A freeze-dried coffee article and a method for the production thereof

Abstract

There is provided a method for the manufacture of a plurality of freeze-dried soluble coffee articles, the method comprising: (i) providing an aqueous coffee extract comprising at least 40wt% soluble coffee solids; (ii) foaming and cooling the aqueous coffee extract to form a foamed viscous coffee extract; (iii) depositing the foamed, viscous coffee extract onto a surface to form a plurality of individual coffee articles; (iv) freezing the plurality of individual coffee articles to form a plurality of frozen coffee articles; and (v) subliming water from the plurality of frozen coffee articles under a pressure of less than 07mbar, preferably 0.1 to 0.5mbar, to form a plurality of freeze-dried soluble coffee articles, each having a mass of 0.10g or less and a colour of less than 35 La, wherein, in step (iv) the freezing of the individual coffee articles includes a low temperature annealing step whereby the coffee articles remain within a temperature range of from -15 to - 35ºC for at least 20 minutes.

Description

[0001] A freeze-dried coffee article and a method for the production thereof

[0002] The present invention relates to the provision of a freeze-dried coffee article and a composition comprising a plurality thereof. The articles are preferably of uniform shape, including dome-shaped embodiments and have a desirable colour and appearance. The articles are an alternative to a conventional freeze-dried powder for producing a beverage, but they can be made with a significantly lower energy cost without compromising the product quality or appearance.

[0003] Freeze-dried coffee is well known in the art and such products are generally considered to be a premium soluble coffee product. The drying process is typically gentler than spraydrying, with a reduced loss of volatile flavour components due to the low temperatures used. Accordingly, while it is generally more expensive to produce freeze-dried coffee than spray- dried coffee, due to the energy costs associated with the freeze-drying process, the product is generally more desirable.

[0004] A conventional freeze-drying system for preparing soluble coffee is well known in the art. Such a system takes an aqueous soluble coffee extract, typically having from 40 to 50wt% soluble coffee solids, and cools it down. The cooled coffee extract is then typically foamed, which provides a number of benefits. These include improved dissolution, colour control and the density of the final freeze-dried product. The foamed, cooled coffee extract is then loaded onto cooling trays and frozen to a temperature of less than minus 40°C and typically less than minus 50°C. The frozen material is ground to increase its surface area and then subjected to a freeze-drying process with added heat under a reduced pressure. An exemplary freeze-drying process is disclosed in EP3448166.

[0005] As a consequence of the freeze-drying process steps, the final product has a sharp fragmented structure, with edges where the frozen sheets of soluble coffee were fragmented and broken up before drying. The freeze-dried coffee has flat angular faces and generally has an open pore structure due to the water leaving the structure during the drying process (c.f. spray-drying). The conventional freeze-drying process produces a large amount of fines, particularly from the grinding step, which need to be sorted out of the fragmented material and recycled back into the soluble coffee extract. The fines are typically removed by sifting out the frozen fine material. No soluble coffee is therefore wasted.

[0006] The energy cost of such a conventional freeze-drying process is considerable. The energy costs include the energy consumed in initially cooling the extract, as well as the process- steps performed in a cold room, up to and including the freeze-drying steps. It would be desirable, particularly in a present period of increasing energy costs, to be able to reduce the energy consumption of the process.

[0007] Various previous attempts have been made to provide alternative freeze-drying processes.

[0008] WO2021005300 relates to relates to a lyophilized coffee having improved properties. This involves the production of coffee beads having a size of less than 30 microns by immersing a coffee extract in a cryogenic fluid. This serves to dissolve gas into the extract and to freeze and form the beads. The energy costs associated with this process will be significantly increased compared to a conventional process in view of the pressures and equipment required. FR3098090 provides a similar disclosure.

[0009] EP2305372 relates to a device and method for pelletizing or granulating a liquid or paste-like material. It involves a flow of liquid coolant through channels of the device.

[0010] WO2021180584 relates to a process for making a freeze-dried soluble beverage powder, the process comprising the steps; a. providing a liquid aqueous beverage composition having a total solids content between 5 and 65%; b. forming a layer of the liquid aqueous beverage composition between and in contact with two parallel flat surfaces, the surfaces being separated by a gap of from 0.1 to 10 mm; c. cooling the liquid aqueous beverage composition layer to below -25 °C to form a frozen beverage composition; and d. drying the frozen beverage composition.

[0011] WO2014207555 relates to a method for forming a coffee article for preparing a coffee beverage, the method comprising: providing a liquid coffee-extract; foaming and cooling the liquid coffee-extract to obtain a shape-retaining coffee-extract mousse, and shaping and freeze-drying the mousse to obtain a coffee article. Shaping may be performed with a drop roller which uses two complementary rollers each having matching indentations. The primary product of WO2014207555 is intended to be sufficient to prepare a coffee beverage by dissolution of a single coffee article, although it is also contemplated to use 1 to 3 for a beverage. The broad envisioned mass of each article disclosed is 0.3 to 5g, where a typical coffee requires 1 to 1 .5g. The examples are towards the 1 to 1 .5g region with one example being an oval article having a 30mm length, 13mm width and 5mm depth. In view of the size of the coffee articles they cannot be produced using conventional equipment, such as a freeze-drying bed. DE1906924 provides a method for changing the surface colour of a freeze-dried coffee product. Droplets (3mm diameter) of coffee extract are frozen to approximately minus 40°C, and then scraped onto a heat-emitting surface at a temperature of about -10°C for a few seconds. The contact causes the frozen droplets to darken. The frozen droplets are then fully frozen again and subjected to freeze-drying.

[0012] GB2496265 discloses a conventional freeze-dried coffee process for making a product which contains fine roast and ground coffee material. There is no contemplated annealing step.

[0013] Accordingly, the inventors sought to provide an improved method of producing a freeze-dried coffee product with a lower energy cost of production, and also to provide a new freeze-dried coffee product, or at least to tackle problems associated therewith in the prior art, or provide a commercially viable alternative thereto.

[0014] After devising their initial approach, the inventors separately discovered US6428833 which describes a similar process for obtaining a freeze-dried coffee extract in pellet form. This process shares a number of the advantages of the inventors’ approach but was also associated with a number of deficiencies which the inventors then sought to address.

[0015] In more detail, US6428833 describes a process in which coffee extract with a 35 to 45wt% solids content is foamed to a foam weight of 450 to 750 g / l and then dropped onto a cooled belt for the formation of pellets. The pellets are frozen on the belt to temperatures below minus 30eC and then freeze-dried. The product is preferably dropped onto the cooled belt in quantities such that, after freezing, pellets with a diameter of 4 to 7 mm, preferably approximately 6 mm, and with a height of 2.5 to 3.5 mm, preferably 3 mm are obtained.

[0016] The US6428833 method has a number of advantages over conventional freeze-drying processes. Clearly, the process avoids the formation of fines and avoids the need for a grinding step. The pellets dropped onto the cooled belt can be frozen to temperatures between -30 and -40eC within 2 to 3 minutes. In comparison with conventional processes, an approximately 10-fold saving in time is consequently achieved in this stage. Since the product does not have to be comminuted, and therefore no frictional heat is generated, it is sufficient to freeze the pellets at -30 to -40eC. Energy is therefore also saved in this stage. Overall, therefore, this method provides considerable energy savings.

[0017] US6428833 provides comparative examples comparing the benefits of the process over a conventional freeze-drying approach. These look at three different qualities of coffee A-C. In each instance the new pellets are formed in only a few minutes. They are cooled to a warmer temperature than is conventional and there are no fines produced. In this way the product is produced with a much lower energy cost.

