A method for efficiently separating solid fat from a polyunsaturated fatty acid oil

Abstract

The application provides a method for efficiently separating solid grease from polyunsaturated fatty acid oil, which comprises adding a certain amount of inert substances into the polyunsaturated fatty acid oil, cooling and crystallizing, and then filtering through a filter to obtain clear polyunsaturated fatty acid oil, and then passing hot gas into the filter to dissolve the solid grease adsorbed on the filter cake and recover the solid grease through the filter plate, and the inert solid substances can be reused next time. Through the method, saturated and low-saturated fatty acid solid grease can be efficiently separated from the polyunsaturated fatty acid oil, the winterization crystallization time in the process is short, the crystallization is complete, the crystal separation is easy, and the phenomenon that part of the solid grease melts and reenters the filtrate due to long separation and drying time in the conventional process does not occur, so that the yield of the final product is as high as 89.8%-97.8%, and the polyunsaturated fatty acid oil after winterization treatment is clear, and no crystal is precipitated at 0 DEG C for 5 hours.

Description

TECHNICAL FIELD

[0001] The present application relates to a process for efficiently separating solid fat from polyunsaturated fatty acid oil, in particular, the present application adds a certain amount of inert material to the polyunsaturated fatty acid oil, stirs slowly, cools and crystallizes, filters to obtain clear polyunsaturated fatty acid oil, then uses hot air or steam to melt the solid fat adsorbed in the filter cake, and collects it through a filter plate. This process not only makes the polyunsaturated fatty acid oil clearer, but also efficiently collects the solid fat, and is suitable for winterization operations of one or more polyunsaturated fatty acid mixtures including fish oil (directly extracted omega-3 polyunsaturated fatty acids), algal oil (fermented omega-3 polyunsaturated fatty acids), linoleic acid, conjugated linoleic acid, linolenic acid, arachidonic acid, etc. It belongs to the field of biological chemical engineering. BACKGROUND

[0002] As people pay more and more attention to their health, the public begins to take more nutritional health dietary supplements, and polyunsaturated fatty acid (PUFA) products play an important role among them. Polyunsaturated fatty acids refer to fatty acids with at least two double bonds in their molecular structure, which exist in the form of fatty acid ethyl ester, fatty acid methyl ester, fatty acid glyceride, and free fatty acid, etc.

[0003] Polyunsaturated fatty acids (PUFA) are important material basis for body metabolism, especially the development of infant brain, are components of cell membranes, and mainly play physiological functions such as maintaining cell membrane fluidity, promoting cholesterol esterification, reducing cholesterol and triglyceride, reducing blood viscosity, and improving blood circulation, etc. In addition, polyunsaturated fatty acids (PUFA) also have the functions of improving human thinking and enhancing memory. However, the human body cannot synthesize polyunsaturated fatty acids (PUFA) and must obtain them through diet, etc.

[0004] Polyunsaturated fatty acids (PUFA) are diverse, mainly including omega-3 polyunsaturated fatty acids (PUFA) (omega-3 PUFA), omega-6 polyunsaturated fatty acids (PUFA) (omega-6 PUFA), omega-9 polyunsaturated fatty acids (PUFA) (omega-9 PUFA), etc. such as alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), linoleic acid (LA), conjugated linoleic acid (CLA), gamma-linolenic acid (GLA), arachidonic acid (AA), etc. Among them, omega-3 polyunsaturated fatty acids (omega-3 PUFA) represented by eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the most well-known and accepted by the public, and have the most obvious improvement and promotion effects on human and animal health. The molecular structure formulas of some polyunsaturated fatty acids are as follows:

[0005]

[0006]

[0007] The main source of polyunsaturated fatty acids is from algae extract and aquatic animal oil, one of the important sources is fish oil. Because the fatty acid composition of polyunsaturated fatty acid oil is relatively complex, containing saturated, monounsaturated, polyunsaturated fatty acids, etc., the melting points of these fatty acids are quite different, such as C16:0, C18:0, C20:0, etc. saturated fatty acids will coagulate into solid state at about 10℃, even 20℃, while C16:2, C18:1, C18:2, etc. Monounsaturated or diunsaturated fatty acids do not precipitate at 0℃, C16:4, C18:3, C20:4, C20:5, C22:6, etc. Polyunsaturated fatty acids remain clear below-10℃. The so-called solid fat refers to saturated fatty acids such as C16:0, C18:0, C20:0, etc. and even C16:2, C18:1, C20:1, etc. low saturated fatty acids, which are a class of substances with relatively high melting point.

