Plant Protein-Starch Film

Abstract

The present invention relates to a film comprising a combination of vegetable protein and starch in an amount of 50 wt% or more based on the total weight of the film at 55% relative humidity and 22°C, wherein the mass ratio of starch to vegetable protein is in the range of 0.5:1 to 30:1, and the vegetable protein has been pretreated with an organic acid.

Description

[Technical field]

[0001] The present invention relates to films comprising vegetable proteins and starches, and methods for preparing the films. The present invention also relates to uses of the films and methods related to the films, including coating or encapsulating products. The present invention also relates to film-forming compositions and films obtained therefrom. [Background technology]

[0002] There is an increasingly urgent need to reduce the environmental impact of many everyday activities and to reduce the amount of non-renewable resources involved in these activities. One example of this is the increased use of biodegradable packaging to replace traditional plastics such as polyethylene and polypropylene (e.g., edible films used in food packaging). Starches are particularly useful materials due to their renewable resource and low cost.

[0003] In this regard, the development of water-soluble / water-dispersible films has been of particular interest, and starch has been found to be a very useful material for this purpose.However, the mechanical properties of starch films depend on the humidity and temperature conditions of the surroundings.This makes the scale-up of production more complicated, and narrows the window of use when used to package consumer products.In addition, starch films tend to have low tensile strength, which means that they can be brittle, thereby limiting their usefulness as packaging films.

[0004] A particular problem with starch-based films is that starch is sensitive to low temperatures due to retrogradation.Food packaging can often be subjected to low temperatures when packaged food is stored in refrigerators.This means that it has not been possible to develop a commercially available film that contains a large amount of starch that is robust enough to withstand all the conditions that may be required for food packaging.However, the low cost and easy availability of starch means that it is still a desirable material to incorporate into such films. Summary of the Invention [Problem to be solved by the invention]

[0005] Thus, there is a need to develop starch-based water-soluble / water-dispersible films that have sufficiently robust mechanical properties for use as packaging films, including the ability to withstand handling during the manufacturing process, transportation and storage at low temperatures. A preferred feature of food packaging is that it is edible, thus further minimizing waste and increasing consumer convenience. [Means for solving the problem]

[0006] In view of the first aspect, the present invention provides a film comprising a combination of vegetable protein and starch at 55% relative humidity and 22°C, at 50 wt% or more based on the total mass of the film, wherein the mass ratio of starch to vegetable protein is in the range of 0.5:1 to 30:1, and the vegetable protein is pretreated with an organic acid.

[0007] Preferably, the film of the first aspect of the invention comprises: a first layer comprising starch; a second layer comprising a vegetable protein, the vegetable protein being pretreated with an organic acid; and Including, The second layer is in contact with the first surface of the first layer.

[0008] Viewed from a further aspect, the present invention relates to a method for preparing a film as described hereinabove, comprising the steps of: (i) mixing starch in water, optionally with sonication, to form a starch mixture; (ii) dissolving the plant protein in water and an organic acid, optionally using sonication, to form a protein solution; (iii) mixing the starch mixture and the protein solution to form a film-forming composition; (iv) forming the film-forming composition into a film at 55% relative humidity and 22° C., the film comprising at least 50 wt % of a combination of vegetable protein and starch, based on the total weight of the film; The present invention provides a method comprising:

[0009] Viewed from a further aspect, the present invention relates to a method for preparing a film as described hereinabove, comprising the steps of: (i) mixing starch in water, optionally with sonication, to form a starch mixture; (ii) forming the starch mixture into a first layer on a surface; (iii) dissolving the plant protein in water and an organic acid, optionally using sonication, to form a protein solution; (iv) forming a protein solution into a second layer on the first surface of the first layer, such that the resulting film comprises at least 50 wt. % of a combination of starch and vegetable protein based on the total weight of the film at 55% relative humidity and 22° C.; The present invention provides a method comprising:

[0010] Viewed from a further aspect, the present invention provides a product, preferably a food product, coated or encapsulated with a film as described herein above.

[0011] Viewed from a further aspect, the present invention relates to a method for coating or encapsulating a product, preferably a food product, comprising the steps of: (i) packaging the product in a film as described herein above; (ii) sealing a film around the product; The present invention provides a method comprising:

[0012] Viewed from a further aspect, the present invention provides the use of a film as described hereinabove for coating or encapsulating a product, preferably a food product.

[0013] The method for releasing a product coated or encapsulated with a film as described herein above comprises the steps of: (i) placing the coated or encapsulated product in water; (ii) dispersing the film, thereby releasing the product; Includes.

[0014] Viewed from a further aspect, the present invention provides a film-forming composition comprising a vegetable protein and a starch, wherein the mass ratio of vegetable protein to starch is in the range of 0.5:1 to 30:1, and the vegetable protein has been pretreated with an organic acid.

[0015] Viewed from a further aspect, the present invention provides a film obtained from a film-forming composition as described herein above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention describes a film that is robust and water dispersible. Thus, the film of the present invention has the strength to withstand the manufacturing process and subsequent transportation and storage, but can then disperse upon contact with water, for example, releasing the packaged product, making it useful as a packaging material. Thus, the present invention provides a film comprising a combination of vegetable protein and starch at 50 wt% or more based on the total weight of the film at 55% relative humidity and 22°C, the weight ratio of starch to vegetable protein being in the range of 0.5:1 to 30:1, and the vegetable protein being pretreated with an organic acid.

[0017] In the film of the present invention, the mass ratio of starch to vegetable protein ranges from 0.5:1 to 30:1.

[0018] In preferred films of the invention, the weight ratio of starch to vegetable protein ranges from 2:1 to 27.5:1, more preferably from 5:1 to 25:1, and even more preferably from 0.7:1 to 25:1. Combinations of low levels of vegetable protein and starch in these weight ratio ranges have been found to increase the strength of the film without negatively affecting the ability of the film to disperse in water.

[0019] In another preferred film of the present invention, the mass ratio of starch to vegetable protein ranges from 1:2 to 3:1, more preferably from 1:1 to 2:1. It has been found that combinations of vegetable protein and starch in these mass ratio ranges result in surprisingly robust films.

[0020] To determine the total protein content in a given sample of film, the contained soluble nitrogen fraction can be quantitatively measured according to the Kjeldahl method, and then the total protein content can be obtained by multiplying the nitrogen content, expressed as a percentage by mass of the dry product, by a factor of 6.25, a method well known to those skilled in the art.

[0021] The total starch content in a given sample of film can be determined by standard methods AOAC Method 996.11 or AOAC Method 2014.10, which use the combined action of α-amylase and amyloglucosidase to hydrolyze starch to glucose, followed by glucose determination with a glucose oxidase / peroxidase reagent.

[0022] A preferred film of the present invention is a monolayer film, an example of which is graphically depicted in Figure 1a.

[0023] Another preferred film of the present invention is a multilayer film. Thus, a preferred film of the present invention is a first layer comprising starch; a second layer comprising a vegetable protein, the vegetable protein being pretreated with an organic acid; and Including, a second layer in contact with the first surface of the first layer, the film comprising at least 50 wt % of a combination of vegetable protein and starch based on the total weight of the film at 55% relative humidity and 22° C.; The mass ratio of starch to plant protein ranges from 0.5:1 to 30:1.

[0024] An example of such a multilayer film is graphically depicted in FIG. 1b, where layer (1) is the first layer and layer (2) is the second layer.

[0025] In a preferred film of the present invention, the first layer further comprises a vegetable protein, which is pretreated with an organic acid.

[0026] In preferred films of the present invention, the second layer further comprises starch.

[0027] In the preferred film of the present invention, the first layer further comprises a vegetable protein, the vegetable protein being pretreated with organic acid, and the second layer further comprises a starch.As will be understood by those skilled in the art, the mass ratio of starch to vegetable protein in each of the first and second layers can be the same or different.Preferably, the mass ratio of starch to vegetable protein in each of the first and second layers is different.More preferably, the mass ratio of starch to vegetable protein in the first layer is greater than the mass ratio of starch to vegetable protein in the second layer.

[0028] As will be appreciated by those skilled in the art, additional layers may be added to the films of the present invention.

[0029] The film of the present invention comprises a vegetable protein. In a preferred film of the present invention, the vegetable protein is selected from soy protein, pea protein, rice protein, potato protein, rapeseed protein and / or sunflower protein, preferably selected from pea protein, potato protein, rapeseed protein, sunflower protein and / or rice protein, more preferably pea protein.

[0030] In a preferred film of the present invention, the vegetable protein is a protein from the Fabaceae family, preferably pea protein.

[0031] Preferred films of the present invention are free of soy protein and / or gluten.

[0032] In a preferred film of the present invention, the vegetable protein source is a vegetable protein isolate, preferably a pea protein isolate.

[0033] In a preferred film of the present invention, the vegetable protein source is vegetable flour, preferably pea flour.

[0034] In preferred films of the present invention, the vegetable protein source is obtained from waste streams, for example waste streams from the agriculture or food industries.

[0035] A preferred film of the present invention comprises 2.0 to 40 wt %, preferably 2.5 to 35 wt %, more preferably 3.0 to 30 wt % of vegetable protein based on the total weight of the film at 55% relative humidity and 22°C.

