WO2004107939A1

WO2004107939A1 - Method of preparing a coffee drink and an apparatus for performing the method

Info

Publication number: WO2004107939A1
Application number: PCT/CZ2004/000030
Authority: WO
Inventors: Miroslav HUBÁCEK
Original assignee: Hubacek Miroslav
Priority date: 2003-06-05
Filing date: 2004-05-31
Publication date: 2004-12-16
Also published as: CZ20031568A3

Abstract

According to a method of preparation of a coffee drink, a dose of coffee is extracted in water under certain pressure and after finishing the extraction, the coffee product obtained by the extraction is led through a pressure element by the effect of increasing the pressure acting on the coffee product at the inlet side of the pressure element to value that is higher than value of pressure during the extraction and higher than value of pressure at the outlet side of the pressure element, and the coffee product is thus pushed through the pressure element. An apparatus for preparation of coffee drink comprises a vessel (5, 13), in which a dose of coffee to be extracted is placed, a feed (2) for supplying water to coffee to be extracted, and filter means placed in the vessel (5, 13) for filtering coffee product obtained by extraction. The apparatus further comprises a pressure element positioned at the outlet from the vessel (5, 13) for leading the coffee drink out of the vessel (5, 13) under a discharge pressure that is higher than pressure under which extraction takes place and higher than pressure at the outlet side of the pressure element, and a pressurizing means to increase pressure inside the vessel (5, 13) to the value of the discharge pressure.

Description

METHOD OF PREPARING A COFFEE DRINK AND AN APPARATUS FOR PERFORMING THE METHOD

The present invention relates to method of preparing a coffee drink and an apparatus (coffee maker) for performing the method.

There are known several methods of preparing a coffee. The significant property of coffee is that it can be prepared by many methods, where each method has its own advantages and in turn its deficiencies.

One of the methods of preparing coffee is method of preparing an Italian espresso (hereinafter referred to as "espresso") . In order to prepare an espresso, a coffee with a lower acid content is recommended to be used. If coffee is duly prepared by this method, the espresso distinguishes itself by a little bitterish taste which is fading long time. The method itself is performed so that exactly determined amount of water heated to about 90°C is pushed under pressure of 9 bar through ground coffee. Process during this method is determined by number of factors. These factors are e.g. pressure of hot water, temperature of water, amount of coffee in pressure head, period during which coffee is pressured, coarseness of grinding of coffee, a force with which coffee is pressed in the pressure head, kind of ground coffee etc. The goal of the process is to push also the so-called crema (cream) through the pressed coffee in the pressure head (gruppa) . Crema (cream) is a froth cap comprising the most important volatile aromatic and taste (flavour) substances (about 600 essences) which make coffee a coffee. However, only a few kinds of coffee do not get bitter or sour during this process, and in the case the exact procedure is not observed, coffee will loose its characteristic taste and aroma or it does not have any. If coffee is too coarse, drink jetting from coffee maker is thin and watery, if, in turn, coffee is too fine-ground, drink is dripping only slowly from the coffee maker and is bitter.

Another method is preparation of so-called drip coffee. Hot water is let slowly drip through filter, in which coffee is placed. This method is used mainly in businesses, where coffee is to be further heated for a longer period in pots. Generally, coffee gets bitter during further additional heating; coffee prepared in this way into pots has to be relatively very weak (it does not include important aromatic and taste essences) . This is achieved mainly by letting coffee drip through filter which retains these highly volatile substances. Another disadvantage is that coffee drips irregularly and it happens that coffee is less "extracted" at the edges, in no case, however, the so-called crema (cream) is extracted. The cream remains as a froth cup in the filter in the exhausted coffee. Again, it holds true that for this method of coffee preparation coffee is ground to a particular coarseness and that not all kinds of coffee are suitable for this method of coffee preparation.

Another method is preparing the so-called Turkish coffee by reboiling in Turkish coffee-pot. The disadvantage of this method is mainly the fact that coffee, if subject to hot water for a longer period, especially when water temperature is close to boiling point, releases another components such as different kinds of acids which are already relatively aggressive, irritate coat of the stomach, and contribute to bitter after-taste of coffee (boiling impairs taste of coffee since it removes volatile aromatic substances and accentuates bitter substances) . In order to lower this bitter aftertaste, cardamom is favorably added to coffee prepared in this way in the Arab world. The characteristic taste of cardamom would override the bitterness. Unless relatively coarsely ground coffee is used for this method of preparing coffee and coffee is rather promptly consumed, coffee gets unfit to drink.

