FR2538381A1 - Process for the recovery of inositol and optionally of sorbitol from aqueous extracts of almond husks - Google Patents

Abstract

An aqueous extract (containing soluble carbohydrates (sugar alcohols: inositol, sorbitol; sugars: fructose, glucose)) is passed through a zeolite molecular sieve capable of separating inositol or sorbitol from the other carbohydrates.

Description

 The present invention relates to the extraction of sugar alcohols, inositol and sorbitol, and of reducing sugars, fructose and glucose, from almond casings.

 Inositol is a widely used industrial compound, the relatively high cost price of which increases the price of products that require it. It is obvious that a large reduction in the cost price of raw materials and production costs can open up untold new outlets and lead to a very significant reduction in the cost price of this important constituent for many other products which contain it.

 Currently, the conventional methods of producing inositol must start from a precursor which is not inositol but can be transformed into inositol. Typical starting materials are rice husks, oat husks and corn infusion liquor.

Phytic acid is produced from these materials, and phytic acid must then be dephosphorylated to produce inositol. These processes are expensive and have a strong influence on the cost price of the final product.

 The Applicant has learned that inositol exists by itself in significant concentrations in the fractions of carbohydrates (carbohydrates) which can freely diffuse and which are contained in the almond casings. Thus, inositol is available in the form of a product which does not require chemical derivation operations, provided that it can be separated from the other extractable constituents of the almond casings, which includes other saccharides, polysaccharides and polyols, especially. It is an object of the present invention to do so, using inexpensive or inexpensive processes which do not require the "manufacture of inositol from some other compound. If the starting materials and operations are inexpensive , the cost price of inositol can be significantly reduced.

In fact, one can expect that the cost price of inositol, taking into account all the usual elements of formation of this price and the possibilities of selling by-products, now represents half the price of returns from linositol obtained by conventional methods from other starting materials.

 Inositol is a sugar-alcohol (cyclohexane hexol) that exists in almond casings with other water-soluble compounds, mainly sugars: sucrose, fructose and glucose, and with another sugar alcohol (hexol), sorbitol. The inventors believe that the present invention provides the first separation, at least the first that they know, in which inositol has been separated, industrially applicable, from sugars and another sugar alcohol. It will be observed that these other compounds, in particular sorbitol, have an important economic value in themselves.

The combination of fructose and glucose can be sold as a sweetener and, in some cases, may have a higher fructose / glucose level than sweeteners from many other sources. Sorbitol has its own uses. In addition, fructose can be economically transformed into mannitol, which is also an interesting sugar alcohol (hexol).

 It can be noted that at present, when they are used to obtain phytic acid to be transformed into inositol, the rice husks give only 1 inositol without providing useful by-products, provided that the inventors know, with the possible exception of calcium phytate.

It should be noted that the above advantages are all obtained by using what is usually considered to be a relatively low value material.

Sugars are most commonly extracted from cultivated plants, and extraction techniques have been developed to this end. However, conventional extraction techniques offer few guide elements for extraction from almond casings. For example, sugar is extracted from sugar beets in a diffusion process in which the sugar diffuses into water. Sugar is extracted from sugarcane by a strong crushing action which seriously damages the cellular structure. In sharp contrast, the present invention, in its preferred embodiments, takes advantage of the properties of the parenchyma cells in which the sugars and sugar alcohols are contained in the almond casings. Some impurities, such as colored bodies and tannins are contained in these cells, but at a higher concentration in the cell wall and membrane structures. An objective of the present invention is to keep as large a number of cells as possible intact, since the sugars and sugar alcohols can easily pass through these membranes and walls to be recovered, while the recovery or removal of the colored bodies and the tannin is a function of more complex physical and chemical conditions. It is better to remember as much as possible
these last substances in the cells of the envelope than having to extract them later as impurities.

Thus, the almond husks themselves provide, already at the source of the sugars and sugar-alcohols, a means of excluding from the raw juice a significant proportion of impurities which would have to be removed subsequently, which improves still the proposed process. The collection of sugars, sugar alcohols and other materials in such a cell is believed to be remarkable, and the present invention can very advantageously take advantage of the properties of the cell.

 there is therefore now a new use for a low-value by-product, almond husks, and a new market can be found for inositol made at an appreciably reduced cost price.

 It can be noted that about 50% of almond trees around the world are cultivated in the United States, almost entirely in the state of California, and almost always by irrigation.

