Extraction method and device for improving stability of purple pigment of purple blue grass

Abstract

The invention discloses an extraction method and device for improving stability of purple pigment of purple blue grass, and the method comprises the following steps: putting the purple blue grass into a stainless steel barrel capable of being vacuumized, firstly vacuumizing, then introducing hot water added with amino acid and an antioxidant for extraction, and finally adding sodium chloride into the obtained extract liquid to obtain the purple pigment of the purple blue grass. And carrying out rotary evaporation concentration on the obtained leaching solution, and freeze-drying the concentrated solution to obtain purple blue grass purple pigment powder. According to the method disclosed by the invention, a mode of extracting by heating water after vacuumizing is adopted, and amino acid, an antioxidant and the like are added in the process of extracting the purpurin, so that the stability and the extraction rate of the pigment are greatly improved. The method has the advantages that the process is simple and easy to implement, the adopted device is simple, the cost is low, the pigment extraction rate is high, and the purple pigment extracted by the method and the device is good in color development effect, good in oxidation resistance and high in stability.

Description

Technical Field

[0001] The invention relates to the technical field of natural pigment extraction, and in particular to an extraction method and a device for improving the stability of purple pigment of violet bluegrass. Background Art

[0002] Pigments play an important role in food processing and other links. Currently, a large number of edible pigments are used in food additives, which can be divided into two categories: natural pigments and artificial synthetic pigments. Synthetic pigments have the advantages of bright color, strong tinting power, high fastness, stable properties and low cost. However, most synthetic pigments are harmful to the human body and have low safety. Natural pigments refer to pigments obtained from natural resources, mainly pigments extracted from animals, plants or microorganisms. Natural pigments have the advantages of high safety and natural color. They also have certain nutritional effects and pharmacological effects. They have gradually replaced synthetic pigments and become an important part of food additives. With the continuous improvement of people's living standards, environmental protection and health awareness are increasing, and the application of natural pigments with both dyeing functions and health care effects in the food industry has received more and more attention.

[0003] Peristrophe roxburghiana is a plant of the Acanthaceae family. It is mainly distributed in Yunnan, Guangdong, Guangxi and other places in my country. It is also called red blue grass, red orchid grass, purple blue vine, red silk thread, etc. It is sweet, light and cool in nature, with a light fragrance. Peristrophe roxburghiana contains a variety of compounds such as alkaloids, flavonoids, terpenes, steroids and glycosides, phenylpropanoids and volatile oils. It is used in traditional Chinese medicine for anti-inflammatory, heat-clearing and detoxification, diuresis, lung heat-clearing, cough-relieving, blood stasis-dispersing, blood-cooling and hemostasis, swelling and pain relief, etc. The whole plant can be used as medicine. The purple pigment of purple blue grass can be used as a natural edible pigment. It has the advantages of being non-toxic, having no side effects and high safety. It plays an important role in preventing cancer, lowering blood pressure, lowering blood lipids, protecting eyesight, etc., and is very popular with consumers. Peristrophe roxburghiana is one of the raw materials for the traditional five-color glutinous rice of the Zhuang nationality in Guangxi. After soaking, purple juice is obtained, which is used to make purple glutinous rice. Purple glutinous rice is loved by people because of its fragrance of purple blue grass and bright purple color. The purple pigment in indigo plant, as a natural dye, has great application prospects in food coloring.

[0004] Natural pigments extracted from plants are safe and non-toxic, retaining the rich nutrients and medicinal ingredients in the plants. However, the application of natural pigments is restricted by their poor stability, easy oxidation, weak coloring, and other shortcomings. In the study of natural edible pigments, the extraction process and pigment stability are more critical. However, the current domestic research on purple blue grass is mostly focused on component analysis and pharmacological activity research, and there are few reports on the extraction process of purple blue grass purple pigment and how to improve its stability. Therefore, studying an extraction method to improve the stability of purple blue grass purple pigment is of great significance for the further development and application of purple blue grass purple pigment. Summary of the invention

[0005] The purpose of the present invention is to provide an extraction method and a device for improving the stability of purple pigment of indigofera indigofera in view of the deficiencies in the prior art. The method adopts a method of vacuumizing and then heating water for extraction, and in the process of extracting the purple pigment, amino acids and antioxidants are added to greatly improve the stability and extraction rate of the pigment. The purple pigment of indigofera indigofera extracted by the method and the device has good color development effect, high stability and high extraction rate.