One of the other methods may be the so-called cafetiere. It is a method wherein coffee is put into pre-heated pot, then hot water is poured on coffee, coffee is covered by lid with a piston screen and let get extracted. After approx. 4-minute still standing filter with screen is pressed downwards and coffee-grounds are separated from coffee drink. The advantage of this method is that it is possible to prepare arbitrary amount of coffee of good taste, the disadvantage is that by pressing the filter also major part of froth is pressed and also the fact that coffee gets rather rapidly cool in glass pot.

Coffee maker-percolator was disclosed in 1827 in France. Percolator is favoured especially in United States. It fills the room with excellent coffee aroma. However, coffee is boiled in percolator and its taste is bitter.

Finally, the last method is preparation of so-called instant coffee. This industrial method resembles the most household method of preparing coffee through filter, wherein resulting extracted drink is further deprived of water and dried into small crystals or granules. From the point of achieved coffee taste it is necessary to mention also the reasons for which coffee is roasted. In raw state, coffee keeps quality for even number of years, however, when deprived of peel and roasted, it remains fresh for about 14 days. By roasting all taste components intensify and amount of gases releases, which gases then fill coffee with inimitable aroma. These gases are so fine that they are capable of rising through pore in one's skin and it is known that consumer of fresh coffee is sweet of the coffee. During exactly determined roasting process chemical reactions occur due to high temperatures, wherein starch changes into sugar, several kinds of acids originate, whereas other acids degrade. The original cell structure of coffee beans dismantles. Protein decomposes into peptides which liberate as oils. Aromatic oils called also coffee essence or coffee oil are volatile carriers of typical aromatic and taste substances of coffee, and since they are water-soluble, they make themselves felt significantly in coffee brew. During extraction process these oils release and fill together with releasing oxide the cream (crema) .

Nowadays the most used method of preparing coffee is the method of preparing espresso which is also the most demanding and most costly method.

The object of the present invention is to remove the above mentioned disadvantages of individual methods of preparing coffee by proposing new method and apparatus for preparing coffee drink, result of which method and apparatus a coffee drink - coffee with fully developed aroma and full taste, from any quantity of provided coffee which is of any coarseness of grinding and of any variety, is prepared, the preparation being automatic so that in a repeated preparation of coffee all aromatic and taste essences comprised in coffee are retained.

The object of the method and apparatus (coffee maker) is to retain all ethereal and volatile water-soluble substances comprised in vapours and caught in form of a froth - the crema and to deliver all these pure essences being without any negative taste or scent traces which otherwise originate during scalding or reboiling of coffee to an arranged pot.

Another object of the invention is to propose such method and apparatus for preparing coffee, by means of which it is possible to achieve always the same taste properties of coffee independent of its variety, type, quantity and consistency. At the same time the apparatus would enable to achieve any number of taste variants by choosing variables. The taste variants could^' be repeatedly obtained by means of setting the variables. It would be possible to use even such varieties of fine Arabian coffees that cannot be processed by present automatic coffee makers, and also it would be possible to use extra strongly roasted coffees without letting them turned sour or otherwise deteriorated by the preparation.

The object of new inventive method of preparing coffee is to combine advantages following from different methods of preparing coffee according to the prior art and to remove disadvantages linked to these methods which unfavourably affect final quality of coffee drink. More general purpose is to put together two relatively different groups of consumers of coffee: 1. group of coffeehouse consumers who got used to speed with which classical espresso is prepared and favour also the fragrant crema of espresso, and

2. group of coffee gourmets preferring extracted coffee drink with all its fullness and taste nuances.

If the proposed solution is embodied in the form of coffeehouse or household automatic coffee maker, it will be possible to give the gourmet relish of group 2. also to an ordinary consumer and to replace a simple consumption by a new culture of coffee drinking, a culture which could be similar to e.g. culture of drinking table wines.

The above mentioned objects are achieved by method of preparation of a coffee drink according to the present invention, wherein an overall amount of coffee (a dose) to be extracted is provided, then the dose of coffee is extracted in water under certain pressure, the substance of the method consisting in that after finishing extraction of the dose of coffee the coffee product obtained by the extraction is led through a pressure element by the effect of increasing the pressure acting on the coffee product at the inlet side of the pressure element to value that is higher than value of pressure during the extraction and higher than value of pressure at the outlet side of the pressure element, the coffee product being by this manner pushed through the pressure element.

Along with increasing the pressure acting on the coffee product it is advantageous to decrease pressure at the outlet side of the pressure element. The substance of an alternative method of preparation of a coffee drink, wherein an overall amount (a dose) of coffee to be extracted is provided, then the dose of coffee is extracted in water under certain pressure, consists in that after finishing extraction of the dose of coffee the coffee product obtained by the extraction is led through a pressure element by the effect of decreasing pressure at the outlet side of the pressure element to value that is lower than value of pressure acting on the coffee product obtained by the extraction at the inlet side of the pressure element.

