Triple layer film

Abstract

The present invention relates to a film comprising: a first layer comprising: at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran, and one or more organic plasticisers; a second layer comprising: at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar, and one or more organic plasticisers; and a third layer, wherein the film contains less than 1 wt% of cations of calcium; to a process for the preparation of the film, to uses of the film and to methods of using the film.

Description

[0001] Triple Layer Film

[0002] FIELD OF THE INVENTION

[0003] This invention relates to the field of heat sealable, water dispersible and biodegradable films comprising polymers of natural algae and plant or fungi origin. The inventive films combine the properties of different polymers across at least three different layers to enable the creation of such films. The inventive films can be used for packing products, such as powder and liquid products, in sachets using current heat sealing equipment and at commercially viable production rates. In particular, the inventive films can be used in Vertical-Form-Fill-Seal (VFFS) or Horizontal-Form-Fill- Seal (HFFS) packaging equipment as well as in pod forming and filling equipment (such as the Hydroforma pod maker from Mespack) without requiring significant equipment modification. The inventive films predominantly use natural materials that are readily available, of low price and that have not required extensive or expensive chemical modifications.

[0004] BACKGROUND

[0005] Packaging materials made using renewable materials are of increasing interest and importance as environmental pressures dictate a move away from oil-based feedstock. Such packaging materials include films which are especially useful for wrapping and / or encapsulating products. Examples of products using films for packaging include sachets, capsules, pods, pouches, packets and bags. It is highly preferred if the packaging material, as well as being sourced from renewable materials, is highly biodegradable so as to minimise the problems of waste disposal. Typically, products made from renewable, natural feedstock, are highly biodegradable provided that they have not been substantially chemically modified. Chemical modification can dramatically lower the biodegradability profile.

[0006] However, many synthetic polymer films are still widely used due to their high performance, particularly their water dispersibility and mechanical properties, as well as low cost. For example, water-dispersible films made solely from polyvinyl alcohol are widely available and widely used - for example in packaging of detergents. Often, they are marketed as being environmentally friendly. Examples include Monosol M-8630 from Monosol (now Kuraray) and Solublon® from Aicello, Japan. Typically, such films are marketed as soluble but actually have poor biodegradability in marine biodegradation tests and can accumulate in the environment. Many biopolymers, or materials of natural origin, can be used to make packaging films. Widely used examples of biopolymer films include starches and cellulose-based films. Starches are especially widely used due to their low cost and ready availability. Typically, the starches are chemically modified to improve their processability and functionality. One example of a modified starch is hydroxypropylated amylose starch. Other substituents may be hydroxyethyl or hydroxybutyl to form hydroxyether substitutions, or anhydrides such as maleic phthalic or octenyl succinic anhydride can be used to produce starch ester derivatives. Starch films typically have high tensile strengths at moderate humidity (such as between 30% and 50% relative humidity at 20 °C) but typically become much weaker at higher humidity unless they have been highly chemically modified. In particular, many starch films are very susceptible during storage at low temperatures, as starches are prone to retrogradation. Starch films are also slow to solubilise in water and not well suited to releasing the packaged product in water. Examples of starch-based films are those sold by Plantic Technologies Ltd (now part of Kuraray).

[0007] Cellulose-based polymers and materials can also form films and are also widely used. Commonly, cellulose films are made from so-called “regenerated” cellulose wherein cellulose fibers are dissolved in carbon disulphide under alkaline conditions to form viscose. The viscose is then contacted with an acidic solution to “regenerate” the cellulose. Such processes are resource and energy intensive, and the resulting cellulose films are not water-soluble or water-dispersible at all, and they do not heat seal. Regenerated cellulose is used in NatureFlex films, which are cellulose-based compostable packaging films sold by Futamura. Other cellulose-materials include hyproxypropyl methyl cellulose (HPMC) and carboxymethyl cellulose (CMC). HPMC films have long been used in the medical field as a coating for tablets. However, HPMC itself requires significant effort to synthesise and thus is relatively expensive. It is not fully biodegradable due to the high level of synthetic modification.

[0008] The use of biopolymers to make films and coatings is increasingly widespread and much effort continues to be put into using naturally sourced, renewable materials as replacements for non-renewable feedstock such as petroleum. The art is large and widespread and examples given below are for illustrative purposes only.

[0009] Many naturally-derived biopolymers are being used including plant-derived, algae-derived, fungi-derived and animal-derived materials. Examples of animal-derived materials used to make films and coating include collagen, gelatine, chitosan, shellac and casein. Examples of plant-derived materials used include starch, celluloses, proteins including pea, soy, corn and potato, pectin and so on. Examples of algae- derived materials include alginates, carrageenan, furcellaran, and other gums. An example of a fungi-derived material is pullulan. The reasons for using biopolymers in these applications range from wanting to use renewable feedstock, to having more biodegradable materials, to using more biocompatible materials for medical applications and even to provide edible packaging. There is a need to increase the use of naturally-derived biopolymers for environmental reasons.

[0010] Algae-derived polysaccharides can be made into robust films. However, such films do not heat seal easily.

[0011] Plant-derived polysaccharides can be made into robust films. However, such films do not disperse in water easily.

[0012] Biopolymers are complex materials and often harder to process and handle than synthetic polymers. Typically, they are susceptible to moisture and lose strength in high humidity environments. This susceptibility of biopolymers to moisture is typically an inherent feature due to their natural sources and is the major limitation to their more widespread use. Other issues include poorer thermoplastic properties including heat sealing of biopolymer films. Rapid and effective heat sealing without thermal damage is critical for industrial production of sachets and many other package forms.

[0013] Polyhydroxyalkanoates (PHAs) are increasingly used due to their good thermoplastic properties. PHAs are natural biopolymers sourced from microbial fermentation but are slow to biodegrade and are insoluble.

[0014] An example of an animal-derived biopolymer is casein. EP3728477A1 describes a thermoplastic casein composition and packaging films made from thermoplastic casein. US9662400B2 describes chitosan films useful for medical applications. US6448378B2 describes soluble collagen films which are used to deliver drug treatments. A large-scale application for many edible films including collagen, alginate and protein-based films (amongst others) is for sausage casings. Sausage casings do not need to be heat sealed. US3408916 describes collagen films used for sausage casings. US6730340B1 describes a plant-based biopolymer blend for sausage casings based on mixtures of carrageenan and gellan gum.

[0015] US10092925B2 and JP6010068B2 describe production process for making alginate films. No mention is made of heat sealing. JPH0530891A describes use of a blend of alginate and other polysaccharides, principally pullulan. It states that pure alginate films do not heat seal. Blending high levels of pullulan with alginate results in a film that can be sealed but is non-soluble. Pullulan is expensive for large-scale use as the majority component of a film.

[0016] Starch is cheap and can be chemically modified to improve its properties. US5498662 describes gas barrier films comprising a blend of poly(meth)acrylic acid and starch. Thermoplastic starches are available under the MATER-BI trade name supplied by Novamont. US20040242732A1, EP2496644B1 and W02011080623A2 describe a biodegradable polymer composition based on chemically modified starch plus synthetic polymers. These materials can be used to form films.

[0017] Cellulose derivatives, and especially cellulose ethers such as hydroxypropyl methyl cellulose, are used to make films, commonly for medical applications. EP1045000B1 describes an ingestible HPMC film. Such materials, whilst often safe to ingest, require high levels of synthetic modification. HPMC is often used for drug coatings due to its selective pH solubility.

[0018] The use of laminated films to overcome some of the limitations of a single biopolymer is known. EP2013290B1 describes a silk protein laminate film where the silk protein is laminated with another layer which could be either a different protein, such as collagen, or a synthetic polymer. There is no mention of heat sealing.

[0019] JP2010136685A describes a laminated film comprising a cationic biopolymer, typically chitosan, and an anionic biopolymer, typically gelatine. The resulting film is insoluble. The film can be heat sealed but no details are given.

[0020] EP3721721A1 describes an edible, multilayer food coating comprising three layers of different hydrocolloid substances. In each layer a colloidal dispersion reacts with a divalent cation forming solid insoluble layers. Each layer can be successively built around the food product in turn. Such a multilayer does not have the robust physical strength properties needed to be made into sachets using current heat sealing equipment and at commercially viable production rates. Such a film, where biopolymers in the layers are cross-linked with divalent cations, are highly insoluble and not water dispersible.

[0021] Accordingly, there exists a need to develop films that are both water dispersible and heat sealable whilst having sufficiently robust mechanical properties for them to be used as packaging films, including being handled in a manufacturing process and able to survive transportation and storage at low temperatures. Additionally where there is a benefit to film performance by the use of synthetic polymers, there is a need to minimise their use so that such products typically have an improved environmental profile compared to equivalent products that use only synthetic materials.

[0022] SUMMARY OF THE INVENTION

[0023] Viewed from a first aspect, the present invention provides a film comprising: a first layer comprising: at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran; and one or more organic plasticisers; a second layer comprising: at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar; and one or more organic plasticisers; and a third layer, wherein the film contains less than 1 wt% of cations of calcium.

[0024] Viewed from a further aspect, the present invention provides a process for preparing a film as hereinbefore described, comprising the steps of:

[0025] (i) providing a first layer comprising at least one red algae- or brown algae- derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran, and one or more organic plasticisers;

[0026] (ii) providing a second layer comprising at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar, and one or more organic plasticisers;

[0027] (iii) providing a third layer; and

[0028] (iv) forming said first layer, said second layer and said third layer into said film, wherein the film contains less than 1 wt% of cations of calcium.

[0029] Viewed from a further aspect, the present invention provides a film obtained by or obtainable by a process as hereinbefore described.

[0030] Viewed from a further aspect, the present invention provides a product enclosed by a film as hereinbefore described.

[0031] Viewed from a further aspect, the present invention provides a method of enclosing a product, comprising the steps of:

[0032] (i) wrapping the product in a film as hereinbefore described; and

[0033] (ii) heat sealing the film around the product to form a sachet.

[0034] Viewed from a further aspect, the present invention the use of a film as hereinbefore described to enclose a product and / or to prepare a sachet.

[0035] Viewed from a further aspect, the present invention provides a sachet prepared by a method as hereinbefore described. Viewed from a further aspect, the present invention provides a method of releasing a product enclosed in a film as hereinbefore described, comprising the steps of:

[0036] (i) placing the enclosed product in water; and

[0037] (ii) allowing the film to disperse, thereby releasing the product.

[0038] DETAILED DESCRIPTION OF THE INVENTION Definitions

[0039] As used herein, the phrase “substantially free of cations of calcium” means that the layer or film in question contains less than 1 wt% of cations of calcium (i.e. Ca2+), preferably less than 0.5 wt%, more preferably less than 0.1 wt%, more preferably less than 0.05 wt%, more preferably less than 0.01 wt%, more preferably less than 0.005 wt%, more preferably less than 0.001 wt%, more preferably less than 0.0005 wt%, most preferably 0 wt% based upon the total weight of the film, as measured by atomic absorption spectrophotometry (AAS). AAS detects elements in samples through the application of characteristic wavelengths of electromagnetic radiation from a light source. Individual elements will absorb wavelengths differently, and these absorbances are measured against standards. Preferably Flame atomic absorption spectrometry (FASS) is used to analyse the elements calcium, magnesium, strontium and zinc. A typical sample preparation procedure for solid samples involves digestion with a concentrated acid; for example, HNO3, HCI, or H2SO4. Other sample preparation methods, including microwave and high-pressure digestion, are also used to break up samples. After dilution of the digested solutions, samples can be directly injected into the spectrophotometer. Preferably, the films of the present invention do not contain any cations of divalent metals selected from calcium, magnesium, strontium, and zinc (i.e. they contain 0 wt% cations of divalent metals selected from calcium, magnesium, strontium, and zinc based upon the total weight of the film). As would be understood by a skilled person, the films of the present invention may, however, contain contaminant levels of cations of divalent metals selected from calcium, magnesium, strontium, and zinc. This may occur, for example, if the process used to prepare the films involves the use of hard water, which contains around 200 mg / l calcium carbonate and around 200 mg / l magnesium carbonate.

[0040] As used herein, the phrase “heat-sealable compound” refers to a compound that when incorporated into a film, the film can partially melt and become tacky at the surface at an elevated temperature, and therefore when in contact with a surface of another film or another surface of the said film, can form a seal which is permanent when the film is cooled back to room temperature. Pressure can also be used to assist in the formation of the seal. The cooled seal formed can be broken with substantial force or by dispersion or dissolution of the film. The effect of a heat-sealable compound can be evaluated by measuring the onset melting temperature of films containing the heat-sealable compound according to the methods herein described, for example using Differential Scanning Calorimetry (DSC).

[0041] As used herein, the phrase “dispersibility-enhancing compound” refers to a compound that when incorporated into a film can assist with the break-up of the film into small fragments when the film is added to water and agitated. The effect of a dispersibility-enhancing compound can be evaluated by measuring the dispersion in water of films containing the dispersibility-enhancing compound according to the methods herein described.

[0042] As used herein, the phrase “strengthening compound” refers to a compound that when incorporated into a film improves the strength of the film making it more robust in handling or in packaging equipment. The effect of a strengthening compound can be evaluated by measuring the tensile strength of films containing the strengthening compound according to the methods herein described.

[0043] As used herein, the phrase “inner layer” refers to the layer of the film that, in use, has a surface that is primarily in contact with the product to be enclosed and not the external environment. Typically, the inner layer comprises a heat-sealable compound.

[0044] As used herein, the phrase “outer layer” refers to the layer of the film that, in use, has a surface that is primarily in contact with the external environment and not the product being enclosed.

