Product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipid and preparation method thereof
阅读说明：本技术 一种富含1,3-不饱和-2-饱和脂肪酸结构脂的产品及其制备方法 (Product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipid and preparation method thereof ) 是由 邹孝强 李亚茹 徐秀丽 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种富含1,3-不饱和-2-饱和脂肪酸结构脂的产品及其制备方法,以高于母乳脂肪sn-2位饱和脂肪酸组成5-30％为依据,以棕榈硬脂为原料,通过油脂混合模型计算,调节sn-2位饱和脂肪酸组成；再利用酶催化酸解反应脂肪酸平衡模型预测酸解混合油脂所需的脂肪酸比例,并通过两步酸解反应耦合低温程序分提方法,获得富含1,3-不饱和2-饱和脂肪酸结构脂的产品,向所得产品外源添加5-30％油脂时,sn-2饱和脂肪酸组成仍在母乳脂肪范围内。(The invention discloses a product rich in 1, 3-unsaturated-2-saturated fatty acid structural fat and a preparation method thereof, which takes saturated fatty acid composition 5-30% higher than sn-2 site of breast milk fat as basis, takes palm stearin as raw material, and adjusts the sn-2 site saturated fatty acid composition through calculation of a fat mixing model; and then predicting the proportion of fatty acid required by acidolysis of mixed oil by using an enzyme-catalyzed acidolysis reaction fatty acid balance model, obtaining a product rich in 1, 3-unsaturated 2-saturated fatty acid structural fat by a two-step acidolysis reaction coupled low-temperature program fractionation method, and adding 5-30% of oil to the obtained product, wherein the composition of the sn-2 saturated fatty acid is still in the range of breast milk fat.)
1. A method for preparing a product rich in 1, 3-unsaturated-2-saturated fatty acid structured fat is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
mixing the grease based on the model;
carrying out acidolysis by a primary enzyme method;
separating and extracting palmitic acid at a low temperature;
secondary enzymatic acidolysis;
distilling under reduced pressure to remove free fatty acid to obtain the product.
2. The method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipids according to claim 1, wherein: the mixing of the grease is carried out, wherein,
mixing the oil according to the range of 5-30% higher than the sn-2 saturated fatty acid of breast milk fat; wherein, the oil mixing proportion is obtained by calculating an oil physical mixing model.
3. The method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipids according to claim 2, wherein: the physical mixing model of the grease comprises,
according to the fatty acid composition and distribution of the oil, establishing a calculation model of the sn-2 fatty acid composition of the oil:
wherein sn-2 FA% is sn-2 fatty acid composition of mixed oil, and Y1(sn-2)And Yi(sn-2)Respectively the content of each fatty acid on the sn-2 position of the palm stearin and the selected oil, and Xi is the molar ratio of the selected oil to the palm stearin;
wherein, FA% is fatty acid composition of the mixed oil, sn-1,3 FA% is sn-1,3 fatty acid composition of the mixed oil, Y1 and Yi are the contents of each fatty acid of the palm stearin and the selected oil respectively;
by setting XiAccording to the formula, the fatty acid composition and distribution in the mixed system can be calculated;
establishing an inequality according to the composition characteristics of the sn-2 fatty acid of the breast milk fat, and calculating to obtain the addition range of each oil in the sn-2 fatty acid range of the breast milk fat;
finally, the total fatty acid composition and the sn-1,3 fatty acid composition are calculated by the formulas 2 and 3.
