GB2053668A - Improvements in or relating to the preparation of coffee infusions - Google Patents

Abstract

A process for preparing infusions of aromatic substances such as coffee and tea comprising the steps of confining a predetermined mass of discrete particles of the substance in a closed water permeable supporting and filtering container 1 of predetermined dimensions, and repeatedly submerging the container with the substance therein within a predetermined volume of hot water, the relationship of the container dimensions and the mass being such that when the container is submerged in hot water the thickness of the mass therein is maintained less than a predetermined critical thickness corresponding to irreversible self-compactness. The invention also provides several differing constructional forms of containers for carrying out the process. <IMAGE>

Description

SPECIFICATION Improvements in or relating to the preparation of coffee infusions This invention relates to the preparation of infusions of coffee, tea and other similar infusionable substances, by using disposable sachets.

Infusionable aromatic solid substances such as coffee and tea show marked handling difficulties when confined in small containers such as disposable filtering sachets. It happens in the particular case of coffee that under the usual circumstances, when after being ground in the customary way it is confined in a sachet othe like and then dipped in hot water, its grains of very small size give out a first and small portion of their water soluble aromatic essential oils.These essential oils when mixed with the air trapper between the grains and the remaining sections of the sachet that are unoccupied by the material form a large amount of strong and elastic bubbles occupying all the available free spaces, that is, those spaces between the grains of particles themselves and the space not filled by the mass of grains, thus forming a sort of strong mat-plug between the material to be infused that is confined in the sachet, and the surrounding water. Thus, the outside water cannot effectively enter the sachet to reach the coffee to be infused and the aromatic oils of the latter will not be freed in a greater degree than the initial very small amount.In other words, the ground coffee is "drowned" when subjected to the action of hotwaterwhile it is confined in a container having little free space such as a conventional sachet like the well known tea sachets.

Coffee has other behaviour characteristics when submitted to the action of hot water. It seems that these characteristics have not been known in full until now, at least in its association with the problem under consideration. It is from an elaborated obsedvation of these facts that results what is deemed to be the groundwork or starting point of this invention that encompasses, however, other factors.

These characteristics refer to the property of ground coffee tending to compact itself on contact with water by absorbing a comparitively large amount of this liquid. This compacting phenomenon has in turn the peculiarity of showing two states.

One that can be called Low Compactness, from which it still can be converted in a liquid medium, to the uncompacted state in which the grains are not pressed together and may be left free. The other degree of compactness that can be termed High Compactness results from a new behaviourthat, as a homongeneous mass, follow the united grains of coffee. These remain bound together, resisting and finally preventing its separation (decompacting) by water. This degree of compactness is called, for a better understanding ofthe invention, "irreversible compactness", as in this state it is not possible to bring about a conversion to the state of mutual freedom of the grains without which an appropriate treatment of the grains to extract the essential oils is not possible.

The "irreversible compactation" of coffee is in fact produced by the combined action of both the higher specific weight gained by the originally dry grains when soaked in water with the consequence that those located above press the grains below and are pressed in turn by those above then and the sealing action of the essential oils that as soon as they are given off are solvated in water and then confined in the interstices between the grains and even in the pores of the grains themselves.

The particular phenomena that in this respect have been observed are that the coffee grains when they are confined and immobilised at the bottom or adjacent areas of a container and submerged in water, behave as a homogeneous mass. Additionally, and this is fundamental fact, the whole coffee mass in accordance with its physio-chemical composition (insoluble parts and soluble components) and the degree of grinding i.e. the grains size, have a definite and critical thickness beyond and above which it behaves as irreversibily compacted, so that its grains cannot be easily dispersed in water.This discovery, not only by itself but joined to the consequent occurence of the creation of suitable conditions to enable a mass of ground coffee in repeated states of dispersion in waterto be subject to successive washings to effect progressive extractions of soluble oils have given as a result the process of this invention and the means adapted to carry the invention into practice.

Tea leaves (not ground) have a similar behaviour to coffee, although this behaviour is nearly entirely due to the higher specific weight of the leaves when they are water saturated, as the soluble aromatic components have very low values of density and viscosity. In this sense, generally speaking, all the above considerations referring to coffee are valid for tea, particularly those related to the irreversible compactness level. Other aromatic infusionable substance of a kind similarto coffee and tea, e.g.

mate, the various known medicinal herbs, can be treated by the present process.

