Technical field of the invention

The present invention relates to a process for producing coated frozen confections having a decorated pattern printed onto the coating.

Background to the invention

Frozen confections which consist of ice cream, frozen yoghurt, water ice or the like coated with chocolate or other coatings are popular products. Coated stick and bar products are usually produced by dipping or enrobing pieces of ice cream in a coating material. The appearance of such products is a significant factor in their appeal to consumers and efforts have therefore been made to find methods for making products which are not only coated, but that are also decorated with a pattern, image or logo.

EP 1767099 discloses a process for stamping a pattern onto a coated frozen confection by bringing a stamping surface which is resiliency mounted on a support into contact with the coated frozen confection. However, stamping can only provide contrast in relief, whereas it would be desirable to produce patterns which are coloured.

WO 04 / 003089 discloses a method for ink-jet printing onto edible products such as baked goods, biscuits and cakes, cookies, nuts, chocolates, cheeses, crackers and chips, pastries, puddings and mousses, ice creams and creams, pet food and pet treats, main meal snacks, cereals, and pharmaceutical tablets. The ink consists of a fat or wax base, a water-soluble or water-dispersible colorant and a carrier for the colorant. The carrier is able to disperse or dissolve the colorant, and is also compatible with the fat / wax phase. However, there are particular difficulties with printing images onto chocolate-coated frozen confections because of the non-porous nature of the chocolate, the need for contrast over the chocolate (which is typically brown in colour) and especially the fact that - unlike ambient chocolate-coated confections - the surface of the chocolate onto which the image is to be printed it is at a low temperature. This usually results in condensation forming on the surface of the chocolate, which results slow drying ink and in the image becoming smeared.

Therefore, there is a need for an improved method for decorating coated frozen confection products. Brief description of the invention

We have now developed a new process for producing coated frozen confection products having an image, pattern, logo or other decoration printed on the coating. Accordingly, in a first aspect the present invention provides a process for producing a decorated coated frozen confection product, the process comprising:

• applying a layer of a fat-based coating material to a frozen confection; and

• ink-jet printing a fat-based ink onto the coated frozen confection to form a pattern;

• wherein the fat-base of the ink is a fat or blend of fats having a N 10 (i.e. % of solid fat at 10 ^° C) value of at least 70, preferably at least 80.

We have found that by using an ink based on a fat having an N10 value of at least 70, the above problems are overcome. Firstly, these fats have a fast crystallization rate, which results in an ink which is waterproof, is not effected by condensation on the surface of frozen confection product, dries quickly, and minimises the problem of smearing.

Suitable fats include hardened palm oils such as PK39 (fully hardened palm kernel oil with a slip melting point of 39 ^° C), P058 (fully hardened palm oil with a slip melting point of 58 ^° C), inES44 (an inter-esterified blend of 60 wt% P058 and 40 wt% PK39), inES48 (an inter-esterified blend of 65 wt% multi-fractionated palm stearin IV12 and 35 wt% PK39) and inES55 (an inter-esterified blend of 60 wt% multi-fractionated palm stearin 141V 40 wt% shea stearin), and dfPOs58 (a dry fractionated palm oil stearin with a slip melting point of 58 ^° C).

The ink should be liquid in order to be ink-jetted, thus it is at an elevated temperature during printing. At the printing temperature the ink has a viscosity in the range 2 to 40cP, preferably 3 to 30cP, most preferably 5 to 20cP and a surface tension in the range 20 mN/m to 50 mN/m, preferably 25 mN/m to 45 mN/m, most preferably 30 mN/m to 40 mN/m.

Preferably the coating is a fat based coating, such as chocolate and chocolate analogues (i.e. chocolate-like materials made using fats other than cocoa butter). Preferably the coating material is applied by dipping the frozen confection into a bath of the coating material.

Preferably the ink comprises saturated monoglyceride in an amount of up to 5wt%. We have found that adding saturated monoglyceride can increase the fat crystallisation rate, and hence the drying speed of the ink.

Preferably the ink contains an oil-soluble colourant, for example copper chlorophyll extract or lutein extract. Preferably the colour has low solubility in water, since this means that the printed pattern is waterproof, hence any condensation that forms on the cold surface of the coated frozen confection does not cause the pattern to smear.

In one embodiment, the ink further comprises functional ingredients such as vitamins or flavours. The functional ingredients can be dissolved or suspended in the ink.

Description of drawings

The present invention will be further described by reference to the figures wherein: Figure 1 shows a decorated frozen confection produced according to the process of the present invention.

Detailed description of the invention

All percentages, unless otherwise stated, refer to the percentage by weight, with the exception of percentages cited in relation to the overrun.

