WO1999049087A1

WO1999049087A1 - A process for fractionating soy molasses

Info

Publication number: WO1999049087A1
Application number: PCT/IL1999/000133
Authority: WO
Inventors: Avraham Baniel
Original assignee: Innova SA
Current assignee: Innova SA
Priority date: 1998-03-26
Filing date: 1999-03-08
Publication date: 1999-09-30
Anticipated expiration: 2000-09-26
Also published as: IL123846A; IL123846A0; AU3271599A

Abstract

A process for fractionating soy molasses, whereby successive fractions are obtained in which the global C/O ratio of compounds containing only carbon, hydrogen and oxygen atoms, is increased with each successive fraction, the process comprising carrying out a series of successive extractions effected by mixing molasses with a solvent to establish equilibrium, separating the resultant solvent phase from the aqueous phase, mixing a separated aqueous phase from a previous extraction with a further aliquot of solvent to establish equilibrium, separating the resultant solvent phase from the aqueous phase and recovering a product representing a fraction of soy molasses from each successive liquid extract by methods known per se, the solvent being selected from the group consisting of compounds containing only carbon, hydrogen and oxygen atoms, the compounds having a C/O ratio of at least 3 and having up to 6 carbon atoms.

Description

A PROCESS FOR FRACTIONATING SOY MOLASSES Technical Field

The present invention relates to a process for fractionating soy molasses.

Soy Molasses (SM) of acceptable stability contains <60% water and numerous solutes.

Background Art

There are numerous minor solutes and only a few major ones. Carbohydrates are preponderant, totaling -60% on dry solids basis. The remainder consists of a very large number of compounds. These are customarily characterized by classes

■ proteins

■ saponins

■ isoflavones ... etc.

Each class may comprise a fairly large number of specific molecules.

Direct recovery of selected individual compounds from such a complex mixture is bound to be difficult. Processes which might be contemplated for effecting the same by the use of generally applicable methods such as HPLC are impractical.

Disclosure of the Invention

According to the present invention there is now proposed and provided an approach for obtaining desired components from soy molasses, which approach is based on primary fractionation in which the feed is split into fractions each consisting mainly of a single class of compounds. Fractions of interest are then subjected to secondary separations by means that could not be practically applied to the original feed.

This process is designed for use with primary fractionation of SM aiming to obtain fractions distinguished by greatly narrowed distribution profiles. In the present process no chemical transformations are involved and the fractions fall into the category of food materials equivalent by definition to SM. Consequently, some of these fractions can conceivably already constitute desirable end products. Others could be convenient starting materials for the recovery of specific compounds by simple and efficient secondary separations.

In order that the process to be defined and exemplified hereinafter will be better understood, background regarding SM characteristics and the theoretical basis upon which the present process is based will now be presented herein. 2

Considering first as an example, soy molasses of 64% solids. 100grs contain 36grs or two mols of H₂O. The remaining 64grs are a mixture of polar compounds. Using carbohydrates as a model for estimating, the average weight per polar group approximates CHOH = 30 or «2 equivalents per 64grs, i.e. there is present about 1 -OH, -CO- and -NH- group for each water molecule. Obviously, at such high concentration levels strong interactions of solute/solute molecules obtain. These will increase with decrease in water content (i.e. with increase in SM solids content) and decrease with dilution by water. Specifically these interactions explain the apparent water solubility of molecules that per se would not be described as such. In fact water solubility is an inaccurate term. Phase homogeneity depends on mutual solubiiization. One can thus safely deduce that in solvent-based separation processes of MS concentration in solvent will be a primary parameter. The alkanols ethanol (EtOH) and 2-propanol (IPA) mixed with water are used as solvents in industrial manufacture of soy concentrate; extracted substances end in SM. The ratio of water/alkanol is determined by two practical requirements:

• preventing the proteins present in the soy flakes from dissolving (and even from excessive swelling);

• maintaining a high solubility of carbohydrates and other non-protein constituents. The former defines a minimum of alkanol content, the latter a maximum. Both can vary in a range determined by operational factors.