4. The method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipids according to claim 1, wherein: in the enzymatic acidolysis, the fatty acid proportion is obtained by predicting an acidolysis reaction fatty acid equilibrium model;
the acidolysis reaction fatty acid equilibrium model prediction comprises,
in the reaction system, the content of triglyceride is m, the content of fatty acid is h, in the reaction process, the used lipase is sn-1,3 position specific lipase, and the fatty acid accords with random distribution on the sn-1,3 position;
in the whole reaction system, the fatty acid types are defined as n, and different fatty acids are defined as XiThe acyl transfer is controlled by using the reaction conditions, and the change amount of the sn-2 fatty acid is small, so that the change of the sn-2 fatty acid can be ignored;
in the system, the fatty acids participating in the reaction are mainly triglyceride sn-1,3 fatty acid and added free fatty acid;
for fatty acid X alonei"Yigan" medicineX in sn-1,3 position of an oil triesteriThe mole percent of fatty acids can be expressed as Msn-1/-3XiFree fatty acid XiCan be expressed as MXi；
When the system reaches the reaction equilibrium, according to the random distribution principle, XiThe fatty acid reaction equilibrium is at the sn-1,3 content (sn-1/3X) of triglyceridei) Can be expressed as:
due to the fact thatTherefore, the temperature of the molten metal is controlled,the model can be further simplified as:
let h/m be S, i.e. the molar ratio of free fatty acids to triglycerides is S: 1, therefore, the sn-1,3 content of triglycerides at the equilibrium of the Xi fatty acid reaction can be further reduced to:
wherein M issn-1/3XiIs XiThe molar percentage of fatty acids at the sn-1,3 position of the triglyceride; mXiAs free fatty acid XiMole percent of (c); s is the molar ratio of free fatty acids to triglycerides.
5. The method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipids according to claim 1 or 4, wherein: in the acidolysis reaction, the used Lipase is sn-1, 3-position Lipase, including Lipzyme RM IM, Lipzyme TL IM, Lipase DF and NS 40086.
6. The method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structured fat according to any one of claims 1 to 4, wherein: in the acidolysis reaction, the acyl donor is fatty acid derived from vegetable oil rich in oleic acid or linoleic acid, and comprises one or more of high-oleic-acid soybean oil, high-oleic-acid rapeseed oil, high-oleic-acid peanut oil, soybean oil and rapeseed oil.
7. The method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipids according to claim 6, wherein: the acidolysis by the primary enzyme method is carried out in a packed bed reactor, and the conditions of the one-step acidolysis reaction are as follows: heating the mixed grease to 55-65 ℃, keeping the temperature for 20-45 min, introducing the mixture into a packed bed reactor after the mixture is completely melted, wherein the reaction temperature is 50-60 ℃, and the reaction time is 1-4 h.
8. The method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipids according to claim 1, wherein: the low-temperature procedure is used for fractionation of palmitic acid, and the conditions are as follows:
heating the grease to 55-70 ℃ and maintaining for 20-40 min, completely melting, reducing the temperature to 25-35 ℃ at the speed of 4-15 ℃/h, growing crystals for 3-10 h, and filtering or centrifugally separating solid fat after fractionation and crystallization to obtain liquid oil.
9. The method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipids according to claim 6, wherein: the secondary enzymatic acidolysis has the reaction conditions that:
heating the fractionated liquid oil serving as a raw material to 50-60 ℃, keeping the temperature for 15-30 min, and introducing into a packed bed reactor, wherein the reaction temperature is 45-60 ℃, and the reaction time is 1-4 h;
the product is obtained by separating possible impurities by centrifugation or filtration and removing the free fatty acids by distillation under reduced pressure.
10. The product obtained by the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural lipids according to any one of claims 1 to 9, wherein:
when 5-30% of oil is added to the obtained product, the composition of the sn-2 saturated fatty acid is in the range of breast milk fat.
Technical Field
The invention belongs to the technical field of grease, and particularly relates to a product rich in 1, 3-unsaturated-2-saturated fatty acid structured grease and a preparation method thereof.
Background
The fat in breast milk accounts for 3-5% of the total milk, and provides more than 50% of energy for infants. The content of triglyceride in breast milk lipid is above 98%. The triglyceride contains various fatty acids including medium-chain fatty acids, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, odd-chain fatty acids, branched fatty acids, etc. Among these fatty acids, the fatty acids having a content of more than 1% are oleic acid, palmitic acid, linoleic acid, stearic acid, myristic acid, lauric acid, and palmitoleic acid.