[0006] The technical solution adopted by the present invention is as follows: A method for extracting purple pigment from bluegrass to improve its stability comprises the following steps: (1) After harvesting, wash the purple indigo grass, cut it into 4-6 cm lengths, and put it into container A. Container A is a vacuum-evacuable stainless steel barrel with a sandwich wall that can be cooled with water or heated with steam. It has an insulation layer on the outside and a sealable stainless steel cover on the top. There is a pipe on the cover that connects to a vacuum pump, and a valve I is installed on the pipe. An air inlet valve III is left on the cover. There is a pipe at the bottom of the container that connects to container B, and a valve II is installed on the pipe. (2) Container B is a stainless steel interlayer heating pot, with a pipe at the bottom of the pot connected to container A, and controlled by valve II in the middle. The heating method is electric heating, interlayer steam heating or steam directly heating the liquid in the pot; (3) After the cut purple blue grass is put into container A, cover the lid, close valve II, open vacuum valve I, and use a vacuum pump to evacuate container A. After the vacuum degree reaches -0.07Mpa, keep it for at least 10 minutes; while evacuating, add water to container B, and heat the water to above 95°C, add arginine, tyrosine, histidine, serine and lysine, so that the final concentration of each amino acid reaches 0.01% to 0.2%; add antioxidants, so that the final concentration of antioxidants reaches 0.01% to 0.05%; (4) Turn off the vacuum pump of container A, close the vacuum valve I, and open the pipeline valve II. At this time, the hot water in container B enters container A through the pipeline. According to the material-liquid ratio of 1: 5-8 g / mL, when the required hot water volume in container A is reached, close the pipeline valve II. After keeping warm for 1 hour, pass tap water into the interlayer of container A for cooling, or naturally cool the tank to room temperature; open the air inlet valve of container A, balance the air pressure, open the lid, and use a water pump to filter out the extract; (5) Sodium chloride is added to the obtained extract and mixed to make the mass percentage concentration of sodium chloride reach 1% to 2%, and then the obtained extract is concentrated by rotary evaporation at 35°C, and the concentrated solution is freeze-dried to obtain purple pigment powder of indigo plant.

[0007] Furthermore, in the above-mentioned extraction method for improving the stability of purple pigment of indigo plant, the antioxidant added in step (3) is apple polyphenol.

[0008] Furthermore, the extraction method for improving the stability of purple pigment of indigo plant adopts the following device to extract purple pigment of indigo plant, and the device comprises: container A, container B and vacuum pump, container A is a stainless steel barrel that can be evacuated, the barrel wall is a hollow interlayer, the interlayer is provided with a steam or cooling water inlet, which can be connected to water for cooling or steam for heating, there is an insulation layer on the outside, a sealable stainless steel cover is provided on the upper part, a pipe is provided on the cover to connect the vacuum pump, a valve I is installed on the pipe, and an air inlet valve III is left on the cover; a pipe is provided at the bottom of container A to connect container B, a valve II is installed on the pipe, container B is a stainless steel interlayer heating pot, the pot wall is provided with a hollow interlayer, the interlayer is provided with a steam or cooling water inlet, and container B is heated by electric heating, interlayer steam heating or steam directly heating the liquid in the pot.

[0009] The beneficial effects of the present invention are: 1. During the extraction process of purple pigment of violet grass, the solution reacts with oxygen, causing the purple color to turn into purple-red. The present invention has shown through research that adding amino acids during the extraction process can delay this process. The present invention adds arginine, tyrosine, histidine, serine and lysine during the extraction process to protect the pigment and improve the stability and extraction rate of the pigment.

[0010] 2. The present invention adds an antioxidant, apple polyphenol, during the extraction process of purple pigment of violet blue grass. Apple polyphenol is a pure natural antioxidant extracted from apples, which has the functions of scavenging free radicals, anti-oxidation, deodorization, freshness preservation, fragrance preservation, color protection, prevention of vitamin loss, anti-allergy, anti-virus, etc. The antioxidant capacity of apple polyphenol is stronger than that of tea polyphenol, and its antioxidant capacity is 10 to 30 times that of vitamin E. Apple polyphenol can be obtained commercially. Adding apple polyphenol in the present invention can play an antioxidant role, thereby protecting the extracted purple pigment from oxidation, and improving the antioxidant and stability of the extracted purple pigment.

