SE437461B - SET TO MAKE A PROTEIN MILL BY MEDIUM ALCOHOL EXTRACTION - Google Patents

Description

RO 7713304-9 distilled, concentrated alcohol at or near the boiling point to complete oil removal. A new product with a high protein content is obtained by removing the solvent from the extraction residue.

The stated application was aimed at the production of soy protein concentrate, especially for human consumption, whereby the product according to commercial definition contains at least 70% protein. It has now been shown that soy flour, which is a product with an unspecified but lower protein content, will constitute a significant, commercial product, provided that it has certain desirable properties. These properties are that the product is free of non-oily lipids that give soybean products a bean-like taste, that the product is free of such carbohydrates that cause stress, and that the product is as white as possible. The present invention now relates to a process substantially similar to that already described in the previous application, and further to a new process for producing such a new protein flour.

The objects of the present invention are achieved by extracting particulate, oily seed material with aqueous alcoholic solutions.

In one embodiment of the present invention for preparing a novel protein flour, the particulate oily material is extracted successively in two steps, which comprises contacting initially concentrated alcohol to remove water, most of the non-oily lipids and a part of the oil, and contact with concentrated alcohol at or near the boiling point to remove the remainder of the oil.

In a second embodiment of the present invention for the preparation of a novel protein flour, the particulate oily seed material is extracted successively in three steps, which comprises contact with initially concentrated alcohol to remove water, non-oily lipids, some of the carbohydrates and a portion of the oil, contact with concentrated, undistilled and recycled alcohol at or near the boiling point to partially remove oil, and contact with the concentrated alcohol at or near the boiling point to complete the removal, after which the solvent is removed from the solid residue.

In a third embodiment of the invention for the production of a new protein flour, the oily seed material is extracted successively in four steps, which comprise contact with a relatively small amount of pt * * ïf; _f **> '_, ß „gg§Y Dilute aqueous alcohol to remove some of the carbohydrates and non-oily lipids, contact with relatively concentrated alcohol to remove water, contact with undistilled, recycled concentrated alcohol at or below near the boiling point for partial rice removal of oil, and contact with distilled, concentrated alcohol at or near the boiling point to complete the removal of the oil A new protein flour is obtained by removing solvent from the extracted residue.

The invention and its further objects and advantages are further illustrated by the following description taken in conjunction with the accompanying drawing, which shows embodiments of the invention.

In the drawing, Fig. 1 is a schematic flow diagram of the four-step embodiment, and Fig. 2 is a schematic flow diagram of the three-step embodiment.

Although the process is described in detail applied to soybeans, it should be noted that it is equally applicable to other varieties of oilseeds, such as cotton seeds, peanuts, sesame seeds and sunflower seeds, all seeds which have a high content of nutritious proteins.

Soybean flakes are produced by first crushing pure beans between corrugated rolls into 4-8 pieces, which are then peeled, softened by heat at about 70 ° C and formed into flakes between smooth rolls. Soy flakes typically have a diameter of about 12 mm and a thickness of about 0.25 mm. Other oilseeds can be formed into flakes in a similar manner or simply ground to a maximum particle size of about 6 mm. Flakes currently prepared for hexane extraction are equally suitable for the process described herein.

In one embodiment, the process comprises four successive steps, which are schematically shown in Fig. 1. Particulate, oily seed material which is introduced to the left in line 1 is passed successively through steps I, II, III and IV. Hot, aqueous alcohol, typically 92% by weight ethanol at its boiling point, begins at stage IV in line 2 and flows countercurrent to the flakes, which emerge from the process in line 3. Extract solution (miscella) flowing from stage III in line H is cooled in a heat exchanger 5 to precipitate an oil phase. The mixed phases in line 6 are separated in a decanter or centrifuge 7, from which the alcohol phase flows out in line 8 and the heavier oil phase starts from the process in line 9. The alcohol phase is divided, and a regulated proportion flows to a heater ll through the line 12, while re- ...-..-._-.-. ~ .. ~ ........ _ .. -. ... w ........., ........_._ ~.-._ .. ._. _ PÜGI. 10 15 20 25 30 55 H0 7713304-9 the column is introduced into a heater 16 through line 10. Heated solution is returned to step III through line 13, and heated solution flows to step II through line 17. Solvent starting from step II is mixed with dilute ethanol entering line II to form the dilute solution desired in step I. A final extract solution containing carbohydrates and non-oily lipids in solution starts from the process in line 15.