The fatty acid distribution of triglycerides in breast milk lipids is unique, with most saturated fatty acids distributed at the sn-2 position of triglycerides and other unsaturated fatty acids distributed primarily at the sn-1,3 positions. The most abundant triglycerides in human milk fat are 1, 3-unsaturated 2-saturated fatty acid triglycerides, such as OPO and OPL. The triglyceride with the structure has close relationship with the digestion, absorption and metabolism of infants. After ingestion, fat is first hydrolyzed 10% -30% by the action of duodenal pre-lipase (lingual lipase and gastric lipase), converting 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 monoglyceride can be directly absorbed by small intestine epithelial cells, and long-chain saturated fatty acid is easy to form soap which is difficult to absorb with calcium or magnesium ions, so that energy and calcium are lost, and other side effects such as constipation and the like are caused.
Therefore, the location of most saturated fatty acids in breast milk lipids at the sn-2 position can avoid these side effects, facilitating energy use by infants. Meanwhile, absorbed sn-2 monoglyceride is re-esterified in small intestine epithelial cells to generate triglyceride, and finally transported and utilized, and about 70% of sn-2 fatty acid is kept unchanged in the process. Therefore, the composition of sn-2 fatty acids is closely related to the metabolism of triglycerides.
In nature, the content of sn-1,3 unsaturated and sn-2 saturated fatty acid triglyceride is very low, so that the synthesis of 1, 3-unsaturated-2-saturated fatty acid triglyceride with the sn-2 saturated fatty acid consistent with breast milk fat as an additive for regulating the triglyceride structure of the infant formula milk powder has important significance. However, 1, 3-unsaturated sn-2-saturated fatty acid triglycerides are only one type of triglycerides in breast milk fat, and when formula milk is added, 5-30% of other oils and fats are usually added to adjust the fatty acid composition, so that it is difficult to ensure that the sn-2 saturated fatty acid composition is within the range of breast milk fat.
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 keeping in mind the above and/or other problems occurring in the prior art.
Therefore, the invention aims to overcome the defects in the prior art and provide a preparation method of a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester.
In order to solve the technical problems, the invention provides the following technical scheme: a method for preparing a product rich in 1, 3-unsaturated-2-saturated fatty acid structured fat comprises mixing the fat based on a model; carrying out acidolysis by a primary enzyme method; separating and extracting palmitic acid at a low temperature; secondary enzymatic acidolysis; distilling under reduced pressure to remove free fatty acid to obtain the product.
As a preferable embodiment of the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester according to the present invention, wherein: mixing the oil, wherein the oil is mixed according to the range of 5-30% higher than the sn-2 saturated fatty acid of breast milk fat; wherein, the oil mixing proportion is obtained by calculating an oil physical mixing model.
As a preferable embodiment of the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester according to the present invention, wherein: the physical mixing model of the grease comprises,
according to the fatty acid composition and distribution of the oil, establishing a calculation model of the sn-2 fatty acid composition of the oil:
wherein sn-2 FA% is sn-2 fatty acid composition of mixed oil, and Y1(sn-2)And Yi(sn-2)Respectively the content of each fatty acid on the sn-2 position of the palm stearin and the selected oil, and Xi is the molar ratio of the selected oil to the palm stearin;
wherein, FA% is fatty acid composition of the mixed oil, sn-1,3 FA% is sn-1,3 fatty acid composition of the mixed oil, Y1 and Yi are the contents of each fatty acid of the palm stearin and the selected oil respectively;
by setting XiAccording to the formula, the fatty acid composition and distribution in the mixed system can be calculated;
establishing an inequality according to the composition characteristics of the sn-2 fatty acid of the breast milk fat, and calculating to obtain the addition range of each oil in the sn-2 fatty acid range of the breast milk fat;
finally, the total fatty acid composition and the sn-1,3 fatty acid composition are calculated by the formulas 2 and 3.
