Oilseed cake protein extraction composition

Abstract

A protein extraction composition comprises water, an oilseed cake, an alkali metal salt, and a surfactant, where the weight ratio of the water to the oilseed cake is 10: 1 or less, where the surfactant is selected from the group consisting of ionic surfactants, non-ionic surfactants, and combinations thereof.

Description

BACKGROUND OF THE DISCLOSURE TECHNICAL FIELD

[0001] The present disclosure relates to extraction compositions and, more particularly, to protein extraction compositions for oilseed cakes.

[0002] Introduction

[0003] A variety of oils are produced by pressing oilseed cakes until the oil is released. Although called "oilseed cakes", such cakes typically include legumes and / or seeds such as cottonseed, castor bean, and soybean. Traditionally, the plant material and pulp remaining after pressing the oilseed cake have been discarded as waste, but recently there has been a push to utilize this material to increase the sustainability of the practice and also extract additional value from the cake. The pulp and plant material contain a variety of recyclable beneficial products such as protein, crude fiber, and essential minerals (e.g., calcium, potassium, phosphorus, and magnesium); however, the removal of the products is difficult and expensive.

[0004] One material of particular interest in oilseed cakes is protein, as it can be used in fertilizers and animal feedstock. Various attempts have been made to extract protein from seed oil cakes. Generally, a protein extraction of 75% or higher, measured according to the Kjeldahl Method, is necessary to achieve an economically viable process. Due to the unique properties of proteins, removing proteins from oilseed cakes is challenging both economically and technically. For example, the macromolecular structure of proteins enables them to reversibly transition between a folded state and an unfolded state. An alkaline extraction medium enables proteins to transition to their unfolded (i.e., denatured) state and be more readily soluble in the medium and removed from the seed oil cake. Generally, a larger protein extraction is achieved with a higher pH (i.e., 13 and higher) of the extraction medium. The extraction medium for protein extraction presents several technical and manufacturing problems. For example, using an extraction medium requires the use of large amounts of alkaline materials (e.g., caustic soda). In addition, the greater the amount of alkaline material used in the extraction medium, the more extensive the remediation that must be carried out before it can be processed. The use of large amounts of alkaline materials and the associated remediation methods increase the cost of protein extraction. Therefore, it would be beneficial to find a recovery method that can be carried out with less alkaline material than traditional methods.

[0005] In addition to the pH of the extraction medium, the extraction of protein from oilseed cakes also depends on the weight ratio of water to oilseed cake in the extraction medium. A weight ratio of water to oilseed cake of 10:1 is typically used to achieve sufficient mixing to increase protein extraction; however, such a large water requirement results in a more expensive and less eco-friendly recovery method. Therefore, a protein extraction method that utilizes a weight ratio of water to oilseed cake of 10:1 or less while maintaining a protein extraction of 75% or greater would be advantageous.

[0006] In view of the above, it is surprising to find a composition that achieves 75% or better protein extraction while using less alkaline material than conventional protein extraction and utilizing a water to oilseed cake weight ratio of 10:1 or less. Summary of the Invention

[0007] The inventors of the present disclosure have discovered a composition that achieves 75% or better protein extraction while using less alkaline material than conventional protein extraction and utilizing a water to oilseed cake weight ratio of 10:1 or less.

[0008] The present disclosure is the discovery that introducing a surfactant into the extraction medium not only reduces the amount of alkaline material required to achieve 75% or higher protein extraction, but also enables a water to oilseed cake weight ratio of 10:1 or less. Without being bound by theory, it is believed that introducing a surfactant into the extraction medium increases the solubility of the protein in the extraction medium. Specifically, it is believed that the surfactant forms micellar structures that bind to multiple sites on the folded protein and dissolve the protein into the extraction medium. By increasing the solubility of the folded protein in the extraction medium, both the alkalinity of the extraction medium and the water to oilseed cake weight ratio can be reduced.

