WO2007141557A1 - Marking composition and method - Google Patents

Abstract

An edible ink composition suitable for marking substrates, particularly foodstuffs (especially meat) under conditions of dampness, high water activity, and/or high humidity, comprises pigment particles in a vehicle which is a solution of a sugar in a solvent containing water and, preferably, alcohol. It preferably also contains a gelling agent, preferably carragheenan. The pigment may be the residue left after extraction of soluble components from a food material (e.g. coffee beans).

Description

MARKING COMPOSITION AND METHOD

FIELD OF INVENTION

The present invention relates to the production of inks suitable for direct or indirect application to edible foodstuffs which may have wet surfaces and/or high water activity and/or a natural high water content including red or white meat carcasses, meat primals and cuts, meat pieces and meat products, fish, fish meat and products, fruits and vegetables for the purpose of adding data, information, logos and other required markings directly to the food surfaces.

It also relates to the methods needed to successfully apply said inks, to protecting the integrity of the applied ink/mark and the apparatus needed to provide a successful application particularly direct application by ink jet printers.

DESCRIPTION OF THE BACKGROUND AND STATE OF THE ART

The direct marking of foodstuffs is not new. Pictures and images have been directly applied to cakes and biscuits using food colorings derived from plant extracts and food edible dyes. Markings, logos and data have been directly applied to egg shells using ink jet printers for several decades .

Identification markings have been manually or machine applied to meat carcasses using sprays or stampings. Such methods have also been used to add regulatory approvals and meat plant identifications: a classic example being the marking of Danish bacon backs and bellies with a distinct line pattern and alphanumeric printing so that when the backs were sliced, each slice retained some element of the applied pattern and printing. Newman (US 6148249) describes a method of tracking and tracing animals, meat carcasses, meat primals and meat products using information carried alphanumerically, as data in colour coded or 2D Matrix formats directly applied onto foodstuffs .

An inkless method for fruit using a high energy laser that caused a change of colour only where the laser beam made contact with the fruit surface is described in

US5,660,747. However, such techniques are impractical for meat. On meat protein the flexible surfaces do not allow the formation of distinctive elements arid subsequent ^Λbleeding' of pigments and proteins further obscure any such marks. The problem with fat surfaces is even more impractical as the laser merely causes the fat to melt and then resolidify without leaving any discernible mark. One exception to this is with smoked foods. US Patent Application 20050276887 describes a technique where the laser energy reacts only with the smoked surface of the foodstuff so as to generate a different colour at the point of contact with the laser. It should also be remembered that most smoking methods will cause a change of state and/or denaturation at the surface making the immediate surface more resilient. This can be seen easily in the char marking technique of Naivar (US5, 992, 305) where hot metal rods are applied directly to the surfaces of the meat so that denaturation occurs on contact and this itself generates a colour change.

A method for leaving a defined mark or indentation is the drug embossing technique of Gustaesson (US Patent Application 20020009523) . Here, the finished individual tablets or capsules are restrained within their- final packaging and a foil with a raised pattern is applied to the packaging so that with application of pressure the mark on the foil is indented on the product surface. Unfortunately, meat and similar foodstuffs do not possess the required degree of permanent rigidity for such a technique to work. A similar approach is adopted in US Patent Application 20050226975. This uses a mechanical stamp in the form of a print head or a laser to generate the appropriate indentation and then the use of a sprayed food colourant to enhance the differentiation. However the elasticity of meat makes such an approach impractical.

A unique technique using fluorescent dyes is described in US 4,133,294. Here, molluscs are allowed to feed on foodstuffs that have been impregnated with fluorescent dyes sufficient to induce a unique colour change that is more pronounced under specific wavelength illumination. It is used to indicate such actions as movement patterns of the livestock or illegal fishing. However, it is impractical for meat uses and for applications that require the addition of specific logo, data or information.

A technique that uses a combination of dye application and denaturation is described in US 3,961,082. The dye is applied to the collagen casing immediately after its formation and then a physical change is induced in the collagen through either heating or the application of a chemical cross-linking agent. This renders the ink water resistant. Unfortunately, while such an approach is possible with a further processed, heated products, any steps that will lead to any change or denaturation of the native proteins cannot be used with raw products such as meat protein foodstuffs or fruit to render inks permanent.

With the increasing use of ink jet printers, there have been significant recent developments in so-called Hot Melt Inks. These are inks that are effectively solid at lower temperatures for storage but liquid at higher temperatures for ease of application. Descriptions of the form, function and composition of such edible inks are detailed in US Patent Application 20050158434. In this patent application these edible dye-based inks are used principally to mark foods such as cheese, eggs, fruits and confectionery. However it should be noted that all of these foodstuffs types have relatively low water contents, possess low water activity and have exterior surfaces that are essentially lipophilic and/or hydrophobic and therefore present surfaces highly suitable for dye-based inks that contain high wax and resin contents. The surfaces of animal proteins (and many other foods such as vegetables) have high water activities, high water contents, the surfaces are highly hydrophilic and the manufacturing and production environments have high humidities. As a consequence, there are major problems associated with ink adhesion and the bleeding of dye-based inks after application because of water diffusion, water absorption and high humidities.

