METHOD OF PREPARING A MILK-BASED LIQUID

Abstract

The invention concerns a method for producing a milk-based liquid in a beverage preparation apparatus, said apparatus comprising : - at least one mixing chamber configured for producing a liquid by receiving and mixing a dose of soluble powder with water and by dispensing the reconstituted liquid, wherein the method comprises the steps of : - producing a first part of the milk based liquid by supplying the mixing chamber with a dose of soluble dairy milk powder and water so as to reconstitute a dairy milk and dispensing said first part made of dairy milk, and - producing a second part of the milk based liquid by supplying the mixing chamber with a dose of soluble plant-based milk powder and water so as to reconstitute a plant based milk and dispensing the second part made of plant-based milk, wherein the first and the second parts of the milk based liquid are mixed together to form the final milk based liquid.

Description

[0001] METHOD FOR PREPARING MILK BASED LIQUID

[0002] Field of the invention

[0003] The present invention relates to the preparation of a milk based liquid with a beverage preparation machine.

[0004] Background of the invention

[0005] In the field of preparation of coffee-based beverages, milk is frequently proposed as an additive to the coffee base to create various beverages such as cappuccino, latte macchiato, etc ... Usually, cow or dairy milk is provided and mixed with coffee, yet the sustainability impact of this type of milk is criticized nowadays.

[0006] As an alternative, plant based milks can be used, but their taste do not always please the consumers. In addition, these types of milk are hardly foamable. Consequently, simply replacing dairy milks by plant-based milks in coffee-based beverages is not sufficient to convince the consumers to change their habits.

[0007] An object of the invention is to address the above existing problem.

[0008] Summary of the invention

[0009] There is provided a method for producing a milk based liquid in a beverage preparation apparatus, said apparatus comprising :

[0010] - at least one supply of soluble plant-based milk powder or plant-based milk concentrate,

[0011] - at least one supply of soluble dairy milk powder or dairy milk concentrate,

[0012] - a water supply system,

[0013] - at least one mixing chamber configured for producing a liquid by receiving and mixing a dose of soluble powder or concentrate with water and by dispensing the reconstituted liquid, wherein the method comprises the steps of :

[0014] - producing a first part of the milk based liquid by supplying the mixing chamber with a dose of soluble dairy milk powder or dairy milk concentrate and water so as to reconstitute a dairy milk and dispensing said first part made of dairy milk, and

[0015] - producing a second part of the milk based liquid by supplying the mixing chamber with a dose of soluble plant-based milk powder or plant-based milk concentrate and water so as to reconstitute a plant based milk and dispensing the second part made of plant-based milk, wherein the first and the second parts of the milk based liquid are mixed together to form the final milk based liquid.

[0016] Accordingly, the method in the beverage apparatus enables the preparation of a milk based beverage wherein a first part is dairy milk and a second part is plant based milk. The final milk based beverage owns sensory characteristics of a dairy milk but presents a more sustainable impact because for the same volume of final liquid, it requests the use of less dairy milk.

[0017] The overall taste of the final milk based liquid balances the dairy and vegetal notes with a smoother and more delicate body than dairy milk. It can be used for the preparation of a coffeebased beverage coffee to equilibrate the coffee taste without the consumers noting an important difference with the use of current dairy milk.

[0018] In order to implement the method, the beverage preparation apparatus comprises at least one supply of soluble plant-based milk powder or plant-based milk concentrate and at least one supply of soluble dairy milk powder or dairy milk concentrate.

[0019] Usually, the supply comprises a storing container and a dosing device configured to dispense a dose of powder or concentrate in the mixing chamber.

[0020] For powders, the supply can be a canister configured to store, dose and dispense the dose of powder. The canister can comprise a dosing auger, a dosing screw or any powder dosing device.

[0021] For concentrates, the supply can be a storing container, such as a tank or a bag-in-box container, connected to a dispensing tube. Liquid concentrate dosing through the tube can be controlled with a pump or a peristaltic pump.

[0022] The apparatus can comprise different dairy milk containers storing different types of dairy milk powders or concentrates (different by their fat levels such as full fat milk powder, skimmed milk powder, ...). For the preparation of the first part of dairy milk, the dose of dairy milk powder supplied to the mixing chamber can be supplied from one of these containers or from more than one of these containers.

