JP2002262788A - Simple method for fucoidan production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently extract fucoidan from brown algae. SOLUTION: This simple method for fucoidan production comprises (a) extracting an alga body of brown algae with 0.5-20 pts.wt. based on the brown algae of a neutral or weakly alkali aqueous solvent which contains hydrogen peroxide at 50-150 deg.C for >=15 minutes, (b) separating an extracted solution from the residue of the alga body of the brown algae, (c) removing a low molecular weight substance from the extracted solution by using a reverse osmosis membrane (RO membrane) or an ultrafiltration membrane (RF membrane) and (d) recovering fucoidan from the extracted solution. Fucoidan obtained by the method maintains approximately the same sulfate group considered to greatly contribute to the physiological activity of fucoidan as that of native fucoidan, has low arsenic and heavy metal contents and an excellent color tone and is useful as a food material, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for efficiently extracting fucoidan from brown algae. Fucoidan obtained by the method of the present invention is useful as a food material or the like.

[0002]

BACKGROUND OF THE INVENTION Brown algae include fucoidan which has various physiological functions and is used as a food or cosmetic material. Fucoidan is a sulfated polysaccharide containing fucose as a main component, and various physiological activities are known. Several techniques for the use of fucoidan and for extraction and purification are known. Many of these extraction and purification methods are hot water extractions under acidic conditions, and are characterized by extraction at pH 2 to 4 and 80 to 100 ° C. However, heat extraction under acidic conditions causes browning, which is problematic for use as food or cosmetics.

[0003] As a method for avoiding this problem, there is a method in which alginic acid or the like is co-precipitated with barium and purified after long-time extraction at room temperature in an acidic condition (Masaba Tayuki: JP-A-10-195106).
Alternatively, heat the acidic extract or the algae itself for a long time with hydrogen peroxide (weakly acidic pH 5-7, 20-40 ° C, 17 hours)
(Yakult Honsha Co., Ltd .: JP-A-10-19940). However, in these methods, a long time is required for the treatment and the treatment temperature is around room temperature, so that there is a possibility that a problem such as growth of microorganisms may occur during the treatment.

[0004] Polysaccharides extracted from brown algae are mainly composed of fucoidan and alginic acid.
Various low molecular substances and salts are also extracted together. When fucoidan is used as food or cosmetics, it is desirable that such dyes and various low-molecular substances are not contained as much as possible.

[0005] An ultrafiltration method or an alcohol fractionation method has been proposed for removing dyes and various low-molecular substances, but the ultrafiltration method is generally used in general from the viewpoint of a suitable manufacturing process and cost. However, alginic acid extracted together with fucoidan is in a sol state having a very high viscosity in a neutral region, so that a large load is applied during ultrafiltration. Therefore, the extract is brought to an acidic range of pH 3 to 4, and alginic acid is dissolved to lower the viscosity. However, under heating conditions in an acidic range of pH 3 to 4, fucoidan is reduced in molecular weight and partially desulfated, and native fucoidan cannot be obtained. In addition, there is a concern that leakage of fucoidan occurs during ultrafiltration due to the reduction in molecular weight, and the recovery rate of fucoidan is significantly reduced. Furthermore, desulfation is desirably as small as possible, considering that the physiological function of the sulfated polysaccharide also depends on the sulfuric acid content.

[0006]

SUMMARY OF THE INVENTION The inventors have been engaged in research on sulfated polysaccharides for many years. The extraction and desalting conditions of fucoidan, a sulfated polysaccharide, from various brown algae were examined.
Heat treatment with an extract of 7.0 to 8.0) yields a low-viscosity extract containing a high concentration of fucoidan, and the resulting extract is separated by ultrafiltration membrane (UF membrane) or loose reverse osmosis membrane (loose RO membrane). It was found that by removing unnecessary low-molecular substances using a membrane, fucoidan with high yield, less desulfation, and excellent color tone and safety could be obtained in a short time.
The present invention has been completed.