Advantageously, along with decreasing the pressure at the outlet side of the pressure element the pressure acting on the coffee product obtained by the extraction at the inlet side of the pressure element is increased.

Preferably, coffee is extracted under water temperature raging from 60°C to 75°C and under pressure from 1 bar to 5 bar. Preferably, the coffee product is led through the pressure element by the effect of difference of pressures at the inlet side of the pressure element and the outlet side of the pressure element being of value 5 bar to 15 bar.

The coffee product obtained by the extraction my be at the same time filtrated during the extraction of coffee. After the filtration, upon finishing of the extraction, an additional extraction my follow.

Alternatively, the coffee product obtained by the extraction is filtrated only after finishing extraction of the dose of coffee before leading the coffee product through the pressure element . An additional component may by introduced into the coffee product obtained by the extraction, which component is led along with the coffee product through the pressure element.

Alternatively, the additional component may be introduced into the coffee product only after the product is led through the pressure element.

Advantageously, the additional component includes aromatic or flavour essences or it may include C0₂ and/or N₂0.

As the pressure element a pressure valve my be used with advantage.

The coffee product obtained by the extraction my be led through the pressure element into a container which is e.g. vacuum thermo-container.

In order to obtain coffee drink of a desired specific flavour or quality, advantageously a variable, combination of variables or all variables influencing final flavour of coffee drink are set to desired concrete values. The variables are e.g. variety, quality, coarseness of grinding of coffee, period of extraction, temperature of extraction, pressure of water during extraction, pressure at the inlet side of the pressure element during leading the coffee product obtained by the extraction through the pressure element, pressure at the outlet side of the pressure element, proportion of ground coffee amount to amount of water in which coffee is extracted.

The above mentioned parameters my be advantageously chosen as follows: for the extraction - use of dose of 7 grams for 125 ml of water (for two cups 15 g for 250 ml) under temperature near to 65°C, duration of extraction period about 3 minutes and repressurizing of mixture C0₂ and N₂0 to pressure close to 5 bar. After pressurizing by the increased pressure of 15 bar the mixture is led through the pressure element.

Another possible advantageous setting of parameters may be the following: for the extraction - use of dose of 7 grams for 100 ml of water (for two cups 15 g for 200 ml) under temperature near to 70°C, duration of extraction period about 4 minutes and repressurizing N₂0 to pressure close to 5 bar. After pressurizing by the increased pressure of 12 bar the mixture is led through the pressure element.

The substance of an apparatus for preparation of a coffee drink, comprising a vessel, in which a dose (an overall amount) of coffee to be extracted is placed, a feed for supplying water to the coffee to be extracted, and filter means placed in the vessel for filtering coffee product obtained by the extraction, consists in that the apparatus further comprises a pressure element positioned at the outlet from the vessel for leading the coffee drink out of the vessel under a discharge pressure that is higher than pressure under which extraction takes place and higher than pressure at the outlet side of the pressure element, and pressurizing means to increase pressure inside the vessel to the value of the discharge pressure.

The apparatus comprises with advantage also underpressure means to decrease pressure at the outlet side of the pressure element along with increasing pressure inside the vessel by the pressurizing means. The substance of an alternative apparatus for preparation of coffee drink, comprising a vessel, where a dose (an overall amount) of coffee to be extracted is placed, a feed for supplying water to the coffee to be extracted, and filter means placed in the vessel for filtering coffee product obtained by the extraction, consists in that the apparatus further comprises a pressure element positioned at the outlet from the vessel for leading the coffee drink out of the vessel under a discharge pressure that is higher than pressure at the outlet side of the pressure element, and underpressure means to decrease pressure at the outlet side of the pressure element.

The apparatus comprises with advantage pressurizing means to increase pressure inside the vessel to the value of the discharge pressure at the time when pressure at the outlet side of the pressure element is decreased by the underpressure means .

The pressurizing means may be e.g. a lower part positioned in the lower portion of the vessel. The lower part is slidable to increase pressure in the vessel to the discharging pressure and adapted to accommodate the dose of coffee to be extracted.

Another possibility is that the pressurizing means is in the form of a pressure feed for supplying a pressure medium into the vessel. The pressure medium may include an additional component comprising e.g. aromatic or flavour essences or carbon dioxide.

The filter means may be e.g. filter provided with a draw bar for sliding movement of the filter inside the vessel to facilitate removal of coffee-grounds from the vessel. The pressure element may be e.g. a pressure valve.

Advantageously, the apparatus includes at the outlet side of the pressure element a container to receive the coffee drink. The container may be airtight connected to the outlet side of the pressure element and provided with underpressure means for decreasing pressure in the container. The underpressure means to decrease pressure in the container may be a pressure hose connected to a device for pumping air from the container.