[0009] According to a first aspect of the present disclosure, a protein extraction composition comprises water, an oilseed cake, an alkali metal salt, and a surfactant, wherein the weight ratio of water to oilseed cake is 10:1 or less, and wherein the surfactant is selected from the group consisting of ionic surfactants, non-ionic surfactants, and combinations thereof.

[0010] According to a second aspect of the present disclosure, the alkali metal salt is selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and / or combinations thereof.

[0011] According to a third aspect of the present disclosure, the pH of the protein extraction composition is from 8 to 12.

[0012] According to a fourth aspect of the present disclosure, the weight ratio of water to oilseed cake is from 5:1 to less than 10:1.

[0013] According to a fifth aspect of the present disclosure, the oilseed cake comprises pressed castor seeds.

[0014] According to a sixth aspect of the present disclosure, the surfactant is a non-ionic surfactant.

[0015] According to a seventh aspect of the present disclosure, the surfactant is an ionic surfactant.

[0016] According to an eighth aspect of the present disclosure, the protein extraction composition comprises from 0.01 wt% to 1.5 wt% of the surfactant, based on the total weight of the protein extraction composition.

[0017] According to a ninth feature of the present disclosure, the surfactant comprises one or more of structures (I) to (III), wherein for structure (I), the average m value is 5 and the average n value is from 3 to 9, wherein for structure (II), the average n value is from 1 to 4, and wherein for structure (III), R1 and R2 are each independently selected from H and C5-C 20 alkyl, and further wherein each M + is independently selected from the group consisting of Li, K, and Na.

[0018] According to a tenth feature of the present disclosure, the surfactant comprises both structure (I) and structure (II). Detailed Description

[0019] As used herein, the term “and / or” when used in a list of two or more items means that any one of the listed items can be used alone, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0020] Unless otherwise stated, all ranges include the endpoints.

[0021] As used herein, unless otherwise stated, the term weight percentage (“wt%”) represents the weight percentage of a part in the total weight of a defined whole.

[0022] As used herein, the Chemical Abstracts Service Registry Number (“CAS#”) refers to the unique numerical identifier most recently assigned by the Chemical Abstracts Service to a chemical compound since the priority date of this document.

[0023] Protein extraction composition

[0024] The present disclosure relates to a protein extraction composition (“composition”). The composition comprises water, oilseed cake, an alkali metal salt, and a surfactant. As described above, the protein extraction composition is designed to extract residual protein from the oilseed cake, thereby increasing the recovery rate of the material from the oilseed cake.

[0025] The composition comprises 70% to 98% by weight of water based on the total weight of the composition. For example, the composition may comprise 70% by weight or more, or 72% by weight or more, or 74% by weight or more, or 76% by weight or more, or 78% by weight or more, or 80% by weight or more, or 82% by weight or more, or 84% by weight or more, or 86% by weight or more, or 88% by weight or more, or 90% by weight or more, or 92% by weight or more, or 94% by weight or more, or 96% by weight or more of water, while at the same time, 98% by weight or less, or 96% by weight or less, or 94% by weight or less, or 92% by weight or less, or 90% by weight or less, or 88% by weight or less, or 86% by weight or less, or 84% by weight or less, or 82% by weight or less, or 80% by weight or less, or 78% by weight or less, or 76% by weight or less, or 74% by weight or less, or 72% by weight or less of water.

[0026] The composition has a hydrogen potential (pH) of 8.0 to 13.0 as measured according to ASTM D1293. For example, the composition may have a pH of 8.0 or greater, or 8.2 or greater, 8.4 or greater, or 8.6 or greater, or 8.8 or greater, or 9.0 or greater, or 9.2 or greater, 9.4 or greater, or 9.6 or greater, or 9.8 or greater, or 10.0 or greater, or 10.2 or greater, 10.4 or greater, or 10.6 or greater, or 10.8 or greater, or 11.0 or greater, or 11.2 or greater, 11.4 or greater, or 11.6 or greater, or 11.8 or greater, or 12.0 or greater, or 12.2 or greater, 12.4 or greater, or 12.6 or greater, or 12.8 or greater as measured according to ASTM D1293, while at the same time, 13.0 or less, or 12.8 or less, or 12.6 or less, or 12.4 or less, or 12.2 or less, or 12.0 or less, or 11.8 or less, or 11.6 or less, or 11.4 or less, or 11.2 or less, or 11.0 or less, or 10.8 or less, or 10.6 or less, or 10.4 or less, or 10.2 or less, or 10.0 or less, or 9.8 or less, or 9.6 or less, or 9.4 or less, or 9.2 or less, or 9.0 or less, or 8.8 or less, or 8.6 or less, or 8.4 or less, or 8.2 or less of pH.