The present invention relates to (a) a method of preparing a brown algal alga body using a 0.5 to 20 parts by weight of a neutral or weakly alkaline aqueous solvent containing hydrogen peroxide for 50 to 100 parts by weight;
(B) separating the extract and the brown algal residue from the extract; (c) removing low molecular substances from the extract using a reverse osmosis membrane or an ultrafiltration membrane; And (d) a method for producing fucoidan from a brown algal alga body, comprising the step of recovering fucoidan from an extract.

The step (a) is a step of preparing an extract containing a high concentration of fucoidan having low viscosity and low desulfation from brown algae. Brown algae used as a raw material in the method of the present invention include mozuku, kelp, wakame, and honda straw. In the method of the present invention, it is preferable to use a mozuku rich in fucoidan as a raw material.

In the step (a), the viscosity is not so high because fucoidan in the brown algae is partially oxidatively decomposed by hydrogen peroxide to lower the molecular weight (for example, several thousand to several hundred thousand). Thus, an extract containing fucoidan at a high concentration can be obtained. Low molecular weight is preferable for increasing the extraction efficiency, and low viscosity is also preferable from the viewpoint of using a membrane in the subsequent step (c). In this step, alginic acid can also be decomposed.

[0010] The molecular weight of fucoidan having a reduced molecular weight is such that the molecular weight of a low-molecular substance containing salts and heavy metals, which is a problem when used in foods and cosmetics, is about 1000 Da or less. Membrane) or a reverse osmosis membrane (RO membrane), taking into account their removal.
It is preferable that it is above. From such a viewpoint, the upper limit of the concentration of hydrogen peroxide contained in the solvent may be determined. Hydrogen peroxide used in step (a) has a concentration of about 0.01 to 2.0% with respect to the system (refers to the concentration per volume of the raw material and the solvent, sometimes referred to as the final concentration),
Preferably, about 0.1-1.0%, more preferably about 0.1-0.3
%.

[0011] Hydrogen peroxide remaining in the extract can be decomposed by catalase or the like. The decomposition treatment may be performed at an appropriate time if necessary, but is preferably performed after the step (c) from the viewpoint of suppressing the growth of microorganisms.

In step (a), the use of a neutral or weakly alkaline (preferably weakly alkaline) aqueous solvent significantly reduces the major physiological activity of non-desulfated fucoidan, or even desulfated one. An extract containing fucoidan that is not impaired can be obtained. That is, the sulfuric acid content of fucoidan after this step is
The sulfate content of fucoidan carefully prepared by alcohol fractionation, ion exchange, affinity chromatography and gel filtration methods is almost the same, and can be very similar to fucoidan contained in mozuku.

The pH of the solvent used in step (a) is about 7.0
Above, preferably about 7.0-8.5, more preferably about 7.0-
8.0. In order to make the solvent have such a pH value, an alkali is added to the solvent as necessary. Alkali generally dissolves in a solvent and can change the solvent pH to a basic side, and includes sodium bicarbonate (sodium bicarbonate), sodium carbonate, ammonium carbonate, sodium phosphate, sodium hydroxide, and potassium hydroxide. . From the viewpoint of being widely used as a food additive, sodium bicarbonate (bicarbonate)
Is preferred. In the case of adding baking soda, the concentration of baking soda in the system (refers to the concentration per volume of the raw material and the solvent, sometimes referred to as the final concentration) is, for example, 0.01 to 500 mM,
More preferably 0.1-200 mM, most preferably about 1-100 mM
It is.

The ratio of the raw brown algae to the aqueous solvent in the step (a) is not particularly limited, but is usually 0.1% based on the weight of the brown algae.
1 to 40 parts, preferably 0.5 to 20 parts, more preferably 0.75 to
Use 10 parts by weight of solvent.

The heating in the step (a) is mainly performed to increase the efficiency of fucoidan extraction and to prevent the growth of microorganisms during the extraction. Heating temperature is about 50-100 ℃,
Preferably it is about 85-100 ° C. The processing time in the step (a) can be appropriately set using the amount of fucoidan extracted as an index, but is usually about 15 minutes or more, preferably about 30 to 240 minutes, more preferably about 60 to 120 minutes. Minutes.
In the step (a), an operation such as stirring or shaking to improve the extraction efficiency of fucoidan may be performed.