It has been found that substantially all of the alcohol-soluble carbohydrates and non-oily lipids are dissolved in steps I and II. Oil entering stage II of the liquid stream in line 17 precipitates almost completely when the alcohol is diluted in stages II and I.

Precipitated oil deposited on the flakes is returned to step III and redissolved. The carbohydrate solution flowing out of line 15 may be substantially free of undissolved oil. Oil which flows out in line 9 and which has precipitated from a solution containing low carbohydrates and non-oily lipids is pale yellow and free of finely divided material. Although experiments to date have shown that alcohol-soluble, non-oily lipids are completely extracted in steps I and II, in commercial application it may occur "that some of the non-oily lipids may accumulate in the recycled stream 8, since such non-oily lipids are highly soluble in 90% alcohol at HOQC, in which case a small purge stream 18 is drawn off and led to some suitable process, such as evaporation, by which the alcohol can be recovered to be returned to the process. soybeans are extracted in step I some of the carbohydrates and non-oily lipids from the full fat flakes at temperatures suitably in the range of from 35 to 80 ° C, using as the solvent of aqueous ethanol in the content range of 50 to 59 and up to In step II, the flakes are dewatered, preferably at the same temperature as in step I, by countercurrent extraction with ethanol having a content of about 90% by weight. eg III, most of the oil is extracted into a recycled stream of ethanol with a content of about 90% by weight and at or near the boiling point. In step IV, the remainder of the oil is extracted with ethanol having a content of about 92% by weight.

The extraction temperature and alcohol content in steps I and II depend on the desired properties of the protein product. High temperature and low content result in a rapid decrease in the dispersibility and water absorption of the protein, which are sometimes desirable: coon dumt-i; 10 15 20 25 30 35 UO 7713304-9 to maintain. It has been found that soy protein concentrate with a high protein dispersibility index (PDI) can be obtained by prolonged extraction with 70% ethanol at 35 ° C. If PDI is of no importance, the extraction can be accelerated and a lower ratio of solvent to flakes can be used by extraction with as dilute ethanol as 50% and at a temperature as high as the boiling point.

In stage II, diluted alcohol entrained with the flakes from stage I is displaced by concentrated alcohol. The flakes must be in effective contact for a period of time sufficient for complete displacement. For practical reasons, it is appropriate that the temperature in step II be the same as in step I. This is especially true when a high PDI of the protein concentrate product is desired, as the protein will be rapidly denatured if the flakes are in contact with fully diluted alcohol before this. displaced by concentrated alcohol.

When steps I and II are carried out at a temperature at or near the boiling point of the solvent, some oil is extracted in step II, but oil precipitates for the most part from the dilute solution in step I and is re-deposited on the flakes.

In steps III and IV, the oil is extracted with concentrated alcohol at or near the boiling temperature. Since soybean oil has a solubility of only about 3.5% in boiling ethanol with a content of 90% by weight, and the maximum practical content of the ethanol recovered by distillation in line 2 is about 92%, it is clear why step III is usually required and why an almost complete displacement of diluted alcohol in stage II is essential. Oil is removed from the system due to the difference in its solubility at boiling temperature and at the temperature in line 6, which without resorting to cooling is at least 3800. With 90% ethanol, this difference is about 2.25%. Thus, if 8.2 kg of oil is to be extracted from N5, H kg of flakes with full fat content, the flow in the line must be equal to at least 363 kg (18 / 0.0225). If the alcohol content in line H, which is determined by the amount of water entering with the flakes from stage II, falls well below 90%, the flow in line H will be impermissibly high.

In general, it is convenient to cool the extract solution in line U to the minimum that is practical with the available cooling water to minimize the return in step III and improve the extraction in step IV. It should be noted, however, that the heater 16 may be switched off by regulating the temperature in the line 6 pink-QUALITY, 10 20 25 30 55 NO 77133 04-9 to the temperature desired in step II. It will also be appreciated that if the solubility of the oil at the boiling point of the solvent is high, step III can be omitted, i.e. lines 12 and 13 and the heater 11. It is also apparent that it is desirable to have a minimum of solvent carried with the solvents leaving each step. .

The process described above differs from the process described in Swedish patent application 7609766-6 only in terms of the amount of flow in the stream 15. For the production of soy protein concentrate, the flow in the stream must be at least about 2.5 kg per kg of soybeans initiated in line 1. With lower flows, the proteinaceous product contains less than 70_% protein, and is counted as a soy flour.

