WO2005077872A1

WO2005077872A1 - Cyclitol separation method

Info

Publication number: WO2005077872A1
Application number: PCT/US2005/004166
Authority: WO
Inventors: Ian Purtle; Wade Martinson; Aharon Eyal; Asher Vitner
Original assignee: Cargill, Incorporated
Priority date: 2004-02-09
Filing date: 2005-02-09
Publication date: 2005-08-25

Abstract

A method for the production of a cyclitol of increased purity is disclosed. The method includes extracting the cyclitol from a plant material with an extractant to form a cyclitol extract and forming a cyclitol source from the cyclitol extract and having a cyclitol purity P1. The method also includes (step b) contacting the cyclitol source with an extractant medium to form at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of P1 and P3. The method also includes subjecting the solvent-rich stream resulting from step (b) to an enrichment operation to form a cyclitol-enriched stream having a purity P4 and a cyclitol-depleted stream with a purity P5 so that P4 is greater than each of P2 and P5. A method for the production of a protein of increased purity and a cyclitol of increased purity is also disclosed. A method for increasing the purity of a cyclitol is also disclosed.

Description

CYCLITOL SEPARATION METHOD

CROSS-REFERENCE TO RELATED APPLICATIONS The following applications are cross-referenced and are hereby incorporated by reference in their entirety: U.S. Patent Application No. 60/543067 titled "PHENOLIC PURIFICATION SYSTEM" filed 09-Feb-2004 and U.S . Patent Application No. [to be determined] titled "PHENOLIC COMPOUND PURIFICATION" filed February 9, 2005 as Attorney Docket No. CGL04/0008/PCT; U.S. Patent Application No. 60/543066 titled "PHENOLIC PURIFICATION SYSTEM" filed 09-Feb-2004; U.S. Patent Application No. [to be determined] titled "PHENOLIC COMPOUND PURIFICATION" filed February 9, 2005 as attorney docket no. CGL04/0009PCT; U.S. Patent Application No. 60/630137 titled "MONOSACCHARIDE PRODUCTION SYSTEM" filed 22-Nov-2004; U.S. Patent Application No.: 60/557,204 titled "PROTEIN PURIFICATION SYSTEM" filed March 29, 2004. FIELD OF THE INVENTION The present invention generally relates to a cyclitol separation method. The present invention more particularly relates to a method for the separation of a cyclitol from a cyclitol source. The present invention still more particularly relates to a method for the production and isolation of a cyclitol from a plant source. The present invention more particularly relates to d-chiro-inositol (DCI) and its 3-O- methyl ether (d-pinitol). The present invention still more particularly relates to a method of preparing DCI from d-pinitol.

SUMMARY OF THE INVENTION

The present invention relates to a method for the production of a cyclitol of increased purity. The method includes extracting the cyclitol from a plant material with an extractant to form a cyclitol extract and forming a cyclitol source from the cyclitol extract and having a cyclitol purity PL The method also includes (step b) contacting the cyclitol source with an extractant medium to form at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of PI and P3. The method also includes subjecting the solvent-rich stream resulting from step (b) to an enrichment operation to form a cyclitol-enriched stream having a purity

P4 and a cyclitol-depleted stream with a purity P5 so that P4 is greater than each of P2 and P5.

The present invention also relates to a method for the production of a protein of increased purity and a cyclitol of increased purity. The method includes extracting soybean material with an extractant selected from at least one of water and aqueous solution to form a residual solid medium and an aqueous extract containing at least one protein, at least one cyclitol and at least one carbohydrate. The method also includes separating the aqueous extract into a protein stream and a cyclitol extract stream by at least one of membrane filtration and iso-electric precipitation and forming a cyclitol source from the cyclitol extract and having a purity PL The method also includes (step c) contacting the cyclitol source with solvent medium to form at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of PI and P3. The method also includes subjecting the solvent-rich stream resulting from step (c) to an enrichment operation to form a cyclitol-enriched stream with a purity P4 and a cyclitol-depleted stream with a purity P5 so that P4 is greater than each of P2 and P5, wherein the enrichment operation is selected from a group consisting of: i) removal of water present in the solvent-rich stream; ii) cooling the solvent-rich stream; iii) concentrating the solvent-rich stream by solvent removal; iv) changing the solvent composition in the solvent-rich stream to a less polar one; (v)

contacting the solvent-rich stream with a second cyclitol source; and (vi) combinations thereof.

The present invention also relates to a method for increasing the purity of a cyclitol. The method includes extracting a cyclitol from a plant material to form a cyclitol extract and forming a cyclitol source from the cyclitol extract and having a cyclitol purity PL The method also includes contacting the cyclitol source with a solvent medium to form at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of PI and P3, wherein: (i) PI is smaller than about 0.06; (ii) the cyclitol extract has a LogP in the range of about -1 to about +1; (iii) the polarity component of the Hansen solubility parameter of the solvent medium is in the range of about 5.5 to about 18; and (iv) the hydrogen bond component of the Hansen solubility parameter of the solvent medium is in the range of about 5 to about 23.

