Method for extracting pepper essential oil and pepper essential oil obtained therefrom

Abstract

The present invention relates to the technical field of natural product extraction, and in particular to a method for extracting pepper essential oil and the pepper essential oil obtained therefrom. The present invention provides a method for extracting pepper essential oil, the method comprising: subjecting a pepper raw material to subcritical extraction to obtain pepper oil, subjecting the pepper oil to molecular distillation, and collecting a light phase. The method can ensure a high extraction yield of pepper essential oil while ensuring that less piperine is extracted and reducing the loss of piperine, thereby significantly increasing the content of piperine in the pepper raw material after essential oil extraction; the extraction method can also effectively remove pesticide residues in the pepper raw material, ensuring low pesticide residues in the pepper raw material after pepper essential oil extraction. In addition, the method is easy to operate and can be industrialized for production.

Description

Technical Field

[0001] The invention relates to the technical field of natural product extraction, in particular to a method for extracting pepper essential oil and the prepared pepper essential oil. Background Art

[0002] Pepper, especially black pepper, is rich in volatile oils and flavor components such as piperine, and is currently a widely used spice. Pepper essential oil is the component that provides the characteristic aroma of pepper, and has the characteristic aroma of pepper. Piperine is the component that provides the spicy taste of pepper. Both are widely used in many fields such as food, perfume, and physical therapy.

[0003] The traditional production method of pepper essential oil is steam distillation or supercritical extraction. Steam distillation is to pass high-temperature steam through the crushed pepper raw material, so that the essential oil is carried out by the steam, and then condensed into liquid, and then separated from water to obtain pepper essential oil. This method not only consumes a large amount of steam, resulting in high energy consumption, but also in the process of steam distillation, due to the high temperature, the effective ingredient piperine in the pepper raw material is lost by 10-20%, affecting the quality of the subsequent extracted pepper oleoresin.

[0004] The supercritical extraction method is to crush the pepper raw material and then use supercritical carbon dioxide to extract it. The extract is evaporated to obtain supercritical pepper oil. The pepper oil obtained by this method contains about 10-15% piperine, which greatly reduces the content of piperine in the pepper raw material after extraction, affecting the product quality of the subsequent extracted pepper oleoresin.

[0005] Patent application CN107927696A uses supercritical carbon dioxide to extract crushed pepper raw materials, which are stirred and allowed to stand for separation into three layers, wherein the upper layer of light yellow transparent clear liquid and the middle layer of yellow semi-solid product are filtered to obtain a filtrate, the filtrate is mixed to obtain pepper essential oil, and the yellow solid obtained by filtration is pepper oleoresin. It can be seen that piperine is extracted during the extraction process of the above method, resulting in a decrease in the quality of the pepper raw material after the essential oil is extracted.

[0006] In summary, it is necessary to develop an extraction method that can reduce piperine loss and ensure high piperine content in pepper raw materials after essential oil extraction. Summary of the invention

[0007] The invention aims to provide a method for extracting pepper essential oil and the prepared pepper essential oil.

[0008] The present invention aims to reduce the loss of piperine in the process of extracting pepper essential oil and reduce the content of piperine extracted in the process of extracting essential oil, and develops a method for extracting pepper essential oil. The main active ingredients in pepper raw materials are pepper essential oil and piperine. The thermal stability of piperine is poor, and more losses will occur at high temperatures, resulting in a decrease in the product quality of pepper resin after essential oil extraction, and subsequent processed products do not meet the standards. In addition, pepper raw materials usually contain high pesticide residues. Therefore, the pesticide residues in the pepper raw materials need to be removed as much as possible during the process of extracting pepper essential oil. The present invention has found in the research and development process that it is difficult to simultaneously ensure a high essential oil yield and a low piperine loss and a high piperine retention rate and low pesticide residues in the pepper raw materials after essential oil extraction. The present invention has obtained the extraction method of the present invention by making many attempts to the pepper essential oil extraction method.

[0009] Specifically, the present invention provides the following technical solutions:

[0010] The invention provides a method for extracting pepper essential oil. The method comprises: performing subcritical extraction on a pepper raw material to obtain pepper oil, performing molecular distillation on the pepper oil, and collecting a light phase.