[0036] The organic acid is an organic compound having acidic properties, preferably a carboxylic acid. In the preferred film of the present invention, the organic acid used for pretreatment of the vegetable protein is selected from acetic acid, alpha-hydroxy acid, or beta-hydroxy acid. More preferably, the organic acid is selected from acetic acid, lactic acid, citric acid, malic acid, maleic acid, glycolic acid, gluconic acid, tartaric acid, beta-hydroxypropionic acid, beta-hydroxybutyric acid, beta-hydroxybeta-methylbutyric acid, 2-hydroxybenzoic acid, and carnitine, or a mixture thereof, preferably acetic acid.

[0037] In preferred films of the present invention, the organic acid used to pre-treat the vegetable protein is a volatile organic acid (i.e., one that has a boiling point below 120° C.), preferably acetic acid, because volatile organic acids can be easily removed from the film-forming composition during the casting or drying process such that the final film contains little, if any, residual organic acid.

[0038] The films of the present invention show a useful combination of properties, which means that they are robust, but still dispersible in water.Without wishing to be bound by theory, it is believed that the increased strength of the films of the present invention can be attributed to the pretreatment of vegetable protein with organic acid.This is believed to be because vegetable protein unfolds in the presence of organic acid at high temperature, making it more accessible to interact with existing starch, for example, via hydrogen bonding.The increase in these protein-starch interactions reduces the level of starch retrogradation, which is the cause of the brittleness of conventional starch-based films.

[0039] Pretreatment of the plant protein with an organic acid results in a plant protein having a protein secondary structure having at least 40% intermolecular β-sheets, at least 50% intermolecular β-sheets, at least 60% intermolecular β-sheets, at least 70% intermolecular β-sheets, at least 80% intermolecular β-sheets, or at least 90% intermolecular β-sheets.

[0040] For the avoidance of doubt, pre-treatment of the vegetable protein with organic acid is carried out prior to combining the vegetable protein with starch.

[0041] Preferably, the pretreatment of the plant protein with organic acids comprises the use of an aqueous solution of organic acids. More preferably, the aqueous solution of organic acids has a concentration of at least 5% (v / v), preferably at least 10% (v / v), more preferably at least 15% (v / v), more preferably at least 20% (v / v), more preferably at least 25% (v / v), more preferably at least 30% (v / v), more preferably at least 40% (v / v), even more preferably at least 50% (v / v). Alternatively, the aqueous solution of organic acids has a concentration of 90% (v / v) or less, preferably 80% (v / v) or less, more preferably 70% (v / v) or less. Concentrated acid solutions are dangerous to handle on a large scale.

[0042] Starch is a carbohydrate polymer. Starch consists essentially of amylose and / or amylopectin, and in its native form is typically in the form of semi-crystalline granules. Starch sources include, but are not limited to, fruits, seeds, and roots or tubers of plants.

[0043] Some starches are classified as waxy starches, which consist essentially of amylopectin and do not contain any appreciable amount of amylose. Exemplary waxy starches include waxy maize starch, waxy rice starch, waxy potato starch, and waxy wheat starch.

[0044] Alternatively, some starches are classified as high amylose starches.

[0045] Modified starches are prepared by treating native starch physically, enzymatically, or chemically to change its properties. Starch can be modified, for example, enzymatically, by heat treatment, oxidation, or by reaction with various chemicals.

[0046] In the films of the present invention, the starch can be a native starch or a modified starch, or a mixture thereof.

[0047] In preferred films of the 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, soybean starch, or mixtures thereof, preferably potato starch.

[0048] In another preferred film of the present invention, the starch is selected from acid treated starch, dextrin, alkali modified starch, bleached starch, oxidized starch, enzyme treated starch, maltodextrin, cyclodextrin monostarch phosphate, distarch phosphate, acetylated starch, hydroxypropylated starch, hydroxyethyl starch, sodium starch octenyl succinate, aluminum starch octenyl succinate or cationic starch, or mixtures thereof, preferably acid treated starch.

[0049] Preferred films of the present invention contain 30-70 wt %, preferably 40-65 wt %, more preferably 45-60 wt % starch based on the total weight of the film at 55% relative humidity and 22°C.

[0050] Preferred films of the present invention comprise at least 50 wt. % vegetable protein and starch combination, preferably at least 55 wt. %, more preferably at least 60 wt. %, based on the total weight of the film at 55% relative humidity and 22°C.

[0051] Preferred films of the present invention comprise no more than 75 wt. % of a combination of vegetable protein and starch, preferably no more than 72 wt. %, more preferably no more than 70 wt. %, based on the total weight of the film at 55% relative humidity and 22°C.

[0052] A preferred film of the present invention comprises 50-75 wt.%, preferably 55%-72 wt.%, more preferably 60-70 wt.% of a vegetable protein and starch combination based on the total weight of the film at 55% relative humidity and 22°C.

[0053] Preferred films of the invention contain 8-20 wt % water, preferably 10-15 wt %, based on the total weight of the film at 55% relative humidity and 22°C.

[0054] The preferred film of the present invention further comprises a plasticizer. The plasticizer is useful for improving film flexibility. Preferably, the plasticizer is selected from glycerol, polyethylene glycol, propylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, fatty acids, glucose, mannose, fructose, sucrose, urea, lecithin, wax, amino acids and organic acids (e.g. lactic acid, citric acid, glycolic acid, malic acid, gluconic acid or tartaric acid), or mixtures thereof, preferably glycerol.

[0055] As one skilled in the art will appreciate, organic acids may be used to pre-treat the vegetable protein and then remain to subsequently function as plasticizers in the resulting film.

[0056] If the film is intended for packaging food, the plasticizer must be suitable for human consumption. The preferred plasticizers mentioned above are all suitable for human consumption (i.e., they are food grade materials).

[0057] Preferred films of the invention contain 5-30 wt %, preferably 10-25 wt %, more preferably 10-20 wt %, and most preferably 13-19 wt % plasticizer based on the total weight of the film at 55% relative humidity and 22°C.

[0058] Preferred films of the present invention further comprise a pigment or dye, preferably selected from azo, quinophthalone, triphenylmethane, xanthene or indigoid dyes, iron oxides or hydroxides, titanium dioxide, or natural dyes, and mixtures thereof. Examples include Patent Blue V, Acid Brilliant Green BS, Red 2G, Azorubine, Ponceau 4R, Amaranth, D+C Red 33, D+C Red 22, D+C Red 26, D+C Red 28, D+C Yellow 10, Yellow 2 G, FD+C Yellow 5, FD+C Yellow 6, FD+C Red 3, FD+C Red 40, FD+C Blue 1, FD+C Blue 2, FD+C Green 3, Brilliant Black BN, Carbon Black, Iron Oxide Black, Iron Oxide Red, Iron Oxide Yellow, Titanium Dioxide, Riboflavin, Carotene, Anthocyanins, Turmeric, Cochineal Extract, Chlorophyllin, Canthaxanthin, Caramel, Betaine and Candurin® Pearlescent Pigments. More preferably, the pigment or dye is a food colorant, preferably a food colorant derived from a vegetable source, more preferably a food colorant selected from carotenoids, chlorophyllin, anthocyanins and betanins.

[0059] The preferred film of the present invention further comprises a structural agent. The use of the structural agent can help improve the strength of the film. Preferably, the structural agent is selected from microcrystalline cellulose, microfibrillated cellulose containing cellulose fibers extracted from citrus fruit pulp, cellulosic materials containing fine fibrous cellulose from fermentation, starch microcrystals, clays, or mixtures thereof, preferably microfibrillated cellulose from citrus pulp.

[0060] A preferred film of the present invention contains 0.5 to 5 wt %, preferably 0.6 to 2.5 wt %, of said structure enhancing agent based on the total weight of the film at 55% relative humidity and 22°C.

[0061] The preferred film of the present invention further comprises a hydrophobic agent.Preferably, the hydrophobic agent is a plant-based oil, preferably a non-volatile plant-based oil, preferably a vegetable oil, preferably selected from vegetable oil, rapeseed oil, canola oil, soybean oil, sunflower oil, safflower oil, corn oil, and flavored oil, or a mixture thereof.Examples of flavored oils include thyme oil, basil oil, olive oil, chili oil, rosemary oil, garlic oil, citrus oil, or lavender oil.

[0062] Alternatively, the hydrophobic agent is a plant-based fatty acid, which is a saturated or unsaturated fatty acid, or a mixture thereof.Preferably, the plant-based fatty acid is non-volatile.Preferred saturated fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid.Preferred unsaturated fatty acids include myristoleic acid, palmitoleic acid, oleic acid, and linoleic acid.

[0063] Without wishing to be bound by theory, it is believed that the presence of a hydrophobic agent, such as a vegetable-based oil or vegetable-based fatty acid, in the film of the present invention improves the surface integrity of the film. This is believed to be because, during the preparation of the film, the hydrophobic agent migrates to the top surface of the cast composition, thereby inhibiting the premature formation of a skin thereon, which means that steam can escape more easily and, once dry, fewer air bubbles are formed and entrapped within the film.

[0064] The use of flavored oils as the hydrophobic agent in the films of the present invention provides the added advantage that the film itself can act as a flavor delivery vehicle, for example when the film is used to package food products.