[0045] As used herein, the phrase “middle layer” refers to the layer or layers of the film that are located between the inner layer and the outer layer. As would be understood by a skilled person, the films of the present invention may contain one middle layer, or more than one middle layer.

[0046] As used herein, the phrase “outer surface” refers to the surface of the film that, in use, will primarily be in contact with the external environment and not the product being enclosed.

[0047] As used herein, the phrase “inner surface” refers to the surface of the film that, in use, will primarily be in contact with the product to be enclosed and not the external environment.

[0048] As used herein, the phrase “fin seal” or “fold-over seam” refers to the sealing arrangement where at least a portion of two inner surfaces of film are sealed together. As would be understood by a skilled person, a fin seal can be prepared by folding over a single piece of film, or sealing together two separate films. As used herein, the phrase “lap seal” or “overlap seam” refers to the sealing arrangement where at least a portion of the outer surface of film is sealed together with at least a portion of the inner surface of film. As would be understood by a skilled person, a lap seal can be prepared by folding over a single piece of film, or sealing together two separate films.

[0049] As used herein, the phrase “ambient temperature” or “room temperature” refers to a temperature of approximately 20 to 25°C.

[0050] As used herein, the phrase “water soluble film” or “water soluble sachet” refers to a film or sachet that dissolves in water at a temperature of 20 to 25 °C.

[0051] As used herein, the phrase “water dispersible film” or “water dispersible sachet” refers to a film or sachet that disperses in water and achieves a result of “high”, “very high” or “maximum” when tested according to the following method: the water dispersibility of the films is assessed using 0.75g samples of each of the final films, conditioned at 55% relative humidity and a temperature of 20°C. Samples are mixed at room temperature using an overhead stirrer at 300 rpm in 300 ml of freshly boiled reverse osmosis water (i.e. having a temperature range 75°C to 90°C) in a 600 ml beaker for 3 minutes. The end mix is visually inspected for any remaining particles, and their size used to judge water dispersibility on the following scale: Very low - majority of particles >30mm; Low - majority of particles ~20-30mm; Average - majority of particles ~10-20mm; High - majority of particles ~1-10mm; Very high - majority of particles <1mm; Maximum - no visible particles.

[0052] As used herein, the phrase “water activity” refers to the ratio at equilibrium between the vapour pressure of water over a sample and the vapour pressure of pure water under the same conditions (e.g. temperature). It can be referred to as “free water” indicating that it is unbound and available. Water activity can be measured easily using commercially available devices, for example the HygroPalm23-AW from Rotronic.

[0053] As used herein, the phrase “red algae-derived polysaccharides” refers to polysaccharides obtained from red macroalgae or red microalgae, be that via an extraction process performed on naturally grown or cultivated red macroalgae or red microalgae, or via synthetic processes to yield the same materials that would be present in naturally grown or cultivated red macroalgae or red microalgae.

[0054] As used herein, the phrase “red seaweed-derived polysaccharides” (or “red macroalgae-derived polysaccharides”) refers to polysaccharides obtained from red macroalgae, be that via an extraction process performed on naturally grown or cultivated red macroalgae, or via synthetic processes to yield the same materials that would be present in naturally grown or cultivated red macroalgae. As used herein, the phrase “brown algae-derived polysaccharides” refers to polysaccharides obtained from brown macroalgae or brown microalgae, be that via an extraction process performed on naturally grown or cultivated brown macroalgae or brown microalgae, or via synthetic processes to yield the same materials that would be present in naturally grown or cultivated brown macroalgae or brown microalgae.

[0055] As used herein, the phrase “brown seaweed-derived polysaccharides” (or “brown macroalgae-derived polysaccharides”) refers to polysaccharides obtained from brown macroalgae, be that via an extraction process performed on naturally grown or cultivated red macroalgae, or via synthetic processes to yield the same materials that would be present in naturally grown or cultivated brown macroalgae.

[0056] As used herein, the phrase “alkali-treated plant-derived protein” refers to a plant-derived protein that has been mixed with a base or alkali, so that when the resulting plant-derived protein is mixed into water the pH of the dispersion is greater than 7, preferably greater than 8, more preferably greater than 9, even more preferably greater than 10. This process generally results in a plant-derived protein which is more easily dispersed in water. One way of preparing an alkali-treated plant-derived protein is described in Example 10.

[0057] It is preferable if non-traditional sources of biopolymers can be used whenever possible when sourcing feedstock for the inventive packaging films. Such non- traditional feedstock can be combined with traditional feedstock. “Traditional” relates to biopolymers typically used as human feedstuffs, for example starches. Particularly preferred biopolymers for the first layer of the inventive films are red algae- and brown algae-derived polysaccharides which do not directly compete with food crops and do not require valuable farmland.

[0058] The suitability of the inventive films for commercial use does not just depend on their positive environmental profile. The films have to be processable in order to effectively enclose and protect a product. They have to be robust throughout the multiple environments experienced, including manufacture, storage and final use. They have to meet multiple different requirements, such as elongation and tensile strength. They must also be heat sealable to form an enclosed and sealed packaging layer around a product. As used herein, such packaging is referred to as a “sachet” however this term includes items commonly described as pods, capsules, pouches, packets and bags etc.

[0059] In heat sealing, two films are pressed together and subjected to heat for a specified amount of time. The application of heat causes the diffusion and migration of polymer chains at the interface from film to film causing the formation of a bond as the seal is cooled. Not all polymer materials will heat seal as the mechanism depends on the behaviour of polymer chains at the interface. If these chains do not easily move or migrate, then the films will not seal. The ease of heat sealing is a complex interaction of polymer type, level of crystallinity, plasticisation, temperature and time.

[0060] Without wishing to be bound by theory, the poor heat-sealing behaviour of typical red algae- and brown algae-derived films is believed to result from the more compact structures that such materials seem to form when subjected to heat. This effect has been reported in the art and is used in some film making processes where heat treatments are used to make denser and less-permeable films. Production of red algae- and brown algae-derived films very often involves the application of heat to remove water. Heat sealing by definition requires heat to be applied. Thus, such materials would seem to be inherently poorly suited to heat sealing applications.

[0061] One established route for sealing biopolymer films is to use an adhesive to glue the films together. This can be combined with the application of heat and pressure to ensure good sealing. Such an approach is viable for certain types of equipment, such as the Hydroforma pod maker from Mespack, as the design of the drum allows the application of an adhesive layer on to one or both films. Nonetheless, adhesives come with their own draw backs such as the risk of contamination of the enclosed material or contamination of the adhesive by the enclosed product, particularly when a liquid or powder reduces seal robustness.

[0062] Many packing companies, however, use Vertical-Form-Fill Seal (VFFS) or Horizontal-Form-Fill Seal (HFFS) technology to make sachets. The films of the present invention are suitable for use in both.

[0063] In the VFFS process, film is drawn through the packing equipment vertically and folded together and sealed to form the sachet. Typically, a strip of film is folded around the filling head and sealed to form a cylinder or tube which is then sealed at the base, filled with the contents through the filling head and the top is then sealed. This approach can be used for both powders and liquids. The need to “pull” film through the equipment means that the film needs to have a minimum strength. The film cannot stretch too much otherwise it becomes very hard to control the correct positioning and alignment of the film. The film cannot be sticky to the touch as otherwise the friction on the film as the film is pulled through the equipment is too high. This means that spraying or applying a coating to one surface as the film strip is pulled through the packing line is just not practical.

[0064] HFFS equipment is very similar to VFFS equipment but the film travels in a horizontal direction. It is particularly useful to pack solid type commodities such as chocolate bars, etc. The films of the present invention are also suitable for use in pod-making. In typical pod-making equipment, as in the Hydroforma pod maker by Mespack, a sheet of film is drawn down into a mold by the application of vacuum to form a cavity, material, such as a liquid detergent, is placed in the cavity and a second sheet of film is used to seal the cavity. The sealing can be by heat sealing or by solvent / adhesive sealing or combinations thereof.

[0065] The inventors have discovered that a triple layer film comprising a red algae- or brown algae-derived polysaccharide layer, a layer comprising at least one material selected from plant-derived polysaccharides, fungi-derived polysaccharides and agar, and a third layer, wherein the film is substantially free of cations of divalent metals selected from calcium, magnesium, strontium, and zinc, can overcome the various challenges highlighted above, based on selection of the materials, their position in the film and thicknesses of the layers. Such inventive films have good physical properties, such as tensile strength, over a wide range of conditions. They can be made predominantly from natural materials that do not require chemical modification or crosslinking and are of low cost and readily available. They can therefore have high dispersibility in water and have a very high biodegradability. Careful selection of the materials in each layer, their position in the film and the thicknesses of the layers means they can be heat sealed under industrially relevant conditions to package products that can be readily released in water.

[0066] Any film that needs to seal a product to enclose it needs to be sealable within a short period of time for any production to be industrially viable. The design of a packing line mean means that the production rate is directly related to the time taken to perform the sealing. If it takes 5 seconds to perform the sealing operation, then an individual line can at best only make 12 sachets a minute. This rate is far too low to be economically viable. Sealing times need to be 1 second or less, and preferably less than 0.5 seconds, for any production process to be economically viable for most products. Hence, the practical definition of heat sealability needs to include that, as well as being able to form robust seals, this needs to be achievable in 1 second or less and preferably in less than 0.5 seconds.

[0067] Heat sealing depends on the temperature at the interface of the two films being sealed to be high enough to start to melt the material at the interface so it starts to migrate and inter-penetrate. The temperature at the interface of the two films depends on the following variables.

[0068] (i) The temperature of the sealing plate(s) applying the heat. The higher the temperature, the quicker the interface will be heated. (ii) The time that the heating plate is in contact with the film. Longer times allow more time for heat to be conducted through the film layers to the interface.

[0069] (iii) The pressure of the jaw. Higher pressure means faster heat transfer.

[0070] (iv) The thickness of the film that the heat is being conducted through. The thicker the film, the longer it will take for the interface at the middle to reach a sufficient temperature.

[0071] (v) The thermal conductivity of the layers forming the film. The rate at which heat is transferred across each layer in the film depends on the thermal conductivity of the film. The higher the thermal conductivity, the quicker heat is transferred to the interface.

[0072] As stated above, the time that the heating plate is in contact with the film for, needs to be as short as possible. One way to minimise the time required for the interface temperature to rise sufficiently to cause sealing is to use a high sealing temperature. This is effective but if the temperature is too high (such as > 160 °C), it will thermally damage the layer of the film that is in contact with the sealing plate, leading to visual and other defects around the seal.

[0073] Thus, the thermal stability of the red algae- or brown algae-derived polysaccharide layer and the limited time available for heat sealing is crucial. The onset melting temperature is the temperature at which a composition begins to soften and partially melt. For heat sealing to occur, the materials at the interface must be at or above the onset melting temperature. Controlling the thicknesses of the films allows sufficient heat to be transferred to the interface in the time available whilst giving films of sufficient thickness and robustness to be practical.

[0074] Accordingly, the present invention provides a film comprising: a first layer comprising: at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran; and one or more organic plasticisers; a second layer comprising: at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar; and one or more organic plasticisers; and a third layer, wherein the film contains less than 1 wt% of cations of calcium. The films of the present invention comprise a first layer, a second layer and a third layer. Preferred films of the present invention consist of three layers (i.e. the first layer, the second layer and the third layer). However, the films of the present invention may comprise further layers. As would be understood by a skilled person, adjacent layers in the films of the present invention cannot be compositionally identical (i.e. adjacent layers much have compositions that are distinct enough to allow the two layers to be distinguished from each other by methods known in the art).

[0075] The films of the present invention comprise a first layer comprising at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran. Algae are broadly classified into three categories depending on the pigments in their biomass: as Rhodophyta (red algae), Phaeophyta (brown algae), and Chlorophyta (green algae). The three categories of algae differ in their chemical content and types of carbohydrate, protein and lipids and this results in different biopolymers that can be extracted for industrial applications.

[0076] Macroalgae, otherwise known as seaweed, contain cellulose, as a structural support for cell walls, in different proportions and the voids within this structure are filled with varying levels of polysaccharides. Red seaweed contain significant amounts of agar, carrageenan and furcellaran. Brown seaweed contain significant amounts of alginates.

[0077] In preferred films of the present invention, the red algae- or brown algae- derived polysaccharides are extracted from macroalgae.

[0078] Examples of red macroalgae (or red seaweed) include Eucheuma sp., Furcellaria sp., Gelidiella sp., Gracilaria sp., Gigartina sp., Gelidium sp., Gymnogongrus sp., Hypnea sp., Kappaphycus sp., Lemanea sp., Mastocarpus sp., Palmaria sp., Porphyra sp., Schmitzia sp., Chondrus sp., Mastocarpus sp., Acrochaetium sp., Audouinella sp., Polysiphonia sp., Solieria sp., Vertebrata sp., Pterocladia sp., Acanthopeltis sp., Asparagopsis sp., preferably, Euchema sp., Furcellaria sp., Gelidium sp. or Gracilaria sp., more preferably Euchema cottonii.

[0079] Examples of brown macroalgae (or brown seaweed) include Sargassum sp., Ascophyllum sp., Kelp sp, Saccharina sp., Laminaria sp., Rugelopteryx sp., Ecklonia sp., Durvillea sp., Macrocystis sp. and Lessonia sp..

[0080] In alternative preferred films of the present invention, the red algae- or brown algae-derived polysaccharides are extracted from microalgae. Microalgae are microscopic algae not visible to the naked eye. They are unicellular organisms but can be found in aggregates. The microalgae and macroalgae used to obtain the red algae- or brown algae- derived polysaccharides for the films of the present invention may be obtained from the natural environment (e.g. retrieval when washed up to land by coastal waters), produced through aquaculture in ponds, tanks or tubes or be engineered to produce algae-derived polysaccharides in controlled conditions or industrial-like settings.

