阅读说明：本技术 一种调节婴幼儿配方奶粉脂质组成的结构脂质的制备方法 (Preparation method of structural lipid for regulating lipid composition of infant formula milk powder ) 是由 邹孝强 姜萱 徐林海 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种调节婴幼儿配方奶粉脂质组成的结构脂质的制备方法,其包括如下步骤：在sn-1,3脂肪酸作用下,将棕榈硬脂与植物油来源的不饱和脂肪酸进行酸解,酶解产物中加入丙酮或者正己烷进行两段法湿法分提,脱除饱和油脂以及部分甘油酯,最后脱溶脱酸,获得终产品。本发明所获得的产品质量更高,安全性更好。(The invention discloses a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: under the action of sn-1,3 fatty acid, carrying out acidolysis on palm stearin and unsaturated fatty acid from vegetable oil, adding acetone or n-hexane into an enzymolysis product to carry out two-stage wet fractionation, removing saturated oil and partial glyceride, and finally carrying out desolventizing and deacidification to obtain a final product. The product obtained by the invention has higher quality and better safety.)

1. A preparation method of structural lipid for regulating lipid composition of infant formula milk powder is characterized by comprising the following steps: the method comprises the following steps: firstly, carrying out acidolysis reaction on palm stearin and unsaturated fatty acid from vegetable oil under the action of sn-1,3 fatty acid to obtain an enzymolysis product, then directly adding acetone or n-hexane into the enzymolysis product containing free fatty acid to carry out two-stage wet fractionation, removing saturated oil and partial glyceride by utilizing the synergistic action of the fatty acid and a solvent, and finally carrying out desolventizing deacidification treatment to obtain a final product.

2. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1, wherein: the two-stage wet separation comprises two stages including

In the first stage, palmitic acid and tripalmitin are crystallized to form crystal nuclei;

the second stage crystallizes a portion of the triglycerides containing two saturated fatty acids and a portion of the glycerides.

3. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1, wherein: the acidolysis reaction adopts a packed bed or an intermittent reactor, adopts sn-1, 3-specific Lipase as a catalyst, and the Lipase comprises one or more of Lipzyme RM IM, Lipzyme TL IM, Lipase DF and NS 40086.

4. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1, wherein: the palmitic acid content of the palm stearin is more than 80 percent.

5. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1, wherein: the wet fractionation is that before deacidification, fractionation is directly carried out under the condition of containing free fatty acid, and a solvent used for fractionation is acetone or normal hexane.

6. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1, wherein: the wet fractionation is two-stage fractionation, wherein in the first stage, an enzymolysis product is melted, acetone or normal hexane is added into the enzymolysis product according to the ratio of the enzymolysis product to a solvent being 1:1-4(m/v), the temperature is heated to 50 ℃ to completely melt the grease, the grease is kept for 30min, the temperature is reduced to 9-15 ℃ at the rate of 3-8 ℃ per hour and kept for 3-10 hours, and the palmitic acid and the tripalmitin triglyceride are crystallized to form crystal nuclei.

7. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1 or 6, wherein: the wet fractionation is two-stage fractionation, wherein the second stage is that the temperature of the grease is reduced to 0-7 ℃ at the speed of 2-6 ℃/h, the grease is kept for 5-16 hours, part of triglyceride containing two saturated fatty acids and part of glyceride in the system are crystallized, and liquid oil mixture is obtained through centrifugation or filtration.

8. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1, wherein: the two-stage wet fractionation removes partial glyceride in the process of removing saturated oil.

9. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1, wherein: the final product has a C52 triglyceride content of greater than 55%, OPO and OPL contents of greater than 50%, a total triglyceride content of greater than 95%, and low glycidyl ester and chloropropanol ester contents.

10. The method for preparing structural lipids for regulating lipid composition of infant formula according to claim 1 or 6, wherein: the first stage of wet fractionation is to reduce the temperature to 9 ℃.

Technical Field

The invention relates to the technical field of grease, in particular to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder.

