Method For Displaying And Selling Frozen Edible Products Field of the Invention

[0001] The present invention relates to a method for displaying and selling frozen edible products in a catering or retail outlet. In particular it relates to a method in which specific types of frozen products are used.

Background to the Invention

[0002] Selling frozen edible products, such as ice creams, sorbets, water ices, frozen milkshakes, granitas and slush ice drinks, in quick service restaurants, institutional catering facilities, petrol stations and other outlets has always presented problems. Firstly, frozen products must be stored in freezer cabinets which, owing to their size, frequently cannot be located at the point of sale where the customer makes his decision with regards to buying or not buying a product. Secondly, products must be visible and accessible to serving staff and / or customers. If frozen products are not visible, customers are likely to choose a more readily accessible alternative, for example a chilled dessert such as yoghurt which is normally displayed in an open-fronted chill cabinet or a chocolate bar from an ambient display stand.

[0003] Counter-top freezers are available that allow frozen products to be

presented to customers but these require connection to a power source and maintenance. They are also quite sizeable, due to the need to provide active refrigeration, whereas in catering environments space is usually a very scarce resource. Slush ice makers are also available, but suffer similar drawbacks. On the other hand, insulated boxes combined with passive refrigeration (e.g. cooling blocks containing eutectics) for storing and preserving frozen products are known, for example from US 3 802 220. WO 03/083386 discloses an insulated container having removable displaying and cooling means and containing frozen edible products. In operation, the insulated container, equipped with its displaying means and cooling means and filled with frozen edible products to be sold, is put on display at a point of sale, so that customers can chose and take products from said insulated container. However these insulated boxes and containers suffer from the drawback that they are unable to keep frozen products such as ice cream at sufficiently low temperatures (e.g. below about -8°C) so that the products remain acceptable to the consumer for sufficiently long times. This is inconvenient for the vendor who has to keep track of the product temperature and frequently replace the products and / or the passive cooling means. It would be preferable to only have to replace the product and / or cooling means once or twice per day at a predetermined time (e.g. the start or end of a shift), thus requiring minimal time and effort from the operator. Thus there is a need for an improved method for displaying and selling frozen products which requires only a small amount of space and minimal intervention from the vendor.

Summary of the Invention

[0004] We have now found that it is possible to display frozen edible products for 6 hours or more with good visibility and accessibility whilst requiring minimal space at the point of sale provided that the frozen product is carefully designed to optimise the temperature range over which it is acceptable to consumers, thus extending its lifetime in an insulated container. Accordingly, in a first aspect the present invention provides a method for displaying and selling frozen edible products from an insulated container equipped with passive cooling means, the method comprising placing frozen edible products which contain particles of ice or other frozen material having a size of from 0.5mm to 10mm in an insulated container which is situated at a point of sale in an ambient temperature environment.

[0005] The invention lies in the recognition that frozen products containing large particles of ice (or other frozen material), for example granita / ice slush products are suitable for consumption over a wide temperature range, compared for example to a standard ice cream or ice lolly product. Thus they may be displayed in an insulated container for a long period of time whilst retaining their acceptability to consumers. At low temperatures, i.e. soon after they have been put on display, these products are solid and can be consumed by spooning. After they have been kept in the container for several hours their temperature will have risen. Above about -6 ⁰ C normal ice creams begin to become unacceptably soft and runny; similarly ice lolly products become prone to falling off their sticks. In contrast, while products containing large ice particles change their properties as their temperature increases, this change does not result in them becoming unacceptable to consumers. As their temperature rises, the products become more liquid-like and may be consumed by sucking through a straw or by drinking (rather than by spooning), so that they become more like frozen

milk-shakes or slush drinks. The initially large frozen particles become smaller as a result of melting, but are still perceptible on consumption. Thus these products retain their icy nature and acceptability. The invention therefore allows frozen edible products to be displayed and dispensed in quick service restaurants, institutional catering facilities and other similar retail outlets which normally have very little space for a freezer at the point of sale. By carefully designing the frozen product, display times of 6 hours or longer can be achieved without requiring intervention from the vendor (e.g. monitoring the temperature, or replacing the products and / or cooling means).