[0081] Microalgae and macroalgae are sometimes grown to capture carbon from carbon dioxide or methane for the purpose of reducing greenhouse gases in the atmosphere. The algae is then the source for extraction of algae-derived polysaccharides.

[0082] Alternatively, nature identical polymers can be synthesised chemically outside the algae cells yielding the same materials as would be extracted from naturally grown or cultivated algae.

[0083] Carrageenans, agar and furcellaran are part of a family of polysaccharides typically obtained from the cell walls of red algae. Alginates are part of a family of polysaccharides typically obtained from brown algae. This is in contrast to polysaccharides derived from green algae, such as ulvans.

[0084] Carrageenans, agar and furcellaran are all polysaccharides with a galactose backbone, but differ in the proportion and location of the sulphate ester groups and in the proportion of 3,6-anhydrogalactose.

[0085] Carrageenans are linear anionic sulphated polygalactans formed by disaccharide repeating units and which consists of alternating 3-linked p-d- galactopyranose or 4-linked a-d-galactopyranose or 4-linked 3,6-anhydro-a-d- galactopyranose. There are six different categories based on the degree of free sulphation, but only three are available commercially: iota, kappa and lambda. Carrageenans are used as an additive in the cosmetics, pharmaceutical and food industry mainly for controlling product viscosity and as an emulsifier. Kappa- carrageenan in particular is classified as a food additive as E407. Processed Euchema algae is classified as a food additive number E407a.

[0086] Agar is a linear sulphated polygalactan. It is a heterogeneous polysaccharide comprising agarose (typically 70%) and agaropectin (typically 30%) polymers. It is well known for its gelation properties with most production used in food applications (e.g. it is classified as a food additive as E406) where it can substitute for animal-derived gelatine, as well as in microbiology assays and techniques. Agarose is a linear polysaccharide of repeating units of p-1,3-linked-d-galactose and a-1, 4-linked 3,6- anhydrous-L galactose. Agaropectin has the same backbone as agarose but is slightly branched and contains many anioinic groups such as pyruvate, sulphate, and glycuronate. Furcellaran is an anionic sulphated polysaccharide. It is classified in conjunction with kappa-carrageenan (E407) for use as food additives under European Union legislation. Furcellarans are salts of a linear polymer, composed of [^4)-3,6-anhydro- d-galactopyranose-(1^3)-galactopyranose-4'-sulphate -(1— >] structural units). The weight-average molar mass values reported in the literature vary between values from around 290-500 kDa.

[0087] Alginic acid is a polysaccharide typically obtained from the cell walls of brown algae. Alginic acid is a bio-copolymer of p-D-mannuronic and a-L-guluronic acids which are available in a range of molecular weights and ratios of monomers depending on the source. This results in alginic acid solutions with a range of viscosities. Alginates are widely used in many applications including making films.

[0088] Fucoidans are polysaccharides typically obtained from brown algae that are composed of a backbone of cr(1— >3)-l-fucopyranose residues or of alternating cr(1, 3) and cr(1 ,4)-linked L-fucopyranosyls periodically interrupted by other monosaccharides and sulphate ester groups at two, three and / or four positions of fucopyranose units.

[0089] Laminaran is a storage P-(1 ,3) glucan occasionally containing p-(1 ,6)-linked branches that is also typically obtained from brown algae.

[0090] Fucoidan and laminaran are mostly used for their biological activities rather than gelling or structural properties.

[0091] Thus, in films of the present invention, the at least one red algae- or brown algae-derived polysaccharide in the first layer is selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan (e.g. iota- carrageenan, kappa-carrageenan or lambda-carrageenan) and furcellaran. Preferably, the at least one red algae- or brown algae-derived polysaccharide in the first layer is selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, and carrageenan. More preferably, the at least one red algae- or brown algae- derived polysaccharide in the first layer is a salt of alginic acid wherein the counter ion of the salt is a monovalent ion. Most preferably, the first layer comprises at least one alkali metal salt of alginic acid, preferably lithium alginate, sodium alginate, potassium alginate, or mixtures thereof, more preferably sodium alginate. Alternatively, the first layer comprises ammonium alginate.

[0092] In films of the present invention, the at least one material selected from plant- derived polysaccharides, fungi-derived polysaccharides and agar in the second layer is selected from starch, pullulan and agar.

[0093] Preferred films of the present invention comprise: a first layer comprising based on the total weight of the first layer: at least 20 wt.-% of one or more salts of alginic acid wherein the counter ion of the salt is a monovalent ion, and at least 5 wt.-% of one or more organic plasticisers; a second layer comprising based on the total weight of the second layer: at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar, and at least 5 wt.-% of one or more organic plasticisers; and a third layer, wherein the film contains less than 1 wt% of cations of calcium.

[0094] In preferred films of the present invention, the second layer comprises less than 20 wt.-% of alginic acid salts.

[0095] In preferred films of the present invention, the first layer comprises at least one alkali metal salt of alginic acid, preferably lithium alginate, sodium alginate, potassium alginate, or mixtures thereof, more preferably sodium alginate. Alternatively, the first layer comprises ammonium alginate.

[0096] In preferred films of the present invention, the first layer has a thickness between 3 pm and 115 pm, preferably between 3 pm and 80 pm, preferably between 5 pm and 45 pm, more preferably between 5 pm and 30 pm.

[0097] In preferred films of the present invention, the second layer has a thickness between 1 pm and 80 pm (e.g. between 5 pm and 55 pm), preferably between 1 pm and 15 pm.

[0098] In preferred films of the present invention, the third layer has a thickness between 1 pm and 115 pm, preferably between 1 pm and 80 pm, preferably between 1 pm and 55 pm, more preferably between 1 pm and 45 pm, more preferably between 1 pm and 30 pm, most preferably between 1 pm and 15 pm.

[0099] In preferred films of the present invention, the second layer has an onset melting temperature of less than 100 °C, preferably less than 85 °C, preferably less than 80 °C, determined as described in Example 1 of the specification.

[0100] In preferred films of the present invention, the second layer has an onset melting temperature of at least 55 °C, determined as described in Example 1 of the specification.

[0101] In preferred films of the present invention, the second layer has an onset melting temperature in the range of from 55 °C to 100 °C, preferably from 55 °C to 85 °C, determined as described in Example 1 of the specification.

[0102] In films of the present invention, the second layer comprises a starch and / or pullulan and / or agar. A starch is a carbohydrate polymer that is the main energy store in plants. Starches consist of amylose and / or amylopectin. Amylose is a linear polysaccharide chain that is made up of glucose monomers joined by a o(1,4) glycosidic linkage and it constitutes around 20-30% of starch. Amylopectin is a highly branched polymer made up of glucose subunits. It is made up of linear chains of glucose units that are linked by o(1,4) glycosidic linkages along with a number of side chains that branch the structure by o(1,6) glycosidic linkages and constitutes 70-80% of starch. In the native form, starches are typically in the form of semi-crystalline granules. Sources of starch include but are not limited to fruits, seeds, and rhizomes or tubers of plants.

[0103] Some starches are classified as waxy starches. A waxy starch consists essentially of amylopectin and lacks an appreciable amount of amylose. Typical waxy starches include waxy maize starch, waxy rice starch, waxy potato starch, and waxy wheat starch.

[0104] Alternatively, some starches are classified as high amylose starches.

[0105] Modified starches are prepared by physically, enzymatically, or chemically treating native starch to change its properties. Starches may be modified, for example, by enzymes, by heat treatment, oxidation, or reaction with various chemicals.

[0106] In the films of the present invention, the starch may be a native starch or a modified starch, or a mixture thereof.

[0107] In preferred films of the present invention, the starch is selected from wheat starch, potato starch, pea starch, waxy potato starch, maize starch, waxy maize starch, high amylose maize starch, tapioca starch, cassava starch, rye starch, sorghum starch, chickpea starch, soy starch, or a mixture thereof, preferably potato starch.

[0108] In preferred films of the present invention, the starch is selected from wheat starch, potato starch, pea starch, maize starch, high amylose maize starch, tapioca starch, cassava starch, rye starch, sorghum starch, chickpea starch, soy starch, or a mixture thereof, preferably potato starch.

[0109] In alternative preferred films of the present invention, the starch is a modified starch selected from acid-treated starch, dextrin, alkaline-modified starch, bleached starch, oxidized starch, enzyme-treated starch, maltodextrin, cyclodextrin monostarch phosphate, distarch phosphate, acetylated starch, hydroxypropylated starch, hydroxyethyl starch, starch sodium octenyl succinate, starch aluminium octenyl succinate or cationic starch, or a mixture thereof, preferably acid-treated starch.

[0110] In preferred films of the present invention, the second layer comprises at least one fungi-derived polysaccharide, wherein said fungi-derived polysaccharide is pullulan. Pullulan is a linear polysaccharide composed of 3 maltotriose units linked by an a(1-4) glycosidic bond, where successive maltotriose units are linked to each other by a(1-6) glycosidic linkages. It is produced by the fungus Aureobasidium pullulans by starch fermentation. Pullulan is mainly used by cells to resist desiccation and predation. The presence of this polysaccharide also facilitates diffusion of molecules both into and out of the cell. It is used as a vegetarian substitute for gelatine in pharmaceutical capsules and in other medical applications such as tissue engineering. It is also used as a food additive under E number E1204.

[0111] In preferred films of the present invention, the second layer comprises agar. As described above, agar is a red algae-derived polysaccharide and is a mixture of two components, mainly agarose and agaropectin.

[0112] In films of the present invention, the second layer comprises a starch and / or pullulan and / or agar.

[0113] In preferred films of the present invention, the second layer comprises 40-95 wt% of at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar based upon the total weight of the second layer, preferably 50-80 wt%, more preferably 55-75 wt%.

[0114] Preferred films of the present invention comprise 1-80 wt% of at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar based upon the total weight of the film, preferably 7-70 wt%, more preferably 15-50 wt%.

[0115] Preferred films of the present invention comprise 3-90 wt% of one or more salts of alginic acid wherein the counter ion of the salt is a monovalent ion based upon the total weight of the film, preferably 15-85 wt%, more preferably 25-80 wt%, most preferably 35-70 wt.-% determined according to the HPLC method in Journal of Chromatographic Science 2013; 51 : 208-214.

[0116] In preferred films of the present invention, the film comprises based upon the total weight of the film 3-90 wt.-%, preferably 15-85 wt.-%, more preferably 25-80 wt.- %, most preferably 35-70 wt.-%, of one or more alginic acid salts determined according to the HPLC method in Journal of Chromatographic Science 2013; 51: 208-214.

[0117] Preferred films of the present invention comprise 10-50 wt% of one or more organic plasticisers based upon the total weight of the film, preferably 15-45 wt%, more preferably 20-40 wt%.

[0118] In preferred films of the present invention, the one or more organic plasticisers in the first layer are independently selected from the group consisting of: a) polyols formed by from 1 to 20 repeating hydroxylated units each unit including from 2 to 6 carbon atoms, provided that when the polyol is formed by only one repeating unit it has at least 4 carbon atoms, with the exclusion of sorbitol, b) ethers, thioethers, organic esters, acetals and amino-derivatives of polyols formed by from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms with the exclusion of acetic esters of glycerine, triethyl citrate and tributyl citrate, c) polyol reaction products having from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms with chain extenders, d) polyol oxidation products having from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms including at least one aldehydic or carboxylic functional group or mixtures thereof.

[0119] More preferably, the organic plasticiser in the first layer is selected from glycerol, diglycerin, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethyl propane, poly ether polyols, 2- methyl-1,3-propanediol, ethanolamines, polyethylene glycol, propylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, oleic acid, monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, and mixtures thereof, preferably a mixture of glycerol, sorbitol and oleic acid.

[0120] In preferred films of the present invention, the one or more organic plasticisers are present in the first layer in an amount of 10-50 wt%, more preferably 20-40 wt% on a dry solids basis.

[0121] In preferred films of the present invention, the weight ratio of total alginic acid salts to organic plasticiser in the first layer is in the range 4:1 to 1:1.

[0122] In preferred films of the present invention, the one or more organic plasticisers in the second layer are independently selected from the group consisting of: a) polyols formed by from 1 to 20 repeating hydroxylated units each unit including from 2 to 6 carbon atoms, provided that when the polyol is formed by only one repeating unit it has at least 4 carbon atoms, with the exclusion of sorbitol, b) ethers, thioethers, organic esters, acetals and amino-derivatives of polyols formed by from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms with the exclusion of acetic esters of glycerine, triethyl citrate and tributyl citrate, c) polyol reaction products having from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms with chain extenders, d) polyol oxidation products having from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms including at least one aldehydic or carboxylic functional group or mixtures thereof. More preferably, the organic plasticiser in the second layer is selected from glycerol, diglycerin, polyethylene glycol, propylene glycol, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethyl propane, poly ether polyols, 2-methyl-1,3-propanediol, ethanolamines, sorbitol, mannitol, xylitol, triethyl citrate, oleic acid, monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, and mixtures thereof, preferably a mixture of glycerol and sorbitol.