As a preferable embodiment of the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester according to the present invention, wherein: in the enzymatic acidolysis, the fatty acid proportion is obtained by predicting an acidolysis reaction fatty acid equilibrium model;
the acidolysis reaction fatty acid equilibrium model prediction comprises,
in the reaction system, the content of triglyceride is m, the content of fatty acid is h, in the reaction process, the used lipase is sn-1,3 position specific lipase, and the fatty acid accords with random distribution on the sn-1,3 position;
in the whole reaction system, the fatty acid types are defined as n, and different fatty acids are defined as XiThe acyl transfer is controlled by using the reaction conditions, and the change amount of the sn-2 fatty acid is small, so that the change of the sn-2 fatty acid can be ignored;
in the system, the fatty acids participating in the reaction are mainly triglyceride sn-1,3 fatty acid and added free fatty acid;
for fatty acid X aloneiX in sn-1,3 position of triglycerideiThe mole percent of fatty acids can be expressed as Msn-1/-3XiFree fatty acid XiCan be expressed as MXi；
When the system reaches the reaction equilibrium, according to the random distribution principle, XiThe fatty acid reaction equilibrium is at the sn-1,3 content (sn-1/3X) of triglyceridei) Can be expressed as:
due to the fact thatTherefore, the temperature of the molten metal is controlled,the model can be further simplified as:
let h/m be S, i.e. the molar ratio of free fatty acids to triglycerides is S: 1, therefore, the sn-1,3 content of triglycerides at the equilibrium of the Xi fatty acid reaction can be further reduced to:
wherein M issn-1/3XiIs XiThe molar percentage of fatty acids at the sn-1,3 position of the triglyceride; mXiAs free fatty acid XiMole percent of (c); s is the molar ratio of free fatty acids to triglycerides.
As a preferable embodiment of the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester according to the present invention, wherein: in the acidolysis reaction, the used Lipase is sn-1, 3-position Lipase, including Lipzyme RM IM, Lipzyme TL IM, Lipase DF and NS 40086.
As a preferable embodiment of the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester according to the present invention, wherein: in the acidolysis reaction, the acyl donor is fatty acid derived from vegetable oil rich in oleic acid or linoleic acid, and comprises one or more of high-oleic-acid soybean oil, high-oleic-acid rapeseed oil, high-oleic-acid peanut oil, soybean oil and rapeseed oil.
As a preferable embodiment of the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester according to the present invention, wherein: the acidolysis by the primary enzyme method is carried out in a packed bed reactor, and the conditions of the one-step acidolysis reaction are as follows: heating the mixed grease to 55-65 ℃, keeping the temperature for 20-45 min, introducing the mixture into a packed bed reactor after the mixture is completely melted, wherein the reaction temperature is 50-60 ℃, and the reaction time is 1-4 h.
As a preferable embodiment of the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester according to the present invention, wherein: the low-temperature procedure is used for fractionation of palmitic acid, and the conditions are as follows:
heating the grease to 55-70 ℃ and maintaining for 20-40 min, completely melting, reducing the temperature to 25-35 ℃ at the speed of 4-15 ℃/h, growing crystals for 3-10 h, and filtering or centrifugally separating solid fat after fractionation and crystallization to obtain liquid oil.
As a preferable embodiment of the method for producing a product rich in 1, 3-unsaturated-2-saturated fatty acid structural ester according to the present invention, wherein: the secondary enzymatic acidolysis has the reaction conditions that:
heating the fractionated liquid oil serving as a raw material to 50-60 ℃, keeping the temperature for 15-30 min, and introducing into a packed bed reactor, wherein the reaction temperature is 45-60 ℃, and the reaction time is 1-4 h;
the product is obtained by separating possible impurities by centrifugation or filtration and removing the free fatty acids by distillation under reduced pressure.
