CYCLODEXTRINS , PROCESS FOR THE PREPARATION THEREOF, FILMS OBTAINED THEREFROM AND USE THEREOF IN THE PACKAGING FIELD

DESCRIPTION

Technical Field

The present invention relates to gelatins derived, i.e. obtained, from the skin of fish species, in particular fish, modified/formulated with cyclodextrins ; to water-soluble films obtained therefrom; and to the use thereof in the packaging field, preferably for oxygen-tight applications, i.e. acting as a barrier against oxygen.

In particular, the present invention relates to fish skin gelatins, substantially or specifically based on partially or wholly hydrolized collagen (hereinafter referred to, for simplicity, as "hydrolized collagen") , obtained only from secondary raw material (i.e. processing scraps used for producing other products) obtained from various fishes skin, e.g. fish industrial processing scraps; said gelatins being modified/formulated through the addition of suitable amounts of at least one natural, or derived, or semi-synthetic cyclodextrin; to the water-soluble films obtained therefrom and to the use thereof in packaging applications, in particular flexible and/or rigid packaging, disposable and water-soluble packaging, oxygen-tight packaging for any solid or non-water-based liquid products; or in production fields for the production of shopping bags or packaging envelopes, secondary packaging for transport, multi-material packaging (e.g. cardboard-plastic), laminated multi- materials, expanded materials, 3D printing, containers for different uses obtained by means of the known blowmolding technique, or even in fields like label and disposable-glove production. In particular, for the packaging of pharmaceutical and/or electronic products, or in production fields for the production of shopping bags or packaging envelopes, secondary packaging for transport, multi-material packaging (e.g. cardboard-plastic), disposable-glove production .

Background Art

Currently, animal gelatins, in particular those based on (partially or wholly) hydrolized collagen, produced from different raw materials (e.g., the so-called fish or mammalian gelatins), are not particularly or specifically used on a large scale in the packaging field, but they are mainly used as food thickeners or for other applications, the most important of which consists in the preparation of (soft or rigid) soluble capsules for the formulation of pharmaceutical forms. Although the methods for processing/producing animal gelatins through the use of traditional plastic processing techniques such as, for example, casting, blowmolding and extrusion, have been known for a long time (see, respectively, R.J. Avena-Bustillos , C.W. Losen, D.A. Lo son, B. Chiquita, E. Yen, P.J. Bechtel and T.H. McHugh, Water Vapor Permeability of Mammalian and Fish Gelatin Film, Food Engineering and Physical Properties, 2006, Vol. 71, no. 4, pp . 202-207 ; Process For Making Gelatine Films, U.S. Pat. 5,316,717, May 31, 1994; Method For Molding Capsules, U.S. Pat. 4,591,475, May 27, 1986), their utilization in the packaging field has always been considered as not particularly useful because of their strong tendency towards hydration. For this material, hydration is a critical process in that it causes a significant loss of mechanical properties and, in the most severe cases, the partial or total solubilization of the material, resulting in destruction of its structure. At present, no industrial processes or machines are known to the present inventors which are specifically dedicated to the fabrication and molding of this material for the production of a disposable, water-soluble, flexible and/or rigid film for protecting/insulating products against oxygen, with the exception of the machinery employed for molding the above- mentioned water-soluble capsules (see, for example, U.S. Pat. 5,419,916: Gelatin Coating Composition and Hard Gelatin Capsule, July 22, 1993, Japan Elanco Company, Limited) .

By way of example, WO 99/33924 concerns gelatin compositions, preferably derived from fish (in general), poultry or plant sources for use, in particular, in the pharmaceutical, veterinary and food packaging fields. Especially preferred are compositions for preparing hard capsules prepared from fish gelatin. However, the use of fish gelatin becomes acceptable from a practical viewpoint only if other components are added to the fish gelatin, thus forming a so- called setting system, including, for example, one or more hydrocolloids possibly added with cations and/or sequestering agents. Otherwise, fish gelatins have limited application (see, for example, page 2, rows 1-27) . Among the sequestering agents, the possible presence of b-cyclodextrin is also mentioned, although only in general terms (page 6, row 1 ) .

CN 104693811 describes a food packaging film, wherein a carboxylated b-cyclodextrin is embedded with a gelatin. No specific type of gelatin is mentioned, let alone gelatin obtained from fish skin.