[0123] Alternatively, the one or more organic plasticisers in the second layer is preferably a sugar surfactant including at least one sugar moiety. Sugar surfactants are preferably composed of at least one, preferably more than two, monosaccharide units linked glycosidically and may include what are termed ‘sugar’ moieties (two monosaccharide units) or from three monosaccharides. The monosaccharides of the sugar moiety may be of the same type (homopolysaccharide) or different (heterosaccharide). Preferably, the sugar surfactant is ionic, more preferably it is anionic, cationic, or amphoteric. More preferably, the sugar surfactant is anionic. The sugar surfactant is preferably selected from functionalised alkyl polyglycosides, fatty acid glucamides, glycinates, glycolipid biosurfactants, such as rhamno-based surfactants (e.g. rhamnolipids) or sophorolipids, or mixtures thereof.

[0124] In preferred films of the present invention, the one or more organic plasticisers are present in the second layer in an amount of 10-50 wt%, more preferably 20-40 wt% on a dry solids basis.

[0125] In preferred films of the present invention, the one or more organic plasticisers in the first layer and / or the second layer are plant-derived.

[0126] In preferred films of the present invention, the weight ratio of the at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar to the one or more organic plasticisers in the second layer is in the range 4:1 to 1:1.

[0127] As would be understood by a skilled person, the one or more organic plasticisers can either be the same in the first and second layer, or the one or more organic plasticisers in the first and second layer can be different. The plasticiser may be emulsified before incorporation to the mixture with the remaining film materials by use of an emulsifier, preferably a non-ionic emulsifier, such as a polysorbate.

[0128] When the film is intended to package a foodstuff, the plasticisers must be suitable for human consumption. Preferred films of the present invention comprise 7.5-35 wt.%, more preferably 10-30 wt.%, most preferably 15-25 wt.%, water based upon the total weight of the film at 55% relative humidity and 20 °C.

[0129] In preferred films of the present invention the first layer further comprises at least one plant-derived carbohydrate or fungi-derived carbohydrate, more preferably a plant-derived carbohydrate, more preferably a plant-derived polysaccharide, most preferably a starch.

[0130] In preferred films of the present invention, the third layer comprises a third layer material.

[0131] In preferred films of the present invention, the third layer comprises a third layer material which is a heat-sealable compound and / or a dispersibility-enhancing compound.

[0132] In preferred films of the present invention, the third layer is the inner layer. More preferably, when the third layer is the inner layer, the first layer is the outer layer and the second layer is the middle layer.

[0133] In preferred films of the present invention, the first layer comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, preferably sodium alginate.

[0134] In preferred films of the present invention, the second layer comprises starch.

[0135] In preferred films of the present invention, the third layer comprises a third layer material which is a heat-sealable compound. Preferably, the heat-sealable compound is selected from animal-derived proteins such as casein and gelatine, pullulan, polyvinyl alcohol, agar, and mixtures thereof. More preferably, the heat-sealable compound is selected from casein, gelatine, pullulan, polyvinyl alcohol, agar, and mixtures thereof.

[0136] In preferred films of the present invention, the third layer comprises a third layer material which is an animal-derived protein such as casein and gelatine, pullulan, polyvinyl alcohol, agar, or mixtures thereof. Preferably, the third layer comprises a third layer material which is casein, gelatine, pullulan, polyvinyl alcohol, agar, or mixtures thereof.

[0137] In preferred films of the present invention, the third layer comprises a third layer material which is a dispersibility-enhancing compound. Preferably, the dispersibilityenhancing compound is selected from animal-derived proteins such as casein and gelatine, pullulan, polyvinyl alcohol, plant-derived proteins such as alkali-treated plant- derived protein, and mixtures thereof. More preferably, the dispersibility-enhancing compound is selected from casein, gelatine, pullulan, polyvinyl alcohol, alkali-treated plant-derived protein, and mixtures thereof. In preferred films of the present invention, the third layer comprises a third layer material which is an animal-derived protein such as casein and gelatine, pullulan, polyvinyl alcohol, a plant-derived protein, or mixtures thereof. Preferably, the third layer comprises a third layer material which is casein, gelatine, pullulan, polyvinyl alcohol, alkali-treated plant-derived protein, or mixtures thereof.

[0138] In preferred films of the present invention, the third layer comprises a third layer material which is both a dispersibility-enhancing compound and a heat-sealable compound. Preferably, said third layer material which is both a dispersibility-enhancing compound and a heat-sealable compound is selected from animal-derived proteins such as casein and gelatine, pullulan and polyvinyl alcohol. More preferably, said third layer material which is both a dispersibility-enhancing compound and a heat-sealable compound is selected from casein, gelatine, pullulan and polyvinyl alcohol.

[0139] In preferred films of the present invention, the third layer comprises polyvinyl alcohol.

[0140] In a particularly preferred film of the present invention, the third layer is the inner layer and comprises polyvinyl alcohol, the first layer is the outer layer and comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, preferably sodium alginate, and the second layer is the middle layer and comprises starch.

[0141] Polyvinyl alcohol (PVOH), a polymer derived from the hydrolysis of polyvinyl acetate and having the generic formula [CH2CH(OH)]„ is the most commonly used water dispersible synthetic polymer to produce films, particularly for use in making detergent laundry pods. PVOH is available in a number of different grades of different degrees of hydrolysis, molecular weights and purities. The choice of grade influences the physical and chemical properties of PVOH, including its solubility, viscosity, thermal properties, film-forming ability and the properties of the film that can be formed. The degree of hydrolysis (DH) of PVOH refers to the extent to which the acetate groups in the polyvinyl acetate precursor have been replaced by hydroxyl groups through hydrolysis (i.e. it quantifies the percentage of acetate groups that have been converted to alcohol groups). Preferably, the degree of hydrolysis of PVOH is in the range 70- 100%, more preferably 75-95%, more preferably 80-90%, even more preferably 85- 90%.

[0142] The polymer molecular weight is also an important parameter as it influences the physical properties of PVOH, particularly its physical properties such as film strength. Preferably, the average molecular weight (as measured by gel permeation chromatography) of PVOH is 1 ,000 Da to 100,000 Da, more preferably 5,000 Da to 70,000 Da, more preferably 10,000 to 60,000 Da, more preferably 15,000 to 50,000 Da, more preferably 20,000 to 40,000 Da, even more preferably 25,000 to 30,000 Da.

[0143] Alternative dispersibility-enhancing compounds are polyvinyl alcohol copolymers such as butenediol-vinyl alcohol copolymers (BVOH); and polyalkylene oxides, such as polyethylene oxides (with a molecular weight in the range of 50,000 Da to 400,000 Da) or polyethylene glycols (PEG).

[0144] Alternative dispersibility-enhancing compounds are chemically modified naturally derived polymers, such as cellulose derivatives, preferably cellulose ethers, methylcellulose, hydroxyethyl cellulose, carboxymethylcellulose, and hydroxypropyl methylcellulose.

[0145] Any suitable plant-derived proteins may be used in the present invention. Plant- derived proteins are mainly comprised of globular proteins which are storage proteins and can be classified as albumins, globulins, prolamins, and glutelins. Globulins and albumins are typically more water soluble than prolamins and glutelins.

[0146] Albumins and globulins are predominately present in all pulses (at greater than 50%) and some pseudo cereals (such as quinoa and amaranth).

[0147] Globulins represent between about 70 and 78 wt% of the protein found in legume seeds, whereas albumins constitute between about 10 and 20 wt% of the protein. Globulins are the storage proteins of most legume seeds. Globulins have higher molecular weights than albumins. The albumins found in pulse proteins are soluble proteins with a variable molecular mass (-12-28 kDa). In typical commercial protein isolates there are generally only residual amounts of albumins present as they are generally removed during the protein extraction process.

[0148] Globulins are typically obtained from soybean, pea, rice, potato, rapeseed, sunflower, lentil, chickpea, bean, fava bean, mung bean, sunflower seed, pumpkin seed, flax, chia, canola, lupine, alfalfa, moringa, borage, hemp seed, and cotton seed; preferably obtained from pea protein, potato protein, rapeseed protein, and / or sunflower protein.

[0149] Prolamins and glutelins make up 85% of protein in the cereal and pseudo cereal families. Prolamins are typically found in wheat, corn, barley and rye whilst glutelins are typically only found in wheat and rice. Prolamins are high in proline and glutamine amino acid content. They have a relatively high fraction of non-polar functionalities. They are less abundant than globulins and are found across fewer plant species. They include gliadin from wheat, hordein from barley, secalin from rye, zein (alpha, beta, gamma) from corn, kafirin from sorghum, avenin from oats. Prolamins are typically much less water soluble than globulins. In preferred films of the present invention, the plant-derived protein is a globulin or albumin plant-derived protein, more preferably a globulin plant-derived protein.

[0150] Preferably, the plant-derived protein is a strengthening compound. More preferably, the plant-derived protein is selected from the group consisting of soybean protein, pea protein, rice protein, potato protein, rapeseed protein, sunflower protein, lentil protein, chickpea protein, bean protein, fava bean protein, mung bean protein, sunflower seed protein, pumpkin seed protein, flax protein, chia protein, canola protein, lupine protein, alfalfa protein, moringa protein, borage protein, hemp seed protein, cotton seed protein, gliadin, hordein, secalin, zein, kafirin, and avenin, preferably selected from pea protein, potato protein, rapeseed protein, and / or sunflower protein.

[0151] Preferably, the plant-derived protein is a dispersibility-enhancing compound. More preferably, the plant-derived protein is selected from the group consisting of soybean protein, pea protein, rice protein, potato protein, rapeseed protein, sunflower protein, lentil protein, chickpea protein, bean protein, fava bean protein, mung bean protein, sunflower seed protein, pumpkin seed protein, flax protein, chia protein, canola protein, lupine protein, alfalfa protein, moringa protein, borage protein, hemp seed protein and cotton seed protein, preferably selected from pea protein, potato protein, rapeseed protein, and / or sunflower protein.

[0152] In preferred films of the present invention the plant-derived protein is chemically or physically treated to increase its dispersibility in water. This process may include denaturing of the plant-derived protein. In preferred films of the present invention, the plant-derived protein is an al kali-treated globulin or albumin plant-derived protein, more preferably an alkali-treated globulin plant-derived protein.

[0153] In preferred films of the present invention, the plant-derived protein is an alkali- treated plant-derived protein.

[0154] In alternative preferred films of the present invention, the third layer is the middle layer. More preferably, when the third layer is the middle layer, the first layer is the outer layer and the second layer is the inner layer.

[0155] In preferred films of the present invention, the first layer comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion.

[0156] In preferred films of the present invention, the second layer comprises starch.

[0157] In preferred films of the present invention, the third layer comprises a third layer material which is a dispersibility-enhancing compound. Preferably, the dispersibilityenhancing compound is selected from animal-derived proteins such as casein and gelatine, pullulan, polyvinyl alcohol, plant-derived proteins such as alkali-treated plant- derived protein, carrageenan, and mixtures thereof. More preferably, the dispersibility- enhancing compound is selected from casein, gelatine, pullulan, polyvinyl alcohol, alkali-treated plant-derived protein, carrageenan, and mixtures thereof.

[0158] In preferred films of the present invention, the third layer comprises a third layer material which is an animal-derived protein such as casein and gelatine, pullulan, polyvinyl alcohol, alkali-treated plant-derived protein, carrageenan, or mixtures thereof. Preferably, the third layer comprises a third layer material which is casein, gelatine, pullulan, polyvinyl alcohol, alkali-treated plant-derived protein, carrageenan, or mixtures thereof.

[0159] In alternative preferred films of the present invention, the third layer is the outer layer. More preferably, when the third layer is the outer layer, the first layer is the middle layer and the second layer is the inner layer.

[0160] In preferred films of the present invention, the first layer comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion.

[0161] In preferred films of the present invention, the second layer comprises starch.

[0162] In preferred films of the present invention, the third layer comprises a third layer material which is a strengthening compound. Preferably, the strengthening compound is carrageenan or a plant-derived protein such as alkali-treated plant-derived protein.

[0163] In preferred films of the present invention, the third layer comprises a third layer material which is carrageenan or a plant-derived protein such as alkali-treated plant- derived protein.

[0164] In preferred films of the present invention, the third layer comprises a plant- derived protein such as alkali-treated plant-derived protein.

[0165] In particularly preferred films of the present invention, the second layer is the inner layer and comprises starch, the first layer is the middle layer and comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, preferably sodium alginate, and the third layer is the outer layer and comprises a plant-derived protein such as alkali-treated plant-derived protein.

[0166] In preferred films of the present invention, the third layer comprises one or more organic plasticisers. Preferably, the one or more organic plasticisers in the third layer are independently selected from the group consisting of: a) polyols formed by from 1 to 20 repeating hydroxylated units each unit including from 2 to 6 carbon atoms, provided that when the polyol is formed by only one repeating unit it has at least 4 carbon atoms, with the exclusion of sorbitol, b) ethers, thioethers, organic esters, acetals and amino-derivatives of polyols formed by from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms with the exclusion of acetic esters of glycerine, triethyl citrate and tributyl citrate, c) polyol reaction products having from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms with chain extenders, d) polyol oxidation products having from 1 to 20 repeating hydroxylated units each including from 2 to 6 carbon atoms including at least one aldehydic or carboxylic functional group or mixtures thereof.

[0167] More preferably, the organic plasticiser in the third layer is selected from glycerol, diglycerin, polyethylene glycol, propylene glycol, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethyl propane, poly ether polyols, 2-methyl-1,3-propanediol, ethanolamines, sorbitol, mannitol, xylitol, triethyl citrate, oleic acid, monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, and mixtures thereof, most preferably selected from glycerol, sorbitol and polyethylene glycol.

[0168] In preferred films of the present invention, the organic plasticiser in the third layer is plant-derived.