[0027] Oilseed cake

[0028] The composition contains oilseed cake. As used herein, the term "oilseed cake" encompasses all cakes, pulps, meals, and other residual plant materials remaining after plant material has been pressed or otherwise processed for oil extraction. Although the term "seed" is used, oilseed cake includes plant material from seeds, beans, fruits, hulls, plant bodies, and other plant-based materials. Exemplary materials that can be used to form oilseed cake include soybeans, castor beans, peanuts, cottonseed, rapeseed, sunflower and sunflower seeds, oil palm, groundnuts, coconuts, palm kernels, flaxseed, sesame seeds, and the like. In a specific example, the oilseed cake contains pressed castor beans.

[0029] The composition may contain from 1% to 20% by weight of water, based on the total weight of the composition. For example, the composition may contain 1% by weight or more, or 2% by weight or more, or 4% by weight or more, or 6% by weight or more, or 8% by weight or more, or 10% by weight or more, or 12% by weight or more, or 14% by weight or more, or 16% by weight or more, or 18% by weight or more of the oilseed cake, while at the same time containing 20% by weight or less, or 18% by weight or less, or 16% by weight or less, or 14% by weight or less, or 12% by weight or less, or 10% by weight or less, or 8% by weight or less, or 6% by weight or less, or 4% by weight or less, or 2% by weight or less of water.

[0030] The composition may have a weight ratio of water to oilseed cake of 20:1 or less. For example, the weight ratio of water to oilseed cake may be 20:1 or less, or 19:1 or less, or 18:1 or less, or 17:1 or less, or 16:1 or less, or 15:1 or less, or 14:1 or less, or 13:1 or less, or 12:1 or less, or 11:1 or less, or 10:1 or less, or 9:1 or less, or 8:1 or less, or 7:1 or less, or 6:1 or less, or 5:1 or less, or 4:1 or less, or 3:1 or less, or 2:1 or less, or 1:1 or less.

[0031] Alkali metal salt

[0032] When extracting protein, the composition has a pH that is generally basic and is controlled by adding an alkali metal salt. The alkali metal salt may be selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and / or combinations thereof. The alkali metal salt can be added to the composition as such and / or as an aqueous solution.

[0033] The composition may contain an alkali metal salt in an amount of 0.01 wt% or more, or 0.02 wt% or more, or 0.04 wt% or more, or 0.06 wt% or more, or 0.08 wt% or more, or 0.10 wt% or more, or 0.20 wt% or more, or 0.30 wt% or more, or 0.40 wt% or more, or 0.50 wt% or more, or 0.60 wt% or more, or 0.70 wt% or more, or 0.80 wt% or more, or 0.90 wt% or more, or 1.00 wt% or more, or 2.00 wt% or more, or 3.00 wt% or more, or 4.00 wt% or more, while at the same time 5.00 wt% or less, or 4.00 wt% or less, or 3.00 wt% or less, or 2.00 wt% or less, or 1.00 wt% or less, or 0.50 wt% or less, or 0.10 wt% or less, or 0.05 wt% or less, or 0.02 wt% or less, based on the total weight of the composition.