SUMMARY OF THE INVENTION

This invention relates to methods of preparing pigment- based inks suitable for direct or indirect use on wet surfaces of both edible and non-edible materials, especially foodstuffs with high water activity, high moisture content or prepared in a high humidity- environment, and methods for their direct application. A relative humidity greater than 80%, preferably greater than 90%, may be regarded as high humidity. These inks provide the means and mechanisms for applying data, information, logos, in coded and non-coded formats directly to the surfaces of such foodstuffs especially for the purposes of product recognition, tracking and tracing. These inks can be modified for use on a variety of food and non-food surfaces; they can also be formulated so as to remain essentially liquid and evenly dispersed in solution prior to application and provide integrally protective surfaces once applied making them ideal for use with ink jet printers. It particularly relates to the production of edible pigment-based inks suitable for direct or indirect application to edible and non-edible materials especially adhering to foodstuffs which may have wet surfaces and/or high water activity and/or a natural high water content for the purpose of adding data, information, logos, pricing, advertising and other required markings directly to the food surfaces. Examples of such products include red or white meat carcasses, meat primals and cuts, meat pieces and meat products, fish meat and products, fruits and vegetables.

It further relates to producing such inks using materials and components that are considered safe for use on foods and for human and animal consumption.

It also relates to the specific methods needed to successfully apply said inks, to protect such inks after application and the apparatus needed to provide a successful application.

In a first aspect the invention provides an edible ink composition comprising a) a particulate pigment which is insoluble in water; and b) a vehicle comprising a solution of a food-permitted sugar in a food-permitted solvent comprising water. • Desirably the solvent is substantially non-aqueous, with sufficient water being present to keep the sugar in solution. It may be principally ethanol.

In a second aspect the invention provides a method of producing an edible ink composition comprising mixing together (a) a particulate pigment which is insoluble in water; and b) a vehicle comprising a solution of a food- permitted sugar in a food-permitted solvent comprising water.

In a third aspect the invention provides a method of marking a substrate comprising a step of applying to a surface portion of the substrate an edible ink composition comprising (a) a particulate pigment which is insoluble in water; and (b) a vehicle comprising a solution of a food-permitted sugar in a food-permitted solvent comprising water.

A number of constraints severely limit the type of compounds that can be used in the production of suitable edible inks. Firstly, legislation and regulation in individual countries limit the compounds that can be in direct contact with edible foodstuffs. While such compounds are usually assessed and approved on an individual basis, virtually all such compounds are classified under the GRAS (or equivalent) regulations, i.e. Generally Regarded As Safe.

Secondly, regulations also limit the maximum concentration of such permitted compounds. This has the effect of still further reducing the number of allowable compounds. For example, while a mark applied to foodstuffs may be substantially less than the total residual amount allowed, it is concentrated in a very small area so that a single portion of the product may contain all the marker compound applied and thus exceed the allowable concentrations.

Thirdly, while compounds can be approved for use in and on foods, meat based materials and products as well as meat-based foods are often subjected to still further restriction and curtailment and this may further limit the list of allowable compounds. For example, in the EU, despite the fact there are in excess of 20 allowable food lakes and dyes, only 3 dyes, E129 Allura Red AC, E155

Brown HT, and E133 Brilliant Blue FCF (or combination of one or more of the above) are approved to mark such food products. The problem with these compounds is that they are all water-soluble dyes and will rapidly absorb water from surrounding tissues or the environment and ^Λbleed' into adjacent areas so that the detail of any applied mark is rapidly lost. They also poorly adhere to wet surfaces and consequently often fail to generate a mark with any discernible detail on the food surface.

Fourthly, such dye based inks dry poorly and/or slowly on wet surfaces, especially in production areas with high humidities, so that any mark that is generated is easily damaged without adequate protection.

This patent provides ink formulations and methodologies that provide the necessary protective form and function.

Finally, in a continuous production operation, there is usually only one opportunity per manufacturing tasks to successfully apply the mark and verify it. Therefore the applied mark has to have the required resilience and longevity. This patent application provides practical and working solutions to all of these problems.

DETAILED DESCRIPTIONS OP PRODUCTION, PROPERTIES AND COMPOSITION OF INKS SUITABLE FOR APPLICATION TO WET SURFACES

It will be understood by anyone skilled in the art that although the primary application of these inks is to surfaces of carcasses, meat cuts and products derived from red, white and fish meat, fruits, nuts, seeds and vegetables, they can be applied to any wet surface of both edible and inedible materials. Similarly, we have demonstrated that the ingredients comprising the composition of the inks can be interchanged or substituted with others of similar or suitable properties so as to better suit individual operational conditions and requirements. For example, the amount of adhesion needed for a mark to adhere to a meat cut is quite different to that needed to be applied to a fruit or vegetable.

