阅读说明：本技术 一种降低植物油中塑化剂的方法 (Method for reducing plasticizer in vegetable oil ) 是由 孟佳 张旋 刘建 张煜 史宣明 方晓璞 于 2021-09-27 设计创作，主要内容包括：本发明公开了一种降低植物油中塑化剂的方法,包括以下步骤：对分子蒸馏系统供给循环水、冷冻水、热水及导热油；开启温度控制,预设进料温度；当导热油升至一定温度时,启动真空泵；待系统真空度达到0.1 Pa后,设定蒸馏温度、刮膜转速,进行油脂的脱塑化剂处理；开启进料阀,启动进料泵,将待处理的植物油导入分子蒸馏系统中,调节泵后调节阀控制进料速率,启动出料泵,得到处理后的植物油。本发明通过对分子蒸馏系统的调节,完成对植物油中重点控制指标的PAEs的高效脱除。(The invention discloses a method for reducing plasticizer in vegetable oil, which comprises the following steps: supplying circulating water, chilled water, hot water and heat conducting oil to the molecular distillation system; starting temperature control, and presetting feeding temperature; when the heat conducting oil is heated to a certain temperature, starting a vacuum pump; after the vacuum degree of the system reaches 0.1Pa, setting the distillation temperature and the film scraping rotation speed, and performing plasticizer removal treatment on the grease; and opening a feed valve, starting a feed pump, introducing the vegetable oil to be treated into the molecular distillation system, adjusting a rear adjusting valve of the pump to control the feeding rate, and starting a discharge pump to obtain the treated vegetable oil. The invention completes the high-efficiency removal of PAEs with key control indexes in the vegetable oil by adjusting the molecular distillation system.)

1. A method of reducing plasticizer in vegetable oil, comprising the steps of:

step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to the molecular distillation system;

step 2, starting temperature control, and presetting feeding temperature; when the heat conducting oil is heated to a certain temperature, starting a vacuum pump; after the vacuum degree of the system reaches 0.1Pa, setting the distillation temperature and the film scraping rotation speed, and performing plasticizer removal treatment on the grease;

step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a post-pump adjusting valve to control the feeding rate;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

2. The process of claim 1 wherein said molecular distillation system is a VKL70-3FDAR molecular distillation system having an evaporation area of 0.05 square meters.

3. The method according to claim 1, wherein the temperature of the circulating water in the step 1 is 35-40 ℃, the temperature of the hot water is 50-60 ℃ and the final temperature of the heat transfer oil is 175-180 ℃.

4. The method according to claim 1, wherein the preset feeding temperature in the step 2 is 95-105 ℃; the heat conducting oil is heated to a certain temperature, and the specific temperature is 85-95 ℃.

5. The method of claim 1, wherein the distillation temperature in step 2 is 145 ℃ to 175 ℃ and the film scraping rotation speed is 150r/min to 350 r/min.

6. The method according to claim 1, wherein the feeding rate in the step 3 is 200ml/h to 700 ml/h.

Technical Field

The invention belongs to the technical field of safe processing of vegetable oil, and particularly relates to a method for reducing plasticizer in vegetable oil.

Background

Phthalate Plasticizers (PAEs) are environmental hormone-like substances, and although the phthalate plasticizers have no acute toxicity to human bodies, the toxicity of chronic toxicity accumulated in the human bodies for a long time, particularly the toxicity to reproductive development, cannot be ignored. It has been found that o-benzene plasticizers can cause dysfunction of the vas deferens, seminal vesicles and prostate in male animals, and in addition, can cause slow embryo growth and malformation. Plasticizers have become one of the most common contaminants worldwide in recent years. To avoid this, china, the united states, japan, and the european union, etc. list them as "priority control contaminants" and limit their addition amount in food contact materials.

With the increasing importance of people on food safety, the problem of plasticizers in edible oil is also receiving more and more attention under the influence of events such as drunkard wine, clouding agents and the like. Researches find that different foods have different plasticizer dissolving capacities under the same conditions, and the lipid food has the strongest dissolving capacity. In the production process of vegetable oil, processing aids, packaging materials, plastic equipment parts and the like may be used to introduce plasticizers into the oil. Due to environmental pollution, in addition to the plasticizer-enriching effect of the vegetable oil seeds, the oil seeds may also contain plasticizers and migrate into the oil along with the oil production. Therefore, the research on the effective removal of PAEs in the grease has important significance for improving the quality safety of the edible oil.