[0034] Surfactant

[0035] The composition extracts residual proteins from oilseed cakes using a surfactant. The surfactant is selected from the group consisting of ionic surfactants, non-ionic surfactants, and combinations thereof. In a non-ionic example of the surfactant, the surfactant may comprise structure (I)

[0036]

[0037] The average value of m for structure (I) can be from 1 to 10, and the average value of n can be from 1 to 20. For example, the average value of m for structure (I) can be 1 or greater, or 2 or greater, or 3 or greater, or 4 or greater, or 5 or greater, or 6 or greater, or 7 or greater, or 8 or greater, or 9 or greater, and at the same time, 10 or less, or 9 or less, or 8 or less, or 7 or less, or 6 or less, or 5 or less, or 4 or less, or 3 or less, or 2 or less. The average value of n for structure (I) can be 1 or greater, or 2 or greater, or 3 or greater, or 4 or greater, or 5 or greater, or 6 or greater, or 7 or greater, or 8 or greater, or 9 or greater, or 10 or greater, or 11 or greater, or 12 or greater, or 13 or greater, or 14 or greater, or 15 or greater, or 16 or greater, or 17 or greater, or 18 or greater, or 19 or greater, and while at the same time, 20 or less, or 19 or less, or 18 or less, or 17 or less, or 16 or less, or 15 or less, or 14 or less, or 13 or less, or 12 or less, or 11 or less, or 10 or less, or 9 or less, or 8 or less, or 7 or less, or 6 or less, or 5 or less, or 4 or less, or 3 or less, or 2 or less. Any combination of the m value and the n value of structure (I) can be combined and is hereby disclosed.

[0038] In an example of a nonionic surfactant, the surfactant can be an alkyl polyglucoside. An exemplary polyglucoside is provided in structure (II)

[0039]

[0040] where the average value of n for structure (II) is from 1.00 to 4.00. For example, the average value of n for structure (II) can be 1.00 or greater, or 1.25 or greater, or 1.50 or greater, or 1.75 or greater, or 2.00 or greater, or 2.25 or greater, or 2.50 or greater, or 2.75 or greater, or 3.00 or greater, or 3.25 or greater, or 3.50 or greater, or 3.75 or greater, and at the same time, 4.00 or less, or 3.75 or less, or 3.50 or less, or 3.25 or less, or 3.00 or less, or 2.75 or less, or 2.50 or less, or 2.25 or less, or 2.00 or less, or 1.75 or less, or 1.50 or less, or 1.25 or less, as determined by C 13Measured by nuclear magnetic resonance. In other words, the alkyl moiety of structure (II) can have from 4 to 16 carbons. Specifically, the alkyl moiety of structure (II) can have 4 or more carbons, or 5 or more carbons, or 6 or more carbons, or 7 or more carbons, or 8 or more carbons, or 9 or more carbons, or 10 or more carbons, or 11 or more carbons, or 12 or more carbons, or 13 or more carbons, or 14 or more carbons, or 15 or more carbons, while at the same time, 16 or fewer carbons, or 15 or fewer carbons, or 14 or fewer carbons, or 13 or fewer carbons, or 12 or fewer carbons, or 11 or fewer carbons, or 10 or fewer carbons, or 9 or fewer carbons, or 8 or fewer carbons, or 7 or fewer carbons, or 6 or fewer carbons, or 5 or fewer carbons, as measured by C 13 Measured by nuclear magnetic resonance.

[0041] In the example of an ionic surfactant, the surfactant can be an alkylated diphenyl ether disulfonate, such as provided in structure (III)

[0042]

[0043] wherein R1 and R2 are each independently selected from H or C5-C 20 alkyl; for example, each of R1 and R2 can independently be a C5 alkyl, or a C6 alkyl, or a C7 alkyl, or a C8 alkyl, or a C9 alkyl, or a C 10 alkyl, or a C 11 alkyl, or a C 12 alkyl, or a C 13 alkyl, or a C 14 alkyl, or a C 15 alkyl, or a C 16 alkyl, or a C 17 alkyl, or a C 18 alkyl, or a C 19 alkyl, or a C 20 alkyl. R1 and R2 can each independently be a straight-chain or branched-chain alkyl. Each M of structure (III) + is independently selected from the group consisting of Li, K, and Na. The surfactant can comprise a variety of different compounds, all related to structure (III), but with different options for the selected R1, R2, and M + selected.

