WO2004100739A1

WO2004100739A1 - Method and device to generate foam in hot beverages

Info

Publication number: WO2004100739A1
Application number: PCT/BE2003/000219
Authority: WO
Inventors: Alain Hoorelbeke
Original assignee: Alain Hoorelbeke
Priority date: 2003-05-16
Filing date: 2003-12-12
Publication date: 2004-11-25
Also published as: BE1015518A4; AU2003289770A1

Abstract

Method and device for the generation of a foam layer during the preparation of hot beverages by using a dispensing system through which fine extracted liquid jets impinge against each other under an angle to fall directly in a cup. A device to obtain the objective which is provided with a least two spray nozzle heads (4), set under an angle, opposite and in front of each other or an apertured spray mouth (6) wherein the jets are impinging under an angle of 120 to 180° and under a pressure of 1,4 to 1,8 Bar.

Description

Method and device to generate foam in hot beverages.

The invention concerns the preparation of hot beverages, like coffee, chocolate milk,... and more particularly the generation of a foam layer on such a liquid surface. The invention concerns especially a method and a device to create a foam layer. The preparation of coffee by rising a fluid in a column using the pressure generated in a liquid tank or by using a pump mechanism is well known. Our invention targets the foam making during the coffee preparation, but is obviously not limited to only coffee. Several methods are already developed to reach the same objective. The patent NL1006039C deals with a device, provided with a heating element, to create a pressure in a water tank to rise a liquid in a pipe through a coffee layer. The foam layer in this patent is made by using a temporary reservoir wherein the coffee extract is injected, directly or by using an intermediate buffer reservoir, on the surface of the liquid. This additional buffer reservoir has the disadvantage that always a part of residue is left and supplementary precautions are needed to evacuate the residue. A braking effect of this buffer reservoir on the outflow is another disadvantage. In the state of the art, it is also known to spray coffee downwards on a rough bottom surface according to the patent NL1016106C. The impinging effect with the rough surface creates turbulence, which leads to foam generation. The surface has to be treated to obtain the uneven bottom structure. According to patent GB601683, filed in 1945, a way to inhibit and eliminate foaming during fermentation is explained. Liquid is sprayed on a concave surface to inhibit the foaming and this because of two reasons. The first one is that gas can escape in the fine liquid spray. Secondly, against the wall the foam will be destroyed.

This invention targets a simplified method and a device to generate a foam layer by spraying fine liquid flows against each other and more particularly coffee extracts, characterised in that the flows are impinging under an angle. In the state of the art it is known to mix liquids by spraying them against each other under an angle. The Belgian patent BE452812 from 1943 describes a device to produce an aerosol by orienting three liquid jets to impinge on each other. A patent application US2002128416, titled "continuous free impinging jet micromixing" published in 2002, describes a process by micro mixing polymers, to guide the jets for impinging on each other under an angle. US5011293 deals with an apparatus to mix two flows of emulsions, impinging on each other and a concave wall.

In the prior art, is not known to generate foam by jetting fine liquid flows to each other and more particularly in the field of coffee preparation or any other hot beverage. We believe to be novel and inventive. We do not need additional aids, like buffers or impinging surfaces, to generate foam and this is a first advantage. Secondly, the coffee extract and its foamed layer are guided directly to the cup, which obviously is a more rapid method.

Finally, a third advantage is that we do not need a high pressure-generating device to obtain our goal. A detailed description of the mechanism will be explained by two examples. By using the following drawings we will explain the invention, but it is obvious for the skilled person that the invention is not limited to these two examples and that the scope of the patent application is much broader in the spirit of this invention.