According to the research reports, the solid adsorbent can partially remove PAEs in drinking water or sewage, for example, the activated carbon-attapulgite composite filter material can remove 94% of dibutyl phthalate (DBP) in drinking water, the solid adsorbent also has a certain removing effect on dimethyl phthalate (DMP), diethyl phthalate (DEP) and di (2-ethylhexyl) phthalate (DEHP) in water, and the solid adsorbent is also used for carrying out adsorption removal research on PAEs existing in edible vegetable oil in recent years.

Previous studies have shown that PAEs migrate into deodorized distillates along with fatty acids and other volatile components during the deodorization process in oil and fat refining. Researches show that the water vapor distillation has obvious effect on removing dibutyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) in the camellia seed oil.

Zhangming et al (Zhangming, Liuyulan, Yangjin, etc. adsorption and removal of phthalate plasticizers in grease research [ J ] grain and oil food technology, 2015(5)32-36) A solid adsorbent adsorption method is adopted to research the effect of phthalate plasticizers in grease, and firstly, the contents of diisobutyl phthalate (DIBP), DBP and DEHP in raw oil are detected. Weighing 40g of oil sample, placing the oil sample in a three-neck flask, heating and stirring the oil sample to an adsorption temperature, adding a certain amount of adsorbent, continuously stirring the oil sample until the adsorption time is set, centrifuging the oil sample at 4500r/min for 30min to separate the adsorbent in the oil, and filtering the oil sample if the adsorbent still suspends in the oil to finally obtain the clean oil. The contents of DMP, DEP, DIBP, DBP, Butyl Benzyl Phthalate (BBP) and DEHP in the obtained clean oil are measured, and the removal rate is calculated. The method has good effect of removing DMP, DEP and DIBP in the tea seed oil by using an adsorption method, but has poor effect of removing DBP and DEHP which are plasticizer components with larger molecular weight, and can not reach the national standard limit regulation.

In the prior art, a steam distillation removal method is adopted, and PAEs in grease are effectively removed in a deodorization process according to the difference that the boiling point and the saturated vapor pressure of PAEs molecules are lower than those of triglyceride. The distillation temperature and the distillation time during the deodorization directly influence the removal effect. The removal rate of PAEs is gradually increased along with the increase of the distillation temperature, and the DBP and DEHP content in the soybean oil can be reduced to be below the limit of national standards at the distillation temperature of 240 ℃. Although the PAEs in the edible oil can be effectively removed by the steam distillation at high temperature for a long time, a large amount of vitamin E in the oil is lost, and a large amount of trans-fatty acid is generated.

Molecular distillation is a separation method which utilizes the fact that the mean free path of light molecules is larger and the mean free path of heavy molecules is smaller, and when the distance between an evaporation surface and a condensation surface is between the mean free paths of the light molecules and the heavy molecules, the light molecules and the heavy molecules can be separated. The molecular distillation has the advantages of low operation temperature, short heating time, reduction of damage of heat-sensitive substances and the like, is also used for purifying and refining phthalate esters in the refining industry, and has high separation degree. However, studies on the removal of plasticizers from fats and oils by molecular distillation have been rarely reported. Ordinary distillation needs to be carried out at the boiling point temperature, while molecular distillation can be carried out at any temperature, and the separation can be achieved as long as a temperature difference exists between a cold side and a hot side. However, molecular distillation has the contradiction that the distillation temperature is increased, the plasticizer removal rate is increased, and the nutrient loss rate is also increased.

Therefore, there is a need to provide a new method for reducing plasticizers in vegetable oils by molecular distillation.

Disclosure of Invention

In view of the above, the present invention provides a method for reducing plasticizers in vegetable oils, which is used for removing PAEs from edible oils by molecular distillation, and has the advantages of high efficiency of plastic removal, low operation temperature, short heating time, no generation of trans fatty acids, less loss of heat-sensitive substances, and the like, and simultaneously, no solvent is used, and thus, pollution of the solvent to the oils is avoided.

In order to solve the technical problem, the invention discloses a method for reducing a plasticizer in vegetable oil, which comprises the following steps:

step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to the molecular distillation system;

step 2, starting temperature control, and presetting feeding temperature; when the heat conducting oil is heated to a certain temperature, starting a vacuum pump; after the vacuum degree of the system reaches 0.1Pa, setting the distillation temperature and the film scraping rotation speed, and performing plasticizer removal treatment on the grease;

step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a post-pump adjusting valve to control the feeding rate;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

Optionally, the molecular distillation system is a VKL70-3FDAR molecular distillation system having an evaporation area of 0.05 square meters.

Optionally, the temperature of the circulating water in the step 1 is 35-40 ℃, the temperature of the hot water is 50-60 ℃ and the final temperature of the heat conducting oil is 175-180 ℃.