[0023] Similarly, the apparatus can comprise different plant based milk containers storing different types of plant based milk powders or concentrates (different by their origins such as oat milk powder, rice milk powder ...). For the preparation of the second part of plant-based milk, the dose of plant based milk powder or concentrate supplied to the mixing chamber can be supplied from one of these containers or from more than one of these containers.

[0024] Combination of different powders or concentrates can answer nutrition demand of the consumers (low fat level of the beverage) or optionally can answer a demand for a certain taste.

[0025] The beverage preparation apparatus comprises at least one mixing chamber configured to receive a dose of soluble powder or concentrate and a diluent, usually water, and to mix them in order to dissolve the soluble powder to reconstitute a liquid or dilute the concentrate. The mixing chamber is designed so as to make an efficient contact of the soluble powder and the diluent and improve the dissolution of the soluble powder or an efficient contact of the concentrate and the diluent and improve the dilution of the concentrate.

[0026] Preferably the mixing chamber comprises a whipper to improve mixing of the diluent and the powder or the concentrate and optionally enable foaming of the reconstituted liquid.

[0027] The mixing chamber comprises one outlet for dispensing the reconstituted liquid. Generally, this outlet is connected to a tube for dispensing the liquid to a container such as a drinking cup.

[0028] The water supply system of the apparatus usually comprises a water supply, such as a tank or a connection to tap water, a pump and a device to control the temperature of water supplied to the mixing chamber such as a water heater and / or a water cooler. When the beverage preparation apparatus comprises more than one mixing chamber, this water supply system is connected to each mixing chamber of the beverage preparation apparatus.

[0029] The method for preparing the milk based liquid comprises the step of preparing the first dairy milk and the step of preparing the second plant-based milk separately before mixing these two milks together to form the final milk based liquid.

[0030] Generally, the first part (dairy milk) of the milk based liquid represents 30 to 70 % in volume of the final milk based liquid. The second part (plant-based) is the complementary part of the first part (dairy) in the milk based liquid produced by the beverage preparation apparatus.

[0031] Percentage can be adapted depending on the specific taste of each used plant-based milk of the second part since some plant-based milks presents a stronger taste than others.

[0032] Preferably, the first part (dairy milk) of the milk based liquid represents 50 to 70 % in volume of the final milk based liquid. Within this preferred range of percentage, the taste of the plantbased milk part does not impact too much the taste of the final beverage.

[0033] The percentage in volume of the second part (plant-based milk) can be higher than 50 % if it is desired to create taste profiles different from usual dairy milk, with an increase of vegetal notes and a decrease of dairy notes.

[0034] The first dairy part can be produced from a mixture of different soluble dairy milk powders or concentrates such as a mixture of full fat and skimmed.

[0035] In the same manner, the second plant-based part can be produced from a mixture of different plant based milk powders or concentrates such as a mixture for example of oat milk powder and rice milk powder. According to one preferred embodiment of the method :

[0036] - in a first step, the first part of the milk based liquid is produced and dispensed in a container, and

[0037] - in a second step, the second part of the milk based liquid is produced and dispensed in the same container.

[0038] In this preferred embodiment, the container is successively filled with the first dairy milk part and then the second plant-based milk part to form the final milk based liquid.

[0039] This order of preparation avoids the problem of sedimentation of the second plant-based part once this second part has been reconstituted. Actually, often plant-based milk comprises small particles that can settle in the container after a certain time. By dispensing the second plantbased milk part inside the already prepared first dairy milk part present inside the container, the waiting time of the second part during the preparation is reduced and the risk of sedimentation is controlled. Once the preparation of the milk based liquid is finished, an additional coffee component can be added immediately inside the container, for example to prepare a cappuccino beverage.

[0040] These two steps of preparation of the milk based liquid can be implemented successively by means of the same mixing chamber or can be implemented in two different mixing chambers successively operated.

[0041] Preferably, according to this embodiment, during the first step, the first dairy milk part is foamed.

