Soluble coffee powder

Abstract

The present invention relates to a soluble beverage powder comprising dry coffee extract particles having two substantially flat surfaces and a uniform thickness. Another aspect of the present invention is a method for making a freeze-dried soluble beverage powder.

Description

Technical Field

[0001] The present invention relates to a soluble beverage powder comprising dry coffee extract particles having two substantially flat surfaces and a uniform thickness. Another aspect of the present invention is a method for making a freeze-dried soluble beverage powder. Background Art

[0002] For many years, manufacturers of soluble coffee have been trying to improve the acceptance of this type of coffee relative to roasted and ground coffee. Many efforts have been made to optimize the flavor and aroma of soluble coffee, and due to the success of these technological advances, some soluble coffees are currently marketed as premium products. Premium products are products that consumers consider to be high quality and, in particular, luxurious.

[0003] However, progress in the appearance of soluble coffee has been slow. There is a need for technology that can achieve soluble coffee with a premium appearance, for example to accompany premium taste and aroma and enhance the consumer's experience in terms of visual recognition. In many countries, regulations require that pure soluble coffee can only consist of coffee. This presents a challenge in providing a novel and attractive appearance, as, for example, the inclusion of color pigments would not be allowed.

[0004] Any reference in this specification to prior art documents is not to be taken as an admission that such prior art is well-known technology or forms part of the common general knowledge in the art. As used in this specification, the words "include", "comprises" and similar words should not be construed as having an exclusive or exhaustive meaning. In other words, these words are intended to mean "including but not limited to". Summary of the invention

[0005] The object of the present invention is to improve the prior art and to provide an improved solution to provide a high-grade appearance of soluble beverage powders. The object of the present invention is achieved by the subject matter of the independent claims. The dependent claims further develop the idea of ​​the invention.

[0006] Accordingly, the present invention provides in a first aspect a soluble beverage powder comprising dry coffee extract particles having two substantially flat surfaces and a uniform thickness; wherein the particles have a median thickness of 0.1 mm to 10 mm, a surface roughness of less than 12 μm as measured by profilometry, and a uniformity index greater than 0.6 as measured by profilometry.

[0007] In a second aspect, the present invention relates to a method for manufacturing a freeze-dried soluble beverage powder, the method comprising the steps of: providing a liquid aqueous beverage composition (1) having a total solids content between 5% and 65%; forming a layer (2) of the liquid aqueous beverage composition located between and in contact with two parallel flat surfaces (3a, 3b), the surfaces being separated by a gap of 0.1 mm to 10 mm; cooling the layer of liquid aqueous beverage composition to below -25°C to form a frozen beverage composition; and drying the frozen beverage composition.

[0008] The inventors have surprisingly found that a liquid aqueous beverage composition can be dried so as to produce a soluble beverage powder having an attractive glossy appearance. The inventors have surprisingly found that drying a coffee extract in a manner that favors the formation of flat particles having a small open pore microstructure produces a soluble beverage powder having a lighter color. Specifically, the higher the proportion of open pores having an opening less than 4.5 microns, the lighter the color of the beverage particles. In the case where the beverage is coffee, the hue of the coffee extract combined with the lighter color and glossy surface forms an appearance similar to metallic gold and is therefore visually attractive. Gold has a unique appearance with the golden hue and specular reflective properties of polished metal. Historically, gold has been associated with wealth and luxury. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of an apparatus for forming and cooling a liquid beverage extract between two parallel planar surfaces.

[0010] Figure 2 is a schematic diagram of an apparatus for forming and cooling a liquid beverage extract in contact with a planar surface.

[0011] FIG3 shows an electron micrograph of sample A; Figure 3a shows the surface morphology of thin film frozen and vacuum dried coffee particles, resulting in a flat / smooth surface which gives the coffee particles a shiny glossy appearance; and Figure 3b The internal structure of a dried particle is shown. The voids are due to sublimation of ice crystals, many of which have diameters less than 4.5 micrometers. The scale bar is 10 micrometers.

[0012] Figure 4 is a graph of percent intrusion of mercury for Sample A (Y-axis) versus applied pressure (X-axis).

[0013] Figure 5 is a graph of lightness L* (Y-axis) measured as described in Example 4 versus median opening diameter in microns (X-axis). DETAILED DESCRIPTION

[0014] Accordingly, the present invention relates in part to a soluble beverage powder comprising (e.g., consisting of) dry coffee extract particles having two substantially planar surfaces (e.g., two planar surfaces) and a uniform thickness; wherein the particles have a median thickness of 0.1 mm to 10 mm (e.g., 0.15 mm to 5.0 mm, e.g., 0.2 mm to 3.0 mm, e.g., 0.2 mm to 1.5 mm, e.g., 0.25 mm to 0.5 mm), a surface roughness measured by profilometry of less than 12 μm (e.g., less than 10 μm, e.g., less than 8 μm, e.g., less than 6 μm), and a uniformity index measured by profilometry of greater than 0.6 (e.g., greater than 0.7).

[0015] In one embodiment, the soluble beverage powder is a freeze-dried soluble beverage powder.