Also ground coffee is sensitive to atmospheric oxygen which oxidises the aromatic oils and thus requires protection from such oxidisation.

A main object of this invention is to make possible the preparation of infusions of aromatic substances such as coffee and tea, through the use of filtering sachets or equivalent.

Another object ofthis invention is to provide a process adapted to prepare the above mentioned infusions under optimum conditions.

A further object is the possibility of optimally handling, with the help of sachets, aromatic substances like common tea, mate and others, without resource to a previous grinding to reduce them to a powder, as it is usually done. In the particular case of common tea, the possibility of handling the material in leaf form, with all the advantages of the disposable sachets, is of the utmost importance.

It is also an object to achieve practical conditions, both of an industrial and consumer order, that can maintain the aromatic substances with which the infusions are to be prapered, especially coffee, isolated from the atmosphere under easy conditions free of special requirements for their use.

According to the present invention there is pro vided a process for preparing infusions of aromatic substances such as coffee and tea characterised by confining the appropriate infusionable substance in a supporting and filtering enclosure in the required amount to make a given infusion and such that it has a thickness which is less than a critical lowest thick ness corresponding to irreversible self compactness, sinking said infusionable substance, together with a filtering and supporting container, in a quantity of hot water suitable to provide an infusion having the desired concentration, and effecting repeated washings for extracting the aromatic com ponents of the infusionable substance, by promoting successive states of decompactation of reversible compactness of the particles forming the mass of the infusionable substance, by means of repeated admissions and discharges of water, until the desired degree of concentration of the infusion is reached.

The scope of this invention also embraces such means as the positive acting filter sachets having such design that they provide for the treatment of coffee according to the above mentioned process, and the means to preserve said aromatic infusionable substance.

The invention will be described now by way of example only with particular reference to the accompanying drawings. In the drawings: Figure 1 is a perspective view of a filter or sachet in accordance with the present invention; Figure 2 is a section taken through I-I of Figure 1; Figure 3 is a schematic view of the composition of planes of the end tabs of the sachet shown in Figure 1, said planes or parts being shown slightly separated before taking the position in which they are sealed together; Figure 4 is a perspective view of a variation of the sachet of Figures 1,2 and 3; Figure 5 is a perspective view of a variation of the embodiment of Figure 1 to 4; Figure 6 is a perspective view of a sachet similar to the one illustrated in Figure 5 but unfolded and loaded with coffee;; Figure 7 shows the sachet of Figures 5 and 6 loaded with coffee, manually closed and half introduced in a cup of water; Figure 8 shows the shape and position of the sachet of Figure 7 when it has been totally introduced into the water contained in the cup; Figure 9 is a general perspective of a filtering unit in accordance with the invention; Figure 10 is a side sectional elevation of the filtering unit of Figure 9; Figure 11 is a cross section on the plane A-A of Figure 9; Figure 12 is a cross section of the filtering unit of Figure 9 showing it in an operative position; Figure 13 is a cross section of a unit similar to that of Figure 11, but showing the container capsule of infusionable substances partially extended;; Figure 14 is a side sectional elevation of a filtering unit which differs from the examples in Figures 9 to 13 in that that container capsule of infusionable substances is joined to the lower part of the unit on the inside of the top end of the latter, and Figure 15 is a perspective of the top part of another form of filtering unit.

The same symbols have been used in the different Figures for similar parts A process for preparing infusions of coffee, tea or similar material comprises the following steps: 1. Arranging a definite and suitable amount of ground roasted or toasted coffee - in the amount required to provide the desired infusion-in a container, e.g. a filter container, adapted on the one hand to suitably filter the coffee and enabling on the other hand a quick admission and discharge of water.Being given that coffee or any mass theoretically uniform of ground coffee, has its own critical thickness or irreversible self-compactness, beyond which, under practical conditions, the dispersion of the grains to be exposed to the action of water for extracting soluble substances is impossible, the coffee container, in addition to being capableofassum- ing an upright position, should have such a shape and dimension as to enable on the one hand the confinement in the bottom of the container of the amount of coffee required for the volume of infusion to make, while on the other hand it must be conditioned to so arrange itself that when submerged in water its thickness will be less than the minimum thickness for irreversible self-compactness.

2. Sinking the mass of coffee jointly with its supporting and filtering container in a mass of hot water, the quantity of which is sufficient to allow the provision of an infusion of the desired concentration.