[0018] US6428833 is aware of concerns relating to the colour of the product obtained. It discusses how the colour of the product can be controlled by having a staged vacuum drying time. Firstly an initial drying time to form a shell and a controlled pressure profile. This is said to give “an attractive appearance” and if the pressure is too low (below 0.8mbar) then “the pellets acquire a light or mottled appearance”. The inventors understand that such drying conditions cause colour darkening via slightly collapsing the coffee. Collapse is, however, not desired since it results in the loss of a consistent internal structure and thereby could reduce dissolution rate in the final product

[0019] When the inventors reproduced the method of US6428833 using a modern drying profile, however, they found that the product appearance was overly light. Rather than a conventional dark coffee colour, the pellets were light, creamy or beige in colour. This did not meet with consumer expectations. Furthermore, the disclosed drying process at higher pressures (less reduced) gives rise to a significant loss of aroma. Accordingly, it is an object of the present invention to provide a pellet product with the associated energy cost benefits, but which has a suitable colour and aroma profile. It is therefore a particular object to achieve this product without requiring a lengthy drying step of the pellets and without requiring the changes to a conventional freeze-drying apparatus outlined in US6428833.

[0020] According to a first aspect there is provided a freeze-dried coffee article having a mass of 0.10g or less, a density of from 0.20 to 0.8 g / cm3, a colour of less than 35 La, and a substantially flat base having an area of from 1 mm2to 50mm2, wherein the article is symmetric about at least one plane of symmetry and / or axis of rotation.

[0021] The present disclosure will now be described further. In the following passages different aspects / embodiments of the disclosure are defined in more detail. Each aspect / embodiment so defined may be combined with any other aspect / embodiment or aspects / embodiments unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous. It is intended that the features disclosed in relation to the product may be combined with those disclosed in relation to the method and vice versa. The present inventors investigated the primary energy costs of the freeze-drying process while seeking to provide a way of reducing the energy costs. The energy costs can be divided into those steps performed before the cold room, and those performed in the cold room. The steps before the cold room include pre-cooling, foaming and the further cooling to the temperatures where the extract is loaded onto a tray or conveyor belt. These account for roughly one third of the energy costs.

[0022] They have found that, of the approximately two thirds of energy costs in the cold room, the primary energy costs of a typical process are as follows (rounded percentages): cold room fans (-30%), cold room product load (-25%), grinding and sifting (-15%), cold room wall load (-5%), freezing belt fans (-5%), and a remainder of -10% for pumps, motors, lights etc.

[0023] As can be seen, there are lots of different energy costs in the process and it is not straightforward to arrive at a solution which reduces the costs. Nonetheless, the inventors have sought to provide a method which provides a freeze-dried product which addresses the key energy demands in this process. An important secondary consideration was also the capital expenditure associated with new equipment required to make a new product or process. It would be especially desirable if the product could be made using the existing equipment used to produce conventional freeze-dried coffee powders, in-so-far as possible, while still reducing energy consumption per unit weight of product.

[0024] In reproducing a method similar to that of US6428833, the inventors were able to produce a product addressing many of these issues. However, they found that the product appearance was unduly light in colour and consumer acceptance was low. This was the case when attempting to reproduce the vacuum drying conditions at elevated pressure (which are otherwise undesirable as discussed above due to the loss of aroma and poor industrial scalability), but especially also the case when using a conventional freeze-dryer under conventional conditions (i.e. suitable for freeze-dried coffee powders). The use of a conventional freeze-dryer was especially desirable, since this would reduce the cost of establishing the system and avoid undue drying times.

[0025] The inventors have now found that the colour of the article can be controlled through an annealing step performed during the freezing of the coffee articles. In this annealing step, the coffee articles remain within a temperature range of from -15 to -30eC for at least 20 minutes, preferably within a temperature range of from -18 to -28eC for at least 20 minutes. This is completely different from the teaching of US6428833, which aims to freeze in only a few minutes. Without wishing to be bound by theory, it is believed that the colour of the freeze-dried product is determined by its surface structure and, specifically in this case, the surface pore configuration. It is well known in the art that the colour of freeze-dried coffee can be changed by foaming the coffee extract before drying. An increased number of larger surface pores gives rise to a darker coloured product via a light scattering phenomenon. It is generally understood that the surface of conventional freeze-dried granules are dominated by pores derived from gas bubbles and this is why changing the foam structure is generally used to achieve darker powders.

[0026] In contrast, however, the larger unground articles (i.e. directly formed by deposition) obtained by the present method have a smoother outer surface which has fewer exposed bubble pores. This means that the light scattering is less effective and the product appears lighter. The inventors have now found that they can affect the surface appearance by controlling the ice-crystal surface pores on the freeze-dried coffee. Whereas ice pores are generally smaller than the gas bubbles in the product and therefore less involved in the light scattering, the inventors have found that a slow cooling or annealing step can help the ice crystals grow and mature such that there is a meaningful effect on the colour at the surface. Without wishing to be bound by theory, it is considered that this is especially true in high concentration systems where less water is present to become ice.

[0027] The inventors have found that annealing the ice in standard format granules (i.e. fragmented frozen coffee sheets) has a more limited colour impact - unlike the smooth outer surface of the larger unground articles of the invention, the bubbles outweigh the effect of ice growth since there is less ice present and plenty of bubbles. In addition, because in the invention the ice crystals form after the article is deposited, their growth is able to penetrate the surface and create a new structure, contributing to the desirable surface light scattering and darker colour. This was a surprising finding, namely that the bubble size has a reduced effect and the crystal size has a significantly increased effect on colour in the deposited format compared to for conventional granules. The benefits of the invention are particularly observed when forming a product from a higher-solids concentrate (i.e. less ice present) which is desirable to reduce energy costs.

[0028] It is known that slow-cooling around the freezing point of a coffee extract can help the formation of larger crystals and this is discussed at length in EP3448166. As explained therein, it is critical that for a four degree Celsius window, extending from 1eC above the freezing point to 3eC below the freezing point, the freezing rate is very slow. This window preferably takes at least 20 minutes and, thereafter, the Patent teaches that the cooling can be much faster down to a suitable freeze-drying start temperature. In EP3448166 this slow cooling is performed to provide a product with a reduced internal connectivity and hence produce a foaming product. This is very different to the present case, where the slow cooling is performed to change the product colour (and in a different target temperature range).

[0029] The inventors have now found that the surface ice-crystal structure, and hence the final product colour, can be best controlled by having a holding step performed on the already- frozen product. The holding temperature is within a temperature window colder than that taught in EP3448166 and it is surprising that this is key to providing the desired appearance. The inventors have found that the associated colour benefit is also observed when annealing in the production of a conventional freeze-dried powder, but that the benefits are especially pronounced in the product format described herein (having an otherwise smooth outer surface). In particular, performing the cold-annealing step allows the provision of a product that is darker than achievable in US6428833 and, moreover, it can still be achieved with the desirable dark colour using a conventional freeze-drying system with a substantially constant low pressure, avoiding the need for new equipment or a change in procedure. Furthermore, there is an improved aroma content (less loss) compared to drying under the conditions required in US6428833.

[0030] The cold holding step which gives rise to the desirable darker colour may be a holding step, or may be a slow cooling performed within the temperature window. The duration of the step is at least 20 minutes, as discussed below, and it is for this time that the product is held within the temperature range of -15 to -30eC, preferably -18 to -28eC. For the avoidance of doubt, during this holding time the product is preferably not under pressure or under vacuum, since this holding step is performed before the lyophilisation begins. Rather, the holding step is preferably at atmospheric pressure. Preferred holding steps are 20 minutes to 5 hours, preferably 30 to 180 minutes, more preferably 60 to 120 minutes, at a temperature of -18 to -30eC, preferably -20 to -25eC. A static holding temperature is preferred for process simplicity. Preferably there is only one holding step, rather than repeated cycling between temperatures.

