阅读说明：本技术 龙虾肝脏中不饱和脂肪酸的提取方法 (Method for extracting unsaturated fatty acid from lobster liver ) 是由 何山 李思莹 杲景蓉 张杨 于 2021-07-15 设计创作，主要内容包括：本发明提供了一种龙虾肝脏中不饱和脂肪酸的提取方法。该方法先对龙虾肝脏进行冷冻处理,再将龙虾肝脏进行干燥处理,最后加入超临界CO-(2)萃取设备中进行萃取。本发明的龙虾肝脏中不饱和脂肪酸的提取方法,通过各步骤的配合,先对龙虾肝脏进行冷冻处理,然后将冷冻处理后的龙虾肝脏进行干燥处理,最后加入超临界CO-(2)萃取设备中进行萃取,能够从龙虾肝脏中提取多不饱和脂肪酸,龙虾肝中的脂质提取率约97％。与传统的用热风干燥处理后,再用索氏提取法相比,提取的脂质中多不饱和脂肪酸含量显著增加。(The invention provides a method for extracting unsaturated fatty acid from lobster liver. The method comprises freezing lobster liver, drying, and adding supercritical CO 2 Extracting in an extraction device. The extraction method of the unsaturated fatty acid in the lobster liver comprises the steps of firstly freezing the lobster liver, then drying the lobster liver after freezing, and finally adding supercritical CO 2 The extraction equipment is used for extracting, polyunsaturated fatty acid can be extracted from the lobster liver, and the extraction rate of lipid in the lobster liver is about 97%. Compared with the traditional Soxhlet extraction method after hot air drying treatment, the content of polyunsaturated fatty acid in the extracted lipid is obviously increased.)

1. The extraction method of the unsaturated fatty acid in the lobster liver is characterized by comprising the following steps:

s1: freezing the lobster liver;

s2: drying the lobster liver processed in the step S1;

s3: adding the lobster liver processed in the step S2 into supercritical CO₂Extracting in an extraction device;

the drying treatment is hot air drying treatment or microwave-assisted hot air drying treatment.

2. The extraction process according to claim 1, characterized in that the temperature of the freezing treatment is lower than-10 ℃.

3. The extraction method according to claim 1, wherein the water content in the liver of lobster is less than or equal to 1% after the drying process in step S2.

4. The extraction method according to claim 1, wherein the temperature of the hot air drying treatment is 60 to 80 ℃.

5. The extraction method according to claim 1, wherein the time of the hot air drying treatment is 20 to 80 min.

6. The extraction method according to claim 1, wherein the temperature of the microwave-assisted hot air drying treatment is 60 to 80 ℃.

7. The extraction method according to claim 1, wherein the power of the microwave-assisted hot air drying treatment is 300 to 400W.

8. The extraction method according to claim 1, wherein in step S3, the extraction pressure is 20MPa to 40MPa, and the extraction temperature is 40 ℃ to 60 ℃.

9. The extraction method according to claim 1, wherein in step S3, CO is introduced into the extraction tank₂The flow rate of the water is 0.3 kg/h-0.5 kg/h.

10. The extraction method according to claim 1, wherein the extraction time in step S3 is 2 to 5 hours.

Technical Field

The invention belongs to the technical field of unsaturated fatty acid extraction, and particularly relates to an extraction method of unsaturated fatty acid in lobster liver.

Background

The polyunsaturated fatty acid is a straight-chain fatty acid which contains two or more double bonds and has a carbon chain length of 18-22 carbon atoms. Generally divided into OMEGA-3 (also written as OMEGA-3, w-3, n-3) and OMEGA-6, in polyunsaturated fatty acid molecules the double bond furthest from the carboxyl group is called OMEGA-3 on the 3 rd last carbon atom; on the sixth carbon atom, it is called ω -6. Usually synthesized by aquatic phytoplankton in cold regions. Polyunsaturated fatty acids play an important role in the prevention of diabetes, allergies and certain types of cancer, and have antithrombotic, antiarrhythmic and anti-inflammatory effects.

Lobster liver contains a large amount of omega-3 polyunsaturated fatty acids. It is reported that 10000 more tons of lobster processing waste including head, shell and liver are produced every year in the world, wherein the lobster liver accounts for 2% -5%. However, only about 25% of these wastes are used in finished products, almost exclusively in low commercial value items such as animal feed, aquaculture feed and biofertilizer; the other 75% of the feedstock is typically disposed of as waste, with disposal costs of up to $ 150/ton. Due to cost and environmental burden, the lobster processing industry is investigating how to utilize these processing by-products, particularly lobster liver, as a potential resource for the production of omega-3 lipid-rich products.