[0008] Most of the polyunsaturated fatty acids, especially the functional polyunsaturated fatty acid oils such as fish oil, conjugated linoleic acid, etc. are mainly used in dietary supplement field. In the field of dietary supplements, these polyunsaturated fatty acids are often taken in the form of transparent soft capsules, and the contents of soft capsules are required to be transparent as much as possible from the appearance. The final product standard of polyunsaturated fatty acid related products in industry has certain requirements on the clarity of the product, that is, colorless to light yellow transparent liquid, so the process of industrial preparation of polyunsaturated fatty acid products basically includes winterization process, the main purpose of which is to remove saturated components or low saturated components with less double bonds, i.e. solid fat, in polyunsaturated fatty acids, on the one hand to improve its physiological function, and on the other hand to maintain its clarity.

[0009] Although there is no physiological function of softening blood vessels and reducing cholesterol, saturated fatty acids or low unsaturated fatty acids (containing 1-2 double bonds in the molecular structure formula) are still useful in supplementing animal fat and providing energy, and can be widely used in food or animal feed field, or used in other industrial purposes.

[0010] In industrial production, especially in the preparation of polyunsaturated fatty acid raw materials for soft capsules, the polyunsaturated fatty acids are generally winterized to remove saturated and low-saturated fatty acids, that is, the polyunsaturated fatty acids are cooled to 0°C or below 0°C for a period of time, and the fatty acids with a freezing point below 0°C or below 0°C are crystallized and precipitated, and then the precipitated fatty acids (solid fat) are removed by filtration. In this process, how to make the saturated or low-saturated components fully crystallize and precipitate while ensuring that the polyunsaturated components do not precipitate as much as possible to ensure product yield, and how to effectively separate the crystallized and precipitated saturated or low-saturated components (solid fat) from the polyunsaturated fatty acids that have not crystallized are very critical operation steps.

[0011] For oils with a high content of medium and low carbon chain saturated fatty acid components (such as C12:0, C14:0, C16:0) in their fatty acid composition, these medium and low carbon chain saturated fatty acids have a high freezing point and are easy to crystallize and precipitate, and the obtained crystal form is relatively coarse, so they are relatively easy to crystallize and precipitate, and the subsequent crystallization and separation process is also relatively easy. However, for oils with a low content of medium and low carbon chain saturated fatty acid components and only a small amount of medium and long carbon chain low-saturated fatty acids (such as C18:1, C19:2, C20:1, C20:2, C21:1, C21:2, etc.) in their fatty acid composition, on the one hand, the crystallization temperature required is low due to the small amount of crystal seeds in the cooling and crystallization process, leading to difficult crystallization and precipitation, slow crystallization, and sometimes even incomplete precipitation, failing to achieve the winterization crystallization effect; on the other hand, the subsequent crystallization and separation process is difficult, and long-time pressure filtration is required through plate and frame separation, and compressed air or nitrogen is used for long-time blowing in order to dry the filter cake, in the process, part of the crystals in the plate and frame dissolve due to the increase in temperature and re-enter the unsaturated components, resulting in an unsatisfactory winterization effect.

[0012] In addition, for these medium and long carbon chain fatty acids containing only a small amount of low-saturated fatty acids, on the one hand, the amount of crystallization obtained by winterization is small, and the filter cake cannot form a fixed shape during pressure filtration, and on the other hand, the low-saturated components have a relatively low melting point and are easy to melt in air, leading to partial melting during plate and frame residue removal, resulting in incomplete discharge of the filter cake during residue removal, and partial adhesion of the filter cake to the plate and frame filter cloth, which reduces the winterization effect and efficiency, the low-melting-point components adhered are easy to melt and enter the unsaturated fatty component filtrate after winterization, reducing the winterization efficiency, and the precipitated low-saturated components cannot be effectively reused, reducing the process economy.