[0031] After this low temperature annealing step is completed, the product may be immediately subjected to the freeze-drying step or, if necessary, it may be frozen to a colder temperature before this begins, such as a temperature in the range of -30eC to -50eC. Freeze-drying is performed using well known conventional techniques. Accordingly, in some embodiments the freeze-drying commences at the annealing temperature and in other embodiments the freeze-drying commences after further freezing.

[0032] In some embodiments the frozen coffee articles may be fast frozen at the point of production, such as down to -30eC to -50eC, preferably -35eC to -45eC, and then warmed for the cold annealing step to be performed.

[0033] The inventors have now found that this approach allows them to produce a novel product which is a freeze-dried coffee article having a mass of 0.10g or less, a colour of less than 35 La, a density of from 0.20 to 0.45 g / cm3and a substantially flat base having an area of from 1 mm2to 50mm2, wherein the article is symmetric about at least one plane of symmetry and / or axis of rotation. In comparison, a conventional freeze-dried coffee has a particle size distribution of about 1 to 4mm and the particles are irregular in shape.

[0034] The freeze-dried coffee article has a mass of 0.1 g or less, preferably less than 0.095g, preferably 0.01 to 0.1 g, preferably 0.02 to 0.09g and most preferably 0.025 to 0.075g. These masses are optimal for providing a product which matches the use of a conventional freeze- dried product (i.e. one spoonful in a beverage) and is also compatible with the process as discussed below. Where the article is too large, there may be structural issues on drying, and where the article is too small, there may be processing issues (such as the article being entrained in gas-flows).

[0035] The freeze-dried coffee article has a colour of less than 35 La, preferably 30 to 15 La, more preferably 18 to 25 La. “La” colour measurement is a well-known approach to qualify the colour of a coffee product. Lower numbers are associated with a darker colour. “La” colour measurements can be performed using a Dr Lange LK 100 unit (Hach-Lange GmbH). The standard operating procedure of the unit involves spreading a layer of the sample flat in a standard sample holder before measurement.

[0036] The freeze-dried coffee article preferably has density of from 0.20 to 0.65 g / cm3, preferably from 0.30 to 0.45 g / cm3. Preferably the article has a density of from 0.30 to 0.36 g / cm3. These densities serve to characterise the internal porosity of the coffee articles. A ground coffee powder typically has a density of around 1 .48 g / cm3, so the above low densities help to describe the internal pore structure which is a consequence of pre-foaming and ice voids resulting from freeze-drying. As discussed below, this structure is important for the dissolution of the final product and also for compatibility with the forming and drying steps. The freeze-dried coffee article has a substantially flat base having an area of from 1 mm2to 50mm2. The flat base is a function of the manufacturing process as described herein and provides the surface on which the article rests on the freezing belt. As a consequence, although the base will have a potentially uneven porous structure as described below, it will nonetheless provide a flat surface on which the article can rest. The area of the base is directly linked to the size of the article, such that heavier articles will generally have a larger base. A preferred area is from 4 to 20mm2.

[0037] The freeze-dried coffee article is symmetric about at least one plane of symmetry and / or axis of rotation. By way of example, a dome-shaped article would have both an axis of rotational symmetry around an central axis orthogonal to the base of the article and planes of symmetry also orthogonal to the base of the article. A hemispherical prism would have both an axis of rotational symmetry around a central axis orthogonal to the base of the article and two planes of symmetry orthogonal to the base of the article, bisecting the length and width of the article. The presence of these elements of symmetry are a consequence of the uniform manufacturing process and serve to clearly distinguish over conventional freeze- dried coffee processes where the splintering of the frozen slab produces an irregular particle form.

[0038] Preferably the coffee article is dome-shaped. By “dome-shaped”, it is meant that the product has a circular or oval base (preferably circular) and the body of the product forms a substantially hemispherical shape when sitting on said base. Depending on the ratio of the height of the dome to the radius of the base, the article may be a perfect hemisphere or more closely resemble a lentil or split pea. The base is typically flat since it is formed when viscous coffee extract is placed on a cooling surface, such as the top of a freezing belt. When a product does not have a circular base, the radius is an average of the longest and shortest radii.

[0039] The dome-shaped freeze-dried coffee article has a base radius of 0.5 to 4mm. Preferably the article has a base radius of from 1 to 3mm and more preferably from 1 .5 to 2.5mm. Above a radius of 4mm the solubility of the particle was significantly reduced. Below a radius of 0.5mm the size is too small to be usefully scaled - there is a capacity challenge with filling freezing belts and, in addition, there are drying challenges because the fine particles can be entrained with air flows in the drier.

[0040] Preferably the dome-shaped article has a ratio of height to the base radius of from 1 :4 to 5:4, preferably 1 :3 to 1 :1. This ratio helps to describe the appearance of the article and the extent to which it is domed. The closer the ratio is to 1 :1 the more hemispherical the product. A more hemispherical product is desirable but not critical. It is desired that the ratio is at least 1 :4 so that the product retains a visibly domed upper surface. The ratio also helps to define a surface area to volume ratio which is a factor in the freeze-drying process.

[0041] According to another embodiment, the article has an axis and a substantially constant crosssection orthogonal to said axis a perimeter of said cross-section consisting of an arc and a chord, the chord forming the flat base. This is the form that would be adopted when a cylinder of material is allowed to rest on a surface and the material sags to form a flat base surface. This is the form which is prepared in accordance with the subsequently described processes involving extrusion and on-belt cutting. In these embodiments it is preferred that a ratio of the length of the coffee article to the height is greater than 1 :1 , preferably greater than 4:1 and generally between 5:1 and 10:1. That is, the article is more “coin-shaped” than “column-shaped”.

[0042] Preferably the arc is elliptical or circular. Preferably the article has a ratio of height to the chord of from 1 :4 to 5:4, preferably 1 :3 to 1 :1. It is desired that the ratio is at least 1 :4 so that the product retains a visibly curved upper surface. The ratio also helps to define a surface area to volume ratio which is a factor in the freeze-drying process.

[0043] Preferably the freeze-dried coffee article consists of coffee solids and preferably only solids from the original coffee extract. However, it is also possible that the article comprises one or more further ingredients homogeneously distributed therein. Further ingredients include creamers, Whiteners, sugar and sweeteners.

[0044] It is also preferred that the articles comprise up to 10wt% of roast and ground coffee additive, preferably from 1 to 8wt% and most preferably 3 to 5wt%. These would contribute to the coffee solids in the final product. A preferred roast and ground coffee additive is a microground coffee which is well known in the art. Examples of products with microground coffee include Millicano™. A general definition of a microground roasted coffee is one having a D50 of less than 40 pm and a D90 of less than 80 pm. The presence of such an additive improves the flavour and aroma and gives a higher perceived product quality.

[0045] Preferably the article has a substantially flat base surface and an upper surface, the base surface having a reduced gloss and / or increased porosity compared to the upper surface. In practice, this is a consequence of the flat surface resting on a freezing belt after it is formed. The base surface is directly comparable with the equivalent surface of a freeze-dried coffee, formed against the freezing belt. The upper surface is exposed to cooling air-flow and this provides its increased surface shine and reduced porosity. The article preferably consists of the base surface and the upper surface, such that the upper surface describes everything on the article which was not in contact with the freezing belt. The upper surface will always be greater than 50% of the article and the base will always be less than 50% of the article.