In the step (b), the extract containing fucoidan obtained in the step (a) is separated from a brown algal alga body residue,
This is a step of obtaining a fucoidan extract. Separation can be performed by a usual method used for the same purpose, for example, filtration, centrifugation, or the like.From the viewpoint of performing filtration and clarification in a single step, filtration using diatomaceous earth is performed. Is preferred.

The step (c) is a step of removing low-molecular substances from the extract containing fucoidan obtained in the step (b) using an appropriate membrane. The membrane used in the step (c) is not particularly limited as long as it can fractionate the low molecular weight fucoidan and the low molecular weight substance to be removed, but preferably a reverse osmosis membrane ("RO" membrane) Or an ultrafiltration membrane (UF membrane). The molecular weight cut off is, for example, about 10 kD
a or less, preferably about 5 kDa or less, and most preferably about 1 kDa or less (according to a general measurement method). The membrane material (eg, acetylcellulose-based, cellulose-based, sulfonated polyethersulfone-based, polyvinyl alcohol-based, polyamide-based) and form (eg, flat membrane, hollow fiber membrane, composite membrane having a support layer) are particularly limited. Not done. In addition, it is preferable to use a loose RO membrane from the viewpoint that low molecular substances can be removed at a relatively high pressure.

The substance to be removed in the step (c) is a low-molecular substance having a molecular weight of about 1000 Da or less, which is not preferable for use in foods and cosmetics, and removes brown pigments, salts and heavy metals (for example, arsenic). Including.

The treatment time in the step (c) can be determined as appropriate based on the removal rate of the low-molecular substance, the concentration rate of the fucoidan-containing extract, and / or the processing limit of the membrane used. For example, the arsenic content in the finally obtained dried fucoidan is about 5 ppm or less, the heavy metal content in the finally obtained dried fucoidan is about 2 ppm or less, and / or The process is terminated when concentration becomes difficult due to the membrane. The concentration ratio refers to a value calculated by (volume of extract before concentration / volume of extract after concentration). By this step, the concentration ratio can be generally at least about 2 times, preferably about 4 times or more, more preferably about 8 times or more, and most preferably
Concentrate to 10 times or more.

It is considered that the treatment in the step (c) can be carried out without imposing a large load on filtration, since fucoidan and alginic acid have been reduced in molecular weight in the step (a).

Step (d) is a step of recovering fucoidan from the extract from which low-molecular weight has been removed obtained in step (c). The recovery can be carried out by a usual method used for the same purpose, for example, freeze-drying, hot-air drying and the like.

If desired, a sterilization step can be added to the method of the present invention. Sterilization can be carried out by a usual method used for the same purpose, for example, by heating, and from the viewpoint of the risk of contamination, it may be carried out after step (c).

When it is desired to obtain fucoidan with less raw material odor and less unpleasant taste, a general operation performed for the purpose of decolorization and deodorization in the field of foods and pharmaceuticals can be added to the above steps. . For example, activated carbon, porous adsorption resin,
Ion exchange resin, dialysis, ultrafiltration, fractionation with ethanol, treatment with pyrosulfite, etc., treatment with hydrogen peroxide, and the like can be further performed.

In the fucoidan obtained by the method of the present invention, it is considered that the sulfate group, which is thought to greatly contribute to its physiological activity, is maintained almost similarly to native fucoidan, and the removal of brown pigment It is considered to be excellent in color tone due to, for example, it is useful as a pharmaceutical raw material, food (including beverage) material, and the like. In food,
Confectionery (eg, chewing gum, candy, jelly, biscuits, chocolate, rice crackers), dairy products (eg, yogurt), health foods (eg, capsules, tablets, powders), beverages (eg, soft drinks, milk drinks, vegetables)・ Fruit drinks, tea) and drinks are included.

[0025]

Next, the present invention will be described in detail with reference to Examples.
The present invention is not limited by these.

(1) Method: As a brown algae used as a raw material, a frozen mozuku produced in Tonga was used. It examined under the following extraction conditions. Condition 1: 100 g of mozuku, 100 ml of solvent. pH 7.5. Final concentration 10 mM baking soda 0.175% hydrogen peroxide. Extract at 90 ° C for 60 minutes. Condition 2: 100 g of mozuku and 100 ml of solvent. pH 7.5. Final concentration 10mM sodium bicarbonate 0.35% hydrogen peroxide. Extract at 90 ° C for 60 minutes.