In the related technology, the extraction method of lobster liver lipid is mainly a chemical method, and the selection of solvent directly influences the extraction effect. Some organic solvents including acetone, ethyl acetate, hexane, isopropanol, methanol, methyl ethyl ketone, ethanol, etc. can be used in the food industry, while other organic solvents such as dichloromethane, dimethyl sulfoxide, and chloroform cannot be used in the food industry due to toxicity.

Disclosure of Invention

The present invention is directed to solving at least one of the above problems in the prior art. Therefore, the invention provides a method for extracting unsaturated fatty acid from lobster liver.

The extraction method of unsaturated fatty acid in lobster liver comprises the following steps:

s1: freezing the lobster liver;

s2: drying the lobster liver processed in the step S1;

s3: adding the lobster liver processed in the step S2 into supercritical CO₂Extracting in an extraction device;

the drying treatment is hot air drying treatment or microwave-assisted hot air drying treatment.

The method for extracting the unsaturated fatty acid from the lobster liver has at least the following beneficial effects:

the extraction method of the unsaturated fatty acid in the lobster liver comprises the steps of firstly freezing the lobster liver, then drying the lobster liver after freezing, and finally adding supercritical CO₂The extraction equipment is used for extracting, polyunsaturated fatty acid can be extracted from the lobster liver, and the extraction rate of lipid in the lobster liver is about 97%.

Compared with the traditional method of extracting unsaturated fatty Acid from lobster liver by using a Soxhlet extraction method after drying by hot air, the method for extracting unsaturated fatty Acid from lobster liver obviously increases the content of polyunsaturated fatty Acid, namely omega-3 fatty Acid, Eicosapentaenoic Acid (EPA for short), Docosahexaenoic Acid (DHA for short) and docosapentaenoic Acid (DPA for short) in extracted lipid.

According to the extraction method of the unsaturated fatty acid in the lobster liver, only a very small amount of toxic heavy metals such as lead, arsenic, mercury and cadmium are detected in the extracted lipid, compared with the traditional Soxhlet extraction method after hot air drying treatment, the content of the heavy metals is obviously reduced, and the application range and the application amount of the unsaturated fatty acid extracted by using the extraction method in different food production formulas are expanded.

In the extraction method, the lobster liver is frozen firstly, so that the storage life of the lobster liver is prolonged.

In the extraction method, the lobster liver is frozen and then dried. The liver of the dried lobster has important significance as the pretreatment for extracting the lobster liver lipid. Because the lobster liver does not contain water basically on the premise of extracting the lobster liver lipid, the water content of the dried lobster liver is less than or equal to 1 percent, and the method accords with the premise of extracting the lobster liver lipid. If the lobster liver is not dry, the water content of the lobster liver is about 80%, which does not meet the premise of extracting the lobster liver lipid and cannot be extracted.

The drying treatment is hot air drying treatment or microwave-assisted hot air drying treatment.

The drying treatment is performed in order to reduce the water content in the liver as much as possible.

The hot air drying is the most common drying mode at present, and has the characteristics of high thermal efficiency, high production capacity, convenient operation and the like. However, if the hot air drying time is too long, the liver of the lobster is not oxidized with fatty acid and becomes saturated fatty acid, so that the omega-3 fatty acid or the omega-6 fatty acid, etc. are not seen. Therefore, the time for hot air drying should be appropriate.

The microwave-assisted hot air drying is to load microwaves on the basis of hot air drying. The microwave-assisted hot air drying has the advantages of high drying speed, short drying time, easiness in temperature control, uniformity in drying and the like, is widely applied to food drying, and can keep the color, the fragrance and the taste of food and lose alkaline nutrients.

The microwave-assisted hot air drying is adopted, so that the time required for drying the lobster liver by using the traditional hot air until the water content is less than or equal to 1 percent can be obviously shortened, and the problem that the un-neutralized fatty acid in the lobster liver is oxidized into saturated fatty acid in the drying process can be avoided.

According to some embodiments of the invention, the temperature of the freezing process is below-10 ℃.

According to some embodiments of the invention, the temperature of the freezing process is below-20 ℃.

According to some embodiments of the invention, the time of the freezing process is greater than 5 hours.