[0042] It has been observed that the foaming properties of reconstituted plant-base milks are quite inferior to the foaming properties of reconstituted dairy milks. In addition, even if plant-based milk powders or concentrates are mixed and foamed with dairy milk powders or concentrates, the foam properties of the final milk-based liquid present poor qualities.

[0043] By preparing the two different milk types separately, it is possible to obtain a final milk-based liquid presenting foaming qualities similar to those of a foamed dairy milk.

[0044] It is preferred that the second plant-based milk part is dispensed in the already dispensed foamed first dairy milk part so that the poor quality of said second part is not made apparent during the filling operation of the container.

[0045] Preferably, the method is implemented in a beverage preparation apparatus that comprises at least two mixing chambers, and wherein one first mixing chamber is configured to be supplied by the supply of soluble dairy milk powder or concentrate and is dedicated to the reconstitution of the first part of the milk based liquid, and wherein one second chamber is configured to be supplied by the supply of soluble plant based milk powder or concentrate and is dedicated to the reconstitution of the second part of the milk based liquid.

[0046] Preferably, the preparation steps in the first and second chambers start successively so that the first dairy milk part is prepared and dispensed before the second plant-based milk part.

[0047] As a result of the use of two mixing chambers, the preparation of the final milk based liquid can be reduced compared to the two successive preparations of the two parts of milk in the same mixing chamber. In addition, each mixing chamber can be optimally designed for each type of powder or concentrate. It is particularly the case for the mixing chamber designed to dissolve and optionally foam the plant-based milk powder or concentrate. By default, both mixing chambers can present the same design which design is optimally designed to dissolve and foam the plant-based milk powder or concentrate.

[0048] Preferably, at least one mixing chamber of the beverage preparation apparatus comprises :

[0049] - a dissolution chamber comprising an inlet for powder or concentrate, a water inlet connected to the water supply system and an outlet for reconstituted liquid,

[0050] - a whipper housing, a whipper and a backwall, the whipper housing and the back wall forming a whipper chamber in which is lodged the whipper, and the whipper housing comprising an inlet connected to the outlet of the dissolution chamber and a beverage outlet,

[0051] - a drive shaft for driving the whipper, said drive shaft being supported by the back wall, and wherein :

[0052] - the whipper presents a radial back surface facing the whipper housing back wall and a radial front surface opposed to the radial back surface,

[0053] - the whipper housing comprises a front wall, said front wall facing the radial front surface of the whipper.

[0054] The mixing chamber comprises a dissolution chamber designed to receive a dose of powder or concentrate and water to reconstitute the liquid milk. The outlet of this dissolution chamber is attached to the inlet of the whipper housing. The dissolution chamber and the whipper housing can be moulded in one single piece.

[0055] In such a mixing chamber, the whipper housing and the back wall are configured for forming a whipper chamber when they are assembled together. The mixing chamber comprises a whipper or whipper for whipping the liquid in reconstitution, such as an impeller or a rotating disk. The whipper is driven by a driveshaft of a motor and this driveshaft is supported by the back wall of the mixing chamber. The whipper housing presents a front wall that faces the radial front surface of the whipper. The whipper housing comprises an inlet through which the liquid in reconstitution is introduced for being whipped by the whipper. The inlet is generally present in the front wall of the whipper housing. The front wall preferably presents the form of a truncated cone tapering from the inlet to the peripheral edge of the front wall. The whipper housing also presents a peripheral side wall globally parallel to the drive shaft. This peripheral side wall globally presents the form of a cylinder. It surrounds the peripheral edge of the whipper. The whipper housing also comprises an outlet for evacuation of the milk reconstituted and whipped by the whipper. A conduit or nozzle can be attached to the outlet for dispensing in a container like a drinking cup.

[0056] Preferably, the whipper is disc shaped and the material surface of the radial front surface of the whipper is not smooth but rough. This roughness can be quantified by :

[0057] - an arithmetic maximum surface roughness (Sz) at least 200 pm, preferably at least 400 pm, even more preferably comprised between 400 and 750 pm.

[0058] - an arithmetic mean surface roughness (Sa) comprised of at least 30 pm, preferably at least 40 pm, even more preferably comprised between comprised between 40 and 100 pm.