[0011] The present invention finds that, compared with other extraction methods, the method of using subcritical extraction combined with molecular distillation is more conducive to reducing the loss of piperine and allowing it to be retained more in the raw materials remaining after essential oil extraction, and is also conducive to removing pesticide residues in the pepper raw materials.

[0012] In addition, the present invention unexpectedly found that the processing temperature and moisture content of the pepper raw material before subcritical extraction directly affect the product quality of the pepper oil obtained by subcritical extraction, and the product quality of the pepper oil directly affects the extraction effect of molecular distillation. The processing method of freezing the pepper raw material before tableting and controlling the moisture content of the pepper raw material after tableting can significantly improve the yield of pepper essential oil while reducing the loss of piperine, increase the content of piperine in the pepper raw material after essential oil extraction, and promote the entry of pesticide components into the pepper oil during the subcritical extraction process, so as to better ensure low pesticide residues in the remaining raw material after essential oil extraction.

[0013] Specifically, before the subcritical extraction, the pepper raw material is first frozen and then tableted, and the moisture content of the pepper raw material after tableting is 15-20%. If the moisture content of the pepper raw material after tableting is lower than the above range, the retention rate of piperine in the pepper raw material after essential oil extraction is reduced, which affects the quality of the subsequent preparation of pepper resin products. If the moisture content is higher than the above range, the essential oil extraction speed is slow and the efficiency is low, which affects the efficiency of industrial large-scale production.

[0014] Preferably, the freezing is performed at -10 to 5° C. for 8 to 12 hours. Freezing within this temperature range can increase the yield of pepper essential oil. If the temperature is higher than the above range, the essential oil will volatilize more, resulting in a decrease in the yield of the essential oil.

[0015] Preferably, the temperature of the pepper raw material is maintained at -10 to 5° C. during the tableting process. More preferably, the temperature is -10 to -5° C.

[0016] In the above-mentioned tabletting process, preferably, a cooling liquid at -10 to 5°C is introduced to ensure the temperature of the pepper raw material. More preferably, a cooling liquid at -10 to -5°C is introduced.

[0017] Preferably, the thickness of the pressed sheet is 0.3-0.5 mm.

[0018] The tableting can be performed using a tableting machine.

[0019] In the above-described method for extracting pepper essential oil, the extraction solvent used in the subcritical extraction is butane. Compared with other extraction solvents, the use of butane is more conducive to improving the extraction effect of pepper essential oil and pesticide residues, and reducing the amount of piperine extracted.

[0020] Preferably, the temperature of the subcritical extraction is 20-25° C. and the pressure is 0.55-0.60 MPa.

[0021] The present invention finds that the subcritical butane extraction temperature and pressure affect the content of piperine in the obtained pepper oil and the pesticide residue in the pepper raw material after extraction. When the subcritical extraction temperature and pressure are higher than the above range, the content of piperine in the obtained pepper oil is significantly increased, resulting in a decrease in the content of piperine in the pepper raw material after extraction, affecting the quality of the pepper product after extraction; when the subcritical extraction temperature and pressure are lower than the above range, the extraction speed of essential oil is slow, the efficiency is low, and industrial large-scale production is impossible.

[0022] Preferably, the subcritical extraction is performed 2-3 times, and each extraction time is 0.5-1.5h.

[0023] After subcritical extraction, pepper oil is obtained by filtration and evaporation.

[0024] In the above-described method for extracting pepper essential oil, the pressure of the molecular distillation is 1000-2000 Pa, and the heating temperature is 75-80° C. If the pressure of the molecular distillation is too high and the temperature is too low, the distillation efficiency of the essential oil will be too low, and it will be difficult to effectively separate the essential oil from the non-volatile components. If the pressure is too low and the temperature is too high, the pepper essential oil will volatilize too violently, and the essential oil cannot be condensed in time, so that the yield of the essential oil is significantly reduced.

[0025] In the above-mentioned method, the collected molecular distillation light phase is pepper essential oil.

[0026] In the method described above, the remaining pepper raw material after subcritical extraction of pepper oil can be used for the preparation of pepper oleoresin.

