JPH0125783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extracting and purifying mylopigments from mylopigment-containing substances.

The pigment of Milo (grain sorghum) is present in the exocarp, seed coat, and rod surrounding the grain, and is particularly abundant in the exocarp. Milo pigments are mainly composed of flavone pigments and are known to contain apigenin, quercimeritrin, and the like. Mylo dyes exhibit excellent durability against light and heat, are more stable than other natural dyes, and have good dyeability. Such mylo pigments are usually commercially available in the form of a pigment solution dissolved in weakly alkaline propylene glycol/water, and are used in the processing of foods such as livestock meat and vegetable proteins.

Conventionally known extraction methods for milo pigments include, for example, a method that takes advantage of the property of milo pigments to dissolve in water, alcohol, and propylene glycol and extracts them by combining these solvents [``Natural Coloring Handbook''] Published by Korin Shoten Co., Ltd., pages 363-364]
Alternatively, for example, an extraction method using 96% alcohol containing 1% concentrated hydrochloric acid ("Vopr. Pitan."
1978 (1) pp. 76-80). Mylo pigment can be obtained by concentrating the extract to remove impurities.
These methods for extracting mylopigments use organic solvents such as alcohol and therefore require equipment for solvent recovery, which has the drawback of increasing extraction costs. In addition, since the extract contains water-soluble impurities, it is difficult to separate it from the milo pigment, and the purity of the milo pigment cannot be improved, which has the drawback of limiting its use.

As a result of various studies aimed at solving the drawbacks of such conventional methods, the inventors obtained a Mylo pigment-containing aqueous extract by treating the Mylo pigment-containing substance with an aqueous alkali,
We have found a method to selectively precipitate the mylopigment by adjusting the pH of this extract to 4 or less, and at this time removing water-soluble impurities along with the aqueous solution, to obtain highly pure mylopigment pharmaceutically.

Here, the "milo pigment-containing material" as used in the present invention refers to milo itself or its acid, alkali,
Refers to products containing mylo pigments obtained by pre-treatment with other chemicals.

In the present invention, a caustic alkali aqueous solution, a sodium carbonate aqueous solution, etc. can be used as the aqueous alkali for obtaining the aqueous extract containing mylopigment.

The method of the present invention can be carried out, for example, by the following method.

Adding caustic alkali with a concentration of 0.1% or more, preferably 2 to 10%, in an amount of, for example, 5 times or more, preferably 7 times or more of Milo,
Extraction is carried out at a temperature of 45°C or higher, preferably 55-65°C, for 0.5-3.0 hours with or without stirring. After extraction, remove Milo by conventional methods such as filtration or centrifugation.
is removed to obtain a reddish-brown extract. This extract contains impurities such as proteins and sugars. To remove impurities, concentrated hydrochloric acid or other inorganic acid is added to the extract to adjust the pH to below 4, and more preferably in the range of 1 to 3. Since the Mylo pigment becomes insolubilized, it is separated as a precipitate or separated by centrifugation.
This yields purified mylopigments.

If you want to obtain a Mylo pigment with even higher purity, add 5 to 10 times the volume of a 0.2% sodium carbonate aqueous solution to the precipitate separated above, and heat it at about 80°C for 1 hour to obtain a Milo pigment. It is preferable to extract, cool, separate, add hydrochloric acid or other inorganic acid to the liquid to adjust the pH to 3, and take the insolubilized mylo pigment concentrate.

The mylo pigment precipitate or concentrate purified as above is optionally dried and then mixed with propylene glycol containing 3% soda carbonate/
Add water (15:85v/v) and then heat to about 80℃ for about 30 minutes.
By heating for several minutes, cooling, and removing precipitated impurities by filtration or the like, a liquid similar to a commercially available Milo-containing liquid can be obtained.