[0059] This roughness increases the foaming a foamable beverages and in particular of hardly foamable beverage like plant-based milks.

[0060] In one preferred embodiment of this whipper, the rough surface of the radial front surface of the whipper presents a pattern, preferably a geometric pattern, said pattern being engraved on the surface of the radial front surface of the whipper.

[0061] In this embodiment, the radial front surface combines a continuous rough surface and a pattern engraved in the rough surface. Usually, the design of the pattern results from lines engraved in the rough surface and presenting largest pit depth than the pit of the continuous rough surface.

[0062] Preferably, the front surface of the whipper comprises grooves radially extending on said surface.

[0063] Usually, these grooves are equally distanced one from the other.

[0064] Preferably these grooves extend from the centre of the disc to the periphery of the disc and present a depth comprised between 1 and 2 mm and a width comprised between 2 and 6 mm. Preferably, these grooves present a smooth surface contrary to the front surface of the whipper that extends between the grooves and that is rough.

[0065] Independently from the type of whipper used in the mixing chamber, the whipper housing front wall can present bumps elevating from the surface of the front wall, the upper surface of each bump being flat and the edges of said upper surface being sharp. Such a whipper housing is similar to the housing described in WO 2013 / 149942. These bumps elevate from the whipper housing front wall surface that faces the front surface of the whipper. Then these bumps face the front surface of the whipper too. The upper surface of each bump - that is the most elevated part of the bump above the whipper housing front wall surface - is flat and the edges of said upper surface are sharp.

[0066] According to the preferred embodiment the outlet is positioned at the lowest position of the whipper housing front wall.

[0067] Preferably the bumps are regularly radially disposed on the whipper housing front wall around the whipper central axis, except in the area of the outlet. In particular it is preferred that the edges of both bumps surrounding the outlet are positioned at more than 2 mm from the edge of the outlet, preferably at more than 5 mm, even more preferably at a distance of 9 mm.

[0068] Preferably all the bumps present the same shape and the same size.

[0069] It is preferred that each bump extends along the whole radial length of the front wall. As the inlet for liquid in reconstitution usually corresponds to an axial opening in the whipper housing front wall it means that the bumps can radially extend on the front wall surface from the front wall opening corresponding to the inlet up to the peripheral edge of the front wall.

[0070] Preferably the upper surface of each bump is parallel to the front wall surface. Each bump appears like a local elevation of the front wall surface.

[0071] Preferably for each bump, its width is greater than its height.

[0072] According to the preferred embodiment, the bumps present the shape of a quadrilaterally- faced hexahedra solid, such as a trapezoidal solid, a cuboid or a cube. It has been noticed that such solids presenting a flat upper side, flat elevating faces and straight edges efficiently improved the formation of foam of quality. The bumps preferably present the shape of a cuboid that is a quadrilaterally-faced hexahedra solid composed of three pairs of rectangles.

[0073] The width and the number of bumps on the whipper housing front wall can vary. The sum of the surfaces of all the bumps is generally comprised between 20 and 75 % of the whipper housing front wall surface, preferably between 25 and 50 %, even more preferably between 30 and 40 %.

[0074] The front wall can comprise 3 to 1 1 bumps, preferably between 5 and 11 bumps, and according to the preferred embodiment 6 to 8 bumps.

[0075] The bumps can rise up between 0,5 and 2 mm above the front wall surface, preferably between 0,8 and 1 ,3 mm.

[0076] Preferably the whipper has a radial front surface with a shape substantially corresponding to the whipper housing front wall surface. The shear gap between the whipper radial front surface and the whipper housing front wall surface is preferably comprised between 0.4 and 1 .4 mm. Particular good results have been obtained for a mixing chamber such as described hereabove wherein :

[0077] - the beverage outlet is positioned at the lowest point of the whipper housing front wall surface, and

[0078] - the whipper housing front wall presents 6 to 8 bumps equally positioned on the front wall surface around the beverage outlet, and

[0079] - the seven bumps present the same cuboid shape, and

[0080] - the seven bumps rise up between 0,6 and 1 ,3 mm above the front wall surface, and

[0081] - the whipper is a disc presenting six grooves radially extending on its radial front surface, said grooves being equally distanced one from the other,

[0082] - the surfaces of the grooves are smooth,

[0083] - the surface of the whipper between the grooves is rough and presents an arithmetic maximum surface roughness (Sz) of at least 400 pm, and an arithmetic mean surface roughness (Sa) of at least 30 pm.