As used herein, frozen confection means an edible confection made by freezing a mix of ingredients which includes water. Frozen confections typically contain fat, nonfat milk solids and sugars, together with other minor ingredients such as stabilisers, emulsifiers, colours and flavourings. Preferred frozen confections include ice cream, frozen yoghurt, sorbet, sherbet, milk ice and the like. Water ices and fruit ices are another preferred frozen confection but these typically contain less fat and non-fat milk solids. These frozen confections can be prepared using known techniques. Frozen confections are typically aerated. The term aeration means that gas has been incorporated into a product to form air cells. The gas can be any gas but is preferably, particularly in the context of food products, a food-grade gas such as air, nitrogen or carbon dioxide. The extent of the aeration can be measured in terms of the volume of the aerated product. The extent of aeration is typically defined in terms of "overrun". In the context of the present invention, % overrun is defined in volume terms as:

( volume of final aerated product - volume of unaerated mix )

Overrun (%) = x 100 volume of unaerated mix

The amount of overrun present in the frozen confection will vary depending on the desired product characteristics and is preferably at least 25%, more preferably at least 50%, more preferably still at least 75% and preferably at most 200%, more preferably at most 150%.

The frozen confections of the invention are coated with one or more coating materials. The coating materials are liquid during application to the frozen confection and subsequently solidify as their temperature drops. The frozen confections may be fully or partially coated but preferably the coating covers the whole of the outer surface. In a preferred embodiment the coating materials are fat-based materials, such as chocolate and / or chocolate analogues (i.e. chocolate-like materials made using fats other than cocoa butter). In another embodiment the coating materials are water-based, for example the frozen confection may be coated with a water ice, milk ice or sorbet type coating such as that used on Solero™ products. The invention is, however, not limited to these types of coating material and any coating material suitable for coating frozen confections may be used.

The coating material can be applied to the frozen confection using known techniques such as: spraying the coating material onto the surface of the frozen confection; passing the frozen confection through a falling curtain of the coating material; pouring the coating material directly onto the surface of the frozen confection; or other such coating methods. In a preferred embodiment the frozen confection is dipped into the coating material.

The amount of the coating material used to coat the frozen confections, and hence the thickness of the coating, depends upon the desired product characteristics of the coated frozen confection. For example, stick-based frozen confections, as typified by Magnum™ products, have a relatively thick coating and the weight ratio of coating material to frozen confection is about 1 :3. The present invention is suitable for products with both thick coatings and for products with thinner, more delicate coatings and so the weight ratio of coating material to frozen confection is preferably from 1 : 100 to 1 :2, more preferably from 1 : 10 to 1 :3.

The appearance of coated frozen confections is a significant factor in their appeal to consumers and methods for making products which are not only coated, but that are also decorated with a pattern, image or logo have been developed. Such decoration techniques include moulding frozen confections such that the surface of the confection or the coating layer itself has an appealing texture or pattern. Embossing is another technique whereby a stamp is used to impress a pattern into the coating layer. In addition to techniques for physically altering the surface of the coating to provide decoration, other approaches have attempted to place decorations on top of the coating itself. For example, transfers have been used wherein a decoration is applied to the surface of a support layer and that surface is then contacted with the coating thus transferring the decoration onto the frozen confections. The disadvantages associated with these methods of decoration includes the need for direct surface contact between the stamp and the chocolate surface, the risk of damaging the chocolate surface during the process and consequent marring of the decorative feature, severe limitations on the level of detail and colour obtainable for the decorative feature, and the lack of flexibility in changing the form of the decorative feature each time requiring manufacture of new stamps and their fitting. Printing techniques such as contact printing are also unsuitable because the contact between the printing apparatus and the frozen confection can cause unwanted deformations in the surface of the product and smearing due to interaction between the surface of the product and the printing apparatus. Given the limitations of these techniques, it would be desirable to employ alternative means for applying decorations to the coating.

One such alternative means for applying decorative features to coated frozen confections is to use ink jet printing. In ink jet printing, liquid ink droplets with volumes typically in the range of 10 to 100 pL are generated and placed on a substrate. The technology uses two mechanisms to generate and position the droplets, namely continuous inkjet (CIJ) and drop-on-demand (DOD).

In CIJ a fine liquid ink stream breaks up into a continuous train of liquid droplets through Rayleigh instability. Each droplet is charged at the point of generation and can be steered using electric or magnetic fields. If printing is not required, the droplets are captured and rejected or recycled. In DOD droplets are generated as and when required through generating a pressure pulse in a liquid reservoir. The pressure pulse can be generated by a piezoelectric actuator (piezoelectric ink-jet) or by a heater boiling a small quantity of liquid ink, the resulting vapour cavity expansion generating the pressure pulse (thermal inkjet or bubble jet). For applying decorative features to coated frozen confections, DOD is preferable as CIJ requires the ink to have some limited electrical conductivity and the printer must have a mechanism to capture and possibly recycle unused ink. Furthermore piezoelectric ink-jet is preferred over thermal inkjet or bubble jet because the latter needs the ink to have a high vapour pressure and low boiling temperature. In addition to these approached, any other suitable apparatus can be used for applying ink to the coating provided that the apparatus is able to heat the ink to ensure suitable viscosity and surface tension for printing and application.