[0013] In the prior art, a large number of studies have been conducted to improve the winterization crystallization efficiency and separation efficiency of polyunsaturated fatty acids from the aspects of process or equipment innovation.

[0014] CN12552198A discloses a secondary slow cooling fish oil winterization process and a filter device used therein. The high solidification point fish oil is precipitated in a large amount by cooling stirring, standing and crystallization, and filtering to remove crystals. The precipitated fish oil crystals are not easy to re-melt, and the crystals are separated by a relatively complex customized device. The filtering area of the device is small, the design is complex, and the separation efficiency is low, especially for crystallization and separation of low-saturation crystalline components containing only a small amount of relatively low solidification point components.

[0015] CN205501251A describes a simple device for fish oil winterization, which realizes heating, dissolving, cooling, crystallizing, winterization filtering and the like in the same tank. The device realizes the processes of heating, cooling and filtering in one set of equipment, and the heat exchange area and the filtering area are small, the efficiency is low, the operation time is long, and the practicability is poor in production.

[0016] CN103740462B discloses an oil refining method, which includes a desaturated fat process, i.e. the oil and fat after impurity removal, degumming, deacidification and deodorization are further dissolved by heating in a winterization tank, crystallized by stage cooling, and then filtered by a winterization filter after long-time crystallization, to obtain refined oil with removed saturated oil. The crystallization and crystallization time are long, and the filtering is difficult, so the production efficiency is low.

[0017] CN206529439U discloses a fish oil winterization and separation crystallization and crystallization reaction tank, which introduces nitrogen during the winterization and separation crystallization process to solve the problem of difficult escape of odor and improve the heat transfer efficiency. However, the device does not describe the separation process of the crystallization, and has the disadvantages of slow separation speed and long time.

[0018] CN1605617A describes a precise micropore filtering method and device for dewaxing fat of winterized edible oil. In the method, after the winterized edible oil is stopped, compressed air is used for pressure filtration. After the pressure filtration is completed, the remaining material backflow valve at the lower part is opened to empty the remaining material in the machine. The bottom cover is opened, and compressed air is used for back blowing to make the fat and wax filter cake fall off through the bottom slag discharge port. After back blowing for 4-6 times, the bottom cover is closed, and the next batch of filtration is carried out. When the filtering pipe is blocked, the compressed air is heated to regenerate the micropore filtering pipe. In the process and device, on the one hand, the fat and wax winterized should have a certain amount, so that the formed filter cake is thick enough to be blown off. On the other hand, the filtering pipe needs to be regenerated by back blowing with hot compressed air frequently, which is relatively complicated in operation and reduces the efficiency.

[0019] A tea oil seed extraction tea oil squeezing process is disclosed in CN109897726A, including early tea oil seed treatment, squeezing, filtering, degumming, dewaxing, deacidification and other processes. In the dewaxing process, a large amount of crystal-promoting filter aid is added at one time, and activated carbon and perlite are used to promote crystallization and filtration at the same time. A large amount of crystal-promoting agent is added at one time, which will inevitably cause more crystals to precipitate, and many fatty acids that should not be precipitated at the crystallization temperature will be adsorbed on the crystal-promoting agent, thereby greatly reducing the yield of the final product.

[0020] In general, the previous oil winterization refining technology has several defects: first, the crystallization efficiency is low. Especially for raw materials with low saturated fatty acid content and only a small amount of low-saturation fatty acid with low freezing point, it is difficult for the crystal to precipitate, and the winterization crystallization efficiency is lower; second, the separation efficiency of the precipitated crystal is low. The fatty acid solid fat is difficult to separate, and if the main component of these solid fats is low-saturation fatty acid, it is difficult to separate the filtrate and solid fat quickly and completely in the plate frame or other ways, and in the long separation process, part of the low freezing point solid will easily dissolve into the filtrate, thereby reducing the quality of the clarified liquid and the winterization efficiency; third, the large amount of crystal-promoting filter aid added at one time greatly reduces the yield of the final product.

