CN1273494C - Production of K-kala glue - Google Patents

Abstract

The present invention relates to a method for preparing K-carrageenan from a carrageenan mixture. In the method, the carrageenan mixture is used as the raw material, and 10 to 60% percent by volume of ethanol water solution of which the pH value is higher than 7 to 9 or higher than 8 to 9 is added to the raw material; the raw material and the ethanol water solution are filtered and dried after being refluxed at the temperature of 55 to 85DEG C for 0.5 to 2.5 hours or treated by ultrasonic waves of which the frequency is from 20 to 60KHz for 10 to 100 minutes; then, the K-carrageenan is obtained. The carrageenan prepared by the method of the present invention has high gel strength; medical capsules prepared from the carrageenan conform to the quality specification of the current Pharmacopoeia of People's Republic of China. The method has the advantages of brief technology, energy saving and cost reduction.

Description

A kind of preparation method of K-carrageenan

technical field

The invention relates to a method for separating and extracting carrageenan from seaweed, more specifically a method for preparing K-carrageenan from a carrageenan mixture.

Background technique

Polysaccharides are the most abundant biological macromolecules on earth, and carrageenan is an important member of the polysaccharide family. Carrageenan (Carrageenan), also known as carrageenan, is a β-D bonded by 1,3 -Sulfated cell wall polysaccharide formed by repeated cross-linking of galactosyl and 1,4-bonded α-D-galactosyl. It is extracted from various red algae such as Chondrus, Eucheuma, Gigartina and Hypena. These substances are rich in sources, non-polluting, and have many application fields. They were used more than 600 years ago, and they were studied in the 1950s. There are still many researchers conducting research in this area.

(1→3) and (1→4) cross-linked D-galactose is the common structure of carrageenan, which can be divided into many types due to different substituents. Carrageenan is divided into K group and λ group according to whether it contains 3,6-inner ether galactose and the content of sulfate group and the position of connection in the molecule. K-carrageenan (KC) is one of the K family, which is composed of β-(1→3)-D-galactose-4-sulfate group and α-(1→4)-3,6-inside ether Alternating copolymers of -D-galactose. Because of its unique properties such as excellent thermoreversible gelation, anti-protein coagulation, hydrophilic and non-toxic, it has become the leader in carrageenan and has attracted much attention. It is widely used in food, chemical and packaging. Especially in recent years, the application in the fields of medicine and bioengineering has aroused people's extensive research interest.

Different types of carrageenan have different uses due to their different properties. K-carrageenan has the best coagulation performance and low viscosity, which is suitable for making jelly, immobilized enzyme carrier, pharmaceutical capsule raw materials, etc.; λ-carrageenan has the highest viscosity, but cannot solidify, and is mainly used as a thickener; ι-carrageenan, whose viscosity is between K-carrageenan and λ-carrageenan, is usually used to react with protein and is suitable for making dairy products. K-carrageenan can form a hard gel, which meets the requirements of pharmaceutical excipients. In the pharmaceutical industry, it can also be used as an emulsifier, suspending agent, film-forming agent, gel agent, slow-release agent, etc., and has a wide range of uses.

There is no ideal repeating disaccharide-linked carrageenan in red algal phyllases, and it is a mixture of various carrageenan structures. Because K-carrageenan has good properties, especially its high gel strength, it is one of the raw materials for preparing pharmaceutical hard capsules. Therefore, the separation and preparation of K-carrageenan from carrageenan mixture has become the focus of researchers.

The Chinese Patent Document Patent No. 94112179.8 (Authorized Notification No. CN1037067C) reports a method for purifying K-carrageenan from a carrageenan mixture.

