Method for demulsification by centrifugation, and method for separating vegetable protein

Abstract

To provide: a method for demulsification by centrifugation that is effective for producing vegetable protein with a reduced lipid content; and a method for separating vegetable protein using the method.SOLUTION: Provided is a method for separating and recovering vegetable protein from food materials containing vegetable protein, comprising: an alkaline agitating extraction step of agitating the food materials in an alkaline aqueous solution; a solid-liquid separation step of separating the mixed solution obtained after the alkaline agitating extraction step, into solid components and emulsified components; a demulsification step of demulsifying, by centrifugation, the emulsified components separated in the solid-liquid separation step; an acid precipitation step of neutralizing the emulsified components obtained after the demulsification step, to produce crude protein gel; and a crude protein gel recovery step of recovering the crude protein gel produced in the acid precipitation step. In the demulsification step, vegetable oil is added to the emulsion components, and then, the centrifugation is performed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a demulsification method by centrifugation and a method for separating vegetable protein using the same, and more particularly to a demulsification method by centrifugation effective for producing protein from plant raw materials containing oil and fat such as rice bran and soybeans, and a method for separating vegetable protein using the same.

Background Art

[0002] In recent years, in various foods including processed foods, interest in vegetable proteins such as soy protein has been increasing. Such vegetable proteins are foods obtained by separating or concentrating proteins contained in plants, and are widely used in meat processed products, fishery processed products, foods for specified health uses, etc. In recent years, they are also used in beer-flavored foaming alcoholic beverages (third beer) and foods for the elderly (enteral nutritional agents). In addition, such vegetable proteins are also regarded as important alternative meats in times of shortage of livestock meat raw materials. Such vegetable proteins are classified into four types: granular, powdery, paste-like, and fibrous, depending on their shape and physical properties. Granular and fibrous vegetable proteins are used to improve the texture of hamburgers, etc., powdery vegetable proteins are used for nutritional enhancement and texture improvement, etc., and paste-like vegetable proteins are used as binders, etc.

[0003] Regarding such vegetable proteins, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2012-228275), in order to efficiently separate lipids from defatted soybeans without relying on organic solvents and provide a defatted soy protein material with reduced lipids, as its production method, defatted soybeans processed with an NSI in the range of 20 to 77 and not extracted with an organic solvent are used. A method for producing a defatted soy protein material is proposed, which includes 1) a step of adding water to the defatted soybeans to prepare a suspension, and 2) a step of solid-liquid separating the suspension to transfer and remove neutral lipids and polar lipids to an insoluble fraction and recover a water-soluble fraction containing protein and carbohydrates.

[0004] In Patent Document 2 (Japanese Patent Laid-Open No. 2012-110), in order to increase the protein recovery rate when separating protein from food, a protein extraction solution acquisition step of adjusting the pH in the medium of the raw food to extract the protein, a protein acid precipitation step of adjusting the pH of the protein extraction solution to the isoelectric point of the protein to be separated to precipitate the protein, and a protein recovery step of centrifuging the precipitated protein to separate the protein precipitation filtrate and recovering the precipitated protein are included. In the protein separation method by acid precipitation, a protein heating precipitation step of heating the protein extraction solution or the protein precipitation filtrate to 60 to 145°C to precipitate the protein is further proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the above Patent Document 1, it is proposed to efficiently separate lipids from defatted soybeans. However, since the raw material is defatted soybeans processed with an NSI in the range of 20 to 77, it is difficult to use in other foods. Also, in this Document 1, regarding the method of separating, by centrifugation, an emulsion (cream) rich in lipids to float to the upper layer and separating it into soy milk with less lipids and the emulsion, the lipids emulsified in the soy milk have a small particle size and a high centrifugal force (G) is required for separation, which is not suitable for mass production. Moreover, even with a high centrifugal force, the actual separation efficiency is low, and it has been shown that it is difficult to highly separate the lipids in the soy milk.

[0007] In Patent Document 2, it is disclosed that milk, beans, rice bran, or fish meat is used as the food raw material. However, after the protein extract acquisition stage, a protein acid precipitation stage is carried out, and the precipitated protein is recovered by centrifugation. Since the oil and fat content is not recovered, the produced protein contains a large amount of oil and fat.

[0008] Here, when considering the storage stability of the produced protein, it is desirable that the oil and fat content is low. Therefore, in the present invention, an effective demulsification method by centrifugation for producing vegetable protein with a reduced oil and fat content, and a separation method of vegetable protein using this method are provided. Another object is to provide vegetable protein with a reduced oil and fat content.

[0009] In addition, in the present invention, another object is to provide a purification technique for vegetable protein that increases the yield and purity of the produced crude protein gel, and is suitable for commercialization, particularly for alternative meat processing with a low denaturation rate.

Means for Solving the Problems

[0010] In order to solve at least one of the above problems, the present invention provides a demulsification method by centrifugation capable of efficiently and stably recovering oil and fat from an emulsified component containing vegetable protein by centrifugation, a separation method of vegetable protein using this demulsification method, and vegetable protein with a reduced oil and fat content produced by this separation method.