[0021] In particular, in the previous literature, the solid fat precipitated by winterization is not well recovered or the recovery method is complex. For example, it is reported that the filter aid adsorbed with solid fat is re-put into the reaction kettle for heating and dissolution, and then the solid fat in molten state is obtained by filtering. In this process, the filter cake of polyunsaturated fatty acid during filtration is first unloaded from the filter, then transferred to the reaction kettle for heating and dissolution, and then filtered by the filter to recover the solid fat. The process involves unloading, transporting, re-feeding, dissolving, re-filtering, re-unloading, and re-transporting of solid materials. For saturated adsorbed polyunsaturated fatty acid solid cake, these operations are extremely unfavorable in terms of labor intensity and environmental protection! SUMMARY

[0022] In view of the defects of the previous technology, it is necessary to find a method that can efficiently winterize and crystallize saturated and low-saturation fatty acids in oil, and efficiently separate the solid fat precipitated by winterization and crystallization, and enhance its economic efficiency.

[0023] In order to achieve the above-mentioned purpose, the present application provides a method for efficiently separating solid fat from polyunsaturated fatty acid oil. Specifically, a certain amount of inert solid powder is added to the polyunsaturated fatty acid oil before winterization and separation. The small amount of inert solid powder can act as a crystal seed, which is conducive to the crystallization of saturated or low-saturated components in the oil during cooling and the growth of crystal form during crystal growth. Thus, the disadvantages of slow crystal precipitation and long crystal growth time are overcome. At the same time, the inert solid powder can act as a filter aid during crystal separation, which is conducive to the efficient separation of crystals and avoids the re-melting of crystals during long-term filtration and the entry of the re-melted crystals into the filtrate, thereby reducing the winterization effect and efficiency of the final product. After filtration, the filter cake is not unloaded from the filter, but hot steam or hot air is directly introduced into the filter to melt the solid fat adsorbed in the inert solid powder. The melted solid fat is then collected and recovered through the filter plate. The filter cake (inert solid powder) after separation of the solid fat can be reused.

[0024] The specific operation steps of the method of the present application are as follows: a) adding a certain amount of inert solid powder to the heated and melted polyunsaturated fatty acid oil, stirring uniformly, and the inert solid powder is selected from one or a mixture of several of activated carbon, activated clay, diatomite, and perlite; b) cooling and crystallizing the polyunsaturated fatty acid oil with the inert solid powder added in step a) to obtain a crystalline mixture; c) filtering the crystalline mixture in step b) through a filter to obtain clear polyunsaturated fatty acid oil and filter cake; d) introducing hot gas into the filter to melt the solid fat into a liquid state and recover the liquid solid fat; e) introducing nitrogen gas into the filter to dry the residual solid fat; and f) recovering the filter cake inert solid powder.

[0025] Here, the solid fat refers to saturated and low-saturated fatty acid components in polyunsaturated fatty acid oil, such as C12:0, C14:0, C16:0, C18:1, C19:2, C20:1, C20:2, C21:1, C21:2, etc. The solidification point of this part of fatty acids is relatively high compared to that of polyunsaturated fatty acids.

[0026] In a preferred technical solution of the method of the present application, preferably, the polyunsaturated fatty acid oil includes one or a mixture of several of fish oil, algal oil, linoleic acid, conjugated linoleic acid, linolenic acid, and arachidonic acid. Preferably, the polyunsaturated fatty acid can be in the form of methyl ester, ethyl ester, glyceride, or free fatty acid.

[0027] In a preferred technical solution of the method of the present application, preferably, in step a), the melting temperature of the polyunsaturated fatty acid oil is 30-100°C. In this way, the oil is completely clarified and transparent. Preferably, in step a), the added amount of the inert solid powder is 0.1-6.0% (w / w) of the mass of the polyunsaturated fatty acid oil. More preferably, the added amount of the inert solid powder is 0.1-1.0% (w / w) of the mass of the polyunsaturated fatty acid oil.

[0028] In a preferred technical solution of the method of the present application, preferably, in step b), the temperature of the cooling crystallization is -10°C-5°C. And preferably, the crystal growth is maintained for 0.5-3.0 hours to form a crystallization liquid. Due to the presence of a certain amount of inert solid powder in the melted fatty acid oil, this part of the powder functions as a kind of crystal seed in a certain sense, so that the saturated components and low-saturated components (solid fat) in the fatty acid oil are easily precipitated in the form of crystals, and most of the precipitated solid fat is adsorbed on the inert solid powder. Due to the presence of the inert powder, not only is the crystallization easy to precipitate, but also the crystal growth is good, the crystal form is coarse, which is beneficial to the subsequent separation process.