The container is preferably a vacuum thermocontainer for keeping temperature of coffee drink.

The container may be provided with a discharge nozzle placed at the bottom of container. Further it can be provided with insulating layer and a heating device.

Again, the pressure element may advantageously be a pressure valve.

Thus, the above mentioned method according to the present invention differs essentially from the prior art in that the prior art methods for preparation of espresso use rather fast extraction that takes place directly under increased pressure (10 bar to 15 bar), when hot water is pushed through coffee and filter under the effect of a high pressure. Under the effect of the high pressure it is not possible to avoid release of some undesirable admixtures into originated coffee drink, which admixtures deteriorate quality of coffee drink. Using the method according to the present invention, however, first - extraction takes place and thereafter, when an overall amount (dose) of coffee has already been extracted, product of the extraction is led through the pressure element by the effect of the difference of pressures at the inlet and outlet sides of the pressure element. Only after pushing through the pressure element a coffee drink to be consumed is produced. Passing the coffee product through the pressure element can be achieved for instance by pushing the coffee product obtained by the extraction through the pressure element under an increased pressure (10 bar to 15 bar in the case of espresso) . Another possibility how to pass the coffee product through the pressure element is to decrease pressure at the outlet side of the pressure element to value that is lower than pressure at the inlet side of the pressure element.

There are also disclosed methods of preparation of another coffee drinks that differ from espresso in the prior art, during which methods firstly extraction takes place. By the extraction however, coffee drink directly originates and it is then delivered (released from the coffee maker in fact) under substantially not increased pressure for consumption. The method according to the present invention differs essentially from the prior art methods in that the coffee drink originates only by pushing the coffee product obtained by the extraction through the pressure element under an increased pressure, which renders it quite different flavour characteristics.

Coffee product obtained by extraction can be filtered directly during the extraction - for instance coffee to be extracted is placed in a screen. Other possibility is that coffee product obtained by extraction is filtered only after finishing extraction of an overall amount of coffee (the dose of coffee) but before leading the coffee product through the pressure element while producing a coffee drink to be consumed.

It is also possible to enrich the coffee product obtained by the extraction with an additional component, for instance aromatic or flavour essences or carbon dioxide, which is then along with the coffee product led through pressure element while producing a coffee drink to be consumed.

Preferred embodiments of the present invention will now be described hereinafter by way of example only with reference to the accompanying drawings, in which:

Figure 1 illustrates schematically first embodiment of an apparatus for performing method according to the present invention, comprising pressurizing means;

Figure 2 illustrates schematically second embodiment of an apparatus for performing method according to the present invention, comprising pressurizing means; and

Figure 3 illustrates schematically third embodiment of an apparatus for performing method according to the present invention, comprising an underpressure means and pressurizing means .

Figure 1 illustrates schematically first embodiment of an apparatus for performing method according to the present invention. The apparatus comprises feed 2 for supplying water through single-way valve 1 into vessel 5 through lid 3. Amount, temperature and pressure of water are adjustable. The lower part of vessel 5 comprises a movable part 6 including dose of coffee to be extracted. After supplying water into the vessel 5, extraction of coffee in vessel 5 takes place. After finishing the extraction of coffee, pressure in vessel 5 is increased by moving part 6 upwards in vessel 5 and coffee product obtained by the extraction is pushed through filter 4, causing formation of coffee mixture, into a pressure hose 7. The coffee mixture leaves the pressure house 7 and enters provided coffee cup. To facilitate cleaning of vessel 5 filter 4 can be arranged slidably in downwards direction to remove coffee-grounds from vessel 5.

Figure 2 illustrates schematically second embodiment of an apparatus for performing method according to the present invention. An overall amount (a dose) of coffee to be extracted is poured in screen 14. Screen 14 is inserted into a pressure vessel 13 which is closed with lid 12. A feed of hot water through singe-way pressure valve 11 is mounted in lid 12. Supplying hot water into screen 14 coffee is extracted and coffee product obtained by the extraction collects at the bottom of pressure vessel 13. After finishing the extraction, all the obtained components are mixed as a result of their pressing caused by pressure of a pressure medium which is supplied into the vessel 13 through a pressure feed 16. By the effect of pressure of the pressure medium the mixed components are pushed through pressure valve 15 and discharge nozzle, producing a coffee drink suitable for consumption, and led e.g. to coffee cup.

Vessel 13 retains all the extracted substances obtained by extraction of coffee - flavour essences and aromatic acids saturated in froth and extracted coffee. All these ingredients are kept in vessel 13 hot and ready to be pressurized and pushed through pressure valve 15.