[0027] The invention is verified by production practice that the method for extracting pepper essential oil has a higher pepper essential oil yield, and the content of piperine in the obtained molecular distillation heavy phase is ≤1%, and the various pesticide residues in the pepper raw material after the pepper oil (subcritical extraction) is extracted are ≤0.1ppm.

[0028] Wherein, the pesticide is chlorpyrifos or metalaxyl.

[0029] The invention also provides pepper essential oil prepared by the method for extracting pepper essential oil.

[0030] The beneficial effects of the present invention are as follows: the present invention provides a method for extracting pepper essential oil, which can ensure a high extraction yield of pepper essential oil while ensuring that less piperine is extracted, and at the same time reduce the loss of piperine, thereby significantly increasing the content of piperine in the pepper raw material after essential oil extraction; the extraction method can also effectively remove pesticide residues in the pepper raw material, ensuring low pesticide residues in the pepper raw material after pepper essential oil extraction. In addition, the method is easy to operate and can be industrialized. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment provides a method for extracting pepper essential oil, and the steps are as follows:

[0034] 1. Tabletting: Take 30kg of pepper, store it at -10℃ for 10h, use a tablet press to tablet, pass coolant during tableting, the coolant temperature is -10℃, the thickness of pepper after tableting is 0.4mm, and the moisture content of pepper raw material is 16.01%;

[0035] 2. Subcritical extraction: put the 30kg pepper raw material obtained in step 1 into a subcritical device, add butane according to a solid-liquid ratio of 1:2, extract twice at 0.56MPa and 22°C, each time for 1h, filter with a 5μm filter bag, and evaporate at 55°C to obtain 3kg of subcritical pepper oil;

[0036] 3. Molecular distillation: 3 kg of subcritical pepper oil obtained in step 2 was put into a molecular distillation device and distilled under 79 ° C and 1250 Pa conditions to obtain 1200 g of pepper essential oil and 1800 g of molecular distillation heavy phase.

[0037] The yield of pepper essential oil in the above method is calculated to be 92.38%.

[0038] The subcritical pepper oil, pepper essential oil and pepper raw material after pepper oil extraction obtained by the above method were subjected to the following tests:

[0039] 1. Piperine content detection: Piperine content detection was carried out according to "GBT17528-2009 Determination of piperine content by high performance liquid chromatography". The results showed that the content of piperine in subcritical pepper oil was 0.55%, and the content of piperine in pepper raw materials after pepper oil extraction was 5.69%.

[0040] 2. Pesticide residue detection: Liquid phase mass spectrometer was used to detect various pesticide residues. The results showed that the residue of chlorpyrifos in the pepper raw material after pepper oil extraction was 0.065ppm, and the residue of metalaxyl was 0.033ppm.

[0041] Example 2

[0042] This embodiment provides a method for extracting pepper essential oil, and the steps are as follows:

[0043] 1. Tabletting: Take 30 kg of pepper, store it at -5 ° C for 8 hours, use a tablet press to tablet, pass coolant during the tableting process, the coolant temperature is -5 ° C, the thickness of the pepper after tableting is 0.45 mm, and the moisture content in the pepper raw material is 18.33%.

[0044] 2. Subcritical extraction: put the 30kg pepper raw material obtained in step 1 into a subcritical device, add butane according to a solid-liquid ratio of 1:2, extract 3 times at 0.59MPa and 24°C, each time for 0.5h, filter with a 5μm filter bag, and evaporate at 55°C to obtain 2.95kg of subcritical pepper oil.

[0045] 3. Molecular distillation: 2.85 kg of subcritical pepper oil obtained in step 2 was put into a molecular distillation apparatus and distilled under 76 ° C and 1650 Pa conditions to obtain 1168 g of pepper essential oil and 1782 g of molecular distillation heavy phase.

[0046] The yield of pepper essential oil in the above method is calculated to be 91.52%.

[0047] The subcritical pepper oil, pepper essential oil and pepper raw material after pepper oil extraction obtained by the above method were subjected to the following tests:

[0048] 1. Piperine content detection: Piperine content detection was carried out according to "GBT17528-2009 Determination of piperine content by high performance liquid chromatography". The results showed that the content of piperine in subcritical pepper oil was 0.75%, and the content of piperine in pepper raw materials after pepper oil extraction was 5.66%.

