3 can be a multilayer packaging.

For example, the film 1 can comprise a plurality of layers of a thermoplastic biodegradable and compostable material, intended to come into contact with food, each layer of which is added with zeolites and an antibacterial, and substantially or essentially free of metals or metal-based compounds, such as metal oxides and metal salts.

Preferably the "antibacterial" compound is a biocidal agent compatible with said thermoplastic polymer and selected from: benzoic acid; citric acid; sorbic acid; bacteriocins; essential oils having a biocidal action, preferably selected from tea tree, lavender, thyme, onion, eucalyptus, lemon essential oils; chitosan and ketin; polyphenols; graphene; terpenes; peptides and cinnamaldehydes or mixtures thereof.

It should be noted that the acids listed above are preferably used in their unsalified forms.

A preferred compound is citric acid which is in a solid, powder form. Antibacterials in the form of oils or otherwise liquids are generally added to a carrier, such as epoxidized soybean oil which acts as a plasticizer, before being added in a known manner to the polymer in the mixing extruder.

At least the layer intended to come into contact with fruit and vegetables is for example loaded with zeolites and an antibacterial.

In multi-layer embodiments, all the layers are preferably added with zeolites and antibacterial.

Having more layers can improve can improve the mechanical properties of the film 1 and the bag 2 and the tray 3 in particular the resistance to tearing can increase.

PHA, PBS and PBSA all have the advantage of being heat sealable, and are therefore suitable for producing packaging in the form of bags.

Zeolites and citric acid have a grain size which is smaller than the thickness of the extruded material.

The composition of the pellet, and therefore of the packagings 1, 2, 3, can comprise a starch, for example a thermoplastic starch, in a weight percentage which is < 30%.

Adding starch can help to reduce the production costs of the packagings 1, 2, 3, even if this involves a reduction in the transparency of the packaging.

The composition of the pellet the packagings 1, 2, 3 are made from can comprise a filler dispersing agent, in a weight percentage which is < 1%, to maintain a uniform distribution of zeolites and the starch inside the extruded product and therefore obtain a material having a homogeneous composition.

The product marketed as “4102” by the German company BYK can be used for example as a dispersing agent. The composition of the pellet, and therefore of the packagings 1, 2, 3, can comprise a plasticizer for food use, (for example epoxidized soybean oil, glycerin, water, sorbitol or a mixture thereof) to improve the extrudability and the elongation properties of the finished product.

The percentage by weight of the plasticizer in the thermoplastic composition can be between 0 and 15%.

The pellet with the composition described above can be obtained by introducing all the ingredients, dosed gravimetrically with dedicated dispensers or injected in a known way in case of liquid ingredients, into a conventional extruder, for example a twin-screw extruder.

The extrusion temperatures of the thermoplastic composition described above, at which the film 1 is made, are affected by the type of machine used and the polymer envisaged in the formula.

By way of example, the extrusion temperatures can be between approximately 150 °C and 180 °C.

A thermal melting profile which allows to obtain a temperature of the outgoing melted mass of approximately 20°C above the melt of the compound being processed is generally applied, taking into due consideration the thermolability of the components of the composition.

In some alternative embodiments of the thermoplastic composition and packaging, the antibacterial may comprise a mixture of citric acid and thyme oil.

Thyme oil is more expensive than citric acid, however adding it can be advantageous because it has not only antibacterial but also antifungal properties. In other embodiments, in addition to citric acid the thermoplastic composition comprises sorbic acid for its biocidal and antifungal properties.

In a possible embodiment, the single-layer or multilayer film material 1 has an average thickness between 7 and 20 pm, preferably between approximately 12 and 20 pm, for example approximately 13 pm.

Thicknesses which are less than 12 pm can make the film 1 not very resistant.

Thicknesses which are greater than 20 pm would instead be economically disadvantageous.

In a possible embodiment, the material of the clamshell container 3 has an average thickness in the range between 0.5 mm and 2.5 mm, preferably at least 1 mm.

In a possible embodiment, the packagings 1, 2, 3 are packagings with venting holes 4 (in the case of the clamshell container the holes 4 can be located at least on the lid of the container).

The venting holes 4 give the packagings 1, 2, 3 significant permeability to gases (in particular to oxygen and carbon dioxide) and to water vapour.

Ultimately, the venting holes 4 allow the atmosphere inside the package to be maintained at values capable of minimizing the anaerobic processes that take away the freshness of the food.

The atmosphere inside the space defined by the packagings 1, 2, 3 can be modified by varying the shape, size and number of the venting holes 4.

The choice of shape, size and distribution of the venting holes 4 can vary depending on the type of product contained in the packagings 1, 2, 3 and the quantity of the product packaged in the packagings 1, 2, 3.

In a possible embodiment, the venting holes 4 are substantially and / or essentially circular holes having a diameter between 3 and 8 mm, preferably between approximately 4 and 6 mm (that is to say having a section between approximately 12 mm² and approximately28 mm²).