[0084] The whipper housing front wall of the mixing chamber presents a truncated cone shape tapering from a diameter of about 40 mm to about 31 mm and wherein the whipper presents a diameter of about 30 mm. Yet any other smaller or bigger mixing device presenting the same proportional ratio between the different diameters of the front wall truncated cone and the whipper are covered by the present invention.

[0085] Usually, the method is implemented in a beverage preparation apparatus that comprises a device to prepare a coffee liquid and the method comprises a step of mixing the milk based beverage with a coffee liquid to obtain a coffee-based beverage.

[0086] In order to obtain a coffee-based beverage, the beverage preparation apparatus can comprise at least one supply of roasted and ground coffee and a roasted and ground coffee extraction unit.

[0087] This supply can be a canister configured to store, dose and dispense a dose of roasted and ground coffee such as container comprising a dosing auger, a dosing screw or any powder dosing device.

[0088] Alternatively, this supply can comprise a container of roasted coffee beans configured to supply beans to a coffee grinder. The outlet of the grinder is positioned to feed roast and ground coffee to a roasted and ground coffee extraction unit. The apparatus can comprise different roasted and ground coffee canisters or beans containers storing different types of coffees (different by their origins, their roasting degrees, their blends, caffeine level ...) to offer various types of coffee beverages and even to enable the preparation of a coffee with a mixture of the different coffees. The extraction unit is configured to extract coffee from roasted and ground coffee with hot water and to dispense this coffee liquid in the same container as the milk based liquid.

[0089] Alternatively or in addition, the beverage preparation apparatus used in the method can comprise at least one supply of soluble coffee and a mixing chamber designed to reconstitute coffee liquid form said soluble coffee and to dispense this coffee liquid in the same container as the milk based liquid. This soluble or instant coffee can be a soluble powder or a coffee liquid concentrate. The apparatus can comprise several canisters to supply different types of soluble coffee.

[0090] In the present application :

[0091] - coffee-based beverage means a beverage comprising coffee and optionally additional components, like milk.

[0092] - chocolate-based beverage means a beverage comprising chocolate and optionally additional components, like milk.

[0093] - milk based liquid means a liquid comprising at least dairy milk and providing the same whitening function as dairy milk in the preparation of coffee-based beverages.

[0094] - concentrate means a liquid concentrate requiring a dilution with a diluent, preferably water, at the time of usage to form a beverage component.

[0095] - the term "back" in a mixing chamber refers to the parts of the mixing chamber positioned near the back wall supporting the whipper drive shaft,

[0096] - the term "front" in a mixing chamber refers to the parts of the mixing chamber positioned near the whipper housing beverage inlet,

[0097] - the terms "radial" and "axial" in a mixing chamber are defined in relation to the axis of rotation of the whipper.

[0098] Brief description of the drawings

[0099] The characteristics and advantages of the invention will be better understood in relation to the following figures :

[0100] - Figure 1 represents a part of a beverage preparation apparatus used to implement the method of the invention,

[0101] - Figure 2 represents a mixing chamber that can be used in the apparatus of Figure 1 ,

[0102] - Figures 3 and 4 are back and perspective views of the whipper housing of a preferred mixing chamber that can be used in the apparatus of Figure 2,

[0103] - Figures 5A and 5B illustrate preferred whippers that can be used in the mixing chamber in the apparatus of Figure 2,

[0104] - Figure 6 illustrates a beverage preparation apparatus to prepare coffee-based beverages with the method of the invention.

[0105] Detailed description of exemplary embodiments

[0106] With reference to Figure 1 the beverage preparation apparatus comprises a sub-assembly for preparing milk 100. This sub-assembly comprises two storing containers 9a, 9b providing supply of two different milk powders or concentrates : the first storing container 9a stores soluble dairy milk powder or concentrate while the second storing container 9b stores soluble plant-based milk powder or concentrate.

