CA1182813A - Process for extracting oleaginous seed material - Google Patents

Abstract

Abstract of the Disclosure There is disclosed a process for extracting particles of oleaginous seed material with aqueous alcohol solutions, wherein displacement of dilute alcohol in the flakes is completed by concentrated alcohol at or near the boiling temperature thereof. In one embodiment of the present invention, the oleaginous seed material is sequentially extracted in five steps, comprising: contact with relatively cool and dilute aqueous alcohol to remove some or all of the alcohol-soluble carbohydrates and non-oil lipids; contact with relatively cool and concentrated alcohol to displace dilute alcohol; contact with concentrated alcohol at or near the boiling point to complete displacement of dilute alcohol and to initiate oil extraction;
contact with undistilled, recycled concentrated alcohol at or near the boiling point to partially remove oil; and contact with distilled concentrated alcohol at or near the boiling point to complete oil removal; followed by desolventizing of the residual solids to yield a protein concentrate or flour.

Description

PROCESS FOR_EXTRACTING_OLEAGINOUS SEED MATERIAL
Field of the Invention This invention relates to the solvent extraction of oleaginous seed materials, and more particularly to a novel process for extracting oleaginous seed materials utilizing aqueous alcohols to produce protein flours or protein concen-trates~
Back~round of the Invention In earlier disclosures, exemplified by U.S. Patents Nos. 4,144,229 and 4,219,470 assiyned to the same assignee as the present invention, I have described the use of aqueous solutions of alcohols, such as ethanol and isopropanol to extract carbohydrates, non-oil lipids and oil in three or four sequential extraction steps.
In U.S. Patent No. 4,219,470 there are disclosed processes for preparing a protein concentrate from oleaginous seed material. In the four step process thereof, the oleagi-nous seed material is sequentially extracted in the steps comprising: contact with a relatively dilute aqueous alcohol to remove carbohydrates and phosphatides; contact with concentrated alcohol to displace dilute alcohol; contact with undistilled, recycled concentrated alcohol at or near the boiling point to partially remove oil; and contact with distilled concentrated alcohol at or near the boiling point to complete oil removal. The novel protein concentrate is obtained by desolventizing the extracted residue.