Background

Breast milk contains 3-5% fat, is the primary energy source for infants, and also provides various essential fatty acids and fat-soluble vitamins. The breast milk fat contains many fatty acids, wherein the most saturated fatty acid is palmitic acid, more than 60% of the palmitic acid is located at the sn-2 position of triglyceride, and the sn-1 and sn-3 positions are mainly unsaturated fatty acids, such as oleic acid and linoleic acid. Thus, the predominant triglyceride configuration in breast milk fat is 1, 3-di-unsaturated fatty acid-2-palmitic acid triglyceride (UPU), such as 1, 3-dioleoyl-2-palmitic acid triglyceride (OPO), 1, 3-oleic linoleic acid-2-palmitic acid triglyceride (OPL), and the like. After fat intake in humans, 10% -30% of the fat is first hydrolyzed by the action of duodenal fore-lipase (lingual lipase and gastric lipase) to convert it into sn-1,2 diglycerides. In the small intestine, most triglycerides are hydrolyzed by pancreatic lipase into sn-2 monoglycerides and free fatty acids under the action of bile salts. sn-2 monoglycerides are directly absorbed by small intestinal epithelial cells, and fatty acid absorption is related to their unsaturation and chain length. Long chain saturated fatty acids tend to form poorly absorbed soaps with calcium or magnesium ions, resulting in energy and calcium loss and other side effects such as constipation. Therefore, the special triglyceride structure of the breast milk fat determines the high efficiency of breast milk fat absorption, and simultaneously avoids the occurrence of constipation of infants and the loss of calcium ions in the body.

In contrast to breast milk fat, most infant formulas contain a majority of fats based on vegetable oils, with the palmitic acid in the triglycerides of vegetable oils being mostly distributed in the sn-1 and sn-3 positions, and the sn-2 position is mostly unsaturated fatty acid. To regulate the fat structure of breast milk, researchers have developed breast milk substitute fats as fat component additives for infant formulas to make the formula similar to breast milk fat in fatty acid profile. The state also has come out of the national food safety standard GB30604-2015 food nutrition enhancer 1, 3-dioleate-2-palmitic acid triglyceride in 2015, wherein the production method and various indexes are specified. At present, OPO structural fat is added to most high-end infant formula milk powder at home and abroad. However, due to the patent barriers, the only manufacturers capable of producing OPO products industrially are Danish Advanced fats and oils (Advanced Lipids) and Loders Croklaan (Loders Croklaan) of Malaysia, with product names of eachAndno enterprises capable of producing OPO structure fat exist in China. This situationIs extremely disadvantageous for developing the formula milk powder suitable for Chinese infants.

China is greatly different from foreign breast milk fat in that the Chinese breast milk fat contains a large amount of OPL in addition to OPO. Therefore, a structural fat suitable for chinese infant formula should be a structural fat comprising OPO and OPL. For the indexes of national food safety standards GB30604-2015, the index of OPO content is C52 triglyceride, and the detection method is high temperature gas chromatography. The C52 triglyceride detected by this method is actually a triglyceride containing OPO, OPL, LPL, etc., having an acyl group with a carbon number of 52. Thus, the standard index C52 triglyceride actually contains UPU. Currently, OPO is mainly obtained by catalyzing acidolysis reaction of oleic acid and palm stearin by lipase. However, the content of the target substance in the product is relatively low due to lack of subsequent treatment of the acidolysis product, and the harmful substances generated during the process are difficult to control.

Disclosure of Invention

This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.

The present invention has been made in view of the above and/or problems associated with the prior art structured lipid products for modulating the lipid composition of infant formula.

Therefore, one of the objectives of the present invention is to provide a method for preparing structural lipid for regulating lipid composition of infant formula, which overcomes the disadvantages of the existing methods for preparing structural lipid for regulating lipid composition of infant formula.

To solve the above technical problem, according to an aspect of the present invention, the present invention provides the following technical solutions: a preparation method of structural lipid for regulating lipid composition of infant formula milk powder comprises the following steps: firstly, carrying out acidolysis reaction on palm stearin and unsaturated fatty acid from vegetable oil under the action of sn-1,3 fatty acid to obtain an enzymolysis product, then directly adding acetone or n-hexane into the enzymolysis product containing free fatty acid to carry out two-stage wet fractionation, removing saturated oil and partial glyceride by utilizing the synergistic action of the fatty acid and a solvent, and finally carrying out desolventizing deacidification treatment to obtain a final product.

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: the two-stage wet separation comprises two stages, which comprise

In the first stage, palmitic acid and tripalmitin are crystallized to form crystal nuclei;

the second stage crystallizes a portion of the triglycerides containing two saturated fatty acids and a portion of the glycerides.

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: the acidolysis reaction adopts a packed bed or an intermittent reactor, adopts sn-1, 3-specific Lipase as a catalyst, and the Lipase comprises one or more of Lipzyme RM IM, Lipzyme TL IM, Lipase DF and NS 40086.