[0065] Preferred films of the present invention contain 0.3-2.5 wt %, preferably 0.6-2.0 wt %, more preferably 0.7-1.5 wt % of hydrophobic agent based on the total weight of the film at 55% relative humidity and 22°C.

[0066] Preferred films of the present invention are suitable for human or animal consumption, i.e., the films are edible films. More preferably, the films of the present invention do not contain ingredients derived from animal sources, making them suitable for consumption by vegetarians / vegans.

[0067] Preferred films of the present invention are digestible.

[0068] Edible, as used herein, refers to a film that is digestible and provides some nutritional benefit on its own. This is in contrast to a film that is safe to eat but does not provide nutrition on its own. An example of these latter films is a film made from HPMC, hydroxypropyl methylcellulose, or other cellulose-based films, which are widely used in the pharmaceutical industry. A characteristic of edible films is that they are inherently very rapidly biodegradable. Starch is often chemically modified to improve its cross-linking ability. Although such techniques can be very effective in improving the physical properties of starch, this very often reduces its digestibility and use as an edible material. Therefore, it is preferred that the starch used in these films has not been subjected to prior chemical processing other than hydrolysis.

[0069] Preferred films of the present invention do not contain chitosan.

[0070] The film of the present invention has high dispersibility in water. This means that the film of the present invention can be used as a packaging material for products that do not generate waste during the final use of the product. For example, the film of the present invention can be used to package detergent, and the film can disperse in water to release the detergent during the washing process. Alternatively, the film of the present invention can be used to package food, and the film can disperse in water to release the food during the cooking process. Thus, in the preferred film of the present invention, when 0.2g of the film is boiled in water for 3 minutes while stirring, and then poured through a 2mm mesh sieve, no more than 0.15g, preferably no more than 0.1g, more preferably no more than 0.05g of residue is collected on the sieve. Advantageously, the residue is completely biodegradable, and this means that the film has no negative impact on the environment.

[0071] In preferred films of the invention, the pH of a dispersion of the film at a concentration of 1 g film in 10 g deionized water at 25° C. is greater than 5, preferably greater than 5.5, more preferably greater than 6. This has the advantage that when the film is used to package food products, the film, once dispersed, does not impart a sour or other negative flavor to the food product.

[0072] In the preferred films of the present invention, the viscosity of a dispersion of the film at a concentration of 1 g of film in 50 g of deionized water is -1 less than 100cps at 25℃ and 10s -1 less than 90cps at 25°C and 10s, -1 This has the advantage that the film, once dispersed, does not negatively affect the viscosity of the product, e.g., if the packaged product is a beverage, the dispersed film will not unduly thicken the beverage and cause a negative consumer experience.

[0073] In preferred films of the invention, the film has a tensile strength of 0.15 to 5 MPa, preferably 0.17 to 3.5 MPa, measured according to ASTM D882-18 at 76% relative humidity and 5°C.

[0074] In preferred films of the present invention, the film has a breaking strain, measured by ASTM D882-18 at 76% relative humidity and 5°C, of ​​10 to 150%, preferably 15 to 120%.

[0075] In preferred films of the invention, the plant protein in the second layer has a secondary structure with at least 40% intermolecular β-sheet content, at least 50% intermolecular β-sheet content, at least 60% intermolecular β-sheet content, at least 70% intermolecular β-sheet content, at least 80% intermolecular β-sheet content, or at least 90% intermolecular β-sheet content as measured by FTIR when the second layer is prepared on an inert surface, such as a glass surface.

[0076] To investigate the secondary structure of the plant proteins in the second layer, Fourier transform infrared (FTIR) analysis was performed. FTIR spectroscopic data were collected using a FTIR VERTEX 70 spectrometer (Bruker) with a diamond attenuated total reflectance (ATR) element. The second layer containing the plant proteins should be in direct contact with the diamond ATR cell. Data were collected using 128 scans at 4 cm-1 resolution with background subtraction. For protein structural analysis, the spectra were smoothed and normalized with second-order and seven-point window Savitzky-Golay filters. The second derivative of the amide I band (1600-1700 cm-1) was calculated from the smoothed data and deconvoluted to quantify the secondary and quaternary structural contributions. In preferred films of the present invention, the biodegradation percentage of the film after 28 days with respect to O2 consumption, measured according to ISO-14851, is 70-100%, more preferably 80-100%, and even more preferably 85-100%.

[0077] In preferred films of the present invention, the percentage biodegradation of the film with respect to CO2 production after 28 days, measured according to ISO-5 14851, is 70-100%, more preferably 75-100%, even more preferably 80-100%.

[0078] The present invention also relates to a film comprising vegetable protein and starch, wherein the mass ratio of starch to vegetable protein is in the range of 0.5:1 to 30:1, and the film has a tensile strength of 0.15 to 5 MPa as measured by ASTM D882-18 at 76% relative humidity and 5°C and / or a breaking strain of 10 to 150% as measured by ASTM D882-18 at 76% relative humidity and 5°C.

[0079] Preferred characteristics of the film are as described above.

[0080] The present invention also relates to a method for preparing a film as described herein above, comprising the steps of: (i) mixing starch in water, optionally with sonication, to form a starch mixture; (ii) dissolving the plant protein in water and an organic acid, optionally using sonication, to form a protein solution; (iii) mixing the starch mixture and the protein solution to form a film-forming composition; (iv) forming the film-forming composition into a film comprising at least 50 wt. % of a combination of starch and vegetable protein, based on the total weight of the film, at a relative humidity of 55% and 22° C., wherein the weight ratio of starch to vegetable protein is in the range of 0.5:1 to 30:1; The present invention provides a method comprising:

[0081] In step (i), sonication inherently heats the solution due to the applied sonic energy.

[0082] In a preferred process of the present invention, the mixing step (i) is carried out at a temperature in the range of 70-100°C, preferably 85-95°C.

[0083] In a preferred method of the present invention, the dissolving step (ii) is carried out at a temperature in the range of 70-100°C, preferably 85-95°C.

[0084] In a preferred process of the invention, the organic acid is removed between steps (ii) and (iii).

[0085] In a preferred process of the present invention, the mixing step (iii) is carried out at a temperature in the range of 70 to 100°C, preferably 85 to 95°C.

[0086] In a preferred method of the present invention, steps (i), (ii) or (iii) further comprise sonication and / or ultrasound treatment.

[0087] In a preferred method of the invention, step (iv) comprises casting the film-forming composition onto a surface. Preferably, the surface is a preformed layer comprising starch or a preformed layer comprising vegetable protein. Alternatively, the surface is a glass plate or other backing material, such as a PET carrier film. Alternatively, the surface is a moving belt, preferably a moving steel belt.

[0088] In a preferred process of the invention, in step (iv) the film-forming composition is at a temperature in the range of from 50 to 95°C, more preferably from 50 to 85°C.

[0089] In a preferred method of the invention the surface is heated. Preferably the surface is heated to a temperature in the range of 50 to 130°C, more preferably 55 to 100°C.

[0090] In a preferred process of the invention, step (iv) further comprises heating the film in an oven, preferably at a temperature in the range of from 70 to 150°C.

[0091] In another preferred method of the present invention, step (iv) comprises extruding the film-forming composition through an orifice to form a film.

[0092] A preferred method of the present invention further comprises an ageing step. Preferably, said ageing step comprises subjecting the film to a temperature between 10 and 35° C. for a period of one week.

[0093] In a preferred method of the invention, steps (i)-(iv) are repeated to produce a multilayer film. Thus, steps (i)-(iv) can be performed to produce a first layer, and then steps (i)-(iv) can be repeated to produce a second layer on a first surface of the first layer.

[0094] The present invention also relates to a method for preparing a film as described herein above, comprising the steps of: (i) mixing starch in water, optionally with sonication, to form a starch mixture; (ii) forming the starch mixture into a first layer on a surface; (iii) dissolving the plant protein in water and an organic acid, optionally using sonication, to form a protein solution; (iv) forming a protein solution into a second layer on the first surface of the first layer, such that the resulting film comprises at least 50 wt. % of a combination of vegetable protein and starch based on the total weight of the film at 55% relative humidity and 22° C., and the weight ratio of starch to vegetable protein is in the range of 0.5:1 to 30:1; The present invention provides a method comprising:

[0095] In step (i), sonication inherently heats the solution due to the applied sonic energy.

[0096] In a preferred process of the present invention, the mixing step (i) is carried out at a temperature in the range of 70-100°C, preferably 85-95°C.

[0097] In a preferred method of the present invention, step (i) further comprises sonication and / or ultrasound treatment.

[0098] In a preferred method of the invention, step (ii) comprises casting the starch mixture onto a surface. Preferably, the surface is a preformed layer comprising starch or a preformed layer comprising vegetable protein. Alternatively, the surface is a glass plate or other backing material, such as a PET carrier film. Alternatively, the surface is a moving belt, preferably a moving steel belt.

[0099] In a preferred process of the invention, in step (ii) the starch mixture is at a temperature in the range of 50 to 95°C, preferably 50 to 85°C.

[0100] In a preferred method of the invention the surface is heated. Preferably the surface is heated to a temperature in the range of 50 to 130°C, more preferably 55 to 100°C.

[0101] In a preferred method of the present invention, the dissolving step (ii) is carried out at a temperature in the range of 70-100°C, preferably 85-95°C.