[0011] That is, the demulsification method by centrifugation according to the present invention is a demulsification method for separating oil and fat from an emulsified component containing at least vegetable protein, characterized in that vegetable oil such as vegetable oil, particularly preferably refined vegetable oil, is added to the emulsified component and then centrifugation is performed.

[0012] In such a demulsification method, the vegetable oil or fat added to the liquid emulsified component is not particularly limited as long as it is a vegetable oil or fat (especially oil), but it is preferably the same as the vegetable oil or fat (especially oil) that appears by demulsification. This is because the oil or fat recovered by demulsification can be utilized.

[0013] Also, in the present invention, in order to solve any of the above problems, there is provided a method for separating vegetable protein using the demulsification method by centrifugation.

[0014] That is, there is provided a method for separating vegetable protein for separating and recovering vegetable protein from a food containing vegetable protein, which comprises an alkali extraction step of stirring the raw material food in an aqueous alkali solution, a solid-liquid separation step of separating the mixed solution after the alkali extraction step into a solid component and an emulsified component, a demulsification step of demulsifying the emulsified component separated in the solid-liquid separation step by centrifugation, an acid precipitation step of lowering the pH of the emulsified component after the demulsification step to produce a crude protein gel, and a crude protein gel recovery step of recovering the crude protein gel produced in the acid precipitation step, wherein the demulsification step is performed by the demulsification method by centrifugation of the present invention.

[0015] In the method for separating vegetable protein of the present invention described above, the food is a plant or a food derived from a plant, and examples thereof include oilseed grains such as soybeans, peas, rapeseeds, cottonseeds, peanuts, sesame seeds, safflower, sunflowers, corn, safflowers, coconuts, or cereal seeds such as rice, barley, and wheat. In terms of ease of availability and economy, rice bran and soybean materials are preferable. Here, the soybean material may be any material containing soybean-derived protein, and examples thereof include whole soybeans such as whole soybeans and split soybeans, defatted soybeans and defatted soybeans from which oil has been removed, concentrated soybeans or soy milk in which protein has been concentrated by washing with aqueous ethanol or acid washing, and their hydrolysates, okara, whey, etc., and at least one of these can be selected. In particular, it is preferable to use rice bran or defatted soybeans from the viewpoint of cost. Also, the demulsification step is preferably carried out at a centrifugal acceleration of 1,000 g or more, more preferably 2,000 g or more, and particularly preferably 3,000 g or more.

[0016] In addition, the present invention provides a method for adjusting the oil and fat content of vegetable protein by utilizing the method for separating vegetable protein to solve any of the above problems.

[0017] That is, a method for adjusting the oil and fat content of vegetable protein, which adjusts the oil and fat content in the vegetable protein separated and recovered from food containing vegetable protein, is characterized in that it is produced by the method for separating vegetable protein according to the present invention, and adjusts the oil and fat content in the vegetable protein separated and recovered by the centrifugal acceleration of centrifugation in the demulsification step.

[0018] And in the present invention, in order to solve any of the above problems, a vegetable protein with a low oil and fat content is provided.

[0019] That is, a vegetable protein formed using rice bran or soybeans, wherein the oil and fat content is 32 wt% or more and 50 wt% or less in the vegetable protein formed using rice bran, and 13 wt% or more and 28 wt% or less in the vegetable protein formed using soybeans, and is low-denatured, and the protein content excluding the oil and fat is 65 wt% or more and 85 wt% or less. Further, the present invention can provide a vegetable protein with an extremely low salt content compared to that obtained by demulsification with the addition of inorganic salts.

[0020] The low-denatured state can be indicated by the ratio of the secondary structure of the protein being attributed to an irregular structure being less than 20% in FT-IR absorption spectrum analysis. That is, the index of the low denaturation is the amide I band (1600 - 1700 cm -1It can be determined by the analysis of -1 ). That is, it can be confirmed by the secondary structure analysis of the protein based on the analysis of the C=O stretching vibration (amide I) band appearing in the infrared absorption spectrum. The analysis method is curve fitting, which finely divides the amide I band, and when the ratio attributable to β-sheet (1610~1640 cm -1 ), α-helix, and random coil (1640~1660 cm -1 ) is 80% or more, it can be determined that it is low-denatured. The denatured part is attributed to (1660 cm -1 or more and 1700 cm -1 or less). Therefore, when the absorption spectrum of the amide I band (1600~1700 cm -1 ) of FT-IR is subjected to curve fitting analysis, when the ratio attributed to 1610~1660 cm

Advantages of the Invention

[0021] In the demulsification method by centrifugation of the present invention, since plant oil (especially oil) is added to the emulsified component and then centrifugation is performed, the oil and fat component that appears in the demulsification by centrifugation is transferred to the added plant oil side and will not return to the aqueous layer again, and the stability after demulsification can be enhanced. As a result, an aqueous layer (emulsion) with extremely reduced oil and fat content can be obtained.

[0022] Also, according to the method for separating vegetable protein using the demulsification method, the plant oil contained in the emulsified component after the solid-liquid separation step can be demulsified by the centrifugation and retained on the plant oil side, so that the oil and fat content in the produced crude protein gel can be reduced.