[0049] 2. Pesticide residue detection: Liquid phase mass spectrometer was used to detect various pesticide residues. The results showed that the residue of chlorpyrifos in the pepper raw material after pepper oil extraction was 0.043ppm, and the residue of metalaxyl was 0.023ppm.

[0050] Comparative Example 1

[0051] This comparative example provides a method for extracting pepper essential oil, and the steps are as follows:

[0052] 1. Tabletting: Take 30 kg of pepper, store it at 10 ° C for 10 hours, use a tablet press to tablet, pass coolant during the tableting process, the coolant temperature is 10 ° C, the thickness of the pepper after tableting is 0.4 mm, and the moisture content in the pepper raw material is 16.52%.

[0053] 2. Subcritical extraction: put the 30kg pepper raw material obtained in step 1 into a subcritical device, extract it twice at 0.56MPa and 22°C, each time for 1h, filter and evaporate to obtain 2.6kg subcritical pepper oil.

[0054] 3. Molecular distillation: The 2.6 kg subcritical pepper oil obtained in step 2 was put into a molecular distillation apparatus and distilled at 79 ° C and 1250 Pa to obtain only 864 g of pepper essential oil and 1736 g of molecular distillation heavy phase.

[0055] According to calculation, the yield of pepper essential oil in the above method is 66.5%. It can be seen that the essential oil volatilizes due to the high temperature during the tableting process, resulting in a low yield of the essential oil.

[0056] Comparative Example 2

[0057] This comparative example provides a method for extracting pepper essential oil, and the steps are as follows:

[0058] 1. Tabletting: Take 30 kg of pepper, store it at -10 ° C for 10 hours, use a tablet press to tablet, pass coolant during the tableting process, the coolant temperature is -10 ° C, the thickness of the pepper after tableting is 0.4 mm, and the moisture content in the pepper raw material is 11.03%.

[0059] 2. Subcritical extraction: put the 30kg pepper raw material obtained in step 1 into a subcritical device, extract it twice at 0.56MPa and 22°C, each time for 1h, filter and evaporate to obtain 3.2kg subcritical pepper oil.

[0060] 3. Molecular distillation: 3.2 kg of subcritical pepper oil obtained in step 2 was put into a molecular distillation apparatus and distilled at 79 ° C and 1250 Pa to obtain 1222 g of pepper essential oil and 2015 g of molecular distillation heavy phase.

[0061] The yield of pepper essential oil in the above method is calculated to be 92.38%.

[0062] The subcritical pepper oil, pepper essential oil and pepper raw material after pepper oil extraction obtained by the above method were subjected to the following tests:

[0063] 1. Piperine content detection: Piperine content detection was carried out in accordance with "GBT17528-2009 Determination of piperine content by high performance liquid chromatography". The results showed that the content of piperine in subcritical pepper oil was 8.31%, and the content of piperine in the pepper raw material after pepper oil extraction was 4.73%. It can be seen that insufficient water content in the pepper raw material will lead to excessive extraction of piperine, which in turn leads to a decrease in the piperine content of the product obtained from the pepper raw material after essential oil extraction.

[0064] 2. Pesticide residue detection: Liquid phase mass spectrometer was used to detect various pesticide residues. The results showed that the residue of chlorpyrifos in the pepper raw material after pepper oil extraction was 0.063ppm, and the residue of metalaxyl was 0.030ppm.

[0065] Comparative Example 3

[0066] This comparative example provides a method for extracting pepper essential oil, and the steps are as follows:

[0067] 1. Tabletting: Take 30 kg of pepper, store it at -10 ° C for 10 hours, use a tablet press to tablet, pass coolant during the tableting process, the coolant temperature is -10 ° C, the thickness of the pepper after tableting is 0.4 mm, and the moisture content of the pepper raw material is 16.83%.

[0068] 2. Subcritical extraction: put the 30kg pepper raw material obtained in step 1 into a subcritical device, extract it twice at 0.65MPa and 30°C, each time for 1h, and obtain 3.5kg of subcritical pepper oil after filtering and evaporation.