In the second embodiment of the process, which can be applied if a presence of some or most of the carbohydrates of the beans in the proteinaceous product can be tolerated, step I is omitted and the particulate oily seed materials in line 21 are passed successively through step II. III and IV, as shown in Fig. 2. Hot, aqueous alcohol, typically 92% by weight ethanol and at the boiling point, is initiated in step IV of line 22 and countercurrent to the flakes. Extract solution or miscella starting from stage III in line Zë is cooled in a heat exchanger 25 to precipitate an oil phase. The mixed phases in line 26 are separated in a decanter or centrifuge 27, from which the alcohol phase starts in line 28 and the heavier oil phase starts from the process in line 29.

The alcohol phase is divided, and a controlled portion flows to a heater 31 through line 32, while the remainder is introduced into a heater 36 through line 30. The heated solution is returned to stage III through line 33, and heated solution is passed to stage II through line 37 Extract solution containing small carbohydrates, some oil and most of the alcohol-soluble, non-oily lipids is from step II of line 35.

In carrying out this embodiment of the process, the intention is that the alcohol solution initiated in the line 22 is minimal, for example not exceeding 1.5 kg per kg of flakes introduced into the line 21. At such a low solvent ratio, water which enters with the flakes will dilute the alcohol in step II so that at least some of the carbohydrates will be dissolved. Since non-oily lipids may not be completely extracted in step II, an inappropriate accumulation of non-oily lipids in stream 28 would likely occur during prolonged continuous operation.

W. _ I g fi åí]? C> {) §š | <2i§§ ¥ iñÄL 10 l5 50 H0 7713364-9 It may be necessary to average a song pure current 36 from the 5 'line 28 and direct this current to a stripper, from which condensed aqueous alcohol would be returned to the process, or lead such a stream to any other process that could cause separation between the accumulated contaminants and the aqueous alcohol.

The third embodiment of the process can be applied if anhydrous or almost anhydrous alcohol is available for extraction. In this case, the solubility of soybean oil is high enough that it will not be necessary to include the returned stream in stage III, so that in practice steps III and ïï are combined. According to lig. 2, the process is run in the same manner as indicated for the second embodiment, however, the flow in the line 33 is zero, and no heater 31 is present. Some of the oil is withdrawn in line 29, and the remainder in line 35 together with non-oily lipids, little or none of the carbohydrates are extracted.

A wide variety of equipment and methods have been described and used for the extraction of particulate, oily seed materials.

In less preferred methods, the particles are immersed in and passed through the solvent, either in countercurrent steps, each of which consists of an impregnator, followed by a separation between solid and liquid; or in a column or conveyor in which there is a countercurrent between particles and solvent. When the particles are made of flakes, a considerable amount of decomposed and fine material is obtained in the extract solution, which is inappropriate. It has been found in the extraction of oilseeds that extraction by percolation, defined as a process in which the particles form beds, through which the solvent flows, is superior to extraction by immersion.

The reason is that the bed itself is an excellent filter for the extract solution, that the extracted particles can drip by gravity before the removal of the solvent, that the bed provides an effective contact between particles and solvent, and that practically no mechanical wear of the equipment is present. .

Although the process according to the invention can be carried out in any suitable countercurrent application for contact between liquid and solid material used for washing or leaching, on the basis of experience in the oil industry it is most suitable to use extraction processes by means of percolation. A commercially proven extractor which is particularly suitable for carrying out the invention is Poor. Quinn? 77 1530 50 35 Ä0 7713304-9 the rotary extractor described in U.S. Pat. No. 2,8H0H59.

In this extractor, a rotor which is divided into sector cells in a vapor-tight tank rotates above stationary step spaces. Each cell is open at the top and closed at the bottom by means of a hinged, perforated door. Solid material is introduced continuously into each cell as it passes under a filling zone, and falls from the cell when its hatch opens above a discharge zone, located almost completely around the circle from the supply zone. Solvents are supplied against the direction of rotation by means of a series of step pumps, which pump extract solutions of successively increasing concentration into manifolds, applied over the free-flowing beds formed in the cells.