Irrigation guarantees a good harvest and the uniformity, from one year to the next, of properties, in particular properties such as the chemical composition of the envelopes. This means that the content of inositol and reducing sugars in almond husks obtained by cultivation with irrigation will not vary much from one year to the next. We also note that around 25% of almond trees worldwide are cultivated in Spain, where most orchards are not irrigated. The inositol and sugar content of Spanish almond husks will therefore vary from a wet year to a dry year, and this variability can adversely affect the profitability of a properly designed chemical processing facility.

 By using almond husks as a source, the inventors have, for the first time in industrial use to their knowledge, obtained inositol itself rather than a precursor of inositol.

 To briefly describe the invention, it can be indicated that a process according to it begins with almond husks as raw material. The almond casings (or teguments) naturally contain a mixture of water-soluble sugars and sugar alcohols; The sugars of the monosaccharide and disaccharide types are sucrose, fructose and glucose, and the sugar alcohols are sorbitol and non sitol. First of all, the almond husks are soaked in water> then a raw juice is extracted, either by extraction with water against the current, or by alternating expression and soaking operations, either by a combination of the two types of operations. The raw juice, obtained in this way, is subjected to filtration to remove the particulate matter and it is discolored to remove the colored bodies which have escaped from the parenchyma cells.

 The solution thus obtained is a clean and discolored solution of carbohydrates containing some salts. Salts can be removed by ion exchange. This results in a carbohydrate solution which is neutral, colorless, salt-free and which contains mainly only sugars and sugar alcohols.

This solution is passed through a preferential adsorption column capable of separating inositol, sorbitol and sugars, in an order determined by the properties of the molecular sieve that is used for the preferential adsorption process.

 Finally, when inositol constitutes the product to be prepared, a dilute aqueous solution of inositol is obtained from preferential adsorption. This dilute aqueous solution is then concentrated and crystals of inositol are produced.

 According to preferred, but optional, characteristics of the present invention, the ion exchange is carried out in the form of a cation / anion exchange in a mixed bed, and the concentration of the inositol solution is carried out by a reverse osmosis and evaporation operation sequence, which is followed by crystallization, by temperature regulation or by difference in solubility, from a supersaturated solution.

 According to yet another characteristic, preferred but optional, of the invention, the extraction of the sugars and of the sugar alcohols can be carried out by operating under acidic conditions. Under these conditions, fewer colored bodies are likely to go into solution, since they are generally soluble in alkaline substances. In addition, the sucrose present in the almond husks will undergo a reversal of fructose and glucose, which increases the amount of fructose and glucose present in the resulting sweetening agent when it is collected as a by-product. . This contrasts sharply with the processing of cane sugar, where we intend to produce sucrose and avoid acidic conditions.

The invention will now be described in more detail, by way of non-limiting examples, with reference to the appended drawings in which
Figure 1 is a flowchart showing the preferred preferred embodiment of the invention
Figure 2 is a flowchart showing means for processing one of the by-products of the process of Figure 1; and
Figure 3 is a flowchart showing another technique for extracting sugars and sugar alcohols from almond casings.

 Almond husks are of little value in almond producing regions.

Usually they are obtained in a relatively dry and dehydrated state due to their storage conditions. They exist in relatively large pieces, which usually form about half of the original intact shell, although there may be have, of course, many smaller pieces and some of which could be called particles or particulate pieces. In any case, it is better not to reduce its size even further, in particular by any process which risks exerting tearing, crushing, breaking or shearing forces, because
o such processes can destroy cellular structures whose integrity can constitute an important advantage for the present process.

 A property of almond husks is that the substances of interest for the present invention, mainly inositol and secondly fructose, glucose and sorbitol, are contained in a cell of a type known as the cell of parenchyma. This cell has a membrane tending to concentrate sugars (fructose, glucose) and sugar alcohols (inositol and sorbitol).

However, this cellular structure and matrix also contains tannins, phenolic substances and colored bodies, which are inconvenient.

 The parenchyma cell is not destroyed by dehydration and its properties are largely restored when this cell is soaked in water. One takes advantage of this fact by operating in such a way as to extract the water-soluble sugars and sugar-alcohols from the cells, but so as to leave the cellular structure intact and thus to exclude from the current of products as many tannins, phenolic substances and colored bodies. as possible. They will then be discarded with the envelope residue, rather than requiring their removal by a later means of purification. This is why we exert on the cells as little violence as possible because, each time a cell is ruptured, tannins, phenolic substances and colored bodies will be released with the sugars and with the sugar alcohols.