Optionally, the preset feeding temperature in the step 2 is 95-105 ℃; the heat conducting oil is heated to a certain temperature, and the specific temperature is 85-95 ℃.

Optionally, the distillation temperature in the step 2 is 145-175 ℃, and the film scraping rotation speed is 150-350 r/min.

Optionally, the feeding rate in the step 3 is 200 ml/h-700 ml/h.

Compared with the prior art, the invention can obtain the following technical effects:

1) the invention can complete the high-efficiency removal of PAEs with key control indexes in vegetable oil in 0.1Pa high vacuum and extremely short time by adjusting the operation parameters of the molecular distillation system.

2) When the molecular distillation method is used for efficiently removing PAEs in edible oil, the molecular distillation method has the advantages of low operation temperature, short heating time, no generation of trans-fatty acid, less loss of thermosensitive substances and the like, does not use any solvent, and avoids the pollution of the solvent to the oil.

Of course, it is not necessary for any one product in which the invention is practiced to achieve all of the above-described technical effects simultaneously.

Detailed Description

The following embodiments are described in detail with reference to the accompanying drawings, so that how to implement the technical features of the present invention to solve the technical problems and achieve the technical effects can be fully understood and implemented.

The invention also discloses a method for reducing the plasticizer in the vegetable oil, which comprises the following steps:

step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter;

wherein the temperature of the circulating water is 35-40 ℃, the temperature of the hot water is 50-60 ℃ and the final temperature of the heat conducting oil is 175-180 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 95-105 ℃; when the temperature of the heat conducting oil is increased to 85-95 ℃, starting a vacuum pump, setting the distillation temperature to 145-175 ℃ and the film scraping rotation speed to 150-350 r/min after the vacuum degree of the system reaches 0.1 Pa.

The molecular distillation built-in film scraper is periodically scraped, and materials are uniformly distributed on the evaporation surface of the distiller, namely, a liquid film with small and uniform thickness is formed by the movement of the film scraper, so that the mass transfer and heat transfer resistance is reduced, and meanwhile, the temperature and the concentration of the liquid film are continuously updated, so that the quality and the heat transfer process inside the liquid film are effectively enhanced. The increase of the rotating speed of the scraping film can improve the yield and the separation efficiency of the volatile components. When the rotating speed of the scraped film is increased to a certain degree, the rotating speed is continuously increased, and the improvement range of the separation efficiency and the yield is limited. Tests show that the plasticizer removal effect is not obviously improved when the speed is higher than 350rpm, and the plasticizer removal is not easy to reach the standard when the speed is lower than 150 rpm.

Distillation temperature is an important parameter in molecular distillation processes and affects the yield and purity of the desired product. When the distillation pressure is unchanged, the light molecular components in the raw materials continuously escape from the liquid film to reach the condensation surface along with the increase of the distillation temperature, and the condensation distillate quantity is gradually increased. However, too high distillation temperature is liable to cause material decomposition, and although the higher the temperature is, the higher the yield is, heavy molecules enter light molecules at this time, resulting in a decrease in purity of the target product. Above 175 ℃, the plasticizer removal effect is not obviously improved, and the comprehensive retention rate of VE and sterol is obviously reduced. The plasticizer is poor in removing effect at the temperature lower than 145 ℃.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a rear adjusting valve of the pump to control the feeding rate to be 200-700 ml/h;

the feed rate is an important factor affecting the molecular distillation process. The feeding concentration is increased, the surface temperature of a liquid film is reduced, and the distillation rate is improved. The increase of the feeding rate directly leads to the increase of the thickness of the liquid film, the slow reaching of the surface temperature of the liquid film to a steady state, the increase of the concentration of the surface and the distillate and the reduction of the distillation amount. Above 700ml/h, the plasticizer removal effect is not obviously improved, and the comprehensive retention rate of VE and sterol is obviously reduced. Below 200ml/h, the plasticizer removal effect and nutrient retention are poor.

In the actual process, the effect of plasticizer reduction can be really achieved only by considering the influence of the film scraping rotating speed, the distillation temperature and the feeding rate.

Step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

When the molecular distillation method is used for removing PAEs in grease, under the same condition, the removal rate of DMP is about 46 percent, the removal rate of DEP is about 68 percent, the removal rate of DBP can reach more than 97 percent, and the removal rate of DEHP can reach more than 70 percent. The effect of removing PAEs from grease by a molecular distillation method can also be seen that compared with the PAEs components (DMP and DEP) with smaller molecular weight, the molecular distillation method has better effect of removing high molecular weight PAEs components (DBP and DEHP) in grease, and the temperature has obvious effect on the removal effect.