Thus, in addition to highly water soluble compounds such as carbohydrates, SM contains compounds that were extracted from defatted soy by virtue of the alkanol content of the extracting aqueous solvent. Such compounds can be present as a stable solution in SM by virtue of the solvation effects. The dependence of SM composition on alkanol content of extracting solvent has now been found, according to the present invention, to tailor a separation process based on aqueous solvents, wherein the ratio of water to the organic solvent component plays a primary role. Thus, according to the present invention it has now been found that fractionation by solvents consisting of water and at least one water soluble organic compound and driven by controlled adjustment of concentration, of solvent composition and of temperatures can be achieved. Continuing, however, first with an explanation of the theoretical basis upon which the process of the present invention is based, there is now presented a model of SM diluted by EtOH and water. One may safely expect that for the water/EtOH ratio and solids level that obtained in the extraction that generated the SM, complete or very nearly complete dissolution will take place. Now, keeping the solids to solvent ratio constant, one can examine the effect of decreasing water/EtOH ratio. At some point one expects phase separation due to carbohydrates (and possibly other compounds) the solubility of which decreases with the decrease of the hydration level of the system. The solubility of sucrose in water/EtOH mixtures which has been studied in detail may be taken as a model and is set forth in the following Table 1.

Table 1 solubility of sucrose in H₂O/EtOH mixtures at 25°C

EtOH wt% Sucrose/1 OOsolvent Sucrose/1 OOwater contained in solvent

0 67.6 67.6

8.62 65.2 71

15.79 62.2 74

24.88 58.1 77

33.53 52.9 80

42.48 46.1 80

51.83 39.6 82

61.3 25.4 66

72.38 11.39 41

86.15 1.675 12

92.5 0.401 5

99.42 0.065 11

One notes the sharp decrease in sucrose solubility at about 70% EtOH. Soy carbohydrates may be expected to have a similar solubility pattern. While in the simple tricomponent system W-sucrose-ethanol phase separation consists of solid sucrose in equilibrium with its saturated solution, in the 4 multicomponent system water-SM-EtOH there may be several solid species precipitating as well as an additional liquid phase formation.

Disregarding the latter possibility, at this point there is presented as a model a solution of SM in W/EtOH that is just saturated and which is then subjected to two procedures whereby precipitation of solids is forced:

• (I) - increments of solvent are removed without change in solvent composition, e.g., by distillation of the solvent with water and readjustment of the water solvent ratio to reestablish the original ratio thereof, after each removal the solids that precipitate are collected;

• (II) - increments of water are removed, e.g., by distillation with an entrainer such benzene, or by use of a molecular sieve, each increment being replaced by an equal weight of EtOH; and after each removal the solids that precipitate are collected;

(I) will emphasize saturation effects at a selected solvent composition; (II) will emphasize sensitivities of solubility to solvent composition. For sufficiently small increments, both procedures impose the expression of selectivities in the solid fractions recovered: (1) along a concentration gradient, (II) along a solvent composition gradient.

Proceeding further, there is presented a model in which EtOH is replaced by a propanol (PrOH) or a butanol (BuOH). A solvent represented by a water/alkanol may be imagined as a homogeneous medium of hydrophilic -OH groups and hydrophobic CH₃, CH₂, and CH groups. Each water molecule and each alkanol molecule contributes one -OH; the (C)s are all contributed by the alkanol. Thus for every water/alkanol solvent one can compute a unique molar ratio R=C/O as

illustrated by Table 2 hereinafter and with reference to appended Fig.1 :

Table 2

Alkanol, wt% R EtOH R PrOH R BuOH

0 0.00 0.00 0.00

10 0.08 0.10 0.11

20 0.18 0.21 0.23

30 0.29 0.34 0.38

40 0.41 0.50 0.56

50 0.56 0.69 0.78

60 0.74 0.93 1.07

70 0.95 1.24 1.45

80 1.22 1.64 1.97

90 1.56 2.19 2.75

100 2.00 3.00 4.00

Both propanols, nPrOH and IPA, are water soluble in all proportions at room temperature; the same obtains for terBuOH; the other three butanols have considerable water miscibility at room temperature and each becomes completely miscible above a critical solution temperature. These alkanois were chosen as convenient illustrative candidates.

Assuming that solvent properties are roughly equivalent at equal R-values, an 80% BuOH or 87% PrOH could replace a 100% EtOH. Higher alkanois thus extend considerably solvent ranges in which selectivities to solutes can be modulated. Obviously this argument applies to other organic compounds that have considerable water miscibility such as ethylacetate, acetone.... Organic/water solvents wherein the organic part consists of two or more compounds makes for further fine modulation of properties.

Solvents of organic component of limited solubility will form a two liquid phase system in contact with SM over a range of solvent to SM ratios and so will solvents of which the organic component is fully miscible, this occurring in zones of high C/O ratios. Water in such system may be regarded as distributing between an aqueous and an organic phase whereby a parameter of control, i.e., hydration level, is established which would be absent or extremely limited in the EtOH-H₂O-SM 6 system, which is the system used industrially to obtain soy molasses and which, in turn, may explain the absence of reported observations potentially leading to the present invention..