[0046] Due to the air-flow impinging on the upper surface during production it is significantly less porous and more shiny than the base. In particular, the upper surface has significantly fewer pores with diameter of 5 to 18pm or above. In contrast, the base surface is not shiny and has a prevalence of pores of 20 to 50pm.

[0047] Without wishing to be bound by theory, it is considered that the ratio of the base radius to height reflects on the solubility of the final product. The base is more porous and this helps solubility, whereas the surface is smoother - albeit that the slow-cooling approach does disrupt this surface to an extent. When moving towards larger articles as described in WO2014207555, there is a reduced amount of base compared to the dome surface and the associated volume. Thus, the claimed articles are a surprising optimised balance which dissolves well, like a conventional freeze-dried powder.

[0048] These freeze-dried coffee articles are much smaller than those of WO2014207555. Whereas the product of WO2014207555 is intended to be sufficient to produce a whole beverage, the present product is intended to still be spooned into a cup like a conventional freeze-dried coffee product.

[0049] The inventors considered the teaching of WO2014207555 but found that its embodiments were not suitable to meet the present objectives. In particular, because the articles were so large, freeze-drying in conventional freeze-drying equipment led to a melting of the structure internally before drying could be completed. That is, the heat used to sublime out the water struggled to penetrate the larger articles, such that additional heat was required and this led to melted portions which then struggled to dissolve. The only way around this was to use colder initial freezing temperatures and specially adapted freeze-drying equipment able to provide suitable drying conditions. This meant that there was an increased energy and CAPEX cost.

[0050] A clear example of this may be seen in the trays used for the freeze-drying step. When performing the freeze-drying step of heating at a reduced pressure to sublime away the water, a conventional frozen, fragmented coffee powder is loaded into metal trays which may be provided with regular metal ridges or baffles across the tray. The frozen coffee is loaded to provide a packed bed, which assists with heating of the granules, and where any ridges or baffles assist in the conductive heat transfer. For the larger articles of WO2014207555, these would not fit into these standard cooling trays and could not be formed into a packed bed. If they were placed in such trays then they would experience significant localised heating at contact points could lead to localised melting and poor solubility. As a consequence it would be necessary to design specialist cooling trays and determine specific, slower heating conditions to avoid these detrimental consequences.

[0051] There is no suggestion in WO2014207555 that the process could be used to make such small articles as described herein. The present inventors have found that the balance of weight, density, shape and size is critical to the production of the final product. In particular, the product can be shaped at normal cooling conditions using conventional equipment (e.g. in a scraped surface heat-exchanger and not requiring temperatures below -12°C) and retains its shape for cooling. The articles of the invention can also be loaded into existing trays to form packed beds for efficient drying. This concept of shape-retaining is different from that in WO2014207555, where complex surface structure was desired. Rather, this combination of features in a product so small results in a surface tension which keeps the formed article regular. For example, a hemispherical deposited amount of viscous extract may sag and become shaped like a lentil, but the combination of weight, density, shape and size means that it does not spread or merge with adjacent articles and it retains a symmetrical structure. This means that warmer temperatures can be used than for conventional freeze-drying, reducing the associated energy cost.

[0052] In addition, the final product when freeze-dried is equivalent to a conventional freeze-dried coffee powder in terms of solubility. This means that it dissolves substantially as quickly as a conventional freeze-dried coffee powder. This is critical since a significantly decreased solubility could lead to a product which does not meet with consumer approval.

[0053] According to a further aspect there is provided a composition comprising a plurality of the coffee articles described herein. Preferably the composition is provided in a multi-serving jar, such that in use a consumer spoons out the composition into their coffee mug. Alternatively, the composition can be provided in a stick-pack, sachet or beverage-machine capsule (including pods, pads and the like).

[0054] The coffee articles may all be produced having a monomodal size distribution of the base radii of the coffee articles. That is, if they are all produced using the same mould or depositor, or cut in the same way, then they would all look substantially identical and will be uniform in appearance. This is advantageous in some applications, such as where the solubility is desirably the same for each article. When considering a monomodal or multimodal distribution, it is expected that each peak will be narrow, such that the variation in sizes for each peak is less than 10%, preferably less than 5%, more preferably less than 2% (highest size minus lowest size as a percentage of peak value).

[0055] However, in some other instances it is desirable to have a range of different sizes, such as a range of base radii for dome-shaped articles. Equally, different cut lengths can be achieved in other applications. This may make the shapes more closely resemble a conventional freeze-dried coffee powder, where the sizes are all random as a result of grinding. In practical manufacturing terms, it will be difficult to produce the articles with a true distribution of sizes. Using a range of different depositors, moulds or cut-lengths it would be possible to obtain a set number of different sizes, such as at least 2, preferably at least 4 and most preferably 5 to 10 different sizes. A composition formed in this way would have a non- continuous multimodal distribution.

[0056] Preferably the composition has a bulk density of from 150 to 400g / L, preferably 210 to 250g / L. This takes into account both the internal porosity of the articles and also their packing density.

[0057] The composition may further comprise additional ingredients such as a creamer or whitener, or sugar or a sweetener. These further ingredients may be provided as a powder and the composition therefore comprises a dry admixture of the powder and the articles.

[0058] Alternatively, the further ingredients may also be provided in an equivalent freeze-dried article form. That is, preferably the coffee composition comprises at least 10wt% of a conventional freeze-dried or spray-dried coffee powder, preferably freeze-dried coffee powder and preferably in an amount of 15 to 80wt%, more preferably 20 to 50wt%. The presence of conventional freeze-dried coffee can help to drive consumer acceptance of the new product shape and form.

[0059] According to a further aspect there is provided a method for the manufacture of a plurality of freeze-dried soluble coffee articles, the method comprising:

[0060] (i) providing an aqueous coffee extract comprising at least 40wt% soluble coffee solids;

[0061] (ii) foaming and cooling the aqueous coffee extract to form a foamed viscous coffee extract; (iii) depositing the foamed, viscous coffee extract onto a surface to form a plurality of individual coffee articles;

[0062] (iv) freezing the plurality of individual coffee articles to form a plurality of frozen coffee articles; and

[0063] (v) subliming water from the plurality of frozen coffee articles under a pressure of less than 0.7mbar, preferably 0.1 to 0.5mbar, to form a plurality of freeze-dried soluble coffee articles, each having a mass of 0.10g or less and a colour of less than 35 La, wherein, in step (iv) the freezing of the individual coffee articles includes a low temperature annealing step whereby the coffee articles remain within a temperature range of from -15 to -35eC, preferably -20 to -30eC, for at least 20 minutes.

[0064] The method is for the production of a plurality of freeze-dried soluble coffee articles and is suitable for producing the coffee articles discussed above. Preferably the method is for the manufacture of the coffee articles described herein.

[0065] The method has a number of significant advantages. Since the freeze-dried articles are produced individually, rather than by fragmenting a slab, there is no need for a grinding step. This obviously leads to a saving on the grinding energy, but more critically it avoids the need for a grinder in the cold room space. This means that the cold room can be smaller and / or the energy requirement to keep it cold can be reduced.

[0066] In addition, since there is no grinding step, there are no fines produced. In a conventional process the level of recycled fines can be up to 30wt% of the material so there is a significant energy cost associated with recovering it and reintroducing it into the process (melting, solubilising and recooling). There is therefore no need to recycle the fines back into the coffee extract in the present method. As a consequence, the process complexity is significantly reduced. More critically it avoids the need for fines-sifting in the cold room space. This means that the cold room can be smaller and / or the energy requirement to keep it cold can be reduced.