[0006] Preferably the particles have a size of greater than 1 mm. Preferably the particles have a size of less than 8mm.

[0007] Preferably the particles are present in an amount of from 20 to 60 wt% of the product.

[0008] In one embodiment, the particles have an average size of from 1 to 2mm and are present in an amount of from 30 to 40 wt% of the product.

[0009] In another embodiment, the particles have an average size of from 5 to 8mm and are present in an amount of from 50 to 60 wt% of the product.

[0010] Preferably the passive cooling means comprises a eutectic material, more preferably one having a eutectic temperature in the range -5 to -25 ⁰ C, even more preferably -8 to -2O ⁰ C. Most preferably the passive cooling means is provided in the form of pre-frozen blocks containing the eutectic material. In a particularly preferred embodiment, the blocks can be removed from the insulated container without needing to remove the products from the container.

[0011] In one embodiment the insulated container is separated into two or more separate compartments. [0012] Preferably the point of sale is located in a restaurant, cafe, institutional catering facility, petrol station or other retail outlet.

[0013] Preferably the frozen edible product contains from 5 to 25 wt% of sugars.

[0014] Preferably the frozen edible product is a frozen confection such as an ice slush, a frozen milkshake or a granita.

[0015] Preferably the particles consist essentially of ice.

Detailed Description of the Invention

[0016] The various features and embodiments of the present invention, referred to in individual sections below apply, as appropriate, to other sections, mutatis mutandis. Consequently features specified in one section may be combined with features specified in other sections, as appropriate. All percentages are by weight unless otherwise specified. The invention is further described with reference to the drawings wherein:

Figure 1 represents a view of a container suitable for use in the method of the invention.

Figure 2 represents a view of a container having three separate drawer compartments suitable for use in the method of the invention.

[0017] "Frozen edible product" means a product designed for consumption which contains ice. In terms of their ingredients, the frozen edible products may be similar in formulation to conventional frozen products, such as ice creams, sorbets, frozen yoghurts and the like. However, the frozen edible products differ from conventional ice creams in that they contain particles of ice or other frozen material having a size of greater than 0.5mm which are large enough to be perceived individually on consumption. The products are thus granita, frozen milkshakes or ice-slush style products. The frozen edible products are normally a packaged, for example served in tubs or cups. The products are suitable for consumption over a wide temperature range. At relatively low temperatures (e.g. -10°C or below) they are spoonable, similar to conventional frozen confections. At higher temperatures (e.g. -5 to -2°C) they are drinkable.

[0018] The frozen particles can be produced from water or aqueous solutions in any suitable manner, for example by freezing drops on a drum freezer; by direct immersion of droplets in liquid nitrogen, for example as described in US 5,126,156; by moulding small ice pieces, e.g. as described in US 5,738,889; or by using a fragmented ice maker such as the Ziegra Ice machine ZBE 4000-4, ZIEGRA-Eismaschinen GmbH, Isernhagen, Germany; a fragmented ice maker is described in US 4,569,209.

[0019] In a preferred embodiment, the frozen particles consist essentially of ice.

By "consist essentially of ice" it is meant that a small amount of solids may be present, so that, for example, the ice particles are flavoured or coloured. In this case the total solids content is less than 0.5 wt%, preferably less than 0.1 wt%. However, the frozen particles need not be pure ice, but may for example be pieces of frozen fruit juice or frozen milk etc. In one embodiment, up to about 20% of the frozen particles are frozen pieces of fruit.

[0020] Frozen particles are 3-dimensional objects, often of an irregular shape.

However, methods for viewing and measuring such particles are often 2-dimensional (see below). Consequently, measurements are often made solely in one or two dimensions and converted to the required

measurement. The size of a particle can be calculated from an area size measurement by assuming a regular shape for the particle and calculating the size or volume on that basis. By "area size", we mean the maximum area as seen in the image plane (i.e. when viewed using optical imaging). Typically, the assumed regular shape is a sphere and therefore the size is 2 x V(area size/π). The frozen particle size distribution of a frozen product can be measured as follows.

