JP2618540B2 - Protein complex - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel protein complex and its use.

[0002]

2. Description of the Related Art Proteins such as gelatin, albumin, and casein have an emulsifying action and have been conventionally used as food or pharmaceutical emulsifiers.

[0003]

However, these protein emulsifiers are generally not always satisfactory in terms of emulsifying power. Therefore, if a protein-based emulsifier having a further enhanced emulsifying power as compared to the conventional protein emulsifier as described above is developed, the use of the protein emulsifier will be further expanded. . The present invention
It is an object of the present invention to provide a novel protein-based substance that can meet such a demand, and to provide a novel emulsifier comprising the substance.

[0004]

Means for Solving the Problems The present inventors have conducted various studies in an attempt to achieve the above object, and have completed the present invention. That is, the present invention provides a protein complex formed by binding a lysophospholipid and a protein. The present invention also provides an emulsifier comprising the above protein complex.

Hereinafter, the present invention will be described in detail. In the present invention, lysophospholipid is one of glycerol of phospholipid.
One molecule of the fatty acid bound to the 2- or 2-position is removed. Specifically, lysolecithin (lysophosphatidylcholine), lysophosphatidylethanolamine, lysophosphatidylserine, lysophosphatidylglycerol, lysophosphatidylinositol, lysophosphatidic acid And the like.

[0006] The protein in the present invention has an emulsifying effect and includes all proteins conventionally used as emulsifiers. For example, albumin such as ovalbumin and lactalbumin, casein, soybean protein, gelatin and the like can be mentioned. Further, these proteins may be partially denatured by some means. The present inventors have recognized that some partially denatured proteins are more easily bound to lysophospholipids than their undenatured proteins.

[0007] The protein complex of the present invention is obtained by binding a lysophospholipid as described above to a protein. As used herein, the term “bonding” means that the degree of bonding between the two is in a bonding state such as to exhibit the following behaviors (a) and (b). (A) When a protein precipitant (for example, a 4 to 6% trichloroacetic acid solution) is added after mixing and stirring the respective aqueous solutions, lysophospholipids are found to precipitate together with the protein. (B) When the respective aqueous solutions were mixed and stirred, and gel filtration was performed, elution of another fraction was observed before elution of free protein. When this was subjected to electrophoresis using polyacrylamide, separation was observed. Since the protein does not proceed to the gel region and remains in the concentrated gel region, the molecular weight of the protein is usually about 10,000 to 1
While this is about 100,000, this is about several hundred thousand to one
It is estimated to be around one million.

[0008] The binding ratio between lysophospholipid and protein in the protein complex of the present invention varies somewhat depending on the type of protein, but generally about 20 to 60 mol of lysophospholipid per 1 mol of protein. If the ratio of the lysophospholipid is too small, the effect of improving the emulsifying power of the protein is unlikely to be expected. In addition, it has been observed that lysophospholipids do not actually bind to proteins so much as to exceed the above upper limit, and in fact, the excess amount of lysophospholipids remains in a mixed state in a solution during the production process. Typical specific examples of the binding ratio in the protein complex product according to the type of protein are shown below. Kind of protein Protein to lysophospholipid (molar ratio) ovalbumin 1:24 lactalbumin 1:36 casein 1:60 soybean protein 1:22 partially denatured ovalbumin 1:36 (heat denatured at 80 ° C. for several minutes)

[0009] The protein complex of the present invention may be in the form of an aqueous solution obtained in the course of its production. However, from the viewpoint of handling as a product or storage, it is usually used, for example, freeze drying, spray drying and the like. It is generally in the form of a dried product dried by means. Such a protein complex of the present invention may contain other components and raw materials (eg, unbound lysophospholipid other saccharides, synthetic emulsifiers) besides the conjugate of lysophospholipid and protein, as long as the object of the present invention is not impaired. (Eg, fatty acid monoglycerides).