Apparatus which is schematically depicted in fig. 2 operates with number of parameters which may by controlled in order to influence e.g. resulting flavour properties of the obtained coffee drink or its composition. The parameters that may be controlled are for instance temperature, amount and pressure of water supplied to screen 14, coffee extraction period, amount, sort, grain size and other properties of coffee to be extracted, temperature, amount, pressure and other properties of pressure medium supplied to vessel 13 etc. The resulting coffee taste can be influenced by addition of aromatic and flavour essences into the pressure medium. For instance by adding carbon dioxide fullness of coffee can be increased, flavour of cardamom will be appreciated by people in the Arab world or a nutty or vanilla flavour can be favored by people from the north Africa.

After performing small amendments, apparatus schematically illustrated in fig. 2 can be adapted to use in current automatic coffee machines, where it could for example replace head of classic pressure machine - the so called gruppa.

Apparatuses depicted in fig. 1 and 2 include an overpressure means which is, in the case of figure 1, a movable part 6 and, in the case of figure 2, a pressure feed 16 with pressure medium delivered through the feed 16. The overpressure means generally serves to increase pressure acting on coffee product obtained by extraction, after the extraction of the whole amount (a dose) of coffee to be extracted is completed, to the value generally higher than value of pressure during the extraction and also higher than vaiue of pressure acting at the outlet side of pressure element. The pressure element may be for example pressure valve 8, 15. As a result, the coffee product is pushed through the pressure element, which render the obtained coffee drink specific taste characteristics and quality.

If there is a need to prepare a larger amount of coffee drink, it is possible to extract more coffee and to lead the coffee product obtained by extraction through pressure element into vacuum thermo-container. This solution can be used with advantage e.g. in canteens or other facilities, where there is a need to serve a larger amount of a prepared drink in short time period. This way, it could be possible to retain taste characteristics of the extracted drink unchanged for a longer time. This is because the taste of coffee considerably deteriorates by an additional heating and oxidation.

Alternatively, coffee product obtained by extraction can be led through pressure element by decreasing pressure at the outlet side of the pressure element. This solution is illustrated schematically in fig. 3 which depicts an underpressure means to decrease the pressure. In the embodiment illustrated in fig. 3 the underpressure means is pressure hose 18 and vessel 19, from which air is partially pumped off through the pressure hose 18. Thus, an underpressure means generally serves to create a relative underpressure at the outlet side of pressure element with respect to pressure at its inlet side.

In apparatus in figure 3 which, similarly as in the case of apparatus illustrated in fig. 2, comprises valves 17, 15, lid 12, vessel 13, screen 14 and pressure feed 16, coffee is prepared to pressure vacuum vessel 19 which is provided with insulating thermo-layer 20. Air is pumped off from the vessel 19 through pressure hose 18. It is obvious that such a decreasing pressure can be combined with simultaneous increasing pressure acting at the inlet side of pressure element. One of possible variants of such solution is schematically illustrated in fig. 3, where the apparatus includes both the underpressure and the pressure means. The apparatus from fig. 3 includes also vacuum thermo-container for preparation of a large quantity of coffee drink as discussed above. . By combining the relative underpressure created in this way at the outlet side of valve 15 and relative overpressure created by feeding pressure medium through pressure feed 16 into the room of vessel 13, which could also be called pressure head, a desired pressure difference at the both sides of valve 15 is achieved, which pressure difference is needed to lead the coffee product through valve 15, while creating the coffee drink. Thus, a higher effect in second phase of preparation of drink is achieved. The absence of oxygen in pressure thermo-vessel 19 decreases the process of oxidation of the already prepared drink and prolongs period, during which drink taste remains unchanged. In order to keep temperature of the prepared drink, it is alternatively possible to build heating device 22 in the thermo-casing.

All the above described solutions have in common the fact that coffee product obtained by extraction is led through pressure element by the effect of difference of pressure acting at the inlet side and pressure at the outlet side of the pressure element, wherein the pressure at the inlet side is always higher than pressure at the outlet side of the pressure element. The essential feature is that in first step a complete operation of extraction takes place and only after its finishing the coffee product obtained by the extraction is led through the pressure element. The pressure element may be e.g. valve, membrane or any other element that, to enable passage of liquid through the element from its inlet side to its outlet side, requires that pressure at the inle't side be noticeably higher than pressure at the outlet side.

It appears to be especially advantageous if coffee is extracted at temperature of water from 60 °C to 75°C and pressure from 1 bar to 5 bar, saturating the coffee drink with e.g. C0₂ or N₂0. Preferably, the coffee product is led through pressure element by the effect of pressure difference at the inlet side of the pressure element and the outlet side of the pressure element of value within 5 bar and 15 bar. This value of difference of pressure at the inlet and outlet side of pressure element reliably ensures a suitable development of flavour characteristics of coffee drink.