[0021] All equipment, reagents and products used in sample preparation are equilibrated to the measurement temperature for at least 10 hours prior to use. Measurements are made at -1O ⁰ C and at standard pressure. A 10 g sample of the frozen product is taken and added to 50 cm ³ of a dispersing solution consisting of 20% ethanol in aqueous solution, and gently agitated for 30s or until the sample has completely dispersed into single particles. The aqueous ethanol dispersing solution can be designed to match the measurement conditions of the experimental system: see 'Concentration properties of Aqueous solutions: conversion tables' in "Handbook of Chemistry and Physics", CRC Press, Boca Raton, Florida, USA. The whole ice / ethanol / water mix is then gently poured into a 14 cm diameter petri dish, ensuring complete transfer, and again gently agitated to ensure even dispersal of the ice particles in the dish. After 2 seconds (to allow for cessation of particle movement) an image is captured of the full dish. Ten replicate samples are taken for each product.

[0022] Images can be acquired using a domestic digital camera (e.g. JVC

KY55B) with its macro-lens assembly as supplied. The camera is selected to provide sufficient magnification to reliably image particles with an area size from 0.5 mm ² to greater than 50 mm ² . For imaging, the petri dish containing the sample is placed on a black background and illuminated at low angle (Schott KL2500 LCD) to enable the frozen particles to be easily visualised as bright objects.

[0023] Image analysis is conducted using the Carl Zeiss Vision KS400 Image analysis software (Imaging Associates Ltd, 6 Avonbury Business Park, Howes Lane, Bicester, OX26 2UA) with a macro programme specifically developed to determine the area size of each particle in the image. User intervention is required to remove from the image: the edge of the petri dish, air bubbles, coincidentally connected frozen particles and any residual undispersed material. Of these features, only the apparent connection between frozen particles is relatively frequent. The 10 samples taken allow for the sizing of at least 500, and typically several thousand, particles for each product characterised. From this image analysis it is possible to calculate the range and mean of the diameters of the frozen particles.

[0024] To produce the frozen confection, the frozen particles are combined with a mix. Mixes typically contain sugars such as monosaccharides (e.g.

dextrose, fructose), disaccharides (e.g. sucrose, lactose, maltose), oligosaccharides containing from 3 to ten monosaccharide units joined in glycosidic linkage (e.g. maltotriose), corn syrups, and sugar alcohols (e.g. erythritol arabitol, xylitol, sorbitol, glycerol, mannitol, lactitol and maltitol). The amount of sugars in the mix is such that the final frozen products contain from about 5 to about 25 wt% of sugars. Mixes typically also contain other ingredients conventionally found in water ices, fruit ices and milk ices, such as fruit (for example in the form of fruit pieces, fruit juice or fruit puree) milk solids, fat, colours, flavours, stabilizers and acidifying agents.

[0025] The mix may be (partially) frozen, for example in an ice cream freezer

(scraped surface heat exchanger) before it is combined with the particles. Thus, in addition to the frozen particles, the frozen confection may also contain ice crystals. Ice crystals are typically formed during dynamic freezing of the mix (e.g. in a scraped surface heat exchanger) and are distinguished from the frozen particles by their size. The ice crystals are substantially smaller than the frozen particles, i.e. less than 0.25mm, usually less than 0.1 mm. Ice crystals formed in a scraped surface heat exchanger are typically 0.05 - 0.1 mm in size.

[0026] Alternatively, the mix may simply be chilled before it is combined with the frozen particles. The frozen particles and mix may conveniently be combined by feeding the frozen particles through a vane feeder into the mix.

[0027] The frozen particles are preferably added in an amount such that they constitute at least 20%, more preferably at least 30% by weight of the frozen confection. Preferably the frozen particles are added in an amount such that they constitute at most 70%, more preferably at most 60% by weight of the frozen confection. We have found that it is difficult to obtain a product in which the frozen particles are evenly distributed in the mix when the frozen particles are added in larger amounts.