We have successfully tested the principles described in this patent using food grade Carbon Black mixed with other food grade components to provide all the required properties of a pigment based ink as detailed above. For many years, carbon black was used as a food colouring in foods as diverse as confectionery and cakes. However, Carbon Black has been increasingly linked in clinical and pathology studies as a carcinogen and is now banned from direct application to foodstuffs both in the EU and the USA. Accordingly, we have developed inks that possess similar properties but using components in pigment-based inks that are generally unrestricted in their food use. The major advantage of a pigment-based ink over a dye or lake-based ink is that each droplet is composed of individual or combinations of individual pigmented particles. Not only are the discrete particles able to retain shape and location once applied, the natural pigmentation does not ^Λbleed' when applied to wet surfaces, the particles do not dissolve when exposed to water or other predominantly aqueous-based liquids such as meat proteins which can exude on to cut surfaces.

We have therefore developed a number of different groups of pigment-based inks to suit a wide variety of wet surface applications. As all the ingredients used are taken from the FDA list of GRAS (or equivalent) approved components, all these inks are immediately suitable for food use, especially based applications. We will now detail examples and properties of such inks. However these are merely examples and use of any suitable compounds from GRAS (or equivalent) lists can be substituted.

a) Naturally occurring insoluble or virtually insoluble compounds .

This is the simplest group of materials to utilise as it makes use of two primary but naturally occurring properties, namely a naturally occurring pigmentation and insolubility or very low solubility in water based solvents. As previously stated, all these materials are derived from compounds allowed for food use. Examples of this type, either singly or in combination include, but are not limited, to ferric oxide, ferrous carbonate, iron salts in general, copper carbonate, copper oxide, copper hydroxide, cobalt carbonate, cobalt oxide, iodine, calcium oxide, calcium carbonate, calcium sulphate, magnesium oxide, magnesium silicate, pigmented (i.e non- white) manganese salts, nickel, sodium bicarbonate, stannous chloride, titanium dioxide, zinc carbonate, zinc oxide, talc and hemoglobin. It also extends to compounds that possess the required properties but are currently excluded from food use but may become approved at some later date. This group may also include some organic compounds that are edible and naturally pigmented of which chlorophyll, anthocyanins and porphyrins are examples .

The properties of the inks that include one or more of compounds of this type will vary substantially depending on use. For example, when applied to the skin of a carcass such as. a pig, the skin is naturally hydrophobic and therefore it is a relative simple task to remove water droplets from the application site. Thus the applied ink can be derived of particles suspended in a solvent mixture that ensures that the individual pigmented particles remain discrete and evenly distributed but adhere and remain adhered to the applied surface without deterioration.

While all compounds of this type are usable and functional, preferred compounds are those that produce soft pigment particles such as talc, magnesium oxide, calcium carbonate and calcium sulphate.

b) Naturally occurring insoluble or virtually insoluble materials possessing natural pigmentation but derived from organic sources.

All types of food, raw, cooked, processed and semi- processed are frequently eaten with added materials from organic origins. These can be as diverse as herbs, spices, fruits, vegetables, seeds, etc. This may be in direct contact with the food such as an herb and/or spice mixture, additional to the food or formulation or may be in indirect contact such as a stuffing, sauce or vegetable addition. Many of these foods contain a variety of natural pigments. While the majority are green pigments based on chlorophyll and similar compounds, a significant number possess natural pigments that are not green. These include but are not limited to naturally coloured spices such as saffron, turmeric, paprika, ground mustard seed, ground pepper corns, chili pepper skins and seeds, vanilla pods, cinnamon, nutmeg, pimento, cardamom seeds and jalapeno peppers.

Examples of other coloured additive compounds that can be used as sources of suitable pigments in inks include coffee beans and grounds, cocoa beans and pods, carrots, beetroot, nut shells, seed pods, seeds and skins from fruits and vegetables such as peppers, mangoes, pineapple, plums, dates, grapes, tomatoes, and edible red and brown seaweed.

To make the pigments from these organic materials suitable, a number of steps need to incorporated using allowable solvents and processes that ensure the foodstuffs do not become adulterated and, as such, do not need to be re-approved for food use in their modified form. 1. Extracting all water-soluble components through hot and/or cold extraction methods including boiling. Further solvent extraction may be carried out, e.g. to remove alcohol (ethanol) soluble materials by extraction with ethanol.

2. Freeze drying (or equivalent method) to remove all free and bound water from the raw material so that non-aqueous pigmented components bind themselves to lipid and/or protein-based cellular materials. 3. Grinding using both an aqueous medium to remove any residual water soluble pigments and/or a suitable food approved solvent such as ethanol. 4. Secondary drying to leave the resultant material in a stable condition for storage and/or suspending the ground, pigmented material in a suitable medium such that it can be used in any suitable printer including ink jet, electrostatic or laser, preferentially ink jet for non-contact printing.

c) Pigmented compounds developed from combining food approved dyes and/or lakes and/or naturally occurring pigments to organic and/or inorganic insoluble or virtually insoluble compounds which may or may not possess natural pigmentation As previously outlined, there are very few pigments that are approved for food use. Those that are available are unsuitable for meat-based applications. A typical example is Titanium Dioxide. While this is both an insoluble pigment and food use approved, it is white and as such cannot be satisfactorily used against the majority of meat or carcass surfaces as these are also pale or white in colour. Almost all food approved dyes or lakes are water-soluble and are unsuitable for use on wet surfaces or surfaces with high water activity or water content as they adhere poorly, dry slowly and are subject to 'bleeding' .