[0169] As would be understood by a skilled person, the organic plasticiser in the third layer can either be the same or different to the organic plasticisers in the first and second layers. The plasticiser may be emulsified before incorporation to the mixture with the remaining film materials by use of an emulsifier, preferably a non-ionic emulsifier, such as a polysorbate.

[0170] When the film is intended to package a foodstuff, the plasticiser must be suitable for human consumption.

[0171] Preferred films of the present invention further comprise one or more additives, such as metals, gums, oils, waxes, fragrances, dyes, pigments, opacifiers, bittering agents, antimicrobial agents such as thymol, anti-blocking agents, or structural enhancers such as cellulose nanofibers, cellulose nanocrystals and cellulose fibres.

[0172] As would be understood by a skilled person, said one or more additives can be present in the first and / or second and / or third layer.

[0173] Particularly preferred films of the present invention further comprise a bittering agent. Bittering agents can impart a safety feature to films of the present invention that are not intended to be edible, i.e. to make them unpalatable in the instance that a child or animal were to try and eat them. Preferably, the bittering agent is selected from: capsicinoids, vanillyl ethyl ether, vanillyl propyl ether, vanillyl butyl ether, vanillin propylene, glycol acetal, ethylvanillin propylene glycol acetal, gingerol, 4-(1- menthoxymethyl)-2-(3'-methoxy-4'-hydroxy-phenyl)-1 ,3-dioxolane, pepper oil, pepperoleoresin, gingeroleoresin, nonylic acid vanillylamide, jamboo oleoresin, Zanthoxylum piperitum peel extract, sanshool, sanshoamide, black pepper extract, chavicine, piperine, spilanthol, allyl isothiocyanate, resinferatoxin and mixtures thereof. Particularly preferred bittering agents include capsaicinoids, which includes capsaicin, dihydrocapsaicin, nordihydrocapsaicin, homodihydrocapsaicin, homocapsaicin, and nonivamide. A particularly preferred bittering agent is capsaicin.

[0174] Bittering agents may also be selected from denatonium salts such as denatonium benzoate, denatonium saccharide, denatonium chloride benzoic benzylamine amide, trichloroanisole, methyl anthranilate and quinine (and salts of quinine). Further examples of bittering agents include flavonoids such as quercefin and naringin, naringin, sucrose octaacetate, quassinoids such as quassin and brucine, and agents derived from plant or vegetable matter, such as chemical compounds derived from chilli pepper plants, those derived from a plant species of the genus cynaro, alkaloids and amino acids. Preferably, the bittering agent is selected from the group consisting of denatonium benzoate (e.g. Bitrex®), denatonium saccharide, quinine or a salt of quinine. The chemical name of denatonium is phenylmethyl-[2-[(2,6- dimethylphenyl)amino]-2-oxoethyl]-diethylammonium.

[0175] The bittering agent may have a bitter value of between 1000 and 10,000,000 as measured using the standardized process that is set forth in the European Pharmacopoeia (5th Edition, Stuttgart 2005, Volume 1, General Monograph 15 Groups, 2.8.15 Bitterness Value, p. 278).

[0176] In preferred films of the present invention, the bittering agent is present in the film in a range of 100 to 5000 ppm, preferably 200 to 3000 ppm, more preferably 500 to 2000 ppm, based on the total weight of the bittering agent and film.

[0177] As would be understood by a skilled person, said bittering agent can be present in the first and / or second and / or third layer.

[0178] Additionally or alternatively, the bittering agent may be provided as a powdered bittering agent in a powder coating applied to the outer surface of the film.

[0179] Preferred films of the present invention further comprise a phyllosilicate. Preferably, said phyllosilicate is a serpentine mineral, a clay mineral, a chlorite mineral or a mica mineral, or mixtures thereof, preferably a clay mineral, preferably a clay mineral selected from bentonite, kaolinite, pyrophyllite, vermiculite and a smectite (e.g. montmorillonite, cloisite, laponite, hectorite etc.), or mixtures thereof.

[0180] As would be understood by a skilled person, said phyllosilicate can be present in the first and / or second and / or third layer.

[0181] In preferred films of the present invention, the film includes a powder coating on an outer surface, and the powder coating includes a powdered lubricating agent. As would be understood by a skilled person, a powder coating does not equate to the first layer, second layer or third layer of the films of the present invention. Rather, a powder coating is applied to the final film and is typically a discontinuous covering of discreet individual particles over the surface of the film. The powder coating may be applied to least 50%, preferably at least 60%, at least 70%, even more preferably at least 80%, most preferably at least 90% percent by area of the outer surface of the film. The powder coating can be applied by any known technique such as spray-coating or passing the film through a falling curtain of powder coating composition. The powder coating may be applied to the outer surface of the film at a rate of 0.5 to 10mg per 100cm2, preferably not more than 5mg per 100cm2, and further preferably in the range of 1.25 to 2.5mg per 100cm2. The powder coating may be applied to or is present on the outer surface of the film in an amount of 100 ppm or more, preferably 200 ppm or more, more preferably 300 ppm or more, based on the total weight of the powder coating and the film. Particularly preferably, the powder coating is applied to or is present on the outer surface of the film in a range of 100 to 5000 ppm, preferably 200 to 3000 ppm, more preferably 300 to 2000 ppm.

[0182] Preferred films of the present invention are made exclusively from food-grade materials.

[0183] In preferred films of the present invention, the film is more than 75%, preferably more than 80%, more preferably more than 85%, even more preferably more than 90%, most preferably more than 95% biodegradable, in fresh water according to ISO 14851 after 28 days testing.

[0184] In preferred films of the present invention, the film is more than 75 %, preferably more than 80 %, more preferably more than 85 %, even more preferably more than 90 %, most preferably more than 95 % biodegradable, in marine water according to ASTM D6691 after 28 days testing.

[0185] In preferred films of the present invention, the film has a thickness of between 20 pm and 120 pm.

[0186] In preferred films of the present invention, the film has a heat sealing strength of at least 30 N / m, preferably at least 50 N / m, more preferably at least 100 N / m, as measured by ASTM F88 / F88M-15 at 55% relative humidity and 20 °C after the film has been conditioned at 55 % relative humidity and at 20 °C for at least one hour and then sealed as either a fin seal or a lap seal at a temperature of 140 °C and a pressure of between 1 and 3 bar applied for a time of 1 second.

[0187] In preferred films of the present invention, the tensile strength of the film is at least 1 MPa as measured according to ASTM D882.

[0188] In the films of the present invention, the film is substantially free of cations of calcium. Preferably, the film does not contain any cations of calcium. The absence of cations of calcium in the films of the present invention aids their water dispersibility and biodegradability.

[0189] The present invention also provides a process for preparing a film as hereinbefore described, comprising the steps of:

[0190] (i) providing a first layer comprising at least one red algae- or brown algae- derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran, and one or more organic plasticisers;

[0191] (ii) providing a second layer comprising at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar, and one or more organic plasticisers;

[0192] (iii) providing a third layer; and

[0193] (iv) forming said first layer, said second layer and said third layer into said film, wherein the film contains less than 1 wt% of cations of calcium.

[0194] As would be understood by a skilled person, steps (i), (ii) and (iii) can be performed in any order. Accordingly, in step (iv) the first layer, second layer and third layer can be formed into the film in any order.

[0195] In preferred processes of the present invention, step (iv) involves depositing onto and adhering one surface of a layer to one surface of another layer. As would be understood by a skilled person, depositing onto and adhering one surface of a layer to one surface of another layer does not require there to be a full contact at all points along the interface. Rather, discontinuous contact is envisaged whereby voids, pockets or compartments can be created. Alternatively, continuous contact is also envisaged such that depositing onto and adhering one surface of a layer to one surface of another layer does require there to be a full contact at all points along the interface. As would be understood by a skilled person, continuous contact or discontinuous contact can also be achieved when sealing films of the present invention together.

[0196] In preferred processes of the present invention, step (i) involves use of a preformed first layer.

[0197] In preferred processes of the present invention, step (ii) involves use of a preformed second layer.

[0198] In preferred processes of the present invention, step (iii) involves use of a preformed third layer. In preferred processes of the present invention, step (i) involves forming said first layer. Preferably, said first layer is formed by a casting method, a lamination method or an extrusion method.

[0199] In preferred processes of the present invention, step (ii) involves forming said second layer. Preferably, said second layer is formed by a casting method, a lamination method or an extrusion method.

[0200] In preferred processes of the present invention, step (iii) involves forming said third layer. Preferably, said third layer is formed by a casting method, a lamination method or an extrusion method.

[0201] A preferred process of the present invention comprises the steps of:

[0202] (a) mixing the at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran and the at least one organic plasticiser in water to form a mixture (a);

[0203] (b) forming the mixture (a) into said first layer on a surface;

[0204] (c) mixing the at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar and the at least one organic plasticiser in water to form a mixture (b);

[0205] (d) forming the mixture (b) into said second layer on said first layer; and

[0206] (e) providing a third layer on said second layer.

[0207] Preferably, step (a) involves additionally mixing at least one plant-derived carbohydrate or fungi-derived carbohydrate to form said mixture (a).

[0208] Preferably, in step (b) mixture (a) is at a temperature in the range 40 to 85 °C, more preferably 50 to 60 °C.

[0209] Alternatively, in step (b) mixture (a) is preferably at ambient temperature.

[0210] Preferably, step (c) is conducted at a temperature in the range 10 to 90 °C.

[0211] Preferably, in step (d) mixture (b) is at a temperature in the range 40 to 85 °C, more preferably 50 to 60 °C.

[0212] Preferably, in step (d) mixture (b) is at ambient temperature.

[0213] Preferably, prior to step (d) mixture (b) is degassed.

[0214] Preferably, step (e) comprises the steps of:

[0215] (i) mixing a third layer material, and optionally at least one organic plasticiser, in water to form a mixture (c);

[0216] (b) forming the mixture (c) into said third layer on said second layer.

[0217] An alternative preferred process of the present invention comprises the steps of: (a) providing a third layer on a surface;

[0218] (b) mixing the at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran and the at least one organic plasticiser in water to form a mixture (d);

[0219] (c) forming the mixture (d) into said first layer on said third layer;

[0220] (d) mixing the at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar and the at least one organic plasticiser in water to form a mixture (e); and

[0221] (e) forming the mixture (e) into said second layer on said first layer.

[0222] Preferably, step (a) comprises the steps of:

[0223] (i) mixing a third layer material, and optionally at least one organic plasticiser, in water to form a mixture (f);

[0224] (b) forming the mixture (f) into said third layer on a surface.

[0225] Preferably, step (b) involves additionally mixing at least one plant-derived carbohydrate or fungi-derived carbohydrate to form said mixture (d).

[0226] Preferably, in step (c) mixture (d) is at a temperature in the range 40 to 85 °C, more preferably 50 to 60 °C.

[0227] Preferably, in step (c) mixture (d) is at ambient temperature.

[0228] Preferably, step (d) is conducted at a temperature in the range 10 to 90 °C.

[0229] Preferably, in step (e) mixture (e) is at a temperature in the range 40 to 85 °C, more preferably 50 to 60 °C.

[0230] Preferably, in step (e) mixture (e) is at ambient temperature.

[0231] Preferably, prior to step (e) mixture (e) is degassed.

[0232] An alternative preferred process of the present invention comprises the steps of:

[0233] (a) mixing the at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran and the at least one organic plasticiser in water to form a mixture (g);

[0234] (b) forming the mixture (g) into said first layer on a surface;

[0235] (c) providing a third layer on said first layer;

[0236] (d) mixing the at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar and the at least one organic plasticiser in water to form a mixture (h); and (e) forming the mixture (h) into said second layer on said third layer.

[0237] Preferably, step (a) involves additionally mixing at least one plant-derived carbohydrate or fungi-derived carbohydrate to form said mixture (g).

[0238] Preferably, in step (b) mixture (g) is at a temperature in the range 40 to 85 °C, more preferably 50 to 60 °C.

[0239] Preferably, in step (b) mixture (g) is at ambient temperature.

[0240] Preferably, step (c) comprises the steps of:

[0241] (i) mixing a third layer material, and optionally at least one organic plasticiser, in water to form a mixture (i);

[0242] (b) forming the mixture (i) into said third layer on said first layer.

[0243] Preferably, step (d) is conducted at a temperature in the range 10 to 90 °C.

[0244] Preferably, in step (e) mixture (h) is at a temperature in the range 40 to 85 °C, more preferably 50 to 60 °C.

[0245] Preferably, in step (e) mixture (h) is at ambient temperature.

[0246] Preferably, prior to step (e) mixture (h) is degassed.

[0247] In preferred processes of the present invention, the one or more layers are independently made by casting or blown film extrusion, preferably by casting, more preferably solvent casting.

[0248] Solvent casting can be a two-step process where a first layer of material is cast onto a substrate such as Mylar®, or corona treated Mylar® or a metal belt. The mixture cast can be at room temperature or heated. Immediately after coating the material is dried in an oven and the film is reeled onto a core. The roll of first layer (which may still be on the Mylar®) is unpeeled from the roll and reeled through the line again so a second layer can be cast on top of the first layer and again dried in the oven. Again the mixture cast can be at room temperature or heated. This process can be described as a “wet-on-dry process”. To control the casting thickness, the casting line is equipped with a system of metallic rollers where the gap between rollers controls the wet thickness of the coating. The line speed and oven temperature are adjusted to obtain the desired dry film thickness and final moisture content. The final dry film is peeled from the backing substrate and is then rolled onto a core and stored until required for wrapping or enclosing a product and optionally sealing the film to form a sachet.