WO 2006/095026 A2 describes soft gelatin capsules for oral administration, consisting of a shell including a cyclodextrin for increasing the bioavailability of a drug contained therein. Gelatin is mentioned in general terms only; no mention or suggestion is made to gelatin obtained from fish skin. WO 2006/095026 A2 mentions the above- described publication WO 99/33924 as a prior art.

WO 99/46329 is essentially a continuation of WO 99/33924 and describes, in particular, compositions for use in the pharmaceutical, veterinary and food packaging fields, wherein gelatin is preferably replaced with PVA. A comparison is made between the properties of the PVA-based compositions and those of the gelatin-based ones of WO 99/33924. No specific mention or suggestion is made to gelatin obtained from fish skin.

CN 108690357 describes a method for preparing a film obtained from a specific rabbit-skin gelatin with b-cyclodextrin . No specific mention or suggestion is made to gelatin obtained from fish skin.

The most important attempts made so far to solve this problem can be classified into three categories: a) crosslinking, b) addition of hydrophobic agents, and c) production of multilayer materials.

a) The crosslinking process consists in forming a three- dimensional net that confers more resistance to the material, in particular against the action of water. In fact, when water is absorbed within the crosslinked structure, it will not cause it to become immediately deformed, which would otherwise lead, as an early effect, to a loss of mechanical properties, and the structure will not then be destroyed, which would otherwise occur later on due to the solubilization of the material. Some examples envisage enzymatic crosslinking (U.S. Pat. 5,834,232 Cross-Linked Gelatin Gelo and Methods of Making Them, May 1, 1996, Zymogenetics , Inc.), or the use of glutaraldehyde as a crosslinking agent (A. Bigi, G. Codazzi, S. Panzavolta, K. Rubini, N. Roveri, Mechanical and Thermal Properties of Gelatin Films at Different Degrees of Glutaraldehyde Crosslinking, Biomaterials, 2001, vol. 22, pp . 763-768) . b) The addition of known molecules with hydrophobic characteristics inside the structure provides a barrier against water. These molecules, in fact, since they are endowed with natural repulsion to water, limit the entrance of water into the gelatin, thereby preventing, or at least slowing down, the process of absorption thereof. A specific example is given, for example, by the use of thymol, which is a hydrophobic molecule existing in nature within origanum leaves, and which has strong antioxidant and antimicrobial properties (see G. Kavoosi, S.M.M. Dadfar and A.M. Purfard, Mechanical, Physical, Antioxidant and Antimicrobial

Properties of Gelatin Films Incorporated with Thymol for Potential Use as Nano Wound Dressing, Journal of Food Science, 2013, vol. 78, no. 2, pp . 244-250) .

c) As to the last category, reference is made herein to the so- called multilayer technique, wherein, in order to prevent gelatin films from coming into contact with water, an external covering/stratification is provided over the gelatinous material by means of an additional layer of a impermeable/water-repellent plastic. This kind of technique tries to combine the properties of multiple materials in order to make up for their peculiar shortcomings. One example is provided by the combination of PLA/PHB (polylactic acid/poly—b-hydroxybutyrate ) , which have opposite properties (see I. Aumentano, E. Fortunati, N. Burgos, F. Dominici, F. Luci, S. Fiori, A. Jimenez, K. Yoon, J. Ahi, J.M. Kenny, Polymer Letter, 2015, vol. 9, no. 7, pp . 583-596) .

Drawbacks of the prior art

Each one of the above-mentioned solutions still encounters, however, significant difficulties that have limited and/or prevented the applications of materials based on animal gelatin, particularly as far as concerns the packaging of generic solid and non-water-based liquid products. For example, the crosslinking of a material is an irreversible process that creates a three-dimensional structure capable of storing water without solubilizing. The materials thus obtained are called hydrogels (see E. Cald, V.V. Khutoryanskiy, Biomedical Applications of Hydrogels : A Review of Patented and Commercial Products, European Polymer Journal, 2015, vol. 65, pp . 252-267), and have the peculiar capability of considerably increasing their own weight by absorbing water without the gel structure being destroyed. However, the fact that their structure cannot be easily destroyed increases the lifetime of the material and counters the natural disposal thereof. Moreover, when the material has stored sufficient water to become a gel, its possible applications change because its properties are no longer suitable for packaging. In its turn, the use of hydrophobic molecules often refers to organic molecules that are not compatible with the hydrophilic structure of gelatin; this fact makes also very difficult to attain a homogeneous distribution of such hydrophobic molecules throughout the film. In addition, such molecules are normally low-boiling; as a consequence, their natural evaporation process leads to the obtainment of articles which normally release unpleasant odours and which, over time, suffer from gaps in the structure caused by the evaporation process. It is evident that the presence of such gaps leads to a number of criticalities in terms of mechanical properties, making the material more subject to failure.