[0102] In a preferred method of the present invention, step (iii) further comprises sonication and / or ultrasound treatment.

[0103] In a preferred process of the invention, the organic acid is removed between steps (iii) and (iv).

[0104] In a preferred method of the invention, step (iv) comprises casting the protein solution onto the first surface of the first layer. Preferably, the first surface of the first layer is heated to a temperature in the range of 50 to 95°C, more preferably 55 to 85°C.

[0105] In a preferred method of the invention, in step (iv) the protein solution is at a temperature in the range of 50 to 100°C, preferably 55 to 90°C.

[0106] The present invention also provides a product, preferably a food product, coated or encapsulated with a film as described herein above.

[0107] Preferably, the product is a food product, a pharmaceutical product, a cleaning product, an agricultural product (eg, animal feed) or a pharmaceutical product, a chemical product, or a cosmetic product.

[0108] Preferably, the product is a solid product, a powder product, or a liquid product with a water activity of less than 50%.

[0109] The water activity of a material is the % equilibrium relative humidity of the material divided by 100. The % equilibrium relative humidity of a sample is measured by use of a humidity probe. Suitable equipment includes a Rotronics HC2-AW unit manufactured by Process Sensing Technologies, operated in accordance with instructions dated 03 / 31 / 2016 or later. The unit should have been calibrated within one year of use according to the procedure using salt solutions as specified in the operating instructions. The test sample is placed in a sample cup and placed in the test unit. A humidity cell is then placed in the sample cup to seal the sample in the sample cup. The free water in the test sample is then allowed to equilibrate with the air in the headspace above the sample, and the final humidity level in the headspace is measured by the HC2 unit and reported as % equilibrium relative humidity (eRH) at the test temperature. The %eRH is then divided by 100 to obtain the water activity of the sample. To avoid temperature dependent variations, measurements should be performed at temperatures between 20°C and 25°C.

[0110] Preferably, the product is a solid product selected from a soup or flavour preparation (e.g. a soup stock bar), a personal detergent (e.g. a soap bar, a body wash, a body scrub or a shampoo), a laundry detergent tablet or a dishwasher detergent tablet. More preferably, the product is a soup stock bar. Alternatively, the product is a laundry detergent tablet or a dishwasher detergent tablet.

[0111] Preferably, the product is a powder product selected from powdered food, powdered drink, milk powder, powdered soup, powdered hot chocolate, powdered coffee, soup flakes, and powdered shampoo. More preferably, the product is a powdered drink.

[0112] Preferably, the product is a non-aqueous liquid product that is an oil or a hair care product. More preferably, the product is a cooking oil.

[0113] The present invention also provides a method for coating or encapsulating a product, preferably a food product, comprising the steps of: (i) packaging the product in a film as described herein above; (ii) sealing a film around the product; The present invention provides a method comprising:

[0114] Preferred products are as described above.

[0115] Preferably, step (ii) comprises heat sealing.

[0116] As those skilled in the art will understand, the sealing process requires contact between sections of the film containing starch. For example, a composite film containing starch and vegetable protein can be sealed to another composite film containing starch and vegetable protein, or to itself. However, if the film is a multi-layer film, for example, containing a starch layer and a vegetable protein layer, the starch layer needs to be sealed to another film containing starch, or to itself. This is because starch can melt (or gelatinize) at a much lower temperature compared to vegetable protein. Residual water present in the starch layer also helps to lower the melting (or gelatinization) temperature of starch.

[0117] The present invention also provides the use of a film as described herein above for coating or encapsulating a product, preferably a food product.

[0118] Preferred products are as described above.

[0119] The present invention also relates to a method for releasing a product coated or encapsulated with a film as described herein above, comprising the steps of: (i) placing the coated or encapsulated product in water; (ii) dispersing the film, thereby releasing the product; The present invention provides a method comprising:

[0120] Preferred products are as described above.

[0121] Preferably, the product is released during the cooking process.

[0122] Alternatively, the product is released during the cleaning process.

[0123] In a preferred process of the invention, step (ii) further comprises stirring or shaking.

[0124] The present invention also provides a film-forming composition comprising a vegetable protein and a starch, wherein the mass ratio of starch to vegetable protein is in the range of 0.5:1 to 30:1, and the vegetable protein is pretreated with an organic acid.

[0125] Preferred features are as described above in connection with the films of the invention.

[0126] The present invention also provides a film obtained from the film-forming composition as described hereinabove.

[0127] Preferred features are as described above. [Brief description of the drawings]

[0128] [Figure 1a] 1 is a graphical representation of a monolayer film of the present invention. [Figure 1b]1 is a graphical representation of a multilayer film of the present invention. [Diagram 2] 1 is a photograph of a portion of the film of Example 1 laid over printed text to demonstrate the transparency of the film. [Figure 3a] 3 is a photograph of the product packaged and sealed in film E4 of Example 1. FIG 3a shows a soup block. [Figure 3b] Photograph of the product packaged and sealed in film E4 of Example 1. Figure 3b shows a soap bar. [Figure 3c] Photograph of product packaged and sealed in film E4 of Example 1. Figure 3c shows a dishwasher tablet. EXAMPLES

[0129] material Pea protein isolate (PPI) (80 wt% protein, 4 wt% carbohydrate) (ProEarth P16109) was purchased from Cambridge Commodities Ltd. Lactic acid (food grade, ≧80%) was purchased from Cambridge Commodities Ltd. Acetic acid (glacial, food grade) was purchased from Fisher Scientific. Soluble potato starch was purchased from APC Ltd, East Tame Business Park, Cheshire SK14 4GX, UK. Vegetable (rapeseed) oil was purchased from Tesco Ltd, UK. Food grade glycerol (APC Pure) was purchased from APC Ltd, East Tame Business Park, Cheshire SK14 4GX, UK.

[0130] Measurement method Water dispersion test A 0.2 g piece of film was placed in 600 ml of boiling water for 3 minutes with an overhead stirrer at 750 rpm positioned off-center so as not to touch the film. The water was observed for the presence or absence of debris. After this time, the mixture was passed through a 2 mm mesh sieve. The appearance of the residue collected on the sieve, if any, was observed and recorded. The film piece was carefully removed from the mesh using tweezers and the mass was measured.

[0131] Film Tensile Strength and / or % Elongation Test The films were tested according to ASTM D882-18 Tensile Properties of Thin Plastic Sheets using a Tinius Olsen 5ST tensile tester equipped with a 100N load cell.

[0132] The test films were cut into 8.0 cm x 1.0 cm strips. Film thickness was measured at six points (three on each side of the strip being tested) with a micrometer (DML 3701P6 from RDM Test Equipment) and the results were averaged to determine the average cross-sectional thickness. The strips were then conditioned to 76% relative humidity (RH) at 5°C by exposing the film in a humidity chamber at 76% RH / 5°C for at least 24 hours to ensure the strips were equilibrated before testing. Conditions were measured using commonly available devices, such as a Fisherbrand™ Traceable™ thermometer / clock / humidity monitor. Such conditions are typically those of a domestic refrigerator.

[0133] Alternatively, the strips were conditioned to 55% relative humidity at 22° C. using the same method, such conditions being those typically encountered in room temperature packaging and storage facilities.

[0134] To test the films, the strips were removed from the humidity chamber and clamped by parallel clamps on a 5ST test head with a 5 cm gap between the clamps. The upper clamp attached to the load cell was then moved upward at a constant rate of 50 mm / min to stretch the film until breakage and the force applied to the load cell was recorded. To minimize film state changes, this procedure was performed within 1 minute of removing the film sample from the humidity chamber. Tensile strength is the force at break divided by the average cross-sectional area of ​​the film before conditioning and testing. The % break strain is calculated as (film length at break-initial film length) / initial film length) x 100.

[0135] Transparency test A strip of film 0.09 mm ± 0.01 mm thick was placed over the printed letters and the transparency of the film was recorded.

[0136] Example 1 Preparation of films Monolayer films (E1-E3 and E5) and multilayer films (E4, E6-E11) were prepared according to the procedures described below. Five comparative monolayer films (C1-C5) were also prepared according to the procedures described below.

[0137] Preparation of starch-only monolayer film C1 (i) Preparation of the starch mixture 22.50 g of soluble potato starch was dispersed in 150 g of room temperature deionized water by stirring in a 250 ml flask. 5.625 g of glycerol and 0.23 g of vegetable oil were then added and the suspension was stirred. The suspension was then sonicated (high intensity ultrasound) for 14 minutes and 15 seconds using a Bandelin Sonopuls HD4200 equipped with a TS113 probe. The sonicator was set at 95% amplitude with a cycle of 1 second on and 0.2 seconds off. Stirring was performed throughout the sonication to ensure homogenous suspension. After sonication, 0.54 g of lactic acid was added with stirring. There was no further heating, but the energy of the sonication raised the temperature of the mixture to above 80° C. by the end of the sonication period. The mixture was then placed in a heated ultrasonic water bath at 80° C. for 30 minutes to allow trapped air bubbles to escape.