 A preferred technique is extraction with water against the current. According to conventional extraction techniques with counter-current water, the coolest water comes into contact with the almond casings having the lowest residual concentration of sugars and sugar alcohols, and the more concentrated juice comes in contact with the envelopes having the greatest concentration of sugars and sugar alcohols.

When this operation is adjusted appropriately, it can give almost 95% sugar and sugar alcohol extraction without expression of the envelopes
o
it will often be desirable to remove at least some of the remaining sugars and sugar alcohols from the casings after extraction with counter-current water, but this is optional. Such a technique is represented in FIG. 1 where it can be seen that, after extraction with water against the current, the solids are subjected to an expression operation, the extract of which is added to the raw juice from extraction with water against the current, which is followed by another soaking and expression operation, the extract obtained also being introduced into the raw juice.

Since the residue of the envelopes may have to be subsequently dried for disposal, for further processing or for other uses, the expression intended for obtaining sugars and sugar alcohols often constitutes an economic operation to be carried out to improve the energy balance of the system.

 It is better to conduct the extraction at a high temperature, but not too high. The best temperature range is between about 600 and 800 C. Such temperatures will increase the rate of extraction by increasing the rates of diffusion and adsorption. At about 65 "C, the growth of fungi and yeasts will be at least retarded. Towards the upper end of this interval, proteins, starches denature and form precipitates, which is advantageous for the purification of the solution. sugars.

 In the expression operation, the parenchyma cells should be considered as sponges into which the membranes admit water to dissolve the sugars and sugar alcohols, and then to allow them to be expelled under pressure through the membrane. Color bodies, tannins and phenolic substances do not cross the membrane as easily, unless the membrane and the cellular matrix - are ruptured.

 Thus, an expression operation is used rather than crushing or grinding. Typical grape presses used for the first and second pressing of fine bunches are perfectly suited. A conventional press, having circular holes of about 1.0 mm in diameter, which is operated at a gauge pressure of about 0.4 Flua, applied gradually without shock, applying only forces compression without significant shear, can play this role very well.

The extraction can be carried out at acidifications which result quite simply from the contact of the water and the envelopes, at a pH equal to approximately 4 to 5. However, some advantages can be obtained if the extraction is carried out under conditions more acidic, for example at a pH between about 2.0 and about 3.5. As noted above, this can result in a potentially beneficial reversal of sucrose to fructose and glucose. If we use -de
phosphoric acid for acidification, this can result in significant additional benefits. Because if you use calcium oxide (lime) to neutralize the raw juice, it results in a pH between 6.0 and 8.0, a precipitate of calcium phosphate. calcium and phosphate from the almond casings but, since this precipitate is flocculent, it attracts a certain number of impurities like colored bodies, which contributes to the clarification and discoloration of the solution.

 The raw juice from the extraction with water against the current, with or without the extracts from the expression operation, is then conveyed to coarse filtration. Before the coarse filtration, it is possible, as a useful step, to keep the juice for a moment in a sedimentation and precipitation tank, in particular if specific agents for complexing colored bodies and impurities have been added. coarse filtration consists of removing large particulate matter and foreign bodies, which are inevitably found in agricultural operations4 as well as pieces of almond husks that have escaped any previous sieving and, of course, the floc calcium phosphate containing trapped impurities if lime was used for neutralization. This gives a raw juice relatively free of particulate matter which is then subjected to ultrafiltration. The purpose of ultra-filtration is to carry out a fine elimination of particulate matter, to ensure clarification and sterilization of this solution.

 The solution then contains sugars and sugar alcohols, other mono- and polysaccharides in trace amounts, and some lost colored bodies. Its sugar concentration will be around 15 Brix (roughly 25prix in total).

 The ultra-filtration can be carried out using any fine ultra-filter, for example the "Romicon" material with hollow fibers having a flow rate of at least about 10.18 l / dm 3 / day. For this, any ultrafiltration medium which tends to remove proteins, starches and tannins polymerized with high molecular weight is suitable.

 I1 exist chemicals with a role of complexation of the colored bodies, cited above, which can facilitate this removal when they are added upstream of the ultra-filter.

These are generally high molecular weight polyacrylamides, low cationic and charged cation compounds, and other natural and synthetic polyelectrolyte materials.