[0044] Additionally or alternatively, the surfactant can comprise one or more of the following: seed alcohol alkoxylates, secondary alcohol ethoxylates, ethylene oxide and propylene oxide copolymers, and / or fatty alcohol alkoxylates, wherein the alkyl chain has from 8 to 18 carbon atoms.

[0045] The composition may comprise from 0.01% to 5% by weight of a surfactant based on the total weight of the composition. The composition may comprise 0.01% by weight or more, or 0.02% by weight or more, or 0.04% by weight or more, or 0.06% by weight or more, or 0.08% by weight or more, or 0.10% by weight or more, or 0.20% by weight or more, or 0.30% by weight or more, or 0.40% by weight or more, or 0.50% by weight or more, or 0.60% by weight or more, or 0.70% by weight or more, or 0.80% by weight or more, or 0.90% by weight or more, or 1.00% by weight or more, or 2.00% by weight or more, or 3.00% by weight or more, or 4.00% by weight or more of a surfactant, while, at the same time, 5.00% by weight or less, or 4.00% by weight or less, or 3.00% by weight or less, or 2.00% by weight or less, or 1.00% by weight or less, or 0.50% by weight or less, or 0.10% by weight or less, or 0.05% by weight or less, or 0.02% by weight or less of a surfactant.

[0046] As explained above, the surfactant may comprise one or more different types of surfactants. In examples where there is more than one type of surfactant, each surfactant may independently be 1% by weight or more, or 5% by weight or more, or 10% by weight or more, or 15% by weight or more, or 20% by weight or more, or 25% by weight or more, or 30% by weight or more, or 35% by weight or more, or 40% by weight or more, or 45% by weight or more, or 50% by weight or more, or 55% by weight or more, or 60% by weight or more, or 65% by weight or more, or 70% by weight or more, or 75% by weight or more, or 80% by weight or more, or 85% by weight or more, or 90% by weight or more, or 95% by weight or more, or 99% by weight or more of the total amount of surfactants used in the composition.

[0047] Protein extraction

[0048] The composition may be effective in extracting residual protein from oilseed cake. As measured by the Kjeldahl method, the composition may extract 75% or more, or 80% or more, or 85% or more, or 90% or more, or 95% or more, or 98% or more of the protein from the oilseed cake.

[0049] Examples

[0050] Materials

[0051] The following materials were used in the examples.

[0052] SURF1 is 99 wt% of Structure (I) where the average m value is 5, the average n value is from 3 to 9, and it is commercially available from Dow Chemical Company, Midland, Michigan.

[0053] SURF2 is an 80 wt% aqueous solution of sodium laureth - 2 sulfate, CAS# 3088 - 31 - 1, and it is commercially available from Sigma Aldrich, St. Louis, Missouri.

[0054] SURF3 is a 46 wt% aqueous solution of Structure (III) where each M + is Na, R1 is H, and R2 is a C 16 linear alkyl. SURF3 is available from Dow Chemical Company, Midland, Michigan.

[0055] SURF4 is a 50 wt% aqueous solution of Structure (II) with an average n value from 2 to 2.5 and it is commercially available from Dow Chemical Company, Midland, Michigan.

[0056] OSC is 100% castor powder in powder form with a diameter of 500 microns or less, and it is commercially available from Jayant Agro - Organics, Mumbai, India.

[0057] NaOH is a sodium hydroxide solution and it is commercially available from Sigma Aldrich, St. Louis, Missouri.

[0058] Sample preparation

[0059] Samples are prepared by placing a specified amount of OSC and deionized water in a container and stirring with a overhead stirrer at 500 revolutions per minute for 10 minutes. Next, a specified amount of 25 wt% NaOH aqueous solution is added to the sample after stirring. Then, the specified surfactant is added to the sample in the specified dosage and stirred with an overhead stirrer at 500 revolutions per minute for 90 minutes. Finally, the supernatant is poured out and the protein content is measured according to ASTM D3590. Three samples of each example are prepared.