[0011] 3. In the present invention, sodium chloride is added to the extracted leaching solution and mixed evenly, which can play a certain role in color enhancement and color protection, and can further improve the stability of the extracted purple pigment.

[0012] 4. The present invention discloses an extraction method and device for improving the stability of purple pigment of violet grass, which adopts the method of vacuumizing and then heating water extraction, and in the process of extracting purple pigment, amino acids and antioxidants are added, which can greatly improve the stability and extraction rate of purple pigment of violet grass. Moreover, the purple pigment solution obtained by extracting using the device of the present invention has a good purple coloring effect. The method is simple and easy to operate, the device and equipment used are simple, the cost is low, and the pigment extraction rate is high. Experiments have shown that the method and device of the present invention can effectively improve the stability of the extracted purple pigment, and the extracted purple pigment of violet grass has a good coloring effect, good antioxidant properties, and high stability. The present invention can provide a basis for further development and utilization of purple pigment of violet grass. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention is a schematic diagram of the connection structure of a device used in a method for extracting purple pigment of blue grass for improving stability; the numbers and names in the figure are as follows: 1. container A, 2. container B, 3. vacuum pump, 4. interlayer, 5. steam or cooling water inlet, 6. valve I, 7. valve II.

[0014] Figure 2 The solution obtained by boiling purple indigo grass cut into different lengths.

[0015] Figure 3 The purple blue grass solution is obtained by boiling in a conventional pot and extracting using the method of the device of the present invention.

[0016] Figure 4 Heating stability comparison test results. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the examples and drawings. The methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are all commercially available unless otherwise specified. Example 1

[0018] A method for extracting purple pigment from bluegrass to improve its stability comprises the following steps: (1) After harvesting, wash the purple indigo grass, cut it into 4-6 cm lengths, and put it into container A. Container A is a vacuum-evacuable stainless steel barrel with a sandwich wall that can be cooled with water or heated with steam. It has an insulation layer on the outside and a sealable stainless steel cover on the top. There is a pipe on the cover that connects to a vacuum pump, and a valve I is installed on the pipe. An air inlet valve III is left on the cover. There is a pipe at the bottom of the container that connects to container B, and a valve II is installed on the pipe. (2) Container B is a stainless steel interlayer heating pot, with a pipe at the bottom of the pot connected to container A, and controlled by valve II in the middle. The heating method is electric heating, interlayer steam heating or steam directly heating the liquid in the pot; (3) After the cut purple blue grass is put into container A, cover the lid, close valve II, open vacuum valve I, and use a vacuum pump to evacuate container A. After the vacuum degree reaches -0.07Mpa, keep it for 10 minutes; while evacuating, add water to container B, and heat the water to above 95°C, add arginine, tyrosine, histidine, serine and lysine, so that the final concentration of each amino acid reaches 0.06%; add apple polyphenols, so that the final concentration of apple polyphenols reaches 0.02%; (4) Turn off the vacuum pump of container A, close the vacuum valve I, and open the pipeline valve II. At this time, the hot water in container B enters container A through the pipeline. According to the material-liquid ratio of 1:6 g / mL, when the required hot water volume in container A is reached, close the pipeline valve II. After keeping warm for 1 hour, pass tap water into the interlayer of container A to cool it to room temperature; open the air inlet valve of container A, balance the air pressure, open the lid, and use a water pump to filter out the extract; (5) Sodium chloride is added to the obtained extract and mixed to make the mass percentage concentration of sodium chloride reach 1%, and then the obtained extract is concentrated by rotary evaporation at 35° C., and the concentrated solution is freeze-dried to obtain purple pigment powder of indigo plant. Example 2