 The product of the ultra-filtration stage is a clarified and shiny juice of purified sugars, with a very light color. Before performing the more complicated separation steps, it is better to subject the solution to a final fine discoloration by passing it through an adsorbent and bleaching material, such as a Rhom & Haas IRC-958 ion exchange material, or activated charcoal. This removes most of the residual color, which could later contaminate the product or make separation excessively difficult. The product of this bleaching step is a clear and discolored solution of carbohydrates1 containing some salts, such as sodium and potassium salts, hydrochloric, sulfuric, phosphoric acids and organic acids.

 It is desirable to remove the salts in order to optimize a subsequent separation technique and also in order to meet the specifications for the product. Mixed materials can be used with an ion exchange role, but it is better to pass the solution successively through a cation exchange material and then through an anion exchange material. Any suitable ion exchange material can be used for this. In the cation exchange column, hydrogen is released, however, the exchange material acquires sodium or potassium and the solution becomes more acidic. In the anion exchange column, there is release of the hydroxyl ion which reacts with the previously released hydrogen, removing anions such as chlorides and sulfates. This gives a neutral and colorless solution of carbohydrates without salt, the carbohydrates (or carbohydrates) in this case being the aforementioned sugars and sugar alcohols.

 The objective of the process being to produce inositol, it now becomes necessary to separate it from fructose, glucose and sorbitol. The present inventors have discovered that "molecular sieves can be used successfully to separate certain sugars and sugar alcohols from each other. A" molecular sieve "is defined herein as a substance which preferentially adsorbs one or more compounds of 'a solution such that one of the compounds to be recovered moves faster or slower than the others. By applying appropriate conditions of synchronization, duration and flow, the desired compound can be recovered. “Are they unaware of any previous recovery, used or usable on a commercial scale, of inositol from solutions containing other sugars and sugar alcohols.” Currently preferred molecular sieves are zeolites.

 The zeolitic molecular sieves (hereinafter called "zeolites") are crystalline aluminosilicates which have a three-dimensional framework structure and which contain exchangeable cations. The number of cations per unit cell is determined by its silica to alumina ratio and the cations are distributed in the channels of the zeolite framework. Carbohydrate molecules can penetrate the channels of the zeolite by diffusion and can then interact with the cation and be adsorbed on cations. The cations are in turn attracted by the alumino-silicate framework which constitutes a gigantic anion with multiple charge.

 The selectivity of adsorption of zeolite depends on the concerted action of the intensity of the electrostatic field, the radius of congestion of the cations, the size of the channels, the shape of these channels and the spatial distribution and density of cations. Since steric effects play a major role, the adsorption selectivities of a zeolite are highly unpredictable.

 Therefore, it cannot be expected that any zeolitic molecular sieve will work most advantageously to adsorb inositol. The present inventors have learned that the NaX, BaX and BaY zeolites adsorb inositol significantly more strongly than sucrose, fructose, glucose or sorbitol, and that they are particularly suitable for recovering inositol from a solution of mixtures of these compounds.

 Zeolite Y and the process for its manufacture are described in detail in US-A-3,130,007 (D.W. Breck, 1954). Zeolite X and the process for its manufacture are described in detail in US-A-2,882,244 (R.M. Milton, 1959). The accounts of these two patents are incorporated herein by reference.

 Type X and type Y zeolites, useful in the present invention, are those whose zeolitic cations are mainly sodium, barium, or calcium, which means that these zeolites may contain a minor amount of another cation as long as the zeolite is capable of effecting the desired separation. For example, it is possible to prepare, by known techniques, from a zeolite comprising sodium, introduced for example by exchange, zeolites into which calcium or barium has been introduced by exchange, and the product may contain a minor amount. sodium and still be useful in the present invention. Likewise, other cations, such as potassium, can be added in small amounts to the zeolites, or else be present as impurities without detracting from the usefulness of these zeolites in the present invention. More particularly, it is preferred that the specified cation satisfies by electrovalence at least approximately 50% and better still at least approximately 70%, on the basis of the charge equivalents, of the tetrahedra of A104 of the type X or type Y zeolite.