When performing extraction with percolation, the flakes are usually slurried in extract solution before being introduced into the extractor to form the free-flowing bed. The bed thus formed is homogeneous and free of air pockets. It has been found that flakes to be extracted with an aqueous alcohol must be slurried in recycled extract solution and soaked for 5-10 minutes to ensure that they completely swell. Soybean flakes swell considerably when soaked in diluted alcohol. Flakes with a complete fat content that are sufficient to give a bed with a volume of 1 ms form, after soaking in ethanol with a content of 55% by weight, a bed whose volume is 1.1 m3. If this swelling occurs on site after the bed is formed, the bed becomes impermeable to the flow of solvent.

Extraction of flakes in a percolation extractor can be accurately imitated in the laboratory by percolating through a bed of flakes in a stationary, vertical tube a series of extract solutions with decreasing content, corresponding to the extract solutions collected in the step spaces and pumped to initial tubes. - clean by means of each step pump. To determine the correct levels of the extract solutions, a first batch of flakes is extracted with fresh solvent only, and an extract solution removed from the beds is collected in successive, measured fractions. The first fraction, which is equivalent to the final extract solution, is discarded, and other fractions are successively percolated through a second batch of flakes, accompanied by an amount of fresh solvent, the ratio of the flakes in the batch being the same as the ratio. the process between solvents and flakes which is applied in the continuous process which is simulated. After treatment of a plurality of batches of flakes, the process is simulated....................... the content in the fractions of extract solution is a stationary condition, which is characteristic of the operation of a continuous extractor.

A simulation of the complete process in Figs. 1 and 2 by extraction of successive batches is more complicated. However, the four-step process of Fig. 1 can be simulated by collecting four batches of extract solution fractions, conducting extract solution from steps IV to II to I, and performing the cooling, mixing, recirculation and reheating shown in Fig. 1. Similarly, the three-step process can in Fig. 2 is simulated by accumulating three batches of extract solution fractions.

The parameters that determine the stationary state in an extraction step consist of the temperature, the ratio of solvent to feed material, and the retention time. A simulation of the processes in Figs. 1 and 2 is more complicated, since additional parameters must be selected, such as the solvent flow in the two lines 2 and l1 and the lines 22 and 37, the flow of recycled solution in the lines 15 and 53, the temperature of the two lines. the phase current in lines 6 and 36, and the residence time in each of the steps in Figs. 1 and 2.

Full fat shell soybean flakes were extracted by the process of Fig. 1. In a series of successive batches, flakes were first soaked in the solution corresponding to that in line 15 (Fig. 1) for 10 minutes and then poured into a vertical glass tube, closed at bottom of a strainer. Each batch was treated immediately with aqueous ethanol solutions as in Fig. 1.

The residence time in step I was half an hour, and in each of the other steps one hour. The experiments were based on the following additional parameters shown in the following Table I, using 100 kg of flakes as a basis: Table I Leads 2 6 13 lä l? Temperature OC boiling H3 boiling 55 55 Flow (kg) 150 800 50 Ethanol content (weight percent) 92 - 8.0 - When a steady state was reached, the various currents were measured and are given in the following Table II: PQQE QUELITYÅ> '(Le : ¶7¶ooÛe 9 m Table II Wires 15 9 H 8 3 herring (kg) 160 21.5 883 861 116.5 Loose material (weight percent) 8.0 - ~ - - Lipids (weight percent) 2.0 - 3.3 1.1 0.5 * Ethanol content (weight percent) 59.0 - 89.9 = - Volatile material (weight percent) - 8.5 - - 50 Proteins (weight percent) 0.50 = - - 6 Å, lx x On a dry basis The only visible difference between this product and that described in Swedish patent application 7609766-6, in which more alcohol was used for step I, was that particles with a shell which had not been completely removed 1 the peeling step before the flake production 5 was not so well discolored in the present example.

Example 2. Full fat shell-free soybean flakes were extracted by the method of Fig. 2. In a series of successive batches, flakes were pre-soaked in a solution, equivalent to that in line 15 for 5 minutes, and then loaded into a vertical glass tube, closed 10 at the bottom by means of a strainer. Each batch was successively treated with strong, aqueous ethanol solutions as in Fig. 2. The residence time in step II was one hour, and in steps III and IV each half an hour.

