JPH05222097A - Preparation of zein with low pigment content and little odor - Google Patents

Abstract

PURPOSE:To provide zein of little odor and pale color tone, markedly reduced in its yellowness compared to conventional zein. CONSTITUTION:In a method for obtaining the subject zein from a colored solution of zein with hydrous ethanol as the solvent, such a colored solution is cooled to deposit the zein dissolved in the solution; this zein is then separated and collected, thus obtaining the objective zein.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for preparing zein having a low pigment content and a low odor, and in particular, a method for collecting a light-colored zein having a low pigment content and a low odor when producing zein from corn or corn gluten meal. It is about.

[0002]

BACKGROUND ART Zein (also called zein) is a main protein of corn and is a substance that belongs to the prolamin system and is soluble in hydrous alcohol. This substance can be easily formed into a film or fiber, is tough, and has excellent heat resistance, acid resistance, water resistance, and electrical insulation. It is used for surface coating of products, adhesives for plywood, moisture-proofing agents, moisture-proofing coatings for electric parts, and coating agents for foods and tablets.

In order to obtain such useful zein, corn or corn gluten meal obtained from corn is usually used as a starting material.
Extraction is performed by using a lower alcohol such as hydrous ethanol having a concentration of up to 95% (weight basis, the same applies below) or isopropanol of about 90% as a solvent, and then distilling off the solvent or converting the extract to cold water A method of recovering zein solids by using means such as charging has been adopted. Further, JP-A-61-16770 discloses a method of increasing the yield of zein by dropping such an extract into a neutral salt solution instead of adding it to cold water. Further, JP-A-63-185998 discloses a method of adding ethanol to the extract to adjust the ethanol concentration to remove precipitated impurities, and further JP-A-63-1.
No. 85999 discloses a method for obtaining zein having a large ethanol solubility by adjusting the pH of the extract.

By the way, in such a conventional method,
The odor and color components derived from the raw corn, when extracted with hydrous ethanol, is extracted together with zein, and is to be separated and recovered together with zein,
The product obtained has a characteristic odor and is fairly yellowish. This limits the field of application of zein as a coating agent as described above, and in many food fields where light-colored, rather colorless, and odorless materials are desired, conventional zein is extremely It did not meet that demand. The pigment contained in corn is known to have many ethanol-soluble xanthophylls among carotenoids. Since it is more oil-soluble, when water is added to a hydrous ethanol solution as in the conventional method, a yellow pigment is also deposited along with zein, and it is extremely difficult to separate the two.

[0005]

The present invention has been made in view of such circumstances, and its object is to reduce the yellow tint of zein as compared with the conventional zein, which has a light color tone. Moreover, it is to provide a method for obtaining zein having less odor.

[0006]

In order to solve such a problem, the present invention provides a method for extracting zein having a low dye content and a low odor from a colored solution of zein using water-containing ethanol as a solvent. By cooling the coloring solution, the zein dissolved in the coloring solution is precipitated,
The gist is a method for preparing zein having a small dye content and a small odor, which is characterized by separating and collecting the precipitated zein from the precipitation liquid.

[0007]

That is, the present invention utilizes the fact that the solubility of zein in water-containing ethanol remarkably depends on temperature.
By cooling a hydrous ethanol colored solution of zein below the temperature of the solubility curve, zein is precipitated. And, at that time, since the dye component present in the coloring solution of zein is more oil-soluble than zein, it is dissolved in ethanol as it is, is left as it is, and is prevented from precipitating with zein, resulting in a color tone. It is now possible to obtain the pale zein.

In addition, the zein thus obtained by precipitation is surprisingly less odorous than the conventional zein, and therefore zein close to odorless can be obtained. The hydrous ethanol solution after separating the precipitated zein has an advantage that it can be used again for the extraction of zein.

[0009]

[Specific configuration] By the way, in the present invention, a coloring solution of zein using hydrous ethanol as a solvent, which is used for obtaining zein with less odor and coloration, means that zein is dissolved in hydrous ethanol as a solvent to produce a coloring In the present invention, a solution obtained by extracting and separating zein from corn gluten meal using hydrous ethanol, a hydrous ethanol solution of crude zein having a large pigment content, etc. Or, if necessary after being concentrated, it will be used.

