JP2002069475A - Process for producing docosahexaenoic acid-rich oils and fats - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing oils and fats containing a high percentage of docosahexaenoic acid which enables high quality oils and fats with high content of DHA to be obtained from bonito oil or tuna oil at a high yield and a low cost. SOLUTION: Oils and fats which contain docosahexaenoic acid >=40 wt.% and of which the color, the anisidine value and the odor are improved are obtained by hydrolyzing bonito oil or tuna oil as raw material with use of lipase under the condition that the reaction temperature is 30-35 deg.C and the reaction time is 15-25 hour, eliminating water, enzyme protein or the like from the reaction system after the reaction is over and then processing the product by deoxidation, decoloration and deodorization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing docosahexaenoic acid-rich fats and oils, and more particularly to a method for producing docosahexaenoic acid-rich fats and oils in which bonito oil or tuna oil is used as raw material fat and docosahexaenoic acid is concentrated to 40% by weight or more. .

[0002]

2. Description of the Related Art Lipids of fish (fish oil) such as sardines, mackerel, saury and horse mackerel, or lipids of algae such as red algae and brown algae,
Constituent fatty acids such as lipids of crustaceans, shellfish and marine animals contain a large amount of polyunsaturated fatty acids (hereinafter abbreviated as PUFA). Of these, docosahexaenoic acid (hereinafter abbreviated as DHA) is an unsaturated fatty acid of the ω-3 series, and in recent years, its physiological activity has been attracting attention in relation to prostaglandins and thromboxanes. Characteristic physiological activities such as an improving effect and a preventive effect on circulatory diseases are recognized, and it is widely used as a material for general foods and feeds.

[0003] Heretofore, as a method of concentrating PUFA such as DHA in the form of fats and oils, there is conventionally known a method of selectively hydrolyzing using lipase as described in Japanese Patent Publication No. 4-16519. Have been. This utilizes the property that the ester bond between PUFA such as DHA and glycerin in constituent fatty acids such as fish oil is hardly or slightly hydrolyzed by lipase, and PUFA such as DHA is concentrated as glyceride. Things.

[0004] In the present application, fats and oils include not only triglycerides but also monoglycerides and diglycerides.

[0005]

However, when DHA is to be concentrated using bonito oil or tuna oil as a raw material by the lipase treatment method as described above, the water content of the bonito oil or tuna oil is high due to the characteristics of the fatty acid composition. When decomposing, the DHA purity does not easily rise above a certain level. This is because the lipase hardly acts on the saturated fatty acids contained in the skipjack oil or tuna oil under the reaction conditions.

That is, lipase has an optimum reaction temperature of 38 to 50 ° C. When a lipase is reacted in this range to hydrolyze bonito oil or tuna oil, the hydrolysis is carried out quickly, but the concentration of DHA is effective. Not.

[0007] Therefore, DH is actually obtained in the form of fats and oils from skipjack oil or tuna oil at the optimum reaction temperature range of lipase.
In order to concentrate A purity to 40% by weight or more, it is necessary to combine solvent fractionation and other steps such as enzymatic reaction, transesterification reaction, and synthesis method (dehydration condensation of free fatty acid with glycerin). And the yield of the resulting fats and oils is low. Therefore, the manufacturing cost becomes very high. In addition, quality deterioration during the processing process is inevitable.

[0008] When an oil or fat is used as a food, color and odor are regarded as important. On the other hand, fats and oils with a high degree of unsaturation, such as skipjack oil or tuna oil, are very susceptible to oxidation. That is, degradation of the product due to oxidation in the enzymatic reaction and the purification step becomes a problem.

Accordingly, unnecessarily prolonging the enzymatic reaction time leads to oxidation of fats and oils, resulting in qualities that are not suitable for use as foods, such as coloring and peroxide formation.

In addition, in the step of removing the free fatty acid, which is carried out after the enzymatic reaction, further coloring, accumulation of oxidized secondary products such as carbonyl compounds represented by indicators such as anisidine value, or oxidative deterioration caused by the accumulation. Odor is generated. Oils and fats exhibiting such properties are no longer valuable as foods, and further purification and utilization thereof are very expensive in terms of cost.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to obtain high-quality DHA-rich fats and oils from skipjack oil or tuna oil at a high yield and at low cost. It is an object of the present invention to provide a method for producing a docosahexaenoic acid-rich oil or fat which can be used.

[0012]

The present inventors have focused on the fact that the melting points of free fatty acids are different between saturated fatty acids and unsaturated fatty acids, and have found a method for producing fats and oils containing highly unsaturated fatty acids. As a result of intensive research on bonito oil or tuna oil as a raw material, and in the hydrolysis reaction by lipase, the reaction temperature is strictly controlled at low temperature,
Further, they found that by limiting the reaction time, it was possible to produce a fat or oil containing high-quality docosahexaenoic acid of 40% by weight or more, and completed the present invention.