[0249] Solvent casting can also be a one-step continuous process where a first layer of material is cast onto a substrate such as Mylar®, corona treated Mylar® or a metal belt. The mixture cast can be at room temperature or heated. After coating and drying, or partially drying, in an oven, the second layer can be cast on top of the first layer and finally dried in a second oven. Again the mixture cast can be at room temperature or heated. This process can be described as a “wet-on-wet process” or “wet-on-semi-dry process”. To control the casting thickness, the line is equipped with a system of metallic rollers where the gap between rollers controls the wet thickness of the coatings. The line speed and oven temperatures are adjusted to obtain the desired final dry film thickness and final moisture content. The final dry film is peeled from the backing substrate and is then rolled onto a core and stored until required for wrapping or enclosing a product and optionally sealing the film to form a sachet.

[0250] In both solvent casting processes, it is important to that the final roll of film can be unwound easily and without damaging the film. This is necessary either in the intermediate part of the wet-on-dry process or when using the final film in a product packing line.

[0251] Preferred processes of the present invention further comprise a step of microperforating the film. Such as step can be advantageous when the product to be enclosed by the film is, for example, a powdered product as the microperforation can help with release of the powder during use.

[0252] The present invention also provides a film obtained by or obtainable by a process as hereinbefore described.

[0253] The present invention also provides a product enclosed by a film as hereinbefore described.

[0254] In a preferred product of the present invention, the film is made exclusively from food-grade materials.

[0255] In an alternative preferred product of the present invention, the film is more than 75 %, more preferably more than 80 %, even more preferably more than 85 %, even more preferably more than 90 %, most preferred more than 95 % biodegradable, in fresh water according to ISO 14851 (2019) after 28 days testing.

[0256] In an alternative preferred product of the present invention, the film is more than 75 %, more preferably more than 80 %, even more preferably more than 85 %, even more preferably more than 90 %, most preferably more than 95 % biodegradable in marine water, according to ASTM D6691 after 28 days testing.

[0257] A preferred product of the present invention is a foodstuff, a pharmaceutical product, a cleaning product, an agricultural product (e.g. an animal feed or medication), a chemical product or a cosmetic product.

[0258] A preferred product of the present invention is a solid or powdered product having a water activity of less than 0.65. Preferably, the product is a solid or powdered product having a water activity in the range 0.25 to 0.65, more preferably in the range 0.35 to 0.55 (e.g. 0.45).

[0259] A preferred product of the present invention is a solid product selected from a soup or flavouring preparation (e.g. a stock cube), a personal cleanser (e.g. a soap bar, body scrub or solid shampoo), a laundry detergent tablet or bar or a dishwasher detergent tablet, preferably a stock cube, a laundry detergent tablet or a dishwasher detergent tablet.

[0260] An alternative preferred product of the present invention is a powdered product selected from a powdered food, a powdered drink, powdered milk, powdered soup, powdered hot chocolate, powdered coffee, powdered tea, tea leaves, soap flakes, powdered laundry detergent, and powdered shampoo, preferably, a powdered drink.

[0261] A preferred product of the present invention is an aqueous liquid product, preferably selected from a homecare or cleaning product or a hair care or body care product, having a water activity of less than 0.65. Preferably, the product is an aqueous liquid product having a water activity in the range 0.25 to 0.65, more preferably in the range 0.35 to 0.55 (e.g. 0.45).

[0262] A preferred product of the present invention comprises a total water content of less than about 25 wt% with respect to the total weight of the product when measured at 55% relative humidity (RH) and 20 °C.

[0263] An alternative preferred product of the present invention is an oil or water-less liquid, preferably a body care oil or an anhydrous liquid detergent.

[0264] The present invention also provides a method of enclosing a product, comprising the steps of:

[0265] (i) wrapping the product in a film as hereinbefore described; and

[0266] (ii) heat sealing the film around the product to form a sachet.

[0267] Preferred products are as described above.

[0268] In preferred methods of the present invention, step (ii) involves the formation of a fin seal or a lap seal, preferably a fin seal.

[0269] In preferred methods of the present invention, the duration of step (ii) is less than 2 seconds, more preferably less than 1 second, more preferably less than 0.5 seconds.

[0270] In preferred methods of the present invention, step (ii) is conducted at a temperature of less than 160 °C, preferably less than 140 °C, more preferably less than 120 °C.

[0271] The present invention also provides a sachet prepared by a method as hereinbefore described.

[0272] Preferably, the sachet of the present invention is water dispersible.

[0273] The films of the present invention have a high dispersibility in water. This means that they can be used as a packaging material for a product that creates zero waste during end use of the product. For example, the films of the present invention could be used to package a detergent such that during the washing process the film will disperse in water to release the detergent. Alternatively, the films of the present invention could be used to package a foodstuff such that during the cooking process the film will disperse in water to release the foodstuff.

[0274] The present invention also provides the use of a film as hereinbefore described to enclose a product and / or to prepare a sachet.

[0275] Preferred products are as described above.

[0276] The present invention also provides a method of releasing a product enclosed in a film as hereinbefore described, comprising the steps of:

[0277] (i) placing the enclosed product in water; and

[0278] (ii) allowing the film to disperse, thereby releasing the product.

[0279] Preferred products are as described above.

[0280] In a preferred method of the present invention, the product is released in step (ii) during a cooking process.

[0281] In a preferred method of the present invention, the product is released in step (ii) during a washing process.

[0282] BRIEF DESCRIPTION OF THE FIGURES

[0283] Figure 1a is a schematic of a film of the present invention prepared by casting the first layer on a substrate, followed by the second layer on top of the first layer and finally the third layer on top of the second layer. The preparation of such a film is described in Examples 7 and 11.

[0284] Figure 1b is a schematic of a film of the present invention prepared by casting the first layer on a substrate, followed by the third layer on top of the first layer and finally the second layer on top of the third layer. The preparation of such a film is described in Example 9.

[0285] Figure 1c is a schematic of a film of the present invention prepared by casting the third layer on a substrate, followed by the first layer on top of the third layer and finally the second layer on top of the first layer. The preparation of such a film is described in Examples 8 and 10.

[0286] EXAMPLES

[0287] Materials

[0288] Alginic acid sodium salt was purchased from Thermo Fisher Scientific. The viscosity of a 1 % solution of alginic acid sodium salt at 20 °C was between 350 and 550 mPas.

[0289] Kappa-carrageenan was purchased from Tokyo Chemical Industries (TCI), Japan. Tapioca starch (Alpha Instant), potato starch (pre-gelled), maize starch and rice starch were purchased from BakeRite.

[0290] Food-grade glycerol (APC Pure), propylene glycol and potato starch (hot soluble) were purchased from APC.

[0291] Antifoam agent (aqueous-silicone emulsion), Polysorbate 80, polyvinyl alcohol (PVOH) and maize amylopectin (starch from corn) were purchased from Sigma-Aldrich Co.

[0292] Pullulan was purchased from Rongsheng Biotechnology Co. Ltd.

[0293] Maltodextrin and sodium hydroxide was purchased from Sigma-Aldrich Co.

[0294] Pea protein Isolate (80% protein, 4 wt% carbohydrate - ProEarth P16109) was purchased from Cambridge Commodities.

[0295] Oleic acid and sorbitol were purchased from Thermo Fisher Scientific.

[0296] Example 1 - onset melting temperature and sealing strength for polysaccharide monolayers

[0297] (i) Preparation of polysaccharide monolayers

[0298] 10.0g of carbohydrate was dispersed in 100 ml of deionised water at ambient temperature, in a 250 ml flask by overhead stirring. 4.29g of glycerol was then added and the suspension stirred. The suspension was then sonicated using a Bandelin sonicator for 10 minutes at an amplitude of 95%, with a cycle of 1 second on, 0.2 seconds off. The solution was then placed in a sonicator bath for 1 min at 80 °C to remove any bubbles.

[0299] 20 ml of the solution was poured into a 50 ml Falcon tube. The solution was then further degassed by removing large bubbles with a pipette, before being allowed to cool to 55 °C and poured onto a flat glass plate having a Mylar® surface. The liquid was spread out uniformly using a doctor blade to give a wet film of approximately 400 microns thickness. The plate was then put in the oven for 50 minutes at 80 °C to dry the layer of film.

[0300] (ii) Measurement of onset melting temperature by Differential Scanning Calorimetry (DSC)

[0301] The films produced in step (i) were conditioned overnight at 55% relative humidity and 20°C. The onset melting temperature is a function of the whole film composition including moisture level. A small test sample (10-20mg) was cut from each film and accurately weighed. Each sample was placed in 40 pL aluminium pans (#51119870, purchased from Mettler Toledo), and heated from 25°C to 160°C at a heating rate of 10°C / min in a nitrogen atmosphere using a DSC822e from Mettler Toledo. The pan lid was pierced using a 50pm diameter needle prior to the sealing. An empty pan was used as a reference. The normalised heat flow was recorded and plotted as a function of temperature.

[0302] The onset melting temperature of a sample is defined as the first inflection point in the DSC curve showing a rate increase in the heat flow to the sample with increasing temperature. As the sample starts to melt, the heat flow to the sample increases, thus creating a change of gradient and an inflection point in the graph.

[0303] Normalised heat flow plots can be visually assessed by an operator to determine the inflection point in the graph. However, this analysis is now typically done using software analysis tools. Such analysis tools are typically included as part of the equipment operating system. Suitable software includes the STARe evaluation software supplied by Mettler-Toledo.

[0304] Data from the normalised DSC plots obtained above was analysed using the STARe evaluation software version 16.30 to determine onset melting temperatures. Results are shown in Table 1 below. The thermal properties of a starch mixture are a complex combination of the relative ratio of amylose to amylopectin in the starch, prior thermal treatments and the level and nature of other ingredients.

[0305] Table 1 All of the tested materials were found to have a sufficiently low onset melting temperature to render them effective sealing surfaces in a heat sealing process.

[0306] (iii) Determination of sealing strength

[0307] Test samples of some of the layers produced in step (i) were prepared and subjected to a seal strength measurement. Test samples of width 25 mm were cut to the dimensions given in ASTM F88 / F88M-15 and conditioned overnight at 55% relative humidity (RH) and 20°C. Test strip samples were then sealed using an RDM heat sealer to give a fin seal. Sealed test specimens were tested using technique A (unsupported) in a Tinnius Olsen tensile tester. A sealing temperature of 100 °C and a dwell time of 1 second were employed. The results are shown in Table 2 below.

[0308] Table 2

[0309] As demonstrated above, the onset melting temperature of a material relates inversely to its ability to form a strong seal. For example, the STT-based layer has a lower onset melting temperature and forms a strong seal. The BPS-based layer has a higher onset melting temperature and forms a good seal, but this is not as strong as the STT-based seal.

[0310] A lower onset melting temperature for the carbohyd rate-containing layer of the multilayer films of the present invention is advantageous for multiple reasons. Not only has it been demonstrated that a stronger seal strength can be achieved, but a lower onset melting temperature means that a lower temperature need be applied to the outer layer of the multilayer films of the present invention in order to result in effective sealing of the inner layer. This means that the film degradation (e.g. as a result of burning) is avoided, and also that shorter dwell times are required to form the seal, making the sealing process more industrially viable.

[0311] Example 2 (comparative): Preparation of alginate - starch bilayer film

[0312] (i) Preparation of alginate mixture 400ml of water was mixed with 14g of alginic acid in a 600 ml beaker at ambient temperature using an overhead stirrer to form a homogenous solution. 6g of glycerol was then added with stirring and 4 drops of antifoam agent. The mix was stirred for 45 minutes. The mix was then further degassed under vacuum using a Hauschild Speedmixer.

[0313] (ii) Film formation - alginate layer

[0314] 25 ml of the mix produced in step (i) was poured into a 50 ml Falcon tube. The mix was removed and poured onto a flat glass plate having a Mylar® surface. The liquid was spread out uniformly over the plate using a doctor blade to give a wet film of the alginate mix of 1100 microns. The glass plate was then dried overnight at ambient temperature to form the dried film layer.

[0315] (iii) Preparation of starch mixture

[0316] 40.0g of tapioca starch (STT) was dispersed in 400ml of deionised water at ambient temperature in a 600 ml flask by overhead stirring. 17.14g of glycerol was then added and the suspension stirred. The suspension was then sonicated using a Bandelin sonicator Sonopuls probe TS113 for 40 minutes at an amplitude of 95%, with a cycle of 1 second on, 0.2 seconds off. The solution was then placed in a sonicator bath for 1 minute at 80 °C to remove any bubbles.

[0317] (iv) Film formation - starch layer

[0318] 7 ml of the mix produced in step (iii) was poured into a 50 ml Falcon tube. The mix was then further degassed by removing large bubbles with a pipette, before being allowed to cool to 55 °C and then spread over the exposed surface (i.e. the surface not in contact with the glass plate) of the dried film prepared in step (ii) using a doctor blade to give a wet film of the starch mix of approximately 250 microns thickness. The plate was then put in the oven for 30 minutes at 80 °C to form the dry film.

[0319] The bilayer film was obtained by peeling the dry film from the substrate. The bilayer film had a thickness of 58 microns.

[0320] Example 3 - Properties of the film of Example 2 Measurement of film tensile strength and elongation

[0321] Measurement of film tensile strength and elongation was tested according to ASTM D882. Rectangular test samples of length 80mm and width 10 mm were cut (which falls within the described specifications in ASTM D882) and conditioned overnight at 55% relative humidity (RH) and 20°C. The test samples were tested using a Tinius Olsen 5ST tensile tester with flat grip inserts, an initial grip separation of 50mm and a testing speed of 50mm / min (strain rate of 1mm / mm*min).