[0028] In the method of the invention, the frozen edible products which contain the frozen particles are placed in an insulated container which is situated at a point of sale in an ambient temperature environment.

[0029] "Ambient temperature" means the normal temperature at the point of sale, i.e. room temperature if the point of sale is indoors, or the air temperature if the point of sale is outdoors, typically 15 to 30°C, such as about

20-25°C. Thus "ambient temperature environment" does not include the situation where the insulated container is located inside a freezer, cold store, chill cabinet etc.

[0030] "Insulated container" means a container having insulated walls which comprise a heat insulating material having a thermal conductivity in the range of 0.5 to 50 mWm ^'1 K ^'1 . Typically, the container is of generally cuboid shape, having 6 sides, although other shapes and configurations are possible. The insulated walls may be constructed from an insulating material encased between sheets of a material such as fibreglass, metal or plastic. The insulating material can be, for example, a closed cell foam structure such as expanded polystyrene; foam rubber, such as elastomeric nitrile rubber insulation (which has a thermal conductivity of around 30 mW m ^'1 K ^'1 ); rigid foams, such as polyurethane; a fibrous material, such as fibreglass; a vacuum sealed within a double walled container; or vacuum insulated panels, which are typically made of an open cell foam or granular structure which is enveloped and hermetically sealed into a

gas-impervious film under very low pressure. These panels have a thermal conductivity of around 5 to 10 mW m ^'1 K ^'1 . Different insulating materials can be used to construct different parts of the container. The walls are usually 5 - 50mm thick, typically about 25mm.

[0031] The passive cooling means is preferably a phase change material with a thermal capacity of between 150 and 300 kJ/ kg over a temperature range of -5 to -5O ⁰ C. Preferably it is a eutectic material, i.e. a phase change material which changes phase (melts) over a narrow temperature range, such as less than 1 or 2 ⁰ C, for example eutectics based on urea, sodium acetate or sodium chloride. The phase change material should have a phase change temperature such that the frozen edible product remains frozen and is at a suitable temperature when consumed, for example -5 ⁰ C or below, preferably, -8 ⁰ C or below.

[0032] When the cooling capacity of the passive cooling means is nearly

exhausted, or at the end of a vending period, the passive cooling means are "recharged", for example by re-freezing in a back-of-house freezer facility. The time for which the passive cooling means are refrozen must be sufficient to remove the heat absorbed by the cooling blocks during a vending period. Typically they will be refrozen overnight. The phase change temperature should be above the temperature of a typical back-of-house refrigeration facility, so that it can be refrozen conveniently, e.g. overnight or while the outlet is closed. The back of house refrigeration facility is typically a freezer or cold store at a temperature in the range -18 to -25 ⁰ C. Thus the phase change temperature is preferably -25 ⁰ C or above, more preferably -2O ⁰ C or above, such as about -10 to -15 ⁰ C.

[0033] The phase change material may be provided in the form of blocks

comprising a hollow casing containing the passive cooling means. The casing may be any suitable material, such as fibreglass or plastic. The casings are typically not completely filled with the phase change material when unfrozen, so that there is space inside the casings to allow for expansion of the phase change material on freezing. The phase change material generally does not make the products colder (since the products and phase change material may well be at the same initial temperature, i.e. that of the back-of-house freezer), but prevents the products from warming up.

[0034] Preferably blocks containing the phase change material are located on each of the inside surfaces of the container since this configuration is the most effective for maintaining low temperatures inside the container. If it is desired to minimise the amount of phase change material, the most effective location for a single block in order to maintain low temperatures is on the inside of the upper surface of the container. The blocks and products may be stacked, e.g. a block is placed on the bottom of the container, then a layer of products is placed on the block, then another block on top of the products, then a second layer of products and finally a third block on top near the upper surface of the container.