In U.S. Patent NoO 4,144,229 there are disclosed processes for preparing a novel protein Elour under condi-tions such that, some but not all oE the carbohydrates and non-oil lipids are extracted to produce a proteln flour and, in particular, a soy flour, which is a product of unspeci-fied, but lower protein content than the 70% specified for soy protein concentrate. This soy flour has cer-tain desired characteristics. These characteristics are: a reduced content of the non-oil lipids that give soybean products a beany flavor, a reduced content oE those carbohydrates which cause flatulence, and color which is whiter than that of commercially available soy flours.
In such processes, after extraction in a first step with 50 ~o 70 weight percent alcohol of all or some of the carbohydrates and non-oil lipids from the full fat flakes, the flakes are contacted in a second step with concentrated alcohol to displace the dilute alcohol, consequently making it feasible to extract oil in a third step. The second step is mandatory in such process because even at or near the solution boiling temperature, oll has limited solubility in 92 weight percent aqueous ethanol, the highest concentration, because of azeotrope formation, that can be recovered from ethanol solutions by simple rectification. At ethanol concentrations only slightly lower than 92 percent, the solubility of oil is reduced to an impractical amount. Any dilution of the concentrated alcohol by water entering with the flakes from the second step effectlvely reduces oil solubility.
Similar considerations apply to the other alcohols, i.e., isopropanol, in whose aqueous solutions oil has limited solubility, and which forms an azeotrope with water that limits the practical maximum alcohol concentration.
Oil is extracted in the aforesaid third step with 92 percent alcohol. The oil-rich solution is cooled to precipitate most of the oil, which is removed from the process; and the lean solution, still containing some oil, is recycled to the third step. Extraction of oil from the flakes is completed in a fourth step, where the solvent is distilled 92 percent alcohol.
If the protein product can tolerate some or most of the carbohydrates, the first step may be minimized or elimi-nated, as was disclosed in U.S. Patent No. 4,144,229.
If the water solubility of the protein in the protein product is to be preserved, both such first and second steps should be carried out at the lowest feasible temperature. It is well known that protein denaturation is accelerated, particularly at increased temperature, by contact with aqueous alcohol ranging in concentration from 50 to 70 percent, whereas protein denaturation is little affected by 90 percent alcohol even at its boiling point.
Objects of the Invention An object of the present invention is to provide an improved process for treating oleaginous seed materials using aqueous alcohols as the extraction solvent for the carbohydrates, non-oil lipids and oil.
Another object of the present invention is to provide an improved process for extracting oleaginous seed material with aqueous alcohol solutions to produce a pro-teinaceous flour.
Still another object of the present invention is to provide an improved process or extract.ing full-fat soybean flakes with aqueous alcohol solutions to remove a portion of the carbohydrates and non-oil lipids and substantially all of the oil.
Another object of the present invention is to provide an improved process for extracting full-fat soybean flakes with aqueous alcohol to remove substantially all of the alcohol soluble carbohydrates and non-oil lipids and substantially all of the oil to produce soy protein con-centrate.
Another object of the present invention is to provide an improved process, with reduced utility costs, for extracting full-fat soybean flakes with aqueous alcohol to remove substantially all of the carbohydrates and non-oil lipids and substantially all of the oil to produce soy protein concentrate.
A still further object of the present invention is to provide an improved process, requiring shorter processing time, for extracting full-fat soybean flakes with aqueous alcohols to remove substantially all oE the alcohol soluble carbohydrates and non-oil lipids and substantially all of the oil to produce soy protein concentrate.
$till another object oE the present invention is to provide an improved process for extracting Eull fat soybean flakes with aqueous alcohol solutions using percola-tion extraction techniques.
Another object of the present invention is to provide an improved process requiring shorter processing time for preparing a novel protein flour by extracting particulate oleaginous seed materials using aqueous alcohol solutions as extraction solvents.
Summary of the Invention -These and other objects of the present invention are achieved by extracting particles of oleaginous seed material with aqueous alcohol solutions, wherein displacement of dilute alcohol in the flakes i5 completed by concentrated alcohol at or near the boilin~ temperature thereof.

