The present invention relates to methods and devices for preparing beverages using capsules containing a food substance, such as a substance to be extracted and/or to be dissolved. The invention relates more precisely to a method and a device for preparing, in an optimized manner, a variety of beverages from substances of different types.
The use of capsules containing a substance for preparing a beverage by extraction or by mixing under pressure is well known, particularly in the field of espresso-type coffees or soluble coffees, and is advantageous particularly for reasons of hygiene, storage freshness of the coffee and ease of use.
There are various machines for preparing beverages using “capsules” containing a substance to be extracted, such as ground coffee, tea or a substance to be dissolved or dispersed, such as soluble coffee, chocolate, milk or a mixture or simple combination of these substances.
The capsules may be closed capsules serving as a chamber for the injection of water and opening in order to release the liquid beyond a certain pressure threshold by means of the rupturing of a face of the capsule in contact with elements that are in relief. Water is usually injected by means of perforation through the capsule using a needle or spikes. An example of an extraction system of this type is described in Patent EP 0 512 470 B1 or, alternatively, EP 0 870 457. In the as yet unpublished European Patent Application No. 02000943.7, a description is given of a capsule having its own release-type means for rupturing a capsule film or membrane and thereby releasing the liquid extract when a pressure threshold has been achieved inside the capsule.
The capsules may also be permeable chambers of the filter type or, alternatively, semi-permeable chambers comprising a filter component.
It is known to use substances to be mixed (soluble or dispersible substances) and substances to be extracted under pressure using the same machine so as to offer a wider variety of beverages. For example, on one and the same machine, it is possible to prepare an “espresso” coffee when the capsule contains a ground coffee or a hot chocolate when the substance is a mixture of cocoa and powdered milk. However, it is observed that it does not suffice to fill a capsule with a different type of substance if a quality beverage—in terms of aroma, taste and/or volume of foam, for example—is to be obtained.
In particular, the injection, mixing or wetting conditions may have a considerable influence on the quality of the beverage produced. Depending on whether a substance, resulting from grinding, pressed down into a capsule is involved, or, alternatively, a substance to be dissolved or dispersed in a liquid, such as a soluble coffee or a milk-based substance such as a cappuccino, chocolate or the like is involved, the way in which the water circulates through the capsule has an influence on the extraction or mixing conditions and thus on the final quality of the beverage. Thus, a product such as coffee or chocolate has to be dissolved or dispersed rapidly and completely, producing, preferably, a foam; on the other hand, a soluble tea preferably has to be dissolved without producing foam. Dissolution or dispersion has to be total, homogeneous and rapid, without giving rise to lumps or froth. In the case of products to be extracted, such as ground coffee, the optimum wetting conditions are different. The product must be thoroughly wetted, thereby optimizing the water/coffee contact surface, without creating preferred routes for the water through the bed of coffee. The creation of a privileged route through the bed of coffee may result in too sudden an increase in pressure and thus too rapid a release of the extract despite the fact that the extraction time is insufficient and part of the coffee has not yet been correctly wetted.
The injection conditions may be improved, although this would only be in response to a particular problem or in connection with a particular substance. For example, Patent Application EP 1 299 022 A1 relates to a capsule cage comprising blades and a separate water entry for distributing the water through the capsule and eliminating the problems of obstruction and furring-up of the water-injection needles. For example, application EP 1 203 554 A1 relates to the shape of the piercing spikes for promoting water-flow conditions inside the capsule and preventing the rise of solid residues outside the capsule.
However, there are no known devices that aim to meet the different, often contradictory, resultant wetting requirements in the case of extraction or the mixing, with water, of a substance contained in a capsule. Consequently, known devices are ill-suited to the preparation, in a manner that is adapted on each occasion, of a wide range of beverages from substances of different types.