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: the palmitic acid content of the palm stearin is more than 80 percent.

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: wet fractionation is to directly perform fractionation under the condition of containing free fatty acid before deacidification, wherein the solvent used for fractionation is acetone or n-hexane.

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: wet fractionation is two-stage fractionation, wherein in the first stage, an enzymolysis product is melted, acetone or normal hexane is added into the enzymolysis product according to the ratio of the enzymolysis product to a solvent being 1:1-4(m/v), the temperature is heated to 50 ℃ to completely dissolve grease, the temperature is kept for 30min, the temperature is reduced to 9-15 ℃ at the rate of 3-8 ℃ per hour, and the temperature is kept for 3-10 hours to crystallize palmitic acid and tripalmitoyl triglyceride to form crystal nuclei.

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: wet fractionation is two-stage fractionation, wherein in the second stage, the temperature of the grease is reduced to 0-7 ℃ at the speed of 2-6 ℃/h, the grease is kept for 5-16 hours, part of triglyceride containing two saturated fatty acids and part of glyceride in the system are crystallized, and liquid oil mixture is obtained through centrifugation or filtration.

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: the two-stage wet fractionation removes partial glyceride in the process of removing saturated oil.

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: the final product has C52 triglyceride content of more than 55%, OPO and OPL content of more than 50%, total triglyceride content of more than 95%, and low content of glycidyl ester and chloropropanol ester

The invention relates to a preparation method of structural lipid for regulating lipid composition of infant formula milk powder, which comprises the following steps: the first stage of wet fractionation is to lower the temperature to 9 DEG C

This patent technique adopts sn-1,3 lipase catalysis palm stearin and vegetable oil sourced unsaturated fatty acid at first to carry out the acidolysis reaction and obtains the enzymolysis product, before the deacidification, directly adds organic solvent to the enzymolysis product that contains free fatty acid and carries out two sections wet process and carry out the branch and carry out, utilizes the synergistic effect of solvent and unsaturated fatty acid to improve the selectivity of branch and carry out the triglyceride, desorption saturated oil and partial glyceride, carries out the desolventizing deacidification again at last. Compared with other existing processes, the product obtained by the process has higher quality and better safety. The steps actually adopted by the invention comprise the following steps with practical effects: 1. through the organic solvent segmentation fractionation containing fatty acid, palmitic acid and tripalmitin are crystallized through the first section to form a crystal nucleus, so that the subsequent crystallization containing two saturated fatty acid triglycerides and partial glyceride is facilitated, the selectivity of the triglycerides in the fractionation process is improved, and the content of target substances in the product is improved. 2. The acidolysis product has relatively high fatty acid content, and can be used as a solvent and an organic solvent for synergistic effect in the triglyceride fractionation process, so that the selectivity of triglyceride fractionation is improved, and the product quality is improved; 3. before the fatty acid is removed by reduced pressure distillation, an organic solvent containing free fatty acid is adopted for fractionation, and partial glyceride in a system is removed to the greatest extent, so that the generation of harmful substances such as glycidyl ester and chloropropanol ester in the process of removing the fatty acid by reduced pressure distillation is avoided, and the safety of the product is improved; 4. the obtained product has high triglyceride content and low partial glyceride content, and is beneficial to increasing the oxidation stability of the grease and prolonging the shelf life of the product.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, specific embodiments thereof are described in detail below with reference to examples of the specification.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

Example 1

Selecting palm stearin with palmitic acid content of 91.2% and sn-2 palmitic acid content of 84.4% as a starting material, using fatty acid from high-oleic sunflower oil as an acyl donor, mixing the high-oleic sunflower oil fatty acid with the palm stearin according to a substrate molar ratio of 8:1, heating the mixed oil to 60 ℃, and keeping for 20min to completely dissolve the mixed oil. The method comprises the steps of adopting a packed bed as a reactor, introducing nitrogen into the packed bed to replace air, introducing mixed grease into the packed bed reactor, keeping the temperature of the packed bed at 60 ℃, keeping the retention time of the grease in the packed bed at 3 hours, and obtaining an acidolysis product after the reaction is finished. Removing possible impurities in the mixed oil through centrifugation or filtration, directly adding acetone into an enzymolysis product, wherein the ratio of the enzymolysis product to the acetone is 1:2(m/v), heating to 50 ℃ to completely dissolve the oil, keeping the temperature for 30min, reducing the temperature to 11 ℃ at the speed of 5 ℃/h, keeping the temperature for 3h to crystallize palmitic acid and saturated triglyceride to form crystal nuclei, reducing the temperature to 3 ℃ according to 2 ℃/h to crystallize partial triglyceride and partial glyceride containing two saturated fatty acids in the system, keeping the temperature for 8h, and rotating the speed in the fractionation process to 30 r/min. Removing solid fat in the system by filtering or centrifuging to obtain liquid oil solution, removing the solvent by reduced pressure distillation, and removing fatty acid to obtain the final product 1.