Two preferred examples of preparation of coffee are as follows:

Light morning (or late afternoon) coffee

A dose of 7 grams for 125 ml. of water for extraction (2 cups - 15g for 250ml) . Under temperature near 65°C, extraction duration about 3 minutes and with pressurizing of mixture C0₂ and N₂0 to pressure near 5 bar, after second phase of pressurizing with increased pressure of 15 bar (passing through pressure element) smooth, highly aromatic and amply frothed coffee drink is produced. Small strong espresso (Picollo after main course)

A dose of 7 grams for 100ml of water is used for extraction. (2 cups 15g for 200ml) . Under temperature near 70°C, extraction duration about 4 minutes and with pressurizing N₂0 to pressure near 5 bar, after second phase of pressurizing with increased pressure of 12 bar (passing through pressure element) strong coffee drink with thick dark froth and intense taste is produced.

It is also necessary to mention health and ecological aspects related to the method proposed by the present invention. Researches have proven that most coffee is consumed in the north Europe - in Scandinavian countries, where the consumption makes in average up to 10 kg per person and year (in Czech republic it is about 2 kg) . Though, representative researches (about 10 000 respondents) have shown a lower percentage of cardiovascular disorders in these states than in other compared states. Finns owe lower percentage of cholesterol in blood to the fact that in their country a method of preparation of coffee has changed. Up to 75% of coffee consumers prefer preparation of instant coffee or coffee dripped through paper filter. Using these two methods, mainly heavier diterpens are trapped, these are substances such as cafestol and kahweol. The same affect is achieved using method of preparation of coffee drink according to the present invention, wherein the most dangerous part of coffee - coffee sediment, which includes the harmful substances, is not pressurized. Due to a lower temperature of extraction (65 - 70°C) changes of coffee oil, which is from the most part formed by triglycerides of linolenic and palmitic acids - so substances similar to iipids present for instance in vegetables, already do not occur. Due to the lower temperature necessary for preparation of coffee savings on energy needed to heating water are also achieved. Coffee maker is also more quickly prepared to produce the so called morning coffee. Also, thanks to the lower temperature of preparation it is possible to consume coffee earlier after it is served. Temperature of served coffee should be near to an optimal temperature for consumption - i.e. 56°C.

All components making coffee tasty - light oils, aromatic gases, froth saturated with oxide, are extracted to the surface of drink and thus they are included in coffee product obtained by the extraction in the course of the method according to the present invention, in accordance with patent claims (especially claim 1) . On the contrary, all unhealthy substances that originate during roasting such as carcinogens, all heavy oils, diterpens and substances increasing level of cholesterol in blood, deposit at the bottom in the coffee- grounds and thus, they are not included in coffee product obtained by extraction using the method according to the present invention.

The advantage of this new method of preparation of coffee according to the present invention may also be seen in the fact that in the second phase of preparation of coffee - i.e. during pressurizing and possible filtrating, coffee product obtained by the extraction is pressurized together with froth and aromatic gases, in contrast to classic method of preparation of espresso, however, coffee-grounds are not pressurized against filter. Therefore, as a result, the obtained coffee drink is smoother since it does not comprise small coffee particles that would be pushed through filter (coffee - grounds at the bottom of classic espresso) and moreover, which is considering the health and taste aspects essential, it includes substantially less harmful substances that are otherwise comprised in coffee drinks obtained by traditional methods as discussed above. This is because during the traditional methods of preparation of coffee by pressing through filter and as a consequence of being subject to high temperature (in the case of classic espresso up to 98 C) the coffee-grounds release undesirable flavour and unhealthy substances that manifest as bitter and stomach irritating adulterants that deteriorate resulting quality of drink. For this reason there are many people who cannot drink classic espresso and for the same reason many people mend the flavour of coffee by adding sugar, cream etc. to change the aftertaste .

Modifying the taste of coffee has become so spread that as a result of substances being added to coffee most consumers even do not know how old or stale coffee they are consuming is, whether oils comprised in coffee are not already rancid etc. For these reasons coffee gourmets do not drink espresso and flavour coffee at least.