In one embodiment of the present invention, the oleaginous seed material is sequentially extracted in Eive steps, comprising: contact with relatively cool and dilute aqueous alcohol to remove some or all of the alcohol soluble carbohydrates and non-oil lipids; contact with relatively cool and concentrated alcohol to displace dilute alcohol;
contact with concentrated alcohol at or near the boiling point to complete displacement of dilute alcohol and to initiate oil extraction; contact with undistilled, recycled concentrated alcohol at or near the boiling polnt t~ par-tially remove oil; and eontact with distilled concentrated alcohol at or near the boiling point to complete oil removal;
followed by desolventizing of the residual solids to yield a protein concentrate or flour.
Brief Description of the Invention A better understanding of ~he present invention as well as additional objects and advantages ~hereof will become apparent upon consideration of the detailed disclosure thereof when taken with the accompanying drawing which repre-sents a schematic flow diagram of the present invention.
Detailed Descrlption of the Invention Although the process is hereinafter more fully described as applied to soybeans to produce a soy protein flour, it is to be understood that it is equally applicable to other oilseeds, such as cottonseeds, peanuts, sesame seeds, sunflower seeds, i.e.~ seeds containing high concen-trations of nutritious proteins.
Soybean flakes are prepared by first cracking clean soybeans between corrugated rolls into 4 to 8 pieces which are then Aehulled, softened by heat at about 160F~ and flaked between smooth rolls. Soybean flakes are typically about 0.5 inch in diameter and 0.010 inch thick. Other oil !. 3 seeds may be similary flaked or simply ground to a maximum particle size of about 0.25 inch. Such flakes as now pre-pared for hexane extraction are equally well suited for the process herein disclosed.
Referring now to the drawing, particulate oleagi-nous seed materials in line 1 are sequentially passed through Steps I to V. Hot distilled aqueous alcohol, at least 92 weight percent ethanol at or near its boiling point, is introduced through line 2 into Step V and contacts flakes from Step IV. Carbohydrates and non-oil lipids have been extracted from these flakes in Steps I and II, and most of the oil extracted in Step IV. Extraction of oil is completed in Step V. Deoiled flakes exit Step V in line 3. Miscella from Step V is introduced into Step IV through line 4 at a point downstream of a heated recycled alcohol stream in line 5. Miscella is withdrawn from Step IV by line 6 and intro-duced into Step III, as more fully hereinafter discussed.
The remaining miscella from Step IV i5 withdrawn by line 7 and cooled in heat exchanger 8 to precipitate an oil phase.
Mixed phases in line 9 are separated in a decanter or centri-fuge 10 from which are withdrawn an alcohol phase in line 11 and heavier oil phase in line 12. The alcohol phase in line 11 heated in heater 13 constitutes the heated recycled alcohol introduced into Step IV by line 5.
While the alcohol soluble non-oil lipids appear to be completely extracted in Steps I and II r it may be found in commercial practice that some non~oil lipids may accumulate in the recycled stream, since such non-oil lipids are very soluble in 90% alcohol at 100F. In that event, a small purge stream 14 is drawn off and passed to any suitable process, such as evaporation, by which means the alcohol could be recovered for recycle to the process.
A portion of the miscella rom Step IV in line 6 in used in Step III to complete dehydration of and to initiate oil extraction from the flakes. The miscella withdrawn from 1U Step III in line 15 is cooled, preferably to the temperature used in Step I and II, in a heat exchanger 16 to precipitate an oil phase. Mixed phases in line 17 are separated in a decanter or centrifuge 18, from which the alcohol phase exits in line 19 and the heavier oil phase exits in line 20. This oil may be combined with the oil in line 12 for further processing (not shown).
The alcohol phase in line 19 flows to Step II.
Miscella exiting ';tep II in line 21 is admixed with water in line 22 and introduced by line 23 into Step I downstream of the point of introduction of the dilute alcohol stream in line 24. The amount of water added in line 22 is that required to dilute the alcohol in stream 21 to the same concentration as the alcohol in stream 24, which for aqueous ethanol may be any concentration between 50 and 70 percent at the option of the plant operator. Final miscella containing carbohydrates and non-oil lipids in solution exits the process in line 25.
Substantially all of the carbohydrates and non-oil lipids soluble in aqueous alcohol dissolve in Steps I and II. Oil which enters Step II in the liquid stream is almost completely precipitated as the alcohol is diluted in Steps II
and I. Precipitated oil deposited on the flakes is recycled to Step III and redissolved. Carbohydrate miscella exiting in line 25 may be practically free of undissolved oil. Oil exiting in lines 12 and 20, having been precipitated from a solution containing little carbohydrate and non-oil lipids, is pale yellow and free of "break".
As applied to soybeans, in Step I carbohydrates and non-oil lipids are extracted from the full-fat flakes at temperat~res preferably in the range of 95 to 175F., using as the solvent in line 24 aqueous ethanol in the con~entra-tion range of 50 to 70 weight percent. It has been found that the extraction of carbohydrates and phosphatides in Step I is not, and need not be, complete. Even in alcohol concen-~0 trations as high as 70 percent, the flakes imbibe solvent and become swollen. Consequently, extractionof the last of the carbohydrates by diffusion into the alcohol solution that surrounds the flakes is slow. Fortunately, the flakes shrink considerably as they move through Steps II and III, thus being in effect pressed. Dissolved carbohydrates in the flakes leaving Step I are thus largely removed in Steps II