However, we have shown that it is possible to produce a suitable insoluble pigment through a number of different methods while working within the constraints imposed by regulations on components allowed to contact food surfaces. The particular methods described here also have the advantage that not only can pigments be made to very specific or precise colours and thus highly specific to individual foods, they can also be manufactured to provide very specific ink properties to optimize their use on very specific wet surfaces or under very specific physical conditions. In summary: 1. One or more sources of food approved soluble pigmentation from any of the groupings previously described is chemically bound to the surface of a suitable insoluble material or combination of suitable insoluble materials, again using any suitable food approved material from the groupings previously described, using chemical methods which would not lead to the adulteration of the resultant combined material on completion of the chemical methodologies.

2. One or more sources of food approved soluble pigmentation from any of the groupings previously described is physically bound to the surface of a suitable insoluble material or combination of suitable insoluble materials, again using any suitable food approved material from the groupings previously described, using physical methods which would ^"not lead to the adulteration of the resultant combined material on completion of the physical methodologies.

3. The production of a suitable pigment using a combination of methods derived from cl and c2.

A further range of compounds can be added to these groupings as they also provide suitable bases or complexes to which the soluble dyes can be bound. These are edible food materials that, by themselves, do not possess natural pigmentation and are predominantly water insoluble including edible food proteins such as collagen, elastin, albumin, potato and other insoluble vegetable proteins and their derivatives as well as a range of edible insoluble carbohydrates such as starches, dextrins, celluloses and complex sugars. Insoluble by^¬ products of food processing also provide useful materials including lignins, pectins, pea fibre, potato fibre and similar processing by-products.

Newman and Etherington (1974) among others have shown how dyes complexed with insoluble natural materials. In this case, the dye Remazolbrilliant Blue R was combined with collagen derived from beef hides to form an insoluble complex which can be used as an indicator of enzymatic activity where the solublisation of the protein by the enzymes will progressively release the dye back into solution. In the current applications, use is made of the fact that such compounds are pigmented, are insoluble in aqueous solution and they can be finely ground.

Such complexes can be made from any combination of food approved dye or dyes and one or more edible but insoluble materials described herein. The basic method of Rinderknecht et al (1968) is used to produce the complexes. However, the procedures are modified so that either the solvents used in the various stages of the reactions are ones that are already food use approved and/or additional steps, such as additional washing or extraction procedures, are taken so as to reduce any compound which, although not permitted as an edible foodstuff but is allowed in or in contact with foodstuffs in very low concentrations and may be used as a solvent in the manufacturing process, up to maximum permissible concentrations .

d) The formation of a suitable insoluble pigments through chemical and/or physical reactions from two or more food approved soluble dyes, lakes or coloured extracts derived from naturally occurring food materials or food approved organic or inorganic compounds . There are many examples of forming useful insoluble compounds derived from chemical and/or physical reactions between soluble materials, e.g. cyanurate-based adhesives, expanded polystyrene foams and azo dyes in the print industry. However, as far as we have been able to determine, this approach has not been used or developed specifically for the production of a water insoluble pigment for application to wet surfaces particularly from edible materials.

The advantage of such an approach is that all materials used already have food approval, they remain soluble until after their mixing and subsequent reaction and can be used in conventional print equipment of any type with minimal modification. For example, ink jet printers often use mixtures of dyes and pigments to create specific colours. We have shown that specific insoluble pigments for direct use on wet surfaces can be formed from the mixing of separate soluble components using such existing equipment .

Such an approach can also be used to generate a pigment which is food approved from individual components which may not be so approved, providing the reaction occurs prior to contact with the foodstuff and the materials resulting from the chemical and/or physical reaction are approved to contact food. An example of this is the reaction of ferric chloride and sodium hydroxide. Neither compound is currently permissible to directly contact food. However when they are mixed together under the correct physical conditions they will form a mixture of insoluble pigmented ferric oxide and ferric hydroxide (the latter rapidly dissociates into ferric oxide and water) and sodium chloride. All the resultant chemicals are food contact approved. Also, by controlling the rate of the chemical reaction by manipulating the physical conditions, the size of the resultant pigment particles can also be controlled. Such an approach also avoids several of the major problems associated with pigmented based inks, including the generation of particles that are too large and subsequently block the ink jet orifices themselves and the unevenness of pigment application due to flocculation or aggregation of particles or deterioration or loss of suspension.

Several types of chemical and/or physical actions and reactions have been shown to produce acceptable inks and while this will be familiar to those skilled in the art, they have not been applied to the production of pigment- based inks from materials approved for food use and with the very specific intention of producing an edible pigment-based ink suitable for direct application to wet surfaces of edible products.

In addition to the production of pigments suitable for direct application to wet surfaces of edible foodstuffs, such pigment based inks also need to possess a number of other properties not only to allow them to be directly and evenly applied but also adhere to the applied surfaces and to be resistant to damage after application so that any applied data, logo or information remains intact and readable by manual or machine means. This is especially problematic with wet surfaces, surfaces with a high water activity, surfaces with a high water diffusion rate, surfaces exposed to high humidities and surfaces subject to abrasion or damage through subsequent manufacturing activities.