Having now presented the theoretical basis upon which the present invention is based, one can appreciate that according to the present invention there is now provided a process for fractionating soy molasses, whereby successive fractions are obtained in which the global C/O ratio of compounds containing only carbon, hydrogen and oxygen atoms, is increased with each successive fraction, said process comprising carrying out a series of successive extractions effected by mixing molasses with a solvent to establish equilibrium, separating the resultant solvent phase from the aqueous phase, mixing a separated aqueous phase from a previous extraction with a further aliquot of solvent to establish equilibrium. separating the resultant solvent phase from the aqueous phase and recovering a product representing a fraction of soy molasses from each successive liquid extract by methods known per se, said solvent being selected from the group consisting of compounds containing only carbon, hydrogen and oxygen atoms, said compounds having a C/O ratio of at least 3 and having up to 6 carbon atoms.

In preferred embodiments of the present said solvent is a C₃ - C_& alcohol.

As will be described hereinafter, in especially preferred embodiments of the present invention the separated aqueous phase is subjected to solid/liquid separation before recombination of the liquid component of the aqueous phase with a further aliquot of solvent.

Preferably, such solids are separated as an additional product of lower C/O than the product contained in the corresponding solvent phase.

In other embodiments of the present invention solids that precipitate to form an aqueous slurry are retained in the slurry and said slurry is subjected as such to the next extraction.

In preferred embodiments of the present invention solvent extracts are subjected to staged dehydration and evaporation operations so as to recover from such extract successively at least two products of increasing C/O ratio.

While the invention will now be described in connection with certain preferred embodiments in the following examples and with reference to the appended figures so that aspects thereof may be more fully understood and appreciated, it is not 7 intended to limit the invention to these particular embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the scope of the invention as defined by the appended claims. Thus, the following examples which include preferred embodiments will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purposes of illustrative discussion of preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of formulation procedures as well as of the principles and conceptual aspects of the invention.

Brief Description of the Drawings

In the drawings:

Fig. 1 is a graphic representation comparing C/O ratios for different alkanol/water systems;

Fig. 2 is a schematic illustration of a general process scheme according to the present invention;

Fig. 3 is a schematic illustration of a specific process scheme according to the present invention;

Fig. 4 is a schematic illustration of a further process scheme according to the present invention; and

Fig. 5 is a schematic illustration of a process scheme for recovery of solutes.

Description of Preferred Embodiments

Examples A series of Soy Molasses fractionation according to the present invention is carried out utilizing ordinary lab glassware for contacting molasses with solvent. The traditional separator/ funnels are generally unsuitable due to molasses viscosity. Round-bottomed flasks provide for convenient mixing by shaking and flat-bottomed beakers which are also convenient for magnetic stirring are used. The low viscosity light solvent phase is easily decanted.

Thermostatic water baths; centrifugues spinnig small and larger tubes, of 10ml and 50ml size are used and the system is set up for rapid instrumental analysis of characterising constituents by HPLC. Compounds (or compound classes) of particular interest may be determined optically by UV or IR absorption. Example 1. 8

Soy molasses of 70% solids was analyzed and the C/O ration was determined to be R=2.68. No correction was made for the content of compound containing nitrogen which assayed about 1 % of solids.

100grs of this molasses was mixed at 52°C with 300grs solvent consisting of 70% nPrOH and 30% water by shaking manually in a round-bottomed flask and the mixture allowed to settle. After 30 min. A nearly clear and fluid solvent phase weighing about 310grs was poured off a viscous aqueous slurry of approximately 90grs. The solvent phase contained ~36grs solids of R=3.49. The aqueous slurry was dried and found to have R=1.13. Example 2.

Using the same molasses, same contacting procedures and same temperature as in Example 1 , 100grs molasses was contacted first with 150grs solvent of 80% nPrOH and 20% water to obtain a first extract of ~165grs and the aqueous phase was directly contacted with 150grs of fresh solvent of the same composition to obtain a second extract weighing ~144grs and a final residue. Amounts of solids (in figures rounded to the nearest gr.) in the three products and their R=C/O values are tabulated below:

Product from 1 st Extract 2nd Extract Aqueous Residue

Amount grs 18 26 26

R=C/0 3.28 3.81 1.1

This example illustrates the process scheme of Figure 3

Example 3.

200grs of a solvent consisting of 160grs nPrOH and 40 grs water were contacted with 100 grs molasses as in Example 1 , to obtain 85grs of a first aqueous product and an extract that was contacted with 100grs if fresh molasses, whereby 240grs of a final extract were recovered and 75grs of a second aqueous product.