Removal rate (content before reaction-content after reaction)/content before reaction × 100%;

the comprehensive retention rate of the vitamin E and the phytosterol can reach more than 75 percent.

The comprehensive retention rate of vitamin E and phytosterol (vitamin E content after reaction + phytosterol content after reaction)/(vitamin E content before reaction + phytosterol content before reaction) × 100%.

The detection methods of three plasticizers, namely DBP, DEHP and DINP, are GB 5009.271-2016.

Example 1

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 38 ℃, the temperature of the hot water is 55 ℃ and the final temperature of the heat-conducting oil is 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 100 ℃; when the temperature of the heat conducting oil is increased to 90 ℃, starting a vacuum pump, setting the distillation temperature to be 155 ℃ and the film scraping rotation speed to be 230r/min after the vacuum degree of the system reaches 0.1 Pa.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a regulating valve after the pump to control the feeding rate to be 600 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

Through detection, the DBP content in the oil is reduced from 1.55mg/kg to no detection, the removal rate is 100 percent, the DEHP content is reduced from 4.85mg/kg to 0.99mg/kg, the removal rate is 85 percent, and the DBP content reaches below the limit of national standards; the comprehensive retention rate of vitamin E and phytosterol is 87.31%.

Example 2

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 35 ℃, the temperature of the hot water is 50 ℃ and the final temperature of the heat conducting oil is 180 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 100 ℃; when the temperature of the heat conducting oil is increased to 90 ℃, starting a vacuum pump, setting the distillation temperature to be 170 ℃ and the film scraping rotating speed to be 350r/min after the vacuum degree of a system reaches 0.1 Pa.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a rear adjusting valve of the pump to control the feeding rate to be 700 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

Through detection, the DBP content in the oil is reduced from 1.55mg/kg to no detection, the removal rate is 100%, the DEHP content is reduced from 4.85mg/kg to 0.87mg/kg, the removal rate is 97.4%, the content reaches below the limit of national standards, and the comprehensive retention rate of vitamin E and phytosterol is 85.57%.

Example 3

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 40 ℃, the temperature of the hot water is 60 ℃ and the final temperature of the heat conducting oil is about 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 100 ℃; when the temperature of the heat conducting oil is increased to 90 ℃, starting a vacuum pump, setting the distillation temperature to be 155 ℃ and the film scraping rotation speed to be 230r/min after the vacuum degree of the system reaches 0.1 Pa.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a rear adjusting valve of the pump to control the feeding rate to be 300 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

Through detection, the DBP content in the oil is reduced from 3.46mg/kg to no detection, the removal rate is 100%, the DEHP content is reduced from 34.0mg/kg to 1.09mg/kg, the removal rate is 96.8%, the content reaches below the limit of national standards, and the comprehensive retention rate of vitamin E and phytosterol is 80.09%.

Example 4

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 38 ℃, the temperature of the hot water is 55 ℃ and the final temperature of the heat-conducting oil is 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 95 ℃; when the temperature of the heat conducting oil is increased to 95 ℃, starting a vacuum pump, setting the distillation temperature to 145 ℃ after the vacuum degree of the system reaches 0.1Pa, and scraping the film at the rotating speed of 350 r/min.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a regulating valve after the pump to control the feeding rate to be 200 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

Through detection, the DBP content in the oil is reduced from 3.46mg/kg to no detection, the removal rate is 100%, the DEHP content is reduced from 34.0mg/kg to 1.31mg/kg, the removal rate is 96.1%, the content reaches below the limit of national standard, and the comprehensive retention rate of vitamin E and phytosterol is 83.64%.

Example 5

A method of reducing plasticizer in vegetable oil comprising the steps of:

step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 38 ℃, the temperature of the hot water is 58 ℃ and the final temperature of the heat conducting oil is about 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 105 ℃; when the temperature of the heat conducting oil is increased to 85 ℃, starting a vacuum pump, setting the distillation temperature to 175 ℃ and the film scraping rotation speed to 150r/min after the vacuum degree of the system reaches 0.1 Pa.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a rear adjusting valve of the pump to control the feeding rate to be 700 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

Through detection, the DBP content in the oil is reduced from 3.46mg/kg to no detection, the removal rate is 100%, the DEHP content is reduced from 34.0mg/kg to 1.42mg/kg, the removal rate is 95.8%, the content reaches below the limit of national standard, and the comprehensive retention rate of vitamin E and phytosterol is 78.17%.