Finally, also the so-called multilayer method, which may appear as the most promising one because it theoretically overcomes all criticalities, has in its turn some substantial drawbacks, mainly because of the high production costs, and then also because of possible problems of compatibility between the surfaces of the materials being joined, as well as obvious biodegradability problems.

Technical Problem

Therefore, the need is still felt by those skilled in the art for new packaging materials based on animal gelatins which will offer sufficient resistance both in terms of mechanical properties and as a barrier against, in particular, gases (preferably, the oxygen of air) , while being easily and ecologically disposable, for packaging applications, in particular in the field of rigid and/or flexible packaging of alimentary, pharmaceutical and electronic products, detergents or other generic non-water- based liquid products, or in production fields for the production of shopping bags or packaging envelopes, secondary packaging for transport, multi-material packaging (e.g.: cardboard-plastic), laminated multi-materials, expanded materials, 3D printing, containers for different uses obtained by means of the blowmolding technique, or even in fields like label or disposable-glove production. The present invention aims at providing an adequate solution to the above-highlighted technical problem.

Summary of the Invention

As far as is known to the present inventors, the application of a film of gelatin derived/obtained from the skin of fish species, preferably from fish skin, substantially or specifically based on "hydrolized" collagen, in the field of disposable flexible and/or rigid packaging, which can be easily disposed of, and for insulating from oxygen generic products, whether solid or non-water-based liquid products, or in production fields for the production of shopping bags or packaging envelopes, secondary packaging for transport, multi-material packaging (e.g.: cardboard-plastic), laminated multi-materials, expanded materials, 3D printing, containers for different uses obtained by means of the blowmolding technique, or even in fields like label or disposable-glove production, has so far never been taken into consideration or implemented.

The present inventors have now unexpectedly found that the use, within a molding mixture of a material based on fish skin gelatin (substantially or specifically based on hydrolized collagen derived therefrom) as previously described, of at least a suitable effective amount of a molecule capable of slowing down the water absorption process without giving rise to problems like those which may be caused by the addition of hydrophobic molecules, as previously mentioned, can provide an adequate response to the above-highlighted technical problem. The molecule in question is a specific molecule belonging to the family of cyclodextrins , which are carbohydrates derived from wheat fermentation often used in compositions for sports supplements or as thickening agents (see E.M.M. Del Valle, Cyclodextrins and Their Uses: A Review, Process Biochemistry, 2004, vol. 39, no. 9, pp . 1033-1046) . They are characterised by a particular truncated-cone structure in which it is possible to identify a hydrophilic external part and a hydrophobic internal cavity. Cyclodextrins are classified according to the number of glucose units that constitute them, and three main families exist, designated by the letters -, b- and g-, which respectively have 6, 7 and 8 glucose units in their structure. When these constituent units are present in an odd number, the solubility of such molecules decreases and more hydrophobic molecules are obtained (in comparison with those having an even number of glucose units) . Among the above-mentioned cyclodextrins, b-cyclodextrin (with 7 glucose units) has this characteristic and therefore represents a particularly preferred solution to the above-outlined problem. In a particularly preferred embodiment of the present invention, it is the core of the solution proposed by the present invention for packaging applications. With this molecule, the ability of the material to act as a barrier against water (and/or also against gases) has been found to increase considerably, to a greater extent than the other molecules used in the art, while at the same time avoiding the problems caused by the latter. In fact, cyclodextrins do not evaporate at room temperature, are odourless, and do not create a crosslinked structure. Another peculiarity, in comparison with the above-mentioned molecules used in the art, is that the solubility of these molecules, and particularly the one of b-cyclodextrin, increases with the temperature, and thus this characteristic allows it to be completely solubilized, thereby improving the homogeneity of the final material thus obtained; a poor homogeneity was, in fact, one of the criticalities observed in prior systems. All these features have made it possible to create a material that is sufficiently and advantageously highly resistant both in terms of mechanical properties and as a barrier against gases, particularly or specifically oxygen, in addition to being easily and ecologically disposable in an environment- friendly manner, for its advantageous utilization in product packaging applications like those previously listed in this description .