[0029] After the completion of the crystal growth, the crystallization liquid with the added inert solid powder is subjected to solid-liquid separation by a filter. Due to the filter aid effect of the inert solid substance, the solid-liquid separation is very easy. In the conventional winterization crystallization method without adding inert substances, it often takes more than 10 hours to achieve solid-liquid separation, and sometimes even about 24 hours, and a large amount of nitrogen or compressed air is required to blow dry the residual liquid oil in the crystallization in the later stage, which not only causes unnecessary waste, but also, in the long filtration or blow-drying process, part of the precipitated crystals will re-melt and enter the filtrate, greatly reducing the winterization crystallization effect. By using the process disclosed in the present application, due to the addition of the inert solid powder, the crystals precipitated in the early stage are coarse and adsorbed on the inert powder medium, and the filter aid effect of the inert powder, the solid-liquid separation is relatively easy. It is found that, under the same filter area, the solid-liquid separation time is more than 1 time shorter than that of the conventional method, generally about 3 hours, and only a small amount of nitrogen or compressed air is required to blow dry to obtain a relatively dry filter cake in the later stage.

[0030] Considering that when the inert solid powder is added at one time, a large amount of fatty acid components that should not be precipitated will be entrained and precipitated due to the large amount of crystal seeds added, thereby reducing the yield of the final product, the inert solid powder can also be added in batches, that is, a small amount of inert solid powder is added before the cooling crystallization, the crystallization is carried out, and after the completion of the crystal growth, the remaining inert solid powder is added, and then the mixture is stirred uniformly and filtered by a filter as shown in Figure 1

[0031] ​Therefore, in the preferred technical solution of the method of the present application, preferably, in step b), a certain amount of the inert solid powder is added before filtration after the cooling crystallization. Preferably, in step b), the amount of the inert solid powder added before filtration after the cooling crystallization is 0.5-6.0% (w / w) of the mass of the polyunsaturated fatty acid oil.

[0032] As shown in Figure 1 The crystallization liquid containing the inert solid powder is filtered through the filter V101, the inert solid powder and the crystallized solid fat adhere to the filter plate to form a filter cake, and the clarified filtrate is collected through V201. After the filtration is completed, V101 and V201 are closed, V102 is opened to introduce hot gas, the temperature in the cavity of the filter is increased, the solid fat adsorbed on the inert solid powder in the cavity of the filter is melted, and at the same time, due to the pressure of the hot gas, the melted solid fat passes through the filter plate, the liquid collection pipe, and V202 for collection. When no liquid flows out of V202, V102 is closed, and a nitrogen valve V103 is opened to blow dry the filter cake. Finally, the cover plate of the filter is opened, and the inert solid filter cake is recovered for use in the next batch.

[0033] In the preferred technical solution of the method of the present application, preferably, in step d), the hot gas is heated steam, heated nitrogen, or heated air; and the temperature of the hot gas is 30-100℃. More preferably, the temperature of the hot gas is 80-100℃.

[0034] The recovered solid fat can be used as food, feed, or other industrial purposes, and the recovered filter cake is an inert medium, which can be preserved in nitrogen and used for winterization crystallization of the next batch of fatty acid oil.

[0035] By the method of the present application, saturated and low-saturated fatty acid solid fat can be efficiently separated from polyunsaturated fatty acid oil. The winterization crystallization time in the process is short, the crystallization is complete, the crystal separation is easy, and the phenomenon of partial solid fat melting and re-entering the filtrate due to long separation and drying time in the conventional process does not occur. Not only the final product yield is as high as 89.8%-97.8%, but also the polyunsaturated fatty acid oil after winterization treatment has good clarity, and no crystals are precipitated at 0℃ for 5 hours. The solid fat recovery is convenient, the recovery efficiency is high, and the operation is closed. The inert medium added in the process can be repeatedly used, no additional solid waste is generated, and the environmental protection performance is good. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A schematic diagram of a filter for filtering and recovering solid fat. DETAILED DESCRIPTION

[0037] The present application will be further described below in conjunction with the embodiments and drawings of the present application, and the embodiments of the present application are only used to illustrate the technical solutions of the present application, and not to limit the present application.