There are many ways by means of which these can be accomplished. However for inks to be applied to food surfaces, the components that can be used to achieve the properties also have to conform to food regulations and be food approved.

For hot melt inks, the suspension and evenness of application is achieved by a combination of waxes and resins that can also provide the necessary adhesion. For pigment based inks as described herein, even when the pigment is generated immediately prior to application by- means of the various chemical and physical reactions described, there is no need for waxes or resins as the entire ink formulation is always low temperature, i.e. less than 45°C-50°C so as not to denature, destroy or damage any of the food surfaces to which it is applied.

It has been found that the necessary suspension and evenness of application properties can be obtained using various combinations of sugars where sucrose is a preferred ingredient. Changing the sugar combination and concentration and using deionised water (with or without other food approved solvents) allows for a wide range of pigment densities, weights and concentrations. The practical concentration of sugar is in the range 2%-30% with a preferred range of 5%-20%

Depending on the properties of the compound used for pigment, it may be necessary to include a dispersant and/or a surface tension modifier, especially if the particles are ionically charged although it has been found that most organic and inorganic pigments derived from the ingredients previously detailed are charge neutral and do not need dispersants or surface tension modifiers. It has been found that the sucrose solution and the use of physical techniques, such as blending and ultrasonic mixing in the preparation stages, keep the particles adequately separate and evenly suspended. Effective adhesion of pigment particles to the applied surface is essential. In many ink applications, this is simply achieved through evaporation of the solvent carrying the dye or pigment. In other applications where edible dyes are used, gums and resins provide the means of adhesion through a change of state from liquid to solid on cooling. However such materials only adhere satisfactorily where the food surface is relatively dry, e.g. eggs and/or lipophilic, e.g. cheese.

US Patent 6,148,249 teaches that in applications where surfaces are neither dry and/or hydrophilic, materials such as gelatin or alginates provide better adhesion and they also function as protective barriers against water diffusion. However they have a major drawback in that while they work well on cold or cool (below 15°C) surfaces, they remain liquid when applied to warmer surfaces such as meat carcasses (30°C-38°C). They also require considerable heat to dissolve them initially.

We have found that compounds such as seeweed extract, agar and especially carraghenan function better for wet surface applications. They are liquid at much lower temperatures than gelatin, alginate, gums and resins. They also solidify at much higher temperatures, especially those found in food manufacturing establishments such as abattoirs and primal boning plants. This has the added advantage that the ink formulation remains liquid under most conditions prior to application and therefore makes the printing process much less complicated. The preferred adhesive is carraghenan in the range 0.5%-60% with a preferred range of 2%-25%. The selected range has to be sufficiently wide as the wetness and temperature of the edible surfaces can vary tremendously as can the subsequent rate and degree of moisture ingress.

In hot melt inks, the combination of resins and gums solidify as they cool providing varying degrees of protection to the applied ink mark. They rely on a change of state (usually from liquid to solid) to generate both adhesive and protective function. However, with time the diffusion of moisture from either the product and/or the surrounding atmosphere will cause the gums and resins to break down and allow this ingress of moisture to destroy the integrity of the applied ink with the result that it will bleed into the surrounding surfaces. Initially there will be a loss of clarity in any ink mark - eventually it will become illegible. Additionally, the presence of moisture can also cause the applied ink mark to slip or distort resulting in loss of readability.

The edible pigment-based inks described herein rely on a change in composition of the ink, primarily a full or partial evaporation of solvents and dispersants within the ink composition, to leave a solid residue of ink droplets. Once the solvents have evaporated, because the ink is a water insoluble pigment, ingress of moisture from any source will have no to minimal effect on the integrity of the ink and therefore to the longevity and/or clarity of any applied mark or logo.

Additionally, the use of carraghenan (or compounds with similar properties) in the ink formulation will minimize bleeding of applied ink, as it is capable of absorbing considerable amounts of moisture without changing state or structural breakdown.

We have also shown in US Patent 6,148,249 that application of compounds such as gelatin and alginate over the applied ink which can be either a pigment, dye or lake, upon cooling, form a strong, resilient barrier within which the applied ink pigment is substantially protected against many forms of damage that may occur during further processing, handling and packaging of the edible foodstuff. But for best results, the gelatin (or similar barrier compound) needs to be applied when the product has essentially cooled to 12°C or less so that solidification of the barrier compound occurs almost immediately on application.

However, we have discovered that the use of carraghenan (and similar products) in addition to its use as an adhesive and to minimize any ink bleed or movement from its applied location, also functions well as a protective barrier. We have shown that applying the carragheenan immediately before or after the application of the ink makes little difference to its protective capabilities. If applied before the ink, pigment based inks adhere strongly to the carragheenan and this further strengthens as the ink dries and the caragheenan 'sets' . If applied after ink application, the carraghenan appears to surround the individual ink droplets as well as cover them, providing a continuous protective barrier. In both cases, the carragheenan is applied as a sprayed thin coating at a concentration of between 2% and 20% in a solution of either water or a water/ethanol mixture; the preferred option is to dissolve the carragheenan in the minimum volume of a warm water solution^' (50°C-60°C) and then add warm (35°C-45°C) ethanol. This promotes rapid evaporation and solidification of the carragheenan upon application.