The invention further aims to overcome the defects in the prior art and provide a product prepared by the preparation method of the product rich in 1, 3-unsaturated-2-saturated fatty acid structural fat, wherein when 5-30% of oil is added externally to the obtained product, the composition of the sn-2 saturated fatty acid is in the range of breast milk fat.
The invention has the beneficial effects that:
according to the method, other oil needs to be added in the simulated breast milk fat composition, and the proportion of the added oil is calculated through an oil mixing model on the basis of the range of 5-30% higher than the sn-2 saturated fatty acid of the breast milk fat; predicting the proportion of fatty acid by using an acidolysis reaction fatty acid balance model, performing fractionation by using a two-step enzymatic acidolysis coupling low-temperature procedure to obtain a product rich in 1, 3-unsaturated 2-saturated fatty acid structural lipid, and adding 5-30% of oil to the obtained product, wherein the composition of the sn-2 saturated fatty acid is still in the range of breast milk fat;
according to the invention, by utilizing the melting point difference, the palmitic acid in the system is removed by utilizing the melting point difference after the first-step acidolysis reaction, the unsaturated degree of the free fatty acid is increased, and then the second-step acidolysis reaction is carried out, so that the content of the sn-1,3 unsaturated fatty acid of the product is increased, the utilization rate of the free fatty acid is improved, and the energy consumption is greatly reduced.
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.
The fatty acid profile of the coconut oil and palm kernel oil of the present invention is shown in table 1.
TABLE 1 fatty acid profile of coconut oil and palm kernel oil
Coconut oil
Palm kernel oil
General assembly
sn-2
General assembly
sn-2
C6:0
0.24
0.05
0.335
0.2
0.06
0.27
C8:0
5.71
1.43
7.85
2.99
1.78
3.595
C10:0
5.56
3.46
6.61
3.17
2.89
3.31
C12:0
47.7
60.02
41.54
47.14
61.38
40.02
C14:0
19.3
22.15
17.875
16.39
18.98
15.095
C16:0
9.67
5.06
11.975
8.83
4.69
10.9
C18:0
3
0.87
4.065
2.29
0.84
3.015
C18:1ω-9
7.03
5.62
7.735
16.25
7.51
20.62
C18:2ω-6
1.74
1.27
1.975
2.71
1.92
3.105
Example 1
Palm stearin with the palmitic acid content of 91.2 percent and the sn-2 palmitic acid content of 85.4 percent is selected as the starting material. The analysis revealed that the saturated fatty acids at the sn-2 position of palm stearin are deficient in medium carbon chain fatty acids and myristic acid (C14:0) relative to human milk fat.
TABLE 2 fatty acid profile of breast milk fat and palm stearin
Breast milk fat
Palm stearin
Sn-2
Sn-1,3
min
max
min
max
General assembly
sn-2
C6:0
0.01
0.11
0.01
0.18
C8:0
0.03
1.08
0.08
1.43
C10:0
0.36
1.62
0.11
3.48
C12:0
1.95
13.69
1.94
10.56
C14:0
3.29
18.55
3.88
7.21
1.4
0.2
C16:0
37.02
66.33
3.49
12.66
91.2
85.4
C18:0
1.18
3.43
2.09
12.73
3.1
2.1
C18:1ω-9
5.41
23.27
30.64
52.74
3.6
9.6
C18:2ω-6
2.59
17.4
16.79
39.81
0.7
2.1
C18:3ω-3
0.55
2.78
1.13
2.19
Analysis of breast milk fat shows that saturated fatty acid in breast milk is mainly in sn-2 position, mainly comprises C6-C18 saturated fatty acid, and also comprises unsaturated fatty acid such as oleic acid, linoleic acid, linolenic acid and the like. And in the sn-1 and 3 positions, unsaturated fatty acids are mainly used, such as oleic acid, linoleic acid, linolenic acid and the like. In nature, the content of sn-2 saturated and sn-1,3 unsaturated fatty acid triglyceride is very low, so that the synthesis of the sn-1,3 unsaturated and sn-2 saturated fatty acid triglyceride with the sn-2 saturated fatty acid consistent with breast milk fat as an additive for regulating the triglyceride structure of the infant formula milk powder has important significance.