BACKGROUND Cyclitols are cycloalkanes containing one hydroxyl group on each of three or more ring atoms. Known cyclohexane-based cyclitols include those with six hydroxyl groups (i.e. 1,2,3,4,5 ,6-cyclohexanehexols) generically termed "inositols." Species of inositols differ in the position of the hydroxyl groups (i.e. above or below the plane of the molecule). Species of inositols include: cis-inositol (1,2,3,4,5,6/0), epi-inositol (1,2,3,4,5/6), allo-inositol (1,2,3,4/5,6) myo-inositol (1,2,3,5/4,6), muco- inositol (1,2,4,5/3,6), neo-inositol (1,2,3/4,5,6), scyllo-inositol (1,3,5/2,4,6) and D or L (ID or IL) chiro-inositol (1,2,4/3,5,6).

Of interest is D-chiro-inositol (DCI) and its 3-O-methyl ether, d- pinitol. D-pinitol is a cyclitol. D-pinitol is contained in plants such as Bougainviiles spectabilis, sugar pine and redwood. It is known to prepare DCI from d-pinitol.

A first such known system for preparing DCI from d-pinitol comprises isolating d-pinitol by extracting it from a plant (with a suitable solvent) and then de- methylating the d-pinitol with hydroiodic acid to produce DCI. However, such first known system for preparing DCI has several disadvantages including that extracting d-pinitol from the plant is cumbersome, and the process provides a relatively low yield of DCI. A second such known system for preparing DCI from d-pinitol comprises using as a starting material l-chloro-2,3-dihydroxycyclohexa-4,6-diene, and producing DCI therefrom through several reaction steps. A third such known system for preparing DCI from d-pinitol comprises using as a starting material a halogenobenzene and producing DCI therefrom through several reaction steps. However, such second and third known systems for preparing DCI have several disadvantages including requiring a stereo-specific synthesis - so the reaction efficiency is relatively low and the production cost of DCI is relatively high.

A fourth such known system for preparing DCI from d-pinitol comprises using as a raw material kasugamycin of high purity, heating it in 2N aqueous trifluoroacetic acid to hydrolyze the kasugamycin, passing the resulting reaction solution through a column containing a strongly basic ion-exchange resin and a column containing a strongly acidic ion-exchange resin, and then crystallizing DCI from the liquid effluent as finally flown out of the resin column by addition of ethanol to the effluent. However, such fourth known system for preparing DCI has several disadvantages including that it must use a very strong acid for the hydrolytic reaction of the kasugamycin, which may cause side reactions to take place upon cleavage of the kasugamycin molecules — thereby producing by-products and a relatively low yield of DCI. Accordingly, there is a need for a method of recovering cyclitol from a cyclitol source. There is also a need for a method for producing d-pinitol and DCI. There is also a need for providing concentrated and substantially purified d-pinitol for hydrolysis to yield DCI. There is also a need for a process for the separation of d- pinitol from various sources containing it in relatively high purity and concentration. There is also a need for a system and method for producing d-pinitol and DCI using sources other than soybean hulls (e.g. molasses of soy protein processing) that are readily available in large amounts. There is also a need for a method of recovery of d- pinitol, separation, and optionally conversion into DCI, in a way that allows recovery and purification of other co-extracted compounds (e.g. sugars, isoflavones, saponins, etc). It would be advantageous to provide a cyclitol separation method filling any one or more of these needs or having other advantageous features.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic diagram of a cyclitol separation method according to an exemplary embodiment of the present invention. FIGURE 2 is a schematic diagram of the cyclitol separation method of FIGURE 1 showing leaching and enrichment by solvent switching according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED AND OTHER EXEMPLARY EMBODIMENTS Referring to FIGURE 1, a cyclitol separation method is shown according to an exemplary embodiment. According to a preferred embodiment of the cyclitol separation method, the cyclitol is d-pinitol and D-chiro-inositol (DCI) is obtained by hydrolysis of the d-pinitol to form DCI and methanol. The cyclitol separation method allows for relatively high yield recovery and purification of d-pinitol from sources other than the hulls of soybeans and which are readily available (e.g. molasses of soy protein processing), according to a preferred embodiment.

According to one embodiment the cyclitol separation method comprises the steps of: a) extracting a cyclitol from a plant material to form a cyclitol source having a cyclitol purity PI; b) contacting the cyclitol source with a solvent medium to form a system with at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with reduced cyclitol purity P3, so that P2 is greater than each of PI and P3; c) subjecting the solvent-rich stream to an enrichment operation to form a cyclitol-enriched stream with purity P4 and a cyclitol-depleted stream with purity P5 so that the purity of the cyclitol-enriched stream is greater than both that of the cyclitol-depleted stream and that of the solvent-rich stream wherein the cyclitol enrichment operation comprises at least one of: (i) removal of at least a portion of the water present in the solvent-rich stream (For example, removing a fraction of the water is sufficient. Preferably, at least about 10% of the water is removed. Alternatively, the amount of water to be removed is such that on removal, the water activity in the solvent-rich stream decreases by at least about 0.05. Water removal could be done, for example, by suitable molecular sieves); (ii) cooling the solvent-rich stream (cooling is suitable to be at least about 5 degrees C, preferably at least about 10 degrees C, preferably at least about 15 degrees C); (iii) concentrating the solvent-rich stream by solvent removal (e.g. by removing at least about 5% of the solvent, preferably less than about 10% of the solvent, preferably less than about 20% of the solvent); (iv) changing the solvent composition in the solvent-rich stream to a less polar solvent (e.g. decreasing at least one of the polarity component of the Hansen solubility parameter and the hydrogen-based component of the Hansen solubility parameter by at least about 0.05, suitably 0.1, suitably 0.2); and (v) contacting the solvent-rich stream with the cyclitol source (e.g. similar to the contacting of step (b) except that it is done with the solvent-rich stream rather then with the fresh extractant/solvent); and (vi) combinations thereof.