[0016] In one embodiment, the dry coffee extract particles are freeze-dried coffee extract particles.

[0017] The soluble beverage powder may be a coffee mixture, for example the soluble beverage powder may be a coffee mixture comprising dry coffee extract and milk powder. The soluble beverage powder may be a coffee mixture comprising coffee and chicory. The soluble beverage powder may be a flavored coffee mixture, for example caramel or vanilla flavored. Many food regulations prohibit the presence of ingredients other than coffee material in pure soluble coffee. The soluble beverage powder may be pure soluble coffee, for example the soluble beverage powder may consist of dry coffee extract.

[0018] The coffee extract according to the present invention may be an aqueous coffee extract suitable for further processing into soluble coffee. Coffee extracts may be produced by extracting roasted coffee beans with water. Roasted beans are usually ground first and then extracted with water. The grinding of roasted coffee beans is well known in the art, and roasted coffee beans may be ground by any suitable method. Extraction may be performed by any suitable method known in the art. For example, methods for extracting coffee beans known in the field of soluble coffee production are known from EP0826308, and the method generally involves several extraction steps at elevated temperatures. When the desired degree of extraction is reached, the extracted roasted coffee beans are separated from the extract. Separation may be achieved by any suitable method, such as filtering, centrifuging and / or decanting. In conventional coffee extraction for producing soluble coffee, separation is usually achieved by extracting in an extraction chamber, in which the coffee grounds are held by a filter plate or a retaining plate, and the coffee extract may flow through the filter plate or the retaining plate. Before and / or during extraction, volatile aroma compounds may be recovered from coffee beans and / or extracts, for example, by stripping and / or using a vacuum, to avoid aroma loss. The recovered volatile compounds can be added back to the extract after extraction.

[0019] The coffee extract may be cold brew coffee, such as roasted coffee extracted at a temperature below 100°C, such as below 80°C, such as below 60°C, such as below 40°C, such as below 20°C.

[0020] The coffee extract may be an extract of roasted Arabica coffee beans, Robusta coffee beans or a combination of these coffee beans. Coffee beans are the seeds of the coffee plant (genus Coffea). By Arabica coffee beans are meant coffee beans from the Arabica coffee plant (Coffea arabica) and by Robusta coffee beans are meant coffee beans from the Robusta coffee plant (Coffea canephora).

[0021] The flat surface of the coffee extract particles causes them to exhibit the optical properties of polished metal - specular reflection. In the context of the present invention, the term "flat surface" refers to a horizontal surface without raised areas. The surface roughness can be measured by a wide area 3D profilometer using a pattern projection technique. The surface roughness is characterized by the parameter Sa (arithmetic mean height of the surface) using a definition corresponding to that in ISO 25178 [ISO 25178-2:2012, retrieved from https: / / www.iso.org / standard / 42785.html] and applying the following cut-off wavelength filters: λ5 = 8 μm and λ L = 0.8 mm calculated from the height map of the particle. The surface roughness Sa decreases as the surface becomes flatter. For example, a flat surface of a particle according to the invention may have a surface roughness of less than 12 μm measured by profilometry.

[0022] The thickness of the particle is considered in the direction perpendicular to the flat surface. The thickness can be measured by a microscope. Preferably, the thickness can be measured by a wide area 3D profilometer using a pattern projection technique.

[0023] The particles according to the invention each have a uniform thickness such that the uniformity index measured by profilometry is greater than 0.6, for example greater than 0.7. The uniformity index of a particle is calculated as the average thickness of the individual particles divided by the maximum thickness of the individual particles.

[0024] The particles according to the present invention may all have similar thicknesses. In one embodiment, the particles have an overall uniformity index greater than 0.6, for example greater than 0.7. The overall uniformity index is calculated from the median of the average thickness T of all individual particles and the maximum thickness T of all individual particles T according to the following equation 最大 Calculated by the median value of .

[0025]

[0026] In one embodiment, the particles have open pores with openings less than 4.5 microns, and the volume of open pores with openings less than 4.5 microns is greater than 50% of the total volume of open pores (e.g., greater than 60% of the total volume of open pores, such as greater than 70% of the total volume of open pores, such as greater than 80% of the total volume of open pores, such as greater than 90% of the total volume of open pores) as measured by mercury porosimetry. Using mercury intrusion measurement, the intrusion achieved at a pressure of 40 psia corresponds to the volume of open pores with openings greater than 4.5 microns. The volume of open pores with openings less than 4.5 microns can be greater than 0.75 ml / g (e.g., greater than 0.80 ml / g, such as greater than 0.85 ml / g, and further such as greater than 0.90 ml / g), as measured by mercury porosimetry. The volume of open pores with openings less than 4.5 microns can be 0.75 ml / g to 2.0 ml / g, such as 0.80 ml / g to 1.50 ml / g, and further such as 0.90 ml / g to 1.0 ml / g. Open pores in freeze-dried materials are usually the result of ice crystals sublimating during the drying process leaving voids or pores. Small open pores can form, for example, by rapid freezing to form small ice crystals.