Example 2

Selecting palm stearin with palmitic acid content of 82.4% and sn-2 palmitic acid content of 75.5% as a starting material, using high oleic peanut oil derived fatty acid as an acyl donor, mixing the high oleic peanut oil fatty acid with the palm stearin according to a substrate molar ratio of 4:1, heating the mixed oil to 60 ℃, and keeping for 20min to completely dissolve the mixed oil. The method comprises the steps of adopting a packed bed as a reactor, introducing nitrogen into the packed bed to replace air, introducing mixed grease into the packed bed reactor, keeping the temperature of the packed bed at 50 ℃, keeping the retention time of the grease in the packed bed at 6 hours, and obtaining an acidolysis product after the reaction is finished. Removing possible impurities in the mixed oil through centrifugation or filtration, adding acetone into an enzymolysis product, wherein the ratio of the enzymolysis product to the acetone is 1:1(m/v), heating to 50 ℃ to completely dissolve the oil, keeping the temperature for 30min, reducing the temperature to 15 ℃ at the speed of 3 ℃/h, keeping the temperature for 8h to crystallize palmitic acid and saturated triglyceride to form crystal nuclei, reducing the temperature to 7 ℃ according to 3 ℃/h to crystallize partial triglyceride and partial glyceride containing two saturated fatty acids in the system, keeping the temperature for 10h, and rotating the rotating speed in the fractionation process to be 60 r/min. Removing solid fat in the system by filtering or centrifuging to obtain liquid oil solution, removing solvent by reduced pressure distillation, and removing fatty acid to obtain final product 2.

Example 3

Selecting palm stearin with palmitic acid content of 91.2% and sn-2 palmitic acid content of 84.4% as a starting material, using fatty acid derived from high oleic rapeseed oil as an acyl donor, mixing the high oleic rapeseed oil fatty acid and the palm stearin according to a substrate molar ratio of 12:1, and heating the mixed oil to 60 ℃ to completely melt the mixed oil. Adding the mixed oil into a batch reactor, introducing nitrogen into the batch reactor, selecting NS40086 as a catalyst, adding 10% of lipase, reacting at 50 ℃ for 12 hours at a stirring speed of 600 revolutions per minute, and obtaining an acidolysis product after the reaction. Removing lipase by centrifugation or filtration, adding normal hexane into an enzymolysis product, wherein the ratio of the enzymolysis product to the normal hexane is 1:4(m/v), heating to 50 ℃ to completely dissolve grease, keeping for 30min, reducing the temperature to 9 ℃ at the speed of 8 ℃ per hour, keeping for 5h at the temperature to crystallize palmitic acid and saturated triglyceride to form crystal nuclei, reducing the temperature to 0 ℃ according to 6 ℃ per hour to crystallize partial triglyceride containing two saturated fatty acids and partial glyceride in a system, keeping for 12h at the temperature, and rotating at 40 r/min in the fractionation process. Removing solid fat in the system by filtering or centrifuging to obtain liquid oil solution, removing solvent by reduced pressure distillation, and removing fatty acid to obtain final product 3.

The main criteria of the final products obtained in examples 1-3 are shown in Table 1.

TABLE 1 Main indices of the final product

Index (I)	End product 1	End product 2	End product 3
				C52 Triglycerides	67.4	57.6	72.3
OPO(％)	52.1	41.6	47.5
				OPL(％)	10.6	9.3	16.2
PPP(％)	67.4	57.6	72.3
				Triglyceride (%)	97.7	97.4	97.0
Diglyceride (%)	1.59	2.18	2.37
				Monoglyceride (%)	0.73	0.42	0.65
Glycidyl ester (mg/kg)	0.13	0.25	0.22
				Chloropropanol ester (mg/kg)	0.28	0.41	0.36