[0023] Furthermore, in the demulsification by the centrifugation, since the amount of the oil and fat component to be separated can be adjusted by the centrifugal acceleration of the centrifugation, the oil and fat content in the produced vegetable protein can also be adjusted.

[0024] And since the vegetable protein according to the present invention uses rice bran or soybeans as raw food, the oil content can be set to 32 wt% or more and 50 wt% or less in the vegetable protein formed using rice bran, and 13 wt% or more and 28 wt% or less in the vegetable protein formed using soybeans according to the manufacturing method of the present invention. The protein content excluding the oil content can be set to 65 wt% or more and 85 wt% or less.

Brief Description of Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0026] Hereinafter, with reference to the drawings, the demulsification method by centrifugation according to the present embodiment and the separation method of vegetable protein using the same will be specifically described. In particular, the present embodiment shows an example of manufacturing vegetable protein using oilseed grains such as rice bran or soybeans and grains.

[0027] FIG. 1 is a flowchart showing the manufacturing process of vegetable protein according to the first embodiment, and particularly shows an example using rice bran as food.

[0028] 〔Alkali Extraction Step〕 First, an alkali extraction step is carried out in which rice bran used as a raw material is stirred in an aqueous alkali solution. As the raw material rice bran, raw rice bran, pressed (semi) defatted rice bran, etc. can be used. Also, as the aqueous alkali solution, hydroxides and carbonates of alkali metals and alkaline earth metals, bicarbonates, calcined calcium, ammonia, aqueous solutions of amines, kansui, etc. can be used. In this embodiment, a 0.2% sodium aqueous solution is used. And the stirring of the rice bran and the aqueous alkali solution is carried out at room temperature in this embodiment, but it can also be carried out in a temperature range of 10°C or higher and 45°C or lower. If it is less than 10°C, the extraction efficiency decreases, and if it exceeds 45°C, protein denaturation progresses. Also, the stirring time can be arbitrary, but it is preferably 0.5 hours or more and 6 hours or less. This is because if it is less than 0.5 hours, the extraction is likely to be insufficient, and if it exceeds 6 hours, there is a concern about an increase in impurities due to reactions other than extraction such as hydrolysis.

[0029] 〔Solid-liquid separation step〕 And after the above alkali extraction step, a solid-liquid separation step is carried out in which the mixed solution after stirring is separated into a solid component and an emulsified component. In this solid-liquid separation step, the solid component can be filtered out using a sieve, net, cloth, or filter with an appropriate mesh size according to the particle size and size of the solid component to be filtered, or it can be separated into a solid component and an emulsified component by centrifugation or the like. At this time, since it is conceivable that there is also an oil component in the solid component that is the residue in the filtration, the solid component of the residue can be used as a raw material for extracting active ingredients such as vegetable oils. In this embodiment, since rice bran is used as food, the solid component that is the residue can be used as a raw material for rice oil extraction. And since the target vegetable protein is contained in the emulsified component in the solid-liquid separation step, this is used in the next centrifugation step.

[0030] In addition, in order to reduce the influence on the centrifuge used in the demulsification step to be carried out next, it is desirable to neutralize the separated emulsified component. In this neutralization, although it is conceivable that slight isoelectric precipitation occurs, as long as it is within several hours from the neutralization, the flocculation precipitation does not progress and its influence can be almost ignored.

[0031] 〔Demulsification step〕 In this centrifugation step, the emulsified components separated in the solid-liquid separation step are demulsified by centrifugation. As demulsification methods, in addition to centrifugation, addition of inorganic salts, phase transition due to temperature change, liquid membrane formation filtration, application of alternating electric field, HLB shift by surfactant, dissolution / inactivation by addition of solvent can be considered. However, in demulsification by addition of inorganic salts, the produced vegetable protein becomes a gel containing a large amount of salts, and in demulsification by phase transition due to temperature change, protein denaturation occurs under severe conditions. Also, demulsification by liquid membrane formation filtration or application of alternating electric field cannot be said to be simple and is also costly. And in demulsification by HLB shift with surfactant, the produced vegetable gel is not desirable as a food, and in dissolution / inactivation by addition of solvent, protein denaturation occurs, so it cannot be said to be preferable.

[0032] In the present embodiment, during this centrifugation, vegetable oil and fat (especially oil) is added to the emulsified components before performing the centrifugation. By adding such vegetable oil and fat (especially oil), the oil and fat components that appear during demulsification can be transferred to the added vegetable oil and fat, and since the added vegetable oil and fat holds the demulsified oil and fat components, it is possible to prevent the oil and fat components from returning to the emulsified component side again. Thereby, the oil and fat components in the emulsified components can be reduced. It is desirable that the vegetable oil and fat used in such demulsification step be the same as the oil and fat components contained in the emulsified components, that is, the oil and fat components in the raw food, but it is not limited thereto and other vegetable oil and fat may also be used.

[0033] In this embodiment, since rice bran is used as the raw material food, rice bran oil is used as the vegetable oil added in this centrifugation step. As a result, the oil component separated in the demulsification step can be utilized as rice bran oil. Also, the oil component added in this demulsification fixing can be set to 3 wt% or more and 100 wt% or less with respect to the target emulsifying component. If it is less than 3 wt%, it becomes difficult to hold the transferred demulsified oil, and if it exceeds 100 wt%, the centrifugation efficiency decreases, leading to a loss of vegetable oil. When no oil component is added in the demulsification step, the demulsification is unstable and easily dispersed. Especially when using rice bran as the raw material food, the affinity between rice bran protein and oil is high, and the demulsified state becomes more unstable.