Amounts of solids (in figures rounded to the nearest gr.) in the three products and their R-C/O values are tabulated below:

Product from 1st Aqueous 2nd Aqueoust Extract

Amount grs 42 34 64

R=C/6 1.32 1.39 4.15

This example illustrates the scheme presented in Figure 4. 9

Example 4.

Example 1 was repeated to obtain 310grs of solvent extract. This extract was introduced into a simple distillation unit consisting of a flask heated by an electrical mantle joined to a water-cooled condenser and 130grs were distilled off without reflux under atmospheric pressure. The material remaining in the flask was allowed to cool to 50°C and the solvent layer decanted from the thick aqueous paste that formed. The latter was dried to recover ~18grs of solids with an R=1.35, whereas the solvent layer yielded ~28grs of R=4.82.

This example corresponds to Fig. 5.

Said Fig. 5 has many ramifications for the processes of the present invention, as also described below.

Solvent extracts contain solutes that are essentially water soluble e.g. carbohydrates and solutes that are markedly hydrophobic. The former are retained by virtue of the water content of the solvent, the latter by virtue of the organic component that has a ratio of C/O>2.

For convenience of discussion these two groups of compounds are named Group 1 and Group 2 (hereinafter referred to as G1 and G2 respectively).

G1 can be recovered by controlled dehydration since their solubility decreases with the decrease of water content in the solvent. Such dehydration is easily obtainable by azeotropic distillation. Most organic solvent components of C/O>2 form operationally convenient azeotropes which permit lowering of the water content from the initial value to zero without recourse to an additional component acting as entrainer. Thus carbohydrates in an extract can be precipitated by azeotropic dehydration and collected as a single product or a solubility graduated series of products. Naturally, the anhydrous organic phase will be saturated with respect to the compounds that precipitate. The recovery of such residual amounts is obtained by appropriate recycles.

G2 compounds retained in an anhydrous organic phase can be recovered by complete solvent evaporation. However this will recover concurrently residual G1.

To circumvent this contamination and also avoid the danger of thermal damage in complete evaporation, one can evaporate to reach a desired level of G2 10 concentration then precipitate G2 by water - a precipitate that will not carry in it water soluble G1.

Figure 5 schematizes the foregoing.

The solids (and possibly aqueous slurries) formed in the Dehydrating Distillation are collected as a sequence of fractions thus further refining fractionation.

Likewise precipitation of G2 by the addition of water is carried out in successive increments to achieve further fractionation.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative examples and that the present invention may be embodied in other specific forms without departing from the essential attributes thereof, and it is therefore desired that the present embodiments and examples be considered in all respects as illustrative and not restrictive, reference being made to the appended claims, rather than to the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Thus, while the above examples involved the use of nPrOH and short, i.e., few sequential operations, obviously other solvents and additional sequential operations can be used in the present invention and are included within the scope thereof.

Claims

11

WHAT IS CLAIMED IS:

1_. A process for fractionating soy molasses, whereby successive fractions are obtained in which the global C/O ratio of compounds containing only carbon, hydrogen and oxygen atoms, is increased with each successive fraction, said process comprising carrying out a series of successive extractions effected by mixing molasses with a solvent to establish equilibrium, separating the resultant solvent phase from the aqueous phase, mixing a separated aqueous phase from a previous extraction with a further aliquot of solvent to establish equilibrium, separating the resultant solvent phase from the aqueous phase and recovering a product representing a fraction of soy molasses from each successive liquid extract by methods known per se, said solvent being selected from the group consisting of compounds containing only carbon, hydrogen and oxygen atoms, said compounds having a C/O ratio of at least 3 and having up to 6 carbon atoms.

2. A process according to claim 1 , wherein said solvent is a C₃ - C₆ alcohol.

3. A process according to claim 1 , wherein said solvent is a propanol.

4. A process according to claim 1 , wherein said solvent is a butanol.

5. A process according to claim 1 , wherein the separated aqueous phase is subjected to solid/liquid separation before recombination of the liquid component of the aqueous phase with a further aliquot of solvent.

6. A process according to claim 1 , wherein solids are separated as an additional product of lower C/O than the product contained in the corresponding solvent phase.

7. A process according to claim 1 , wherein solids that precipitate to form an aqueous slurry are retained in the slurry and said slurry is subjected as such to the next extraction.

8. A process according to claim 1 , wherein carbohydrates in said separated solvent phase are precipitated by azeotropic dehydration.

9. A process according to claim 1 , wherein water is added to one or more of the successive extractions.

10. A process according to claim 1 , wherein solvent extracts are subjected to staged dehydration and evaporation operations so as to recover from such extract successively at least two products of increasing C/O ratio.