Resulting taste quality of prepared coffee drink can be influenced in a broad spectrum depending on method of preparation and by changing variables. After setting the apparatus (coffee maker) , the variables may further remain unchanged and the coffee maker prepares anytime drink of the same flavour. As already mentioned above it is possible to use any usual sort of coffee, even the sort that would not be suitable for a classic espresso, for new method of preparation of coffee according to the present invention. Further, it is possible to use coffee which is ground to any coarseness and also to change extraction period according to need. Also, the range of temperatures suitable for extraction may be from 60 to 90 °C. The method can be used for preparation of a weaker drink, which is more suitable for a later consumption or very strong, fully aromatic drink with a rich froth. By changing pressure of water to be used for extraction and mainly by changing pressure to be used in the second phase for pressurizing it is. possible to achieve an optional level of frothing. Final flavour characteristics within broad range can also be achieved by choosing proportion of amount of ground coffee to amount of water in which drink is extracted. All these variables can be combined depending on desired resulting flavour and wish of consumer. The range varies from very thin drink kept in container and ready for a later consumption (known from American gas stations) up to extra strong drink with rich froth (Picollo known from coffeehouses in Venetia) .

Another advantage of the proposed new method of preparation of coffee can be seen in a possibility to influence the taste of resulting coffee drink by adding flavour and aromatic ingredients into coffee product obtained by extraction before it is led through pressure element or possibly alternatively only after it passes through pressure element. Besides soluble substances also gases and mixtures of gases with flavour substances can be used for the flavour and aromatic ingredients. This will enable to saturate the drink with new flavour ingredients that could not be used before.

From the ecological contribution point of view it is necessary to mention the following. Coffee is after oil the second biggest world commodity as far as the volume and value of business transactions realized per year are concerned. Daily many tons of coffee prevailingly prepared in coffee machines are consumed. In these coffee machines temperature near boiling point (temperature about 95°C) is used for preparation of classic espresso. The proposed method of preparation of coffee drink which enables to prepare espresso without causing thermal shock and changing flavour characteristics of extracted substances (coffee cannot be burnt) allows to use far lower temperature - temperature close to 70°C thanks to longer extraction period. It appears that in such a case there are 25% energy savings. These savings, on a world scale, could represent up to several terawatts of saved energy per day.

Finally, it will be understood by a person skilled in the art that the present invention is not limited to the described embodiments but can be modified in many different ways without departing from the scope of the invention as defined in the appended claims. For example, variant embodiments of pressure elements and the pressure and underpressure means which would fulfill required functions within the scope of the present invention will be apparent to a person skilled in the art based upon the present description.

Claims

1. A method of preparation of a coffee drink, wherein an overall amount of coffee to be extracted is provided, then the amount of coffee is extracted in water under certain pressure, characterized in that: after finishing extraction of the overall amount of coffee, the coffee product obtained by the extraction is led through a pressure element by the effect of increasing the pressure acting on the coffee product at the inlet side of the pressure element to value that is higher than value of pressure during the extraction and higher than value of pressure at the outlet side of the pressure element, and the coffee product is thus pushed through the pressure element.

2. The method according to claim 1, wherein along with increasing the pressure acting on the coffee product pressure at the outlet side of the pressure element is decreased.

3. A method of preparation of a coffee drink, wherein an overall amount of coffee to be extracted is provided, then the amount of coffee is extracted in water under certain pressure, characterized in that after finishing extraction of the overall amount of coffee the coffee product obtained by the extraction is led through a pressure element by the effect of decreasing pressure at the outlet side of the pressure element to value that is lower than value of pressure acting on the coffee product obtained by the extraction at the inlet side of the pressure element.

4. The method according to claim 3, wherein along with decreasing the pressure at the outlet side of the pressure element the pressure acting on the coffee product obtained by the extraction at the inlet side of the pressure element is increased.

5. The method according to any of preceding claims, wherein coffee is extracted under water temperature raging from 60 °C to 75°C and under pressure from 1 bar to 5 bar.

6. The method according to any of preceding claims, wherein the coffee product is led through the pressure element by the effect of difference of pressures at the inlet side of the pressure element and the outlet side of the pressure element being of value 5 bar to 15 bar.

7. The method according to any of preceding claims, wherein during extraction of coffee the coffee product obtained by the extraction is at the same time filtrated.

8. The method according to claim 7, wherein coffee product obtained by extraction is additionally filtrated also after finishing the extraction.

9. The method according to any of claims 1 to 6, wherein coffee product obtained by extraction is filtrated only after finishing extraction of the overall amount of coffee before leading the coffee product through the pressure element.

10. The method according to any of preceding claims, wherein an additional component is introduced into the coffee product obtained by extraction and is led along with the coffee product through the pressure element.

11. The method according to any of preceding claims, wherein after leading coffee product through the pressure element an additional component is introduced in the mixture.

12. The method according to claim 10 or 11, wherein the additional component includes aromatic or flavour essences.

13. The method according to any of claims 10 to 12, wherein the additional component includes C0₂ and/or N₂0.

14. The method according to any of preceding claims, wherein the pressure element is a pressure valve.

15. The method according to any of preceding claims, wherein coffee product obtained by extraction is led through the pressure element into a container.