[0067] It should be appreciated that both grinding and sifting require large multi-floor space in the cold room, so the avoidance of these requirements gives rise to a significant space reduction. Furthermore, in principle it is also possible as a consequence of the disclosed method to replace the cold room itself using the present process and to instead use an enclosed freezing belt to freeze the viscous coffee extract and to take it to the drier. Surprisingly, the inventors have found that these cumulative advantages can significantly reduce the energy costs of the process. This arises from a -15% energy cost reduction by removing the grinding and sifting machinery (and the refrigeration it requires), a -10% reduction by eliminating the fines recycling and a -10% reduction associated with the warmer temperatures which the process affords (-35°C vs -50°C). Still further energy savings can then be realised by the reduction in size required for the cold room itself, or replacing it with an enclosed freezing belt. There are also safety improvements when the cold room cannot be entered by operators and there is no need to do so.

[0068] In addition, since the coffee articles are so small, each having a weight of 0.10g or less, it is possible to use entirely conventional freeze-drying equipment. When using such equipment the articles are not prone to melting or the formation of slow-to-dissolve internal structures. Thus, at a third of the energy cost of the process it is still possible to produce a desirable freeze-dried coffee product that has the same desirable flavour properties and good dissolution performance. This is about a 15% energy saving over the whole bean to product process (i.e. including roasting, extraction, evaporation and drying).

[0069] The method comprises a step (i) of providing an aqueous coffee extract comprising greater than 40wt% soluble coffee solids. The higher the solids content the less water needs to be removed during freeze-drying. However, at very high solids there are associated difficulties with the preceding foaming and cooling steps. Preferably the aqueous coffee extract has 45 to 65wt% soluble coffee solids, preferably 48 to 52wt% soluble coffee solids.

[0070] The method comprises a step (ii) of foaming and cooling the aqueous coffee extract to form a foamed coffee extract. Coffee foaming processes are well known in the art and any suitable process may be used. This includes gas injection into the extract and also systems which simultaneously foam and produce ice (e.g. scraped surface heat exchanger). The intention of the foaming step is to affect the density of the coffee extract and hence the bubble structure of the finished product. One approach to foaming is to introduce a gas under pressure into the pumped coffee extract. The pressurised coffee extract can then be depressurised with associated foaming for the following steps. A suitable pressure for the extract into which the gas is added is from 10 to 400 Bar, preferably 20 to 150 Bar and most preferably 30 to 50 Bar. Suitable gases for addition include nitrogen and carbon dioxide. Preferably the foamed coffee extract has a density of from 400 to 900g / L, preferably 650 to 750g / L. The cooling of the foamed coffee extract may be in a scraped surface heat exchanger to form a viscous coffee extract. A scraped surface heat exchanger is commonplace in the art, such as those made by SPX Flow. These help to freeze the coffee extract on a cooled outer surface while a scraper displaces the frozen material. Preferably the foamed coffee extract is cooled in step (ii) to a temperature of 0 to -16°C, preferably -6 to -12°C, and most preferably -6 to -10°C.

[0071] The method further comprises a step (iii) of depositing the viscous coffee extract onto a surface to form a plurality of individual coffee articles. There are many ways in which this could be achieved as discussed below. Preferably step iii) comprises either a) individually depositing amounts of the viscous coffee extract onto a freezing belt, preferably using an extruder or rotary depositor; or b) extruding the viscous coffee extract onto the freezing belt and cutting it in situ to form the plurality of frozen coffee articles. In general alternative a) is more preferred.

[0072] Most preferably the method uses a rotary depositor. These are well known in the art. These are not expensive and are capable of producing a large number of articles quickly with a consistent structure and separately located on a freezing belt. Accordingly, the use of a rotary depositor does not significantly increase the CAPEX costs. A rotary depositor is a large drum having a plurality of cavities through which the viscous coffee extract is deposited onto the freezing belt. The drum rolls to deposit individual portions of the viscous coffee extract onto a freezing belt. This sort of rotary depositor differs from drop rollers, since the product is formed on the freezing belt, rather than falling from between two rollers. There is a flat based formed. This is advantageous because there is no need for further processing, it produces uniform granules and cleaning is straight-forward. This process is ideally suited for forming the preferred dome-shaped coffee articles.

[0073] Other techniques for performing step (iii) include: granule formation using an extruder and associated cutter; granule formation using an extruder for extruding a rope of viscous coffee extract onto a freezing belt having an associated cutter; a nozzle depositor associated with a freezing belt, optionally associated with moulds on the freezing belt. The use of some of these methods, in particular those using a cutter, would not be expected to provide a domed coffee article.

[0074] In embodiments of step (iii) which comprise individually depositing amounts of the viscous coffee extract onto a freezing belt using an extruder and a cutter, where cut pieces of the viscous coffee extract fall onto the freezing belt, preferably the speed of the freezing belt is configured such that a majority of the cut pieces contacting the freezing belt are not in contact with another cut piece. This process is ideally suited for forming the preferred articles having an axis and a substantially constant cross-section orthogonal to said axis a perimeter of said cross-section consisting of an arc and a chord, the chord forming the flat base, i.e. the cylinders with a flat side surface.

[0075] In comparison to a conventional freeze-dried process and certainly also in comparison to the method of WO2014207555, the initial freezing step performed on the freezing belt is very quick. Specifically, the freezing belts may be configured to freeze the articles in less than 120 seconds, preferably between 40 and 100 seconds, such as 60 to 80 seconds. In contrast, a conventional freeze-dried coffee process would achieve the equivalent freezing step in 6 to 10 minutes.

[0076] At the same time, the freezing belts used in the present process may be run at least twice as fast as in a conventional process, preferably 4 to 6 times faster. This allows for a high throughput, despite the lower freezing belt utilisation, since the individual coffee articles need to be kept separate from each other during deposition. The shape of the articles with the relatively larger base helps to keep the articles stably on the faster belt, despite the belt movement speed and the cooling fan-driven air. The density of the articles also helps them to maintain their uniform shape under these conditions.

[0077] The method comprises a step (iv) of freezing the plurality of individual coffee articles to form a plurality of frozen coffee articles. In the embodiments discussed above where the individual coffee articles are deposited directly onto a freezing belt, step (iv) starts immediately once the foamed viscous coffee extract is deposited. Preferably the freezing step is performed targeting a final frozen temperature of from -32 to -50C, preferably -32 to - 37°C, preferably about -35°C.

[0078] In step (iv) the freezing of the individual coffee articles includes a low temperature annealing step whereby the coffee articles remain within a temperature range of from -15 to -35eC, preferably -18 to -30eC for at least 20 minutes. Preferably the coffee articles remain within a temperature range of from -20 to -25eC for at least 20 minutes. More preferably this step is performed for at least 25 minutes, more preferably at least 30 minutes and typically for at least 90 minutes. Overly long times are less commercially desirable, although the product may still be desirably darkened. A maximum time is preferably less than 5 hours, preferably less than 3 hours. The annealing step may be performed on a freezing belt or the articles may be collected from the belt and annealing can take place in a cold room. After this low temperature annealing step is completed, the product may be immediately subjected to the freeze-drying step or, if necessary, it may be frozen to a colder temperature before this begins, such as a temperature in the range of -30eC to -50eC. Freeze-drying is performed using well known conventional techniques. Accordingly, in some embodiments the freeze-drying commences at the annealing temperature and in other embodiments the freeze-drying commences after further freezing.