3. And promoting repeated decompactness states in the mass of coffee, i.e. in the grains of the mass, which in this case keep mutually separated and more in contact with the water, by means of the filtering container, forcing the hot water of the infusion to fill and to be discharged from the inside of the container, in such a way as to produce an intense and repated washing for extracting soluble substances while not allowing the latter to significantly pass to the gaseous state.The admission, discharge and generally the recirculation of water in the enclosure (filter container) may be secured in various different ways, among which the following are preferred: a) Wholly or nearly wholly sinking and removing from the infusion water the coffee contained in the enclosure or filter container; b) Promoting alternative volume changes in said filtering enclosure, e.g. reducing its size to expel water and then letting it restore its original dimensions to promote the refilling with water.

Now referring to Figures 1 to 3 apparatus for carrying out the process comprises a closed filtering bag orsachetwhich is loaded with an appropriate amount of ground coffee. In the sachet, a is a body having a generally upright elongate shape. It should be explained that the whole body of the sachet is conditioned with a sense of verticality, so that when without effort it is freely placed on to a horizontal surface, which may be the bottom of a container (a demitasse, a cup, a jar, etc.) it tends to arrange itself in an upright position i.e. with its bottom end lying on the surface.

The sachet is made starting from a tube b of square section (Figure 3) made of conventional filter paper, very thin and provided with a thermoplastic adhesive coacting on one face, for heat sealing. The paper is of the same kind as the one currently used for the well known tea sachets. It is well known that this paper is highly permeable to water and at the same time it filters out the solids. The tube is shaped by appropriately folding a filter paper band 1 and sealing its superimposed lateral edges 2 and 3.

The shape of the sachet in its inoperative condition when adapted it be packed with others of the same kind, is generally that of an elongated double wedge and is a result ofjoining the respective extreme sections of two opposed walls 4 and 5 of tube b, which are drawn nearer by inward folding of the other two walls 6 and 7 of the same tube (Figures 2 and 3). By shaping the above mentioned ends tabs 8 and 9 are formed having the double function of providing a better end closure and making easierthe handling of the sachet in its use.

It should be m&commat;de madeclearthat, strictly speaking and as shown in Figure 3, the side walls 6 and 7 keep interposed between walls 4 and 5 when they are joined, pressed together and sealed to form the above mentioned tabs Band 9 to close the sachet end.

As shown by the example of Figure 1 the sachet is loaded with a quantity of ground coffee C that for the inoperative condition of the sachet having its body a generally flattened, fills about one half of the inside space. This quantity of. coffee has to be such according to the nature and characteristics of the coffee involved that when the sachet is displaced and in its greatest amplitude, in the operative condition, with its enlarged base nearly flat &commat;nd and horizontal, it will occupy such a volume that a thickness or height is reached that is lower than the critical lowest limit of irreversible compactness of the coffee to provide an infusion of the appropriate intensity.

In all cases, both in the inoperative and in the operative condition of the sachet, there remains over the coffee occupying its bottom section a large free section 10 (Figure 1) which together with the bottom space enlarged under operative conditions forms a coffee decompacting chamber when it is submitted to the action of water contained in a vessel under similar conditions to those shown in Figure 8.

The sachet that is shown in Figure 4 differs from the embodiment illustrated in the preceding Figures only in that its body d is shaped from a tube of circular section. The lateral depressions of the preceding example are not formed in this case, so that the shape of the body is generally circular or slightly oval, both for the inoperative and the operative conditions. Also this sachet is provided with only one tab 11 for handling. The bottom end is sealed along the edge 12.

Although the examples discussed in reference with Figures 1,2 and 3 cover the majority of the possible embodiments of the present sachets it must be understood that there is a range of foreseeable variations. For example end tabs can be dispensed with and other cross sectional shapes can be used e.g. rectangles, ovals, etc.