It is therefore an object of the present invention a composition of a gelatin derived from the skin of various fish species, preferably fish skin, and modified/formulated through the addition of at least a suitable amount of a cyclodextrin, for use in the packaging field, as disclosed in the appended independent claim 1.

It is another object of the present invention a film obtained from the above gelatin composition, as disclosed in the appended independent claim.

It is a further object of the present invention the use of the above film in the packaging field, as disclosed in the appended independent claim.

Preferred embodiments of the present invention are disclosed in the appended dependent claims.

The preferred embodiments of the present invention as defined in the following description, are disclosed merely by example and shall not limit by any means the application scope of the present invention, which will become immediately clear to a person skilled in the art.

Brief Description of the Drawings

The present invention will be described in the following, by way of example and without any limitation of the broad scope thereof, by illustrating some preferred embodiments thereof. To this end, to better highlight the potentialities and peculiarities of the present invention, reference will also be made to the annexed Figures 1 - 5, which show the morphological characterization (photographic images taken by means of a scanning electron microscope (SEM) ) of the components used for creating the material composition and of the result of the molding process.

Figure 1 shows the structure (SEM) of a lyophilized b- cyclodextrin of the present invention.

Figure 2 shows the structure (SEM) of the surface of the fish skin gelatin film obtained without the presence of the b-cyclodextrin .

Figure 3 shows the structure (SEM) of the cross-section of the fish skin gelatin film obtained without the presence of the b-cyclodextrin .

Figure 4 shows the structure (SEM) of the surface of the fish skin gelatin film obtained in the presence of the b- cyclodextrin .

Figure 5 shows the structure (SEM) of the cross-section of the fish skin gelatin film obtained in the presence of the b-cyclodextrin .

From the annexed SEM images (Figures 2-5) , it can be noticed that the b-cyclodextrin is properly distributed within the material .

Detailed Description of the Invention

The present invention concerns, therefore, at least the embodiments described in the following points:

[1] A composition based on a gelatin of a fish source (substantially or specifically based on partially or wholly hydrolized collagen obtained from fish skin, in particular deriving from industrial processing scraps), comprising at least : a suitable amount of a gelatin obtained from fish skin derived from industrial processing scraps thereof; and a suitable amount of a cyclodextrin (CD) .

Said composition is also referred to, for simplicity, as a "composition based on modified fish skin gelatin" (i.e. gelatin modified with said cyclodextrin) .

[2] A composition according to point [1], wherein:

said gelatin is selected from any of fish skin gelatins commonly available in the literature and/or on the market; and

the cyclodextrin (hereinafter referred to, for simplicity, as CD) is selected from the group consisting of:

natural CDs: a-CDs, b-CDs, g-CDs;

derived and/or semi-synthetic CDs: alkylated CDs, branched CDs, polymeric CDs, linked CDs, wherein said derived and/or semi-synthetic CDs will be described in detail in the following .

[3] A composition according to points [1] or [2], optionally comprising also a suitable amount of a plasticizer, or of a mixture of plasticizers.

The addition of a suitable amount of a plasticizer, or of a mixture of plasticizers has proven to be particularly useful to subsequently obtain a film having good elasticity, strength and water and gas barrier characteristics, which can advantageously be applied in the packaging field as described herein.

[4] A composition according to any one of the preceding points [1] - [3], further comprising water or an aqueous solution of any non-toxic compound useful for this purpose, in such an amount that pH has a value comprised between 3.6 and 7.60.