Next, a typical method for producing the protein complex of the present invention will be described. First, an aqueous solution of lysophospholipid is prepared. At this time, the concentration of the lysophospholipid is generally about 1 to 200 mM. If the concentration is too low, it is difficult to bind to the protein. On the other hand, if the concentration is too high, the lysophospholipid comes to float on the surface of water, which makes mixing and dispersion difficult. In order to improve the dissolution / dispersion of the lysophospholipid, the above solution is, for example, an ultrasonic homogenizer (1).
(500 to 500 W), etc., for about 1 to 5 minutes. Next, an aqueous solution of the protein is separately prepared. At this time, the protein concentration is generally about 0.1 to 5 mM. When preparing the above both aqueous solutions, it is advisable to prepare them appropriately according to the desired binding ratio between the lysophospholipid and the protein in the final product.
From the viewpoint of the binding efficiency between the lysophospholipid and the protein, it is preferable to use both solutions in equal volumes.

The lysophospholipid aqueous solution thus prepared and the protein aqueous solution are then mixed and stirred. It is preferable that the pH of the lysophospholipid solution is adjusted before mixing, or the pH of the mixed solution after mixing is usually adjusted to about 2 to 5. It has been found that when the pH is lower than the isoelectric point of the protein, and more preferably about one lower than the pH of the isoelectric point, the protein in a mixed state and the lysophospholipid are easily bonded. Hydrochloric acid, phosphoric acid or the like is preferably used for pH adjustment. Stirring of both solutions is preferably carried out vigorously in order to promote the binding between the lysophospholipid and the protein by sufficient dispersion. Such stirring may be performed by performing ultrasonic treatment at 20 to 60 ° C. for about 2 to 30 minutes using an apparatus such as an ultrasonic homogenizer (100 to 500 W).

As a result of such a stirring treatment, a protein complex in which the lysophospholipid and the protein are bound is formed. The protein complex of the present invention may be in the form of the aqueous solution obtained as it is, but is usually dried by means of freeze-drying, spray-drying or the like from the viewpoint of handling as a product or storage. To process.

If it is desired to remove an excessive amount of lysophospholipid which remains in a mixed state in the solution without participating in the binding in the above-mentioned production process, the solution after the stirring treatment is subjected to, for example, (B) ultracentrifugation to precipitate the protein complex portion and remove the lysophospholipid remaining in the liquid portion, or
(B) ultrafiltration to separate and remove from the protein complex portion, or alternatively,
(C) A protein precipitant (for example, a 4 to 6% trichloroacetic acid solution) may be added to precipitate the protein complex, and the lysophospholipid remaining in the liquid may be removed.

The thus obtained protein complex of the present invention comprises:
As is clear from the results of the test examples described below, the compound has an excellent emulsifying action and is much higher in emulsifying power than conventional protein emulsifiers. When the protein complex of the present invention is used as an emulsifier, the protein complex is converted to a solid content of 0.5%.
An aqueous solution having a concentration of about 10% to 10% may be prepared, and then emulsified by, for example, adding a predetermined fat or oil. In this case, the emulsification may be carried out by using a conventionally used stirring device under the condition of, for example, several thousand to several tens of thousands of rpm for 2 to 15 minutes according to a conventional method. In order to reduce the size of oil particles, an ultrasonic homogenizer may be used.

[0015]

The protein complex of the present invention has a much higher emulsifying power than the conventional protein emulsifier, as is clear from the results of the test examples described below. It is thought that this is because the oil emulsifier is more stable than that surrounded by the protein emulsifier and makes the oil particles hard to move.

[0016]

Examples and Test Examples Hereinafter, the present invention will be described in more detail with reference to Examples and Test Examples. In the present invention,% means% by weight. Example 1 (1) A 30 mM aqueous solution of egg yolk lysolecithin (98% purity) and a 1 mM aqueous solution of ovalbumin were prepared, and both were mixed in equal volumes. The pH of the mixed solution was adjusted to pH 3 using hydrochloric acid, and then ultrasonically treated at 25 ° C. for 5 minutes using an ultrasonic homogenizer (500 W).
This treated liquid was then freeze-dried to produce the protein complex of the present invention.

(2) A part of the treated solution before drying was fractionated, a 4% trichloroacetic acid solution was added thereto, the resulting precipitate was separated by filtration, and the yolk lysolecithin in the precipitate and the residual in the filtrate were removed. As a result of examining the ratio of yolk lysolecithin to the former, lysolecithin in the former was 24/30 of the lysolecithin used and the ratio in the latter was 6/30. 24/30, ie
It was presumed that 24 mol of yolk lysolecithin was bound to 1 mol of ovalbumin.