[0138] (ii) Film formation 25 ml of the mixture produced in step (i) was poured into a 50 ml Falcon tube through a tea strainer to remove any remaining large lumps. The mixture was then further degassed by removing large bubbles with a pipette and placing the Falcon tube in an ultrasonic bath at 80° C. for 5 minutes. The mixture was removed, cooled to 55° C., and poured onto a flat glass plate having a Mylar surface. The liquid was spread evenly on the plate using a RK K Control Coater Model 101 equipped with a knife edge to obtain a film of uniform thickness of 1000 microns. The glass plate was then placed in an oven at 80° C. for 1 hour. After this time, the film could be peeled off from the test-prepared Mylar surface.

[0139] Preparation of pea protein isolate (PPI) monolayer film C4 (i) Preparation of PPI mixtures 30 g water was mixed with 7.5 g pea protein isolate in a 250 ml tall beaker using an overhead stirrer to form a homogenous paste. 70 ml acetic acid was then added with stirring along with 1.876 g glycerol. The suspension was then sonicated (high intensity ultrasound) for 7 minutes and 30 seconds using a Bandelin Sonopuls HD4200 equipped with a TS113 probe. The sonicator was set at 50% amplitude with a cycle of 1 second on and 0.2 seconds off. Stirring was intermittent throughout the sonication to ensure the suspension was homogenous.

[0140] (ii) Film formation 25 mL of the mixture produced in step (i) was then cast into a film following the procedure described in step (ii) of the preparation of film C1.

[0141] Preparation of protein-starch monolayer film E1 (i) Preparation of the starch mixture 21.38 g of soluble potato starch was dispersed in 142.5 g of deionized water at room temperature in a 250 ml flask by stirring. 5.625 g of glycerol and 0.23 g of vegetable oil were then added and the suspension was stirred. The suspension was then sonicated (high intensity ultrasound) according to the procedure described in step (i) of the preparation of film C1.

[0142] (ii) Preparation of PPI mixtures 30 g water was mixed with 7.5 g pea protein isolate (PPI) in a 250 ml tall beaker using an overhead stirrer to form a homogenous paste. 70 ml acetic acid was then added with stirring. The mixture was then sonicated and processed according to the procedure described in step (i) of the preparation of film C4.

[0143] (iii) Preparation of Protein-Starch Mixtures 15 ml of the PPI mixture from step (ii) and 0.54 g of lactic acid were added to the total starch mixture produced in step (i). The combined mixture was sonicated for 1 minute at 50% amplitude with a cycle of 1 second on and 0.2 seconds off using a Sonopuls HD4200. The combined mixture was then placed in an ultrasonic bath at 80° C. for 5 minutes to aid in the removal of air bubbles.

[0144] (iv) Film formation 25 mL of the mixture produced in step (iii) was then cast into a film following the procedure described in step (ii) of the preparation of film C1.

[0145] Preparation of protein-starch monolayer film C2 (i) Preparation of the starch mixture The starch mixture was prepared according to the procedure described in step (i) of the preparation of film E1.

[0146] (ii) Preparation of PPI mixtures The PPI mixture was prepared according to the procedure described in step (ii) of the preparation of film E1.

[0147] (iii) Preparation of Protein-Starch Mixtures 7.5 ml of the PPI mixture from step (ii) and 0.54 g of lactic acid were added to the total starch mixture from step (i). The mixture was then sonicated and prepared according to the procedure described in step (iii) of the preparation of film E1.

[0148] (iv) Film formation 25 mL of the mixture produced in step (iii) was then cast into a film following the procedure described in step (ii) of the preparation of film C1.

[0149] Preparation of protein-starch monolayer film C3 (without organic acid treatment step) (i) Preparation of the starch mixture The starch mixture was prepared according to the procedure described in step (i) of the preparation of film E1.

[0150] (ii) Preparation of PPI mixtures Pea protein isolate (PPI), 7.5 g, was added to 100 g water in a 250 ml tall beaker using an overhead stirrer to form a homogenous paste. The PPI mixture was then sonicated according to the procedure described in step (i) of the preparation of film C4.

[0151] (iii) Preparation of Protein-Starch Mixtures 15 ml of the PPI mixture from step (ii) and 0.54 g of lactic acid were added to the starch mixture from step (i). The combined mixture was sonicated for 1 minute at 50% amplitude with a cycle of 1 second on and 0.2 seconds off using a Sonopuls HD4200. The combined mixture was then placed in an ultrasonic bath at 80° C. for 5 minutes to aid in the removal of air bubbles.

[0152] (iv) Film formation 25 mL of the combined mixture produced in step (iii) was then cast into a film following the procedure described in step (ii) of the preparation of film C1.

[0153] Preparation of protein-starch monolayer film E5 (i) Preparation of the starch mixture The starch mixture was prepared according to the procedure of step (i) of the preparation of film C1.

[0154] (ii) Preparation of PPI mixtures The PPI mixture was prepared according to the procedure described in step (i) of the preparation of film C4.

[0155] (iii) Preparation of Protein-Starch Mixtures 150 ml of the PPI mixture from step (ii) and 0.54 g of lactic acid were added to the total starch mixture from step (i) to form a combined mixture. The combined mixture was sonicated for 3 minutes at 50% amplitude with a cycle of 1 second on and 0.2 seconds off using a Bandelin Sonopuls HD4200. The combined mixture was then placed in an ultrasonic bath at 80° C. for 5 minutes to aid in the removal of air bubbles.

[0156] (iv) Film formation 25 mL of the combined mixture from step (iii) was then cast into a film following the procedure described in step (ii) of the preparation of film C1.

[0157] Preparation of protein-starch monolayer film E2 (i) Preparation of the starch mixture A starch mixture was prepared according to the procedure described in step (i) of the preparation of film C1, except that 19.13 g starch and 127.50 g water were used.

[0158] (i) Preparation of PPI mixtures The PPI mixture was prepared according to the procedure described in step (ii) of the preparation of film E1.

[0159] (iii) Preparation of Protein-Starch Mixtures 45 ml of the PPI mixture from step (ii) and 0.54 g of lactic acid were added to the starch mixture from step (i). The combined mixture was sonicated for 3 minutes at 50% amplitude with a cycle of 1 second on and 0.2 seconds off using a Sonoplus 4000. The combined mixture was then placed in an ultrasonic bath at 80° C. for 5 minutes to aid in the removal of air bubbles.

[0160] (iv) Film formation 25 mL of the combined mixture from step (iii) was cast into a film following the procedure described in step (ii) of the preparation of film C1.

[0161] Preparation of protein-starch monolayer film E3 (i) Preparation of the starch mixture A starch mixture was prepared according to the procedure described in step (i) of the preparation of film C1, except that 16.88 g starch and 112.5 g water were used.

[0162] (ii) Preparation of PPI mixtures The PPI mixture was prepared according to the procedure described in step (ii) of the preparation of film E1.

[0163] (iii) Preparation of Protein-Starch Mixtures 75 ml of the PPI mixture from step (ii) and 0.54 g of lactic acid were added to the starch mixture from step (i). The combined mixture was sonicated for 3 minutes at 50% amplitude with a cycle of 1 second on and 0.2 seconds off using a Bandelin Sonopuls HD4200. The combined mixture was then placed in an ultrasonic bath at 80° C. for 5 minutes to aid in the removal of air bubbles.

[0164] (iv) Film formation 25 mL of the combined mixture from step (iii) was then cast into a film following the procedure described in step (ii) of the preparation of film C1.

[0165] Protein-starch multilayer film E4 (i) Preparation of the starch mixture The starch mixture was prepared according to step (i) of the preparation of film E1.

[0166] (ii) Preparation of PPI mixtures The PPI mixture was prepared according to step (ii) of the preparation of film E1.

[0167] (iii) Preparation of Protein-Starch Mixtures A combined PPI and starch mixture was prepared according to step (iii) of the preparation of film E1.

[0168] (iv) Film Formation - First Layer 25 mL of the combined mixture from step (iii) was cast into a film according to step (ii) of the preparation of Film C1, except that a wet film thickness of 900 microns was applied onto the Mylar surface of a glass plate. The film was allowed to dry at 80° C. for 60 minutes.

[0169] (v) Film Formation - Second Layer The film from step (iv) was dried and 1.594 g glycerol and 0.064 g vegetable oil were added to the remaining 85 ml PPI mixture from step (ii). The mixture was sonicated for 2 minutes at 50% amplitude with a cycle of 1 second on and 0.2 seconds off using a Bandelin Sonopuls HD4200. The mixture was then degassed and cooled to 55°C.

[0170] 7 ml of the mixture was then spread onto the exposed surface of the dried glass prepared in step (iv) (i.e., the surface not in contact with the glass plate) using a RK K Control Coater Model 101 equipped with a Tan K-bar with a wire diameter of 1.52 mm to obtain an approximately 120 micron thick wet film of the PPI mixture. The plate was then placed back into the oven at 80° C. for 15 minutes to form the multilayer film E4.

[0171] Preparation of protein-starch monolayer film C5 (without organic acid treatment step) (i) Preparation of the starch mixture 11.25 g of soluble potato starch was dispersed in 75 g of room temperature deionized water by stirring in a 250 ml flask. 5.625 g of glycerol and 0.23 g of vegetable oil were then added and the suspension was stirred. The suspension was then sonicated (high intensity ultrasound) for 7 minutes and 30 seconds using a Bandelin Sonopuls HD4200 with a TS113 probe. The sonicator was set at an amplitude of 95% amplitude with a cycle of 1 second on and 0.2 seconds off. Stirring was performed throughout the sonication to ensure homogenous suspension. There was no further heating, but the energy of the sonication raised the temperature of the mixture to above 80° C. by the end of the sonication period. The mixture was then placed in a heated ultrasonic water bath at 80° C. for 30 minutes to allow trapped air bubbles to escape.

