JPH0751055B2 - Method for extracting blue pigment from cyanobacteria - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for selectively extracting a blue pigment from cells of cyanobacteria.

[Conventional technology]

The blue pigment containing phycocyanin as a main component is contained in edible algae such as cyanobacteria, and has attracted attention as a safe edible natural blue pigment.

Algae such as cyanobacteria contain green pigments (chlorophyll, etc.) and yellow pigments (carotenoids) as pigment components in addition to phycocyanin. When extracting blue pigments from algae, high yields of blue pigment are obtained. It is desirable to satisfy both of extraction at a rate and extraction of a blue pigment selectively with respect to a green pigment and a yellow pigment at the same time.

New Food Industry Vol.21, No.2, 43-46, the extraction process,
A phycocyanin extraction step comprising a separation step, a purification step, etc. is described. However, the type of extractant is not specifically described in this document, and the treatment of algal cells is not described at all.

Japanese Patent Application Laid-Open No. 52-134058 describes a method for extracting a blue dye from Spirulina using a buffer solution of pH 4 to 4.
Further, JP-A-55-144868 describes a method in which cyanobacteria are treated with an aqueous phase containing calcium ions and then phycocyanin is extracted with an alkaline aqueous phase.
However, in all of these methods, the extraction yield is not always sufficient because the extraction is performed without crushing the algal cells. Further, since a buffer solution or an alkaline aqueous solution is used as the extractant, the buffer agent or the alkaline component in the extractant must be removed by a method such as dialysis in the production of the product dye, and therefore, However, the process is complicated, it takes a long time to produce the dye, and the production cost is high.

[Problems to be solved by the invention]

Therefore, the present invention seeks to provide a method for selectively extracting blue pigment from cyanobacterial cells in a simple process with good yield and selectivity.

[Means for solving problems]

In the method for extracting a blue pigment from cyanobacterial cells, (1) a step of drying a raw material alga to obtain a dry powder; (2) heat treating the dry powder at 60 ° C to 150 ° C. And (3) obtaining an aqueous solution of a blue dye from the heat-treated product.

[Specific explanation]

In the method of the present invention, cyanobacteria are used as a raw material.
Various cyanobacteria can be used, and a representative example thereof is algae of the genus Spirulina. The algal cells used as a raw material may be composed of wet cells separated from the algal culture solution, or may be dried once.

The raw material alga can be used without crushing, but preferably, an aqueous suspension of the raw alga is prepared and the cells are crushed. As a method for crushing cells, any method commonly used for crushing algal cells can be used, and preferable examples thereof include a wet ball mill method and an ultrasonic treatment method. In the wet ball mill method, a large number of glass beads are enclosed in a closed cylinder having a cooling jacket and mixed and rotated together with an introduced aqueous suspension of cells. The sonication method is performed by irradiating the aqueous suspension of cells with ultrasonic waves. Various aqueous solutions can be used as the medium of the aqueous suspension in these methods, but it is most convenient to use water. In either method, phycocyanin is likely to be denatured due to heat generated by the treatment in the cell disruption step, and therefore in order to prevent this, it is preferable to perform the cell disruption treatment while cooling to around room temperature or lower temperature.

Next, the alga body or its crushed product is dried. This drying can be performed by any conventional method such as spray drying or freeze drying. From an industrial point of view, spray drying is preferred. The spray drying method, for example, the inlet temperature 100 ℃ ~ 170 ℃,
It is preferably carried out at 135 ° C to 150 ° C.

Next, the dried powder of algal cells is heat treated. The main purpose of this heat treatment is to modify chlorophyll, carotene and the like so that they can be easily separated and removed from the blue dye in the subsequent step. Therefore, as heating conditions, phycocyanin, which is the main component of the blue pigment, is not substantially modified, and chlorophyll,
It is necessary to select conditions such that the pigment component such as carotene is modified. As a result of various studies to find out such conditions, the present inventor has found that the above object can be achieved by heating at 60 ° C. to 150 ° C. for a short time. This heat treatment is preferably performed at 100 ° C to 120 ° C. The time of the heat treatment can be arbitrarily selected in relation to the heating temperature, but it is preferably 10 minutes to 2 hours. When the heating temperature is high, it is short, and when the heating temperature is low, it is long.

A powder containing a blue dye is obtained by this method. This treatment heat-denatures chlorophyll and carotene to render it insoluble in water.

Then, the heat-treated product is extracted with water to obtain an aqueous solution containing a blue pigment and substantially not containing a green pigment (chlorophyll) and a yellow pigment (carotene). The extraction conditions, that is, the ratio of water to powder, the extraction temperature and the extraction time are not particularly critical, but the weight ratio of powder to water is 1: 5.
Conveniently, the extraction temperature is 5 ° C to 30 ° C and the extraction time is 1 minute to 60 minutes. During this extraction, it is preferable to perform continuous or intermittent gentle agitation in order to improve the contact between the powder and water as an extractant.
By this extraction step, the blue pigment in the heat-treated powder selectively dissolves water, and other pigments such as green pigment and yellow pigment are dispersed as fine particles together with cells or cell debris. By removing insoluble matter from this suspension according to a conventional method,
An aqueous solution containing a blue dye and substantially free of other dyes such as a green dye and a yellow dye is obtained. This insoluble matter can be removed by a conventional method such as centrifugation or filtration.

The aqueous solution of blue dye thus obtained is a buffer,
Since it does not contain salts and other components artificially added such as alkali, it can be dried without further purification to obtain a blue dye powder product. For this drying treatment, conventional methods such as freeze drying and spray drying can be used. Before this drying treatment, the aqueous solution can be concentrated by a conventional method such as ultrafiltration.