After the extraction treatment, the extract was clarified by diatomaceous earth filtration and subjected to desalting and concentration treatment. This process includes
Microza UF ACP-3013 (manufactured by Asahi Kasei) as a UF membrane or NTR-7450HG (manufactured by Nitto Denko) as a loose RO membrane was used. After the desalting and concentration treatment, the remaining hydrogen peroxide was decomposed by catalase or the like, sterilized by heating, and then freeze-dried.

With respect to the obtained fucoidan, the fucose content (sulfuric acid-thioglycolic acid reaction method), the sulfuric acid content (rhizonic acid method), the color tone (color difference meter), etc., as well as the yield, concentration limit, etc., were examined. Products (prepared carefully by alcohol fractionation, ion exchange, affinity chromatography and gel filtration) and fucoidan (commercially available) prepared by acid heating extraction and evaluated.

(2) Result;

[0030]

[Table 1]

In the UF treatment, the transmission speed was high in both conditions 1 and 2. Concentration was possible up to 4 times under condition 1 and up to 8 times under condition 2. Under condition 1, the viscosity of the solution was high, and as the concentration proceeded, the pressure at the inlet of the filtration device increased, making it difficult to feed the solution. The yield was 1.23% under condition 1 and 0.31% under condition 2. When the molecular weight distribution of the permeate was analyzed by HPLC,
Leakage due to low molecular weight of fucoidan was confirmed.

In a loose RO membrane, the RO membrane has pressure resistance under condition 1, but the viscosity of the solution increases with the progress of concentration,
Concentration up to 10-fold was difficult. Under condition 2, a concentration of 10 times or more was possible.

As described above, the loose RO membrane treatment can withstand a pressure increase due to concentration to some extent due to the pressure resistance of the membrane. Further, as in condition 2, the concentration of hydrogen peroxide is increased to reduce the molecular weight of fucoidan. Since fucoidan can be recovered without leaking out, sufficient desalting and concentration could be performed.

(3) Evaluation of the prepared fucoidan;

[0035]

[Table 2]

The fucoidan prepared by the method of the present invention had a fucose content of 50.2 to 54.8%, all of which were higher than the fucoidan prepared by the acid heating extraction method. Arsenic,
Heavy metals have low values, confirming their superiority in terms of safety. As for the color tone, the brightness (L) was the highest, the red (a) was the second lowest value after the standard product, and the yellow (b) showed the highest value as compared with the standard product and the acid-heated extract (commercial product). .

As described above, the method of the present invention makes it possible to produce fucoidan which is excellent in quality and safety as a food material.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hitoshi Kume 1-13-12 Kamihei, Fussa-shi, Tokyo (72) Masaaki Yamazaki 1-1-13-12-204, Nishikicho, Tachikawa-shi, Tokyo F-term (reference) 4B041 LD03 LD10 LH10 LP05

Claims (4)

[Claims] 1. A method for producing fucoidan from a brown algal alga body, comprising the steps of: (a) adding 0.5 to 20 parts by weight of a brown algal alga body to a neutral or weakly alkaline aqueous solvent, (B) Separating the extract from the brown algal algal residue; (c) extracting the reverse osmosis membrane (RO membrane) or the extract from the extract. Ultrafiltration membrane (U
F membrane) to remove low molecular weight substances; and (d) recovering fucoidan from the extract.
The manufacturing method. 2. In the step (a), a brown algal alga body is
0.75 to 10 parts by weight of an aqueous solvent having a pH of 7.0 to 8.0,
2. The method according to claim 1, wherein the extraction is carried out at 85-100 [deg.] C. for 30-240 minutes using a hydrogen peroxide having a final concentration of 0.01-2.0% (preferably 0.1-1.0%). 3. The method according to claim 1, wherein the separation of the extract and the brown algal algae residue in the step (b) is filtration using diatomaceous earth. 4. The method according to claim 1, wherein a reverse osmosis membrane (preferably a loose RO membrane) is used in the step (c).