[0172] (ii) Preparation of PPI mixtures Pea protein isolate (PPI), 7.5 g, was added to 100 g water in a 250 ml tall beaker using an overhead stirrer to form a homogenous paste. The PPI mixture was then sonicated according to the procedure described in step (i) of the preparation of film C4.

[0173] (iii) Preparation of Protein-Starch Mixtures 150 ml of the PPI mixture from step (ii) and 0.54 g of lactic acid were added to the starch mixture from step (i). The combined mixture was sonicated for 3 minutes at 50% amplitude with a cycle of 1 second on and 0.2 seconds off using a Bandelin Sonopuls HD4200. The combined mixture was then placed in an ultrasonic bath at 80° C. for 5 minutes to aid in the removal of air bubbles.

[0174] (iv) Film formation 25 mL of the combined mixture from step (iii) was cast into a film following the procedure described in step (ii) of the preparation of film C1.

[0175] Preparation of protein-starch multilayer film E6 (i) Preparation of the starch mixture 75g of soluble potato starch was added to 500g of room temperature deionized water in a Klarstein food processor (Grand Prix Chef Edition). 21.77g of glycerol was then added and the program was started: temperature 85°C, speed 4, 45 minutes. After 45 minutes, the solution was removed from the food processor, poured into a suitable container and degassed using a Synergy FlackTek Speedmixer with the following parameters: 3 minutes, 2000 rpm, 50 mBar.

[0176] (ii) Preparation of PPI mixtures 60g water was mixed with 15g pea protein isolate (PPI) and 3.75g glycerol in a 250ml tall beaker using an overhead stirrer to form a homogenous paste. 140ml acetic acid was then added with stirring. The mixture was then sonicated (high intensity ultrasound) for 15 minutes using a Bandelin Sonopuls HD4200 with a TS113 probe. The sonicator was set at 50% amplitude with 1 second on and 0.2 seconds off cycles. Stirring was intermittent throughout the sonication to ensure homogenous suspension. Once sonicated, the slurry was poured into a suitable container and degassed using a Synergy FlackTek Speedmixer using the following parameters: 2 minutes, 2000 rpm, 999mBar.

[0177] (iii) Film-forming first layer The starch mixture from (i) was poured onto a flat glass plate with a Mylar surface. The liquid was spread evenly onto the plate using a RK K303S Multicoater equipped with a knife edge to obtain a film of uniform thickness of 500 microns. The glass plate was then placed in an oven at 80° C. for 1 hour. After this time, the film could be peeled off from the test-prepared Mylar surface.

[0178] (iv) Film-forming second layer 7 ml of mixture (ii) was then spread onto the exposed surface of the dry film prepared in step (iv) (i.e., the surface not in contact with the glass plate) using a RK K303S Multicoater equipped with a Black K-bar with a wire diameter of 0.51 mm to obtain an approximately 40 micron thick wet film of the PPI mixture. The plate was then placed back into the oven at 80° C. for 15 minutes to form multilayer film E6.

[0179] Preparation of protein-starch multilayer film E7 (i) Preparation of the starch mixture 128.25 g of soluble potato starch was added to 855 g of room temperature deionized water in a Klarstein food processor (Grand Prix Chef Edition). Then 39.1 g of glycerol and 1.36 g of vegetable oil were added and the program was started: temperature 85° C., speed 4, 45 minutes.

[0180] (ii) Preparation of PPI mixtures 30 g water was mixed with 7.5 g pea protein isolate (PPI) in a 250 ml tall beaker using an overhead stirrer to form a homogenous paste. 70 ml acetic acid was then added with stirring. The mixture was then sonicated (high intensity ultrasound) for 7 minutes and 30 seconds using a Bandelin Sonopuls HD4200 equipped with a TS113 probe. The sonicator was set at 50% amplitude with a cycle of 1 second on and 0.2 seconds off. Stirring was intermittent throughout the sonication to ensure the suspension was homogenous.

[0181] (iii) Preparation of Protein-Starch Mixtures 90ml of the PPI mixture from step (ii) and 1.60g lactic acid were added to the total starch mixture produced in step (i). The combined mixture was stirred for a further 5 minutes. After a total of 50 minutes, the combined mixture was removed from the food processor, poured into a suitable container and degassed using a Synergy Flacktek Speedmixer with the following parameters: 3 minutes, 2000 rpm; 50 mBars.

[0182] (iv) Film Formation - First Layer Once the mixture from step (iii) was degassed, it was poured onto a flat glass plate with a Mylar surface. The liquid was spread evenly onto the plate using a RK K303S Multicoater equipped with a knife edge to obtain a film of uniform thickness of 900 microns. The glass plate was then placed in an oven at 80°C for 1 hour.

[0183] (v) Film Formation - Second Layer While the film of step (iv) was dried, 37.5 g of water was mixed with 9.38 g of pea protein isolate (PPI) and 2.72 g of glycerol in a 250 ml tall beaker using an overhead stirrer to form a homogenous paste. 88 ml of acetic acid was then added with stirring. The mixture was then sonicated (high intensity ultrasound) for 9 minutes and 22 seconds using a Bandelin Sonopuls HD4200 equipped with a TS113 probe. The sonicator was set at 50% amplitude with a cycle of 1 second on and 0.2 seconds off. Stirring was intermittent throughout the sonication to ensure the suspension was homogenous.

[0184] 7-15 ml of the mixture was then spread onto the exposed surface of the dry film prepared in step (iv) (i.e., the surface not in contact with the glass plate) using a RK K303S Multicoater equipped with a Brown K-bar with a wire diameter of 1.02 mm to obtain an approximately 80 micron thick wet film of the PPI mixture. The plate was then placed back into the oven at 80°C for 15 minutes to form the multilayer film E7.

[0185] Preparation of starch-protein multilayer film E8 (i) Preparation of the starch mixture 500 ml of deionized water was mixed with 50 g of potato starch in a 600 ml beaker at room temperature using an overhead stirrer. 21.43 g of glycerol was then added and the suspension was stirred. The suspension was then sonicated (high intensity ultrasound) for 50 minutes at 95% amplitude with a cycle of 1 second on, 0.2 seconds off using a Bandelin Sonopuls HD4200 with a TS113 probe. Stirring was performed throughout the sonication to ensure homogenous suspension. The solution was then placed in an ultrasonic bath at 80°C for 30 minutes to remove bubbles.

[0186] (ii) Film formation – starch layer 25 ml of the mixture produced in step (i) was poured into a 50 ml Falcon tube. The mixture was then further degassed by removing large bubbles with a pipette and placing the Falcon tube in an ultrasonic bath at 80° C. for 5 minutes, after which the mixture was removed and cooled to 55° C. The liquid was poured onto a flat glass plate with a Mylar surface and spread evenly on the plate using a knife blade to obtain a wet film thickness of 500 microns. The glass plate was then placed in an oven at 80° C. for 60 minutes to form a dry film layer.

[0187] (iii) Preparation of protein mixtures 150g water was mixed with 37.5g pea protein isolate (PPI) in a 600ml beaker at room temperature using an overhead stirrer to form a homogenous paste. 350ml acetic acid and 10.89g glycerol were then added with stirring. The mixture was then sonicated (high intensity ultrasound) for 37 minutes and 30 seconds using a Bandelin Sonopuls HD4200 equipped with a TS113 probe. The sonicator was set at 50% amplitude with a cycle of 1 second on and 0.2 seconds off. Stirring was intermittent throughout the sonication to ensure the suspension was homogenous.

[0188] (iv) Film formation – protein layer 25 ml of the mixture produced in step (iii) was poured into a 50 ml Falcon tube. The mixture was then further degassed by removing large bubbles with a pipette and placing the Falcon tube in an ultrasonic bath at 80° C. for 1 minute, followed by cooling to 55° C., and then spread using a knife blade onto the exposed surface of the dry film prepared in step (ii) (i.e., the surface not in contact with the glass plate) to obtain an approximately 500 micron thick wet film of the PPI mixture. The plate was then placed in an oven at 80° C. for 30 minutes to form a multilayer film.

[0189] Preparation of starch-protein multilayer film E9 (i) Preparation of the starch mixture 500 ml of deionized water was mixed with 50 g of potato starch in a 600 ml beaker at room temperature using an overhead stirrer. 21.43 g of glycerol was then added and the suspension was stirred. The suspension was then sonicated (high intensity ultrasound) for 50 minutes using a Bandelin Sonopuls HD4200 with a TS113 probe. The sonicator was set at 95% amplitude with a cycle of 1 second on and 0.2 seconds off. Stirring was performed throughout the sonication to ensure homogenous suspension. There was no further heating, but the energy of the ultrasound raised the temperature of the mixture to above 80° C. by the end of the sonication period. The mixture was then placed in a heated ultrasonic water bath at 80° C. for 30 minutes to allow trapped air bubbles to escape.