[0322] Utmost care was exercised in cutting specimens to prevent nicks and tears that cause premature failures and ensure repetitive sample guality.

[0323] The film of Example 2 was found to demonstrate acceptable tensile strength and elongation: the tensile strength of the film was 23.9 MPa and the elongation at break was 36.7%.

[0324] Measurement of seal strength

[0325] Test samples of width 25 mm were cut to the dimensions given in ASTM F88 / F88M-15 and conditioned overnight at 55% relative humidity and 20°C. Test strip samples were then sealed using an RDM heat sealer to give a fin seal. Sealed test specimens were tested using technigue A (unsupported) in a Tinius Olsen 5ST tensile tester. A sealing temperature of 140 °C and a dwell time of 1 second and pressure of 3 bar were employed. The maximum force encountered as the film of Example 2 was stressed to failure was found to be high at 746 Newtons / meter (N / m).

[0326] The film of Example 2 was taken on for further seal strength testing, at different seal temperatures and dwell times with a pressure of 3 bar. The results are shown in Table 3 below. Table 3

[0327] The results show that the longer the dwell time, the lower the temperature required to achieve an effective seal strength.

[0328] • Water dispersibility

[0329] The water dispersibility of the film of Example 2 was assessed using 0.75g samples conditioned at 55% relative humidity (RH) and a temperature of 20°C. Samples were mixed at room temperature using an overhead stirrer at 300 rpm in 300 ml of both reverse osmosis water at 20°C and freshly boiled reverse osmosis water (i.e. having a temperature range 75°C to 90°C) in a 600 ml beaker for 3 minutes. The end mix was visually inspected for any remaining particles, and their size used to judge water dispersibility on the following scale: Very low - majority of particles >30mm; Low - majority of particles ~20-30mm; Average - majority of particles ~10-20mm; High - majority of particles ~1-10mm; Very high - majority of particles <1mm; Maximum - no visible particles. Dispersibility can be reported as individual values or as an average of the two different temperature observations, wherein each observation can be assigned an integer value for these purposes.

[0330] The water dispersibility of the film of Example 2 was found to be “high” as an average of the two different temperature observations.

[0331] Example 4 (comparative): Preparation of carrageenan - starch bilayer film

[0332] (i) Preparation of carrageenan mixture

[0333] 1. Preparation of an oil-in-water emulsion: Weighed 3.25 g of oleic acid and 1.60g of Polysorbate 80 and mixed them with 20mL of water in a 50mL falcon tube. Sonicated them for 5 min at 50% amplitude, 1 sec on and 0.2 sec off intervals using a Bandelin Sonoplus sonicator (TS113 probe).

[0334] 2. While cooling down the emulsion, weighed 996.2g reverse osmosis (RO) water, 6.67g glycerol and 6.67g sorbitol in a 2L plastic beaker. Mixed well with a spatula.

[0335] 3. 4.73g cooled down emulsion was added to the plasticiser-water mix.

[0336] 4. Transfered the mixture to a Karlestein GrandPrix food processor, and added 20g of kappa-carrageenan

[0337] 5. Mixed at speed 7 at 30 °C for 30 minutes. (ii) Film formation - carrageenan layer

[0338] 6. Moved the mixed formulation to the Hauschild speed mixer container and degassed it for 5 min at 1950rpm at 3 mbar.

[0339] 7. Immediately cast the solution after speed mixing to a wet thickness of 1700 pm, using a RK Print K303S multi coater at speed 2 using a doctor blade.

[0340] 8. The film was then dried in the oven at 80 °C for 3 hours.

[0341] (iii) Preparation of starch mixture

[0342] 1. Weighed 500g of RO water, 10.7g of glycerol, 10.7 g of sorbitol in a 1L plastic beaker. Mixed well using a spatula.

[0343] 2. Transfered the solution to a Karlstein GrandPrix food processor, and added 50g of tapioca starch.

[0344] 3. Mixed at speed 4, 85 °C for 45 minutes.

[0345] (iv) Film formation - starch layer

[0346] 4. Transfered the mixture to the Hauschild Speedmixer container and degassed it for 5 min at 1950 rpm at 3 mbar.

[0347] 5. Cast the solution onto the kappa-carrageenan layer while it was warm to a 300 pm wet thickness using a doctor blade, speed 3.

[0348] 6. The film was then dried at 80 °C for 30 minutes in an oven.

[0349] The bilayer film was obtained by peeling the dry film from the substrate. The bilayer film had a thickness of 69 microns.

[0350] Example 5: Properties of the film of Example 4

[0351] • Measurement of film tensile strength and elongation

[0352] Measurement of film tensile strength and elongation was tested according to ASTM D882. Rectangular test samples of length 80mm and width 10 mm were cut (which falls within the described specifications in ASTM D882) and conditioned overnight at 55% RH and 20°C. The test samples were tested using a Tinius Olsen 5ST tensile tester with flat grip inserts, an initial grip separation of 50mm and a testing speed of 50mm / min (strain rate of 1mm / mm*min). Utmost care was exercised in cutting specimens to prevent nicks and tears that cause premature failures and ensure repetitive sample quality.

[0353] The film of Example 4 was found to demonstrate acceptable tensile strength and elongation: the tensile strength of the film was 23.1 MPa and the elongation at break was 28.7%.

[0354] • Measurement of seal strength

[0355] Measurements were completed according to the method described in Example 3, except that both a fin seal and a lap seal was tested. The maximum force encountered as the sample of Example 4 was stressed to failure was high: 376.4 Newtons / meter (N / m) for a fin seal and 183.6 n / m for a lap seal.

[0356] The film of Example 4 was taken on for further seal strength testing, at different seal temperatures and dwell times with a pressure of 3 bar. The results are shown in Table 4 below.

[0357] Table 4

[0358] The results show that for a comparative bilayer film, there is an ideal temperature range to obtain an effective seal strength. At low temperatures the seal strength is too low and at very high temperatures seal strength starts to drop.

[0359] • Water dispersibility

[0360] The water dispersibility was measured according to the method described in Example 3. The water dispersibility of the film of Example 4 was found to be “not dispersible” at room temperature and “high” in freshly boiled water.

[0361] Example 6: Moisture content of films

[0362] The moisture content of various films prepared in the above examples was measured using an Ohaus MB23 moisture analyser, wherein the film samples had first been conditioned at 55% relative humidity (RH) and a temperature of 20°C. The results are shown in Table 5 below.

[0363] Table 5

[0364] Example 7 - Preparation of a polyvinyl alcohol - starch - alginate film

[0365] A triple layer film comprising a first layer of alginate, and second layer of starch and a third layer of polyvinyl alcohol (PVOH) is prepared. The first layer is formed first on a Mylar® substrate, followed by the second layer on top of the first layer and finally the third layer on top of the second layer as shown in Figure 1a.

[0366] (i) Preparation of alginate mixture

[0367] 400ml of water is mixed with 14g of alginic acid in a 600 ml beaker at ambient temperature using an overhead stirrer to form a homogenous solution. 6g of glycerol is then added with stirring and 4 drops of antifoam agent. The mix is stirred for 45 minutes. The mix is then further degassed under vacuum using a Hauschild Speedmixer.

[0368] (ii) Film formation - alginate layer

[0369] 25 ml of the mix produced in step (i) is poured into a 50 ml Falcon tube. The mix is removed and poured onto a flat glass plate having a Mylar® surface. The liquid is spread out uniformly over the plate using a doctor blade to give a wet film of the alginate mix. The glass plate is then dried overnight at ambient temperature to form the dried film layer.

[0370] (iii) Preparation of starch mixture

[0371] 40.0g of tapioca starch (STT) is dispersed in 400ml of deionised water at ambient temperature in a 600 ml flask by overhead stirring. 17.14g of glycerol is then added and the suspension stirred. The suspension is then sonicated using a Bandelin Sonopuls sonicator (Probe TS113) for 40 minutes at an amplitude of 95%, with a cycle of 1 second on, 0.2 seconds off. The solution is then placed in an ultrasonic bath for 1 minute at 80 °C to remove any bubbles.

[0372] (iv) Film formation - starch layer

[0373] 7 ml of the mix produced in step (iii) is poured into a 50 ml Falcon tube. The mix is then further degassed by removing large bubbles with a pipette, before being allowed to cool to 55 °C and then spread over the exposed surface (i.e. the surface not in contact with the glass plate) of the dried film prepared in step (ii) using a doctor blade to give a wet film. The plate is then put in the oven for 30 minutes at 80 °C to form the multilayer film.

[0374] (v) Preparation of PVOH mixture

[0375] In a Klarstein Grand Prix food processor (500W power, 2.5 litre capacity) fitted with 4 standard stainless steel blades, while mixing at Speed 4, the following room temperature materials are added: reverse osmosis water, one or more plasticisers selected from glycerol, sorbitol or polyethylene glycol, and PVOH in the quantities and ratios understood by a skilled person. The food processor is set at a temperature of 85°C and left to mix for 60 minutes, whilst every 10 minutes scooping the material that accumulates on the walls back into the mixture. The mixture is then transferred to a Hauschild Speedmixer for 3 minutes at 50mBars and 1500 rpm and then left to cool to room temperature.

[0376] (vi) Film formation - PVOH layer

[0377] A suitable quantity of the mixture is poured, at room temperature and then spread over the exposed surface (i.e. the surface not in contact with the glass plate) of the dried film prepared in step (iv) using a RK Print K303S multi coater with a Doctor Blade. Blade settings are carefully chosen by the skilled person, in order to give upon drying the desired dried-film thickness, which are reflected by the above-mentioned suitable quantity of the mixture as well as its wet thickness. The glass plate is then dried in the oven at 50°C to form a dried film.

[0378] The triple layer film is obtained by the peeling the dried film from the substrate.

[0379] Example 8 - Preparation of a starch - alginate - carrageenan film

[0380] A triple layer film comprising a first layer of alginate, and second layer of starch and a third layer of carrageenan is prepared. The third layer is formed first on a Mylar® substrate, followed by the first layer on top of the third layer and finally the second layer on top of the first layer as shown in Figure 1c.

[0381] (i) Preparation of kappa-carrageenan mixture

[0382] 3.25g of oleic acid and 1 ,60g of polysorbate 80 are mixed with 20m L of reverse osmosis (RO) water in a 50mL falcon tube. The emulsion is sonicated for 5 minutes at 50% amplitude, 1 sec on and 0.2 sec off intervals using a Bandelin Sonoplus sonicator (TS113 probe). While cooling down the emulsion, 6.67g of sorbitol and 6.67g of glycerol are mixed with 996.2g of RO water in a 2L plastic beaker with a spatula. 4.73 g of cooled down emulsion is mixed into the plasticiser-water mix. The mixture is transferred to a Karlstein GrandPrix food processor, 20g of kappa-carrageenan is added and mixed at speed 7 at 30 °C for 30 minutes.

[0383] (ii) Film formation - kappa-carrageenan layer

[0384] The mixture is poured into a speed mixer container and degassed for 5 minutes at 1950rpm at 3 mbar. The mixture is immediately poured onto a flat glass plate having a Mylar® surface to cast a wet film, using a RK Print K303S multi coater with a Doctor Blade at speed 3. The film is then dried in the oven at 85 °C for 2-3 hours.

[0385] (iii) Preparation of alginate mixture

[0386] The mixture is prepared as described in Example 7, step (i) above.

[0387] (iv) Film formation - alginate layer

[0388] 25 ml of the mix produced in step (iii) is poured into a 50 ml Falcon tube. The mix is poured over the exposed surface (i.e. the surface not in contact with the glass plate) of the dried film from step (ii). The liquid is spread out uniformly over the plate using a doctor blade to give a wet film of the alginate mixture. The glass plate is then dried overnight at ambient temperature to form the dried film layer. (v) Preparation of starch mixture

[0389] The mixture is prepared as described in Example 7, step (iii) above.

[0390] (vi) Film formation - starch layer

[0391] 7 ml of the mix produced in step (v) is poured into a 50 ml Falcon tube. The mix is then further degassed by removing large bubbles with a pipette, before being allowed to cool to 55 °C and then spread over the exposed surface (i.e. the surface not in contact with the glass plate) of the dried film prepared in step (iv) using a Doctor blade to give a wet film. The plate is then put in the oven for 30 minutes at 80 °C to form a dried film.

[0392] The triple layer film is obtained by the peeling the dried film from the substrate.

[0393] Example 9 - Preparation of a starch - carrageenan - alginate film

[0394] A triple layer film comprising a first layer of alginate, and second layer of starch and a third layer of carrageenan is prepared. The first layer is formed first on a Mylar® substrate, followed by the third layer on top of the first layer and finally the second layer on top of the third layer as shown in Figure 1b.

[0395] (i) Preparation of alginate mixture

[0396] The mixture is prepared as described in Example 7, step (i) above.

[0397] (ii) Film formation - alginate layer

[0398] The film is prepared as described in Example 7, step (ii) above.

[0399] (iii) Preparation of kappa-carrageenan mixture

[0400] The mixture is prepared as described in Example 8, step (i) above.

[0401] (iv) Film formation - kappa-carrageenan layer

[0402] The mixture is poured into a speed mixer container and degassed for 5 minutes at 1950rpm at 3 mbar. The mixture is immediately poured over the exposed surface (i.e. the surface not in contact with the glass plate) of the dried film from step (ii) to cast a wet film, using a RK Print K303S multi coater with a Doctor Blade at speed 3. The film is then dried in the oven at 85 °C for 2-3 hours.