[0038] Example 1

[0039] 1800g of ethyl ester-type polyunsaturated fatty acid fish oil raw material (EPA 22.4%, DHA 8.7%, total polyunsaturated fatty acid content 34.5%, orange-red color) was dissolved at 65℃ for 0.5 hours, and then 9.0g of activated clay was added. The mixture was then cooled to winterize and crystallize, with the temperature lowered from 65℃ to -2.5℃ within 30 minutes, and the crystals were kept at this temperature for 20 minutes. Then, 60.0g of activated clay and 48.0g of activated carbon were added, and the mixture was stirred for another 0.5 hours.

[0040] like Figure 1 As shown, the crystallization liquid feed valve V101 of the filter is opened to filter the crystallization liquid containing activated clay and activated carbon. The polyunsaturated fatty acid filtrate passes through the filter plate to the liquid collection pipe, and then through the filtrate outlet valve V201. The collected filtrate weighs 1731.6g, with a yield of 96.2%.

[0041] Take 20 ml of the filtrate and keep it at 0℃ for 5 hours. If it remains clear and transparent, it indicates that the winterization effect is very good.

[0042] like Figure 1 As shown, close the crystallization liquid feed valve V101 and the filtrate discharge valve V201. Introduce 100°C heated nitrogen gas through V102 to melt the solids adsorbed in the filter cake. The melted solids then pass through the filter plate into the liquid collection pipe and are collected through valve V202. Finally, 58.8g of filtrate (solids) is recovered. The filter cake is then dried with nitrogen gas, and the filter cover is opened. The recovered filter cake can be reused in the next winterization process.

[0043] Example 2

[0044] Using 3000g of the same raw material as in Example 1, the solution was dissolved at 100°C for 0.5 hours. The solution was then slowly cooled to allow for winterization crystallization, with the temperature decreasing from 100°C to -10.0°C over 3.0 hours, and maintained at this temperature for 20 minutes. 3.0g of activated carbon was then added, and the mixture was stirred for another 0.5 hours.

[0045] like Figure 1 As shown, the crystallization liquid feed valve V101 of the filter is opened to filter the crystallization liquid containing activated carbon. The polyunsaturated fatty acid filtrate passes through the filter plate to the liquid collection pipe, and then through the filtrate outlet valve V201. The collected filtrate weighs 2934.2g, with a yield of 97.8%.

[0046] Take 20 ml of the filtrate and keep it at 0℃ for 5 hours. If it remains clear and transparent, it indicates that the winterization effect is very good.

[0047] like Figure 1As shown, close the crystallization liquid feed valve V101 and the filtrate discharge valve V201. Introduce heated nitrogen gas at 30°C through V102 to melt the solids adsorbed in the filter cake. The melted solids then pass through the filter plate into the liquid collection pipe and are collected through valve V202. Finally, 57.9g of filtrate (solids) is recovered. The filter cake is then dried with nitrogen gas, and the filter cover is opened. The recovered filter cake can be reused in the next winterization process.

[0048] Example 3

[0049] Using 3500g of the same raw material as in Example 1, the solution was dissolved at 65°C for 0.5hr. 60g of activated clay and 150g of activated carbon were added, and the solution was slowly cooled to allow for winterization crystallization. When the temperature was lowered from 65°C to -2.5°C within 2.5hr, a large amount of crystals precipitated. The solution was then kept at this temperature for 20min to allow for crystal growth.

[0050] like Figure 1 As shown, the crystallization liquid feed valve V101 of the filter is opened to filter the crystallization liquid containing activated clay and activated carbon. The polyunsaturated fatty acid filtrate passes through the filter plate to the liquid collection pipe, and then through the filtrate outlet valve V201. The collected filtrate weighs 3300.5g, with a yield of 94.3%.

[0051] Take 20 ml of the filtrate and keep it at 0℃ for 5 hours. If it remains clear and transparent, it indicates that the winterization effect is very good.