[5] The composition according to any one of the preceding points [1] - [4], wherein:

the fish skin gelatin is present in an amount comprised from 20% to 99.9% by weight (w/w) with reference to 100 g of composition; or from 25% to 99.9% w/w; or from 30% to 99.9% w/w; or from 35% to 99.9% w/w; or from 40% to 99.9% w/w; or from 45% to 99.9% w/w; or from 50% to 99.9% w/w;

the cyclodextrin (CD) is present in an amount comprised from 0.01% to 40% by weight (w/w) with reference to 100 g of composition; or from 0.05% to 35% w/w; or from 0.05% to 30% w/w; or from 0.05% to 25% w/w; or from 0.05% to 20% w/w; or from 0.1% to 35% w/w; or from 0.1% to 30% w/w; or from 0.1% to 25% w/w; or from 0.1% to 20% w/w;

the plasticizer is present in an amount comprised from 0% to 60% by weight (w/w) with reference to 100 g of

composition; or from 0% to 55% w/w; or from 0% to 50% w/w; or from 0% to 45% w/w; or from 0% to 40% w/w; or from 0% to 35% w/w; or from 0% to 30% w/w; or from 0% to 25% w/w; or from 0% to 20% w/w; or from 0% to 15% w/w; or from 0% to 10% w/w;

water or the aqueous solution is present in an amount comprised from 0% to 1,000% by weight (w/w) with reference to 100 g of composition; or from 0% to 500%; or from 0% to

400%; or from 0% to 350%; or from 0% to 300%; or from 0% to

250%; or from 0% to 200%; or from 0% to 150%; or from 0% to

100% .

[6] The composition according to any one of the preceding points [1] - [5], wherein:

the fish skin gelatin is present in an amount comprised from 45% to 99.9% w/w with reference to 100 g of composition; the cyclodextrin (CD) is present in an amount comprised from 0.1% to 30.0% w/w with reference to 100 g of composition; the plasticizer is present in an amount comprised from 0% to 50.0% w/w with reference to 100 g of composition;

water is present in an amount comprised from 0% to 1, 000% w/w with reference to 100 g of composition.

[7] Preferably, in the composition according to any one of the preceding points [ 1 ]— [ 6 ] :

the fish skin gelatin is present in an amount comprised from

55% to 97% w/w with reference to 100 g of composition;

the cyclodextrin (CD) is present in an amount comprised from

2% to 25% w/w with reference to 100 g of composition;

the plasticizer is present in an amount comprised from 1% to

40.0% w/w with reference to 100 g of composition;

water is present in an amount comprised from 0% to 1, 000% w/w with reference to 100 g of composition.

[8] Even more preferably, in said composition:

the fish skin gelatin is present in an amount comprised from

65% to 92% w/w with reference to 100 g of composition;

the cyclodextrin (CD) is present in an amount comprised from

3% to 20% w/w with reference to 100 g of composition;

the plasticizer is present in an amount comprised from 5% to

30.0% w/w with reference to 100 g of composition;

water is present in an amount comprised from 0% to 1, 000% w/w with reference to 100 g of composition.

[9] In a particularly preferred embodiment of the present invention :

gelatin is selected from a gelatin extracted from the skin of various fish species and is characterized, by way of example, by the following properties: the cyclodextrin (CD) is a natural cyclodextrin selected from a b-cyclodextrin commonly available on the market, or also from all synthetic products derived from b- cyclodextrin;

the plasticizer, if present, is selected from any suitable commercial non-toxic plasticizer, easily available from various plasticizer producers, such as, for example, glycerol (glycerine); and/or water-soluble polyols, e.g., sorbitol, in particular selected from the commercial ones, e.g., those obtainable also from renewable sources; e.g., polyethylene glycols having various molecular weights, which permit the fabrication of a rigid packaging, and/or polyvinyl alcohols with variable molecular weight, which permit the fabrication of materials having better performance; and/or suitable mixtures thereof.

[10] In a particularly preferred, but by no means limiting, embodiment of the present invention, gelatin is the commercial gelatin extracted from fish skin known under the commercial name Fish Skin Gelatine GLF/F 22, 08 mesh, produced and marketed by Company LAPI GELATINE (Via Lucchese 158, Empoli (FI), Italy) . For sake of completeness, the contents of a certificate of analysis thereof are shown below, provided by the Chemistry and Pharmaceutics Department of the University of Sassari (IT) . LAPI GELATINE

Certificate of Analysis

Date: 04/10/2016

Sample no. 6086: g 500 - Fish Skin Gelatine GLF/F 22 -

08 mesh

Pharmagrade Gelatine According to Eu.Ph. ed. 8.3

[11] In a further and particularly preferred embodiment of the invention, the composition as described in any one of the preceding points is in the form of a film.