[0019] A method for extracting purple pigment from bluegrass to improve its stability comprises the following steps: (1) After harvesting, wash the purple indigo grass, cut it into 4-6 cm lengths, and put it into container A. Container A is a vacuum-evacuable stainless steel barrel with a sandwich wall that can be cooled with water or heated with steam. It has an insulation layer on the outside and a sealable stainless steel cover on the top. There is a pipe on the cover that connects to a vacuum pump, and a valve I is installed on the pipe. An air inlet valve III is left on the cover. There is a pipe at the bottom of the container that connects to container B, and a valve II is installed on the pipe. (2) Container B is a stainless steel interlayer heating pot, with a pipe at the bottom of the pot connected to container A, and controlled by valve II in the middle. The heating method is electric heating, interlayer steam heating or steam directly heating the liquid in the pot; (3) After the cut purple blue grass is put into container A, cover the lid, close valve II, open vacuum valve I, and use a vacuum pump to evacuate container A. After the vacuum degree reaches -0.07Mpa, keep it for 15 minutes; while evacuating, add water to container B and heat the water to 98°C, add arginine, tyrosine, histidine, serine and lysine to make the final concentration of each amino acid reach 0.08%; add apple polyphenols to make the final concentration of apple polyphenols reach 0.03%; (4) Turn off the vacuum pump of container A, close the vacuum valve I, and open the pipeline valve II. At this time, the hot water in container B enters container A through the pipeline. According to the ratio of material to liquid of 1:5g / mL, when the required volume of hot water in container A is reached, close the pipeline valve II. After keeping warm for 1 hour, pass tap water into the interlayer of container A to cool it to room temperature; open the air inlet valve of container A, balance the air pressure, open the lid, and use a water pump to filter out the extract; (5) Sodium chloride is added to the obtained extract and mixed to make the mass percentage concentration of sodium chloride reach 1.5%, and then the obtained extract is concentrated by rotary evaporation at 35° C., and the concentrated solution is freeze-dried to obtain purple pigment powder of indigo plant. Example 3

[0020] A method for extracting purple pigment from bluegrass to improve its stability comprises the following steps: (1) After harvesting, wash the purple indigo grass, cut it into 4-6 cm lengths, and put it into container A. Container A is a vacuum-evacuable stainless steel barrel with a sandwich wall that can be cooled with water or heated with steam. It has an insulation layer on the outside and a sealable stainless steel cover on the top. There is a pipe on the cover that connects to a vacuum pump, and a valve I is installed on the pipe. An air inlet valve III is left on the cover. There is a pipe at the bottom of the container that connects to container B, and a valve II is installed on the pipe. (2) Container B is a stainless steel interlayer heating pot, with a pipe at the bottom of the pot connected to container A, and controlled by valve II in the middle. The heating method is electric heating, interlayer steam heating or steam directly heating the liquid in the pot; (3) After the cut purple blue grass is put into container A, cover the lid, close valve II, open vacuum valve I, and use a vacuum pump to evacuate container A. After the vacuum degree reaches -0.07Mpa, keep it for 25 minutes; while evacuating, add water to container B, and heat the water to above 95°C, add arginine, tyrosine, histidine, serine and lysine, so that the final concentration of arginine and tyrosine reaches 0.07%, the final concentration of histidine and serine reaches 0.04%, and the final concentration of lysine reaches 0.12%; add apple polyphenols, so that the final concentration of apple polyphenols reaches 0.01%; (4) Turn off the vacuum pump of container A, close the vacuum valve I, and open the pipeline valve II. At this time, the hot water in container B enters container A through the pipeline. According to the ratio of material to liquid of 1:7g / mL, when the required volume of hot water is reached in container A, close the pipeline valve II. After keeping warm for 1 hour, pass tap water into the interlayer of container A for cooling, or cool the tank naturally to room temperature; open the air inlet valve of container A, balance the air pressure, open the lid, and use a water pump to filter out the extract; (5) Sodium chloride is added to the obtained extract and mixed to make the mass percentage concentration of sodium chloride reach 2%, and then the obtained extract is concentrated by rotary evaporation at 35°C, and the concentrated solution is freeze-dried to obtain purple pigment powder of indigo plant. Example 4