[0034] Also, the centrifugation carried out in this demulsification step is preferably performed at a centrifugal acceleration of 1,000 g or more. This is because if the centrifugal acceleration is less than 1,000 g, the amount of oil component separated from the emulsifying component is small, and it is difficult to perform sufficient demulsification. Also, the separation amount of the oil component in the demulsification step is correlated with the centrifugal acceleration in this centrifugation. Therefore, by adjusting the centrifugal acceleration, the oil component in the emulsifying component can be adjusted, and as a result, the oil component content in the crude protein gel and vegetable protein produced in the subsequent steps can be adjusted.

[0035] And although the processing time of centrifugation depends on the target liquid, in this embodiment, it is preferably 3 minutes or more and 20 minutes or less. This is because if it is less than 3 minutes, sufficient demulsification cannot be achieved, and if it exceeds 20 minutes, aggregation and sedimentation of proteins due to centrifugal force will occur.

[0036] 〔Acid precipitation step〕 In the demulsification step, the emulsified component with reduced oil and fat content is, in this acid precipitation step, adjusted to a pH corresponding to the protein in the raw food while heating it to a temperature below the temperature at which the protein denatures, thereby producing a crude protein gel. Specifically, an acid is added to adjust the pH of the alkaline aqueous solution used in the stirring step. In this embodiment, since rice bran is used as the raw food, a 6N aqueous citric acid solution is dropped to adjust the pH to 5.5. However, since the purpose is to adjust the pH, other acids may be used. In utilizing the produced vegetable protein as food, the acid used in this acid precipitation step is preferably an acid listed in the food additive list such as adipic acid, L-ascorbic acid, L-aspartic acid, gluconic acid, L-glutamic acid, succinic acid, acetic acid, L- or DL-tartaric acid, sorbic acid, nicotinic acid, lactic acid, phytic acid, fumaric acid, propionic acid, malic acid, phosphoric acid, etc. in addition to citric acid. However, hydrochloric acid, sulfuric acid, oxalic acid, etc. can also be used as long as they can be neutralized or removed before the completion of the final product. After setting the pH to the target value, the temperature is set slightly higher than the temperature at which the protein denatures, and then immediately cooled to produce a crude protein gel in the emulsified component.

[0037] 〔Crude Protein Gel Recovery Step〕 In this crude protein gel recovery step, the crude protein gel produced in the acid precipitation step is recovered. Specifically, the crude protein gel precipitated in the emulsified component is aggregated and separated and recovered, and a sieve, filter, etc. can be used. In addition, a centrifuge, separating funnel, etc. that can separate the water in the emulsified component can also be used. The separated and recovered crude protein gel can also be washed with water as necessary.

[0038] The crude protein gel produced in the above steps can then be made into a vegetable protein product by drying, pulverizing, mixing with other components, etc.

Example

[0039] In the following Example 1, rice bran was used as the raw material food, and vegetable protein was produced based on the manufacturing flow shown in Fig. 1. It will be described based on the photos (Figs. 2 to 9) in each process.

[0040] 〔Alkaline extraction〕 666 g of 0.2% NaOH aqueous solution was added to a 1000 mL beaker (Fig. 2a) and stirred. When 100.0 g of rice bran was gradually added thereto, a yellow suspension was formed (Fig. 2b). It was stirred for about 1 hour (Fig. 2c).

[0041] 〔Solid-liquid separation (filtration, centrifugation)〕 This was filtered through a mesh (Fig. 3a). When the residue was wrung out with a cotton cloth (Fig. 3b), a yellowish-white suspension was obtained (Fig. 3c). It was transferred to three centrifuge bottles (Fig. 3d), and centrifuged for impurity removal (centrifugation at 2,200 g for 3 minutes), and fine bran residues and white starch particles were precipitated at the bottom (Fig. 3e). The supernatant was a yellow opaque solution. At this time, since a little oil and fat had separated on the liquid surface (Figs. 3f, g), the retention time of the separation state was measured. At 15 minutes, the boundary between the demulsified oil and fat and the oil film became ambiguous, and at 30 minutes, it was dispersed on the liquid surface to a state closer to uniform (Fig. 4a). At 40 minutes, it was completely uniformly dispersed on the liquid surface (Fig. 4b). However, it was on the liquid surface (Fig. 4c), and there was almost no leaching into the water layer, but it was in a difficult-to-recover state. When it was carefully transported for about 1 minute, the oil-water interface became ambiguous and began to mix with the water layer (Figs. 4d, e). After moving between containers, it became a completely dispersed, uniform solution (Fig. 4f).