Example 4

Selecting palm stearin with palmitic acid content of 91.2% and sn-2 palmitic acid content of 84.4% as a starting material, taking tea seed oil derived fatty acid as an acyl donor, mixing the tea seed oil fatty acid and the palm stearin according to a substrate molar ratio of 10:1, heating the mixed oil to 60 ℃, and completely dissolving the mixed oil. The method comprises the steps of adopting a packed bed as a reactor, introducing nitrogen into the packed bed to replace air, introducing mixed grease into the packed bed reactor, keeping the temperature of the packed bed reactor at 60 ℃, enabling the grease to stay in the packed bed for 2 hours, and obtaining an acidolysis product after the reaction is finished. Removing possible impurities in the mixed oil through centrifugation or filtration, adding acetone into an enzymolysis product, wherein the ratio of the enzymolysis product to the acetone is 1:3(m/v), heating to 50 ℃ to completely dissolve the oil, keeping the temperature for 30min, reducing the temperature to 10 ℃ at the speed of 3 ℃/h, keeping the temperature for 8h to crystallize palmitic acid and saturated triglyceride to form crystal nuclei, reducing the temperature to 3 ℃ according to 3 ℃/h to crystallize the triglyceride containing two saturated fatty acids in the system, keeping the temperature for 16h, and rotating the speed in the fractionation process at 30 revolutions per minute. Removing solid fat in the system by filtering or centrifuging to obtain liquid oil solution, removing solvent by reduced pressure distillation, and removing fatty acid to obtain final product 4.

Example 5

Selecting palm stearin with palmitic acid content of 82.4% and sn-2 palmitic acid content of 75.5% as a starting material, mixed fatty acid derived from rapeseed oil as an acyl donor, mixing the rapeseed oil fatty acid and the palm stearin according to a substrate molar ratio of 12:1, and heating the mixed oil to 60 ℃ to completely melt the mixed oil. The method comprises the steps of adopting a packed bed as a reactor, introducing nitrogen into the packed bed to replace air, introducing mixed grease into the packed bed reactor, keeping the temperature of the packed bed reactor at 55 ℃, keeping the grease in the packed bed for 5 hours, and obtaining an acidolysis product after the reaction is finished. Removing possible impurities in the mixed oil through centrifugation or filtration, adding normal hexane into an enzymolysis product, wherein the ratio of the enzymolysis product to the normal hexane is 1:1(m/v), heating to 50 ℃ to completely dissolve the oil, keeping the temperature for 30min, reducing the temperature to 14 ℃ at the speed of 6 ℃/h, keeping the temperature for 4h to crystallize palmitic acid and saturated triglyceride to form crystal nuclei, reducing the temperature to 7 ℃ according to 5 ℃/h to crystallize partial triglyceride and partial glyceride containing two saturated fatty acids in the system, keeping the temperature for 8h, and rotating the rotating speed in the fractionation process to be 50 r/min. Removing solid fat in the system by filtering or centrifuging to obtain liquid oil solution, removing solvent by reduced pressure distillation, and removing fatty acid to obtain final product 5.

Example 6

Selecting palm stearin with palmitic acid content of 91.2% and sn-2 palmitic acid content of 84.4% as a starting material, and mixed fatty acid derived from tea seed oil and sunflower seed oil as an acyl donor, wherein the molar ratio of the tea seed oil to the sunflower seed oil fatty acid is 3:1, mixing the rapeseed oil fatty acid and the palm stearin according to the substrate molar ratio of 8:1, and heating the temperature of the mixed oil to 60 ℃ to completely dissolve the mixed oil. Adding the mixed grease into a batch reactor, introducing nitrogen into the batch reactor, selecting Lipozyme RM IM as a catalyst, adding 6% of lipase, reacting at 60 ℃ for 8 hours at a stirring speed of 400 r/min, and obtaining an acidolysis product after the reaction is finished. Removing lipase from mixed oil by centrifugation or filtration, adding acetone into an enzymolysis product, wherein the ratio of the enzymolysis product to the acetone is 1:2(m/v), heating to 50 ℃ to completely dissolve the oil, keeping the temperature for 30min, reducing the temperature to 12 ℃ at the speed of 8 ℃/h, keeping the temperature for 10h to crystallize palmitic acid and saturated triglyceride to form a crystal nucleus, reducing the temperature to 2 ℃ according to 6 ℃/h to crystallize partial triglyceride containing two saturated fatty acids and partial glyceride in the system, keeping the temperature for 5h, and rotating the rotating speed in the fractionation process to 40 r/min. Removing solid fat in the system by filtering or centrifuging to obtain liquid oil solution, removing solvent by reduced pressure distillation, and removing fatty acid to obtain final product 6.