In particular, in the present invention, the former solution, that is, a colored solution obtained by extracting and separating zein from corn gluten meal by using hydrous ethanol, and the ethanol-extracted colored liquid as it is or if necessary, is concentrated. , Advantageously used. The starting material, corn gluten meal, is obtained as a by-product in the process of separating and producing corn starch from corn by an ordinary wet treatment method. Then, when zein was extracted from the gluten meal with hydrous ethanol, 6 fold of zein was added to corn gluten meal according to a conventional method.
Hydrous ethanol with an ethanol concentration of 0-95%
It is carried out by adding 3 to 10 times the amount of the raw material and extracting at a temperature of about 40 to 60 ° C. for 0.5 to 2 hours. In addition, if necessary, during such extraction,
The pH can be adjusted by a known method, and the colored solution obtained by extraction is subjected to an operation such as centrifugation or filtration to separate insoluble residues. Also,
A coloring solution of zein such as such an extraction coloring solution is subjected to a concentration operation, if necessary, so that its solid content concentration is 20 to
The operation according to the present invention is applied with a solution of about 50%.

In the present invention, a colored solution of zein such as the extracted colored solution as described above is cooled to a temperature not higher than the temperature indicated by the melting temperature curve to precipitate zein. The specific temperature setting at that time is determined by the water content of the zein coloring solution. That is, FIG. 1 shows that for various water contents of water-containing ethanol,
After heating and dissolving zein at various ratios, the temperature of the solution was lowered, and the temperature at which the solution became cloudy due to the appearance of precipitates was examined. As is clear from FIG. The solubility of is significantly affected by the amount of water and the temperature in the solvent, hydrous ethanol. As a result of investigations by the present inventors, the precipitation temperature of zein (y: ° C.) was found to be
A quadratic function such as:

Y = a (x-b) ² + c

And their coefficients a,
b and c are well correlated in a linear equation with respect to the logarithm of the zein concentration (z:%) at that time, and as a result, the zein precipitation temperature: y becomes the following approximate equation:

[0014]

[Equation 1]

It has become clear that it can be represented by

Therefore, in the present invention, in order to precipitate the zein by cooling the colored solution of zein, it is necessary to cool the colored solution of zein to the precipitation temperature of zein according to the approximate expression: y or less. There, the pigment component eluted with zein in the extraction process, etc.
Dissolved as a solute in hydrous ethanol as a solvent,
As a result, zein will be deposited and separated with almost no such dye component.

The zein thus precipitated is separated and recovered from the precipitation solution by a known appropriate means such as centrifugation or filtration, and then the solvent (alcohol) is completely removed by drying. However, the precipitate is likely to be a gel-like aggregate near room temperature, and this tendency is remarkable especially when the water content in ethanol is large.When separating the precipitated zein by filtration, the above-mentioned approximate formula is used. Precipitation temperature: a temperature lower than the value of y by 10 ° C. or more,
It is desirable to set the cooling temperature condition.

The zein thus obtained has a light color tone with little coloration, has a very low odor, and is almost odorless, and when dissolved in hydrous ethanol, it is completely dissolved and extremely thin. It gives a yellow, clear and transparent solution.

In the present invention, in order to carry out more complete purification (decolorization) of zein, the method of the present invention can be repeatedly carried out. For example, zein recovered as described above can be used in an appropriate amount of hydrous alcohol. It is possible to dissolve zein, concentrate it if necessary, and then cool it again to precipitate zein, thereby further decolorizing zein.

[0020]

EXAMPLES Some examples of the present invention will be shown below to clarify the present invention in more detail. However, the present invention is not limited by the description of such examples. It goes without saying that you do not receive it.
Further, in the present invention, in addition to the following examples, further, in addition to the above specific description, various changes and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention, It should be understood that improvements and the like can be added. In addition, all percentages in the following examples are shown by weight unless otherwise specified.

Example 1 The extraction operation for 50 g of corn gluten meal was carried out by 90
After using 300 ml of% hydrous ethanol at 60 ° C. for 2 hours, solid-liquid separation was performed using a centrifuge to obtain a yellow-colored zein extraction solution. Then, the extracted solution was cooled to -10 ° C and left at that temperature for 16 hours to precipitate zein. Thereafter, the precipitate was separated by filtration while keeping the temperature low, washed with a small amount of cold ethanol, and then vacuum dried to obtain 8.9 g of colorless and odorless purified zein.