By establishing a sn-2 fatty acid mixed model of the oil, the composition of sn-2 saturated fatty acid in the oil is adjusted to be within the fat range of breast milk.
The sn-2 fatty acid mixing model of the grease is as follows:
according to the fatty acid composition and distribution of the oil, establishing a calculation model of the sn-2 fatty acid composition of the oil:
wherein sn-2 FA% is sn-2 fatty acid composition of mixed oil, and Y1(sn-2)And Yi(sn-2)Respectively the content of each fatty acid on the sn-2 position of the palm stearin and the selected oil, and Xi is the molar ratio of the selected oil to the palm stearin;
wherein FA% is fatty acid composition of the mixed oil, sn-1,3 FA% is sn-1,3 fatty acid composition of the mixed oil, and Y1 and Yi are content of each fatty acid of the palm stearin and the selected oil respectively.
By setting Xi, the fatty acid composition and distribution in the mixed system can be calculated according to the formula, an inequality is established according to the characteristics of the sn-2 fatty acid composition of the breast milk fat, the addition range of each oil in the sn-2 fatty acid range of the breast milk fat is calculated, and finally the total fatty acid composition and the sn-1,3 fatty acid composition are calculated according to the formulas 2 and 3.
Considering that 5-30% of vegetable oil needs to be added into the final product to adjust other fatty acid compositions, the composition range of sn-2 saturated fat in breast milk fat is correspondingly improved to meet the requirement of later-stage oil mixing.
TABLE 3 Breast milk fatty acid amplification Range
When the addition amount of the exogenous oil is 20%, the palm stearin sn-2 saturated fatty acid composition is adjusted by using coconut oil as a raw material, and the ratio of the addition amounts of the palm stearin and the coconut oil is assumed to be 1: x1, establishing an inequality through a grease sn-2 fatty acid mixed model, wherein the inequality is as follows:
Sn-2C6:0:0.01≤X1*0.05/(1+X1)≤0.13
Sn-2C8:0:0.04≤X1*1.43/(1+X1)≤1.3
Sn-2C10:0:0.43≤X1*3.46/(1+X1)≤1.94
Sn-2C12:0:2.34≤X1*60.02/(1+X1)≤16.43
Sn-2C14:0:3.95≤0.2+X1*22.15/(1+X1)≤22.26
Sn-2C16:0:44.42≤(85.4+X1*5.06)/(1+X1)≤79.6
Sn-2C18:0:1.42≤(2.1+X1*0.87)//(1+X1)≤4.12
it can be calculated that when the ratio of palm stearin to coconut oil is 1: 0.15-0.35, the composition of sn-2 fatty acid of the resulting mixed product is within the range, and the results are shown below.
TABLE 4 fatty acid profile of fat blends
And (3) carrying out acidolysis on fatty acid from high-oleic-acid sunflower seed oil rich in oleic acid, wherein the acidolysis proportion of the fatty acid is predicted by an acidolysis reaction fatty acid balance model.
Due to the high palmitic acid content of the starting material, a two-step acidolysis process is considered for the preparation of a triglyceride product enriched in 1, 3-unsaturated 2-saturated fatty acid structures. In order to obtain higher product content and reduce the use amount of free fatty acid as much as possible, a fat acidolysis fatty acid balance model is adopted in the two-step acidolysis method to determine the substrate ratio in the two-step acidolysis process and predict the composition of the fatty acid in the product, and meanwhile, in order to reduce acyl transfer, the replaced palmitic acid in the acidolysis reaction is removed in a low-temperature crystallization mode between the two-step acidolysis reaction.