The preparation method is to use the kylin algae and the carrageenan semi-finished product as raw materials and use the sodium chloride aqueous solution as the leaching agent to leach the carrageenan mixture, and the conditions are as follows:

The concentration of sodium chloride is 0.6-1.0% (wt);

The pH value of the solution is 7.0-8.0;

Operating temperature 75-85°C;

Holding time 0.2-0.7hr;

Viscosity 35-45 centipoise;

filtering the leaching solution to remove impurities in the leaching solution to obtain a filtrate;

Potassium chloride is used as the salting-out agent to carry out salting-out precipitation to the filtrate, and its condition is:

The concentration of potassium chloride is 3.6-4.6% (wt);

Operating temperature 0-40°C;

Filter out the salt precipitation;

Using ethanol, isopropanol or their mixture as a water-squeezing agent to squeeze the filter cake, the condition is: water-squeezing agent (v):feeding amount (dry basis, wt)=3-8:1.

The K-carrageenan prepared by this patent method has a high gel strength, which can reach 800-1100g/cm ² , and the extraction rate of K-carrageenan is 75%. Potassium is used as a salting-out agent, and the generated K-carrageenan is the potassium salt of K-carrageenan. Because the potassium salt of K-carrageenan can only absorb water and swell in water, it is insoluble in water, and the sodium salt of λ-carrageenan, iota-carrageenan, and K-carrageenan can be dissolved in water. At the same time, the potassium salt of K-carrageenan should also be converted into the sodium salt of K-carrageenan. And its technological process is still long, and the cost is high.

Contents of the invention

The purpose of the present invention is to develop a new method for preparing K-carrageenan, overcome the deficiencies in the prior art, avoid generating the potassium salt of K-carrageenan, and make the produced K-carrageenan Has high gel strength.

In order to achieve the purpose of the invention, the researchers of the present invention have carried out a lot of research work. Algae was used as raw material, extracted with hot water, the hot water used was adjusted to PH5.0-6.5, and then water-miscible organic solvents such as methanol, ethanol, isopropanol, etc. were added to the resulting solution Precipitate K-carrageenan. The experimental results show that the gel strength of the obtained product is low, which may be due to the fact that K-carrageenan is prone to acid hydrolysis in acidic medium, heating makes the hydrolysis faster, the large molecules are degraded into small molecules, the viscosity decreases, and the gel strength decreases . In order to find out the cause of the decrease in gel strength, experiments were carried out by various methods. The results of many studies show that satisfactory results can be obtained under weak alkaline conditions. A preparation method of K-carrageenan has been studied, and the K-carrageenan gel prepared by this method has high gel strength.

Experiment shows that under weakly alkaline conditions, K-carrageenan has a solubility smaller than that of lambda-carrageenan and iota-carrageenan in the range of a certain concentration of ethanol. Utilize this property of K-carrageenan from carrageenan K-carrageenan was prepared from a mixture of gums.

A kind of preparation method of K-carrageenan of the present invention, take the mixture of carrageenan as raw material, add the ethanol aqueous solution of the concentration 10-60% volume percent of pH7.5～9 in the mixture of carrageenan, form mixture, at 55 Reflux at -85°C for 0.5-2.5 hours, place to room temperature, and filter to obtain K-carrageenan.

The raw material carrageenan mixture used is the carrageenan of commercially available food additive grade, and it is the mixture containing K-carrageenan, λ-carrageenan, and ι-carrageenan; - Carrageenan semi-finished carrageenan produced in the Philippines is used as a raw material.

In the mixture of raw carrageenan, the amount of the added ethanol aqueous solution with a concentration of 10-60% by volume at pH 7.5 to 9 is the amount of the mixture of raw carrageenan and the amount of 10-60% by volume at pH 7.5 to 9 The weight ratio is 1:0.5-6, preferably 1:1-6. The ethanol used can be technical grade ethanol, chemical pure ethanol, analytical pure ethanol, pharmaceutical grade ethanol. The pH value of the ethanol aqueous solution was adjusted with sodium hydroxide aqueous solution and hydrochloric acid. K-carrageenan can be produced by using ethanol aqueous solution with a pH of 7.5-8 and a concentration of 10-60% by volume. However, the gel strength of the K-carrageenan produced in this way is slightly lower than the gel strength produced by adding a pH 8.2-9 concentration of 10-60% ethanol aqueous solution. 10-60% by volume ethanol aqueous solution is preferred.