According to a preferred embodiment of cyclitol separation method, the process includes the further step of recovering components of the cyclitol-depleted stream for commercial use.

According to a preferred embodiment of the cyclitol separation method, the cyclitol is d-pinitol.

One step of the cyclitol separation method may involve extracting cyclitol from a plant material to form a cyclitol extract. According to a preferred embodiment, the plant material is soy. Thus, as non-limiting examples, the plant material may be a soybean hull or the plant material may include de-fatted soybean meal, soy flakes, de-fatted soybean flakes and de -fatted soybean flour. Referring to the extraction step, the extractant used in the extracting of step (a) includes at least one of water, aqueous solution, alkali aqueous solution, acid aqueous solution, a polar organic solvent, mixtures of organic solvents and mixtures of organic solvents and water according to a preferred embodiment. In the extraction step the extractant has a LogP in the range of about -1 to about +1 according to a preferred embodiment.

In the contacting cyclitol source step (b), the cyclitol source is contacted with a solvent medium according to a preferred embodiment. The cyclitol source may be formed from the cyclitol extract by at least one treatment such as removing a solvent from the solution, membrane filtration, ion-exchange, hydrolysis of galactosyl-d-pinitol, glactosyl-DCI and other sugar ethers of d-pinitol and DCI, adsorption, fermentation of a carbohydrate and pH adjustment according to any preferred or alternative embodiment.

The concentration of some of the impurities in the extract approaches saturation according to a preferred embodiment. During the removal of solvent, a precipitate is formed, which precipitate contains those impurities. That precipitate is preferably removed from the solution before reaching the concentration at which the cyclitol precipitates out. Optionally, precipitation of impurities is facilitated by adding to the extract a non-solvent according to an alternative embodiment. Part of the d-pinitol and DCI in various sources, including the soy ones, may be present as sugar ethers. Those are preferably hydrolyzed to liberate d- pinitol or DCI before step (b) or simultaneously with it. Such hydrolysis could be catalyzed chemically (e.g. by acid treatment) or enzymatically (e.g. by using galactosidases). According to a particularly preferred embodiment, the chemically catalyzed hydrolysis requires conditions such as high concentration of an acid, high temperature and several hours of reaction.

Membrane filtration removes proteins and polysaccharides according to a preferred embodiment. Various commercial ultra-filtration and nano-filtration membranes are suitable according to any preferred or alternative embodiment. Ion- exchange may remove cations and anions as well as compounds charged at given pH levels (e.g. proteins and amino acids) according to a preferred embodiment. Adsorption (e.g. on active carbon or a decolorizing resin) may remove colorants and hydrophobic impurities according to a preferred embodiment. Adjustment of pH to about the iso-electric point of proteins in the extract leads to their precipitation and removal from the source according to a preferred embodiment. Such proteins are available for further utilization (e.g. as feed ingredients) according to a preferred embodiment.

Some of the carbohydrates in the extract could be fermented, preferably into selectively separable products (e.g. volatile ones such as ethanol) according to an alternative embodiment. According to another alternative embodiment, fermentation is conducted on carbohydrates present in the solvent-poor stream of step (b) and/or on the cyclitol-depleted stream of step (c). Optionally, those streams are treated before fermentation (e.g. by solvent removal or,by addition of suitable nutrients for the microorganisms) according to another alternative embodiment. In those options, enzymatic or chemical hydrolysis is preferably conducted in order to convert oligosaccharides into monosaccharides or disaccharides that are more available as fermentation feedstock. Such hydrolysis may be conducted simultaneously with the hydrolysis of the cyclitol sugar ethers according to any preferred or alternative embodiments.

According to a preferred embodiment, the fermentation product is ethanol, which is used as a make up for the solvent used in steps (a), (b), (c) or a combination of those.

Steps (a), (b) and (c) of the cyclitol separation method may result in high degree of purification without necessarily resorting to the above-listed purification methods. According to an alternative embodiment, such purification methods could be used for final purification of the cyclitol-enriched stream.

According to a preferred embodiment, the cyclitol source also contains proteins and carbohydrates. Exemplary cyclitol sources include soy whey, soy solubles, molasses of protein concentrate production and molasses of protein isolate production.

According to a preferred embodiment, the source is dried before the contacting in step (b) to form a dried source, preferably containing less than about 5 percent water and preferably the dried source is ground before the contacting in step (b).

Referring now to step (b) of the cyclitol separation method, it is to be noted that in preferred embodiments the water content of the system of step (b) is smaller than about 10 percent, and the contacting step of step (b) is a solid-liquid contact and involves an operation such as mixing, stirring or sonication.

According to an alternative embodiment, the extract is concentrated to form a highly concentrated aqueous solution, as close as feasible to saturation in the cyclitol, and the contact with the solvent is a liquid-liquid contact.

Concentrated feed streams allow the use of extractants that have full miscibility in water (e.g. iso-propanol, propanol, tert-butanol, etc.). The relatively high concentration of solutes decreases the solubility of those solvents in the aqueous solution.