[0027] In one embodiment, the total open pore volume of the particles is greater than 0.9 ml / g, such as greater than 0.95 ml / g, as measured by mercury porosimetry. The particles may have a total open pore volume of 0.9 ml / g to 2.1 ml / g (e.g., 0.95 ml / g to 1.4 ml / g, such as 1.0 ml / g to 1.2 ml / g), as measured by mercury porosimetry.

[0028] In one embodiment, the particles have open pores with openings less than 2 microns, and the volume of open pores with openings less than 2 microns is greater than 20% (e.g., greater than 30%, such as greater than 40%, such as greater than 50%, such as greater than 60%) of the total volume of open pores, as measured by mercury porosimetry. The volume of open pores of the particles with openings less than 2 microns may be 20% to 90%, such as 40% to 80%, such as 50% to 70% of the total volume of open pores, as measured by mercury porosimetry. Using mercury intrusion measurement, the intrusion achieved at a pressure of 90 psia corresponds to the volume of open pores with openings greater than 2 microns. The volume of open pores with openings less than 2 microns may be greater than 0.5 ml / g (e.g., greater than 0.6 ml / g, such as greater than 0.7 ml / g, such as greater than 0.7 ml / g), as measured by mercury porosimetry. The volume of open pores with openings less than 2 microns may be between 0.5 ml / g and 1.2 ml / g, such as between 0.6 ml / g and 1.1 ml / g, such as between 0.7 ml / g and 1.0 ml / g, as measured by mercury porosimetry.

[0029] In one embodiment, the particles have open pores with openings less than 4.5 microns but greater than 2 microns, and the volume of open pores with openings less than 4.5 microns but greater than 2 microns is 5% to 80%, such as 10% to 70%, such as 20% to 60%, and further such as 30% to 50% of the total open pore volume as measured by mercury porosimetry.

[0030] In one embodiment, the particles have a median open pore diameter of less than 4.5 microns (e.g., less than 4 microns, e.g., less than 3 microns, e.g., less than 2.5 microns, e.g., less than 2 microns, e.g., less than 1.7 microns), as measured by mercury porosimetry. The particles may have a median open pore diameter of 0.3 microns to 3.5 microns (e.g., 0.4 microns to 2.5 microns, e.g., 0.5 microns to 2 microns), as measured by mercury porosimetry. The median open pore diameter is the volume median diameter Dv50.

[0031] The openings may be needle-shaped. The needle-shaped holes may have a length exceeding 10 times the average diameter. "Length" and "diameter" may be measured by microscopy, for example by scanning electron microscopy combined with image analysis.

[0032] Polished metals exhibit specular reflection, wherein incident light is reflected in a single exit direction. Specular reflection is sometimes referred to as gloss. In one embodiment, the gloss of the soluble beverage powder at 60 ° geometry is at least 0.25 gloss units, such as at least 0.3 gloss units, such as at least 0.4 gloss units, such as at least 0.5 gloss units, and at least 0.6 gloss units. Gloss can be measured, for example, with illuminant CIE-C and CIE standard observers. Gloss can be measured using, for example, a BYK Gardner micro-triangle gloss meter equipped with a support suitable for cosmetic powders.

[0033] The CIE 1976 L*a*b* (hereinafter referred to as CIELAB) color scale is a method for measuring color proposed by the International Commission on Illumination [CIE Technical Report, Colorimetry 2 nd Edition, CIE 15.2–1986, corrected reprint 1996]. The CIELAB color space is created by plotting the quantities L*, a*, b* on rectangular coordinates. The L* coordinate of a target is the light intensity measured on a scale of 0 (black) to 100 (absolute white). The a* and b* coordinates do not have

[0034] The parameter a* ranges from pure green (negative a*) to pure red (positive a*), while the parameter b* ranges from pure blue (negative b*) to pure yellow (positive b*). In the CIELAB color space, the color difference can be calculated as a single value that takes into account the difference between the L*, a* and b* values ​​of the two samples. The color difference rE is calculated as follows:

[0035]

[0036] In one embodiment, the soluble beverage powder has a color difference ΔE from gold of less than 80 (e.g. less than 75, such as less than 70, such as less than 65). In one embodiment, the dry coffee extract particles have a color difference ΔE from gold of less than 80 (e.g. less than 75, such as less than 70, such as less than 65). In the context of the present invention, gold is considered to have CIELAB values ​​L*=86.9, a*=-1.9, and b*=87.1. This corresponds to the hexadecimal gold color code #ffd700 [World Wide Web document,<encycolorpedia.com / ffd700> , accessed on January 30, 2019]. Therefore, rE relative to gold is calculated from the measured values ​​of L*, a*, and b* as follows:

[0037]

[0038] Color measurements can be made with a commercially available colorimeter such as the HunterLab Colorflex (CX1051) device, for example, using a illuminant / observer set to D65 / 45°±2° and excluding specular reflections.

[0039] In one embodiment, the soluble beverage powder has an L* value greater than 40, for example a light intensity L* value greater than 45 as measured by a colorimeter such as a HunterLab Colorflex (CX1051) device. In one embodiment, the dry coffee extract particles have an L* value greater than 40, for example a light intensity L* value greater than 45 as measured by a colorimeter such as a HunterLab Colorflex (CX1051) device.