In particular, the venting holes 4 can have a diameter of approximately 6 mm.

By way of example, a bag 2 measuring 28x42 cm comprises eight venting holes, four for each face or side of the bag.

In general there are at least four holes of the type described above for a surface area between 500 cm² and 1200 cm 2.

In the absence of holes the bag could be left open to allow ventilation.

However, this technique cannot be repeated for long and is not suitable for obtaining the same effectiveness as the venting holes. The number of the venting holes 4 depends on the size of the bag.

In one embodiment the holes discussed above are present in such a number as to provide a ratio between the area in mm² of the holes for each cm² of the surface of the packaging (mm² hole area/ cm² surface) between 0.04 mm²/cm² and 0.4 mm²/cm².

Actually it has been found that the venting holes 4 of this size and distribution significantly increase the shelf life of the fresh products contained in the bag 2.

The inventors hypothesize that the above indicated dimensions of the venting holes 4 allow a more effective drainage of humidity without affecting the effect of the combination of zeolites and the biocidal agent on the ripening times of the product. In particular the above indicated dimensions of the venting holes 4 are deemed to be such that it is unlikely that the humidity created inside the packaging could block the venting holes and accumulate inside the packaging (which problem is highlighted for example by using conventional venting holes having a diameter on the order of 1.5 mm or less).

The packagings 1, 2, 3 thus made have adequate mechanical resistance and are free from risks to the health of the consumers of packaged fruit and vegetables.

Furthermore, the packagings 1, 2, 3 appear to be easily biodegradable and compostable.

Again, the packagings 1, 2, 3 are substantially and / or essentially transparent and allow a visual examination of the packaged fruit and vegetables.

What the inventors have achieved will now be further illustrated with reference to the following examples.

Example 1. Manufacturing of a polymer film according to the invention.

In an extruder, 0.2 kg of zeolites, 0.07 kg of citric acid and 0. 1 kg of fdler dispersant are added to 10 kg of a mixture consisting of PBAT and PLA, to improve the distribution of zeolites and acid citric in the polymer mass.

The loaded polymer is blown extruded and then transformed into a fdm having a thickness of 13 pm.

Example 2. Manufacturing of a transparent polymer film according to the invention.

In an extruder, 0.2 kg of zeolites, 0.07 kg of citric acid and 0.1 kg of fdler dispersant are added to 10 kg of PBSA.

Example 3. Strawberry ripeness test.

The fdm obtained in example 1 is used to produce bags having dimensions equal to 18x28 cm.

The bag comprises 4 holes per side having a diameter of 6 mm.

Substantially identical quantities of fresh strawberries are placed, some in the original packaging, others inside a bag according to the invention.

The strawberries which are packaged in the bag according to the invention are placed in a first refrigerator with a temperature set at 5°C.

The strawberries which are packaged in the original plastic packaging are placed in a second refrigerator, identical to the first one, also with a temperature set at 5°C.

The samples are visually inspected and photographed every day in order to check ripening conditions and the onset of early signs of wilting: assessment of wilted fruit means that the condition of the fruit was such that the fruit would not have been salable.

The conditions of the strawberries of the two samples on the day the test began are classified as "excellent".

It has been verified that the strawberries packaged in the bag according to the invention have maintained excellent conditions up to the 10^th day and good conditions up to the 12^th day, while the strawberries in the original packaging showed the first signs of wilting already on the 5^th day and were wilted on the 7^th day. Example 4. Comparative strawberries conservation tests in the original packaging, in an additive-free bag packaging, in a bag packaging with only zeolites, in a bag packaging with only citric acid and in a bag packaging including zeolites and biocide according to the invention.

Bags measuring 18x28 and including 4 holes per side having a diameter of 6 mm were prepared, bags having the following compositions were prepared to carry out comparative tests: a) only the thermoplastic, biodegradable and compostable polyester material described in example 1, said material being additive-free, in particular without zeolites and citric acid; b) the thermoplastic, biodegradable and compostable material of test a), comprising zeolites in the quantity indicated in example 1 but without citric acid; c) the thermoplastic, biodegradable and compostable material of test a), only comprising citric acid in quantities as in example 1 but without zeolites; d) the biodegradable and compostable thermoplastic material of example 1.

Equal quantities of fresh strawberries of the same type purchased on the same day were distributed in bags a)- d) to form samples a) - d).

An original package of the strawberries was also kept as sample e); the original packaging comprised a tray and a film, both made from polypropylene.

All the packages were kept in refrigerators with a temperature set at 5°C.

The samples are visually inspected daily to check for ripening conditions and the onset of wilting: assessment of wilted fruit means that the condition of the fruit was such that the fruit would not have been salable.

The condition of the fresh strawberries at the beginning of the test have been classified as "excellent".