[0013] That is, the present invention uses a bonito oil or tuna oil as a raw material, and controls the reaction temperature to 30 to 35 ° C and the reaction time to 15 to 25 hours in the hydrolysis reaction by lipase to form the reaction product. By extracting saturated fatty acids from the reaction system preferentially out of the free fatty acids, it is possible to produce fats and oils containing docosahexaenoic acid in an amount of 40% by weight or more. At the same time, by conducting the reaction at a low temperature, oxidation of fats and oils during the reaction is suppressed, which can ultimately contribute to improvement of product quality, for example, reduction of product color, anisidine value and odor represented thereby. Becomes

Hereinafter, the present invention will be described in detail.

The bonito oil or tuna oil, which is the raw material, contains 2 DHA.
It is contained in an amount of 0 to 28% by weight, and preferably has a higher DHA content in consideration of the concentration efficiency. In addition, it is desirable that the resin does not undergo thermal degradation during the purification process, and the anisidine value, which is an index of the secondary oxidation product, needs to be 40 or less, and preferably 35 or less.

When the lipase hydrolysis method is used, the lipase to be used may be a genus of Candida ,
Rhizopus (Rhizopus) genus Pseudomonas (Pseudomonas)
Those derived from the genus can be used. It is a necessary condition that the lipase used in the present invention is an enzyme having low reactivity to hydrolyze the DHA ester.

The reaction conditions of the lipase used in the present invention are as follows.

The amount of lipase used for the raw material for oils and fats varies depending on the type of the enzyme.
It needs to be adjusted to ~ 25 hours. Generally, it is in the range of 10 to 2000 units (U) per 1 g of fats and oils,
Preferably it is 50 to 600 units (U). One unit (U) is 1 μmol / min using olive oil as a substrate.
The amount of the enzyme that releases fatty acids.

The reaction temperature must be strictly controlled.

The enzymatic hydrolysis reaction reaches a maximum in the range of 38 to 50 ° C. and hydrolyzes fats and oils most often, but is not preferred in terms of DHA concentration. In addition, when the hydrolysis reaction is performed at a low temperature of 28 ° C. or less, the reaction requires time,
It is not preferable in terms of quality and economy.

Therefore, the temperature in the enzymatic reaction is 30 to 35 ° C.
And temperature changes need to be kept within this range. This reaction is an exothermic reaction, and the temperature of the reaction solution gradually increases as the hydrolysis proceeds, so that temperature control during the reaction is necessary.

The amount of water to be added is 50 to 200% by weight based on the fat or oil.
And preferably 100 to 120% by weight.

The pH is preferably in the range of 5.0 to 7.0, and more preferably in the range of 6.5 to 7.0. It is effective to use a buffer to adjust the pH.

In order to promote the reaction more effectively, an emulsifier can be used.

The reaction may be carried out in the atmosphere. However, when a large amount of PUFA is contained, the deterioration of the product can be prevented if the reaction is carried out under an inert gas, for example, an atmosphere of nitrogen gas or argon gas. Further, as an antioxidant, for example, tocopherol, catechins, BHA (butylhydroxyanisole), BHT (dibutylhydroxytoluene) and the like may be used in combination.

The reaction is desirably agitated, but the reaction can be carried out in an emulsified state. The reaction may be a batch system, but an immobilized enzyme column may be used as a continuous system.

The degree of hydrolysis can be determined by sampling the hydrolyzed oil during the reaction and measuring the acid value. The resulting DHA fat yield can be estimated from the degree of decomposition of the hydrolyzed oil, that is, the acid value of the hydrolyzed oil.
An arbitrary acid value can be set according to the DHA purity of the feedstock oil and the desired product DHA purity, and the acid value is generally 80 to 130.

Since the above-mentioned hydrolyzed fat and oil mixture contains free fatty acids in addition to the objective DHA-rich fat and oil, it is necessary to remove the free fatty acids in order to obtain a product. As a method for removing fatty acids, in addition to the commonly used alkali deoxidation method, molecular distillation method, solvent extraction method, ion exchange resin method, and low-temperature solvent fractional crystallization method, supercritical carbon dioxide gas extraction method or these methods Combined methods can be applied.

Subsequently, the desired product can be obtained by performing an adsorbent treatment and a steam distillation treatment for decolorization and deodorization. The order and method of each step after the lipase treatment are not particularly limited.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0031]

EXAMPLE 1 0.05 g of lipase powder derived from the genus Candida was dissolved in 100 g of water, and bonito oil (DH) was further dissolved.
A: 25.2% by weight, anisidine value: 38.1) 100 g was mixed and subjected to an enzymatic reaction with stirring at 32 ° C. and pH 7.0 for 24 hours to obtain a hydrolyzed oil.