[0107] Each storing container 9a, 9b is connected to a respective dosing unit 7a, 7b able to provide powder doses to a common mixing chamber 1. According to another embodiment (not illustrated), the beverage preparation apparatus can comprise a single dosing unit connected to several different storing containers. The storing container can be a disposable tank like a cartridge, a can or tin, a pouch, ... or it can be a non-disposable canister that is refilled with powders.

[0108] The dosing units comprise means for dosing the powder or the concentrate. This means can be a dosing screw, a dosing auger, perforated discs for a powder and a pump or a peristaltic pump for a beverage concentrate. The dosing units are placed at the bottom of the storing containers to receive powder or concentrate therefrom by gravity.

[0109] The dose of powder or concentrate delivered from a dosing unit 7a, 7b falls in the mixing chamber 1 where it is mixed with a diluent, usually water, introduced from a water inlet 11 . This water inlet 11 is connected to a water supply system comprising a water tank 71 , a pump 72 and water heater 73. The mixture of powder or concentrate and water is mixed inside the mixing chamber 1 . The reconstituted beverage leaves the mixing chamber 1 through an outlet 12 that can be connected to an outlet tube and is delivered in a drinking cup 10.

[0110] The method of preparing a milk base liquid can be implemented within such a beverage preparation apparatus by :

[0111] - dosing dairy milk powder or concentrate from the first container 9a and preparing a first part of the final milk beverage with water inside the mixing chamber 1 and then dispensing said first part in the drinking cup 10, then

[0112] - dosing plant-based milk powder or concentrate from the second container 9b and preparing a second part of the final milk beverage with water inside the mixing chamber 1 and then dispensing said second part in the drinking cup 10.

[0113] In less preferred alternative method, the second part of plant-based milk can be prepared and dispensed before the first part of dairy milk. In an alternative beverage preparation machine (not illustrated), the sub-assembly for preparing milk can comprise two mixing chambers, each chamber cooperating with one dedicated storing container and its respective dosing device and being dedicated to the reconstitution of one type of reconstituted milk. Due to the difference of properties of dairy milk and plant-based milk powders or concentrates, specific reconstituting devices and conditions may be necessary for plant-based milk powder. For this reason, the beverage preparation machine can be provided with a dedicated mixing chamber for plant-based milk powders or concentrates.

[0114] When the sub-assembly for preparing milk 100 of the beverage preparation machine comprises one mixing chamber only as illustrated in Figure 1 , preferably, this mixing chamber 1 is designed for enabling the best reconstitution of plant-based milk.

[0115] Figure 2 is a more detailed view of a mixing chamber 1 susceptible to be implemented in the sub-assembly of Figure 1 . The mixing chamber comprises a dissolution chamber 6 designed to enable the contact of powder or concentrate with water and the dissolution or dilution of powder or concentrate. The dissolution or dilution is completed by whipping in the downstream part of the mixing chamber. Whipping can enable a foaming of the reconstituted liquid depending on the speed of rotation of the whipper.

[0116] The whipping function of the mixing chamber 1 comprises a whipper housing 2, a whipper 3 and a back wall 4. The whipper housing and the back wall forms a whipper chamber in which is lodged the whipper. The whipper 3 is attached to the drive shaft 81 of a motor 8 and the drive shaft is supported by the back wall 4. The whipper 3 presents a radial back surface 33 that faces the whipper housing back wall 4 and a radial front surface 32 opposed to the radial back surface. The whipper front surface 32 faces the outlet 61 of the dissolution chamber of the mixing chamber. The whipper housing comprises a front wall 21 (underlined by a dotted line). The front wall presents an opening 22 (see figure 3) corresponding to the outlet 61 of the dissolution chamber. The front wall 21 radially tapers from its peripheral edge to the edge of the opening 22 ; preferably the front wall presents the shape of a truncated cone. The whipper housing comprises a peripheral side wall that extends from the peripheral edge of the front wall and parallel to the axis XX'. The end of the peripheral side wall leans on the back wall 4 to close the mixing chamber. The inlet 1 1 of the whipper housing is attached to the beverage outlet 61 of the dissolution chamber. The whipper housing and the dissolution chamber can be made of one integral single piece of material.