[0079] In some embodiments the frozen coffee articles may be fast frozen at the point of production, such as down to -30eC to -50eC, preferably -35eC to -45eC, and then warmed for the cold annealing step to be performed. Preferably in this embodiment the annealing is at least 5eC and more preferably at least 10eC warmer than the initial freezing step. This ensures complete freezing of the articles and then consistent annealing and ice-crystal growth. Preferably there is a single annealing step during the freezing step. That is, there is a single step in which the frozen coffee body is allowed to warm before having the water sublimed away, rather than having the temperature of the frozen coffee body repeatedly cycled.

[0080] During the annealing step the frozen coffee articles typically remain on the trays or on a belt. The frozen coffee bodies are preferably not subjected to any additional agitation or coating steps. In this way the surface of the final tablet consists of coffee from the coffee extract.

[0081] In other embodiments the annealing step is performed as part of the continuous (or stepwise) cooling profile.

[0082] The method comprises a step (v) of subliming water from the plurality of frozen coffee articles under a pressure of less than 0.75mbar, preferably 0.1 to 0.6mbar and most preferably about 0.5mbar, to form a plurality of freeze-dried soluble coffee articles, each having a mass of less than 0.10g and a colour of less than 35 La. The subliming is preferably a conventional freeze-drying of the plurality of frozen coffee articles to form a plurality of freeze-dried soluble coffee articles. Freeze-drying process, also known as lyophilisation, are well known in the art.

[0083] Preferably step (v) of subliming water is performed at an initial temperature of from -32 to - 37°C, preferably about -35°C. In some embodiments the freeze-drying can commence at the annealing temperature as this concludes. The initial temperature is the temperature usual deposited for freeze-drying processes, but it will be appreciated that the temperature can rise (become less cold) during the drying process. While it may be generally disclosed in patent applications that such temperatures may be employed, this is almost never the case in practice. Colder temperatures are generally employed to ensure that the whole slab freezes before the grinding step. On the other hand, since the present method dispenses with the need for grinding, and since the uniform nature before freeze-drying of the product allows better targeting of the freeze-drying conditions, the method of the present invention can be operated at a warmer temperature leading to significant energy savings.

[0084] Preferably the method does not involve the recycling of fines material formed after or during step (iii) back into the process before step (iii).

[0085] Preferably the plurality of freeze-dried soluble coffee articles are substantially identically shaped. Preferably a size distribution of the coffee articles has a non-continuous distribution and, preferably has a multimodal distribution.

[0086] According to a further aspect there is provided a method which comprises dissolving the coffee composition as described herein in a liquid, preferably water. Preferably the water will be hot water, such as having a temperature of from 80 to 95°C, preferably about 85°C. The water may be provided in the form of milk, such that the dissolution of the articles produces a latte-style coffee beverage.

[0087] The invention will now be described further in the following figures. In which:

[0088] Figure 1 shows cross-sectional views through a dome-shaped coffee article obtained by the method described herein.

[0089] Figure 2 shows a cross-sectional view through a cylinder with a flat-side coffee article obtained by the method described herein.

[0090] Figure 3 shows a photo of conventional freeze-dried coffee granules.

[0091] Figure 4 shows a photo of the top surface of a coffee article obtained by the method described herein. The radius is approximately 3mm.

[0092] Figure 5 shows a photo of the porous internal structure of a coffee article obtained by the method described herein. Figures 6A and 6B a micrographs showing the porous base and less porous, shiny dome surface, respectively, of a coffee article obtained by the method described herein.

[0093] Figure 7 shows a flow-chart comparing a conventional process for producing a freeze-dried coffee and the method described herein.

[0094] Figure 8 shows a temperature curve showing the cooling of the frozen coffee articles and an annealing step.

[0095] Figure 1 shows a cross-section schematic through two coffee articles 5. This has a domed upper surface 10 and a base 15. The height and radius are shown. The first article 5 has a substantially hemispherical shape, whereas the second article 5 is more lentil-shaped.

[0096] Figure 2 shows a cross-section schematic through a coffee article 5. This has an upper surface 10 and a base 15. On the end cross-section, the upper surface 10 defines an arc and the base defines a chord. The height and radius are shown. The article 5 is shaped like a cylinder having a flattened side.

[0097] Figure 7 shows a flow-chart comparing a conventional process for producing a freeze-dried coffee and the method described herein. These have been presented together to highlight the same use of equipment and also to show the process steps that can now be avoided.

[0098] The methods firstly involve a step of providing an aqueous coffee extract 25. The coffee extract 25 comprises dissolved soluble coffee solids and may also comprise insoluble roast and ground coffee particles. In a conventional freeze-drying process, the aqueous coffee extract will typically have 35 to 45wt% soluble solids, whereas in the present method the aqueous coffee extract will typically have 45 to 55wt% soluble solids. That is, the process can be performed with higher than normal solids levels.

[0099] The aqueous coffee extract 25 is then subjected to a cooling step 30. The cooling step is performed to increase the viscosity of the aqueous coffee extract 25 and in advance of freezing. In a conventional freeze-drying process, the aqueous coffee extract will typically be cooled to a temperature range of -6 to -12°C and a similar temperature range is used in the present method. The cooled aqueous coffee extract 25 is then foamed in a foaming step 35. The target extract density will depend on the desired final product.

[0100] In a conventional freeze-drying process the foamed and cooled aqueous coffee extract 25 is then dispensed onto a freezing belt or filled into cooling trays in a dispensing step 40. In contrast, the foamed and cooled aqueous coffee extract 25 in the present method is passed to a shaping step 45 before the dispensing step. Preferably the shaping step 45 involves feeding the aqueous coffee extract into a roller mould which dispenses individual amounts of the extract onto a freezing belt in discrete coffee articles.

[0101] The dispensed coffee extract in each method is then subjected to a freezing step 50. Within this freezing step 50 there is an annealing performed with a holding of the product at about minus 25°C for several hours. In a conventional freeze-drying process, the dispensed coffee extract is typically frozen to around minus 50°C, whereas in the present method the dispensed coffee extract is typically frozen to around minus 35°C. That is, the process can be performed with higher-than-normal temperatures giving a significant saving.

[0102] In a conventional freeze-drying process the frozen coffee extract is then subjected to a grinding step 55 and a sifting step 60 which recovers fines material. The recovered fines material is melted / solubilised and returned into the initial aqueous coffee extract 25. These steps are no longer required in the method described herein.

[0103] In both processes the frozen coffee extract is then subjected to a lyophilisation drying step 65. As noted above, the present method permits this to be performed with a warmer starting material, saving energy costs. The final dry product 70 is then packaged for sale and distribution.

[0104] The invention will now be described further in relation to the following non-limiting examples. (comparative)

[0105] Providing an aqueous coffee extract comprising 48wt% soluble coffee solids;

[0106] Foaming the aqueous coffee extract to form a foamed coffee extract of density 700 g / L which is also cooled to a temperature of -6°C; Pre-freezing the foamed coffee extract in a scraped surface heat exchanger to form a viscous coffee extract at -10°C;

[0107] Manually depositing the viscous coffee extract onto a pre-cooled tray to form a plurality of individual dome-shaped coffee articles;

[0108] Freezing the coffee articles down to a temperature of -50°C; and

[0109] Freeze-drying the plurality of frozen coffee articles to form a plurality of freeze-dried soluble coffee articles of bulk density 230 g / L and mass of 0.1g.