The mode of operation with the sachets of Figures 1 to 4 is practically the same for all the embodiments illustrated. The sachet is gripped at its upper end by the tab arranged to this effect in the sachets provided with those tabs in the case of the appropriate examples and while keeping them in the vertical position that they naturally take, they are slowly dipped, starting from its bottom end, into a vessel (a demitasse, a cup, a jar, etc) in which water required for the infusion has been placed. Obviously, for a given quantity of coffee contained in a sachet, the quantity of water appropriate to make an infusion of the desired intensity should be used. This first step may be inverted by first placing the sachet into the vessel and then pouring the water over.Once the sachet has been submerged into the water, it is partially or totally raised and lowered until it is out or substantially out of the vessel, to so promote successive decompactations of the coffee mass while the water is drained off with the consequent washing of the coffee aromatic soluble substances and to promote a further admission of water when it is lowered again. This operation, repeatecl several times promotes a renewed extraction of the soluble aromatic components of the coffee. When through these repeated operations the desired concentration of the infusion has been reached, the sachet is taken out and the infusion ready for drinking.These sachets may also be operated by leaving them practically all the time in the vessel and promoting the exit of the water enriched with solvated coffee and the admission of new water through the action of a spoon used to press the submerged wall of the sachet and then removed to enable a further admission of water. A mixes3 mode consists in raising and lowering the sachets and now and than pressing with a spoon. What is important is to promote a repeated admission and discharge of water from the sachet.

It should be also pointed out that when the water initially enters the sachet, it sim ulianeously wets the sachet's walls, at least in its bottom half, as well as the inside coffee. The increased weight of the coffee (it is now a water-impregnated coffee) and the soften ing of the paper of the sachet body, force the whole mass of coffee to descend and exert pressure on the extreme bottom or base section of the sachet, which is notably widened and the same thing happens with the nearest part of the sachet body that is also widened up to its maximum section.Thus the base is considerably widened, markedly in the sachets of square or rectangular section as in the embodiments of Figures 1 to 4 and the bottom assumes a generally prismatic, cylindrical shape or the like.

Referring to Figures 5 and 7 there is shown a positive action sachet similar to that of Figures 1 to 4 but opened at the top and empty. This is so because in a further embodiment of the invention it is possible to provide empty sachetsto be filled subsequently with coffee. The sachete has a body 13 shaped like a nearly flat wedge (Figure 5) ending at the bottom in a narrow sealing belt 14. It appears externally as a relatively thick rectangular plate, as the side walls 15 and 16 and the interleaved remaining walls 17 and 18, which are folded at the centre, form a thick laminar body. When using this sachet it is slightly opened, as shown in Figure 6, for filling with the required amount of coffee f.The sachet is then grip ped with the fingers from its top by pressing together the faces 15-16 (Figure 7) for shaping the sachet like the sachetofthe embodiments of Figures 1 to 4, with its top end closed and provided with a gripping tab. The bottom end of the sachet is then introduced into a demitasse containing water i and operated according to the method described with reference to Figures 1 to 4.

Figure 8 shows the sachet when submerged with the water of the demitasse inside to decompact, i.e.

to slightly separate, the small grains of ground coffee contained inside. The bottom section of the sachet is markedly enlarged as a result of the decompacting of the coffee and assumes a nearly prismatic shape as shown in Figure 8. When the sachet and its contents are raised above the liquid level, the inside water, which has solvated part of the essential oils of the said coffee, is drained by gravity from the sachet and falls into the liquid remaining in the demitasse.

When repeating one or more times the introduction and withdrawal of the sachet new extractions occur, by washing of the essential oils and the latter enrich the water in the demitasse, thus providing an infusion of increasing concentration.

The following is an example of the functioning of the process. A sachet as shown in Figures 1 to 3 is used and has the following measurements: length, excluding the flaps at the end: 110 mm. Square tubular section of the sachet (as if lacking the lengthwise folds): 32 mm per side. Content of toasted coffee, of standard granulometre, such as of ground coffee for paperfiltercoffee pots: 12 grammes. Operative thickness of self compacted coffee saturated in water, immobilised in the horizontal bottom of the sachet: 18 mm; critical lowest limit of irreversible compactness of such coffee: 22 mm. Volume of water used: 120 cc. Watertemperature:90"C. Operation time of sachet, under constant and repeated immersions and withdrawals: 80 seconds.To prepare a larger quantity of the infusion, for example 500 cc, a similar sachet should be use, but of a 44 mm per side section and an effective length of 160 mm.

Toasted coffee of the same standard type of grinding: 30 grammes.

Infusioning time: 180 seconds maintaining the sachet in continual movement dipping it in and withdrawing it from the infusioning water. If milk is being used as infusioning liquid the same sachets can be employed, but it is advisable to use the same quantity of toasted coffee with 10% glaced sugar. Infusioning time from 30 to 40% more than when using water.