and III, even th~ugh the concentrated alcohol used in those steps is not a good solvent for carbohydrates. Since the solution in line 21 contains carbohydrates and non-oil lipids, it is introduced, after dilution with water, into Step I at a point downstream from the entry of distilled solvent in line 24, optimally at the point where the miscella flowing through Step I from the right has the same solute concentration as that in stream 23.
In Step II, the flakes are dewatered, preferably at ~he same temperature as in Step I, by countercurrent extrac-tion with aqueous concentrated alcohol from Step III, generally, approximately 90 weight percent ethanol. Extrac-tion temperature and alcohol concentration in Steps I and II
depend on the properties desired in the protein product.
High temperature and low alcohol concentration cause rapid loss of protein dispersibility and water absorption, which it is often desired to preserve. As taught in the hereinabove mentioned U.S. Pat~ent No. 4,219,470, a soy protein concen-trate with a high protein dispersibility index (PDI) can be obtained by prolonged extraction with 70 percent ethanol at 95~F. If PDI is o~ no concern, extraction can be accelerated and a lower ratio of solvent to flakes employed by extracting with ethanol as dilute as 50 percent and at a temperature as high as the boiling point.
I have found that complete displacement of dilute alcohol by concentrated at low temperature in Step II, as taught in my previous c1isclosures, is not necessary. Partlal displacement at low temperature in Step II followed by completion of the displacement at high temperature in Step III is attended by little loss of protein dispersibility.
Complete dehydration of the flakes is effected in Step III at the same temperature as that of Steps IV and V, preferably at or near the boiling point of the concentrated alcohol. The saving in cost of extractors is considerable, since complete displacement of dilute alcohol is much more rapid at the higher temperature.
In Steps IV and V oil is extracted by concentrated alcohol, e.g. ethanol solution of at least 92 weight percent alcohol, at or near the boiling temperature. Soybean oil has a solubility of only about 3O5 percent in boiling 90 weight percent ethanol, and since a practical maximum concentration in line 2 of ethanol recovered by distillation is 92 percent r it becomes apparent why Steps II and III are required to effect almost complete displacement of dilute alcohol. Oil is removed from the process by virtue of the difference in its solubility at the boiling temperature and at the tempera-ture in line 9, which without resort to refrigeration is at least 100F. With 90 percent ethanol, this difference is about 2.25 percent. While practical considerations limit the concentration of aqueous ethanol that can be recovered by simple rectification to 92 percent, stronger concentrations can be realized by well known methods. The use of ethanol solutions oE up to 100 weight percent ethanol is contem-plated in the process of the present invention.
It is desirable to produce in Step IV an oil solution as nearly saturated as possible. Consequently, an oil concentration gradient must be developed in the alcohol solution as the alcohol solution moves from right to left so that the alcohol solution first contacting the flakes entering Step IV is nearly saturated. I have observed that the very first oil is rapidly extracted from the flakes, after which the rate is reduced. However, the oil solution flowing from Step IV to Step III in line 6 need not be fully saturated since the oil solution becomes saturated in Step III. That is why miscella in line 6 is removed from Step IV
before the end of the liquid path.
Even though the flakes are last contacted in Step IV by a recycled solution in line 5 containing about 1 percent of oil in aqueous alcohol having a concentration as high as 91 percent, there is a notable increase in the rate of oil extraction when the flakes are contacted with only ~0 slightly stronger alcohol in Step V. Consequently, the concentration of oil in the miscella leaving Step V in line 4 may well be over 1 percent. Thus, miscella in line 4 from Step V is best introduced into Step IV at a point downstream of the point of introduction of the recycled solution in line 5, and preferably at the point where the oil concentration in the solution flowing through Step IV matches that in stream 4.

There has been dlsclosed and used a great variety of equipment and methods for extracting particulate oleagi-nous seed materials. In less preEerred methods, particulates are immersed in and conveyed through the solvent, either in countercurL-ent stages, each consisting oE a soaker followed by solids-liquid separation, or ln a column or conveyor in which there is counterflow of particulates and solvent.
When the particulates are flakes, there is considerable breakage and fines in the miscella which are troublesome. It has been the experience in the extraction of oilseeds that percolation extraction, defined as a process in which the particulates form beds through which solvent percolates, is superior to immersion extraction. The reasons are that the bed itself is an excellent filter for the miscella, that the spent particulates can be drained by gravity prior to desol-ventizing, that the bed affords efficient contact between particulates and solvent, and that there is practically no mechanical wear of the equipment.
Although the process of my invention may be practiced in any suitable countercurrently operated liquid-solids contractors used for washing or leaching, I prefer, based on the experience of the oilseed industry, to employ percolation extraction techniques. A commercially proven extractor, particulatly suited for the practice of my inven-tion, is the rotary extractor described in U.S. Patent No.