On the other hand, for comparison, the yellow zein extraction solution extracted in the same manner as above was concentrated to a nonvolatile content of 25% and then added dropwise to 500 ml of cold water (1-2 ° C.) to give zein. Was precipitated, filtered, separated, and dried in vacuum to obtain 9.3 g of yellowish zein having a unique odor.

In order to quantitatively express the degree of purification of the two types of zein obtained as described above, each sample was dissolved in 74% hydrated ethanol to prepare a hydrated ethanol solution containing zein: 2%. After preparation, the difference in absorbance (ΔA) at 400 nm and 500 nm was measured. As a result, the ΔA of the purified zein obtained according to the method of the present invention was 0.082, whereas the ΔA of the zein of Comparative Example was 0.495.
It was also numerically confirmed that the yellow component was significantly reduced by the method of the present invention.

Example 2 50 g of corn gluten meal was extracted with 300 ml of 80% water-containing ethanol at 60 ° C. for 2 hours, and then solid-liquid separation was performed using a centrifuge to give a yellow color. A colored zein extraction solution was obtained. Then, the extracted solution was cooled to -20 ° C and left at that temperature for 16 hours to precipitate zein. Thereafter, the obtained precipitate was separated by filtration while keeping the temperature low, washed with a small amount of cold ethanol, and then dried in vacuum to obtain 9.5 g of colorless and odorless purified zein. And
Similarly to Example 1, the absorbance difference ΔA of the obtained zein was obtained.
Was measured and a value of 0.084 was obtained.

Example 3 50 g of corn gluten meal was extracted with 300 ml of 75% hydrous ethanol at 60 ° C. for 2 hours, and then a yellow zein extraction solution was separated using a centrifuge. .. Next, this extraction solution was cooled to -20 ° C and left at that temperature for 16 hours to extract zein. Thereafter, the precipitate was separated by filtration while keeping the temperature low, washed with a small amount of cold ethanol, and then vacuum dried to obtain 9.8 g of colorless and odorless purified zein. Then, in the same manner as in the example, when the absorbance difference: ΔA of the obtained zein was measured, it was 0.088.
Met.

Example 4 50 g of corn gluten meal was extracted with 300 ml of 80% water-containing ethanol at 60 ° C. for 2 hours and then centrifuged to separate a yellow zein extraction solution. Then, the extracted solution is concentrated to obtain non-volatile components:
27 g of a concentrate having a content of 40.0% and a water content of 17.6% was obtained.
Then, to this concentrated liquid, 200 ml of 99.5% ethanol at -15 ° C was added and stirred, and then cooled to -10 ° C to precipitate zein. After standing overnight, the formed precipitate was separated by filtration at a low temperature, washed with a small amount of cold ethanol, and then dried under vacuum to obtain 9.2 g of colorless and odorless purified zein. When the difference in absorbance: ΔA was measured in the same manner as in Example 1, it was 0.083.

Example 5 Using the yellowish zein prepared as a comparative sample in Example 1, 8 g thereof was redissolved in 160 ml of 93% hydrous ethanol. Then, the zein solution thus obtained was cooled to −10 ° C. and left at that temperature for 16 hours to precipitate zein. afterwards,
The generated precipitate is separated by filtration while maintaining a low temperature,
After washing with a small amount of cold ethanol, vacuum drying was performed to obtain 7.3 g of colorless and odorless purified zein. In addition, Example 1
When the difference in absorbance: ΔA was measured in the same manner as above,
It was 083.

[0028]

As is apparent from the above description, according to the present invention, it is possible to economically produce zein, which is extremely colored and is suitable for coating on medicines and foods.
Moreover, since the zein obtained according to the present invention has a light color, it can be used in various food fields and other industrial fields, which have been difficult to use conventionally. Moreover, in this way, in addition to the effect of remarkably reducing the coloring, the unique odor can be remarkably reduced as compared with the conventional ones, so that it can be advantageously used in the food field, particularly chocolate coating and the like. Of.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the temperature at which zein is precipitated from a hydrous ethanol solution of zein and the water concentration in a hydrous ethanol solvent.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location C07K 3/24 7731-4H C08H 1/00 NVD 8215-4J

Claims (1)

[Claims] 1. A method for extracting zein having a low dye content and a low odor from a colored solution of zein using water-containing ethanol as a solvent, and cooling the colored solution of zein to dissolve it in the colored solution. A method for preparing zein having less pigment content and odor, which comprises precipitating zein to be precipitated, and separating and collecting the precipitated zein from the precipitation solution.