[0040] The inventors have found that by applying different cooling rates to the coffee extract during freezing, particles exhibiting more than one color, for example more than one light intensity, can be obtained. In one embodiment, the particles may be multi-colored, for example bi-colored. The particles may be multi-colored (for example bi-colored) on a single surface. The dried coffee extract particles may be bi-colored on opposite surfaces (for example, top and bottom), for example, the particles may have a substantially flat surface (for example as measured by a HunterLab Colorflex (CX1051) device) that exhibits an L* value of at least 1.2 times (for example at least 1.4 times, for example at least 1.6, for example at least 1.8 times, for example at least 2 times) that of opposite and parallel substantially flat surfaces.

[0041] In one embodiment, the soluble beverage powder is a glassy amorphous solid, for example a glassy amorphous solid at 20°C. In one embodiment, the dry coffee extract particles are a glassy amorphous solid, for example a glassy amorphous solid at 20°C. Glassy amorphous solids exhibit a glass transition temperature. The glass transition temperature can be measured, for example, by differential scanning calorimetry. The soluble beverage powder may be free of crystalline material, for example no crystals may be observed under a microscope using polarized light.

[0042] The soluble beverage powder may have a particle size distribution D(4,3) of 0.05 mm to 10 mm (e.g. 0.2 mm to 5 mm). The dried coffee extract particles according to the invention may have a particle size distribution D(4,3) of 0.05 mm to 10 mm (e.g. 0.2 mm to 5 mm). The particle size distribution D(4,3) may be measured by laser diffraction.

[0043] One aspect of the present invention provides a method for making a freeze-dried soluble beverage powder, the method comprising the steps of: providing a liquid aqueous beverage composition (1) having a total solids content between 5% and 65% (e.g., between 20% and 55%, e.g., between 30% and 50%); forming a layer (2) of the liquid aqueous beverage composition located between and in contact with two parallel flat surfaces (3a, 3b), the surfaces being separated by a gap of 0.1 mm to 10 mm (e.g., between 0.2 mm and 2.5 mm, between 0.3 mm and 2.0 mm, between 0.5 mm and 1.5 mm); cooling the layer of the liquid aqueous beverage composition to below -25°C (e.g., below -30°C, e.g., below -35°C, e.g., below -40°C) to form a frozen beverage composition; and drying the frozen beverage composition (e.g., under vacuum). The liquid aqueous beverage composition can be cooled, for example, by contact with frozen parallel flat surfaces (4a, 4b) (e.g., two parallel solid flat surfaces of cooling). Freezing the aqueous beverage composition between the two parallel flat surfaces of freezing produces a frozen sheet with flat sides. When frozen, the open surface will have a higher surface roughness. The method of the present invention advantageously provides freeze-dried beverage particles with a microstructure of uniform flat surfaces and open pores providing a unique appearance. The liquid aqueous beverage composition can be pre-frozen before being formed into a layer.

[0044] Preferably, the liquid aqueous beverage composition is free-flowing and not a paste. The shear forces required to distribute a pasty material on a flat surface to form a layer will disrupt the formation of flat particles with a microstructure of small openings. The liquid aqueous beverage composition may have a viscosity of less than 1500 mPa.s (e.g., less than 1000 mPa.s) at 75 s at the temperature immediately before forming into a layer. -1 For example, the measurement is performed using an Anton Paar rheometer.

[0045] The liquid aqueous beverage composition may comprise less than 1 wt. % solid ice immediately prior to being formed into a layer.

[0046] The liquid aqueous beverage composition may, for example, be selected from the group consisting of: a dairy beverage, a beverage creamer, a plant milk, a plant extract, and a combination thereof. The plant extract may be, for example, an aqueous tea (Camellia sinensis)

[0047] extracts), herbal teas (aqueous infusions made from leaves, barks, roots, berries, seeds, and spices (e.g., mint, chamomile, verbena, and rooibos)), aqueous extracts of coffee berry pulp or peel (Champaca cascara), coffee extracts, and combinations thereof.

[0048] In one embodiment, the aqueous beverage composition is a coffee extract, for example the frozen beverage composition may be a frozen coffee extract.

[0049] In one embodiment, the present invention provides a method for making a freeze-dried soluble beverage powder, the method comprising the steps of: providing a liquid coffee extract (1) having a total solids content of between 5% and 65% (e.g. between 20% and 55%, e.g. between 30% and 50%); forming a layer (2) of the liquid coffee extract located between and in contact with two parallel flat surfaces (3a, 3b), the surfaces being separated by a gap of 0.1 mm to 10 mm (e.g. between 0.2 mm and 2.5 mm, between 0.3 mm and 2.0 mm, between 0.5 mm and 1.5 mm); cooling the layer of liquid coffee extract to below -25°C (e.g. below -30°C, e.g. below -35°C, e.g. below -40°C) to form a frozen coffee extract; and drying the frozen coffee extract (e.g. under vacuum). The coffee extract may be cooled, e.g., by contact with the frozen parallel flat surfaces (4a, 4b). The liquid coffee extract may be pre-frozen before being formed into a layer.