The solvent-rich stream of step (b) can be further purified before step (c) according to a preferred embodiment—one way of doing so is through liquid-liquid contact. The solvent-rich stream is washed with small amounts of water several times to remove the more hydrophilic impurities and increase the purity of d-pinitol in the solution according to this embodiment. In those cases wherein water addition does not form two phases, a small amount of hydrophobic solvent may be added to the solvent-rich stream according to an alternative embodiment. According to a particularly preferred embodiment, the contacting of step (b) is conducted at a temperature of between about 30 degrees Celsius and about 80 degrees Celsius, and most preferred is a temperature of between about 40 degrees Celsius and about 70 degrees Celsius. In carrying out the contacting step (b), it is preferred to use solvents where the polarity component of the Hansen solubility parameter of the solvent of step (b) is in the range of about 5.5 to about 18. According to an alternative embodiment, the hydrogen bond component of the Hansen solubility parameter of the solvent of step (b) is in the range of about 5 to about 23.

According to a particularly preferred embodiment, step (b) is carried out utilizing a solvent such as methanol, ethanol and mixtures thereof.

According to a preferred embodiment, the solvent-poor stream includes at least one of solids, solid slurries, and a concentrated aqueous solution. According to a particularly preferred embodiment, the ratio between

P2 and P3 is greater than about 2: 1, and the ratio between P4 and P5 is greater than about 3:1.

According to a preferred embodiment, the ratio between the cyclitol amount in the solvent-rich stream and the cyclitol amount (by weight) in the solvent- poor stream is greater than about 1.5:1, and more suitably the ratio between the cyclitol amount in the solvent-rich stream and the cyclitol amount in the solvent-poor stream is greater than about 4:1

According to an alternative embodiment of the cyclitol separation method, there is provided a method for the production of purified protein and of purified cyclitol, which method comprises the steps of: a) extracting soybean de-fatted flakes with a solvent selected from a group consisting of water and aqueous solutions to form a residual solid medium and an aqueous extract containing at least one protein, at least one cyclitol and at least one carbohydrate; b) separation of the aqueous extract into a purified protein stream and a cyclitol extract stream by membrane filtration or iso-electric precipitation wherein the cyclitol extract comprises a cyclitol source having a cyclitol purity PI; c) contacting the cyclitol source with a solvent medium to form a system with at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with reduced cyclitol purity P3 so that P2 is greater than both PI and P3; d) subjecting the solvent-rich stream to an enrichment operation to form a cyclitol-enriched stream with purity P4 and a cyclitol-depleted stream with purity P5 so that the purity of the cyclitol-enriched stream is greater than both that of the cyclitol-depleted stream and that of the solvent-rich stream wherein the enrichment operation comprises at least one of: i) removal of water present in the solvent-rich stream; ii) cooling the solvent-rich stream; iii) concentrating the solvent-rich stream by solvent removal; iv) changing the solvent composition in the solvent-rich stream to a less polar one; v) contacting the solvent-rich stream with the cyclitol source; and (vi) combinations thereof. According to an alternative embodiment of the cyclitol separation method, there is provided a method for the production of purified protein and of purified cyclitol, which method comprises the steps of: a) extracting soybean defatted flakes with a solvent selected from a group consisting of water and aqueous solutions to form a residual solid medium with increased protein concentration and an aqueous extract comprising at least one cyclitol and at least one carbohydrate; b) contacting a cyclitol source, which source results from the extract and has a given cyclitol purity, PI, with a solvent medium to form a system with at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with reduced cyclitol purity P3 so that P2 is greater than both PI and P3; c) subjecting the solvent-rich stream to an enrichment operation to form a cyclitol-enriched stream with purity P4 and a cyclitol-depleted stream with purity P5 so that the purity of the cyclitol-enriched stream is greater than both that of the cyclitol-depleted stream and that of the solvent-rich stream wherein the enrichment operation comprises at least one of: i) removal of water present in the solvent-rich stream; ii) cooling the solvent-rich stream; iii) concentrating the solvent-rich stream by solvent removal; iv) changing the solvent composition in the solvent-rich stream to a less polar one; v) contacting the solvent-rich stream with the cyclitol source; and (vi) combinations thereof.

According to an alternative embodiment of the cyclitol separation method, there is provided a method for the purification of a cyclitol, which method comprises the steps of: a) extracting a cyclitol from a plant material to form a cyclitol extract having a cyclitol purity PI; b) contacting the extract with a solvent medium to form a system with at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of PI and P3 wherein: i) PI is smaller than about 0.06; ii) the extractant has a LogP in the range of about -1 to about +1 ; iii) the polarity component of the Hansen solubility parameter of the solvent is in the range of about 5.5 to about 18; and iv) the hydrogen bond component of the Hansen solubility parameter of the solvent is in the range of about 5 to about 23.

According to a preferred embodiment, the cyclitol-enriched stream is further purified by a treatment such as membrane filtration, ion-exchange, adsorption, chromatographic separation, solvent extraction or crystallization of impurities.

According to an alternative embodiment, the cyclitol-enriched stream is further treated to form a precipitate with a purity, P6 wherein P6 is greater than P4. According to a preferred embodiment, the precipitation is induced by cooling, evaporation of solvent or addition of a non-solvent. Cyclitol crystallization nuclei are used according to a preferred embodiment

According to an alternative embodiment, the cyclitol-enriched stream is further purified (e.g. by active carbon treatment).

According to another alternative embodiment, the cyclitol is chemically modified to form a derivative of lower solubility. According to a preferred embodiment, the cyclitol in the cyclitol-enriched stream is d-pinitol and the d-pinitol is hydrolyzed to form DCI. Experiments have shown that DCI solubility in solvents suitable for the present invention is significantly lower compared with that of d-pinitol, so that hydrolysis in solution approaching saturation in d-pinitol produces DCI, which precipitates out. Furthermore, it has now been found that the solubility of DCI is more dependent on temperature than the solubility of d-pinitol that makes separation of DCI even easier. See, e.g. Example 6.