(3) On the other hand, a part of the treatment solution before drying was fractionated and subjected to gel filtration (filler: Sephacryl S-200HR manufactured by Pharmacia). No elution of unbound ovalbumin was observed. This indicated that ovalbumin was all converted to another form of higher molecular weight than itself. When the solute portion of the eluted polymer was subjected to electrophoresis using polyacrylamide, it was found that the product did not proceed to the separation gel region but remained in the concentrated gel region. As a result of the above (2) and (3), the binding ratio (molar ratio) between ovalbumin and egg yolk lysolecithin in the obtained protein complex was found to be about 24 for the former and 1 for the latter.

Example 2 (1) A 66 mM aqueous solution of egg yolk lysolecithin (purity 98%) and a 1 mM aqueous solution of casein were respectively prepared, and both were mixed in equal volumes. After adjusting the pH of this mixed solution to pH 3 using hydrochloric acid, an ultrasonic homogenizer (500
W) was used for sonication at 25 ° C. for 5 minutes. This treated liquid was then freeze-dried to produce the protein complex of the present invention.

(2) A part of the treated solution before drying was fractionated, a 4% trichloroacetic acid solution was added thereto, the resulting precipitate was separated by filtration, and the yolk lysolecithin in the precipitate and the residual in the filtrate were removed. As a result of examining the ratio of yolk lysolecithin, the former lysolecithin was 60/66 of the lysolecithin used, and the ratio of the latter was 6/66, indicating that the conversion ratio of yolk lysolecithin to the protein complex was about 60/66, ie
It was presumed that 60 mol of egg yolk lysolecithin was bound to 1 mol of casein.

(3) On the other hand, a part of the treatment liquid before drying was fractionated and subjected to gel filtration (filler: Sephacryl S-200HR manufactured by Pharmacia). No elution of unbound casein was observed. This indicated that casein was all converted to another form of macromolecule rather than itself.
When the solute portion of the eluted polymer was subjected to electrophoresis using polyacrylamide, it was found that the product did not proceed to the separation gel region but remained in the concentrated gel region. As a result of the above (2) and (3), it was found that the binding ratio (molar ratio) of casein to yolk lysolecithin in the obtained protein complex was about 60 for the former 1 and about 60 for the latter.

Test Example 5% (in terms of solid content) aqueous solution of the protein complex of the present invention obtained in Examples 1 and 2 above (adjusted to pH 3 with hydrochloric acid)
Was prepared respectively. To 100 g of each of these solutions, 15 g of soybean salad oil was added, and 12,000
The mixture was emulsified by stirring at 0 rpm for 5 minutes. Each of the thus obtained emulsions was then subjected to an emulsifying power test (measurement of aqueous phase separation after 48 hours and particle size measurement of emulsified fats and oils (4 ° C.)).

As a control, ovalbumin, casein and egg yolk lysolecithin were used alone in place of the protein complex of the present invention, respectively, and a 5% aqueous solution was prepared. It was subjected to the same emulsification test.

The results are shown in the table below. Table This onset separation percentage of light products versus irradiation article yolk Rizoreshichi yolk Rizoreshi albumen A cold yolk lyso on / egg white Arve Chin / casei Rubumi Item Min complex down complex down in lecithin 48 hours after the aqueous phase (%) 0 5.0 26.0 15.6 12.0 Average particle size of emulsified oil and fat (μ) Immediately after emulsification 0.60 1.42 5.80 2.77 2.60 After 48 hours 0.67 2.10> 20 4.20 2.60 Total evaluation of emulsifying power ○ ○ × △ △ Notes: 1. The symbols in the table have the following significance. ○: Excellent emulsifying power △: Some emulsifying power is recognized ×: Poor emulsifying power The particle size was measured by a laser light dynamic scattering method.

From the results in the above table, it is understood that the protein complex of the present invention has a much higher emulsifying power than the conventional protein emulsifier, and that the particle size of the emulsified fat is considerably smaller.

[0026]

According to the present invention, a novel protein complex having an emulsifying power much higher than that of a conventional protein emulsifier is provided. Therefore, when this protein complex is used as an emulsifier, further expansion of the use of the protein emulsifier in the fields of food and medicine can be expected.

Claims (2)

(57) [Claims] 1. A protein complex comprising a lysophospholipid and a protein bound thereto. 2. An emulsifier comprising the protein complex of claim 1.