After adding 10-60% ethanol aqueous solution with pH 7.5-9 or 10-60% ethanol aqueous solution with pH 8.2-9, reflux at a temperature of 55-85°C, and the reflux temperature>85 °C degrades macromolecules into small molecules and reduces the gel strength, so the reflux temperature is preferably 60-80 °C. The time of reflux is 0.5-2.5 hours, preferably 1-2 hours.

Said room temperature is 15-25 ℃. When filtering, filter paper can be used in the laboratory, and a plate and frame filter press can be used in industry.

In order to reduce the impurity content of K-carrageenan after filtration, the ethanol aqueous solution of 10-60% volume percentage of pH7.5～9 or the ethanol of 10-60% volume percentage of pH8.2～9 can be used after filtration It is better to wash with aqueous solution 2-5 times.

In order to dry the filtered K-carrageenan, the filtered K-carrageenan or the filtered and washed K-carrageenan can be dried at a temperature of 45-85°C, and then dried at a temperature of 45-65°C For better, to the moisture content in K-carrageenan＜12% (percentage by weight).

In the experimental research, an accidental opportunity found that in the raw material carrageenan mixture, add ethanol aqueous solution with a concentration of 10-60% by volume at a pH of 7.5 to 9, and preferably add a concentration of 10-60 at a pH of 8.2 to 9. % volume percentage of ethanol aqueous solution, after ultrasonic treatment with an ultrasonic generator, K-carrageenan with better gel strength is prepared, forming another preparation method of K-carrageenan of the present invention.

The preparation method of another kind of K-carrageenan of the present invention, take the carrageenan mixture as raw material, add the ethanol aqueous solution of the concentration 10-60% volume percent of pH7.5～9 in raw material carrageenan mixture, form mixture, with frequency 20-60 kilohertz (KHz) ultrasonic treatment of the formed mixture for 10-100 minutes, during the ultrasonic treatment process, the temperature of the ultrasonic-treated mixture is controlled at 20-40 ° C, after ultrasonic treatment for 10-100 minutes, Filter to obtain K-carrageenan.

The raw carrageenan mixture used is also commercially available food additive grade carrageenan and semi-finished carrageenan produced in the Philippines.

In the mixture of raw material carrageenan, the amount of ethanol with a concentration of 10-60% volume percentage of pH 7.5～9 added is the amount of raw material carrageenan mixture and a concentration of 10-60% volume percentage of pH 7.5～9. The weight ratio is 1:0.5-6, preferably 1:1-6. The ethanol used can be technical grade ethanol, chemical pure ethanol, analytical pure ethanol, pharmaceutical grade ethanol. Sodium hydroxide aqueous solution and hydrochloric acid are used to adjust the pH value of ethanol aqueous solution, and K-carrageenan can be produced by using ethanol aqueous solution with a concentration of 10-60% volume percentage of pH 7.5-8. However, the gel strength of the K-carrageenan produced in this way is slightly lower than that of the K-carrageenan produced with a pH 8.2-9 concentration of 10-60% ethanol aqueous solution. It is preferably an aqueous ethanol solution with a concentration of 10-60% by volume at a pH of 8.2-9.

After adding 10-60% volume percent ethanol aqueous solution of pH 7.5～9 or adding 10-60% volume percent ethanol aqueous solution of pH 8.2～9, use 20-60 kilohertz (KHz) ultrasonic treatment 10-100 Minutes, preferably 10-60 minutes.

Said room temperature is 15-25 ℃. When filtering, filter paper can be used in the laboratory, and a plate and frame filter press can be used in industry.

In order to reduce the impurity content of K-carrageenan after filtration, it can be washed with 10-60% ethanol aqueous solution of pH 7.5～9 or with 10-60% ethanol aqueous solution of pH 8.2～9 2-5 times is better.