Accordingly, it is a particularly preferred embodiment of the invention also a film obtained/constituted by a composition according to any one of the preceding points. In particular, said film can advantageously be used in a broad range of applications in the packaging field, as described in the present description.

In general, said film of the present invention has a thickness ranging from 1 micron to 5 mm; preferably, from 2 micron to 4 mm; preferably, from 3 micron to 3 mm; preferably, from 4 micron to 2 mm; preferably, from 5 micron to 1 mm. In any case, depending on the specific requirements and the equipment used for making the film, it is possible to obtain a film having any thickness, as deemed appropriate for the intended application. It is not necessary, therefore, to provide herein further possible thicknesses obtainable from the modified gelatin of the present invention, which will anyway be easily obtainable by a person skilled in the art, and hence will fall within the scope of the present invention .

[12] A further embodiment consists of a process for producing a film according to the preceding point [11], wherein said process can be appropriately selected by a person skilled in the art from any traditional process for the production of a film utilizing traditional techniques for processing plastic materials, such as, for example, casting, blowmolding, extrusion, rolling, compression molding, injection molding, rotational molding and thermoforming; preferably, casting and/or rolling. As a consequence, it is not necessary to illustrate in detail herein any of such known processes for producing plastic films .

[13] In view of what above described and in the appended claims, it is a further object of the present invention the use of a film according to point [11] in packaging applications: in particular, flexible and/or rigid packaging of alimentary, pharmaceutical and electronic products, detergents and/or other generic non-water-based liquid products; or in production fields for the production of shopping bags or packaging envelopes, secondary packaging for transport, multi-material packaging, cardboard-plastic; laminated multi-materials, expanded materials, 3D printing; containers for different uses obtained by means of the blowmolding technique, or even in fields like label or disposable-glove production.

[14] Fish skin gelatins derived from industrial fish processing scraps are particularly preferred for the purposes of the present invention. Fish skin gelatins for alimentary or pharmaceutical applications are normally obtained from fish processing scraps, which constitute 60% by weight of the source product. This percentage is representative of the sum of the weights of the skin (optionally, also of bones, scales and heads, depending on the desired type of product) of the processed product. Many production processes separate such scraps for the correct disposal thereof. Collagen, which is the constituent protein of these animals, is mainly produced from fish processing scraps, and is then transformed into gelatin by means of a special acid-base hydrolytic and heating treatment. The conversion of collagen into gelatin will be dependent on temperature, time and pH, in addition to the pre-treatments carried out on the raw material, such as, for example, drying or smoking. The most important difference between collagen and gelatin is that collagen is insoluble in water, while gelatin is soluble in water.

In general, the amount of collagen or gelatin obtained and the characteristics thereof depend on the raw material employed and also on the chosen fish species and its place of origin. The differences existing between one species and another can be essentially attributed to a different amino acid composition of the final molecule extracted and to the mean molecular weight of the latter. However, for the purposes of the present invention, the present inventors have come to the conclusion (in view of a number of preliminary experiments, not shown herein) that the same effect can be observed when using gelatins from different sources according to the present invention. Therefore, the scope of the present invention embraces all of the main sources of collagen (at least partially or wholly hydrolized) and of fish skin gelatin which can be found in the literature or which are commercially available. Procedures for the extraction of gelatin from fish skin have been described for different cold-water fish species, e.g. white cod, Atlantic salmon, haddock and Alaska hake; tropical or sub-tropical species, e.g. black or red tilapia, Nile perch, channel catfish, yellowfin tuna, sin croaker, shortfin scad, carp or grass carp; flat species, e.g. megrim, Dover sole; (see, for example, Functional and bioactive properties of collagen and gelatin from alternative sources: A review, M.C.Gdmez- Guillen, B.Gimenez, M . E . Ldpez-Caballero ; and M.P.Montero, Food Hydrocolloids, Volume 25, Issue 8, December 2011, pp . 1813-1827) . The number of fish or marine species studied for gelatin extraction is continually growing. For example, gelatins have been extracted from the skin of: bigeye snapper (Priacanthus tayenus and Priacanthus macracanthus ) (Benjakul, Oungbho, Visessanguan, Thiansilakul , & Roytrakul, 2009) , lunar-tailed bigeye (Priacanthus hamrur) (Binsi, Shamasundar, Dileep, Badii, & Howell, 2009) , greater lizardfish (Saurida tumbil) (Taheri, Abedian Kenari, Gildberg, & Behnam, 2009) , grouper (Serranidae sp) (Rahman & Al-Mahrouqi, 2009) , Hoki (Macruronus novaezelandiae ) (Mohtar, Perera, & Quek, 2010), giant catfish ( Pangasianodon gigas) ( Jongjareonrak et al . , 2010) . All these products can advantageously be used for the purposes of the present invention. In a particularly preferred embodiment of the present invention (which nevertheless is not intended to limit the same by any means), the fish skin gelatin is a known commercial gelatin extracted from fish skin named Fish Skin Gelatine GLF/F 22, 08 mesh, produced and marketed by