[0050] The liquid coffee extract according to the present invention may be an aqueous coffee extract suitable for further processing into soluble coffee.

[0051] The solid content of an aqueous beverage composition (e.g., coffee extract) is the weight of dry matter as a percentage of the total weight of the composition on a wet basis. Various methods can be used to increase the solid content of an aqueous beverage composition (e.g., coffee extract). For example, water can be evaporated from the aqueous beverage composition under vacuum. Evaporation can be performed together with aroma capture. Water can be removed via membrane concentration, or another solid beverage composition (e.g., dry coffee extract) can be dissolved in an aqueous beverage composition (e.g., aqueous coffee extract).

[0052] In one embodiment, the aqueous beverage composition is a coffee extract having 50 wt% to 65 wt% solids and is the result of adding dried pure soluble coffee to the aqueous coffee extract.

[0053] The planar surface (3a, 3b) in contact with the liquid aqueous beverage composition may have a surface roughness measured by profilometry of less than 12 μm, such as less than 10 μm, such as less than 8 μm, such as less than 6 μm.

[0054] The frozen beverage composition (e.g., frozen coffee extract) may be broken up before drying, for example, it may be broken up into particles in the frozen state. The dried beverage composition (e.g., dried coffee extract) may be broken up. The beverage composition may first be broken up in the frozen state and then also in the dried state. In one embodiment, the freeze-dried soluble beverage powder may have a particle size D(4,3) of 0.05 mm to 10 mm.

[0055] Gas can be supplied to the liquid aqueous beverage composition (e.g., liquid coffee extract) before it is formed into a layer, for example, gas can be added to the liquid aqueous beverage composition by means of a gas addition pipeline, wherein the gas is slightly higher than the pressure of the aqueous beverage composition. When adding gas, the aqueous beverage composition can be under a pressure higher than atmospheric pressure, so that the release of pressure causes the formation of foam. When formed into a layer, the liquid aqueous beverage composition can be foam. Foaming the aqueous beverage composition before freeze drying can be used to accelerate the drying time and enhance the dissolution characteristics of the final beverage powder. The gas can be selected from the group consisting of: nitrogen, air, argon, nitrous oxide and carbon dioxide. For example, the gas can be carbon dioxide. For example, the gas can be nitrogen.

[0056] In one embodiment, the flat surfaces are moving belts (6a, 6b) that convey a beverage composition (e.g., coffee extract) between the flat surfaces, for example. In one embodiment, cooling is applied to at least one of the moving belts, for example, cooling may be applied to the surface of the belt opposite to the surface in contact with the beverage composition (e.g., coffee extract). Cooling may be applied to the surface in contact with the beverage composition by a cooling plate (4a) on the opposite surface of the belt. Cooling (4a, 4b) may be applied to both moving belts. The belts may be controlled, for example, using a drive system (7a, 7b) for the connection of the belts, so that these move together. The belts may be formed of any suitable material, for example, a material for a conveyor belt in contact with food. The belts may be metal. The belts may be plastic. The belts may have a non-stick surface, for example, the belts may be coated with polytetrafluoroethylene or silicon.

[0057] In one embodiment, a stronger cooling is applied to one moving belt than the other moving belt, for example, so that two opposite surfaces of a beverage composition (e.g., coffee extract) are subjected to different cooling rates. Faster cooling of the beverage composition (e.g., coffee extract) results in the generation of smaller ice crystals. The ice crystal size controls the size of the openings formed after freeze drying. By producing holes of different sizes on opposite sides of the freeze-dried extract (e.g., top and bottom flat surfaces), visually attractive bicolor particles can be produced. Cooling can be applied to the first moving belt by a first cooling plate (4a) and to the second moving belt by a second cooling plate (4b), the second cooling plate being positioned directly opposite to the first cooling plate, wherein the temperature difference between the first cooling plate and the second cooling plate is at least 5°C, for example at least 10°C.

[0058] In one embodiment, the belt passes through multiple cooling zones. Multiple cooling zones allow for precise control of beverage composition cooling. For example, a first moving belt may pass over another cooling plate (5a), and a second cooling belt may pass over another cooling plate (5b). In one embodiment, the moving belt does not pass through a heating zone. The cooling zones gradually cool the liquid aqueous beverage composition.

[0059] In one embodiment, the moving belts are oriented vertically and a liquid aqueous beverage composition (e.g., liquid coffee extract) is fed between the belts at the top and conveyed downwardly in contact with the moving belts to form a frozen beverage composition (e.g., frozen coffee extract) that is discharged from the bottom (8).

[0060] In another aspect of the invention, the process of the invention described above may be used to manufacture a soluble beverage powder of the invention.