However, the preferred mode of action is to utilize the carragheenan within the pigmented ink formulation so that its protective and adhesive properties are applied simultaneously. If used within the ink formulation, its concentration will have been previously determined by the desired properties of the ink formulation in relation to the properties and characteristics of the surface to which it is to be applied.

When used within the ink formulation on very wet surfaces and/or in very high moisture environments, a further thin application after the application of the ink mixture has been shown to enhance the protective functions.

While any of the pigmented components or mixtures of components detailed herein can be used to provide the necessary solid pigment, many of these materials are extremely hard, resilient and abrasive when used within ink jet printers and can result in accelerated ^Λwear and tear' of components where there is contact between pigment and ink jet surfaces, especially the ink pump and exit jets/nozzles. However, such components of ink jet printers can be constructed of hardened or more resistant materials and as such are not limiting factors in the application or use of edible pigment- based inks.

Examples

The following examples are shown merely as illustrations as to how each group of pigmented, edible materials can be used as the basis for edible, pigmented, liquid inks for use on a variety of wet surfaces or in high moisture environments . They are not meant in any way to limit either materials used, or their methods of preparation or their subsequent application.

Example^' 1: Production of an edible ink from naturally occurring inorganic compounds possessing natural pigmentation and insoluble or virtually insoluble in water or edible solvents .

Ferric Oxide in ANALAR™ form, obtained from BDH, UK. is suspended in a suitable volume of warm (50⁰C) deionised water and suspension is allowed to continue for at least 30 minutes. The pigment is filtered or centrifuged. It is then resuspended in a food grade ethanol solution several times or until there is no colour in the alcohol. The pigment is again filtered. It is then milled in stages through reducing sieve sizes until the finished product is reduced to a size that can be used in the ink printer without causing blockages in the jets, typically 10 microns or less.

The finished product can now be dried in filtered air and stored as a dry powder away from light or it can be formulated into a finished ink product. A typical formulation for application to a wet surface such as a carcass would comprise: finely milled Ferric Oxide, as previously prepared, is gradually added to a solution containing sucrose and carraghenan in a minimum amount of water with the balance being ethanol, so that sucrose to a final concentration of 20% and carraghenan to a final concentration of 10% is obtained. The mixture is vigorously agitated during preparation using manual and/or mechanical means. Because of the density of the solution, the particles of pigment Ferric Oxide remain evenly suspended in the mixture. While not essential, an edible surfactant such as lecithin or food approved polypropylene glycols, at a rate of 1% to 10% can be used to further enhance suspension properties of the edible pigmented ink especially the prevention of clumping. Ionic compounds are essentially absent and this prevents the reaction of the ferric oxide to form pigmented soluble compounds which can taint the ink mixture and reduce the contrast between the pigment and background once applied to the surfaces. It also minimizes or eliminates oxidation and the need for anti-oxidants in the formulation. The prepared mixture is stored in containers impervious to light.

Although not essential, agitation prior to use further helps to ensure even dispersion and application.

Example 2: Production of an edible ink from naturally occurring compounds possessing natural pigmentation derived from organic sources and insoluble or virtually insoluble in water or edible solvents.

Coffee beans, from a food approved source, are frozen and then milled to a fine powder. They are then suspended by agitation in a suitable volume of hot

(70⁰C) deionised water and the suspension is allowed to continue for at least 30 minutes. This will extract most of the water-soluble compounds. The pigment is filtered or centrifuged and the process repeated until there is no or minimal pigment in the solution. The process is then repeated in warm (40⁰C) food grade ethanol. This removes any residual pigments soluble in alcohol. It is then resuspended in a food grade ethanol solution several times or until there is no colour in the alcohol. The pigment is again filtered. It is then milled in stages through reducing sieve sizes until the finished product is reduced to a size that can be used in the ink printer without causing blockages in the jets, typically 10 microns or less.

The finished product can now be dried in filtered air and stored as a dry powder away from light or it can be formulated into a finished ink product. A typical formulation for application to a wet surface such as a carcass would comprise: finely milled coffee grounds, as previously prepared, is gradually added to a solution containing sucrose and carraghenan in a minimal volume of deionised water with the balance being ethanol, so that sucrose to a final concentration of 20% and carraghenan to a final concentration of 10% is obtained. The mixture is vigourously agitated during preparation using manual and/or mechanical means. Because of the density of the solution, the particles of pigment coffed grounds remain evenly suspended in the mixture. While not essential, an edible surfactant such as lecithin or food approved polypropylene glycols, at a rate of 1% to 10% can be used to further enhance suspension properties of the edible pigmented ink especially the prevention of clumping. Ionic compounds are essential absent and this prevents further reaction between the components to form pigmented soluble compounds which can taint the ink mixture and reduce the contrast between the pigment and background once applied to the surfaces. It also minimizes or eliminates oxidation and the need for anti-oxidants in the formulation. The prepared mixture is stored in containers impervious to light.