Company LAPI GELATINE (Via Lucchese 158, Empoli (FI), Italy), as broadly discussed above.

[15] Coverage of all derivatives of the family of cyclodextrins (CD) falls within the scope of the present invention, in that, even though not expressly exemplified and applied in this description, they may lead to the same effect when appropriately combined with fish skin gelatin on the basis of the common knowledge of those skilled in the art. In fact, a person skilled in the art will encounter no particular difficulty in selecting, based on his own experience, those CDs which are most suitable for a specific application .

As aforementioned, CDs are generally classified into:

- natural CDs;

- derived or semi-synthetic CDs, which in turn comprise: alkylated CDs;

branched CDs;

polymeric CDs;

- linked CDs.

Natural CDs are those directly derived from the previously described enzymatic hydrolysis (see E.M.M. Del Valle, Cyclodextrins and Their Uses: A Review, Process Biochemistry, 2004, vol. 39, no. 9, pp . 1033-1046), i.e. a- CDs, b-CDs, g-CDs, and the essential differences among these three species are listed in the following table:

Derived or semi-synthetic CDs are obtained by substitution of the H atoms of the OHs that are present on each glucose unit .

Alkylated CDs have better solubility in H ₂ 0, even when the substituent groups have a lipophilic character (methyl and hydroxy-propyl) .

Branched CDs have a solubility > 50g/100mL, have no hemolytic properties, but have a lower complexing power (glucose and diglucosyl- b-CD and maltosyl- and dimaltosyl- b-CD) .

Polymeric CDs known in the art are used as excipients for prolonged-release forms because they are poorly soluble. Linked CDs are dimers linked to a suitable chain. They have been designed to allow the inclusion of large molecules.

The combination of these two elements of the present invention is the core of the present invention as regards the use of the films obtained therefrom for packaging production, as previously described. In substance, the present invention is based on the modifications made to the barrier properties of the gelatin film, which modifications are due to the presence of a suitable cyclodextrin. Determining the barrier properties of a polymer is essential in order to be able to estimate and foresee the shelf-life of the packaged product and its durability over time. The specific barrier requisite for a packaging system depends on the final use thereof, e.g. on the characteristics of the food for which the application is intended. Generally, the traditional plastic materials used for packaging purposes are relatively permeable to small molecules such as gases, water vapor, organic vapors and liquids, and have very variable values as concerns the gas-solid transport properties, ranging from excellent to poor. Of course, good barrier properties are very important for food packaging applications. In fact, water vapor and oxygen (air) are two of the main permeants taken into account in packaging applications, since they may pass from the inside or outside environment through the package walls, thereby causing possible negative variations in the quality and shelf-life of the product. By way of comparative example, the most important barrier properties of the polymeric films typically employed are shown in following Table.

Experimental Section

The following experimental section describes some of the characteristic aspects of the present invention, without however limiting the broad potential use thereof.