According to a particularly preferred embodiment, the method comprises the further step of recovering components of the cyclitol-depleted stream (e.g. for commercial use).

Referring to step (c)(iv) as set forth above, it is to be noted that changing the solvent composition in the solvent-rich stream to a less polar one can be conducted by adding to the solution a less polar solvent, which may be combined with distilling out part of the solvent used in step (b) prior to the addition, simultaneously with it or after it according to an alternative embodiment. If a binary solvent is used in step (b), the changing may be done by fractional partial distillation, if out of the two solvents the more polar one is the lighter one as in the case of ethanol/methanol mixture according to alternative embodiments. Such fractional partial distillation could be combined with the addition of a less polar solvent according to an alternative embodiment. Such less polar solvent may also be a binary solvent with higher proportion of the less polar component according to an alternative embodiment. Referring to Figure 2, such a process may be carried out by using ethanol/methanol mixture of about 25/75 as the solvent in step (b) to form the solvent- rich stream, partial evaporation to convert the solvent ratio to an ethanol/methanol mixture of about 45/55, addition of a solvent with ethanol/methanol mixture of about 75/25 and cooling to precipitate the cyclitol-depleted stream according to alternative embodiments. Referring further to Figure 2, solvent 1 isEthanol / methanol mixture having wt/wt ratio of 1/3, solvent 2 is a Ethanol / methanol mixture having wt/wt of 1/6, and solvent 3 is a Ethanol / methanol mixture having wt/wt ration of 1.5/1 according to an exemplary embodiment. According to a preferred embodiment, the increase in the hydrophobic nature of the solvent is done gradually to prevent co-precipitation of product with the cyclitol-depleted solids.

According to an alternative embodiment, enrichment of the solvent- rich stream may be done by crystallization of sucrose to leave a more purified solution. Such crystallization is preferably facilitated by the addition of sucrose crystallization nuclei.

According to an alternative embodiment, the cyclitol-enriched stream can be further purified by methods such as membrane filtration (ultra or nano- filtration membranes) to remove high-molecular-weight impurities, ion-exchange to remove impurities that preferably adsorb to ion-exchangers, adsorption of impurities on active carbon or decolorizing resins, fermentation of a carbohydrate, pH adjustment and chromatographic separation.

While embodiments of the invention will now be described in connection with certain examples so that aspects thereof may be more fully understood and appreciated, it is not intended to limit the invention to these particular examples. EXAMPLES Example A - Preparation of Cvclitol Source

De-fatted soy flakes were extracted with water to form a cyclitol extract. The cyclitol extract was ultra-filtered to remove dissolved proteins, dried in an oven overnight at 70 degrees Celsius, ground and sieved on a 500-micron screen to form a relatively uniform, fine powder, cyclitol source. The ratio between d-pinitol and other solids in the source (defined as PI in this Example) was 0.0116 or 1.16%.

Example 1

Samples of the cyclitol source of Example A and various solvents were introduced into sealed vials. The vials were shaken in a water bath. The vials were removed from the bath after 72 hours for analysis. The results are presented in Table 1 along with some results of pure d-pinitol solubility.

Table 1

where MeOH - methanol, EtOH - ethanol, PrOH - n-propanol, BuOH - n-butanol

According to these results, d-pinitol was selectively recovered from the source at high selectivity (P2/P3) of 10. That relatively high selectivity was found even though the initial purity of the source was relatively low (i.e. PI of about 1 percent). Example_2

Samples of the cyclitol source of Example A and methanol were introduced into sealed vials. The vials were shaken in a water bath at 60 degrees Celsius. The vials were removed from the bath at various time intervals for analysis. The results are presented in Table 2.

Table 2

The results indicate that the kinetics of d-pinitol leaching from the source as prepared was relatively high.

Example 3

A sample of cyclitol source from Example A was contacted with twice its weight of ethanol containing various water concentrations at 45 degrees Celsius for 105 minutes. The liquid was separated and analyzed. The concentrations of d-pinitol and the d-pinitol/sucrose high performance liquid chromatographyHPLC peak ratio in the solvent-rich solutions are presented in Table 3.

Table 3

Relatively high selectivity in d-pinitol separation from sucrose was demonstrated.

Example 4

Solutions containing 99% organic solvent (methanol, ethanol or a mixture of those and 1 wt% water were tested. A solution and a sample of cyclitol source from Example A, at 2:1 weight ratio respectively were introduced into vials. The vials were shaken at 45 degrees Celsius for 1 hour. Samples were taken for HPLC analysis. The results are presented in Table 4.Table 4

*Calculated by dividing the d-pinitol content in the solvent-rich solution by that in the dried cyclitol source sample.

Example 5

A methanolic solution containing 1 wt% water and a sample of cyclitol source of Example A were introduced into a vial at 2: 1 weight ratio. The vial was shaken at 45 degrees Celsius for 1 hour. The solution was filtered and re-contacted with a fresh sample of the cyclitol source of Example A at same ratio, temperature, and time. Samples were taken from the solvent-rich solutions and from the solids of the two contacts for analysis. The results are presented in Table 5.