The acidolysis reaction fatty acid equilibrium model is as follows:
in the reaction system, the content of triglyceride is m, the content of fatty acid is h, in the reaction process, the used lipase is sn-1,3 position specific lipase, and the fatty acid accords with random distribution on sn-1,3 positions. In the whole reaction system, the fatty acid types are defined as n, different fatty acids are defined as Xi, the amount of change of sn-2 fatty acid is small by controlling acyl transfer using reaction conditions, and therefore, the change of sn-2 fatty acid can be ignored. In the system, the fatty acids participating in the reaction are mainly triglyceride sn-1,3 fatty acids and added free fatty acids. For individual fatty acids Xi, the mole percentage of Xi fatty acids at the sn-1,3 positions of the triglycerides can be expressed as Msn-1/-3Xi, and the mole percentage of free fatty acids Xi can be expressed as MXi, so that when the system reaches equilibrium, the Xi fatty acids are present at equilibrium in the reaction at a level of sn-1,3 content of the triglycerides (sn-1/3Xi) according to the random distribution principle:
due to the fact thatTherefore, the temperature of the molten metal is controlled,the model can be further simplified as:
let h/m be S, i.e. the molar ratio of free fatty acids to triglycerides is S: 1, therefore, the sn-1,3 content of triglycerides at the equilibrium of the Xi fatty acid reaction can be further reduced to:
wherein M issn-1/3XiIs the molar percentage of Xi fatty acids in the sn-1,3 position of the triglyceride; mXiIs the mole percentage of free fatty acids Xi; s is free fatMolar ratio of fatty acids to triglycerides.
According to the model, theoretical values of fatty acids reaching the composition of the sn-1 and 3 fatty acids of the breast milk fat under different substrate ratios can be calculated, and experimental conditions with higher oleic acid content or lower palmitic acid content under lower free fatty acids are selected according to the theoretical values.
Taking the mixed oil 1 as an example, the fatty acid distribution of the products with different substrate ratios used in the two-step acidolysis was calculated according to the above model as shown below.
TABLE 5 theoretical composition of sn-1,3 fatty acids in different substrates versus the acidolysis product of the next step
TABLE 6 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 1 different substrate ratios in two-step acidolysis product
TABLE 7 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 2 different substrate ratios in two-step acidolysis product
TABLE 8 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 3 different substrate ratios in two-step acidolysis product
TABLE 9 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 4 different substrate ratios in two-step acidolysis product
TABLE 10 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 5 different substrate ratios in two-step acidolysis product
From the table, it can be concluded that when the use amount of the fatty acid in the two-step acidolysis reaction is determined to be 8-14:1, the palmitic acid content of the final product is low, and the oleic acid content is high. Therefore, a substrate ratio of 6:1(mol/mol) of fatty acid to triglyceride is selected for acidolysis reaction, firstly, 1, 3-position palmitic acid is replaced by one-step acidolysis reaction, then, the palmitic acid in the free fatty acid is separated and removed by adopting a low-temperature procedure by utilizing the difference of melting points, the unsaturated degree of the free fatty acid is increased, then, two-step acidolysis reaction is carried out, and finally, the fatty acid is removed by reduced pressure distillation, so that the final product is obtained.
Wherein, the conditions of the one-step acidolysis reaction are as follows: mixing fatty acid and mixed grease according to the ratio of 6:1(mol/mol), heating to 60 ℃, keeping the temperature for 30min, leading the mixture into a packed bed reactor after the mixture is completely dissolved, wherein lipase used by the packed bed reactor is Lipozyme RM IM, the temperature of the packed bed is kept at 60 ℃, the retention time of the grease in the packed bed is 2 hours, and obtaining an acidolysis product after the reaction is finished. The packed bed reactor was first purged with nitrogen instead of air before purging the mixed fat.