[0190] (ii) Film formation – starch layer 15 mL of the mixture from step (i) was poured into a 50 ml Falcon tube. The mixture was then further degassed by removing large bubbles with a pipette and placing the Falcon tube in an ultrasonic bath at 80° C. for 5 minutes before being removed and cooled to 55° C. The liquid was poured onto a flat glass plate with a Mylar surface and spread evenly on the plate using a RK K Control Coater Model 101 equipped with a knife blade to obtain a wet film thickness of 300 microns. The film was left to dry at 80° C. for 30 minutes.

[0191] (iii) Preparation of protein mixtures 150 ml of deionized water was mixed with 37.5 g of pea protein isolate (PPI) in a 600 ml beaker at room temperature using an overhead stirrer to form a homogenous paste. 350 ml of acetic acid and 10.89 g of glycerol were then added with stirring. The mixture was then sonicated (high intensity ultrasound) for 37 minutes and 30 seconds using a Bandelin Sonopuls HD4200 equipped with a TS113 probe. The sonicator was set at 50% amplitude with a cycle of 1 second on and 0.2 seconds off. Stirring was intermittent throughout the sonication to ensure the suspension was homogenous.

[0192] (iv) Film formation – protein layer 25 ml of the mixture from step (iii) was poured into a 50 ml Falcon tube. The mixture was then further degassed by removing any large bubbles with a pipette and placing the Falcon tube in an ultrasonic bath at 80° C. for 1 minute, followed by cooling to 55° C., and then spread using a RK K Control Coater Model 101 equipped with a knife blade onto the exposed surface of the dry film prepared in step (ii) (i.e., the surface not in contact with the glass plate) to obtain an approximately 500 micron thick wet film of the PPI mixture. The plate was then placed in an oven at 80° C. for 30 minutes to form a multilayer film.

[0193] Preparation of starch-protein multilayer film E10 (i) Preparation of the starch mixture 2000 ml of room temperature deionized water was mixed with 85.7 g of glycerol in a Klarstein food processor (Grand Prix Chef Edition). 200 g of potato starch was then added and the program: temperature 85°C, speed 4, 45 minutes was started. The batch was then transferred to a VEVOR vacuum chamber connected to a 1 / 4 hp 3 cfm single stage vacuum pump for degassing. The material was poured into a container which was then sealed and the vacuum pump was operated for 5-10 minutes until the slurry was free of air bubbles.

[0194] (ii) Film formation – starch layer The casting of the starch layer was carried out using a standard roll-to-roll machine with a pressure vessel, a fluid pump, a slot die unit, a feed roller, a web across a series of rollers and load cells allowing tension control, a drying oven approximately 2 meters long, and a take-up roller. The backing material used for this casting was a standard 72 μm PET roll. The starch mixture prepared in (i) was poured into the pressure vessel and then tightly closed to ensure no leakage. The vessel was then pressurized to 1-2 bar and the starch mixture was pumped by a progressive cavity pump to feed the slot die. The equipment was set to the following parameters: Oven temperature: 100~140℃ Line speed: 0.4~1m / min Slot die width: 300mm Fluid pump flow rate: 50~120ml / min Slot die distance from backing material: 0.2~0.4mm Shim distance between slot lips: 150~200μm

[0195] The wet thickness varied between 300-550 μm and was adjusted to approximately 350 μm by adjusting the parameters. The film emerging from the oven drying and the resulting roll was then removed from the collection winder and positioned as a feed roll so that a second film could be cast on top of it.

[0196] (iii) Preparation of protein mixtures 740g water was mixed with 94.4g pea protein isolate (PPI) in a 1000ml tall beaker using an overhead stirrer to form a homogenous slurry. 60g acetic acid and 23.6g glycerol were then added with stirring. The mixture was placed in a 90°C water bath for 20-30 minutes with shaking every 10 minutes. After this step, the slurry was transferred to a Hielscher 1kW sonicator (with booster) and a total of 200kJ of energy was applied with shaking approximately every 30 minutes. The sonication took approximately 30 minutes to reach the target energy. The process was repeated three times to produce a total of 2400ml of product, which was then degassed using a Synergy Flacktek Speedmixer for 3-5 minutes at settings of 2000rpm; 50mBar.

[0197] (iv) Film formation – protein layer The coating equipment as described in step (ii) was used for this layer, except that the backing had already been coated with a first layer of starch. The protein mixture prepared in step (iii) was poured into a pressure vessel and the coater was set to the following parameters: Oven temperature: 100~130℃ Line speed: 0.7~1m / min Slot die width: 300mm Fluid pump flow rate: 40~120ml / min Slot die distance from backing material: 0.2~0.25mm Shim distance between slot lips: 150~200μm

[0198] The multilayer film emerged from the oven drying exhibiting minimal bubbles and / or defects. The two layers each had a thickness of approximately 30 μm.

[0199] Preparation of starch-protein multilayer film E11 (i) Preparation of the starch mixture The starch mixture was prepared according to the procedure described in step (i) of the preparation of film E10.

[0200] (ii) Film formation – starch layer 2000 ml of the batch described in step (i) was cast into a roll of film following the procedure described in step (ii) of the preparation of film E10.

[0201] (iii) Preparation of protein mixtures 1200 g of deionized water was measured and poured into a large 3 L stainless steel vessel. The vessel was placed in a water bath set at 95° C. and the water was mixed at 900 rpm using an overhead stirrer equipped with an impeller blade. 320 g of pea protein isolate was added to the mixture and left to stir for 3 minutes until a homogenous mixture was formed. 800 g of acetic acid was measured and poured into the mixture which was stirred at 700 rpm for 40 minutes. The temperature of the mixture was measured to ensure it had reached 85° C. and, if necessary, stirring was continued for at least 10 minutes to ensure the mixture had reached 85° C. The mixture was then sheared using a Silverson high shear homogenizer at 7000 rpm for 3 minutes.

[0202] The freshly shear mixed slurry was then poured into a plastic flat container or large Petri dish to a height of approximately 10 mm. The container was then sealed and stored in a refrigerator for 16-28 hours.

[0203] After storage, the formed gel was cut into 1 cm x 1 cm squares and the gel cubes were transferred to a 75 μm filter bag using a spatula. The bag with the gel cubes was then suspended in a bucket containing 6 liters of reverse osmosis water. After 1 hour and 30 minutes, 3 liters of water were removed and replaced with 3 liters of fresh reverse osmosis water. The bag and gel cubes were left in the water and swirled every 20 minutes for 90-150 minutes. The pH was measured and if it was below 2.9, then the previous two steps were repeated until the pH reached a value above 2.9.

[0204] The filter bag was then removed from the water and squeezed vigorously to remove as much excess water as possible. The slurry was then transferred to a 1 liter container and the gel mash was sheared using an Ultra-Turrax mixer at 15000 rpm for 15 minutes with shaking every 5 minutes. 21.71 g of glycerol was then added to the mixture followed by an additional 5 minutes of Ultra-Turrax mixing at 15000 rpm. The container was then placed in an ice bath and the mixture was sonicated with a Hielschler sonicator until it reached 0.25 kJ / ml. The slurry was filtered through a 212 μm mesh and stored in a plastic bucket.

[0205] (iv) Film formation – protein layer 2000 ml of the mixture prepared in step (iii) was poured into the pressurized vessel of the coater described in step (iv) of film E10. The following parameters were used in the equipment settings: Oven temperature: 100~115℃ Line speed: 0.5~0.9m / min Slot die width: 300mm Fluid pump flow rate: 50~90ml / min Slot die distance from backing material: 0.15~0.2mm Shim distance between slot lips: 150~200μm

[0206] The multilayer film emerged from the oven drying exhibiting minimal bubbles and / or defects. The two layers each had a thickness of approximately 30 μm.

[0207] The composition of each of the films prepared is shown in Table 1.

[0208] [Table 1A]

[0209] [Table 1B]

[0210] [Table 1C]

[0211] [Table 1D]

[0212] Example 2 Film characteristics The films prepared in Example 1 were then tested to determine their physical properties. The test methods used to determine dispersion properties, tensile strength, % breaking strain and clarity are detailed above in the Measurement Methods section and the results are shown in Tables 2a, 2b, 3 and 4 (Table 2, Table 3, Table 4 and Table 5) or in Figure 2 for clarity testing.

[0213] [Table 2]

[0214] The results in Table 2a show that the film containing no vegetable protein (C1) has a very low tensile strength combined with a very high % breaking strain, making it very difficult to handle and process into a desired form, for example, under industrial conditions. The film containing almost no starch (C4) has good tensile strength but a much reduced % breaking strain, indicating that the film is brittle. Again, this makes the film more difficult to process, for example, under industrial conditions.

[0215] The data also demonstrates that the addition of vegetable protein (PPI) to starch (as in E1, E2, E3, E5) increases the film tensile strength to an optimal level and decreases the % breaking strain to an optimal level, such that the film can be used to coat or encapsulate products.

[0216] The data also demonstrate that films prepared as multilayers (E4) have increased tensile strength relative to films with the same starch:protein mass ratio prepared as a monolayer (E3).

[0217] The data also demonstrate that films prepared as multiple layers with higher starch to plant protein (PPI) ratios (E6 and E7) have sufficient tensile strength and % strain at break.