It has been verified that in sample d), the strawberries packaged in the bag according to the invention have maintained excellent conditions up to the 12^th day, while the strawberries kept in an additive-free bag (test a) were wilted already on the 5^th day and the strawberries of tests b), c) and e) were wilted on the 7^th day.

The strawberries of samples a)-e) have showed the following ripening behaviour, summarized in Table 1 where na (not available) indicates that the sample was in very bad and undetectable conditions.

Table 1

The results of the comparative tests show that in test d), that is to say the ripening test in a packaging (a bag) according to the invention, the ripening time is increased from 5 to 12 days for strawberries.

In other words, strawberries can be stored effectively and are in excellent or good conditions (namely consumable - and salable) for at least nine days longer than a traditional polypropylene packaging as in test e). The same result is obtained for packaging in bags produced with the comparison fdms, test b), zeolites only, or test c), citric acid only, proving the existence of a synergistic effect generated by the presence of zeolites and a biocidal agent.

It is also noted that, for the purposes of preserving strawberries, a biodegradable and compostable polymer packaging (test a) is worse than a traditional polypropylene packaging (test e) all other conditions being equal.

Example 5. Comparative tests on other fruit and vegetables

Along the lines of example 3, other vegetables have been tested to determine the extension of the shelf life, namely the extension of ripening times.

The results are summarized in Table 2 below.

Table 2,

As previously mentioned, the thermoplastic polymer composition of the invention can be in the form of pellets, films or more or less rigid containers closed with a lid or a film.

The film can have a sufficient thickness (for example approximately 13 microns) and be used to produce perforated bags for containing vegetables, in particular fruit and vegetables, to be stored.

The bags can be purchased by the user and used to contain the products to be stored, which products are purchased separately from the bag.

Alternatively, fruit and vegetables to be stored are packaged in a packaging made of the claimed composition, as described above.

Claims

1. A packaging (1), having a thermoplastic biodegradable and compostable composition intended to come into contact with food, having one or more layers and comprising: a) at least one thermoplastic, biodegradable and compostable polyester; b) zeolites, in a weight percentage between 0.04% and 60%; c) an antibacterial, substantially and / or essentially free of metals or metal-based compounds in a weight percentage between 0.02% and 10%.

2. The packaging according to claim 1, wherein said zeolites are present in a weight percentage of the thermoplastic composition between 0.1% and 10%, more preferably between 0.1% and 2.0% and said antibacterial is present in a weight percentage of the thermoplastic composition between 0.1 % and 1.5%.

3. The packaging according to claim 1 or 2, wherein said thermoplastic biodegradable and compostable polyester comprises at least one polymer and selected from a polybutyrate-adipate-teraphthalate (PBAT), or a thermoplastic polyhydroxyalkanoate (PHA) or a polybutylene succinate (PBS) or a polybutylene succinate adipate (PBSA).

4. The packaging according to claim 1, 2 or 3 wherein said antibacterial comprises or consists of citric acid, in a weight percentage between 0.1% and 1.0%.

5. The packaging according to one of the preceding claims, further comprising starch in a weight percentage which is < 30%.

6. The packaging according to one of the preceding claims, further comprising a fdler dispersing agent, in a weight percentage which is < 1%.

7. The packaging according to one of the preceding claims, having a plurality of venting holes (4) suitable for allowing a gas and vapour exchange, said venting holes (4) having a diameter between 3 and 8 mm, preferably between 4 and 6 mm.

8. The packaging according to one of the preceding claims, further comprising a plasticizer for food use, in a weight percentage which is < 15%.

9. The packaging according to one of the preceding claims, further comprising an antifungal.

10. The packaging according to one of the preceding claims, characterized in that it is a single-layer or a multi-layer packaging.

11. A thermoplastic biodegradable and compostable polymer composition, intended to come into contact with food, comprising or consisting of: a) at least one thermoplastic, biodegradable and compostable polyester; b) zeolites, in a weight percentage between 0.04% and 60%; c) an antibacterial, substantially and / or essentially free of metals or metal-based compounds.

12. The polymer composition according to claim 11, wherein said antibacterial is a biocidal agent compatible with said thermoplastic polymer and selected from: benzoic acid; citric acid; sorbic acid; bacteriocins; essential oils with biocidal action, preferably selected from tea tree, lavender, thyme, onion, eucalyptus, lemon essential oil; chitosan and ketin; polyphenols; graphene; terpenes; peptides and cinnamaldehydes.

13. The polymer composition according to 11 or 12, wherein said antibacterial is a citric acid in a weight percentage between 0.1 % and 1.0%.

14. The polymer composition according to one of claims 10 to 13, further comprising the characteristics according to one of the claims 2 to 10.

15. A method for delaying the ripening of vegetables, characterized by packaging said vegetables in a packaging according to one of the claims 1 to 10.

16. Use of a combination of zeolites and citric acid for delaying the ripening of vegetables, preferably fruits, vegetables, mushrooms and flowers.