In order to dry the filtered K-carrageenan, the filtered K-carrageenan or the filtered and washed K-carrageenan can be dried at a temperature of 45-85°C, and then dried at a temperature of 45-65°C For better, to the moisture content in K-carrageenan＜12% (percentage by weight).

The K-carrageenan produced by the above two preparation methods of the present invention is also called seaweed polysaccharide gum, and the produced K-carrageenan is tested by the infrared spectroscopy method of the 26th edition of the United States Pharmacopoeia.

The excellent effect of the preparation method of K-carrageenan of the present invention is:

(1) The gel strength of the K-carrageenan prepared by the method of the present invention is high, some can be as high as 1100g/cm ² or more.

(2) the extraction rate of K-carrageenan can reach more than 80% with the method of the present invention, and said extraction rate is the ratio of the output of product and raw material amount, expresses with percentage.

(3) the kinematic viscosity of the K-carrageenan produced by the method of the present invention＞80mm ² /s (second) (measured with flat viscometer), its viscosity is generally between 80-110mm ² /s, with this The K-carrageenan prepared by the inventive method is used to prepare medicinal capsules which fully meet the quality requirements of the current Chinese Pharmacopoeia.

(4) The method technology of the present invention is brief, energy-conserving, does not need Potassium Chloride, does not form the potassium salt of carrageenan, reduces the cost of product.

Detailed ways

The method of the present invention is further described below with embodiment, contributes to the further understanding of K-carrageenan preparation method of the present invention, embodiment does not limit protection scope of the present invention, and its protection scope is determined by claims.

Example 1

Add 1 kilogram of commercially available food additive carrageenan mixture as raw material in the commercially available reflux tank (ZN type, produced by the pharmaceutical chemical container manufacturer), add the ethanol aqueous solution of the concentration 35% volume percentage of pH8.5 in the carrageenan mixture, form mixture. The weight ratio of the amount of raw material carrageenan to the amount of ethanol aqueous solution with a concentration of 35% volume percentage of pH8.5 is 1:2, reflux at a temperature of 80°C for 1.5 hours, place it at room temperature at 25°C, filter with filter paper, and filter with pH8 The ethanol aqueous solution of the concentration 35% volume percent of .5 is washed 3 times, and is dried to moisture content in the constant temperature box (DHP-420 type, Beijing Guangming Medical Instrument Factory) with commercially available laboratory at the temperature of 70 ℃ after washing. It is 11% by weight, and its extraction rate is 88% by weight. It passed the infrared spectrometry test described in the 26th edition of the United States Pharmacopoeia, and its gel strength was tested to be 1200g/cm ² , and its kinematic viscosity was 90mm ² /s (measured with a Pinnacle viscometer).

Example 2

Its used equipment and operation method thereof are basically the same as embodiment 1, only difference is, 1 kilogram of Philippines produces carrageenan semi-finished product, i.e. in the carrageenan mixture, adds the ethanol aqueous solution of the concentration 60% volume percent of pH9, forms mixture. The weight ratio of the amount of raw material to the amount of ethanol aqueous solution with a concentration of pH9 of 60% volume percentage is 1:6, reflux at a temperature of 55°C for 2.5 hours, place it at room temperature at 25°C, filter with filter paper, and then filter with a concentration of pH9 of 60%. The volume percent ethanol aqueous solution was washed 5 times, dried at a temperature of 85°C until the water content was 10% by weight, the extraction rate was 81% by weight, the gel strength was 1150g/cm ² , and the kinematic viscosity was 95mm ² /s (determined with Ping's viscometer).

Example 3

Its used equipment and operating method thereof are basically the same as in Example 1, only difference is, in the raw material carrageenan mixture, add the ethanol aqueous solution of the concentration 35% volume percent of pH7.5, the gel strength of gained product K-carrageenan It is 930g/cm ² .