If sachets of different sections are used such as circular sections in general the same section area should be maintained as if it were square. The behaviour of the sachet is normally always the same, whatever its form. When, as is normal, sealed sachets are manufactured fortheir massive sale, obviously the type of coffee and the filter paperto be used should be standardised, and this applies also to the amount of coffee to be used in relation to the size of the sachet, and to the quantity of the infusion for which the sachet will be used. The size and shape of the sachet and the quantity and type of coffee must also be conditioned not to surpass the max imum critical thickness of reversible decompaction of the coffee.

When using tea leaves to obtain an infusion of a 160 cc. a sachet of the shape and size of that illus trated in the examples of Figures 1 to 3 can be used, this being 105 morn. in effective length and section sides of 22 mm., 4 grammes of tea and some 30 seconds of operative time with cyclic movements, as in the case of coffee. Milk can also be infused using the same quantities and only changing the operative time which should be 60 seconds.

With reference to the examples of Figures 9 to 13 it will be appreciated thatthe unit comprises (Figures 9 and 10) two main parts: one lower filtering part j and one higher partkwhich is a container capsule of the infusionable substances. These two main parts are joined in such a way that theyform a complete and coherent functional unit of a generally upright shape.

As shown in Figures 9 to 13 the lower filtering part comprises a tubular square section 19 of thermosealable filter paper. This tubular part has two lateral folds 20, 20' which in the manner of a bellows allow thesesquaresection (Figures 9,10,11 and 13) to be flattened with throttling of its top end, which is the case when the unit is inoperative with the capsulek full and closed and the lower filtering partjfolded.

Capsule k which contains the infusionable substances also consists of a tubular square section 23 made ofthermo-sealable waterproof paper, which has, like the lower filtering partj two lateral convergent folds 24,24'.

The sections of the two tubular elementsj and k are almostthe same and only have a slight difference to allow for the telescopic coupling of the intermediate zone 23 ofthe (Figures 9 and 10), the lower end of capsule k remaining outside the upper end of filterj. The two elementsj and k are united by virtue of the thermo-plasticity of their component materials in the coupling area 23, by means of, for example, a series of pressure and heat produced soldering grooves 24. The same conventional pressure and heat procedure is used, once it has been filled with powdered coffee or other infusionable substances, to close the upper end of capsule k with a closing flap 25 on which the soldering grooves are applied.

As already indicated, the purpose of capsule k is to contain the coffee or other infusionable substance / which is not illustrated in this example (it can be seen in the lower filtering partj of Figure 12) and which entirely fills the interior of k, taking up all the possible room of itto eliminate the presence of air which is a noxious element.

Thus, and as has been explained, the infusionable substance, as long as the unitforthe preparation of infusions is in a non-operative position (Figure 9) is contained and protected within capsulekwhich has the dual role of holding the substance (as if itwere a container) and preserving it from contact with air, the latter because of the waterproof nature of paper used for the capsule. The lower filtering part mean while remains folded and also in an inoperative posi tion. When the unit is to be used to prepare an infu sion with its contents, the procedure is to open the closed soldered area formed by the soldering grooves 24, in such a manner as to separate the soldered parts.This means that the sides which are in contact with each other (Figures 9, 10 and 11) and the corresponding sealed closure in the area of the telescopic coupling of the partsj and k can be moved to a (operational) position in which, as shown in Figures 4 and 5, they become separated and produce a communications area between the inside of capsule k and the inside of the filtering bodyj, so that the coffee or other infusionable substance / initially contained in the capsule k can freely fall into the inside ofj as shown in Figure 12. To produce this opening it is necessary to pull the soldered parts apart from outside, and this is achieved by using any of the opposite pairs of folds 22-22' of the capsule in the coupling area 23 ofj andk, as shown in Figure 13.It should be noted that Figure 13 is an intermediate position between that of fully folded (as per Figures 9,10 and 11) and of fully open (Figure 12) and this occurs when starting to pull the folds 24-24' from a position as shown in Figure 11. The infusionable substance / begins to fall into the interior a as soon as the opening of the throttled sector is begun as indicated.

It should be noted furthermore, that although in principle it is technically possible to achieve an effi cientjoining of the walls of the two coupled parts, with the possibility of separating the inter-solded walls, to obtain this implies a series of considerable difficulties, as it is necesaryto guarantee the nonrupture of the coupled walls when opening out the coupling. An efficient solution for the practical problem has been achieved by inserting tearable sheets sandwiched between the inside walls of the waterproof paper ofcapsulekwhich allow for and even aid the process of throttling closure, but because of their slight mechanical resistance facilitate at the cost of being torn, the separation of the other walls without the risk of the latter being broken.In fact, this is achieved in our case by introducing the laminated material (conventional flettype filter paper) in the base of capsule k in the throttling area 23. This can be observed in detail especially in Figures 10, 12 and 13.