[0117] Figures 3 and 4 illustrate a whipper housing 2 presenting the preferred features. The front wall 21 presents several bumps 5 elevating from its surface 21. The upper surface of each bump is parallel to the front wall surface so that each bump appears like a local elevation of the front wall surface.

[0118] All the bumps present the same shape of a cuboid with a flat top surface 51 and flat side surfaces with sharp edges between said different surfaces. For the best foaming function, the edges of the bumps must not be curved or smooth. All the bumps preferably present the same size. The bumps preferably extend from the whole axial length of the whipper housing front wall surface 211 that is from the opening 22 to the peripheral edge of the front wall. According to the invention no bump is present on the whipper housing peripheral side wall that is parallel to the axis XX'. For each bump, its width is greater than its height. Due to the small height of the bumps above the front wall surface 21 (between 0,5 and 2 mm, preferably between 0,8 and 1 ,3 mm), the bumps present the shape of rectangular plates elevating from the surface 21 of the whipper housing front wall. The outlet 12 of the whipper housing is positioned at the lowest part of the front wall and the bumps 5 are equally positioned on the front wall surface 21 around the outlet 12. Globally the sum of the surfaces of all the bumps is around 35 % of the whipper housing front wall surface. According to the preferred embodiment the two bumps surrounding the beverage outlet must not be directly adjacent to said outlet. Preferably these two bumps are positioned at a distance d of at least 2 mm, preferably at least 5 mm, from the beverage outlet. The outlet 12 of the whipper housing comprises a tube that is slightly oriented downwards to help for the evacuation of the beverage.

[0119] Figures 5A and 5B illustrate whippers 3 that are preferably used with the mixing chamber dedicated to the reconstitution and foaming of plant-based milk part and in particular with the whipper housing of Figures 3 and 4. The whipper is a disc presenting a diameter of 31 mm and of which front face 32 comprises six grooves 31 . These grooves are equally distanced one from the other. Preferably these grooves extend from the centre of the disc to the periphery of the disc and present a depth comprised between 1 and 2 mm and a width comprised between 2 and 6 mm. The surface of these grooves is smooth.

[0120] In the whipper of Figure 5A, the surface of the radial front surface 32 of the whipper is rough except the surfaces of these grooves are smooth.

[0121] In the whipper of Figure 5B, except the surfaces of these groove, the surface of the radial front surface 32 of the whipper is rough and in addition presents a geometrical pattern (snake skin type).

[0122] Both whippers are made of plastic and were produced by injection moulding. A part of the surface of the mould was texturized to provide the final rough surface and. the geometrical pattern, Texturization of the mould was obtained by laser surface texturing. Yet other process can be used like chemical etching. For both whippers the surface roughness of the radial front surface 32 between two grooves 32 (as illustrated by the surface A1 in Figure 5B) was analysed with a non-contact roughness meter system Keyence VR5200 3D Profilometer.

[0123] The whipper of Figure 5A showed :

[0124] - an arithmetic mean surface roughness Sa of 37 pm, and

[0125] - an arithmetic maximum surface roughness Sz 220 pm.

[0126] The whipper of Figure 5B showed :

[0127] - an arithmetic mean surface roughness Sa of 85 pm, and

[0128] - an arithmetic maximum surface roughness Sz 740 pm.

[0129] Figure 6 illustrates a beverage preparation machine enabling the preparation of a coffee based beverage. The machine comprises a sub-assembly 100 of a beverage preparation machine for preparing a milk based beverage such as illustrated in Figure 1 and a subassembly 101 of a beverage preparation machine for preparing a coffee.