[0403] (v) Preparation of starch mixture

[0404] The mixture is prepared as described in Example 7, step (iii) above. (vi) Film formation - starch layer

[0405] 7 ml of the mix produced in step (v) is poured into a 50 ml Falcon tube. The mix is then further degassed by removing large bubbles with a pipette, before being allowed to cool to 55 °C and then spread over the exposed surface (i.e. the surface not in contact with the glass plate) of the dried film prepared in step (iv) using a Doctor blade to give a wet film. The plate is then put in the oven for 30 minutes at 80 °C to form a dried film.

[0406] The triple layer film is obtained by the peeling the dried film from the substrate.

[0407] Example 10 - Preparation of a starch - alginate - alkali-treated plant protein film

[0408] A triple layer film comprising a first layer of alginate, and second layer of starch and a third layer of alkali protein is prepared. The third layer is formed first on a Mylar® substrate, followed by the first layer on top of the third layer and finally the second layer on top of the first layer as shown in Figure 1c.

[0409] (i) Preparation of alkali-treated plant protein dispersion

[0410] 336g of pea protein isolate (PPI) is added to 2859g of room temperature reverse osmosis (RO) water and placed in a water bath at 90 °C. The mixture is stirred with an overhead stirrer with a propeller impeller at 1700 rpm for around 1 to 2 minutes to ensure homogeneous wetting of the PPI powder. 143.3g of 1M NaOH is added as a pH adjuster to the stirred mixture, a lid placed over the vessel and stirring continued for another 45 minutes. The temperature of the mixture is checked. If this is less than 85 °C stirring is continued until this temperature is reached.

[0411] The hot mixture is then transferred to a Silverson mixer and homogenised for 15 minutes at 8000 rpm. The vessel is then covered and left to cool until the mixture temperature is below 40 °C which may take several hours, typically overnight.

[0412] Once this temperature is reached the mixture is processed using a Pressure Cell Homogeniser SPCH-EP Model FPG12805 (Homogenising System Ltd) equipped with a piston gap valve with a 1 mm contact diameter (HPVS-1). The slurry is put through 2 passes at 100 MPa. 0.1 wt% Methyl paraben preservative is added. The pH of the mixture is 10.1. The slurry is stored in a fridge at 5°C until used.

[0413] 35 wt% plasticiser based upon total protein solids, preferably one or more of glycerol, sorbitol and propylene glycol, is added and mixed with an overhead stirrer for 5 minutes. (ii) Film formation - protein layer

[0414] A suitable quantity of the mixture of step (i) is poured at room temperature and then spread onto a flat glass plate having a Mylar® surface, to cast a wet film, using a RK Print K303S multi coater with a Doctor Blade at speed 3. Blade settings are carefully chosen by the skilled person, in order to give upon drying the desired dried- film thickness, which are reflected by the above-mentioned suitable quantity of the mixture as well as its wet thickness. The glass plate is then dried in the oven at 50°C to form a dried film.

[0415] (iii) Preparation of alginate mixture

[0416] The mixture is prepared as described in Example 7, step (i) above.

[0417] (iv) Film formation - alginate layer

[0418] The film is prepared as described in Example 8, step (iv) above.

[0419] (v) Preparation of starch mixture

[0420] The mixture is prepared as described in Example 7, step (iii) above.

[0421] (vi) Film formation - starch layer

[0422] The film is prepared as described in Example 8, step (vi) above.

[0423] The triple layer film is obtained by the peeling the dried film from the substrate.

[0424] Example 11 - Preparation of a pullulan - starch - carrageenan film

[0425] A triple layer film comprising a first layer of carrageenan, and second layer of starch and a third layer of pullulan is prepared. The first layer is formed first on a Mylar® substrate, followed by the second layer on top of the first layer and finally the third layer on top of the second layer as shown in Figure 1 a.

[0426] (i) Preparation of kappa-carrageenan mixture

[0427] The mixture is prepared as described in Example 8, step (i) above.

[0428] (ii) Film formation - kappa-Carrageenan layer

[0429] The film is prepared as described in Example 8, step (ii) above.

[0430] (iii) Preparation of starch mixture

[0431] The mixture is prepared as described in Example 7, step (iii) above. (iv) Film formation - starch layer

[0432] The film is prepared as described in Example 7, step (iv) above.

[0433] (v) Preparation of pullulan mixture

[0434] In a Klarstein Grand Prix food processor (500W power, 2.5 litre capacity) fitted with 4 standard stainless steel blades, while mixing at Speed 4, the following room temperature materials are added: reverse osmosis water, one or more plasticisers selected from glycerol, sorbitol or polyethylene glycol, and pullulan in the quantities and ratios understood by a skilled person. The food processor is set at a temperature of 85°C and left to mix for 60 minutes, whilst every 10 minutes scooping the material that accumulates on the walls back into the mixture. The mixture is then transferred to a Hauschild Speedmixer for 3 minutes at 50mBars and 1500 rpm and then left to cool to room temperature.

[0435] (vi) Film formation - pullulan layer

[0436] A suitable quantity of the mixture of step (v) is poured at room temperature and then spread over the exposed surface (i.e. the surface not in contact with the glass plate) of the dried film prepared in step (iv) using a RK Print K303S multi coater with a Doctor Blade. Blade settings are carefully chosen by the skilled person, in order to give upon drying the desired dried-film thickness, which are reflected by the above- mentioned suitable quantity of the mixture as well as its wet thickness. The glass plate is then dried in the oven at 50°C to form a dried film.

[0437] The triple layer film is obtained by the peeling the dried film from the substrate.

Claims

CLAIMS:

1. A film comprising: a first layer comprising: at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran; and one or more organic plasticisers; a second layer comprising: at least one material selected from plant-derived polysaccharides, wherein said plant- derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi- derived polysaccharide is pullulan, and agar; and one or more organic plasticisers; and a third layer, wherein the film contains less than 1 wt% of cations of calcium.

2. A film as claimed in claim 1 , wherein the at least one red algae- or brown algae- derived polysaccharide in the first layer is selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, and carrageenan, preferably wherein the at least one red algae- or brown algae-derived polysaccharide in the first layer is a salt of alginic acid wherein the counter ion of the salt is a monovalent ion.

3. A film as claimed in claim 1 or claim 2, wherein the first layer comprises at least one alkali metal salt of alginic acid, preferably lithium alginate, sodium alginate, potassium alginate, or mixtures thereof, more preferably sodium alginate.

4. A film as claimed in claim any one of claims 1 to 3, wherein the at least one material selected from plant-derived polysaccharides, fungi-derived polysaccharides and agar in the second layer is starch.

5. A film as claimed in any one of claims 1 to 4, comprising: a first layer comprising based on the total weight of the first layer: at least 20 wt.-% of one or more salts of alginic acid wherein the counter ion of the salt is a monovalent ion, and at least 5 wt.-% of one or more organic plasticisers; a second layer comprising based on the total weight of the second layer:at least one material selected from plant-derived polysaccharides, wherein said plant- derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi- derived polysaccharide is pullulan, and agar, and at least 5 wt.-% of one or more organic plasticisers; and a third layer, wherein the film contains less than 1 wt% of cations of calcium.

6. A film as claimed in claim 5, wherein the second layer comprises less than 20 wt.-% of alginic acid salts.

7. A film as claimed in any claim 5 or 6, wherein the organic plasticiser in the first layer is selected from glycerol, diglycerin, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethyl propane, poly ether polyols, 2-methyl-1,3-propanediol, ethanolamines, polyethylene glycol, propylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, oleic acid, monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, and mixtures thereof, preferably a mixture of glycerol, sorbitol and oleic acid.

8. A film as claimed in any one of claims 5 to 7, wherein the organic plasticiser in the second layer is selected from glycerol, diglycerin, polyethylene glycol, propylene glycol, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethyl propane, poly ether polyols, 2-methyl- 1 ,3-propanediol, ethanolamines, sorbitol, mannitol, xylitol, triethyl citrate, oleic acid, monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, and mixtures thereof, preferably a mixture of glycerol and sorbitol.

9. A film as claimed in any one of claims 5 to 8, wherein the third layer is the inner layer.

10. A film as claimed in claim 9, wherein the first layer is the outer layer and the second layer is the middle layer.

11. A film as claimed in claim 9 or claim 10, wherein the first layer comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, preferably sodium alginate.

12. A film as claimed in any one of claims 9 to 11 , wherein the second layer comprises starch.

13. A film as claimed in any one of claims 9 to 12, wherein the third layer comprises a third layer material which is a heat sealable compound, preferably wherein the heat sealable compound is selected from animal-derived proteins such as casein and gelatine, pullulan, polyvinyl alcohol, agar, and mixtures thereof.

14. A film as claimed in any one of claims 9 to 12, wherein the third layer comprises a third layer material which is a dispersibility enhancing compound, preferably wherein the dispersibility enhancing compound is selected from animal-derived proteins such as casein and gelatine, pullulan, polyvinyl alcohol, and plant-derived proteins such as alkali-treated plant protein, and mixtures thereof.

15. A film as claimed in any one of claims 9 to 14, wherein the third layer comprises polyvinyl alcohol.

16. A film as claimed in any one of claims 9 to 15, wherein the third layer is the inner layer and comprises polyvinyl alcohol, the first layer is the outer layer and comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, preferably sodium alginate, and the second layer is the middle layer and comprises starch.

17. A film as claimed in any one of claims 5 to 8, wherein the third layer is the middle layer.

18. A film as claimed in claim 17, wherein the first layer is the outer layer and the second layer is the inner layer.

19. A film as claimed in claim 17 or claim 18, wherein the first layer comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion.

20. A film as claimed in any one of claims 17 to 19, wherein the second layer comprises starch.

21. A film as claimed in any one of claims 17 to 20, wherein the third layer comprises a third layer material which is a dispersibility enhancing compound, preferably wherein the dispersibility-enhancing compound is selected from animal-derived proteins suchas casein and gelatine, pullulan, polyvinyl alcohol, plant-derived proteins such as alkali-treated plant protein, and carrageenan mixtures thereof.

22. A film as claimed in any one of claims 5 to 8, wherein the third layer is the outer layer.

23. A film as claimed in claim 22, wherein the first layer is the middle layer and the second layer is the inner layer.

24. A film as claimed in claim 22 or claim 23, wherein the first layer comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion.

25. A film as claimed in any one of claims 22 to 24, wherein the second layer comprises starch.

26. A film as claimed in any one of claims 22 to 25, wherein the third layer comprises a third layer material which is a strengthening compound, preferably wherein the strengthening compound is carrageenan or a plant-derived protein such as alkali- treated plant protein, preferably carrageenan.

27. A film as claimed in any one of claims 22 to 26, wherein the third layer comprises a plant-derived protein such as alkali-treated plant protein.

28. A film as claimed in any one of claims 22 to 27, wherein the second layer is the inner layer and comprises starch, the first layer is the middle layer and comprises a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, preferably sodium alginate, and the third layer is the outer layer and comprises a plant-derived protein such as alkali-treated plant protein.

29. A film as claimed in any one of claims 1 to 28, wherein the film has a thickness of between 20 pm and 120 pm.

30. A process for preparing a film as claimed in any one of claims 1 to 29, comprising the steps of:(i) providing a first layer comprising at least one red algae- or brown algae- derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran, and one or more organic plasticisers;(ii) providing a second layer comprising at least one material selected from plant- derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar, and one or more organic plasticisers;(iii) providing a third layer; and(iv) forming said first layer, said second layer and said third layer into said film, wherein the film contains less than 1 wt% of cations of calcium.

31. A process as claimed in claim 30, comprising the steps of:(a) mixing the at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran and the at least one organic plasticiser in water to form a mixture (a);(b) forming the mixture (a) into said first layer on a surface;(c) mixing the at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar and the at least one organic plasticiser in water to form a mixture (b);(d) forming the mixture (b) into said second layer on said first layer; and(e) providing a third layer on said second layer.

32. A process as claimed in in claim 30, comprising the steps of:(a) providing a third layer on a surface;(b) mixing the at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran and the at least one organic plasticiser in water to form a mixture (d);(c) forming the mixture (d) into said first layer on said third layer;(d) mixing the at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar and the at least one organic plasticiser in water to form a mixture (e); and(e) forming the mixture (e) into said second layer on said first layer.

33. A process as claimed in in claim 30, comprising the steps of:(a) mixing the at least one red algae- or brown algae-derived polysaccharide selected from a salt of alginic acid wherein the counter ion of the salt is a monovalent ion, carrageenan, and furcellaran and the at least one organic plasticiser in water to form a mixture (g);(b) forming the mixture (g) into said first layer on a surface;(c) providing a third layer on said first layer;(d) mixing the at least one material selected from plant-derived polysaccharides, wherein said plant-derived polysaccharide is a starch, fungi-derived polysaccharides, wherein said fungi-derived polysaccharide is pullulan, and agar and the at least one organic plasticiser in water to form a mixture (h); and(e) forming the mixture (h) into said second layer on said third layer.

34. A product enclosed by a film according to any one of claims 1 to 29.

35. A product as claimed in claim 34, which is a foodstuff, a pharmaceutical product, a cleaning product, an agricultural product (e.g. an animal feed or medication), a chemical product or a cosmetic product.

36. A method of enclosing a product, comprising the steps of:(i) wrapping the product in a film as claimed in any one of claims 1 to 29; and(ii) heat sealing the film around the product to form a sachet.

37. A sachet prepared by the method of claim 36.

38. Use of a film as claimed in any one of claims 1 to 29 to enclose a product and / or to prepare a sachet.

39. A method of releasing a product enclosed in a film as claimed in any one of claims 1 to 29, comprising the steps of:(i) placing the enclosed product in water; and(ii) allowing the film to disperse, thereby releasing the product.

Images