The example of Figure 14 shows a variation which is possible under strict manufacturing conditions. In this case, the coupling of the waterproof container capsulem which contains the infusionable substance n made of waterproof paper 27 is coupled to the lower filtering parto made of filter paper 28 in an inverse manner, that is with the filter paper 28 on the outside and the waterproof paper 27 on the inside.

The incommunicability in an inoperative state between m and o is achieved by soldering the intermediate zone 29 by means of soldering grooves 30.

The version of Figure 15 includes a pairof pulling flaps 31 made of thermo-sealable paper which are soldered to the sides of the coupling zone 32 of the two parts, for pulling open the throttled zone of the unit from outside. This solution is especially adequate in cases in which, unlike those shown in previous examples, the lateral folds of the parts are not very deep, in which case pulling one of the pairs, as demonstrated, is not efficacious. It should be noted that in the example of Figure 15 there is, as in previous cases, a capsulep containing infusionable substances and a lower filtering partq for the eventual filtering of the substances. In the example of Figure 15, the material of the capsule is inserted in the upper opening ofthe filtering partq.

It should be understood that the described structures can vary; thus, the partsj and k or their equivalents in other examples could have, without excluding others, rectangular, circular or oval sections, the paper used to make these parts may not be thermo-adhesive and the joining can be done with appropriate adhesive materials, the coupling of the two main parts can be done by inserting an intermediate, for example a tubular body, the throttling process to temporarily incommunicate the container capsule from the filter part can be replaced with, for example, a removable closing device at the bottom of the capsule.

When carrying this invention into practice, changes may be introduced in the conditions and steps of the method as disclosed, as well as in the constructive means used to operate said method, all this being comprised in the scope of the following

Claims (26)

claims. CLAIMS

1. A process for preparing infusions of aromatic substances such as coffee and tea characterised by confining the appropriate infusionable substance in a supporting and filtering enclosure in the required amount to make a given infusion and such that it has a thickness which is less than a critical lowestthick- ness corresponding to irreversible self compactness, sinking said infusionable substance, together with a filtering and supporting container, in a quantity of hot water suitable to provide an infusion having the desired concentration and effecting repeated washings for extracting the aromatic components of the infusionable substance, by promoting successive states of decompactation of reversible compactness ofthe particles forming the mass of the infusionable substance, by means of repeated admissions and discharges of water, until the desired degree of concentration of the infusion is reached.

2. A process as claimed in claim 1, wherein for reaching the repeated states of decompactation of the mass of coffee or the like in the filtering enclosure and the consequent extraction of the soluble aromatic substances, they are repeately submerged and withdrawn from the water, allowing the time required for draining the water from the filtering enclosure each time that said enclosure is withdrawn from the water.

3. A process as claimed in claim 1, wherein the decompaction state of the mass of coffee or the like confined in the filtering enclosure is created and the consequent extraction of the soluble aromatic substances of the coffee or the like is promoted by keeping submerged the filtering enclosure and the coffee or the like in the water and by promoting repeated admissions and discharges of water from the filtering enclosure.

4. A process as claimed in claim 3, wherein the repeated discharges and re-admissions of water into the filtering enclosure are promoted by alternatively making smaller and enlarging and filtering enclosure.

5. A sachet for preparing infusions of aromatic substances like coffee and tea by a process as claimed in claims 1 and 4, characterised in that it comprises a closed and folded bag made of filter paper or the like having a high permeability to water, said bag containing a mass of roasted and/ortoasted coffee orothersimilar infusionable substance, said bag being elongate and in an initial inoperative posi tion capable of assuming an upright position and including a lower end adapted to allow by enlarge ment under operative conditions for the total condi tioning of the mass of coffee or the like contained therein, said mass of coffee or the like comprising a quantity of coffee orthe like that, for an enlarged operative position of the sachet, has a virtual thickness at the bottom thereof that is smaller than the critcial minimum thickness corresponding to irreversible self-compactness in a liquid medium, said bag being also adapted to arrange in its operative enlarged position for a complementary inner free space sufficient to allowforthe decompactation of the mass of coffee or the like in a liquid medium.