[0061] A further aspect of the invention provides a method for making a soluble beverage powder of the invention, the method comprising the steps of providing a liquid coffee extract (1) having a total solids content of between 5% and 65% (e.g. between 20% and 55%, e.g. between 30% and 50%); forming a layer (2) of the coffee extract in contact with a flat surface (3), the coffee extract layer having a thickness of 0.1 mm to 10 mm (e.g. between 0.2 mm and 2.5 mm, between 0.3 mm and 2.0 mm, between 0.5 mm and 1.5 mm); cooling the coffee extract layer to below -25°C (e.g. below -30°C, below -35°C, below -40°C) to form a frozen coffee extract; and drying the frozen coffee extract (e.g. under vacuum). The coffee extract may be cooled, for example, by contact with a cooled flat surface. The flat surface may, for example, be a moving belt (6) conveying the coffee extract. In one embodiment, cooling is applied to the moving belt, for example, cooling may be applied below the belt with which the coffee extract contacts. Cooling may be applied to the belt by means of cooling plates (4, 5).Air cooling (9) may be applied to the coffee extract layer, for example the coffee extract layer may be on top of a cooled moving belt, leaving an exposed top coffee layer surface to which cooling air is applied.

[0062] Those skilled in the art will appreciate that they are free to incorporate all features of the present invention disclosed herein. In particular, features described for product of the present invention may be combined with method of the present invention, and vice versa. In addition, features described for different embodiments of the present invention may be combined. If known equivalents exist for specific features, such equivalents are incorporated, as are explicitly mentioned in this specification.

[0063] Further advantages and features of the invention will become apparent upon reference to the accompanying drawings and non-limiting examples.

[0064] Example

[0065] Example 1: Process for preparing soluble beverage powder

[0066] exist Figure 1 The device shown has a liquid coffee extract with a solid content of 40% dry matter fed (1) between two moving belts (6a, 6b). The gap between the two moving belts is set to 1.1 mm. The feed rate of the liquid coffee extract is 100 g / min. The temperature of the coffee extract is 20°C. The speed of the two moving belts is adjusted by the connected drive system (7a, 7b) so that the total residence time of the coffee liquid in the device is 2 min.

[0067] Cooling plates (4a, 4b, 5a, 5b) positioned in contact with the moving belt on the side opposite to the extract cool the extract. The first cooling plates (4a, 4b) are both set to 0°C and the second plates (5a, 5b) are set to -77°C. The cooling plates are cooled by recirculating liquid coolant. The formation of ice crystals occurs mainly between the second plates (5a, 5b) forming a solid layer of frozen coffee extract. Since the coffee extract is trapped and frozen between the two moving belts, a thin and flat coffee extract sheet is formed after freezing; it has a thickness of 1.07 mm.

[0068] After the frozen coffee ice flakes were discharged from the apparatus (8), they were collected and ground to a particle size D (4,3) of about 1 mm. The ground frozen coffee extract was then vacuum dried using typical coffee freeze drying conditions to form sample A. The sample was in the form of particles having a flat, shiny surface.

[0069] Additional samples were prepared in the same manner, except that the cooling temperature and the gap between the belts were varied.

[0070] sample Temperature of the first zone (plates 4a, 4b) Temperature of the second zone (plates 5a, 5b) gap A 0℃ -77℃ 1.1mm B -5℃ -77℃ 0.7mm C -25℃ -60℃ 1.4mm

[0071] The samples were examined using a scanning electron microscope. The SEM image of sample A is shown in Figure 3. It can be observed that a flat surface was obtained. Small openings are visible.

[0072] Example 2: Measuring surface profile

[0073] The thickness and morphology of the particles were measured using a Keyence VR5200 wide area 3D profilometer using pattern projection technology.

[0074] The thickness of the particles is measured. At least 100 particles are placed manually on the black measuring stage of the device, which is defined as the reference plane. The particles do not touch each other. The brightness is adjusted at 5ms, the high magnification camera x40 is selected and the high resolution roughness mode is activated. The measurement is then performed and a height map with a pixel size of 3.7μm is obtained. The volume and area modules allow to obtain statistics for all individual coffee particles. The median sample thickness T is calculated from the median thickness of the individual particles. The maximum thickness T 最大 The median value of is obtained from the maximum height of all particles.

[0075] Use the Sa definition from the ISO 25178 document and apply the following cut-off wavelength filter: λ s =8μm and λ L= 0.8 mm, the surface roughness Sa was calculated from the measured height map of the particles. A broad region of interest was manually drawn on each measured particle, and the average roughness of multiple particles was reported.

[0076] Finally, the uniformity index UI is calculated based on the median of the average particle thickness and the median of the maximum particle thickness:

[0077]

[0078] For very flat particles with uniform thickness, this exponent is close to 1.

[0079] The results for the samples are listed in the table below. In addition, a commercial soluble coffee product with a flat surface (commercial sample i) and a standard freeze-dried coffee (commercial sample ii) were measured for comparison.

[0080] sample Median thickness (μm) Surface roughness(μm) Uniformity Index A 575 1.8 0.75 B 450 2.5 0.71 C 699 4.0 0.72 Commercial Samples 739 12.7 0.78 Commercial Samplesii 687 16.5 0.56

[0081] The roughness of the sample according to the invention is less than that of the flat commercial sample i or the standard commercial sample ii.