The powder product thus obtained comprises a blue pigment,
It contains substantially no other pigment components such as green pigments (chlorophyll etc.) and yellow pigments (carotene). As a product other than the blue pigment, this powdered product contains a small amount of soluble proteins, vitamins, etc. derived from the raw cyanobacteria, but since these are nutritional ingredients, it does not matter if they are present in the blue edible pigment product. .

In the separation step, the residue after separating the blue pigment contains proteins, polysaccharides, carotene, chlorophyll, vitamins, minerals, etc., which can be used as it is or as a feed, It can also be used as a raw material for producing carotene.

〔The invention's effect〕

In the present invention, since the other dyes are solidified, fixed to a solid or thermally denatured by heat treatment of the dried product, only the blue dye can be selectively extracted. Furthermore, since water is used as an extraction solvent for the blue dye, dialysis and other post-treatments are unnecessary, and the blue dye can be recovered by a very simple process. The main component of the blue pigment thus obtained is phycocyanin, which is used as it is as an edible natural pigment.

〔Example〕

Example 1. 150 g of commercially available bulk Spirulina powder was suspended in 850 ml of deionized water, and this suspension was continuously wet ball mill (trade name: DYNO
-MILL KDL type) and repeated trituration three times. The liquid inflow rate was 50 ml / min, and glass beads with a diameter of 0.75 to 1.0 mm were enclosed in about 83% of the cylinder capacity, and the outside of the cylinder was water-cooled. Water was added to the slurry obtained from the cylinder outlet to make it 2800 ml, and a spray dryer (inlet temperature 140 ° C,
Spray drying was performed at an outlet temperature of 70 ° C.) to obtain 115 g of a blue-green powder.

3.0 g of this powder was placed in a 50 ml Erlenmeyer flask and heated in a dryer kept at a predetermined temperature for a predetermined time. 30 ml of deionized water was added to this flask, and the mixture was stirred and extracted with a magnetic stirrer for 10 minutes and then centrifuged (about 10,000 G, 20 minutes). When the amounts of phycocyanin and carotene in the blue pigment extracted from the visible absorption spectrum of the supernatant were calculated, the results shown in the following table were obtained.

In the table, C / F is the ratio of the absorbance at 438 nm (absorption by carotene; C) and the absorbance at 618 nm (absorption by phycocyanin; F), which is an index of color tone, and the smaller this value is, the better the color tone is, 0.1 The following are particularly preferred. F
(%) Is the% of the F value of the extract from the heated sample with respect to the F value when extracted without heat treatment,
It is an index of the extraction yield of phycocyanin.

Example 2. 250 g of commercially available bulk Spirulina powder was suspended in 1500 ml of deionized water, and the cells were crushed and dried in the same manner as in Example 1 to obtain 190 g of a blue-green powder. The cell disruption rate was 100% when observed under a microscope. 145g of this crushed Spirulina powder at 120 ° C
After heating for 30 minutes in a dryer kept at 137g, the weight is 137g.
Became. Add 1370 ml of deionized water to this and stir for 10 minutes to extract the dye, centrifuge (about 9500 G, 20 minutes) and obtain the supernatant with a spray dryer (inlet temperature 140 ° C, outlet temperature 65 ° C). As a result, 35 g of a blue dye powder was obtained.
The C / F (absorbance ratio) of the aqueous solution of this dye was 0.064.

Example 3 3.0 g of commercially available Spirulina bulk powder was heated as it was at 120 ° C. for 30 minutes, 30 ml of deionized water was added, the mixture was extracted with stirring for 10 minutes, and centrifuged (10,000 G, 20 minutes) to obtain a blue aqueous solution. When the absorption spectrum of this aqueous solution was measured, the C / F was 0.095.
The phycocyanin content was 63% in the case of no heat treatment, and 56% in the case of cell crushing and heat treatment. It should be noted that the solution of the aqueous solution extracted without heating this bulk powder
C / F showed a value of 0.207.

Example 4 A blue dye was extracted by the same method (heat treatment at 100 ° C. for 1 hour) as in Example 1 except that a phosphate buffer (pH 6.0, 0.02M) was used as an extraction solvent. The amount of phycocyanin in the solution was 92% of that obtained by extraction with deionized water without heat treatment, and the C / F was 0.088.

Example 5. Spirulina maxima harvested from a culture tank
maxima) After washing the alga body with water, about 3 times the weight of water was added to the alga body, the cells were crushed by the same method as in Example 1, and spray dried to obtain a blue-green powder. 2.50 g of this powder in a dryer
After heating at 0 ° C. for 30 minutes, 25 ml of deionized water was added, the mixture was stirred for 10 minutes, and a blue supernatant was obtained by centrifugation (about 10,000 G, 20 minutes). C / F calculated from visible absorption spectrum of supernatant
The value of was 0.089. On the other hand, the C / F of the supernatant when extracted without heat treatment was 0.409.

Claims (5)

[Claims] 1. A method for extracting a blue pigment from cyanobacterial cells, comprising the steps of (1) drying a raw alga to obtain a dry powder; and (2) heat treating the dry powder at 60 ° C. to 150 ° C. And (3) obtaining an aqueous solution of a blue dye from the heat-treated product. 2. The method according to claim 1, wherein the cyanobacteria is Spirulina. 3. The method according to claim 1, wherein the algal cells are crushed by a wet ball mill before being dried. 4. The method according to claim 1, wherein the drying is performed by spray drying. 5. The method according to claim 1, wherein the heating is performed for 10 minutes to 2 hours.