16. The method according to claim 15, wherein coffee product obtained by extraction is led through the pressure element into vacuum thermo-container.

17. The method according to any of preceding claims, wherein a variable, combination of variables or all variables influencing resulting flavour of coffee drink are set to desired concrete values to obtain coffee drink of a desired specific flavour or quality.

18. The method according to claim 17, wherein the variables are variety, quality, coarseness of grinding of coffee, extraction period, temperature of extraction, pressure of water during extraction, pressure at the inlet side of the pressure element during leading the coffee product obtained by the extraction through the pressure element, pressure at the outlet side of the pressure element, proportion of ground coffee amount to amount of water in which extraction takes place.

19. The method according to claim 18, wherein for extraction a dose of 7 grams per one cup is used for 125 ml of water under temperature about 65°C, duration of extraction about 3 minutes, an additional component C0₂ and N₂0 under pressure about 5 bar is used, and the mixture is pressurized by increased pressure of 15 bar and led through the pressure element .

20. The method according to claim 18, wherein for extraction a dose of 7 grams per one cup is used for 100 ml of water under temperature about 70°C, extraction period of about 4 minutes, an additional component N₂0 under pressure about 5 bar is used, and the mixture is pressurized by increased pressure of 12 bar and led through the pressure element.

21. An apparatus for preparation of coffee drink, comprising a vessel (5, 13), in which an overall amount of coffee to be extracted is placed, a feed (2) for supplying water to coffee to be extracted, and filter means placed in the vessel (5, 13) for filtering coffee product obtained by extraction, characterized in that it comprises a pressure element positioned at the outlet from the vessel (5, 13) for leading the coffee drink out of the vessel (5, 13) under a discharge pressure that is higher than pressure under which extraction takes place and higher than pressure at the outlet side of the pressure element, and a pressurizing means to increase pressure inside the vessel (5, 13) to the value of the discharge pressure.

22. The apparatus according to claim 21, wherein it comprises an underpressure means to decrease pressure at the outlet side of the pressure element while the pressurizing means are increasing pressure inside the vessel (5, 13) .

23. An apparatus for preparation of coffee drink, comprising a vessel (5, 13) , in which an overall amount of coffee to be extracted is placed, a feed (2, 17) for supplying water to the coffee to be extracted, and filter means placed in the vessel (5, 13) for filtering coffee product obtained by the extraction, characterized in that it comprises a pressure element positioned at the outlet from the vessel (5, 13) for leading the coffee drink out of the vessel (5, 13) under a discharge pressure that is higher than pressure at the outlet side of the pressure element, and an underpressure means to decrease pressure at the outlet side of the pressure element.

24. The apparatus according to claim 23, wherein it comprises pressurizing means to increase pressure inside the vessel

(5, 13) to the value of the discharge pressure at the time when pressure at the outlet side of the pressure element is decreased by the underpressure means.

25. The apparatus according to any of claims 21, 22, 24, wherein the pressurizing mean^'s is a lower part (6) positioned in a lower portion of vessel (5) and slidable to increase pressure in the vessel (5) to the discharging pressure and adapted to accommodate the overall amount of coffee to be extracted.

26. The apparatus according to any of claims 21, 22, 24, wherein the pressurizing means is a pressure feed (16) for supplying a pressure medium into the vessel (13) .

27. The apparatus according to claim 26, wherein the pressure medium comprises an additional component comprising e.g. aromatic or flavour essences or carbon dioxide.

28. The apparatus according to any of claims 21 to 27, wherein the filter means is filter (4) provided with a draw bar for sliding movement of the filter (4) inside the vessel (5) to facilitate removal of coffee-grounds from the vessel (5) and the pressure element is a pressure valve (8) .

29. The apparatus according to any of claims 21 to 28, wherein it includes a container (19) at the outlet side of the pressure element to receive the coffee drink.

30. The apparatus according to claim 29, wherein the container

(19) is airtight connected to the outlet side of the pressure element and provided with underpressure means for decreasing pressure in the container (19) .

31. The apparatus according to claim 30, wherein the underpressure means to decrease pressure in the container (19) is a pressure hose (18) connected to a device for pumping air from the container (19) .

32. The apparatus according to any of claims 29 to 31, wherein the container (19) is a vacuum ther ocontainer for keeping temperature of coffee drink.

33. The apparatus according to any of claims 29 to 32, wherein the container (19) is provided with a discharge nozzle (21) at the bottom of the container (19) .

34. The apparatus according to any of claims 29 to 33, wherein the container (19) is provided with an insulating layer (20) and a heating device (22) .

35. The apparatus according to any of claims 21 to 34, wherein .the pressure element is a pressure valve (8, 15) .