Table 5

The results for the first contact show P2 greater than both P3 and PL The second contact with the source increased the purity of the d-pinitol in the solvent- rich solution. The results show that P4 was greater than both P5 and P2.

Example 6 The solubility of d-pinitol is compared in Table 6 with that of DCI at two temperatures and in various solvents.

. Table 6

The results show that compared with pinitol solubility, DCI solubility was smaller and was more sensitive to temperature in the tested solvents. Hence, hydrolysis of pinitol solutions of sufficiently high concentration resulted in DCI crystallization, particularly when conducted at relatively low temperatures

Example 7

200 gram soy hulls and 800 gram of an ethanol :water (80:20 ratio) solution were introduced into a flask. The flask was shaken at 50 degrees Celsius for 4 hours. The solution was filtered and the hulls were washed 2 times with the same solvent. The three solutions were collected together and concentrated. PI of the concentrated solution was 20 wt% (weight cyclitols/weight solids).

The concentrated solution was equilibrated with propanol. Samples from the two phases were analyzed for d-pinitol and solids. The results are presented in Table 7. Table 7

This Example demonstrates purification of d-pinitol in a liquid-liquid contact.

Example 8

2 grams aqueous solution containing 40 wt% sucrose and 2 wt% d- pinitol (Pl= 5%) were introduced to several vials. 1 gram solvent was added to each vial. The vials were shaken at 50 degrees Celsius for 2 hours. Samples were taken from the two phases in each vial for analysis. The results are presented in Table 8.

Table 8

* distribution coefficient is the ratio between d-pinitol concentration in the solvent- rich phase and its concentration in the aqueous phase.

Example 9

Example 9.1

60 grams solvent containing 74 weight percent MeOH+25%EtOH and 1% water, and 30.65 grams of a cyclitol source were contacted in a flask for 1 hour at 60 degrees Celsius ^' The cyclitol source and the solvent-rich solution were analyzed. The results are presented in Table 9. Table 9

Example 9.2

50.964 grams of the solvent-rich solution from Example 9.1 were concentrated at 40 degrees Celsius. The final weight of the solution was 35 grams. A precipitate was formed. The precipitate was washed with cold ethanol and dried. A sample of the washed precipitate was analyzed and found to have P of 0.5%. This precipitate was depleted in d-pinitol so that the concentrated solvent-rich solution was enriched in d-pinitol.

Example 9.3

A molecular sieve was added to the solvent-rich solution from Example 9.2 in 3 portions of 2 grams each, while shaking, in order to adsorb water. A dark precipitate depleted in d-pinitol was formed upon the molecular sieve. Thus, drying enriched the solvent solution in d-pinitol.

The sieve particles were washed with 18.49 grams solvent containing 25% EtOH and 75% MeOH. The solution was added to the concentrated leaching solution.

Example 9.4 The ethanol/methanol ratio in the solvent-rich solution from the previous steps (i.e. Example 9.3) was gradually increased as described in the following procedure: The weight of the sample was 35.3 grams, the initial EtOHMeOH ratio was 0.35:0.65, and the water content was 0.66 wt%. A solution with EtOH: MeOH ratio of 1:1 was added to the solution, while shaking at 60 degrees Celsius. A solid precipitated out as fine particles. Similar treatments were repeated with two solutions containing EtOH:MeOH at ratios of 1.5:1 and 2.5:1, respectively. A solid precipitated out in both cases as fine particles.

A sample from the final solution was analyzed for ethanol/methanol ratio. The ethanol concentration in the solvent was 66 wt%. The precipitate formed in the process was filtered and analyzed.

The solution was concentrated at 50 degrees Celsius to a final weight of 35.5 grams. A sample was analyzed. The ethanol concentration in the solvent was 71 wt%. The composition of the final solution and of the precipitate are presented in Table 10.

Table 10

D-pinitol purity was increased in the various enrichment processes. The HPLC results indicate that the sucrose concentration in the enriched solution was very low. The impurities that precipitated out in the enrichment operations were very low in d-pinitol.

Example 10

1.25 grams solution was obtained by extracting a cyclitol source and enrichment through solvent switch, as in Example 9.4. 0.1 grams of d-pinitol were added to solution. The solution was shaken in a water bath at 50 degrees Celsius for 14 hours. The analyses of the solution before the addition of cyclitol and after its addition are presented in Table 11.

Table 11

D-pinitol added to the solution acted as crystallization nuclei and facilitated d-pinitol crystallization. * * *

The "Hansen solubility parameter" of a compound as used in this disclosure is the square root of its cohesive energy density - the energy of vaporization divided by the molar volume. The cohesive energy arises from contributions from the compound's polarity, H-bonding capability, and dispersion forces. The polarity and H-bonding components of the solubility parameters for many compounds can be found in sources such as CRC Handbook of Solubility Parameters and Other Cohesion Parameters by Allen F. M. Barton (see particularly sections 5.9 and 5.11) and by Molecular Analysis Pro software from ChemSW™ Inc. For other compounds, the solubility parameters can be estimated either based on similarity to known molecules or calculated according to group contribution as explained in textbooks or by suitable software as above. Parameters for mixtures are calculated from the parameters of the mixture components and from the relative content of each. The term "Log P" as used in this disclosure is the logarithm of compound partitioning coefficient between octanol and water. Log P data for many solvents are found in the CRC Handbook of Chemistry and Physics. Log P can also be determined by introducing water and octanol at similar amounts into a vessel where two phases will form. A small amount of the tested solvent (about one tenth of the amount of water is suitable) is added to the vessel, which is mixed to reach equilibrium. The solvent concentration in each of those phases is determined. Log P is the logarithm of the figure obtained by dividing the concentration of the solvent in the octanol-rich phase by that of the water-rich phase.