The advantages that ink jet printing brings are speed, flexibility, ability to reproduce fine detail, and that it is a contactless means for printing. However, there are critical requirements for the ink that be used. The rheology must be correct for printing, it must dry sufficiently quickly, it must be water-proof due to the formation of condensation on the surface of the cold ice cream product, and it must not bleed into the chocolate coating.

Inks typically comprise a carrier, a binder, a colourant, and often a solvent. However, we have now found that a fat based ink that comprises a fat base which acts as both a carrier and a binder is suitable for using in ink jet printing apparatus to apply decorative features to coated frozen confections. This ink may optionally contain one or more colourants and preferably contains less than 1 wt% solvent, more preferably less than 0.5 wt%, more preferably still less than 0.05 wt%, yet more preferably still 0.01 wt%, and most preferably less than 0.001 wt%.

In general, for fat-based inks any fats can be used for such inks provided that the fat is liquid at the printing temperature. However, it has surprisingly been found that fats with a particular N 10 value are particularly suitable for applying decorative features to coated frozen confections using ink jet printing. In particular the fats have a N10 value of at least 70, preferably at least 80, more preferably at least 90, more preferably still at least 95, most preferably at least 99. The N10 value of a fat is the percentage of the fat that is solid at 10 ^° C. The N10 value of various fats are well characterised and can also be readily determined using the pulsed Nuclear Magnetic Rexonance method that is set out by the International Standards Organisation in ISO 8292:1991 (E).

Suitable and preferred fats which have a N10 of at least 75 include coconut oil, cocoa butter, shea stearin, palm oil, palm kernel oil, palm stearin oil, hardened palm oil, hardened palm kernel oil, multi fractionated palm oil stearin (mfPOs), dry fractionated palm oil stearin (dfPOs), and mixtures thereof.

As used herein, hardened means that under high temperature conditions and by means of a catalyst, unsaturated bounds in the fatty acid chain have been changed into saturated ones by the addition of hydrogen or the cis-unsaturated form is converted in a trans-unsaturated form. Fully hardened refers to an oil that has been hydrogenated to the point when almost no trans fat remains. Resulting fat consequently has an even higher melting point than a partially hydrogenated one. Inter-esterified means that higher temperature and a catalyst have been used to rearrange the fatty acids on the glycerol molecule. Dry fractionated fats are the result of a process based on differences in melting points of the component triglycerides and partial glycerides. The process is a thermomechanical separation process where the high and low melting triglycerides are separated by partial crystallization, followed by filtration. Multi fractionated oils are obtained through by separating oils in successive stages or my combining two or more components of the same starting material during the oil refining process.

Particularly preferred fats are PK39 (a fully hardened palm kernel oil with a slip melting point of 39 ^° C), P058 (a fully hardened palm oil with a slip melting point of 58 ^° C), inES44 (an inter-esterified blend of 60 wt% P058 and 40 wt% PK39), inES48 (an inter-esterified blend of 65 wt% multi-fractionated palm stearin IV12 and 35 wt% PK39), inES55 (an inter-esterified blend of 60 wt% multi-fractionated palm stearin IV 14 and 40 wt% shea stearin), dfPOs58 (a dry fractionated palm oil stearin with a slip melting point of 58 ^° C), or mixtures thereof.

The slip melting point is a conventional definition of the melting point of a fat and is determined by casting a 10 mm column of the solid fat in a glass tube with an internal diameter of about 1 mm and a length of about 80 mm. The tune is then immersed in a temperature-controlled water bath. The slip point is the temperature at which the column of the solid fat begins to rise in the tube due to buoyancy, and because the outside surface of the solid is molten. The fat based used in the process of the present invention preferably contains at least 80wt% of a fat having a N10 value of at least 70, more preferably at least 90wt%, more preferably still at least 95wt%, most preferably 99wt%.

In the process of the present invention the ink must be liquid enough for to enter the print head and be ejected in the ink jet printing process. Preferably the temperature of the ink is therefore in the range of 25 to 130°C, more preferably 55 to 1 10°C, more preferably still 60 to 90°C, most preferably 65 to 75°C.

At the printing temperature, the ink preferably has a viscosity of from 2 to 40 cP, more preferably from 3 to 30 cP, most preferably 5 to 20 cP

At the printing temperature, the ink also preferably has a surface tension of from 20 to 50 mN/m, more preferably from 25 to 45 mN/m, most preferably from 30 to 40 mN/m.