According to some embodiments of the invention, the time of the freezing process is greater than 8 hours.

According to some embodiments of the invention, the temperature of the hot air drying is 60 ℃ to 80 ℃.

According to some embodiments of the invention, the temperature of the hot air drying is 70 ℃.

According to some embodiments of the invention, the time of the hot air drying is 40min to 80 min.

According to some embodiments of the invention, the hot air drying time is 60 min.

According to some embodiments of the invention, the temperature of the microwave-assisted hot air drying is 60 ℃ to 80 ℃.

According to some embodiments of the invention, the temperature of the microwave-assisted hot air drying is 70 ℃.

According to some embodiments of the invention, the microwave-assisted hot air drying has a power of 300W to 400W.

According to some embodiments of the invention, the microwave-assisted hot air drying has a power of 350W.

According to some embodiments of the invention, the microwave-assisted hot air drying is performed for a time period of 2min to 10 min.

According to some embodiments of the invention, the microwave-assisted hot air drying time is 7 min.

According to some embodiments of the present invention, the water content of the liver of the lobster after the drying process is less than or equal to 1% in step S2.

According to some embodiments of the invention, in step S3, the extraction pressure is 20MPa to 40MPa and the extraction temperature is 40 ℃ to 60 ℃.

According to some embodiments of the invention, in step S3, CO₂The flow rate of the water is 0.3 kg/h-0.5 kg/h.

According to some embodiments of the invention, in step S3, CO₂The flow rate of (2) was 0.434 kg/h.

According to some embodiments of the invention, in step S3, the extraction time is 2h to 5 h.

According to some embodiments of the invention, in step S3, the extraction time is 4 h.

According to some embodiments of the invention, in step S3, the lobster liver after drying process is added with supercritical CO₂The extraction is carried out in extraction equipment, and the specific method comprises the following steps:

the dried lobster liver was placed in an extraction vessel, and the void volume at both ends of the extraction vessel was filled with washed sand and glass wool layers.

To ensure good contact between the sample and the supercritical solvent,standing for 20min, and opening supercritical CO₂Needle valves of the extraction system release the extracted lipids.

Supercritical CO₂The extraction system performs lipid extraction.

Continuously discharging CO in supercritical state from container to be extracted₂Thereafter, the extracted lipids were collected in pre-weighed dark glass bottles.

Lipid collection vials were weighed every hour to calculate lipid recovery. Extraction under each condition was repeated in triplicate.

Supercritical fluids can be used at moderate temperatures to provide an oxygen-free medium during extraction to reduce lipid oxidation. Furthermore, supercritical fluids allow selective extraction of low polarity lipid compounds, avoiding co-extraction of polar impurities, such as some organic derivatives containing heavy metals.

According to some embodiments of the invention, the lobster is crayfish, also known as Australian lobster.

The crayfish liver comprises proteins, minerals, lipids, water and other substances.

The liver of lobster usually contains four heavy metal elements of lead, cadmium, arsenic and mercury, wherein the content of arsenic and cadmium is quite high, and the lobster is harmful to human health. In the processing process of lobsters, heavy metal pollutants, particularly arsenic and cadmium in the lipid, need to be removed in order to utilize the lobster liver grease.

Drawings

FIG. 1 shows the measurement results of the total fatty acid content of lipids in the extract under different extraction pressures.

FIG. 2 is a diagram showing the contents of three fatty acids in lipids extracted by different extraction methods.

FIG. 3 is a graph showing the omega-3, DHA, EPA and DPA content of lipids extracted by different extraction methods.

FIG. 4 is a graph showing the heavy metal content of lipids extracted by different extraction methods.

FIG. 5 is a graph showing the total arsenic and inorganic arsenic content of lipids extracted by different extraction methods.

Detailed Description

The following are specific examples of the present invention, and the technical solutions of the present invention will be further described with reference to the examples, but the present invention is not limited to the examples.

In the examples, the apparatus for hot air drying treatment was a hot air dryer model EH manufactured by Moretto corporation.

The microwave-assisted hot air drying equipment is a microwave-assisted hot air dryer of a Milestone company with the model number of Ethos up.

Examples

The embodiment extracts unsaturated fatty acid in lobster liver, and comprises the following steps:

s1: freezing the lobster liver;

s2: drying the lobster liver processed in the step S1;

s3: adding the lobster liver processed in the step S2 into supercritical CO₂Extracting in an extraction device;

the drying treatment is hot air drying treatment or microwave-assisted hot air drying treatment.