The term "purity" as used in this disclosure relates to the weight ratio between cyclitol and other components with a boiling point of greater than 120 degrees Celsius at atmospheric pressure. * * *

While the preferred and other exemplary embodiments illustrated in the drawings and described above are presently preferred, it should be understood that these embodiments are offered by way of example only. The invention is not limited to a particular embodiment, but extends to various modifications, combinations, and permutations.

Claims

CLAIMSWhat is claimed is:

1. A method for the production of a cyclitol of increased purity comprising: (a) extracting the cyclitol from a plant material with an extractant to form a cyclitol extract and forming a cyclitol source from the cyclitol extract and having a cyclitol purity PI; (b) contacting the cyclitol source with an extractant medium to form at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of PI and P3; and (c) subjecting the solvent-rich stream resulting from step (b) to an enrichment operation to form a cyclitol-enriched stream having a purity P4 and a cyclitol-depleted stream with a purity P5 so that P4 is greater than each of P2 and P5.

2. The method of Claim 1 wherein the enrichment operation comprises at least one of the following: (1) removal of water present in the solvent-rich stream; (2) cooling the solvent-rich stream; (3) concentrating the solvent-rich stream by solvent removal; (4) changing the solvent composition in the solvent-rich stream to a less polar one; (5) contacting the solvent-rich stream with a second cyclitol source as in step (b); and (6) combinations thereof.

3. The method of Claim 1 wherein the cyclitol source comprises at least one of d-pinitol, D-chiro-inositol, and inositols.

4. The method of Claim 1 wherein the plant material is a soybean plant.

5. The method of Claim 1 wherein the plant material is a soybean hull.

6. The method of Claim 1 wherein the plant material comprises at least one of a de-fatted soybean meal, a soybean flake, a de-fatted soybean flake, and a defatted soybean flour.

7. The method of Claim 1 wherein the extractant used in the extracting step comprises at least one of water, aqueous solution, alkali aqueous solution, acid aqueous solution, a polar organic solvent, mixtures of organic solvents, and mixtures of organic solvents and water.

8. The method of Claim 1 wherein the extractant has a Log P in the range of about -1 to about +1.

9. The method of Claim 1 wherein the cyclitol source is formed from the cyclitol extract by at least one of: removing a solvent from the solution, membrane separation, ion-exchange, hydrolysis of galactosyl-d-pinitol, hydrolysis of glactosyl- DCI, hydrolysis of other sugar ethers of d-pinitol and DCI, adsorption, fermentation of a carbohydrate and pH adjustment.

10. The method of Claim 1 wherein the cyclitol extract also contains at least one protein and at least one carbohydrate.

11. The method of Claim 1 wherein the cyclitol extract comprises at least one of soy whey, soy solubles, molasses of protein concentrate production, and molasses of protein isolate production.

12. The method of Claim 1 wherein the cyclitol source is dried before the contacting step.

13. The method of Claim 12 wherein the cyclitol source is ground before the contacting step or simultaneously with it.

14. The method of Claim 12 wherein the cyclitol source and the solvent medium have a total water content of less than about 10 percent.

15. The method of Claim 1 wherein the contacting of step (b) further comprises at least one of mixing, stirring, and sonication.

16. The method of Claim 1 wherein the contacting of step (b) is conducted at a temperature of between about 30 degrees C and about 80 degrees C.

17. The method of Claim 1 wherein the polarity component of the Hansen solubility parameter of the solvent medium of step (b) is in the range of about 5.5 to about 18.

18. The method of Claim 1 wherein the hydrogen bond component of the Hansen solubility parameter of the solvent medium of step (b) is in the range of about 5 to about 23.

19. The method of Claim 1 wherein the solvent-poor stream is a concentrated aqueous solution.

20. The method of Claim 1 wherein the solvent-poor stream comprises a slurry.

21. The method of Claim 1 wherein the ratio between P2 and P3 is greater than about 2:1.

22. The method of Claim 1 wherein the ratio between P4 and P5 is greater than about 3:1.

23. The method of Claim 1 wherein the ratio between the cyclitol amount in the solvent-rich stream and the cyclitol amount in the solvent-poor stream is greater ithan about 1.5:1.

24. The method of Claim 1 wherein the ratio between the cyclitol amount in the solvent-rich stream and the cyclitol amount in the solvent-poor stream is greater than about 4:1.

25. The method of Claim 1 wherein the cyclitol-enriched stream is further purified by at least one of membrane filtration, ion-exchange, adsorption, chromatographic separation, solvent extraction, crystallization of impurities or a combination thereof.

26. The method of Claim 25 wherein the cyclitol-enriched stream is further treated to form a precipitate with a purity P6 wherein P6 is greater than P4.

27. The method of Claim 26 wherein the precipitation is induced by at least one of cooling, evaporation of solvent, addition of a non-solvent and chemical conversion.

28. The method of Claim 26 wherein step (b) is carried out utilizing a solvent comprising at least one of methanol, ethanol, and mixtures thereof.

29. The method of Claim 26, comprising the further step of selectively recovering components of the cyclitol depleted stream.