Example 7

Selecting palm stearin with palmitic acid content of 91.2% and sn-2 palmitic acid content of 84.4% as a starting material, rapeseed oil and soybean oil-derived fatty acid as acyl donors, wherein the molar ratio of the rapeseed oil to the soybean oil fatty acid is 2:1, mixing the rapeseed oil fatty acid and the palm stearin according to the substrate molar ratio of 6:1, and heating the temperature of the mixed oil to 60 ℃ to completely dissolve the mixed oil. The method comprises the steps of adopting a packed bed as a reactor, introducing nitrogen into the packed bed to replace air, introducing mixed grease into the packed bed reactor, keeping the temperature of the packed bed reactor at 50 ℃, keeping the grease in the packed bed for 5 hours, and obtaining an acidolysis product after the reaction is finished. Removing possible impurities in the mixed oil through centrifugation or filtration, adding acetone into an enzymolysis product, wherein the ratio of the enzymolysis product to the acetone is 1:4(m/v), heating to 50 ℃ to completely dissolve the oil, keeping the temperature for 30min, reducing the temperature to 9 ℃ at the speed of 5 ℃/h, keeping the temperature for 6h to crystallize palmitic acid and saturated triglyceride to form crystal nuclei, reducing the temperature to 0 ℃ according to 4 ℃/h to crystallize partial triglyceride and partial glyceride containing two saturated fatty acids in the system, keeping the temperature for 12h, and rotating the speed in the fractionation process to be 30 r/min. Removing solid fat in the system by filtering or centrifuging to obtain liquid oil solution, removing solvent by reduced pressure distillation, and removing fatty acid to obtain final product 7.

The main criteria of the final products obtained in examples 4-7 are shown in Table 2.

TABLE 2 Main indices of the final product

Index (I)	End product 4	End product 5	End product 6	End product 7
					C52 Triglycerides	68.5	61.6	66.7	64.3
OPO(％)	36.6	33.5	27.5	22.5
					OPL(％)	24.7	20.6	28.8	29.8
PPP(％)	1.1	0.8	1.3	1.5
					Triglyceride (%)	98.2	97.3	97.1	97.3
Diglyceride (%)	1.26	1.84	2.13	2.13
					Monoglyceride (%)	0.52	0.82	0.74	0.58
Glycidyl ester (mg/kg)	0.11	0.18	0.21	0.28
					Chloropropanol ester (mg/kg)	0.24	0.31	0.36	0.47

Comparative example 1

After the acidolysis reaction was performed according to the reaction conditions of examples 1,2, 6 and 7 to obtain an acidolysis product, the fatty acid was first removed by distillation under reduced pressure to obtain an intermediate product, and then separated by wet fractionation to obtain comparative products 1,2, 6 and 7, the main indices of which are shown in table 3.

TABLE 3 comparison of the main indices of the end products

After the acidolysis reaction, directly adding an organic solvent, and carrying out wet segmentation separation under the condition of containing fatty acid, wherein in the first stage, palmitic acid and tripalmitin with higher melting points are crystallized to form crystal nuclei, so that the crystallization of triglyceride containing two saturated fatty acids and partial glyceride in the second stage of separation is facilitated, the selectivity of triglyceride in the separation process is improved, and the content of OPO and OPL in the product is improved; the wet fractionation is carried out before the fatty acid is removed by reduced pressure distillation, so that on one hand, the solubility of unsaturated fatty acid is utilized, the fatty acid and the organic solvent are cooperated to improve the fractionation effect, and on the other hand, partial glyceride is removed as much as possible in the fractionation process, thereby reducing the generation of harmful substances in the deacidification stage.

Due to the fact that partial glycerides have a certain degree of amphiphilicity, they are present in the oil predominantly in the form of micelles. Fats and oils are hydrophobic and have a low water content, but the presence of amphiphilic substances increases the solubility of water in fats and oils. The presence of water also causes substances having an oxygen-promoting action, such as metal ions, to be accumulated in the oil or fat, and thus this is also a main site of the oxidation reaction of the oil or fat. After the grease is subjected to oxidation reaction, peroxide is generated, and the peroxide also has amphiphilicity and is cracked to form free radicals, so that the oxidation of the grease is further accelerated. Therefore, the higher the content of the amphiphilic substance in the fat or oil, the poorer the oxidation stability of the fat or oil.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.