[0021] A method for extracting purple pigment from bluegrass to improve its stability comprises the following steps: (1) After harvesting, wash the purple indigo grass, cut it into 4-6 cm lengths, and put it into container A. Container A is a vacuum-evacuable stainless steel barrel with a sandwich wall that can be cooled with water or heated with steam. It has an insulation layer on the outside and a sealable stainless steel cover on the top. There is a pipe on the cover that connects to a vacuum pump, and a valve I is installed on the pipe. An air inlet valve III is left on the cover. There is a pipe at the bottom of the container that connects to container B, and a valve II is installed on the pipe. (2) Container B is a stainless steel interlayer heating pot, with a pipe at the bottom of the pot connected to container A, and controlled by valve II in the middle. The heating method is electric heating, interlayer steam heating or steam directly heating the liquid in the pot; (3) After the cut purple blue grass is put into container A, cover the lid, close valve II, open vacuum valve I, and use a vacuum pump to evacuate container A. After reaching a vacuum degree of -0.07Mpa, keep it for 20 minutes; while evacuating, add water to container B, and heat the water to above 95°C, add arginine, tyrosine, histidine, serine and lysine, so that the final concentration of arginine reaches 0.1%, the final concentration of tyrosine reaches 0.05%, the final concentration of histidine reaches 0.02%, the final concentration of serine reaches 0.11%, and the final concentration of lysine reaches 0.2%; add apple polyphenols, so that the final concentration of apple polyphenols reaches 0.04%; (4) Turn off the vacuum pump of container A, close the vacuum valve I, and open the pipeline valve II. At this time, the hot water in container B enters container A through the pipeline. According to the material-liquid ratio of 1:8g / mL, when the required hot water volume in container A is reached, close the pipeline valve II. After keeping warm for 1 hour, pass tap water into the interlayer of container A for cooling, or naturally cool the tank to room temperature; open the air inlet valve of container A, balance the air pressure, open the lid, and use a water pump to filter out the extract; (5) Sodium chloride is added to the obtained extract and mixed to make the mass percentage concentration of sodium chloride reach 1.6%, and then the obtained extract is concentrated by rotary evaporation at 35° C., and the concentrated solution is freeze-dried to obtain purple pigment powder of indigo plant.

[0022] A schematic diagram of the connection structure of the device used in the method for extracting purple pigment of high-stability violet grass of the present invention; Figure 1 As shown, from Figure 1It can be seen that the device includes: container A1, container B2 and vacuum pump 3. Container A1 is a stainless steel barrel that can be evacuated. The barrel wall is a hollow interlayer 4. The interlayer is provided with a steam or cooling water inlet 5, which can be connected to water for cooling or steam for heating. There is a thermal insulation layer on the outside and a sealable stainless steel cover on the top. The cover is provided with a pipe connected to the vacuum pump 3, and a valve I6 is installed on the pipe. The cover is left with an air inlet valve III; the bottom of container A1 is provided with a pipe connected to container B2, and a valve II7 is installed on the pipe. Container B2 is a stainless steel interlayer heating pot. The pot wall is provided with a hollow interlayer 4, and the interlayer is provided with a steam or cooling water inlet 5. The heating method of container B is electric heating, interlayer steam heating or steam directly heating the liquid in the pot.

[0023] Example 5 Test 1. Comparison of boiling solutions with different cutting lengths Method: Cut the purple blue grass into different lengths: chop less than 1 cm, chop to 1-3 cm, chop to 4-6 cm, chop to 7-10 cm, then add equal amounts of water, boil for the same time, and filter the solution to clarify. Figure 2 The photos show that when the purple blue grass is chopped into pieces less than 1 cm, it is easily oxidized and the color becomes red; the color of 4-6 cm is the best. Therefore, the extraction method of the present invention stipulates that the purple blue grass is harvested, washed, and cut into 4-6 cm lengths.

[0024] 2. Comparison of conventional boiling extraction and extraction using the device of the present invention Conventional method: Cut the purple blue grass into 4-6 cm lengths, put it into a stainless steel pot, add 5 times the weight of the grass in water, boil it for 15 minutes and then cool it down.

[0025] The device of the present invention is used as follows: after chopped into 4-6 cm length, put into container A, vacuum is firstly drawn to a vacuum degree of -0.07 Mpa, and then maintained for 10 minutes; then 5 times the weight of 95°C hot water is poured in, and the extraction is performed after the heat is kept for 1 hour.

[0026] The purple blue grass solution obtained by boiling in a conventional pot and using the method of the device of the present invention is shown in FIG. Figure 3 .Depend on Figure 3 It can be seen that by using the device and method of the present invention, the color of the obtained purple indigo grass solution appears darker purple and has a good color development effect.