[0082] Example 3: Measurement of pore structure using mercury porosimetry

[0083] The structure evaluation was performed using an AutoPore IV 9520 (Micromeritics Inc. Norcrose, GA, USA). The operating pressure for mercury intrusion was 0.4 psia to 9000 psia (where the low pressure port was 0.4 psia to 40 psia and the high pressure port was 20 psia to 9000 psia). The pore diameter at this pressure ranged from 500 microns to 0.01 microns. The data reported are the total pore volume and the pore volume (ml / g) at different pore opening diameters (μm). About 0.1 g to 0.4 g of the sample was accurately weighed and loaded into a penetrometer (volume 3.5 ml, neck or capillary rod diameter 0.3 mm, rod volume 0.5 ml).

[0084] After the penetrometer was inserted into the low pressure port, the sample was initially evacuated at a rate of 1.1 psia per minute, then switched to a medium rate of 0.5 psia per minute, and then to a fast rate of 900 μm Hg per minute. The evacuation target was 60 μm Hg. After reaching the target, evacuation continued for 5 minutes before introducing Hg. The measurement was performed under set time balance. That is, in the set time balance (10 seconds) mode, the pressure point at which data is to be obtained and the elapsed time at that pressure. Approximately 140 data points were collected over the pressure range.

[0085] The volume of open pores per gram of product in the diameter range of 1 micrometer (μm) to 500 micrometers (μm) yields the "open pore volume".

[0086] The benchmark values ​​were obtained by running the corresponding air penetrometer under the same operating pressure conditions of Hg intrusion (0.4 psia to 9000 psia without any sample).

[0087] Figure 4 A graph showing the relationship between the percentage of intrusion and pressure for sample A is shown in FIG.

[0088] The results for the samples are listed in the table below.

[0089]

[0090] Compared to the commercial sample, the sample according to the invention has a much higher proportion of openings less than 2 microns and openings less than 4.5 microns. Compared to the commercial sample, the sample according to the invention also has a much smaller median opening diameter.

[0091] Example 4: Color and Appearance

[0092] The color of the sample was measured using a HunterLab Colorflex (CX1051) device, using an illuminant / observer set to D65 / 45°±2° and a 47 mm sample holder. The color difference rE from gold was calculated from the measured values ​​of L*, a* and b* (repeated three times) as follows:

[0093]

[0094] The specular reflection of the sample was measured using a BYK Gardner micro tri-angle gloss meter equipped with a support suitable for cosmetic powders. Gloss was measured with 60° incident light, CIE-C illuminant and CIE standard observer. The instrument was calibrated with a standard black sheet with a specified gloss value of 100 gloss units. For the measurement, the powder was placed in a measuring cup, its surface was leveled, and then the gloss meter was mounted, ensuring a tight fit to exclude room lighting. This procedure was repeated 6 times for each sample.

[0095] The results of L*a*b* value, difference from gold color, and glossiness are shown below.

[0096] Table 1

[0097] sample L* a* b* ΔE with gold 60° gloss unit A 55.0 8.0 25.0 70.5 0.68 B 47.8 9.1 24.5 74.6 0.62 C 40.4 9.9 23.8 79.3 0.47 Commercial Samples 31.8 11.6 19.8 88.0 0.38 Commercial Samplesii 31.4 11.5 20.8 87.5 0.23

[0098] It can be seen that the sample according to the invention is lighter, closer to gold in color and more lustrous than the commercial sample.

[0099] The L* and median pore size of a series of freeze-dried coffee powders prepared by various methods including the method of the present invention are plotted. The results are shown in Figure 5 It can be seen that the brightness decreases as the median pore size increases.

[0100]

[0046] Various features and embodiments of the invention will now be described with reference to the following numbered paragraph(s).

[0101] 1. A soluble beverage powder comprising dry coffee extract particles, wherein the particles have open pores having openings less than 4.5 microns, the volume of the open pores having openings less than 4.5 microns being greater than 50% of the total open pore volume as measured by mercury porosimetry.

[0102] 2. A soluble beverage powder according to paragraph 1, wherein the particles have open pores with openings less than 2 microns, the volume of the open pores with openings less than 2 microns being greater than 20% of the total open pore volume as measured by mercury porosimetry.

[0103] 3. A soluble beverage powder according to any of paragraphs 1 to 2, wherein the particles have a median open pore diameter of less than 4.5 microns as measured by mercury porosimetry.

[0104] 4. A soluble beverage powder according to any of paragraphs 1 to 3, having a gloss of at least 0.25 gloss units at 60° geometry.

[0105] 5. The soluble beverage powder according to any of paragraphs 1 to 4, having a color difference ΔE from gold of less than 80.

[0106] 6. A soluble beverage powder according to any one of paragraphs 1 to 5, wherein the particles are bi-coloured.

[0107] 7. A soluble beverage powder according to any of paragraphs 1 to 6, comprising dry coffee extract particles having two substantially flat surfaces and a uniform thickness; wherein the particles have a median thickness of 0.1 mm to 10 mm, a surface roughness measured by profilometry of less than 12 μm (e.g. less than 10 μm, e.g. less than 8 μm, e.g. less than 6 μm), and a uniformity index measured by profilometry greater than 0.6 (e.g. greater than 0.7).