[0035] Preferably, the blocks are removable from the insulated container. More preferably, the blocks can be removed without having to remove frozen products from the container. Thus the container and products may remain in place at the point of sale while the cooling blocks are removed for refreezing and replaced with frozen ones. This allows the frozen products to be held inside the insulated container continuously for long times, e.g. for several days.

[0036] The container containing the frozen products and equipped with the

passive cooling means is situated in an ambient temperature environment at a point of sale. The frozen products are then available to be sold during a vending period. Depending on the throughput of the outlet, it may be appropriate to replace the products without replacing the passive cooling means, i.e. if the number of products sold is high so that the products are sold before the cooling capacity is exhausted, or to replace the passive cooling means, i.e. if the number of products sold is lower so that the cooling capacity is exhausted before all the products are sold.

[0037] A 6, 12 or 24 hour display time fits conveniently into sales patterns and shift operations in a quick service restaurant, which is typically open for 12 to 18 hours per day. Cooling blocks can be brought out from the

back-of-house freezer to the point of sale at the start of the vending period and need only be replaced once or twice per day, thus requiring minimal time and effort from the operator.

[0038] The thickness of the insulating material and the amount and nature of the phase change material depend on a number of factors, including the size and number of products in the container, the temperature of the

environment in which the container is placed, and the time for which the frozen products are required to be kept in the container. Heat load analysis may be employed in order to predict the thickness of the insulating material and the amount and nature of the passive cooling means required.

[0039] A thermometer for measuring the temperature of the cooling blocks and / or products, together with a display or alarm, may be included in the container so that an operator can ensure that the temperature does not go above a pre-determined upper limit (for example -2 ⁰ C). Similarly, a timer alarm may be included to ensure that the container is used for a certain period of time before the cooling blocks are replaced or re-frozen.

[0040] The container may be constructed from two (or more) parts which fit

together and which can slide relative to each other so that the length of the container can be varied to suit differently spaces at the point of sale.

[0041] Preferably at least part of the container (e.g. the lid) is transparent so that the products are visible. However, it is also possible that no part of the container is transparent, so that the products are not visible until the container is opened. In this case, images of the products are preferably shown on the outside of the container so that it is clear to consumers that the products are inside. Thus in this case the products themselves are not displayed. Nonetheless, the container achieves the function of displaying the products by means of the images.

[0042] In one embodiment, the insulated container is cuboid with a base, four walls and a lid. The front wall is openable to allow access to the products. Figure 1 is a cut-away view of a container of this embodiment with the front wall and lid not shown so that the inside of the container is visible. The insulated container 1 contains passive cooling means comprising a eutectic block 2 which is supported on rails 3 just below the lid and above the products 4. The openable front wall minimizes heat transfer whilst still providing good access to the products.

[0043] In another embodiment, the container 1 has more than one compartment, for example three separate compartments. Different types or flavours of product may be present in each compartment. Each compartment may be opened independently of the others, for example where the front wall comprises a number of doors. Having separate compartments minimizes the heat flow into the other compartments when one compartment is opened, and thereby helps to maintain the required low temperature for long times. The compartments may conveniently be formed as drawers 14 which can be slid forward in order to access the products as shown in Figure 2.

[0044] The present invention will now be further described with reference to the following examples, which are illustrative only and non-limiting.

Example 1

[0045] An insulated container having dimensions of 607mm (length) x 333mm (width) x 216mm (height) was constructed from 25mm thick vacuum insulated panels (nominal thermal conductivity of 10 mW m ^'1 K ^'1 ). A block having dimensions 480mm x 280mm x 28mm and containing 2.2 litres of frozen eutectic solution with a mass of about 2.5kg (supplied by Cool Sari) was placed inside the container just beneath the top panel, supported on plastic rails as shown in Figure 1. Two smaller blocks measuring 200 x 90 x 20mm and containing approximately 300 g of eutectic were placed adjacent to the side walls. The eutectic had a melting point of -12°C.