The lobster liver used in this example was crayfish liver.

In step S1, fresh lobster liver is frozen in a-20 deg.C refrigerator for 8 h.

In step S2, when the drying process is hot air drying, the drying process is carried out in a hot air drying apparatus at 70 ℃ for 60 min.

When the drying treatment is microwave-assisted hot air drying treatment, the sample is dried for 7min in a hot air drying instrument with microwave equipment added after transformation at 70 ℃ and 350W microwave power.

After drying, the lobster liver is stored in a vacuum sealed bag for later use.

In step S3, supercritical CO is used₂The method for taking polyunsaturated fatty acid from crayfish liver specifically comprises the following steps:

(1) the dried lobster liver was placed in an extraction vessel, and the void volume at both ends of the extraction vessel was filled with washed sand and glass wool layers. Standing for 20min to ensure good contact between the sample and supercritical solvent, and opening supercritical CO₂Needle valve of extraction systemReleasing the extracted lipids.

(2) Supercritical CO₂The extraction system performs lipid extraction.

(3) Continuously discharging CO in supercritical state from container to be extracted₂Thereafter, the extracted lipids were collected in pre-weighed dark glass bottles.

(4) Lipid collection vials were weighed every hour to calculate lipid recovery. Extraction under each condition was repeated in triplicate.

In step (1), the extraction apparatus was a supercritical CO2 extraction system (model SFE-27071) equipped with 100mL and 1000mL extraction vessels, which were 100mL vessels.

The relevant parameters of the apparatus were set specifically to a maximum flow rate of carbon dioxide of about 0.434kg/h, an extraction time of 240min and an extraction temperature of 50 ℃.

Firstly, the influence of different extraction pressures on the total fatty acid content after microwave-assisted hot air drying is compared. The extraction was adjusted to 25, 30 and 35MPa respectively.

The total fatty acid content of the lipid in the extract is detected, the result is shown in fig. 1, and according to fig. 1, the optimal extraction conditions are as follows: pressure 35MPa, CO₂The flow rate was 0.434kg/h, carried out at 50 ℃ for 4 h. The optimized optimal extraction conditions can extract 97% of total fatty acids.

The total fatty acids include saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids.

Four control tests were performed in this example, respectively:

after hot air drying pretreatment, supercritical CO₂The extraction rate of the extraction.

The extraction rate of Soxhlet extraction after the traditional extraction method, namely hot air drying pretreatment.

The extraction rate of Soxhlet extraction after microwave-assisted hot air drying pretreatment;

supercritical CO after microwave-assisted hot air drying pretreatment₂The extraction rate of the extraction.

In the four control groups, after microwave-assisted hot air drying pretreatment, supercritical CO was added₂The extracted oil has the best quality. The nutritional components in the oil are unsaturated fatty acids. Of all unsaturated fatty acids, the most nutritious are the polyunsaturated fatty acids. Of all polyunsaturated fatty acids, the most nutritious are the omega-3 unsaturated fatty acids. Of all the omega-3 unsaturated fatty acids, the most nutritious are DHA, EPA and DPA.

As shown in fig. 2, four groups of control experiments found that there was a significant difference in the quality of the oil extracted by the different methods.

Supercritical CO after microwave-assisted hot air drying pretreatment₂The content of monounsaturated fatty acid in the extracted oil is 42 percent, and the content of polyunsaturated fatty acid is 33 percent, which is far more than that of the traditional extraction method.

After the pretreatment of hot air drying, the monounsaturated fatty acid content of the soxhlet extracted grease is 20%, and the polyunsaturated fatty acid content is 7%.

After the pretreatment of hot air drying, the unsaturated fatty acid and polyunsaturated fatty acid contents of the soxhlet extracted oil are the lowest among the 4 extraction methods shown in the patent.

In addition, experimental tests show that in addition to the significant enrichment of polyunsaturated fatty acids, supercritical CO is obtained after microwave-assisted hot air drying pretreatment₂The extracted lipids also have the highest proportion of omega-3 fatty acids, accounting for 24% of the total fatty acids, far exceeding conventional extraction methods.

After the pretreatment of hot air drying, the omega-3 fatty acid content of the soxhlet extracted oil is 3%.

In the conventional extraction method, i.e., after hot air drying pretreatment, the contents of unsaturated fatty acids and polyunsaturated fatty acids in the soxhlet-extracted oil were the lowest among the four control groups. The same trend is also shown in the content of DHA, EPA and DPA. As shown in fig. 3. The fatty acid composition of the lipids extracted from the four control groups is shown in table 1.