[0108] 8. A method for producing a soluble beverage powder according to any one of paragraphs 1 to 7, the method comprising the steps of:

[0109] a. providing a liquid coffee extract (1) having a total solids content of between 5% and 65% (e.g. between 20% and 55%, e.g. between 30% and 50%);

[0110] b. forming a layer (2) of the coffee extract in contact with the flat surface (3), the coffee extract layer having a thickness of 0.1 mm to 10 mm (e.g. between 0.2 mm and 2.5 mm, between 0.3 mm and 2.0 mm, between 0.5 mm and 1.5 mm);

[0111] c. cooling the coffee extract layer to below -25°C (e.g., below -30°C, below -35°C, below -40°C) to form a frozen coffee extract; and

[0112] d. Drying the frozen coffee extract (eg, under vacuum).

[0113] 9. A method for producing a soluble beverage powder according to any one of paragraphs 1 to 7.

[0114] The method comprises the following steps:

[0115] a. providing a liquid coffee extract (1) having a total solids content between 5% and 65%;

[0116] b. forming a layer (2) of the coffee extract located between and in contact with two parallel flat surfaces (1.3a, 1.3b), the surfaces being separated by a gap of 0.1 to 10 mm;

[0117] c. cooling the coffee extract layer to below -25°C to form a frozen coffee extract; and

[0118] d. Drying the frozen coffee extract.

[0119] 10. The method according to paragraph 9, wherein the flat surface is a moving belt (6a, 6b).

[0120] 11. The method according to paragraph 10, wherein cooling (4a, 4b) is applied to at least one moving belt.

[0121] 12. The method of paragraph 11, wherein more intense cooling is applied to one moving belt than to the other moving belt.

[0122] 13. The method of any of paragraphs 9 to 12, wherein the belt passes through a plurality of cooling zones.

[0123] 14. A method according to any one of paragraphs 9 to 13, wherein the belts are oriented vertically and the liquid coffee extract is fed between the belts at the top and conveyed downwardly in contact with the moving belt to form a frozen coffee extract that is discharged from the bottom (8).

Claims

1. A soluble coffee powder comprising dry coffee extract particles having two substantially flat surfaces and a uniform thickness; wherein the particles have a median thickness of 0.2 mm to 1.5 mm, a surface roughness of less than 12 μm as measured by profilometry, and a uniformity index greater than 0.6 as measured by profilometry; The coffee powder is prepared according to a method comprising the following steps: a. Providing a liquid aqueous coffee composition (1) having a total solids content between 30% and 50%; b. forming a layer (2) of the liquid aqueous coffee composition located between and in contact with two parallel flat surfaces (3a, 3b), the surfaces being separated by a gap between 0.1 mm and 1.5 mm; c. cooling the liquid aqueous coffee composition layer to below -25°C to form a frozen coffee composition; and d. drying the frozen coffee composition; wherein the flat surfaces (3a, 3b) are moving belts (6a, 6b) and cooling is applied to both moving belts (6a, 6b) and stronger cooling is applied to one moving belt so that two opposing surfaces of the coffee composition are subjected to different cooling rates; wherein the temperature difference is at least 10°C.

2. A soluble coffee powder according to claim 1, wherein the particles have open pores with openings less than 4.5 microns as measured by mercury porosimetry, the volume of the open pores with openings less than 4.5 microns being greater than 50% of the total volume of open pores.

3. The soluble coffee powder of claim 1, wherein the particles have open pores having openings less than 2 microns as measured by mercury porosimetry, the volume of the open pores having openings less than 2 microns being greater than 20% of the total volume of open pores.

4. The soluble coffee powder of claim 1, wherein the particles have a median open pore diameter of less than 4.5 microns as measured by mercury porosimetry.

5. The soluble coffee powder of claim 1 having a gloss of at least 0.25 gloss units at 60° geometry.

6. The soluble coffee powder according to claim 1, having a color difference ΔE from gold color below 80.

7. The soluble coffee powder of claim 1, wherein the particles are bi-colored.

8. A method for producing freeze-dried soluble coffee powder, the method comprising the steps of: a. Providing a liquid aqueous coffee composition (1) having a total solids content between 30% and 50%; b. forming a layer (2) of the liquid aqueous coffee composition located between and in contact with two parallel flat surfaces (3a, 3b), the surfaces being separated by a gap of 0.1 mm to 1.5 mm; c. cooling the liquid aqueous coffee composition layer to below -25°C to form a frozen coffee composition; and d. drying the frozen coffee composition; wherein the flat surfaces (3a, 3b) are moving belts (6a, 6b), and wherein cooling is applied to both moving belts (6a, 6b) and more intense cooling is applied to one moving belt such that two opposing surfaces of the coffee composition are subjected to different cooling rates; wherein the temperature difference is at least 10°C.

9. The method of claim 8, wherein the moving belt passes through a plurality of cooling zones.

10. The method according to claim 8, wherein the moving belts are oriented vertically and the liquid aqueous coffee composition is fed between the moving belts at the top and conveyed downwardly in contact with the moving belts to form a frozen coffee composition discharged from the bottom (8).

11. The method according to claim 8, wherein the freeze-dried soluble coffee powder is a soluble coffee powder according to any one of claims 1 to 7.

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