Although not essential, agitation prior to use further helps to ensure even dispersion and application.

Example 3: Pigment complexes developed from combining food approved dyes and/or lakes and/or naturally occurring pigments to organic and/or inorganic insoluble or virtually insoluble compounds possessing natural pigmentation but derived from organic sources.

Brilliant Blue FCF is dissolved in the minimum amount of deionised water necessary for complete solublisation. Food grade collagen derived from beef hides is chilled to

-40⁰C and pre-ground in a food grade mill. The fine collagen powder is slowly added to the dissolved pigment with vigorous agitation and the two are combined using the method of Rinderknecht et al. After the combination reaction is complete, the product is sequentially washed in a variety of food approved solvents and vacuum filtered until there is no visible dye in the discarded diluents. At the end of the process, the batch is sampled using a Gas Chromatograph to ensure that any residual solvents are at or below maximum allowable concentrations for food use.

The pigmented complex is now air dried, then freeze dried before being milled in stages through decending sieve mesh sizes until the finished product is reduced to a size that can be used in the ink printer without causing blockages in the jets typically 10 microns or less.

Example 4: The formation of a suitable insoluble pigment through chemical and/or physical reactions from two or more food approved soluble dyes, lakes or coloured extracts derived from naturally occurring food materials or food approved inorganic compounds. Ferric chloride and sodium hydroxide are dissolved in deionised water to produce separate solutions; optimum solution strength is 5 Molar or greater as minimum water is required to produce a final ink formulation with the correct properties. Care should be taken not to allow super saturation as this will lead to precipitation as operating temperatures fall. The two solutions are then mixed in a ratio close to their molecular weights. To ensure reactions go to completion and all resulting components are food approved, the ferric chloride is dissolved to a final concentration in deionised water containing 1 Molar Hydrochloric acid and Sodium Hydroxide is added at 5% over volume relative to its molecular weight. When they are mixed together under the correct physical conditions they will form a mixture of insoluble pigmented ferric oxide and ferric hydroxide (the latter rapidly dissociates into insoluble ferric oxide and water) and sodium chloride. The reaction takes place under constant agitation. When complete, this mixture is then added to the other ink components so that a final concentration of 20% sucrose and 10% carraghenan is obtained. All the resultant chemicals are food contact approved. Also, by controlling the rate of the chemical reaction by manipulating the physical conditions, the- size of the resultant pigment particles formed can also be controlled.

Example 5: Methods of and apparatus for pigment marking

While the principle application of these edible pigments is to damp and wet surfaces using ink jet printers, it should also be obvious to those skilled in the art that any of the edible pigments described herein can be used in almost any marking apparatus with minimal modification. Where the ink application is conventionally a dry process, e.g. laser printing, the stored dry pigment can be mixed with whatever compounds are necessary to enable both the electrostatic charge to be generated and the pigment complex to become ^λset' after application. For edible applications, all components added to the pigment complex must be approved for food, medical or pharmaceutical applications.

However, the primary and intended method of use is in ink jet printers. As has been previously detailed, the pigmented complexes described are stable, liquid suspensions of insoluble pigmented particles in mixtures of other chemicals to ensure even distribution, firm adhesion to moist, damp or wet surfaces, rapid drying or setting even in high moisture environments and the formation of protective barriers against moisture ingress and physical damage once applied. All the components of the mixture are fully approved for edible application in food, medical or pharmaceutical use.

As such, for almost all ink jet applications they can be used in ink jet apparatus without modification or adaptation. The major exception to this is inks formed from the mixing of two soluble components to form an insoluble component that will act as the ink pigment.

The simplest passive method using these pigments is by undertaking the formation of the insoluble component and mixing with other ink components in a separate vessel and then connect to the ink jet printer immediately prior to use. However, an alternative active method is to form the pigments during the printing cycle and then mixing these reacting components with the other ink components immediately before being expelled through the ink jet orifices on to the product. This will ensure that the formed insoluble particles will always be below the maximum practical size and this will minimize 'wear and tear' on the most vulnerable of the ink jet physical components . It has also been found that dividing the components of the ink which provide adhesive and protective properties into 3 separate volumes and applying one volume immediately preceding the application of the pigment jet and applying the third volume immediately after the application of the pigment jet ensures that the pigment droplets are sandwiched between two very thin adhesive and protective layers, optimising protection from any ingress of moisture from the product and/or the processing environment.

We have carried out practical tests using ink jet printers to apply patterns of dots to meat and fat surfaces. Tests using various compositions of the present invention have produced clear, distinct patterns.

In comparative tests using prior art compositions, the patterns have shown evidence of blurring of dots, and lesser stability over time.