[0042] 〔Demulsification (centrifugation)〕 Approximately 175 mL of 6N aqueous citric acid solution was added dropwise to a yellow opaque solution at pH 9.85 (Figure 5a) to obtain a milky white opaque solution at pH 7.00 (Figure 5b). This solution was divided into four equal parts and transferred to centrifuge bottles, and 30 g of refined rice bran oil was poured on top (Figure 5c, d). This was centrifuged (centrifugal acceleration: 3,000 g × 5 minutes) (Figure 5e, f, g), and the demulsified oil and fat were recovered and removed together with the oil and fat layer from above. Although transportation is possible, there is a risk of re-emulsification during container transfer. Therefore, in order to strictly separate the demulsified oil and fat, it is preferable to perform the separation operation without transferring it from the centrifuge bottle container. Note that by removing all of the oil and fat layer, it is possible to remove the demulsified oil and fat without selection.

[0043] One of the bottles subjected to centrifugation was used for measuring the retention time of the demulsified state. Refined rice bran oil was added to the remaining three centrifuge bottles to equalize the weight, and one bottle with the weight equalized with water was prepared and centrifuged again (centrifugal acceleration: 3,000 g × 5 minutes) (Figure 6a, b). There was almost no demulsified product, and only the vacuoles were removed. The centrifugation performed again is preferably performed for confirming the completion of the demulsification operation and for a complete demulsification operation. This was transferred to a separatory funnel (Figure 6c), and the lower aqueous layer was separated (Figure 6d).

[0044] 〔Acid precipitation〕 It was heated in a water bath at 50 °C (Figure 7a), and approximately 155 mL of 6N aqueous citric acid solution was added dropwise to adjust the pH to 5.50 (Figure 7b). The product temperature at this time was about 40 °C, and it was determined that it was suspended when stirring was stopped (Figure 7c).

[0045] 〔Aggregation and recovery〕 Once removed from the water bath, it was placed back in a water bath at 75 °C and heated for 5 minutes to a final product temperature of 58 °C (Figure 8a), and then immediately cooled with running water. After sufficient cooling (Figure 8b), the gelled product was filtered and washed with water (Figure 8c).

[0046] In the above experiment, the demulsified state containing the oil and fat layer did not change after being transported for about 1 minute and maintained the demulsified state in a static state for 48 hours or more (50 hours). However, the hydrophobic colloid of the protein had coagulated (Figs. 9a, b). When this was carefully transferred to another container, the demulsified product maintained the demulsified state although it broke into slightly finer particles and floated near the interface (Figs. 9c, d). If the aqueous layer down to slightly below the interface was recovered, it could be separated. The demulsified product after this container transfer also maintained the state for 4 days (96 hours) after the transfer (Figs. 9e, f). It was confirmed that the demulsified state was maintained for a total of 6 days.

Example

[0047] In this Example 2, the yield of the crude protein gel, its water content, and the solid content oil and fat ratio were confirmed based on the difference in the centrifugal acceleration during the centrifugation in the demulsification step.

[0048] 100.0 g of raw rice bran was added to 666 mL of a 0.200% aqueous sodium hydroxide solution and stirred at room temperature for 1 hour. It was filtered through a sieve with an aperture of 425 μm, the residue was further squeezed, and the extract was recovered. The extract was centrifuged in a centrifuge at a centrifugal acceleration of 2,200×g for 3 minutes to separate the supernatant. 6N aqueous citric acid solution was added dropwise to this supernatant to neutralize it to pH 7.0. Rice oil was added to the neutralized solution and centrifuged at a centrifugal acceleration of 1,000×g or more and 10,000×g or less for 5 minutes twice, and the oil and fat layer was exchanged each time to demulsify the oil and fat, and the aqueous layer with a reduced oil and fat content was recovered. This solution was heated to a product temperature of 40°C, and 6N aqueous citric acid solution was added dropwise to make it pH 5.5. After heating at a product temperature of 60°C for 5 minutes, it was immediately cooled with running water. It was filtered through a filter paper with a retention particle diameter of 5 μm, washed with water, and the corresponding crude protein gel was recovered.

[0049] Then, the yield of the crude protein gel, its water content, and the solid content oil and fat content (the oil and fat content in the crude protein gel) were measured based on the difference in the centrifugal acceleration during the demulsification step. The results are shown in Table 1 below.

[0050]

Table 1

Example

[0051] In this Example 3, experiments were conducted for the purpose of extracting oil and fat by other methods instead of the centrifugation.

[0052] 〔Experimental Example 1 (Liquid-Liquid Separation Treatment)〕 100.0 g of raw rice bran is added to 666 mL of 0.200% sodium hydroxide aqueous solution, and stirred at room temperature for 1 hour. Filter with a sieve having an opening of 425 μm, squeeze the residue further, and collect the extract. The extract is centrifuged at a centrifugal acceleration of 2,200×g for 3 minutes using a centrifuge, and the supernatant is separated. 6N citric acid aqueous solution is added dropwise to the separated supernatant to neutralize it to pH 7.0. The neutralized solution is transferred to a separatory funnel, 50 vol% of n-hexane is added, shaken vigorously, and then allowed to stand, and the aqueous layer is collected. This solution is heated to a product temperature of 40 °C, and 6N citric acid aqueous solution is added dropwise to adjust the pH to 5.5. After heating at a product temperature of 60 °C for 5 minutes, it is immediately cooled with running water. Filter with a filter paper having a retention particle size of 5 μm, wash with water, and collect the corresponding crude protein gel. (The protein was slightly denatured.) As a result, the yield of the crude protein gel was 82.7 g, the moisture content was 73.5%, and the solid content of oil and fat was 66.4%.