6. A sachet for preparing infusions of aromatic substances like coffee and tea by a process as claimed in claims 1 to 4, characterised in that it comprises a bag of high permeability filter paper of a generally elongate shape, which is folded and open at its top mouth, said bag including a lower end adapted to allow by enlargement under operative conditions forth total conditioning of a mass of coffee or the like comprising a quantity of coffee or the like that, for an enlarged operative position of the sachet, has a virtual thickness at the bottom thereof that is smaller than the critical minimum thickness corresponding to irreversible self-compactness in a liquid medium, said bag being also adapted to arrange in its operative enlarged position for a complementary inner free space sufficient to allow for the decompactation of the mass of coffee or the like in a liquid medium.

7. A sachet as claimed in claim 5 or claim 6, wherein two of the walls of the sachet elongate body are mutually opposed and between them are interposed another two also mutually opposed walls, all said walls being joined at their ends, so that the sachet body is shaped as a double wedge.

8. A sachet as claimed in any of claims 5 to 7, wherein the body is shaped starting from a square section tube, so that two opposed faces are joined together following a right line atthe lower end.

9. A sachet as claimed in any of claims 5 to 7, wherein the body is shaped starting from a rectangular section tube, so that two opposed faces are joined together following a right line at the lower end.

10. A sachet as claimed in any of claims 5 to 7, wherein the body is shaped starting from a tube having a closed curve section.

11. A sachet as claimed in claim 5, wherein the body has a generally symmetrical shape in the longitudinal direction and has two substantially equal ends.

12. A sachet as claimed in any of claims 5 to 11, wherein the lower end of the sachet body has an external flat extension shaped as a supplementary tab formed by a flattening of a section of the sachet body.

13. A sachet as claimed in any of claims 5 to 11, wherein the two ends of the sachet body are substantially alike and they end in a supplementary tab, each tab being formed by flattening a section of the respective end.

14. A sachet as claimed in claims 5 to 9 and 11 to 13, wherein the sachet body possesses two mutually converging plane and opposite faces, said faces forming at the base a dihedral angle.

15. A unit for the preparation of mainly aromatic infusions such as coffee and tea as claimed in any one of claims 5 to 14, wherein it includes in an elongate body one lower filtering part capable of receiving infusionable substances and a container and preserving capsule for the infusionable substances joined to the lower filtering part and isolated therefrom, and means actionable from the outside of the capsule to open the capsule for discharge of its contents into the lower filtering part.

16. A unit as claimed in claim 15, wherein the container and preserving capsule holding the aromatic substances comprise a tubular body telescopically coupled at its lower end to the upper end of the filtering part, both parts forming in their coupling zone by the adhesion of their inner walls, a removable throttling, which temporarily prevents communication between the container capsule and filtering part, and means actionable from outside the unit capable of causing through pulling on the throttling zone the release of the throttle by separating the walls.

17. A unit as claimed in claim 16, wherein in the coupling of the container capsule and the lower fills tering part, the walls of the capsule remain outside the walls of the filtering part.

18. A unit as claimed in claim 16, wherein in the coupling of the container capsule and the lower fills tering part, the walls of the capsule remain inside the walls of the filtering part.

19. A unit as claimed in any one of claims 15 to 18, wherein both the container capsule and the lower filtering part have a square section tubular construction and each have two lateral, longitudinal and convergent folds facing one another on opposite walls.

20. A unit as claimed in any of claims 15 to 18, wherein both the container capsule and the lower filtering part have a rectangular section tubular construction and each have two lateral, longitudinal and convergent folds facirtg one another on opposite walls.

21. A unit as claimed in any of claims 15 to 18, wherein both the container capsule and the lower filtering part have a circular section tubular construction and each have two lateral, longitudinal and convergent folds facing one another on opposite walls.

22. A unit as claimed in any of claims 16to 21, wherein the external actionable means to open out the throttled zone comprises said longitudinal lateral flaps formed in the two coupled zones as a result of the lateral folds.

23. A unit as claimed in any of claims 16 to 21, wherein the external actionable means to open out the throttled zone comprises a pair of pull out flaps incorporated and joined externally to the throttling zone.

24. A process for preparing aromatic infusions substantially as hereinbefore described.

25. A sachet for preparing aromatic infusions substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

26. A unit as claimed in claim 15 and substantially as hereinbefore described with reference to and as shown in Figures 9 to 15 of the accompanying drawings.