Next, the hydrolyzed oil is centrifuged to collect an oil layer, and then glycerin and enzyme proteins are removed by washing with water.
Vacuum degree 0.6Ps (0.005mmHg), evaporation surface temperature 180 ℃, flow rate 60g
By treating under the conditions of / h, free fatty acids were distilled off and removed. The oils and fats obtained as the residue were decolorized with activated carbon, and subjected to decompression steam deodorization at a vacuum of 650 Ps (5 mmHg) and a temperature of 170 ° C. to obtain a product.

The product had a DHA purity of 42.0% by weight, an anisidine value of 32.0 and a Gardner color of 4, and a liquid oil having almost no taste and odor was obtained.

[0034]

Example 2 0.05 g of lipase powder derived from the genus Candida was dissolved in 100 g of water, and tuna oil (DHA:
A mixture of 100 g of 23.2% by weight and anisidine value: 10.5) was subjected to an enzymatic reaction under stirring at 30 ° C. and pH 7.0 for 24 hours to obtain a hydrolyzed oil.

Next, the hydrolyzed oil is centrifuged to collect an oil layer, and then glycerin and enzyme proteins are removed by washing with water. Then, using a falling film molecular distillation apparatus, the degree of vacuum is set to 0.6 Ps (0.005 mmHg). Free fatty acids were distilled off and removed by treatment under the conditions of an evaporation surface temperature of 180 ° C. and a flow rate of 60 g / h. The oils and fats obtained as the residue were decolorized with activated clay, and deodorized under reduced pressure steam at a vacuum of 650 Ps (5 mmHg) and a temperature of 170 ° C. to obtain a product.

The product had a DHA purity of 40.8% by weight, an anisidine value of 9.3 and a Gardner chromaticity of 3, and a liquid oil having almost no taste and odor was obtained.

[0037]

Comparative Example 1 0.05 g of lipase powder derived from the genus Candida was dissolved in 100 g of water, and bonito oil (DHA:
A mixture obtained by mixing 100 g of 25.2% by weight and anisidine value: 40.5) was subjected to an enzymatic reaction while stirring at 45 ° C. and pH 7.0 for 24 hours to obtain a hydrolyzed oil.

Next, the hydrolyzed oil was centrifuged to collect an oil layer, and then glycerin was removed by washing with water. Then, using a falling thin film molecular distillation apparatus, the degree of vacuum was 0.6 Ps (0.005
Free fatty acids were removed as a distillate by treatment under the conditions of mmHg), an evaporation surface temperature of 180 ° C, and a flow rate of 60 g / h. Decolorize oils and fats obtained as a residue with activated carbon, vacuum degree 65
Decompression steam deodorization was performed at 0 Ps (5 mmHg) and a temperature of 170 ° C. to obtain a product.

The quality DHA purity 35.1% by weight of the product, anisidine value 86.2, a Gardner chromaticity 12 ^+, was obtained oil with a specific irritating odor.

[0040]

As described above, according to the present invention, the starting bonito oil or tuna oil is reacted at a reaction temperature of 30 to 35 ° C. and a reaction time of 30 minutes.
Hydrolysis by lipase under the conditions of 15 to 25 hours, after completion of the reaction, removal of water, enzyme proteins, etc. from the system, and further through each step of deacidification, decolorization and deodorization, docosahexaenoic acid is reduced to 40% by weight. As described above, docosahexaenoic acid-containing fats and oils having improved color, anisidine value and odor are obtained, so that high-quality DHA-rich fats and oils can be obtained from skipjack oil or tuna oil in good yield and at low cost. It has effects such as being able to do.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C12P 7/64 C12P 7/64 (72) Inventor Seiji Norinobu 95-7 Minoki-cho, Fukuyama-shi, Hiroshima Ikeda Food (72) Inventor Mitsumasa Mankura 95-7, Minokiki-cho, Fukuyama-shi, Hiroshima F-term (reference) 4B064 AD85 CA21 CB03 CC01 CC06 CC07 CD25 CE01 CE03 CE20 DA01 DA10 4H059 BB05 BB07 BC06 BC48 CA38 DA08 DA09 DA30 EA23 EA24 EA25

Claims (3)

[Claims] Claims 1. A bonito oil or tuna oil as a raw material is reacted at a reaction temperature of 30.
By hydrolyzing with lipase under the conditions of ~ 35 ° C and reaction time of 15 to 25 hours, after completion of the reaction, water, enzyme proteins and the like are removed from the system, and further through deoxidation, decolorization and deodorization steps, A method for producing a docosahexaenoic acid-rich oil / fat containing 40% by weight or more of docosahexaenoic acid and having improved color, anisidine value and odor. 2. The docosahexaenoic acid-rich fat or oil according to claim 1, wherein the raw bonito oil or tuna oil contains docosahexaenoic acid in an amount of 20 to 28% by weight and an anisidine value of 40 or less. Production method. 3. The method according to claim 1, wherein the docosahexaenoic acid-containing fat or oil has a hue of 6 or less according to the Gardner method and an anisidine value of 35 or less.