[0046] The container was filled with 18 200ml products comprising large ice

particles in a syrup (described in example 3 below) at an initial

temperature of about -6°C. At this temperature the products were spoonable. The container was placed in an ambient temperature environment at 25 ⁰ C. The temperatures of four of the products were measured by means of thermocouples placed at their centres and their edges. The products were found to remain below -2 ⁰ C for 21 hours. At the end of this time, the products were acceptable in terms of their

appearance, i.e. there was no significant separation of the ice particles and the liquid phase. This demonstrates that the method of the invention allows these types of frozen products to be kept in an acceptable condition for long periods of time.

Example 2

[0047] Three different frozen products were made using the following formulation.

[0048]

Table 1

[0049] Product A: a conventional soft ice cream product was produced by mixing all the above ingredients, pasteurizing and homogenizing the mix and then freezing and aerating in a standard ice cream freezer to an overrun of 100%.

[0050] Product B: a low overrun ice cream product was produced in the same way as A, except that the overrun was 5%.

[0051] Product C: a granita style product containing ice particles was produced by mixing the above ingredients, except that only 34Og of water was included. The mix was pasteurized and homogenized and then frozen in an ice cream freezer. The remaining 288g of water was frozen to form large ice particles (approximately 5mm in diameter). The ice particles were fed into the stream of partially frozen mix as it left the freezer using a fruit feeder. The resulting mixture was then passed through a size-reduction device so that the ice particles were ~ 1 mm in size. The product had an overrun of about 10%, due to incorporation of air as the ice particles were mixed in.

[0052] The products were filled into 200 ml containers and stored at -18 ⁰ C until used for testing. To test the suitability of these products for use in the method of the invention, samples were equilibrated at a number of temperatures between -9.5 and -4.O ⁰ C. The acceptability of the products at each temperature was judged by a panel of tasters. The results are given in Table 2.

[0053]

Table 2

[0054] All of the products had the same final formulation. B and C had similar overruns. Thus the different properties are solely due to the form of the ice in the products. In A and B, the ice crystals were small (< 100μm) since they were produced in the ice cream freezer. In C, a substantial amount of the ice was present in the form of large (~1 mm) particles. The results show that the product containing large ice particles (C) was acceptable at higher temperatures, corresponding to longer storage times, than the ones with the identical formulation but without large ice particles (A and B). Thus products with large ice particles enable the use of an insulated container equipped with passive cooling means for displaying and selling over long periods of time.

Example 3

[0055] A granita-style product containing large ice particles was produced as follows. A concentrated mix (syrup) having the formulation shown in table 3 was produced. The mix was pasteurized and homogenized and then passed through a standard ice cream freezer (scraped surface heat exchanger) which cooled it to approximately -7°C without aeration. At this temperature, the partially frozen mix has an ice content of about 30 wt%, in the form of small ice crystals. Large ice particles (approximately 8mm in diameter) were produced by continuously crushing ice cubes using a Power Tech crusher fitted with an 8 mm screen. The ice particles were fed into the stream of partially frozen mix as it left the freezer using a vane feeder in a 50:50 weight ratio of particles to mix. The combined product consisting of ice particles dispersed in the partially frozen mix was a flowable slurry at a temperature of about -4.0C. It was filled into 200ml containers, hardened in a blast freezer and finally stored at -18 ⁰ C until used for testing.

[0056]

Table 3

[0057] To test the suitability of these products for use in the invention, samples were equilibrated at a number of temperatures between -6.5 and -1 ⁰ C. The acceptability of the products at each temperature was judged by a panel of tasters. The results are summarized in table 4.

[0058]

Table 4

The results show that the product was acceptable over a wide range of temperatures (i.e. corresponding to long times in the method of the invention). The presence of the large ice particles means that although the nature of the product changes - from a spoonable, granita style product to a pourable ice slurry and finally to an ice-containing drink - it retains its acceptability to the consumer as a refreshing / cooling product. Thus products with large ice particles enable the use of an insulated container equipped with passive cooling means for displaying and selling over long periods of time.