TABLE 1

Another embodiment of the quality of the grease is the heavy metal content. Too high a heavy metal content may limit its use or damage the body by excessive intake. The low heavy metal content can ensure that the grease can be widely and more widely applied to various food production formulas.

As shown in fig. 4 and 5.

After hot air drying pretreatment, supercritical CO₂The extracted lipid contains cadmium 0.01mg/kg, lead 0.012mg/kg, and mercury 0.01 mg/kg.

The traditional extraction method, i.e. after hot air drying pretreatment, the Soxhlet extracted lipid has cadmium content of 0.27mg/kg, lead content of 0.022mg/kg and mercury content of 0.012 mg/kg.

After microwave-assisted hot air drying pretreatment, the content of cadmium in the Soxhlet-extracted lipid is 0.25mg/kg, the content of lead in the Soxhlet-extracted lipid is 0.019mg/kg, and the content of mercury in the Soxhlet-extracted lipid is 0.012 mg/kg.

Supercritical CO after microwave-assisted hot air drying pretreatment₂The extracted lipid contains cadmium 0.008mg/kg, lead 0.01mg/kg, and mercury 0.009 mg/kg.

For the content of total arsenic and inorganic arsenic, after microwave-assisted hot air drying pretreatment, supercritical CO is adopted₂The total arsenic content in the extracted lipid is also the lowest. Is far lower than the oil extracted by the traditional extraction method, namely the oil extracted by Soxhlet after the hot air drying pretreatment.

After hot air drying pretreatment, supercritical CO₂The total arsenic content in the extracted lipid is 2.2mg/kg, and the inorganic arsenic content is 0.05 mg/kg.

In the conventional extraction method, after hot air drying pretreatment, the total arsenic content in Soxhlet-extracted lipid is 31mg/kg, and the inorganic arsenic content is 0.22 mg/kg.

After the microwave-assisted hot air drying pretreatment, the total arsenic content in the Soxhlet-extracted lipid is 28mg/kg, and the inorganic arsenic content is 0.21 mg/kg.

Supercritical CO after microwave-assisted hot air drying pretreatment₂The total arsenic content in the extracted lipid is 2.1mg/kg, and the inorganic arsenic contentIt was 0.04 mg/kg.

The conventional extraction method described in this embodiment, that is, the method of pre-treating with hot air drying and then extracting lipid from lobster liver by soxhlet extraction, specifically includes the following steps:

(1) the hot air dried lobster liver was thoroughly homogenized and placed in a soxhlet sleeve.

(2) The cannula containing the sample was then placed in a hot extraction beaker while adding ether and locking into the hot extraction apparatus.

(3) Soxhlet extraction was performed.

In the step (1), the hot air-dried lobster livers are respectively 10 g.

In step (2), 90mL of diethyl ether was added.

In the step (3), the temperature for performing Soxhlet extraction is set to be 40 ℃, and the extraction time is 4 hours.

Finally, the amount of lipids obtained by this method was 2.43 g per 10g of dried lobster liver. Since the Soxhlet extraction method is a standard complete extraction method of oil and fat, 2.43 g of lipid/10 g of dried lobster liver was considered as an extraction rate of 100%.

The extraction method of the unsaturated fatty acid in the lobster liver comprises the steps of firstly freezing the lobster liver, then drying the lobster liver after freezing, and finally adding supercritical CO₂The extraction equipment is used for extracting, polyunsaturated fatty acid can be extracted from the lobster liver, and the extraction rate of lipid in the lobster liver is about 97%.

Compared with the traditional method of drying by hot air and then extracting by Soxhlet extraction, the content of polyunsaturated fatty Acid, namely omega-3 fatty Acid, Eicosapentaenoic Acid (EPA for short), Docosahexaenoic Acid (DHA for short) and docosapentaenoic Acid (DPA for short) in the extracted lipid is obviously increased. In addition, only a very small amount of toxic heavy metals such as lead, arsenic, mercury and cadmium are detected in the extracted lipid, and compared with the traditional Soxhlet extraction method after drying treatment by hot air, the content of the heavy metals is obviously reduced, and the application range and the application amount of the unsaturated fatty acid extracted by using the extraction method in different food production formulas are expanded.

The present invention has been described in detail with reference to the embodiments, but the present invention is not limited to the embodiments described above, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.