[0130] Each sub-assembly can prepare a part of the final coffee-based beverage comprising coffee and milk. Milk based beverage and coffee are dispensed in the cup 10 to produce the final coffee-based beverage. mixing chamber 1 water inlet 11 outlet 12 whipper housing 2 front wall 21

[0131] 22 whipper 3 groove 31 front surface 32 back surface 33 hole 34 back wall 4 bump 5 upper surface 51 edge 52 dissolution chamber 6 outlet 61 water tank 71 pump 72 heater 73 motor 8 drive shaft 81 storing container 9a, 9b dosing unit 91a, 91b drinking cup 10 sub-assembly for preparing milk 100 sub-assembly for preparing coffee 101

Claims

1. A method for producing a milk-based liquid using a device (100, 101) for preparing a beverage, said device including at least one source of instant dry or concentrated plant milk, at least one source of soluble dry or concentrated milk of animal origin, water supply system, at least one mixing chamber (1) configured to produce a liquid by receiving and mixing a portion of the soluble powder or concentrate with water and by dispensing the reconstituted liquid, wherein the method includes the steps obtaining a first portion of a milk-based liquid by feeding into the mixing chamber a portion of soluble dry or concentrated milk of animal origin and water for reconstituting milk of animal origin and dispensing said first portion obtained from milk of animal origin, and obtaining the second part of the milk-based liquid by feeding a portion of soluble dry or concentrated plant milk and water into the mixing chamber to reconstitute the plant milk and dispensing the second part obtained from the plant milk, wherein the first and second parts of the milk-based liquid are mixed with each other to obtain the finished milk-based liquid.

2. The method according to claim 1, wherein the first portion of the milk-based liquid constitutes from 30 to 70% by volume of the finished milk-based liquid, preferably from 50 to 70% by volume.

3. The method according to paragraph 1 or 2, in which in the first stage, the first part of the milk-based liquid is obtained and poured into a container (10), and In the second stage, the second part of the milk-based liquid is obtained and poured into the same container (10).

4. The method according to the preceding paragraph, in which in the first stage the first part is foamed.

5. The method according to any of the preceding paragraphs, wherein the beverage preparation device includes at least two mixing chambers, and wherein one first mixing chamber is designed with the possibility of being filled from a source of soluble dry milk of animal origin and is intended for reconstituting the first portion of the milk-based liquid, and wherein one second chamber is designed with the possibility of being filled from a source of soluble dry vegetable milk and is intended for reconstituting the second part of the milk-based liquid.

6. The method according to the preceding claim, wherein the cooking stages in the first and second chambers are started sequentially.

7. A method according to any of the preceding claims, wherein at least one of the mixing chamber (1) of the beverage preparation device comprises: a dissolution chamber (6) comprising an inlet for powder or concentrate, a water supply nozzle (11) and an outlet (61) for reconstituted milk liquid, a whipping apparatus unit, wherein said whipping apparatus unit includes a housing (2), a whipping apparatus (3) and a back wall (4), wherein: the body of the whipping apparatus and the back wall form the chamber of the whipping apparatus, and the whipping apparatus is placed in the whipping apparatus chamber, and the body of the whipping apparatus includes an inlet, wherein said inlet is connected to the outlet (61) of the dissolving chamber, and the outlet (12) for the beverage, and the whipping apparatus includes a drive shaft (81) for driving the whipping apparatus, said drive shaft being supported by a rear wall, and the whipping apparatus has a radial rear surface (33), wherein said radial rear surface faces the rear wall (4) of the housing of the whipping apparatus, and a radial front surface (32) opposite the radial rear surface, and the body of the whipping apparatus comprises a front wall (21), wherein said front wall faces the radial front surface (32) of the whipping apparatus.

8. The method according to the preceding paragraph, wherein the whipping apparatus (3) has a disc-shaped form, and at least a portion of the surface of the radial front surface (32) of the whipping apparatus is rough and has a maximum arithmetic roughness (Sz) of the surface of at least 200 μm, preferably at least 400 μm.

9. The method according to claim 7 or 8, wherein in at least one of the mixing chambers (1) of the beverage preparation device, the front wall (21) of the housing of the whipping apparatus has bulges (5) rising from the surface (211) of the front wall, and the upper surface (51) of each bulge is flat, and the edges (52) of said upper surface are sharp.

10. The method according to any of the preceding claims, wherein the beverage preparation device includes a sub-unit (101) for preparing a coffee or chocolate liquid, and said method includes the step of mixing a milk-based beverage with a coffee or chocolate liquid to obtain a coffee beverage or a chocolate beverage.