 In order to separate the inositol and / or sorbitol from the other carbohydrates of the almond husk liquid extract by the process of the present invention, a bed of a zeolitic agent is preferably loaded with adsorption products. solid adsorption, the non-adsorbed mixture or raffinate is removed from this bed and then desorbed, using a desorption agent, inositol and / or sorbitol Xadsorbed by the adsorbent zeolite. adsorption agent can, if desired, be contained in a single bed, in several beds, in which conventional techniques of alternating operation of the beds are used or in an apparatus of the countercurrent type simulating one or more moving beds, according to zeolite and depending on whether the adsorption relates to inositol and / or sorbi tol. Thus, a chromatographic graphic elution method can be used (such as that described in US Pat. No. 3,928,193, the description of which is here incorporated by reference) to recover each Qes five aforementioned carbohydrates under pure form, which includes inositol. As adsorbent zeolites, BaX, BaY, NaX and CaX types can be used. CaY cannot be used alone, because it adsorbs sorbitol better and, roughly also, it adsorbs inositol and fructose.

The separation of inositol from fructose must be carried out by a second bed, which may contain any of the CaX, NaX, BaX or BaY types.

 A preferred method for practicing the process of the present invention is separation by a chromatographic column. In this process, a feed solution (for example extract of almond envelopes) is injected for a short time at the top of a column and eluted with water by passing the column through. top to bottom. As the mixture travels through the column, a chromatographic separation leads to an area enriched more and more in adsorbed carbohydrates. The degree of separation increases as the mixture goes further down the column until a desired degree of separation is obtained.

We can then connect the tributary of the column to a receiving device which collects a pure product. Then, during the period in which a mixture of carbohydrates emerges from the column, the tributary can be directed to a "mixed product receptor". Then, when the area of adsorbed carbohydrate emerges from the end of the column, the tributary can be directed to a device for receiving this product.

 As soon as the chromatographic strips have penetrated deep enough into the column, a new quantity of material is introduced at the entrance of the column and the entire cycle of operations is repeated. The mixture, which leaves the end of the column between the moments of appearance of the pure fractions, is recycled to the feed and it crosses the column again, until extinction.

 The degree of separation of the ridges as they pass through this chromatographic column will increase with increasing length of the column. Therefore, one can provide or design a column of sufficient length to ensure to any desired degree the separation of one from the other of the two constituents.

 I1 is therefore possible to implement such a method so as to essentially involve no recycling, to food, of an unseparated mixture. However, if high purities are required, such a high degree of separation may require exceptional column length. In addition, as the constituents are eluted by passage through the column, their average concentrations gradually decrease. If carbohydrates are eluted with water, this may mean that the product streams will be more and more diluted with water, so it is highly likely that an optimal process (to obtain high degrees of purity of the constituents) implies the use of a much shorter column (than would be necessary for a complete separation of the ridges) and also involves separating the portion of the effluent containing the mixture of ridges and to recycle it to food, as indicated above.

NaX is also an adsorbent particularly suitable for the recovery of inositol, due to its remarkably high selectivity for the adsorption of inositol. Although its carrying capacity is not as high as BaX and BaY, the desorption of inositol from
NaX is faster than in the case of BaX and BaY. So,
NaX can be used for a separation process with a shorter cycle time than BaX and BaY, and will be suitable for both a fixed bed process and a process simulating one or more moving beds.

 The most effective desorption agent is water, which of course gives a relatively dilute solution of inositol. This solution must be concentrated in order to be able to economically recover inositol. Any suitable process can be used for the removal of water, such as reverse osmosis and evaporation techniques. The resulting solution is concentrated to a value between 50% and 95% (w / v) at a temperature below 100 "C, so that the resulting inositol solution is supersaturated.

 The hot supersaturated solution is conveyed to a crystallization vessel ("crystallizer") in which it is cooled. The inositol crystals will separate by precipitation and can be easily removed, while the remaining and concentrated solution of inositol can be recycled to the evaporator.

 It is better to maintain well below 10.0 the numerical value of the pH of the solution which is passed through the molecular sieve, in order to avoid the appearance of degradation products. If the aqueous solution is acidified with acetic acid to a pH of about 8.0, the separation of inositol appears to be improved. Likewise, a small amount of ethyl alcohol seems to facilitate separation, for reasons which are not fully known.

 In addition, after preparation of a relatively concentrated solution of inositol, better separation of the inositol crystals can be obtained by adding to this solution an organic solvent such as acetone or ethyl alcohol. According to known principles of solubility, combinations of water and organic solvent give significantly improved recovery of inositol.