As mentioned above, the purification method by insolubilization of mylopigments by pH adjustment is effective in itself and can be carried out repeatedly, but it can also be combined with other purification methods, such as treatment of the extract with enzymes such as protease or protease/amylase. Alternatively, it can also be carried out in combination with, for example, conventional dye extraction methods using water, alcohol, propylene glycol, etc. In this case, a highly pure dye can be easily obtained in a short process. When combined with enzyme treatment, the extract extracted with caustic alkali is treated with hydrochloric acid.
Adjust the pH to 7.0, add protease to this,
The mixture is reacted overnight (16 hours) at 37°C, a supernatant is added to the reaction and filtered. When concentrated hydrochloric acid is added to the solution to adjust the pH to 3, the Mylo pigment is precipitated separately. This precipitate is separated by centrifugation. The mylo pigment precipitate or concentrate purified as described above is dried if necessary, and then propylene glycol/water (15:85 v/v) containing 3% sodium carbonate is added to it, and then at about 80°C. After heating for about 30 minutes, the solution is cooled, and precipitated impurities are removed by filtration, etc., to obtain a solution similar to a commercially available Milo-containing solution.

Next, the present invention will be explained with reference to Examples.

Example 1 Milo = 100g and 700ml of 0.7% caustic soda aqueous solution
was added and the mixture was heated at 60°C for 1 hour.
After cooling, 13 ml of concentrated hydrochloric acid was added to the extract from which solid residues were removed by centrifugation, and the resulting pigment-containing precipitate was collected.

Add 100ml of 0.2% sodium carbonate aqueous solution to the precipitate,
The pigment was extracted by heating at 80°C for 1 hour. After cooling,
The extract was filtered, the pH was adjusted to 3 by adding hydrochloric acid, and the insolubilized dye concentrate was collected.

Propylene glycol/water (15:85v/v) containing 3% soda carbonate to dry mylo pigment
25 ml was added, the mixture was heated at 80°C for 30 minutes and after cooling was filtered to remove the dye solution (E10% 1 cm18, 470 nm,
pH7.0) 19g was obtained.

Example 2 Milo = 100g and 700ml of 0.7% caustic soda aqueous solution
was added and the mixture was heated at 60°C for 1 hour. After cooling, 11.3 ml of concentrated hydrochloric acid was added to the extract from which solid matter was removed by centrifugation to adjust the pH to 7.0. To this was added 0.10 g of Sumiteam MP (trade name of protease manufactured by Shin Nihon Kagaku Co., Ltd.), and the mixture was allowed to react at 37° C. overnight, and then filtered using Hyflo Supercel super-assistant. After adjusting the pH to 3 by adding 2 ml of concentrated hydrochloric acid to the solution,
After adding 50 ml of saturated saline and stirring, the precipitate was collected by centrifugation.

The precipitate was dried, 30 ml of propylene glycol/water (15:85 v/v) containing 0.2% soda carbonate was added, the mixture was heated at 60°C for 30 minutes, cooled and filtered to form a dye solution (E10% 1 cm18 , 470nm, pH7.0) 26g
I got it.

Example 3 600 ml of 96% alcohol containing 1% hydrochloric acid was added to 100 g of Milo and boiled for 2 hours. After cooling, the solid matter was removed and the liquid was concentrated under reduced pressure. Add 100ml of 2% caustic soda aqueous solution to the concentrate and dissolve it.
- Washed with 100 ml of hexane, then separated the aqueous phase, adjusted to pH 2 with hydrochloric acid, and collected the formed precipitate. Add 20ml of propylene glycol/water (15:85v/v) containing 1% soda carbonate to the precipitate and heat at 80°C.
After heating for 30 minutes, the mixture was cooled and filtered to obtain 15 g of a dye solution (E10% 1 cm17, 470 nm, pH 7.0).

Claims (1)

[Claims] 1. A Mylo pigment-containing aqueous extract obtained by treating a Mylo pigment-containing substance with an aqueous alkali is adjusted to pH 4 or less to selectively precipitate Mylo pigments and remove water-soluble impurities. Purification method of Mylo pigment.