[0053] 〔Experimental Example 2 (Ethanol Precipitation)〕 100.0 g of raw rice bran is added to 666 mL of 0.200% sodium hydroxide aqueous solution, and stirred at room temperature for 1 hour. Filter with a sieve having an opening of 425 μm, squeeze the residue further, and collect the extract. The extract is centrifuged at a centrifugal acceleration of 2,200×g for 3 minutes using a centrifuge, and the supernatant is separated. The separated supernatant is heated to a product temperature of 40 °C, and 3N citric acid ethanol solution and 3N citric acid solution (water / ethanol = 1 / 1 vol) are added dropwise to adjust the pH to 5.5. After heating at a product temperature of 60 °C for 5 minutes, it is immediately cooled with running water. Filter with a filter paper having a retention particle size of 5 μm, wash with water, and collect the corresponding crude protein gel. (The protein was denatured.) As a result, the yield of the crude protein gel was 95.4 g, the solvent content rate was 76.1%, and the solid content of oil and fat was 41.2%.

[0054] 〔Experimental Example 3 (n-Hexane Stirring)〕 100.0 g of raw rice bran is added to 666 mL of a 0.200% sodium hydroxide aqueous solution, and the mixture is stirred at room temperature for 1 hour. It is filtered through a sieve with an opening size of 425 μm, the residue is further squeezed, and the extract is collected. The extract is centrifuged in a centrifuge at a centrifugal acceleration of 2,200×g for 3 minutes to separate the supernatant. A 6N citric acid aqueous solution is added dropwise to neutralize the pH to 7.0. 50 vol% of n-hexane is added to the neutralized solution, and the mixture is stirred for 1 hour. The aqueous layer is collected using a separatory funnel. The collected aqueous layer is heated to a product temperature of 40°C, and a 6N citric acid aqueous solution is added dropwise to adjust the pH to 5.5. After heating at a product temperature of 60°C for 5 minutes, it is immediately cooled with running water. It is filtered through a filter paper with a retention particle size of 5 μm, washed with water, and the corresponding crude protein gel is collected. (The protein was denatured.) As a result, the yield of the crude protein gel was 121.7 g, the moisture content was 87.8%, and the solid content oil content was 57.5%.

[0055] 〔Experimental Example 4 (Demulsification of Crude Rice Bran Oil)〕 100.0 g of raw rice bran is added to 666 mL of a 0.200% sodium hydroxide aqueous solution, and the mixture is stirred at room temperature for 1 hour. It is filtered through a sieve with an opening size of 425 μm, the residue is further squeezed, and the extract is collected. The extract is centrifuged in a centrifuge at a centrifugal acceleration of 2,200×g for 3 minutes to separate the supernatant. A 6N citric acid aqueous solution is added dropwise to neutralize the pH to 7.0. Crude rice bran extract oil is added to the neutralized solution, and the operation of centrifuging at a centrifugal acceleration of 3,000×g for 5 minutes is performed twice, and the oil layer is replaced each time to demulsify the oil. The aqueous layer with a reduced oil content is collected (the gum content in the crude oil swells, making it difficult to separate the demulsified product from the crude oil. Also, the color is dark, making it difficult to distinguish the demulsified product in the crude oil). This solution is heated to a product temperature of 40°C, and a 6N citric acid aqueous solution is added dropwise to adjust the pH to 5.5. After heating at a product temperature of 60°C for 5 minutes, it is immediately cooled with running water. It is filtered through a filter paper with a retention particle size of 5 μm, washed with water, and the corresponding crude protein gel is collected. As a result, the yield of the crude protein gel was 65.5 g, the moisture content was 79.8%, and the solid content oil content was 44.8%.

[0056] 〔Experimental Example 5 (Demulsification of Rapeseed Oil)〕 Add 100.0 g of raw rice bran to 666 mL of a 0.200% sodium hydroxide aqueous solution, and stir at room temperature for 1 hour. Filter through a sieve with an opening of 425 μm, squeeze the residue further, and collect the extract. Centrifuge the extract in a centrifuge at a centrifugal acceleration of 2,200×g for 3 minutes to separate the supernatant. Neutralize to pH 7.0 by dropping 6N citric acid aqueous solution. Add rapeseed oil to the neutralized solution and centrifuge at a centrifugal acceleration of 3,000×g for 5 minutes twice, and demulsify the oil and fat by replacing the oil and fat layer each time, and collect the aqueous layer with a reduced oil and fat content. Heat this solution to a product temperature of 40 °C, and drop 6N citric acid aqueous solution to make the pH 5.5. After heating at a product temperature of 60 °C for 5 minutes, immediately cool with running water. Filter through a filter paper with a retention particle size of 5 μm, wash with water, and collect the corresponding crude protein gel. As a result, the yield of the crude protein gel was 74.2 g, the water content was 81.0%, and the solid content oil and fat content was 44.4%.