 If it is further desired to separate fructose, glucose and sorbitol, Figure 2 shows a technique for this purpose, which begins with preferential absorption in a column, according to Figure 1. The solution of fructose, glucose and sorbitol is sent to a second preferential absorption column packed with a material such as a CaY zeolite, having the following sequence of selectivity sorbitol inositol ~ fructose> glucose> sucrose.

Thus, since the inositol is already removed from the solution, the extraction of sorbitol can be carried out easily. If the sucrose has been inverted, a fructose / glucose mixture will be a product, and sorbitol will be the other product.

 It has been previously stated that extraction with counter-current water may not always be preferred. In such a case, as shown in FIG. 35, two or three alternating operations of soaking and expressing the almond casings will give an extract which constitutes the whole of the raw food. This is then treated as indicated in Figure 1. The residual solids can be used in particular for animal feed.

In the preferred process described above, inositol was the first substance removed by the zeolite column, and the mixture of sorbitol and sugars remained to be
Discarded or for further treatment. Since zeolites have different rates of adsorption of dissolved substants and, for example, the zeolite CaY preferentially removes sorbitol, it is possible, and sometimes even desirable, to remove sorbitol first to remove it or discard or by-product title, and then separate the inositol from the sugars, using a different zeolite, such as that used in the preferred embodiment. It is entirely possible that sharper separations result from such a sequence of operations. Therefore, the present invention is not limited by the order in which the substances are removed or by the fact that these substances pass through the apparatus as raffinates or else are retained in the column for subsequent removal. The current. invention encompasses all of these operating sequences.

 It goes without saying that, without departing from the scope of the invention, numerous modifications can be made to the process, described and shown, for producing, by extraction of almond husks, sugars and sugar alcohols, in particular 1 ′ inositol.

Claims (17)

 1. Process for obtaining inositol from almond casings, characterized in that  a) the almond envelopes are soaked in water to dissolve the soluble carbohydrates contained in these envelopes and which dissolve the sugar alcohols: inositol and sorbitol and the sugars :: fructose and glucose, by dissolution. form a liquid extract  b) the undissolved matter is separated from this liquid extract  c) passing this liquid extract through one or more molecular sieves having the property of having different adsorption rates, this molecular sieve being made of a material in which the flow rate of one of these carbohydrates is plias slow or faster than the flow rate of other carbohydrates, so that at least one of these sugar alcohols can be separated from other carbohydrates using the molecular sieve.  2. Method according to claim 1, characterized in that the molecular sieve has the property of absorber preferably, among these carbohydrates, inositol which then has the slowest flow speed.  3. Method according to claim 19 characterized in that the molecular sieve has the property of absorbing, among these carbohydrates, preferably sorbitol which then has the lowest flow speed.  4. Method according to any one of the preceding claims, characterized in that the molecular sieve is a zeolite.  5. Method according to any one of claims 1 to 3, characterized in that step (a) is carried out in the form of an extraction with water against the current.  6. Method according to one of claims 1 and 2, characterized in that step (b) is carried out at least partially by expression of the quenched materials.  7. Method according to claim 6, characterized in that the expression is carried out with the minimum possible of shearing or shredding forces, so as to cause the least possible breakage of intact parenchyma cells.  8. Method according to one of claims 1 and 2, characterized in that, before step (c), the liquid extract is passed, in order to remove the ionic salts, through an exchange medium. cations and an anion exchange medium.  9. Method according to claim 1, characterized in that, before step (c), the liquid extract is passed, to clarify it, in an ultrafiltration device.  10. The method of claim 1, characterized in that concentrated by reverse osmosis the solution of inositol from step (c).  11. Process according to claim 10, characterized in that the concentration of inositol in the solution is further increased by evaporation, then the inositol is precipitated therefrom.  12. Method according to claim 11, characterized in that an organic solvent is added to the concentrated solution of inositol to facilitate precipitation.  13. Method according to claim 1, characterized in that, before step (c), lime is added to the extract.  14. Method for separating inositol, or sorbitol, from the other carbohydrates of an aqueous extract of almond husks, characterized in that this aqueous extract is passed through a molecular sieve consisting of one or more substances in which the speed of flow of inositol or sorbitol is appreciably slower or faster than the speed of flow of other carbohydrates, so as to separate, using the molecular sieve, inositol or sorbitol from other carbohydrates.  15. The method of claim 14, characterized in that the molecular sieve is a zeolite.  16. Method according to claim 15, characterized in that, inosito-l is the chosen material.  17. Method according to claim 15, characterized in that sorbitol is the chosen material.