[0069] 3. Molecular distillation:

[0070] The 3.5 kg subcritical pepper oil obtained in step 2 was put into a molecular distillation device and distilled at 79° C. and 1250 Pa to obtain 1228 g of pepper essential oil and 2272 g of molecular distillation heavy phase.

[0071] The yield of pepper essential oil in the above method is calculated to be 94.53%. The subcritical pepper oil, pepper essential oil and pepper raw material after pepper oil extraction obtained by the above method are subjected to the following tests:

[0072] 1. Piperine content detection: Piperine content detection was carried out in accordance with "GBT17528-2009 Determination of piperine content by high performance liquid chromatography". The results showed that the content of piperine in subcritical pepper oil was 13.35%. Due to the high pressure and temperature of subcritical extraction, more piperine was extracted, which would lead to a decrease in the piperine content of the product obtained from the pepper raw material after essential oil extraction.

[0073] 2. Pesticide residue detection: Liquid phase mass spectrometer was used to detect various pesticide residues. The results showed that the residue of chlorpyrifos in the pepper raw material after pepper oil extraction was 0.036ppm, and the residue of metalaxyl was 0.012ppm.

[0074] Comparative Example 4

[0075] This comparative example provides a method for extracting pepper essential oil, and the steps are as follows:

[0076] 1. Tabletting: Take 30 kg of pepper, store it at -10 ° C for 10 hours, use a tablet press to tablet, pass coolant during the tableting process, the coolant temperature is -10 ° C, the thickness of the pepper after tableting is 0.4 mm, and the moisture content in the pepper raw material is 16.75%.

[0077] 2. Subcritical extraction: put the 30kg pepper raw material obtained in step 1 into a subcritical device, extract it twice at 0.45MPa and 15°C, each time for 1h, and obtain 2.0kg of subcritical pepper oil after filtering and evaporation.

[0078] 3. Molecular distillation: 2.0 kg of subcritical pepper oil obtained in step 2 was put into a molecular distillation apparatus and distilled under 79 ° C and 1250 Pa conditions to obtain 800 g of pepper essential oil and 1200 g of molecular distillation heavy phase.

[0079] The yield of pepper essential oil in the above method is calculated to be 41.16%.

[0080] The subcritical pepper oil, pepper essential oil and pepper raw material after pepper oil extraction obtained by the above method were subjected to the following tests:

[0081] 1. Piperine content detection: Piperine content detection was carried out according to "GBT17528-2009 Determination of piperine content by high performance liquid chromatography". The results showed that the content of piperine in subcritical pepper oil was 0.31%, and the content of piperine in pepper raw materials after pepper oil extraction was 5.46%.

[0082] 2. Pesticide residue detection: Liquid phase mass spectrometer was used to detect various pesticide residues. The results showed that the residue of chlorpyrifos in the pepper raw material after pepper oil extraction was 0.233ppm, and the residue of metalaxyl was 0.351ppm. Due to the low subcritical extraction pressure and temperature, the yield of essential oil obtained by extraction was low, the extraction efficiency was low, and the pesticide residue index in the pepper after extraction was unqualified.

[0083] Comparative Example 5

[0084] This comparative example provides a method for extracting pepper essential oil, and the steps are as follows:

[0085] 1. Tabletting: Take 30 kg of pepper, store it at -10 ° C for 10 hours, use a tablet press to tablet, pass coolant during the tableting process, the coolant temperature is -10 ° C, the thickness of the pepper after tableting is 0.4 mm, and the moisture content in the pepper raw material is 15.89%.

[0086] 2. Subcritical extraction: put the 30kg pepper raw material obtained in step 1 into a subcritical device, extract it twice at 0.56MPa and 22°C, each time for 1h, filter and evaporate to obtain 3kg of subcritical pepper oil.

[0087] 3. Molecular distillation: 3 kg of subcritical pepper oil obtained in step 2 was put into a molecular distillation device and distilled at 70 ° C and 2500 Pa to obtain 750 g of pepper essential oil and 2250 g of molecular distillation heavy phase.