[0060] Testing methods

[0061] Kjeldahl method : First, the total nitrogen content of the supernatant is determined according to ASTM D3590. Next, the nitrogen content (in percentage) is multiplied by a protein factor of 6.25 to determine the final protein content extracted in percentage.

[0062] Hydrogen potential: Measured according to ASTM D1293.

[0063] Results

[0064] Tables 1 to 3 provide the results of various comparative examples (“CE”) and examples of the present invention (“IE”). Table 1 provides the results of examples using 10 grams of water mixed with 10 grams of OSC and the other listed components. The initial pH is before the addition of the 25 wt% NaOH aqueous solution, and the final pH is the pH after the addition of NaOH.

[0065] Table 1

[0066]

[0067] As can be seen from Table 1, an increased amount of NaOH is required to increase the protein extracted from the OSC. Table 1 is used to set a baseline for the amount of NaOH required to achieve certain protein extractions when no surfactant is used.

[0068] Table 2 provides the results of examples using a surfactant at the same water to OSC ratio as the comparative examples in Table 1.

[0069] Table 2

[0070]

[0071]

[0072] IE1 to IE5 in Table 2 show that the addition of a surfactant enhances protein extraction and uses less NaOH compared to CE5 without a surfactant. When compared to extraction without a surfactant at pH 11 - 13, the blend with the added surfactant in IE3 increases the protein extraction content at a lower pH of about 11. The addition of both anionic and nonionic surfactants in IE1 to IE5 enhances protein extraction at lower NaOH concentrations compared to CE5.

[0073] Table 3 provides examples testing the effect of the water to oilseed cake weight ratio on the final protein extraction percentage.

[0074] Table 3

[0075]

[0076] For CE4 and CE6, when the water content in the composition was reduced from a water to OSC weight ratio of 10:1 to 7:1, the protein content decreased from approximately 92% to approximately 52%, representing a 40% reduction in protein extraction. However, surprisingly, as shown by IE3 and IE6, introducing a surfactant into the composition prevented the sharp reduction in protein extraction seen in CE4 and CE6. Thus, using a defined surfactant in the composition achieved 75% or better protein extraction while using less alkaline material than conventional protein extraction and utilizing a water to oilseed cake weight ratio of 10:1 or less.

Claims

1. A protein extraction composition, comprising: Water; Oilseed cake, wherein the weight ratio of the water to the oilseed cake is 10:1 or less; Alkali metal salt; and Surfactant, wherein the surfactant is selected from the group consisting of ionic surfactants, non-ionic surfactants, and combinations thereof.

2. The protein extraction composition according to claim 1, wherein the alkali metal salt is selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and / or combinations thereof.

3. The protein extraction composition according to one of claims 1 and 2, wherein the pH of the protein extraction composition is 8 to 12.

4. The protein extraction composition according to one of claims 1 to 3, wherein the weight ratio of the water to the oilseed cake is 5:1 to less than 10:

1.

5. The protein extraction composition according to one of claims 1 to 4, wherein the oilseed cake comprises pressed castor seeds.

6. The protein extraction composition according to one of claims 1 to 5, wherein the surfactant is a non-ionic surfactant.

7. The protein extraction composition according to one of claims 1 to 5, wherein the surfactant is an ionic surfactant.

8. The protein extraction composition according to one of claims 1 to 7, wherein the protein extraction composition comprises 0.01 wt% to 1.5 wt% of the surfactant based on the total weight of the protein extraction composition.

9. The protein extraction composition according to any one of claims 1 to 8, wherein the surfactant comprises one or more of structures (I) to (III): wherein for structure (I), the average m value is 5, and the average n value is 3 to 9, wherein for structure (II), the average n value is 1 to 4, For structure (III), R1 and R2 are each independently selected from H and C5-C 20 alkyl, and further wherein each M + is independently selected from the group consisting of Li, K, and Na.

10. The protein extraction composition according to claim 9, wherein the surfactant comprises both structure (I) and structure (II).

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