Example 4

The equipment used and its operating method are basically the same as in Example 1, except that it is not washed after filtration, and the gel strength of its product K-carrageenan is 1050 g/cm ² .

Example 5

Its used equipment and operation method thereof are basically the same as in Example 1, only difference is that, with 1 kilogram of commercially available food additive grade carrageenan mixture as raw material, add the ethanol of the concentration 45% volume percent of pH8.2 in raw material aqueous solution to form a mixture. The weight ratio of the amount of raw material to the amount of ethanol aqueous solution with a concentration of 45% volume percentage of pH8.2 is 1:4, reflux at a temperature of 65°C for 1 hour, place it at room temperature at 15°C, filter with filter paper, and use pH8.2 Concentration of 45% volume percentage ethanol aqueous solution washed 3 times, dried at a temperature of 65°C until the water content was 11.5% by weight, the extraction rate was 85% by weight, the gel strength was 1180g/cm ² , and the kinematic viscosity It is 85mm ² /s (determined by Ping's viscometer).

Example 6

Its used equipment and operation method thereof are basically the same as in Example 1, only difference is, with 1 kilogram of commercially available food additive grade carrageenan mixture as raw material, add the ethanol of the concentration 25% volume percentage of pH8.7 in raw material aqueous solution to form a mixture. The weight ratio of the amount of raw material to the amount of ethanol aqueous solution with a concentration of 25% volume percentage of pH8.7 is 1:3, reflux at a temperature of 75°C for 0.8 hours, place it at room temperature at 25°C, filter with filter paper, and use pH8.7 Wash twice with an aqueous ethanol solution with a concentration of 25% by volume, dry at a temperature of 45°C until the water content is 10.5% by weight, the extraction rate is 81% by weight, the gel strength is 1200g/cm ² , and the kinematic viscosity It is 82mm ² /s (determined by Ping's viscometer).

Example 7

Its used equipment and operation method thereof are basically the same as embodiment 1, only difference is, with 1 kilogram of commercially available food additive grade carrageenan as raw material, add the ethanol aqueous solution of the concentration 10% volume percent of pH8.5 in raw material , forming a mixture. The weight ratio of raw material amount to 10% by volume ethanol aqueous solution at pH 8.5 is 1:0.5, and its gel strength is 1000 g/cm ² .

Example 8

A commercially available food additive grade carrageenan mixture is added in the container as a raw material, and an aqueous ethanol solution with a concentration of 35% by volume of pH 8.5 is added to the carrageenan mixture to form a mixture. The weight ratio of the ethanol aqueous solution amount of the concentration 35% volume percent of raw material amount and pH8.5 is 1: 2, with the mixture (ultrasonic generator is the JU-6212 type of JU-6212 type, Shanghai Produced by JP Ultrasound Equipment Co., Ltd.) 55 minutes. During the ultrasonic treatment process, the temperature of the ultrasonically treated mixture was controlled at 30°C. After ultrasonic treatment for 55 minutes, it was filtered with filter paper, washed 3 times with an aqueous ethanol solution with a concentration of 35% volume percentage of pH 8.5, and washed at 70°C. Under the temperature of ℃, it is 10.9% by weight to dry to moisture content with the constant temperature box that commercially available laboratory is used, and its extraction rate is 88.5% by weight, is qualified through the infrared spectrometry test described in 26th edition of United States Pharmacopoeia, after testing its condensation The glue strength is 1250g/cm ² , and its kinematic viscosity is 91mm ² /s (determined by Ping's viscometer).