[0057] 〔Experimental Example 6 (Activated Carbon Adsorption)〕 Crush granular activated carbon in a mortar, heat-activate the powder that passed through a sieve with an opening of 53 μm at 120 °C for 3 hours, and then let it cool in a desiccator. This was used as the activated carbon for the following experiments. Add 100.0 g of raw rice bran to 666 mL of a 0.200% sodium hydroxide aqueous solution, and stir at room temperature for 1 hour. Filter through a sieve with an opening of 425 μm, squeeze the residue further, and collect the extract. Centrifuge the extract in a centrifuge at a centrifugal acceleration of 2,200×g for 3 minutes to separate the supernatant. Neutralize to pH 7.0 by dropping 6N citric acid aqueous solution. Add 13.4 g of activated carbon (average amount of oil and fat in the solution) to the neutralized solution and stir for 18 hours. When this solution was centrifuged at a centrifugal acceleration of 3,000×g for 3 minutes, most of the activated carbon and protein precipitated in an adsorbed state. The gray supernatant was collected. Since the solution coagulated within 1 hour, it was heated to a product temperature of 40 °C, and 6N citric acid aqueous solution was dropped to make the pH 5.5. After heating at a product temperature of 60 °C for 5 minutes, immediately cool with running water. Filter through a filter paper with a retention particle size of 5 μm, wash with water, and collect the corresponding crude protein gel. As a result, the yield of the crude protein gel was 13.0 g, the water content was 74.3%, and the reference value of the solid content oil and fat content was 46.3%.

[0058] [Experimental Example 7 (Cooling and Standing Still)] 100.0 g of raw rice bran was added to 666 mL of a 0.200% sodium hydroxide aqueous solution and stirred at room temperature for 1 hour. It was filtered through a sieve with an opening size of 425 μm, the residue was further squeezed, and the extract was collected. 6N citric acid aqueous solution was added dropwise to neutralize to pH 7.0. Two samples of this specimen were prepared and allowed to stand at 0 °C. The specimens after cooling and standing still were taken out after 22.5 hours and 45 hours, and centrifuged at a centrifugal acceleration of 3,000×g for 3 minutes while still cold, and the supernatant was separated (oil and fat had aggregated on the liquid surface immediately after taking out, but dispersed immediately during the operation). This solution was heated to a product temperature of 40 °C, and 6N citric acid aqueous solution was added dropwise to adjust the pH to 5.5. After heating at a product temperature of 60 °C for 5 minutes, it was immediately cooled with running water. It was filtered through a filter paper with a retention particle size of 5 μm, washed with water, and the corresponding crude protein gel was recovered. As a result, the one cooled for 22.5 hours had a crude protein gel yield of 79.0 g, a water content of 73.2%, and a solid content of oil and fat of 64.9%. The one cooled for 45 hours had a crude protein gel yield of 85.3 g, a water content of 75.3%, and a solid content of oil and fat of 63.3%.

[0059] [Experimental Example 8 (Demulsification without Oil Layer)] 100.0 g of raw rice bran was added to 666 mL of a 0.200% sodium hydroxide aqueous solution and stirred at room temperature for 1 hour. It was filtered through a sieve with an opening size of 425 μm, the residue was further squeezed, and the extract was collected. The extract was centrifuged at a centrifugal acceleration of 2,200×g for 3 minutes using a centrifuge, and the supernatant was separated. 6N citric acid aqueous solution was added dropwise to neutralize to pH 7.0. Purified water was added to the neutralized solution in the same amount as the oil layer in the example and centrifuged at a centrifugal acceleration of 3,000×g for 5 minutes, and the demulsified oil and fat floating on the liquid surface was sucked and recovered as much as possible with a pipette (at this time, it was difficult to recover the demulsified oil and fat, and the extract itself was also sucked, resulting in a sucked liquid volume of 76.4 g and a remaining extract of 808.8 g, and a sucked volume of 8.6% of the total amount). The remaining extract was heated to a product temperature of 40 °C, and 6N citric acid aqueous solution was added dropwise to adjust the pH to 5.5. After heating at a product temperature of 60 °C for 5 minutes, it was immediately cooled with running water. It was filtered through a filter paper with a retention particle size of 5 μm, washed with water, and the corresponding crude protein gel was recovered. As a result, the crude protein gel yield was 69.2 g, the moisture content was 78.0%, and the solid content oil and fat content was 55.2%.

[0060] 〔Considerations on Experimental Examples 1 to 8〕 In Experimental Examples 1 to 3, along with the contact with the organic solvent, the protein was denatured, and the solid content oil and fat content was higher than that of the demulsification operation. In Experimental Example 4, due to the influence of the color density of the extracted crude oil and the gum content contained, it is difficult to judge the demulsification state, and there is concern that the demulsification efficiency will decrease. Therefore, degummed oil or clarified oil is desirable. In Experimental Example 5, it was found that the demulsification process can also be carried out in other vegetable oils. In Experimental Example 6, since activated carbon is not suitable as an oil selective adsorbent, it is necessary to select other adsorbents. In Experimental Example 7, although oil separation occurs once by cooling, it is an unstable separation state that disperses during the operation, and it is difficult to demulsify and separate only by cooling. In Experimental Example 8, although demulsified oil is generated on the liquid surface, it is difficult to separate from the extract. Also, compared with the same centrifugal acceleration in the examples, the demulsified oil was less. Therefore, the result was a high solid content oil and fat content.