2,840,459.

In that extractor, a rotor divided into sector cells rotates in a vapor-tight tank above stationary stage compartments. Each cell is open at the top and closed at the bottom by a hinged perEorated door. Solids are fed con-tinuously into each cell as it passes under a loading zone, and fall from the cell when its door opens above a discharge zone almost completely around the circle from the feed zone~ Solvent is advanced counter to the direction of rotation by a series of stage pumps, which pump miscellas of graduallly increasing concentration into distribution mani-folds positioned over the free-draining beds formed in the cells.
Extraction of 1akes in a percolation extractor can be faithfully simulated in the laboratory by percolating through a bed of flakes in a stationary vertical tube a succession of miscellas of decreasing concentration, corre-sponding to the miscellas collected in the stage compartments and pumped to the manifolds by each stage pump. To establish correct concentrati~ns of the miscellas, a first batch of flakes is extracted with fresh solvent only, and the miscella draining from the bed is collected in successive measured cuts. The first cut, equivalent to final miscella, is discarded, and other cuts are percolated in succession through a second batch of flakes, followed by an amount of fresh solvent whose ratio to flakes in the batch is the same as the ratio of solvent to ~lakes fed in the continuous process being simulated. After treating several batches of flakes, the concentration of the miscella cuts reach a steady state characterlstic of the operation of a continuous extractor.
Simulation of the complete process of the present invention -by extraction of successive batches is more com-plexO Nevertheless the five-step process can be simulated by accumulating five sets of miscella cuts, advancing miscella from Step V to IV to III to II to I, and carrying out the cooling, mixing, recycling, and reheating as shown in the drawing.
The parameters that determine the steady state in any one step of extraction are temperature, ratio of solvent to feed, and time. Simulation of the five-step process of the present invention is more complex in that additional parameters must be selected, e.g. alcohol concentration and flow rate in lines 2 and 24, recycle solution flow in line 5, temperature of two-phase flow in line 9 and temperature and retention time in each of the five steps~
E~
Full-fat dehulled soybean flakes were extracted in accordance with the process of the present inventionO In a number of successive batches, flakes were presoaked in the solution equivalent to that in line 25 (Figure 1) for 10 minutes and then poured into a vertical glass tube closed at the bottom by a screen. Each batch was treated in immediate succession with aqueous ethanol solutions as in Figure 1.
Retention times in Steps I and IV were 60 minutes; in Steps II, III and V, 30 minutes each. Temperature in Steps I and II was 130F.; in Steps III, IV and V, 175F. (boiling point). The runs were based on the following additional parameters as set forth in the following Table I, using as a basis 100 pounds of ~lakes in line 1.
Table I
Lines 2 11 19 24 Temperature F. 175 110 130134 Flow (pounds ) 135 775 - 86 ETOH Conc. (wt.%) 92 - ~ 60%
When the steady states was reached, the various streams were measured as set forth in the following Table II:
Table II
Lines 3 7 1222 25 Flow (pounds)104 793 19.7 27 220 Solute (wt.%) - - - 0 8.5 Lipids (wt.%)0.9* 3.6 91 0 Neg.
ETOH Conc. (wt.%) - 91 - 0 62 Volatiles Iwt.%) 50 - 9 Protein (wt~)71.2* - - - 0.11.
* dr~ basis The soy protein concentrate made in this Example 13 at least as good as the concentrate produced in the experi-mental work described in U.S. Patent No. 4,219,470. The concentrate was tasteless, and met or exceeded all oE the 5criteria now expected of commercial soy protein concentrate.
Comparison of the data in Tables I and II with the corresponding data for the production of soy protein concen-trate given in Table I of U.S. Patent No. 4,~19,470, clearly showns that the innova~ions described in the present disclo-10sure have improved the process. In UOS. Patent No. 4,219,470 the total retention time was four hours; it is now reduced to three and a half hours. Probably even more important, the flow in line 2, which was 170 pounds, is now reduced to 135 pounds. The flow in line 14 of the patent, which corresponds 15to the sum of the flows in lines 21 and 24 of the present disclosure, was 230 pounds compared with the present sum of 157 pounds. Anoth~er easily understood improvement is that the flow in line 15 of the patent, which corresponds to line 25 of the present disclosure, was 370 pounds compared ith 220 20pounds.
The reduction in aqueous alcohol flow results from addition of the new Step III and the other innovations, which are: (1) introducing miscella in line 4 at a point in Step IV
downstream from the point of introduction of miscella in line 255; (2) removing the net miscella advanced from Step IV to Step III in line 6 at a point upstream Erom the end of the .~ d ~