The experiments were based on the following additional parameters given in the following Table III, using as a basis 15 l00 kg of flakes: Table III Line 22 26 33 37 Temperature ° c boiling M3 boiling boiling Herring (kg) 125 - 800 - Ethanol content (weight percent .) 92 When steady state was reached, the various currents were measured as indicated in the following Table IV: _? (3c§š_c fl3 ëJà fi ñ: l 10 15 20 25 7713304-9 ll Table IV Line 35 29 2H 28 23 Flow (kg) 69.0 21.5 883 861 lÄ0 Solute (weight percent) 8.3 Lipids (weight percent) 6.8 3.3 1.1 0.5 * Ethanol content (weight percent) 77.0 90.1 Volatile material (weight percent) 8.5 50 Protein (weight percent) 0.3 58.3 * x On a dry basis It is to be noted that in this example step II was carried out at the boiling temperature of the aqueous alcohol solvent.The advantages of using high temperature are that water more removed at high temperature than at low, and that in commercial practice a single extractor can be used for all three steps. The present invention relates to the extraction of step II at any desired temperature up to the boiling point of the aqueous alcohol solvent, in order to recover enough oil from stage II as well as from the extract solution in line 19.

These data may form the basis of commercial processes, which include total distillation of solvents from the oil phase in lines 9 or 29, removal of solvents from the extracted flakes in line 3 or 23 for the production of new flours with a high protein content, separation of oil and non-oily lipids from the carbohydrate-enriched extract solution in line 15 (Fig. 1) or line 35 (Fig. 2), and distillation of the extract solution in lines 15 or 35 to recover strong alcohol in lines 2 or 22 and dilute alcohol in line lü (Fig. 1) as distillates and carbohydrates in non-alcoholic aqueous solutions as bottom products, or distillation of the extract solution in line 35 (Fig. 2) to recover strong alcohol in line 22 as distillates and carbohydrates in non-alcoholic aqueous solutions as bottom products. Distillation of these carbohydrate-containing extract solutions can be carried out in the manner previously described.

Soy protein flour prepared according to the present invention is white, substantially free of lipids and has a protein content which depends on the amount of carbohydrates removed and which increases as the two-step, three-step or four-step embodiment of the invention is used.

Did you go out? Although the process of the invention has been described with reference to aqueous ethanol as the preferred solvent since there are no objections to a food product containing traces thereof, and to soybeans, it will be appreciated that the invention may be applied regardless of the aqueous solvent used and oilseeds being treated.

Pooa QUALITY;

Claims (9)

rs 77133 04-9 Patent claims A method of extracting oily seed material in an extraction zone to produce therefrom a protein flour, characterized in that a) the seed material is brought into countercurrent contact with a first concentrated solution of an alcohol in water having an alcohol content of 50-70% by weight, for extraction of water and at least a part of the lipids, b) an extract solution is withdrawn from step a), c) the seed material from step a) is brought into countercurrent contact with a second, concentrated solution of the alcohol in water to extracting substantially all of the lipids, d) from step c) a lipid-rich extract solution is removed, e) the lipid-rich extract solution is cooled to separate a solvent phase and a lipid phase, f) all or a large proportion of the solvent phase is returned to the process and the remaining lipid phase the portion of the solvent phase is deducted from the process, and g) the seed material from step c) is freed from solvent to give a protein meal with low lipid content. lt. 2. A method according to claim 1, characterized in that the temperature in step c) is approximately the boiling point of the second, concentrated solution of the alcohol in water. 3. A process according to claim 1, characterized in that the alcohol consists of a monohydric, aliphatic alcohol having 1-N carbon atoms. 4. A process according to claim 3, characterized in that the alcohol is ethanol. 5. A method according to claim H, characterized in that the oily material consists of soybeans. 6. A method according to claim 1, characterized in that the first, concentrated solution of an alcohol in water consists of the entire amount of solvent phase which is returned to the process in step (f). 7. A method according to claim 6, characterized in that the oily material consists of soybeans and the second, concentrated solution consists of an aqueous solution of ethanol, containing at least 92% by weight of ethanol. s P99? QUALITY - 1 .... .2-. . . '= .- ».' .win-lu- w-.LL s: -; - ;;, «: -.-.-, 1-n, _ .. 0 _ 77133 4 9 H 8. A method according to claim 1, characterized in that the first, concentrated solution of an alcohol in water forms part of the solvent phase which is returned to the process in step (f), and the second part is returned to a zone in step ( c) which lies between the starting point of the second, concentrated solution and the point of withdrawal of the lipid-rich extract solution. 9. A method according to claim 8, characterized in that the oily material consists of soybeans and the second, concentrated solution consists of an ethanol solution in water, containing not more than 9% by weight of ethanol. ~. w. r .. ... rz-f-a = '.' a1 - == ': ~' -.- ~ - -