Comparative example 1

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 30 ℃, the temperature of the hot water is 55 ℃ and the final temperature of the heat conducting oil is about 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 100 ℃; when the temperature of the heat conducting oil is increased to 90 ℃, starting a vacuum pump, setting the distillation temperature to be 155 ℃ and the film scraping rotation speed to be 230r/min after the vacuum degree of the system reaches 0.1 Pa.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a rear adjusting valve of the pump to control the feeding rate to be 800 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

The detection proves that the DBP content in the oil is reduced from 1.55mg/kg to 0.45mg/kg, the removal rate is 71 percent, the DEHP content is reduced from 4.85mg/kg to 1.87mg/kg, the removal rate is 61.4 percent, and both the DBP content and the DEHP content do not reach below the limit of national standards. The comprehensive retention rate of vitamin E and phytosterol is 70.17%.

Comparative example 2

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 38 ℃, the temperature of the hot water is 55 ℃ and the final temperature of the heat conducting oil is about 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 100 ℃; when the temperature of the heat conducting oil is increased to 90 ℃, starting a vacuum pump, setting the distillation temperature to be 180 ℃ and the film scraping rotating speed to be 350r/min after the vacuum degree of a system reaches 0.1 Pa;

step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a regulating valve after the pump to control the feeding rate to be 600 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

Through detection, the DBP content in the oil is reduced from 1.55mg/kg to no detection, the removal rate is 100 percent, the DEHP content is reduced from 4.85mg/kg to 1.53mg/kg, the removal rate is 68.5 percent, and the DEHP content does not reach below the limit of national standard. The comprehensive retention rate of vitamin E and phytosterol is 69.33%.

Comparative example 3

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 38 ℃, the temperature of the hot water is 55 ℃ and the final temperature of the heat conducting oil is about 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 100 ℃; when the temperature of the heat conducting oil is increased to 90 ℃, starting a vacuum pump, setting the distillation temperature to be 120 ℃ and the film scraping rotating speed to be 360r/min after the vacuum degree of a system reaches 0.1 Pa.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a regulating valve after the pump to control the feeding rate to be 600 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

The detection proves that the DBP content in the oil is reduced from 3.46mg/kg to 0.46mg/kg, the removal rate is 86.7 percent, the DEHP content is reduced from 34.0mg/kg to 2.63mg/kg, the removal rate is 92.3 percent, and the DBP and DEHP contents do not reach below the limit of national standards. The comprehensive retention rate of vitamin E and phytosterol is 75.72%.

Comparative example 4

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 38 ℃, the temperature of the hot water is 55 ℃ and the final temperature of the heat conducting oil is about 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 100 ℃; when the temperature of the heat conducting oil is increased to 90 ℃, starting a vacuum pump, setting the distillation temperature to be 140 ℃ and the film scraping rotation speed to be 390r/min after the vacuum degree of a system reaches 0.1 Pa.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a rear adjusting valve of the pump to control the feeding rate to be 100 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

The detection proves that the DBP content in the oil is reduced from 3.46mg/kg to 0.82mg/kg, the removal rate is 76.3 percent, the DEHP content is reduced from 34.0mg/kg to 2.82mg/kg, the removal rate is 91.7 percent, and the DBP and DEHP contents do not reach below the limit of national standards. The comprehensive retention rate of vitamin E and phytosterol is 73.25%.

Comparative example 5

Step 1, pretreatment: supplying circulating water, chilled water, hot water and heat conducting oil to a distillation system (VKL70-3FDAR) with an evaporation area of 0.05 square meter; wherein the temperature of the circulating water is 38 ℃, the temperature of the hot water is 55 ℃ and the final temperature of the heat conducting oil is about 175 ℃;

step 2, starting temperature control, and presetting a feeding temperature of 100 ℃; when the temperature of the heat conducting oil is increased to 90 ℃, starting a vacuum pump, setting the distillation temperature to be 175 ℃ and the film scraping rotation speed to be 110r/min after the vacuum degree of a system reaches 0.1 Pa.

Step 3, feeding: starting a feeding valve, starting a feeding pump, introducing the vegetable oil to be treated into a molecular distillation system, and adjusting a rear adjusting valve of the pump to control the feeding rate to be 100 ml/h;

step 4, discharging: starting the discharging pump to obtain the treated vegetable oil.

The detection proves that the DBP content in the oil is reduced from 3.46mg/kg to 0.63mg/kg, the removal rate is 81.8 percent, the DEHP content is reduced from 34.0mg/kg to 3.39mg/kg, the removal rate is 90 percent, and both the DBP content and the DEHP content do not reach below the limit of national standards. The comprehensive retention rate of vitamin E and phytosterol is 74.81%.

While the foregoing description shows and describes several preferred embodiments of the invention, it is to be understood, as noted above, that the invention is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.