30. The method of Claim 1 wherein P6 > P4 > P2 > PI > P3.

31. The method of Claim 30 wherein P2 > P5. 32. A method for the production of a protein of increased purity and a cyclitol of increased purity, which method comprises the steps of: (a) extracting soybean material with an extractant selected from at least one of water and aqueous solution to form a residual solid medium and an aqueous extract containing at least one protein, at least one cyclitol and at least one carbohydrate; (b) separating the aqueous extract into a protein stream and a cyclitol extract stream by at least one of membrane filtration and iso- electric precipitation and forming a cyclitol source from the cyclitol extract and having a purity PI; (c) contacting the cyclitol source with solvent medium to form at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of PI and P3; (d) subjecting the solvent-rich stream resulting from step (c) to an enrichment operation to form a cyclitol-enriched stream with a purity P4 and a cyclitol-depleted stream with a purity P5 so that P4 is greater than each of P2 and P5, wherein the enrichment operation is selected from a group consisting of: i) removal of water present in the solvent-rich stream; ii) cooling the solvent-rich stream; iii) concentrating the solvent-rich stream by solvent removal; iv) changing

30. The method of Claim 1 wherein P6 > P4 > P2 > PI > P3.

31. The method of Claim 30 wherein P2 > P5.

32. A method for the production of a protein of increased purity and a cyclitol of increased purity, which method comprises the steps of: (a) extracting soybean material with an extractant selected from at least one of water and aqueous solution to form a residual solid medium and an aqueous extract containing at least one protein, at least one cyclitol and at least one carbohydrate; (b) separating the aqueous extract into a protein stream and a cyclitol extract stream by at least one of membrane filtration and iso- electric precipitation and forming a cyclitol source from the cyclitol extract and having a purity PI; (c) contacting the cyclitol source with solvent medium to form at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of PI and P3; (d) subjecting the solvent-rich stream resulting from step (c) to an enrichment operation to form a cyclitol-enriched stream with a purity P4 and a cyclitol-depleted stream with a purity P5 so that P4 is greater than each of P2 and P5, wherein the enrichment operation is selected from a group consisting of: i) removal of water present in the solvent-rich stream; ii) cooling the solvent-rich stream; iii) concentrating the solvent-rich stream by solvent removal; iv) changing

28 the solvent composition in the solvent-rich stream to a less polar one; (v) contacting the solvent-rich stream with a second cyclitol source; and (vi) combinations thereof.

33. A method for increasing the purity of a cyclitol comprising: (a) extracting a cyclitol from a plant material to form a cyclitol extract and forming a cyclitol source from the cyclitol extract and having a cyclitol purity PI; (b) contacting the cyclitol source with a solvent medium to form at least one solvent-rich stream with an increased cyclitol purity P2 and at least one solvent-poor stream with a reduced cyclitol purity P3 so that P2 is greater than each of PI and P3, wherein: (i) PI is smaller than about 0.06; (ii) the cyclitol extract has a LogP in the range of about -1 to about +1; (iii) the polarity component of the Hansen solubility parameter of the solvent medium is in the range of about 5.5 to about 18; and (iv) the hydrogen bond component of the Hansen solubility parameter of the solvent medium is in the range of about 5 to about 23.

34. The method of Claim 33 wherein the solvent-rich stream with the increased cyclitol purity P2 is hydrolyzed to yield D-chiro-inositol.

35. The method of Claim 34 wherein the cyclitol source is formed by hydrolysis and wherein the hydrolysis is catalyzed chemically or enzymatically.

36. The method of Claim 35 wherein the cyclitol extract comprises at least one carbohydrate, and further comprising the step of fermenting the carbohydrate to form a fermentation product.

37. The method of Claim 36 wherein the fermenting is conducted on carbohydrates present in at least one of the cyclitol source, the cyclitol extract, the solvent-rich stream, the solvent-poor stream stream and the cyclitol-depleted stream.

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38. The method of Claim 36 wherein the carbohydrate comprises at least one disaccharide or oligosaccharide, and further comprising a step of enzymatic or chemical hydrolysis of the disaccharide or oligosaccharide into monosaccharides.

39. The method of Claim 38 wherein the hydrolysis is conducted simultaneously with hydrolysis of cyclitol sugar ethers.

40. The method of Claim 35 wherein the cyclitol extract is concentrated to form a highly concentrated aqueous solution, as close as feasible to saturation in the cyclitol, and the contact with the solvent medium is a liquid-liquid contact.

41. The method of Claim 33 wherein the cyclitol in the solvent-rich stream is d-pinitol and the d-pinitol is hydrolyzed to form D-chiro-inositol.

42. The method of Claim 41 wherein the enrichment operation comprises changing the solvent composition in the solvent-rich stream to a less polar one, comprising at least one of: (i) adding to the solution a less solvent and (ii) adding to the solution a solvent having a lower polarity than the solvent medium combined with distilling out part of the solvent medium used in step (b).

43. The method of Claim 41 wherein the enrichment operation comprises changing the solvent composition in the solvent-rich stream to a solvent having a polarity less than the solvent medium and wherein the solvent medium used in step (b) comprises at least two solvents, comprising fractional partial distillation to distill out a more polar solvent.

44. The method of Claim 43 wherein enrichment of the solvent-rich stream comprises crystallization of sucrose.

45. The method of Claim 44 wherein the crystallization is facilitated by the addition of sucrose crystallization nuclei.

46. The method of Claim 33 wherein the cyclitol is chemically modified to form a derivative of lower solubility.

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