References cited

US Patent Documents Newman, P. B., US 6,148,249 Drouillard, G. and Kanner, R.W, . US 5,660,747 Wiedenmann, E., US Patent Application 20050276887 Naivar, K., US 5,992,305

Gustaesson, S., US Patent Application 20020009523 Drouillard, G., US Patent Application 20050226975 Bolton, E. T. and Dey, N. D., US 4,133,294 Winkler, B., US 3,961,082

Reitnauer, A. and Lambert, D., US Patent Application 20050158434

Other References

Newman, P. B. and Etherington, D.J. ^XA convenient automated method for the determination of proteolytic enzymes, Analytical Biochemistry 57, 347-355, (1974) Rinderknecht, H, Geokas, M. C, Silverman, P. and Haverback, B. J., R, Colorimetric Protease Assay at 595 nm using Remazol Brilliant Blue' Clinica Chimica Acta, 21, 197, (1968)

Claims

1. An edible ink composition comprising

(a) a particulate pigment which is insoluble in water; and

(b) a vehicle comprising a solution of a food- permitted sugar in a food-permitted solvent comprising water.

2. A composition according to claim 1 wherein the particulate pigment comprises a food material.

3. A composition according to claim 2 wherein the food material is an insoluble residue resulting from the extraction of soluble components from an initial food material .

4. A composition according to claim 3 wherein the extracted components are soluble in water and/or ethanol.

5. A composition according to claim 3 or 4 wherein the initial food material is selected from saffron, turmeric, paprika, mustard seed, pepper corns, chili pepper skins or seeds, vanilla pods, cinnamon, nutmeg, pimento, cardamom seeds, jalapeno peppers, coffee beans, cocoa beans and/or pods, carrots, beetroot, nut 'shells, seed pods, seeds and skins from fruits and vegetables, and edible red and brown seaweed.

6. A composition according to any preceding claim wherein the pigment is a complex formed from an insoluble component and a coloured soluble component.

7. A composition according to claim 1 wherein the particulate pigment comprises an insoluble inorganic compound .

8. A composition according to claim 7 wherein the compound is selected from ferric oxide, ferrous carbonate, iron salts, copper carbonate, copper oxide, copper hydroxide, cobalt carbonate, cobalt oxide, iodine, calcium oxide, calcium carbonate, calcium sulphate, magnesium oxide, magnesium silicate, pigmented manganese salts, nickel, sodium bicarbonate, stannous chloride, titanium dioxide, zinc carbonate, zinc oxide and talc.

9. A composition according to any preceding claim wherein the solvent includes a food-permitted volatile water-miscible organic solvent.

10. A composition according to claim 9 wherein the organic solvent is a monohydric alcohol.

11. A composition according to claim 10 wherein the alcohol is ethanol.

12. A composition according to claim 9, 10 or 11 wherein water is a minor component of the solvent.

13. A composition according to claim 12 wherein the solvent contains 5-40% water and 95-60% v/v of organic solvent (s) .

14. A composition according to any preceding claim wherein the sugar comprises sucrose.

15. A composition according to any preceding claim wherein the sugar comprises one or more food-permitted hexose and/or pentose and/or disaccharide .

16. A composition according to any preceding claim containing a gel-forming component.

17. A composition according to claim 16 wherein the gel- forming component is selected from carragheenan, agar, gelatine, and alginates.

18. A composition according to claim 17 wherein the gel- forming component is carragheenan.

19. A method of producing an edible ink composition comprising mixing together (a) a particulate pigment which is insoluble in water; and b) a vehicle comprising a solution of a food-permitted sugar in a food-permitted solvent comprising water.

20. A method according to claim 19 wherein the composition is as defined in any of claims 2-18.

21. A method according to claim 20 including an initial step of providing an insoluble food material by extracting soluble components from an initial food material using one or more food-permitted liquids as extractants; said insoluble food material being used as said pigment or as a component thereof.

22. A method according to claim 21 wherein said extractant (s) comprise water.

23. A method according to claim 21 or 22 wherein said extractant (s) comprise ethanol.

24. A method according to claim 20, 21 or 22 including a step of producing said pigment by complexing an insoluble component with a coloured soluble component.

25. A method according to claim 19 or 20 including a process of producing said pigment which comprises mixing two or more water-soluble inorganic compounds which interact to produce an insoluble particulate material.

26. A method of marking a substrate comprising a step of applying to a surface portion of the substrate an edible ink composition comprising

(a) a particulate pigment which is insoluble in water; and

(b) a vehicle comprising a solution of a food- permitted sugar in a food-permitted solvent comprising water .

27. A method according to claim 26 wherein the composition is according to any of claims 2-18.

28. A method according to claim 26 or 27 including a preliminary process of producing the composition by the method of any of claims 19-25.

29. A method according to any of claims 26-28 wherein the substrate is a foodstuff.

30. A method according to any of claims 26-29 wherein said substrate surface portion is wet.

31. A method according to any of claims 26-29 wherein said substrate surface portion has a high water activity and/or is present in a region of high humidity.

32. A method according to claim 30 or 31 wherein the , substrate is meat or a meat product.

33. A method according to claim 30 or 31 wherein the substrate is meat.

34. Α method according to claim 30 or 31 wherein the substrate is a fruit, vegetable or portion of a fruit or vegetable .

35. A method according to any of claims 26-34 wherein the composition is applied using an ink jet printer.