[0110] Inspection of the dried coffee articles revealed a considerably broken-down internal structure, producing a dark, crumbly inner granule. Upon rehydration these coffee articles produced a cup with a dark spots of insoluble coffee and large bubbles on the surface (comparative)

[0111] Providing an aqueous coffee extract comprising 48wt% soluble coffee solids;

[0112] Foaming the aqueous coffee extract to form a foamed coffee extract of density 680 g / L which is also cooled to a temperature of -6.5°C;

[0113] Pre-freezing the foamed coffee extract in a scraped surface heat exchanger to form a viscous coffee extract at -9.5°C;

[0114] Manually depositing the viscous coffee extract onto a pre-cooled tray to form a plurality of individual dome-shaped coffee articles;

[0115] Freezing the coffee articles down to a temperature of -50°C; and

[0116] Freeze-drying the plurality of frozen coffee articles to form a plurality of freeze-dried soluble coffee articles of bulk density 220 g / L and mass of 0.05g.

[0117] The internal structure of these smaller granules was less broken down, leaving a much lighter brown colour similar to that of the outer surface. Upon rehydration these coffee articles produced a cup with a only a few dark spots of insoluble coffee and a larger number of small bubbles on the surface. (comparative)

[0118] Providing an aqueous coffee extract comprising 48wt% soluble coffee solids;

[0119] Foaming the aqueous coffee extract to form a foamed coffee extract of density 710 g / L which is also cooled to a temperature of -6.5°C;

[0120] Pre-freezing the foamed coffee extract in a scraped surface heat exchanger to form a viscous coffee extract at -10°C; Extruding the viscous coffee extract into 5mm wide strands onto a pre-cooled tray and then cutting these strands in a -50°C environment with a circular blade to form a plurality of individual cylindrical-shaped coffee articles;

[0121] Freezing the coffee articles down to a temperature of -50°C; and

[0122] Freeze-drying the plurality of frozen coffee articles to form a plurality of freeze-dried soluble coffee articles of bulk density 240 g / L and mass of 0.06g.

[0123] The internal structure of these granules showed low levels of meltback, producing a few dark areas but predominantly intact structure. Upon rehydration these coffee articles produced a cup with some dark spots of insoluble coffee and a couple of large bubbles on the surface.

[0124] Example #4 (inventive)

[0125] Example #1 was repeated with different annealing steps and the colour of the product was observed. In this example there was a rotary deposition system used, and foaming / cooling was to 700g / L at -7eC. This was then directly fed to the rotary depositor without additional cooling. The holding time was 2 hours. Product density was in the range 0.30 to 0.36 g / cm3

[0126] As can be seen, the annealing holding step is critical to ensuring a desirable darker coloured coffee product. By providing an example at the largest size, it is considered evident that it will also work for smaller articles. The smaller articles are preferred at least for consumer acceptance.

[0127] Further studies

[0128] Following the above Examples, the inventors performed further reports investigating the pore structure of the new product and its colour, and also checking the aroma. The project aims to directly form freeze-dried (FD) granules to eliminate the current FD grinding & sifting (G&S) process. By doing so, significant operational energy savings can be achieved which would directly help contribute to reduce emissions.

[0129] The best-fit technology was found to be rotary deposition. This selection was based upon energy savings (high), fines production (near zero), and scalability (industrially available).

[0130] Following initial feedback suggesting darker colours would be preferred, a method to darken drop colour using controlled freezing profile was developed. The conventional methods of adapting internal bubble structures was not found to be effective in the new format.

[0131] Structural Report

[0132] This report summarises porosimetry analyses which shed light into the internal pore structures of different drop format prototypes and a reference FD granule. From these, conclusions are inferred into the mechanism driving the increased aroma retention seen in the drops. Moreover, data is offered to explain the recently discovered method to darken drop colour through controlled freezing.

[0133] Mercury intrusion porosimetry was conducted on samples. In total, 5 samples were sent for analysis which give insights into both the aroma retention properties of the new format and the relationship between drop colour and porosity. An outline of the samples is given below.

[0134] For a fair comparison, all samples in the investigations were produced at the same time and with the same coffee extract. Note that this resulted in having two “dark drop” samples. The unrefined sample, unlike all the samples, were not sieved to obtain consistent size and shapes. It was found that generally the pore sizes in novel format dark drops were smaller than standard format FD. It is suggested in literature that this should lead to a reduction in retained aroma as the small pores increase localised vapour pressure during drying which, in turn, causes temperature increases and greater aroma evaporation. Therefore, it is surprising that the opposite result was seen in recent aroma analysis between these two samples.

[0135] It was found that there are differences in the internal pore structures as droplets move from light to dark colour (via changing freezing profile). Interestingly, the data suggests a correlation between drop darkness (gentle freezing profile) and reduced intrusion. It may be that closed pores could aid aroma retention.

[0136] Alternatively, the freezing profile could impact total measured intrusion through impacting the ability to hold gas. Gently freezing samples would lead to prolonged periods in the liquid and semi-liquid state. It is reasonable to assume that increased durations in these states would give greater opportunity for gas bubbles to be lost. This could also explain the apparent reduction in porosity in darker coloured samples.

[0137] The data also highlights differences between the samples’ internal structures. There appears to be a strong correlation between dark colour (gentle freezing) and increasing pore size, tending to a prominent peak at around 10 microns. Assuming the pores are the result of sublimated ice crystals, a reasonable explanation would be that the gentler freezing profiles give rise to increased ice crystal sizes. This was expected and desired when actively attempting to reduce freezing rate. These results therefore corroborate the theorised link between dark colour and increased internal pore size.

[0138] While as yet unproven, it is possible that the near monomodal internal pore structure can promote increased drying rates. The structure appears similar to that of a standard FD granule although the maximal intrusion was observed at slightly larger pore size: greatest peak at 10.2 microns in the very dark drops rather than 8.4 microns in the reference FD granule. Large ice crystals are believed to offer less resistance to escaping water vapour therefore this difference may lead to some drying benefit.

[0139] It was concluded that: The increased aroma retention in dark drops vs standard FD granules is not solely caused by increased pore size and a corresponding reduction in vapour pressure (and temperature) in drying.

[0140] • Results show a surprising increase in aroma retention in the novel dark drops.

[0141] • The (novel) combination of drop formation (e.g. rotary deposition), slow freezing and low-pressure drying is likely optimal to maximise aroma retention.

[0142] • Results clearly correlate increasing pore size with darker colour drops.

[0143] Aroma Report

[0144] Aroma is a critical quality factor for consumers. Conventionally, increasing aroma in FD instant can be achieved by changing the coffee (e.g. arabica content or extraction technology). However, changing the format could have an impact on the aroma retention, even when the same coffee and drying conditions are used. This report compares in-cup and over-cup headspace aroma of both current format FD and new-format rotary-deposited drops produced with the same coffee.

[0145] Concentrated coffee liquor was sourced. The extract was cooled and foamed to a temperature of -7 C and density of around 700 g / l in a scraped surface heat exchanger. Reference trays of product were taken and frozen in the -50C cold room. The same coffee was then fed to the pilot new-format rotary-depositor where it was deposited onto pre-cooled trays. Once deposited, the trays were transferred to cabinet freezers kept at -30C for colour darkening.

[0146] After several hours of being held at -30C, the droplets (still on trays) were moved to the cold room where they were removed from the trays via scraping. The droplets were loaded into conventional trays in preparation for drying. Meanwhile, the reference trays of frozen foamed coffee extract were grinded to form frozen granules. These were also then loaded into trays for drying. Both formats were dried in the same run under a standard fast drying cycle. After drying, both the drops and standard format FD were respectively packed into air-tight bags and sealed. The two packed bags had comparable head space. The samples underwent aroma analyses. These were aroma headspace in vial gas chromatography tests. This was done on both the powders and brews from the respective powders (made with 1 .5 g per 100 ml hot water) to simulate aroma before and after brewing the coffee.