[0052] like Figure 1 As shown, close the crystallization liquid feed valve V101 and the filtrate discharge valve V201. Introduce 100°C superheated steam through V102 to melt the solids adsorbed in the filter cake. The melted solids then pass through the filter plate into the liquid collection pipe and are collected through valve V202. Finally, 157.2g of filtrate (solids) is recovered. The filter cake is then dried with nitrogen. The filter cover is opened, and the recovered filter cake can be reused in the next winterization process.

[0053] Example 4

[0054] 2000g of triglyceride-type algal oil polyunsaturated fatty acid raw material (EPA 3.4%, DHA 24.6%, total polyunsaturated fatty acid content 31.2%, orange-red color) obtained by fermentation was dissolved at 30℃ for 1.5 hours, and 2g of perlite was added. The mixture was then cooled to winterization crystallization, and the temperature was lowered to -10.0℃ within 45 minutes, and the crystals were kept at this temperature for 30 minutes. 40g of diatomaceous earth was then added, and the mixture was stirred for another 0.5 hours.

[0055] like Figure 1 As shown, the crystallization liquid feed valve V101 of the filter is opened to filter the crystallization liquid containing perlite and diatomaceous earth. The polyunsaturated fatty acid filtrate passes through the filter plate to the liquid collection pipe, and then through the filtrate outlet valve V201. The collected filtrate weighs 1902.0g, with a yield of 95.1%.

[0056] Take 20 ml of the filtrate, keep it at 0 °C for 5 hours, it is still clear and transparent, indicating that the winterization effect is very good.

[0057] As shown in Figure 1 , close the crystallization liquid feed valve V101, filter liquid outlet valve V201, through V102 into 30 °C hot air, so that the solid fat adsorbed in the filter cake is melted, and enters the liquid collection tube through the filter plate, is collected through valve V202, and finally the filtrate (solid fat) 77.9 g is recovered. Finally, the filter cake is blown dry with nitrogen, the filter cover is opened, and the filter cake can be recycled for the next winterization process.

[0058] Example 5

[0059] 3000 g of free conjugated linoleic acid raw material (content 78.5%) was dissolved at 100 °C for 1.0 hr, and 30 g of diatomite was added. The temperature was reduced to 5 °C within 60 min, and the temperature was kept for 45 min. 75 g of diatomite was added, and stirred for 0.5 hr.

[0060] As shown in Figure 1 , open the filter machine crystallization liquid feed valve V101 to filter the crystallization liquid containing diatomite, and the polyunsaturated fatty acid filtrate passes through the filter plate to the liquid collection tube, and then passes through the filtrate outlet valve V201. The filtrate is collected and weighed as 2826.0 g, with a yield of 94.2%.

[0061] Take 20 ml of the filtrate, keep it at 0 °C for 5 hours, it is still clear and transparent, indicating that the winterization effect is very good.

[0062] As shown in Figure 1 , close the crystallization liquid feed valve V101, filter liquid outlet valve V201, through V102 into 30 °C hot air, so that the solid fat adsorbed in the filter cake is melted, and enters the liquid collection tube through the filter plate, is collected through valve V202, and finally the filtrate (solid fat) 77.9 g is recovered. Finally, the filter cake is blown dry with nitrogen, the filter cover is opened, and the filter cake can be recycled for the next winterization process.

[0063] Example 6

[0064] 2800 g of methyl ester arachidonic acid raw material (content 64.1%) was dissolved at 60 °C for 0.5 hr, and 3.0 g of perlite was added. The temperature was reduced to 2 °C within 60 min, and the temperature was kept for 45 min. 14 g of perlite was added, and stirred for 0.5 hr.

[0065] As shown in Figure 1As shown, the crystallization liquid feed valve V101 of the filter is opened to filter the crystallization liquid containing perlite. The polyunsaturated fatty acid filtrate passes through the filter plate to the liquid collection pipe, and then through the filtrate outlet valve V201. The collected filtrate weighs 2567.6g, with a yield of 91.7%.

[0066] Take 20 ml of the filtrate and keep it at 0℃ for 5 hours. If it remains clear and transparent, it indicates that the winterization effect is very good.