Example

In a preferred embodiment, 16 g of gelatin obtained from fish skin derived from processing scraps of various fish species (by way of non-limiting example, the above-described commercial product available from company LAPI GELATINE may be used) are dissolved under magnetic stirring into 200 ml of distilled water or in an aqueous solution as previously described in this description at a temperature of 80 °C for 30 minutes, thereby promoting complete solubilization thereof. The temperature is then lowered to 45 °C, followed by the addition of, while keeping the solution under stirring, 5.3 g of a solution of glycerin in water or aqueous solution as specified above with 87% by weight of glycerin (in another embodiment, 5.3 g of pure glycerin may be added as an alternative) and 5 ml of an aqueous solution of b- cyclodextrin, prepared by solubilizing 0.48 g of lyophilized solid b-cyclodextrin into 5 ml of distilled water. All is maintained in these conditions, under stirring, for 10 minutes until complete solubilization of the added components is attained. Glycerin acts as a plasticizer, making it possible to obtain a gelatin film after water evaporation. The obtained solutions are very viscous, and therefore during the stirring process they tend to incorporate much air, which during the film evaporation process may create gaps in the structure. Therefore, after the previous working step the mixture is maintained under vacuum at 200 mbar for 30 minutes. At this point, 20 ml of the solution are poured into a flat mold and left to rest at room temperature (at 25 - 28°C) for 24 hours, checking that the surface of the liquid is perfectly flat. After this time has elapsed, the film is removed from the mold and maintained at a temperature of 50°C for one hour, thus completing the evaporation of the water solvent.

At the end of the process, the following percentages (w/w) of every single component in 100 g of plastic material thus obtained have been calculated:

As can be inferred from the following characterization of the material achieved by using as little as 2.2% w/w of b- cyclodextrin, the water vapor barrier increases by more than 50%. Much reasonably, further increases of this molecule may be expected to bring an additional increase of this property without affecting the transparency of the material. The characterization shown below has been carried out in compliance with the current UNI EN ISO standards of the European Community.

Characterization of the obtained materials:

Thermal degradation characterization (TGA, Termal Gravimetric Analysis) of the fish skin gelatin films in the presence or absence of b-cyclodextrin .

Table 1

Thermal characterization under nitrogen atmosphere (DSC, Differential Scanning Calorimetry) of the fish skin gelatin films in the presence or absence of b-cyclodextrin .

The following table shows the glass transition temperature (Tg) values of the prepared gelatin films.

Table 2

Thermal characterization under oxygen atmosphere (DSC, Differential Scanning Calorimetry) of the fish skin gelatin films in the presence or absence of b-cyclodextrin .

Table 3

Dynamic mechanical analysis (DMA) of the fish skin gelatin films in the presence or absence of b-cyclodextrin . Table 4

Oxygen permeability values, measured by means of a Oxygen Permeation Analyzer 8500 (Systech Industries, Metrotec S. A. , Spain) , of the fish skin gelatin films in the presence or absence of b-cyclodextrin .

Table 5

Water vapor permeability values, measured in compliance with ASTM E96/E96 M-05 standard, of the fish skin gelatin films in the presence or absence of b-cyclodextrin .

Table 6

Measured values of water contact angle with a surface of the fish skin gelatin film in the presence or absence of b- cyclodextrin .

Table 7

Measured values of the thickness of the fish skin gelatin films, in the presence or absence of b-cyclodextrin, obtained by using the casting method previously described in the experimental section.

Table 8

Transparency (UV-vis analysis) of the fish skin gelatin films in the presence or absence of b-cyclodextrin .

As far as this characteristic is concerned, the presence of the cyclodextrin has not altered the transmittance value therof to a significant extent, thus further confirming the advantages (already shown above) of the film of the present invention for use in the packaging field as previously described .

In view of all the above, it can be clearly inferred that the compositions of the present invention, as well as the films obtained therefrom, have completely unexpectedly proven to be particularly advantageous over those, even apparently similar, described in the prior art, like the one previously mentioned, from all points of view as regards their possible use in the packaging field.

Industrial Applicabili ty of the Invention

The fish skin gelatin modified through the addition of at least one cyclodextrin, and optionally a plasticizer, and optionally water or an aqueous solution as previously described, of the present invention has turned out to be very useful for preparing films which can advantageously be used in the packaging field, in particular for rigid and/or flexible packaging of alimentary, pharmaceutical and electronic products, detergents or other generic non-water- based liquid products, or in production field for the production of shopping bags or packaging envelopes, secondary packaging for transport, multi-material packaging (e.g.: cardboard-plastic), laminated multi-materials, expanded materials, 3D printing, containers for different uses obtained by means of the blowmolding technique, or even in fields like label production. Said films have proven to be much better than the analogous or similar ones described and/or prepared by applying the teachings of the prior art.