[0088] The yield of pepper essential oil in the above method is calculated to be 62.5%. Due to the low molecular distillation temperature and high pressure, the yield of pepper essential oil is significantly reduced compared with Example 1, and more essential oil cannot be effectively extracted in the molecular distillation heavy phase.

[0089] Comparative Example 6

[0090] This comparative example provides a method for extracting pepper essential oil, and the steps are as follows:

[0091] 1. Tabletting: Take 30 kg of pepper, store it at -10 ° C for 10 hours, use a tablet press to tablet, pass coolant during the tableting process, the coolant temperature is -10 ° C, the thickness of the pepper after tableting is 0.4 mm, and the moisture content in the pepper raw material is 15.63%.

[0092] 2. Subcritical extraction: put the 30kg pepper raw material obtained in step 1 into a subcritical device, extract it twice at 0.56MPa and 22°C, each time for 1h, filter and evaporate to obtain 3kg of subcritical pepper oil.

[0093] 3. Molecular distillation: 3 kg of subcritical pepper oil obtained in step 2 was put into a molecular distillation device and distilled under 85 ° C, 800 Pa conditions to obtain 810 g of pepper essential oil and 1800 g of molecular distillation heavy phase.

[0094] The yield of pepper essential oil in the above method is calculated to be 62.26%. Due to the high molecular distillation temperature and low pressure, the weight loss rate of the molecular distillation step reaches 13%, and more essential oil is lost because it evaporates too quickly and has no time to condense.

[0095] Comparative Example 7

[0096] This comparative example provides a method for extracting pepper essential oil, and the steps are as follows:

[0097] 1. Tabletting: Take 30kg of pepper, store it at -10℃ for 10h, use a tablet press to tablet, pass coolant during tableting, the coolant temperature is -10℃, the thickness of pepper after tableting is 0.4mm, and the moisture content of pepper raw material is 16.01%;

[0098] 2. Supercritical extraction: put the 30kg pepper raw material obtained in step 1 into a supercritical device, add carbon dioxide according to a solid-liquid ratio of 1:2, extract 3 times at 12MPa and 40°C, each time for 1h, filter with a 5μm filter bag, and evaporate at 55°C to obtain 5kg of supercritical pepper oil;

[0099] 3. Molecular distillation: 5 kg of supercritical pepper oil obtained in step 2 was put into a molecular distillation equipment and distilled under 79 ° C and 1250 Pa conditions to obtain 1208 g of pepper essential oil and 3756 g of molecular distillation heavy phase.

[0100] The yield of pepper essential oil in the above method is calculated to be 93.01%.

[0101] The supercritical pepper oil, pepper essential oil and pepper raw material after pepper oil extraction obtained by the above method were subjected to the following tests:

[0102] 1. Piperine content detection: Piperine content detection was carried out in accordance with "GBT17528-2009 Determination of piperine content by high performance liquid chromatography". The results showed that the content of piperine in supercritical pepper oil was 15.51%, and the content of piperine in pepper raw materials after pepper oil extraction was 3.04%. During the supercritical extraction process, more piperine was extracted, which would lead to a decrease in the content of piperine in the product made from pepper raw materials after essential oil extraction.

[0103] 2. Pesticide residue detection: Liquid phase mass spectrometer was used to detect various pesticide residues. The results showed that the residue of chlorpyrifos in the pepper raw material after pepper oil extraction was 0.045ppm, and the residue of metalaxyl was 0.031ppm.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting pepper essential oil, characterized in that, The method comprises: performing subcritical extraction on pepper raw materials to obtain pepper oil, performing molecular distillation on the pepper oil, and collecting a light phase; Before the subcritical extraction, the pepper raw material is first frozen at -10 to 5°C for 8 to 12 hours and then tableted. During the tableting process, the temperature of the pepper raw material is kept at -10 to 5°C. After tableting, the moisture content of the pepper raw material is 15 to 20%. The thickness of the tablets is 0.3 to 0.5 mm. The temperature of the subcritical extraction is 20-25°C, the pressure is 0.55-0.60MPa, and the extraction solvent used is butane; the subcritical extraction is performed 2-3 times, and the extraction time each time is 0.5-1.5h; The pressure of the molecular distillation is 1000-2000 Pa, and the heating temperature is 75-80°C.