flow path in Step IV; (3) diluting the miscella in line 21 with water so that their mixture in line 23 has the same concentration as the dilute distilled alcohol in line 24; and (4) introducing stream 23 at a point in Step I downstream from the point of introduction of stream 24.
This data can be the basis for a commercial process, which includes in its entirety: distilling solvent from the oil phases in line 12 and 20; desolventizing extracted flakes in line 3 -to produce a novel protein concentrate; separating phosphatides (if desired) from the carbohydrate-rich miscella in line 25; and distilling the miscella in line 25 to recover as distillates the strong alcohol required in line 2 and the dilute alcohol required in line 24, and to recover the carbohydrate as bottoms. Such distillation of carbohydrate solutions may be best performed in accordance with the teaching of U.S. Patent No. 3,993~535, assigned to the same assignee as the present invention.
Although the invention is exemplified using soy-beans and ethanol as the alcohol, other monohydric alcohols, such as methanol, and particularly isopropanol, may be used as aqueous solvents. The process can be applied equally well to other oilseeds, such as cottonseed, peanuts and rape seed.

l8

Claims (27)

What is Claimed

1. An improved process for extracting oleaginous seed material comprised of carbohydrates, non-oil lipids and oil to prepare a proteinaceous product therefrom wherein full fat flakes of such oleaginous seed material are sequentially contacted with aqueous alcohol solutions to extract said carbohydrates, non-oil lipids and oil, and wherein a first solution of a dilute alcohol at a low temperature initially extracts some carbohydrates and non-oil lipids from the full-fat flakes and wherein a subsequent concentrated solu-tion of an alcohol at an elevated temperature extracts said oil from the flakes from the initial extraction, the improve-ment comprising: contacting said flakes from said initial extraction with a concentrated solution of an alcohol at said elevated temperature to displace dilute alcohol from said flakes prior to extraction of said oils.

2. The process as defined in Claim 1 wherein said elevated temperature is at or near the boiling point of said concen-trate solution of said alcohol.

3. The process as defined in Claim 1 wherein said subsequent concentrated solution and said concentrated solution of said alcohol are of substantially like alcohol concentrations.

4. The process as defined in Claim 1 wherein said alcohol is selected from the group consisting of monohydric aliphatic alcohols having from 1 to 4 carbon atoms.

5. The process as defined in Claim 4 wherein said alcohol is ethanol.

6. The process as defined in Claim 5 wherein said dilute alcohol has a concentration of 50 to 70 weight percent alcohol.

7. The process as defined in Claim 5 wherein said oleaginous material is soybeans.

8. The process as defined in Claim 5 wherein said concen-trated solution of alcohol contain at least 92 weight percent ethanol.

9. The process as defined in Claim 1 wherein a concentrated solution including extracted oil is cooled to form an oil phase and a concentrated alcohol phase and wherein said oil phase is separated from said alcohol phase, said alcohol phase being the source of a portion of said concentrated solution of alcohol and wherein a concentrated solution of alcohol including extracted oil constitutes said concentrated solution of alcohol at said elevated temperature to displace dilute alcohol.