[0147] For the dried powder, within the error bars, the low levels of aroma measured in the headspace above the powders meant that no significant difference was measured between the drops formed by rotary deposition and current format. Both powders did not undergo any subsequent processing to increase aroma.

[0148] For reconstituted brews there was a significant increase in measured aroma over the brew (in the headspace) in the new drop format from rotary deposition compared to the standard FD granules (70ng / mL, vs 47ng / mL). Unlike the analysis on dried powders, the difference was significant and beyond the uncertainty in the measurement technique. The new format was found to release 33% more aroma than the standard granules. The aroma profiles of the new and current format was found to be very similar. However, generally the compounds which show strong peaks in the current format show even stronger peaks in the new format. This means that the aroma is more intense, rather than having unusual notes.

[0149] For the liquid body of the reconstituted beverages (i.e. not the headspace), the measured total aroma were found to be relatively close between the new and current formats. That said, the new droplet format was found to contain slightly more. However, it is highly unlikely that such a small difference is perceivable.

[0150] The results obtained are highly interesting. Particularly the measured headspace over brew measurement which found a significant increase in aroma release in the cup made with the novel format FD instant when compared to the current format. Curiously, this significant difference was not identified during analysis of the liquid brew.

[0151] A hypothesis was created to explain the observations which revolves around the release of volatile aroma during the grinding & sifting steps during production of the current format. Much of the species driving the difference in measured aroma (eg 2- and 3-methylbutanal, 2- methylpropanal, acetaldehyde) have relatively low boiling points. It is known that the grinding of frozen coffee slabs to produce granules is an energy intensive process which introduces significant heat to the product alongside releasing a significant amount fine particles and dust. It is possible that, by avoiding this grinding step, a significant amount of aroma compounds are retained within the coffee. This theory could also extend to explain why similar aroma was measured in the liquid brews. If indeed these aroma compounds are highly volatile, they could be readily evaporated from the hot brewed coffee. In this case, the aroma compounds would be more readily detected in the headspace over the brew than in the liquid brew which matches what was observed.

[0152] It was concluded that:

[0153] • The new format rotary deposited drops were found to contain 33% greater total aroma in the headspace over the brew than the current format instant.

[0154] • The increased aroma detected in the headspace over the brew of the rotary deposited drops is likely the result of a gentler production process (elimination of the intensive grinding step).

[0155] The term “comprising” as used herein can be exchanged for the definitions “consisting essentially of” or “consisting of”. The term “comprising” is intended to mean that the named elements are essential, but other elements may be added and still form a construct within the scope of the claim. The term “consisting essentially of” limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed invention. The term “consisting of” closes the claim to the inclusion of materials other than those recited except for impurities ordinarily associated therewith.

[0156] The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art, and remain within the scope of the appended claims and their equivalents.

[0157] For the avoidance of doubt, the entire contents of all documents acknowledged herein are incorporated herein by reference.

Claims

Claims:1 . A method for the manufacture of a plurality of freeze-dried soluble coffee articles, the method comprising:(i) providing an aqueous coffee extract comprising at least 40wt% soluble coffee solids;(ii) foaming and cooling the aqueous coffee extract to form a foamed viscous coffee extract;(iii) depositing the foamed, viscous coffee extract onto a surface to form a plurality of individual coffee articles;(iv) freezing the plurality of individual coffee articles to form a plurality of frozen coffee articles; and(v) subliming water from the plurality of frozen coffee articles under a pressure of less than 0.7mbar, preferably 0.1 to 0.5mbar, to form a plurality of freeze-dried soluble coffee articles, each having a mass of 0.10g or less and a colour of less than 35 La, wherein, in step (iv) the freezing of the individual coffee articles includes a low temperature annealing step whereby the coffee articles remain within a temperature range of from -15 to -35eC for at least 20 minutes.

2. The method according to claim 1 , wherein the aqueous coffee extract has 45 to 65wt% soluble coffee solids, preferably 48 to 52wt% soluble coffee solids.

3. The method according to claim 1 or claim 2, wherein the foamed coffee extract:(a) has a density of from 400 to 900g / L, preferably 650 to 750g / L; and / or(b) is cooled in step (iii) to a temperature of 0 to -16°C, preferably -6 to -10°C.

4. The method according to claim (iv) wherein the plurality of individual coffee articles are initially cooled to a temperature below -30eC, preferably below -35eC, and then annealed in the low temperature annealing step at a temperature of -15 to -25eC.

5. The method according to any of claims 1 to 4, wherein step iv) comprises: a) individually depositing amounts of the viscous coffee extract onto a freezing belt, preferably using an extruder or rotary depositor; or b) extruding the viscous coffee extract onto the freezing belt and cutting it in situ to form the plurality of frozen coffee articles.

6. The method according to claim 5, wherein step (iv) comprises individually depositing amounts of the viscous coffee extract onto a freezing belt using an extruder and a cutter, whereby cut pieces of the viscous coffee extract fall onto the freezing belt and wherein the speed of the freezing belt is configured such that a majority of the cut pieces contacting the freezing belt are not in contact with another cut piece.

7. The method according to any of claims 1 to 6, wherein step (v) of subliming water is performed at an initial temperature of from -32 to -37°C, preferably about -35°C.

8. The method according to any of claims 1 to 7, wherein the method does not involve the recycling of fines material formed after or during step (iv) back into the process before step (iv).

9. A freeze-dried coffee article having a mass of 0.10g or less, a density of from 0.20 to 0.8 g / cm3, a colour of less than 35 La, and a substantially flat base having an area of from 1 mm2to 50mm2, wherein the article is symmetric about at least one plane of symmetry and / or axis of rotation.

10. The coffee article according to claim 9, wherein the article is dome-shaped and has a base radius of 0.5 to 4mm, preferably from 1 .5 to 2.5mm.11 . The coffee article according to claim 10, wherein the article has a ratio of height to the base radius of from 1 :4 to 5:4, preferably 1 :3 to 1 :1.

12. The coffee article according to claim 9, wherein the article has an axis and a substantially constant cross-section orthogonal to said axis a perimeter of said cross-section consisting of an arc and a chord, the chord forming the flat base, preferably wherein the arc is elliptical or circular, more preferably wherein the article has a ratio of height to the chord of from 1 :4 to 5:4, preferably 1 :3 to 1 :1.

13. The coffee article according to any of claims 9 to 12, wherein the article has a density of from 0.35 to 0.65g / cm3.

14. The coffee article according to any of claims 9 to 13, wherein the substantially flat base has a surface having a reduced gloss and / or increased porosity compared to an upper surface of the article.

15. The coffee article according to any of claims 9 to 14, having a colour of 18 to 30 La.

16. A coffee composition for forming a coffee beverage, the composition comprising a plurality of the coffee articles according to any preceding claim, preferably wherein a size distribution of the base radii of the coffee articles has a non-continuous distribution and, preferably has a multimodal distribution.

17. The coffee composition according to claim 16, having a bulk density of from 150 to 400g / L, preferably 210 to 250g / L.

18. The coffee composition according to claim 16 or claim 17, further comprising at least 10wt% of a conventional freeze-dried or spray-dried coffee powder.

19. The freeze-dried coffee article according to any of claims 9 to 15, obtainable by the method according to any of claims 1 to 8.

20. A method of forming a beverage, the method comprising dissolving the coffee composition according to any of claims 16 to 18 in water.

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