Example 9

Its used equipment and operation method thereof are basically the same as embodiment 8, only difference is, 1 kilogram of Philippines produces carrageenan semi-finished product, i.e. in the carrageenan mixture, adds the ethanol aqueous solution of the concentration 60% volume percent of pH9, forms mixture. The weight ratio of raw material amount and the ethanol aqueous solution amount of the concentration 60% volume percent of pH9 is 1: 6, with the ultrasonic treatment of frequency 20 kilohertz (KHz) 100 minutes, the temperature of the mixture by ultrasonic treatment is controlled at 40 ℃, after ultrasonic treatment After processing for 100 minutes, filter with filter paper, wash 3 times with an aqueous ethanol solution with a concentration of 60% by volume of pH9, and dry at a temperature of 85° C. to a moisture content of 9.9% by weight after washing, and the extraction rate is 83% by weight , its gel strength is 1180g/cm ² , and its kinematic viscosity is 96mm ² /s (determined by Ping's viscometer).

Example 10

Its used equipment and operation method thereof are basically the same as embodiment 8, only difference is, in the raw material carrageenan mixture, add the ethanol aqueous solution of the concentration 35% volume percent of pH7.5, the gel strength of gained product K-carrageenan It is 950g/cm ² .

Example 11

The equipment used and its operating method are basically the same as in Example 8, except that it is not washed after filtration, and the gel strength of its product K-carrageenan is 1100 g/cm ² .

Example 12

Its used equipment and its operating method are basically the same as in Example 8, except that 1 kilogram of commercially available food additive grade carrageenan mixture is used as raw material, and ethanol with a concentration of 45% by volume of pH 8.2 is added to the raw material aqueous solution to form a mixture. The weight ratio of the ethanol aqueous solution amount of the concentration 45% volume percent of raw material amount and pH8.2 is 1: 4, with the ultrasonic treatment of frequency 60 kilohertz (KHz) 10 minutes, the temperature of the mixture of ultrasonic treatment is controlled at 20 ℃, After ultrasonic treatment for 10 minutes, filter with filter paper, wash 3 times with ethanol aqueous solution with a concentration of 45% by volume at pH 8.2, and dry at a temperature of 65°C until the moisture content is 11% by weight, and the extraction rate is 86.5%. Percentage by weight, its gel strength is 1200g/cm ² , and its kinematic viscosity is 87mm ² /s (measured by Ping's viscometer).

Example 13

The equipment used and its operation method are basically the same as in Example 8, except that 1 kg of commercially available food additive grade carrageenan mixture is used as raw material, and ethanol with a concentration of 25% by volume of pH 8.7 is added to the raw material aqueous solution to form a mixture. The weight ratio of the ethanol aqueous solution amount of the concentration 25% volume percentage of raw material amount and pH8.7 is 1: 3, with the ultrasonic treatment of frequency 30 kilohertz (KHz) 20 minutes, the temperature of the mixture by ultrasonic treatment is controlled at 30 ℃, After ultrasonic treatment for 20 minutes, filter with filter paper, wash twice with ethanol aqueous solution with a concentration of 25% by volume at pH 8.7, and dry at a temperature of 45°C until the moisture content is 10.1% by weight, and the extraction rate is 82%. Percentage by weight, its gel strength is 1210g/cm ² , and its kinematic viscosity is 83mm ² /s (measured by Ping's viscometer).

Example 14

Its used equipment and operation method thereof are basically the same as embodiment 8, only difference is, with 1 kilogram of commercially available food additive grade carrageenan as raw material, add the ethanol aqueous solution of the concentration 10% volume percent of pH8.5 in the raw material, A mixture is formed. The weight ratio of raw material amount to 10% by volume ethanol aqueous solution at pH 8.5 is 1:0.5, and its gel strength is 1050 g/cm ² .