10. The process as defined in Claim 9 wherein said concen-trated solution of alcohol after displacement of said dilute alcohol is admixed with water to form a portion of said first alcohol solution.

11. The process as defined in Claim 10 where said portion of said first alcohol stream contacts said full fatted flakes prior to said remaining portion of said first alcohol stream.

12. The process as defined in Claim 9 wherein said oleagin-ous material is soybeans and said subsequent concentrated solution is a solution of ethanol in water containing at least 92 percent by weight ethanol.

13. An improved process for extracting oleaginous seed material comprised of carbohydrates, non-oil lipids and oils to prepare a proteinaceous product which comprises:
(a) particulating said oleaginous seed material to form flakes thereof;
(b) contacting said particulate flakes with a dilute solution of alcohol at or a relatively low temperature to extract some of said carbohydrates and said non-oil lipids;
(c) separating a miscella from the flakes of step (b);
(d) contacting said flakes of step (b) at a relatively low temperature with a concentrated solution of alcohol to displace dilute alcohol from said particulate flakes.
(e) separating a miscella from the flakes of step (d);
(f) contacting said particulate flakes of step (e) with a concentrated solution of alcohol at an elevated temperature to further displace dilute alcohol from said particulate flakes;
(g) separating a miscella from the particulate flakes of step (f);
(h) contacting said particulate flakes of step (g) with a concentrated solution of alcohol at an elevated temperature to extract substantially all of said oils;
(i) separating a an oil-rich miscella from the parti-culate flakes of step (h);
(j) cooling said oil-rich miscella of step (i) to separate a solvent phase and a oil phase;
(k) returning said solvent phase to said process;
(l) withdrawing said oil phase from the process; and (m) desolventizing the particulate flakes from step (i) to yield substantially oil-free protein flour.

14. The process as defined in Claim 13 wherein said elevated temperature of steps (f) and (h) are at or near the boiling point of said concentrated solution.

15. The process as defined in Claim 14 wherein said alcohol is selected from the group consisting of monohydric aliphatic alcohols having from 1 to 4 carbon atoms.

16. The process as defined in Claim 13 wherein said miscella of step (d) is admixed with water to constitute a portion of said dilute solution of alcohol of step (b).

17. The process as defined in Claim 16 wherein said miscella admixed with water contacts said full fatted flakes prior to said remaining portion of said dilute solution of alcohol.

18. The process as defined in Claims 13, 16, 17 wherein said miscella of step (g) is cooled to form a solvent phase and a lipid phase.

19. The process as defined in Claim 13 wherein said miscella of step (g) is cooled to form a lipid phase and a solvent phase, said solvent phase constituting said concentrated alcohol stream of step (d).

20. The process as defined in Claim 19 where a concentrated solution of alcohol including oil is withdrawn from step (h) and constitutes said concentrated solution of alcohol of step (f).

21. The process as defined in Claim 20 wherein said concen-trated solution of alcohol of step (h) is comprised of said solvent phase of step (k) after reheat and a distilled concentrated solution of alcohol.

22. The process as defined in Claim 21 wherein said contact of step (h) is first effected with said distilled concen-trated solution of alcohol and subsequently with said sol-vent phase of step (k).

23. The process as defined in Claim 21 wherein said distil-led concentrated solution of alcohol is distilled from the miscella separated from said flakes in step (c) and from flakes desolventized in step (m).

24. The process as defined in Claim 15 wherein said alipha-tic alcohol is ethanol.

25. The process as defined in Claim 24 wherein a remaining portion of said dilute solution of alcohol of step (b) is a solution of ethanol containing of from 50 to 70 weight percent alcohol.

26. The process as defined in Claim 25 wherein said oleagin-ous material is soybeans and said concentrated solution of step (h) is a solution of ethanol in water containing at least 92 weight percent ethanol.

27. The process as defined in Claim 26 wherein steps (a) through (f) are effected at a temperature of from 95 to 150°F.