Fig. 1 : a device with multiple spray nozzles heads like example 1

Fig. 2 : a device with a single spray mouth like example 2

Fig. 3 : detail of the spray nozzle

Fig. 4 : Graphic about foam generation

A first example consists of at least two fine liquid jets, preferably coffee extracts, impinging against each other under an angle, by setting opposite spray nozzles in front of each other under an angle. A pressure (ΔP) will be generated in a reservoir (1) by heating a liquid (ΔT) to rise a liquid through a coffee layer (2). A holder, as known in the state of the art can be used. The invention deals with hot beverages and is consequently not limited to just coffee, but also chocolate milk could be involved. To use a pump mechanism for displacing the liquid is another possible solution in the scope of this invention. At the end of the column (3) the duct divides, called dispensing, depending on the number of spray nozzle heads (4). The coffee extract flows are divided over at least two spraying nozzles. It is obvious that the number of spraying nozzles is variable to reach a satisfying result. Preferably, four spraying nozzles are oriented to each other. The generation of a certain pressure to target a satisfying spray result through the nozzle heads (5) will be of a great importance. Experimentally, we found that the spraying nozzle heads should be oriented at an angle of 180°. According to figure 4, a satisfying result will be already obtained by setting them under an angle of 120°. These settings combined with a pressure of 1,6 Bar will generate the best foam layer. Nevertheless, a pressure between 1,4 and 1,8 Bar also leads to satisfying results. The temperature is a last parameter that we found and considered as an important element during our experimental work to create a foam layer. We became a durable foam layer at 60° C. A too high or a too low temperature will be influencing the foam layer negatively. Consequently, we prefer a temperature interval between 45 and 75° C. According to figure 4 we illustrate a graphical presentation of our experimental results, by varying the pressure and the angular position of the spray nozzles in relation to foamed layer. This allows us to determine an interval wherein the best results appear.

A second example, according to figure 2 consists of a spray mouth (6) to fit in the apparatus. The spray mouth is concentrically provided with multiple spray apertures (7) and in such a way that the fine liquid sprays through the apertures on each other under an angle β. Referring to the previous example, the angle β is preferably 180 °. The spray mouth is preferably provided with screw thread to fit it. It is obvious for the skilled man that other fittings could be used. According to the figures 3a and 3b, several examples of spray mouths are illustrated.

The method and an adapted device, are applied to create an impinging effect between extracted liquid flows without the use of additional aids, known in the state of the art. It is obvious that the foam generation according to preceding description is different compared to the state of the art.

Claims

Claims :

1. Method for the generation of a foam layer during the preparation of hot beverages and characterised in that the extracted liquid is sprayed through a dispensing system for the creation of fine flows and in such a way that a least two jets impinge on each other.

2. Method for the generation of a foam layer during the preparation of hot beverages according to claim 1 and characterised in that the fine liquid sprays impinge under an angle between 120 and 180 °.

3. Method for the generation of a foam layer during the preparation of hot beverages according to the preceding claims and characterised in that the liquid sprays impinge under a pressure of 1,4 to 1,8 Bar.

4. Method for the generation of a foam layer during the preparation of hot beverages according to the preceding claims and characterised in that the liquid sprays have a temperature of 45 to 75° C.

5. Device for the generation of a foam layer during the preparation of hot beverages provided with a water tank, a column, a coffee layer, a pressure generator, a dispenser and characterised in that the extracted liquid sprays impinge against each other through the dispenser.

6. Device for the generation of a foam layer during the preparation of hot beverages according to claim 5 and characterised in that the dispenser is provided with at least two spray nozzle heads, set under an angle opposite and in front of each other.

7. Device for the generation of a foam layer during the preparation of hot beverages according to claim 5 and characterised in that the dispenser consists of a spray mouth, provided with apertures through which the jets impinge on each other.

8. Device for the generation of a foam layer during the preparation of hot beverages according to claim 7 and characterised in that the apertures are concentrically provided in the spray mouth.

9. Device for the generation of a foam layer during the preparation of hot beverages according to claims 7 or 8 and characterised in that the spray mouth is provided with screw thread to fit it in the apparatus.

lO.Device for the generation of a foam layer during the preparation of hot beverages according to in claim 1 to 4 related method.