[0218] The data also demonstrate that films prepared as multilayers with lower ratios of starch to plant protein (PPI) (E8 and E9) have good tensile strength and % strain at break.

[0219] [Table 3]

[0220] The results in Table 2b demonstrate that films with lower starch:protein ratios and lower levels of acetic acid, such as E10 and E11, still have good tensile strength and elongation at 22° C. and 55% RH when compared to similar films E8 and E9 with higher acetic acid.

[0221] [Table 4]

[0222] Table 3 shows the effect of organic acid pretreatment of protein. For low levels of protein compared to starch, as in films E1 and C3, the % breaking strain is higher with organic acid pretreatment of protein at both cold and room temperature, while the tensile strength is unchanged. This results in a film that is less brittle and easier to process as a packaging material.

[0223] The data also demonstrate that as the protein level in the film increases, it becomes increasingly difficult to prepare a transparent film that does not crack when dried, as seen in the case of C5, which did not produce a viable film that could be tested. However, film E5, of the same composition but made from organic acid treated protein, is a transparent film with good tensile strength and % strain at break, resulting in a robust and easily handled film.

[0224] [Table 5]

[0225] The comparative film containing no vegetable protein (C1) is highly soluble. The comparative film containing primarily vegetable protein (C4) is not soluble, does not disperse, and leaves a residue of 0.44 g. The presence of low levels of protein in the monolayer films (E1, E2, E3, E4) results in films that are either water soluble or water dispersible, leaving a residue of 0.15 g or less on the sieve in the dispersion test.

[0226] A comparison of the data for films E3 and E4 demonstrates that the dispersion is equally good whether the film is a homogeneous monolayer film or a multilayer film.

[0227] The multilayer films with higher starch to vegetable protein ratios (E6 and E7) also demonstrate good dissolution or dispersibility, with less than 0.22 g residue, lower than the protein-only comparative film C4. The dispersion test residue for E6 is particularly low due to the lower total film thickness compared to E7.

[0228] Figure 2 is a photograph of a portion of the film of Example 1 overlaid with printed text, showing the transparency of the film. The image shows that the film without vegetable protein (C1) is highly transparent. As the protein level in the film increases (E1, E2, E4, E5), the film still has good transparency, which is a useful feature for packaging materials.

[0229] Example 3 Using films to coat / encapsulate products Protocols for coating / encapsulating dishwasher tablets and soup stock cubes A 90x60mm piece of Film E4 was cut out with a sharp knife. The two long edges were folded over with the starch layer on the inside and then the edges were sealed together using an RS PRO Heat Sealer (300mm) on setting 2. A dishwasher or soup stock block tablet was then placed inside the semi-formed flow wrap. The tablet was then centred and both ends of the film were sealed. Excess material was cut off. Figure 3a shows a soup stock block enclosed in a sealed sachet of Film E4 whilst Figure 3c shows a dishwasher tablet enclosed in a sealed sachet of Film E4.

[0230] Protocol for preparation of soap tablets: A 150x80mm piece of Film E4 was cut out with a sharp knife. The two long edges were folded over with the starch layer on the inside and the edges were sealed together using an RS PRO Heat Sealer (300mm) on setting 2. The soap bar was placed inside the semi-formed flow wrap. A tablet was then placed in the centre and both ends of the film were sealed. Excess material was cut off. Figure 3b shows the soap bar enclosed in a sealed sachet of Film E4.

[0231] The results show that the films of the present invention can effectively coat / encapsulate a variety of products and therefore, they have useful applications as packaging materials.

Claims

1. A film, preferably an edible film, comprising a combination of vegetable protein and starch at 50 wt% or more of the total weight of the film at 55% relative humidity and 22°C, wherein the mass ratio of starch to vegetable protein is in the range of 0.5:1 to 30:1, and the vegetable protein has been pretreated with an organic acid.

2. a first layer comprising starch; a second layer comprising a vegetable protein, the vegetable protein being pretreated with an organic acid; and Including, The film of claim 1 , wherein the second layer is in contact with the first surface of the first layer.

3. 3. The film of claim 2, wherein the first layer further comprises a vegetable protein, the vegetable protein being pretreated with an organic acid.

4. 4. The film of claim 2 or claim 3, wherein the second layer further comprises starch.

5. 3. A film according to claim 1 or 2, wherein the weight ratio of starch to vegetable protein is in the range of from 2:1 to 27.5:1, more preferably from 3.5:1 to 25:1, even more preferably from 7:1 to 25:

1.

6. 3. A film according to claim 1 or 2, wherein the weight ratio of starch to vegetable protein is in the range of 1:2 to 3:1, more preferably 1:1 to 2:

1.

7. 3. The film according to claim 1 or 2, wherein the vegetable protein is selected from soy protein, pea protein, rice protein, potato protein, rapeseed protein, sunflower protein, preferably selected from pea protein, potato protein, rapeseed protein, sunflower protein and / or rice protein, preferably the vegetable protein is pea protein.

8. 3. The film according to claim 1, comprising 2.0 to 40 wt. % of vegetable protein, based on the total mass of the film, at 55% relative humidity and 22°C.

9. 3. The film according to claim 1 or 2, wherein 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, soybean starch, modified starches, or mixtures thereof, preferably the starch is potato starch.

10. 3. The film according to claim 1, comprising 30 to 70 wt. % of starch, based on the total mass of the film, at 55% relative humidity and 22°C.

11. 3. The film according to claim 1, comprising 8 to 20 wt. % water, based on the total weight of the film, at 55% relative humidity and 22°C.

12. 3. The film according to claim 1 or 2, further comprising a plasticizer, preferably the plasticizer is selected from glycerol, polyethylene glycol, propylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, fatty acids, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids and organic acids, or mixtures thereof, more preferably the plasticizer is glycerol.

13. 13. The film of claim 12, comprising 5 to 30 wt. % of plasticizer, based on the total weight of the film, at 55% relative humidity and 22°C.

14. 3. The film according to claim 1 or 2, further comprising a pigment or dye, preferably the pigment or dye is a food colorant, preferably a food colorant derived from a plant source, more preferably a food colorant selected from carotenoids, chlorophyllins, anthocyanins and betanins.

15. 3. The film of claim 1 or 2, further comprising a structural enhancing agent, preferably selected from microcrystalline cellulose, microfibrillated cellulose comprising cellulose fibers extracted from citrus fruit pulp, cellulosic materials comprising fine fibrous cellulose from fermentation, starch microcrystals, clay, or mixtures thereof, preferably microfibrillated cellulose from citrus pulp.

16. 16. The film of claim 15, comprising 0.5 to 5 wt % of the structural enhancing agent, based on the total weight of the film, at 55% relative humidity and 22°C.

17. 3. The film of claim 1 or 2, further comprising a hydrophobic agent, preferably the hydrophobic agent being a plant-based oil or a plant-based fatty acid.

18. 18. The film of claim 17, comprising 0.3 to 2.5 wt % of a hydrophobic agent, based on the total weight of the film, at 55% relative humidity and 22°C.

19. 3. The film according to claim 1, wherein the organic acid used for the pretreatment is selected from acetic acid, alpha-hydroxy acids, and beta-hydroxy acids.

20. 4. The film of claim 2 or 3, wherein the plant protein in the second layer has a protein secondary structure having at least 40% intermolecular β-sheet, at least 50% intermolecular β-sheet, at least 60% intermolecular β-sheet, at least 70% intermolecular β-sheet, at least 80% intermolecular β-sheet, or at least 90% intermolecular β-sheet.

21. 10. A method for preparing the film of claim 1, comprising: (i) mixing starch in water, optionally using sonication, to form a starch mixture; (ii) dissolving the plant protein in water and an organic acid, optionally using sonication, to form a protein solution; (iii) mixing the starch mixture and the protein solution to form a film-forming composition; (iv) forming the film-forming composition into a film; A method comprising:

22. 10. A method for preparing the film of claim 2, comprising: (i) mixing starch in water, optionally using sonication, to form a starch mixture; (ii) forming the starch mixture into a first layer on a surface; (iii) dissolving the plant protein in water and an organic acid, optionally using sonication, to form a protein solution; (iv) forming the protein solution into a second layer on the first surface of the first layer; A method comprising:

23. 3. A product, preferably a food product, coated or encapsulated with a film according to claim 1 or 2.

24. 24. The product of claim 23, which is a soup block.

25. 24. The product of claim 23, which is a powdered food product.

26. 1. A method for coating or encapsulating a product, preferably a food product, comprising the steps of: (i) packaging a product in a film according to claim 1 or 2; (ii) sealing a film around the product; A method comprising:

27. 3. Use of a film according to claim 1 or 2 for coating or encapsulating a product, preferably a food product.

28. 10. A method for releasing a product coated or encapsulated with a film according to claim 1 or 2, comprising: (i) placing the coated or encapsulated product in water; (ii) dispersing the film, thereby releasing the product; A method comprising:

29. 29. The method of claim 28, wherein the product is released during a cooking process or a cleaning process.

30. 1. A film-forming composition, preferably an edible film-forming composition, wherein the mass ratio of starch to vegetable protein is in the range of 0.5:1 to 30:1, and the vegetable protein has been pretreated with an organic acid.

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