[0027] 3. Stability test The device of the present invention was used for extraction, and various amino acids, apple polyphenols and sodium chloride were added during the extraction process according to the extraction method described in Example 2 to obtain an extract; the extract was compared with the solution obtained by conventional boiling in a stainless steel pot. Since the solution obtained by the device and method of the present invention is darker purple, it was diluted with water, and the characteristic peak 585nm reported by the violet grass pigment was used as a reference. After dilution until the absorbance values ​​of the two at 585nm were the same, it was placed in a test tube with a lid, and placed in a water bath at 70°C. The spectral curves were measured on the 0th day, the 10th day, and the 30th day, respectively. The experimental results are shown in Figure 4 .Depend on Figure 4 The spectral curve shows that on the 10th day of water bathing, the curve of the lithospermum solution obtained by conventional boiling extraction has been deformed, the characteristic absorbance value at 585nm is lower than that of the method of the present invention, and the absorbance value at 400-500nm becomes higher. On the 30th day, the spectral curve of the solution extracted by boiling extraction has no peaks and valleys at all, while the curve of the solution extracted by the method of the present invention still retains the characteristic peaks and valleys. It shows that the lithospermum pigment extracted by the method of the present invention has good stability, and the method and device of the present invention can effectively improve the stability of the extracted purple pigment of lithospermum.

Claims

1. A method for extracting purple pigment from violet grass to improve its stability, characterized in that: The following steps are involved: (1) After harvesting, wash the purple indigo grass, cut it into 4-6 cm lengths, and put it into container A. Container A is a vacuum-evacuable stainless steel barrel with a sandwich wall that can be cooled with water or heated with steam. It has an insulation layer on the outside and a sealable stainless steel cover on the top. There is a pipe on the cover that connects to a vacuum pump, and a valve I is installed on the pipe. An air inlet valve III is left on the cover. There is a pipe at the bottom of the container that connects to container B, and a valve II is installed on the pipe. (2) Container B is a stainless steel interlayer heating pot, with a pipe at the bottom of the pot connected to container A, and controlled by valve II in the middle. The heating method is electric heating, interlayer steam heating or steam directly heating the liquid in the pot; (3) After the cut purple blue grass is put into container A, cover the lid, close valve II, open vacuum valve I, and use a vacuum pump to evacuate container A. After the vacuum degree reaches -0.07Mpa, keep it for at least 10 minutes; while evacuating, add water to container B, and heat the water to above 95°C, add arginine, tyrosine, histidine, serine and lysine, so that the final concentration of each amino acid reaches 0.01% to 0.2%; add antioxidants, so that the final concentration of antioxidants reaches 0.01% to 0.05%; (4) Turn off the vacuum pump of container A, close the vacuum valve I, and open the pipeline valve II. At this time, the hot water in container B enters container A through the pipeline. According to the material-liquid ratio of 1: 5-8 g / mL, when the required hot water volume in container A is reached, close the pipeline valve II. After keeping warm for 1 hour, pass tap water into the interlayer of container A for cooling, or naturally cool the tank to room temperature; open the air inlet valve of container A, balance the air pressure, open the lid, and use a water pump to filter out the extract; (5) Sodium chloride is added to the obtained extract and mixed to make the mass percentage concentration of sodium chloride reach 1% to 2%, and then the obtained extract is concentrated by rotary evaporation at 35°C, and the concentrated solution is freeze-dried to obtain purple pigment powder of indigo plant.

2. The method for extracting the purple pigment from bluegrass for improving stability according to claim 1, wherein: The antioxidant added in step (3) is apple polyphenol.

3. The method for extracting the purple pigment from bluegrass for improving stability as claimed in claim 1, characterized in that: The following device is used to extract purple pigment from violet grass, the device comprising: a container A (1), a container B (2) and a vacuum pump (3), wherein the container A (1) is a stainless steel barrel that can be evacuated, the barrel wall is a hollow interlayer (4), the interlayer is provided with a steam or cooling water inlet (5), the outside is provided with a heat-insulating layer, the upper part is provided with a sealable stainless steel cover, the cover is provided with a pipe connected to the vacuum pump (3), the pipe is provided with a valve I (6), and the cover is provided with an air inlet valve III; the bottom of the container A (1) is provided with a pipe connected to the container B (2), the pipe is provided with a valve II (7), and the container B (2) is a stainless steel interlayer heating pot, the pot wall is provided with a hollow interlayer (4), and the interlayer is provided with a steam or cooling water inlet (5).

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