Example

[0061] In this Example 4, vegetable protein was produced using soybeans as the raw material food.

[0062] 〔Experimental Example 9〕 Commercially available dried soybeans produced from spinach were pulverized with a mixer and passed through an 18-mesh (aperture 1 mm) sieve. This was designated as pulverized soybeans. 100.0 g of the pulverized soybeans was added to 666 mL of a 0.200% aqueous sodium hydroxide solution and stirred at room temperature for 1 hour. It was filtered through a sieve with an aperture of 425 μm, the residue was further squeezed, and the extract was collected. The extract was centrifuged at a centrifugal acceleration of 2,200×g for 3 minutes using a centrifuge, and the supernatant was separated. A 6N aqueous citric acid solution was added dropwise to neutralize to pH 7.0. Corn oil was added to the neutralized solution and centrifuged at a centrifugal acceleration of 3,000×g for 5 minutes twice, and the oil layer was replaced each time to demulsify the oil and fat, and the aqueous layer with a reduced oil and fat content was collected. This solution was heated to a product temperature of 40°C, and a 6N aqueous citric acid solution and an 18N aqueous citric acid solution were added dropwise to adjust the pH to 4.2. After heating at a product temperature of 60°C for 5 minutes, it was immediately cooled with running water. It was filtered through a filter paper with a retention particle size of 5 μm, washed with water, and the corresponding crude protein gel was recovered. As described above, as a result of carrying out the demulsification step at a centrifugal acceleration of 3,000×g, the yield of the crude protein gel was 136.7 g, the moisture content was 73.4%, and the solid content oil and fat content was 12.6%.

[0063] [Experimental Example 10] Commercially available dried soybeans produced from spinach were pulverized with a mixer and passed through an 18-mesh (aperture 1 mm) sieve. This was designated as pulverized soybeans. 100.0 g of the pulverized soybeans was added to 666 mL of a 0.200% aqueous sodium hydroxide solution and stirred at room temperature for 1 hour. It was filtered through a sieve with an aperture of 425 μm, the residue was further squeezed, and the extract was collected. The extract was centrifuged at a centrifugal acceleration of 2,200×g for 3 minutes using a centrifuge, and the supernatant was separated. This solution was heated to a product temperature of 40°C, and a 6N aqueous citric acid solution and an 18N aqueous citric acid solution were added dropwise to adjust the pH to 4.2. After heating at a product temperature of 60°C for 5 minutes, it was immediately cooled with running water. It was filtered through a filter paper with a retention particle size of 5 μm, washed with water, and the corresponding crude protein gel was recovered. As a result of not performing the demulsification step as described above, the yield of the crude protein gel was 132.3 g, the moisture content was 76.2%, and the solid content oil and fat content was 27.9%.

Industrial Applicability

[0064] The demulsification method by centrifugation of the present invention and the method for separating vegetable proteins using the same can be used for the purpose of separating and recovering vegetable proteins from foods containing vegetable proteins or vegetable proteins and fats and oils. Further, the demulsification method by centrifugation of the present invention is not limited to the separation and recovery of vegetable proteins and can also be used as a demulsification method in various fields.

Claims

1. A demulsification method for separating oil and fat components from an emulsified component containing at least vegetable protein, characterized in that vegetable oil is added to the emulsified component and then centrifugation is performed, the demulsification method by centrifugation.

2. A method for separating vegetable protein for separating and recovering vegetable protein from a food containing vegetable protein, an alkali extraction step of stirring the raw material food in an aqueous alkali solution, a solid-liquid separation step of separating the mixed solution after the alkali extraction step into a solid component and an emulsified component, a demulsification step of demulsifying the emulsified component separated in the solid-liquid separation step by centrifugation, an acid precipitation step of lowering the pH of the emulsified component after the demulsification step to generate a crude protein gel, comprising a crude protein gel recovery step of recovering the crude protein gel generated in the acid precipitation step, wherein the demulsification step is performed by the demulsification method according to Claim 1, the method for separating vegetable protein.

3. The method for separating vegetable protein according to Claim 2, wherein the food is rice bran or soybeans, and the demulsification step is performed at a centrifugal acceleration of 1,000 g or more.

4. A method for adjusting the oil and fat content of vegetable protein separated and recovered from a food containing vegetable protein, manufactured by the method for separating vegetable protein according to Claim 2 or 3, characterized in that the oil and fat content in the vegetable protein separated and recovered by the centrifugal acceleration of centrifugation in the demulsification step is adjusted, the method for adjusting the oil and fat content of vegetable protein.

5. Vegetable protein formed using rice bran or soybeans, wherein the oil and fat content is 32 wt% or more and 50 wt% or less in the vegetable protein formed using rice bran, and 13 wt% or more and 28 wt% or less in the vegetable protein formed using soybeans, and is low in denaturation, and the protein content when the oil and fat is removed is 65 wt% or more and 85 wt% or less, the vegetable protein.

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