Claims (18)

1, a kind of preparation method of K-carrageenan, it is characterized in that, take the mixture of carrageenan as raw material, add the concentration of pH7.5～9 in the mixture of carrageenan and be the aqueous ethanol solution of 10-60% volume percent, form The mixture is refluxed for 0.5-2.5 hours at a temperature of 55-85° C., left to room temperature, and filtered to obtain K-carrageenan. This method does not form potassium salt of K-carrageenan. 2, according to the preparation method of a kind of K-carrageenan of claim 1, it is characterized in that, the amount of raw material carrageenan mixture and the concentration of pH7.5～9 are the weight ratio of the ethanol aqueous solution amount of 10-60% volume percent: 1: 0.5~6. 3, according to the preparation method of a kind of K-carrageenan of claim 2, it is characterized in that, the amount of raw material carrageenan mixture and the concentration of pH7.5～9 are the weight ratio of the ethanol aqueous solution amount of 10-60% volume percent: 1:1~6. 4, according to the preparation method of a kind of K-carrageenan of claim 1, it is characterized in that, the amount of raw material carrageenan mixture and the concentration of pH8.2～9 are the weight ratio of the ethanol aqueous solution amount of 10-60% volume percent: 1: 0.5~6. 5, according to the preparation method of a kind of K-carrageenan of claim 4, it is characterized in that, the amount of raw material carrageenan mixture and the concentration of pH 8.2～9 are that the weight ratio of the ethanol aqueous solution amount of 10-60% volume percent is 1 : 1~6. 6. A preparation method of K-carrageenan according to claim 1, characterized in that it is refluxed at a temperature of 60-80°C for 1-2 hours. 7. A preparation method of K-carrageenan according to claim 1, characterized in that, after filtration, use 10-60% ethanol aqueous solution with pH 7.5-9 or 10- Wash with 60% ethanol aqueous solution for 2-5 times. 8, according to the preparation method of a kind of K-carrageenan of claim 1, it is characterized in that, filter or the K-carrageenan after filter washing is dried at the temperature of 45-85 ℃ to the moisture content in K-carrageenan <12% by weight. 9. A method for preparing K-carrageenan according to claim 8, characterized in that it is dried at a temperature of 45-65°C. 10. A method for preparing K-carrageenan, which is characterized in that, using a mixture of carrageenan as a raw material, adding an aqueous ethanol solution with a pH of 7.5 to 9 and a concentration of 10-60% by volume, Form a mixture, and treat the formed mixture with an ultrasonic wave with a frequency of 20-60 kHz for 10-100 minutes. During the ultrasonic treatment, the temperature of the treated mixture is controlled at 20-40 ° C. After ultrasonic treatment for 10-100 minutes , filtered to get K-carrageenan, this method does not form the potassium salt of K-carrageenan. 11, according to the preparation method of a kind of K-carrageenan of claim 10, it is characterized in that, the amount of raw material carrageenan mixture and the concentration of pH7.5～9 are the weight ratio of the ethanol aqueous solution amount of 10-60% volume percent: 1: 0.5~6. 12. A method for preparing K-carrageenan according to claim 11, characterized in that the weight ratio of the amount of raw material carrageenan mixture to the amount of ethanol aqueous solution with a concentration of 10-60% by volume at pH 7.5 to 9 is 1:1~6. 13. The preparation method of a kind of K-carrageenan according to claim 10, characterized in that, the weight ratio of the amount of raw material carrageenan mixture to the amount of ethanol aqueous solution with a concentration of 10-60% by volume at pH 8.2 to 9 is 1: 0.5~6. 14, according to the preparation method of a kind of K-carrageenan of claim 13, it is characterized in that, the weight ratio of the amount of raw material carrageenan mixture and the concentration of pH8. 1:1~6. 15. A method for preparing K-carrageenan according to claim 10, characterized in that the resulting mixture is treated with ultrasonic waves at a frequency of 20-60 kHz for 10-60 minutes. 16. A method for preparing K-carrageenan according to claim 10, characterized in that, after filtration, use 10-60% ethanol aqueous solution with pH 7.5-9 or 10- Wash with 60% ethanol aqueous solution for 2-5 times. 17. A method for preparing K-carrageenan according to claim 10, characterized in that the filtered or filtered carrageenan is dried at a temperature of 45-85°C until the moisture content in K-carrageenan is <12% % by weight. 18. A method for preparing K-carrageenan according to claim 17, characterized in that it is dried at a temperature of 45-65°C.