The ink may also contain oil soluble colourants. As used herein, "oil soluble" means that at least 90wt% of the colourant used in the ink is dissolved in the fat ink. The oil- soluble colourant is also preferably insoluble in water such that the printed pattern is waterproof and any condensation which forms on the cold surface of the coated frozen confection does not cause the pattern to smear. Examples of suitable oil soluble colourants include copper chlorophyll extract and lutein extract. Preferably the colourants are present in an amount of at most 20wt% of the fat based ink, more preferably at most 10 wt%, more preferably still at most 5 wt%, yet more preferably still at most 1wt%. In another embodiment the ink contains no colourant. Typically, in fat based inks, the colourant must be first solubilised in a carrier prior to mixing with the fat base. These carriers are typically solvents and we have found that their presence in the ink greatly reduces the speed at which the ink dries and hence the ink is particularly susceptible to smearing. The use of oil soluble colourants allows for reductions in the amount of carrier present and further enhances the performance of the ink and minimises the problem of smearing. Preferably the ink comprises at most 10wt% of a carrier, more preferably at most 5wt%, more preferably still at most 2wt%, yet more preferably still at most 1wt%, most preferably none.

The ink may also contain saturated monoglycerides such as DIMODAN® HP K-A, a distilled monoglyceride made from edible, refined, hydrogenated palm oil. The presence of saturated monoglycerides as been found to increase the crystallisation rate of the fat based ink and can therefore preferably be present in an amount of at most 5wt% of the fat based ink, more preferably at most 2wt%, more preferably still at most 1wt%, most preferably at most 0.5wt%.

In a further embodiment, the ink may comprise functional ingredients such as vitamins or flavours. The functional ingredients can be dissolved or suspended in the ink and may be present in an amount of at most 1wt% of the ink, preferably at most 0.5wt%, more preferably still at most 0.05 wt%.

In the process according to the invention the fat based ink is preferably heated to a temperature of from 25-130°C, more preferably 55-1 10°C, more preferably still 60- 90°C, most preferably 65-75°C such that the ink has a viscosity of preferably from 2 to 40 cP, preferably from 3 to 30 cP, most preferably from 5 to 20 cP and a surface tension of from preferably 20 to 50 mN/m, more preferably from 25 to 45 mN/m, most preferably from 30 to 40 mN/m. Any print head that is capable of ink jet printing ink having such viscosity and surface tension may be used. Such print heads include the Dimatix Galaxy PH 256/80 HM and Dimatix Q-Class Emerald Printhead.

The process according to the present invention wherein the fat-base of the ink is a fat or blend of fats having a N10 value of at least 70 surprisingly provides an enhanced performance in terms of the speed at which that ink dries and the rate at which the fat crystallises. Furthermore, the decoration applied to the frozen confection has enhanced waterproofness and suffers from reduced smearing. Hence, the process of the invention allows for the application of very complex decorations in the form of random patterns, detailed designs, images, highly defined text, and so on to be applied. By employing a plurality of differently coloured inks the process is also able to provide multi-coloured decorations.

The present invention will now be further described with reference to the following non-limiting examples.

Examples

An ink was formulated according to the composition shown in Table 1.

Ingredient wt% inES48 (Supplier: Unimills) 98

Lutein (Supplier: Overseal Natural 2

Ingredients Ltd)

Table 1 : Ink formulation

The fat (inES48) and colorant (Lutein) were heated at 80°C in oven for approx 2 hrs to melt the fat and allow for mixing. The ink was removed from the oven, inverted 3 times to mix thoroughly and introduced into a printer cartridge attached to a Dimatix Galaxy PH 256/80 HM print head.

The viscosity and surface tension of the ink at various temperatures were measured. Viscosity was determined using a Brookfield DV-II + Viscometer with low viscosity/low volume spindle and adaptor. 18mL samples of liquid ink were transferred to a heated low volume adaptor and a heated spindle was placed in the ink. The spindle was attached to the Brookfield viscometer and left to equilibrate at the required temperature for 5 minutes. The device was then started and run for approximately 2mins and a reading was then taken. Surface tension was determined using a Torsion Balance for surface & interfacial tension with a 40mm circumference platinum Du Nouy Ring. 20mL samples of the liquid ink were placed in a glass dish and raised to the Du Nouy ring which was positioned so it was just bellow the surface of the ink. The ring was then gently raised out of the ink using the torsion balance until it released all contact wit the ink. The surface tension reading was then recorded. The results of the viscosity and surface tension analysis are shown in Table 2.

Table 2: Results of the viscosity and surface tension analysis

The ink was printed onto the surface of a standard Magnum™ frozen confection using the Dimatix Galaxy PH 256/80 HM print head to form the decoration shown in Figure 1 . It was found that the ink dried quickly and formed a very clearly defined decoration that was highly resistant to smearing and that retained its detail over a long period of time.