[0067] like Figure 1 As shown, close the crystallization liquid feed valve V101 and the filtrate discharge valve V201. Introduce 100°C superheated steam through V102 to melt the solids adsorbed in the filter cake. The melted solids then pass through the filter plate into the liquid collection pipe and are collected through valve V202. Finally, 203.7g of filtrate (solids) is recovered. The filter cake is then dried with nitrogen. The filter cover is opened, and the recovered filter cake can be reused in the next winterization process.

[0068] Example 7

[0069] 3500g of a mixture of triglyceride-type linolenic acid and linoleic acid (linolenic acid content 12.7%, linoleic acid content 34.5%) was dissolved at 80℃ for 0.45 hours. The mixture was then cooled to winterization crystallization, and the temperature was lowered to -2.5℃ within 45 minutes, and the crystals were kept at this temperature for 45 minutes. 10g of diatomaceous earth, 45g of activated clay, and 60g of perlite were added, and the mixture was stirred for another 0.5 hours until homogeneous.

[0070] like Figure 1 As shown, the crystallization liquid feed valve V101 of the filter is opened to filter the crystallization liquid containing diatomaceous earth, activated clay, and perlite. The polyunsaturated fatty acid filtrate passes through the filter plate to the liquid collection pipe, and then through the filtrate outlet valve V201. The collected filtrate weighs 3143.0g, with a yield of 89.8%.

[0071] Take 20 ml of the filtrate and keep it at 0℃ for 5 hours. If it remains clear and transparent, it indicates that the winterization effect is very good.

[0072] like Figure 1 As shown, close the crystallization liquid feed valve V101 and the filtrate discharge valve V201. Introduce 80°C hot nitrogen through V102 to melt the solids adsorbed in the filter cake. The melted solids then pass through the filter plate into the liquid collection pipe and are collected through valve V202. Finally, 287g of filtrate (solids) is recovered. The filter cake is then dried with nitrogen. The filter cover is opened, and the recovered filter cake can be reused in the next winterization process.

[0073] It should be stated that the above-described invention content and specific embodiments are intended to demonstrate the practical application of the technical solution provided by this invention and should not be construed as limiting the scope of protection of this invention. Those skilled in the art can make various modifications, equivalent substitutions, or improvements within the spirit and principles of this invention.

Claims

1. A method for efficiently separating solid fats from polyunsaturated fatty acid oils, the method comprising the following steps: a) Add a certain amount of inert solid powder as seed crystals to the heated and melted polyunsaturated fatty acid oil, and stir evenly. The inert solid powder is selected from one or a mixture of several of activated carbon, activated clay, diatomaceous earth, and perlite. The polyunsaturated fatty acid oil is selected from one or a mixture of fish oil, algal oil, linoleic acid, conjugated linoleic acid, linolenic acid, and arachidonic acid. The amount of inert solid powder added is 0.1-6.0% (w / w) of the mass of the polyunsaturated fatty acid oil. b) The polyunsaturated fatty acid oil in which the inert solid powder was added in step a) is subjected to cooling crystallization at a temperature of -10℃ to 5℃ to obtain a crystalline mixture; c) The crystalline mixture described in step b) is filtered through a filter to obtain a clear polyunsaturated fatty acid oil and filter cake; d) Introduce hot gas at a temperature of 30-100°C into the filter to melt the solid grease into a liquid state and recover the liquid solid grease; e) Introduce nitrogen gas into the filter to dry any residual grease; and f) Recover the filter cake inert solid powder.

2. The method as described in claim 1, wherein, The polyunsaturated fatty acids exist in the form of methyl esters, ethyl esters, glycerides, or free fatty acids.

3. The method as described in claim 1, wherein, In step a), the melting temperature of the polyunsaturated fatty acid oil is 30-100℃.

4. The method of claim 1, wherein, In step a), the amount of the inert solid powder added is 0.1-1.0% (w / w) of the mass of the polyunsaturated fatty acid oil.

5. The method of claim 1, wherein, In step b), a certain amount of the inert solid powder is added before filtration after cooling and crystallization.

6. The method of claim 5, wherein, In step b), before filtration after cooling and crystallization, the amount of the inert solid powder added is 0.5-6.0% (w / w) of the mass of the polyunsaturated fatty acid oil.

7. The method of claim 1, wherein, In step d), the hot gas is heating steam, heating nitrogen, or heating air; the temperature of the hot gas is 80-100℃.

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