The low-temperature procedure fractionation palmitic acid conditions were: heating the oil to 60 ℃ and maintaining for 45min, then reducing the temperature to 28 ℃ at the speed of 4 ℃/h, growing crystals for 5h at the rotating speed of 40 r/min, and filtering or centrifugally separating solid fat after fractionation and crystallization is finished to obtain liquid oil;
the two-step acidolysis reaction conditions are as follows: heating liquid oil to 50 ℃, keeping the temperature for 30min, introducing the heated liquid oil into a packed bed reactor, wherein lipase used by the packed bed reactor is Lipozyme RM IM, the temperature of the packed bed is kept at 50 ℃, the retention time of grease in the packed bed is 3 hours, and obtaining an acidolysis product after the reaction is finished. Finally, the possible impurities are separated by centrifugation or filtration and the free fatty acids are removed by distillation under reduced pressure.
The fatty acid composition and distribution of the two acidolysis products are shown below.
TABLE 11 fatty acid composition and distribution of the products obtained from the acidolysis reaction
Adding 20% of soybean oil, palm kernel oil and linseed oil according to the composition of breast milk fat, wherein the secondary enzymolysis product: soybean oil: palm kernel oil: the linseed oil is 1:0.15:0.04:0.01, the proportion is determined by a fat mixing model, and the fatty acid composition of the obtained product is shown as follows, so that the requirement of breast milk fat is met.
TABLE 12 fatty acid profile of the product
General assembly
sn-2
sn-1,3
C6:0
0.01
0.01
0.01
C8:0
0.21
0.20
0.22
C10:0
0.42
0.41
0.42
C12:0
3.87
7.98
1.82
C14:0
2.76
2.73
2.78
C16:0
28.53
59.24
13.17
C18:0
2.61
2.21
2.81
C18:1ω-9
46.08
14.78
61.73
C18:2ω-6
13.89
11.41
15.13
C18:3ω-3
1.51
0.95
1.79
Example 2
Palm stearin with 82.4% of palmitic acid content and 73.5% of sn-2 palmitic acid content is selected as a starting material. The analysis shows that the saturated fatty acid at the sn-2 position of the palm stearin is lack of medium carbon chain fatty acid relative to the breast milk fat.
TABLE 13 fatty acid profile of Breast milk fat and palm stearin
Breast milk fat
Palm stearin
Sn-2
Sn-1,3
min
max
min
max
General assembly
sn-2
C6:0
0.01
0.11
0.01
0.18
C8:0
0.03
1.08
0.08
1.43
C10:0
0.36
1.62
0.11
3.48
C12:0
1.95
13.69
1.94
10.56
C14:0
3.29
18.55
3.88
7.21
1
0.3
C16:0
37.02
66.33
3.49
12.66
82.4
73.5
C18:0
1.18
3.43
2.09
12.73
3.9
3.7
C18:1ω-9
5.41
23.27
30.64
52.74
10.1
18.3
C18:2ω-6
2.59
17.4
16.79
39.81
2.6
4.1
C18:3ω-3
0.55
2.78
1.13
2.19
Analysis of breast milk fat shows that the saturated fatty acid in breast milk is mainly in the sn-2 position, mainly comprises C6-C18 saturated fatty acid, and also comprises unsaturated fatty acid such as oleic acid, linoleic acid, linolenic acid and the like. And in the sn-1 and 3 positions, unsaturated fatty acids are mainly used, such as oleic acid, linoleic acid, linolenic acid and the like. In nature, the content of sn-2 saturated and sn-1,3 unsaturated triglyceride is very low, so that the sn-1,3 unsaturated and sn-2 saturated fatty acid triglyceride serving as an additive for regulating the triglyceride structure of the infant formula by synthesizing the sn-2 saturated fatty acid to be consistent with breast milk fat has important significance.
And establishing an inequality of the mixed oil sn-2 fatty acid in the range of breast milk fat by adopting an oil sn-2 fatty acid mixed model. Considering that 5-30% of vegetable oil needs to be added in the final product to adjust other fatty acid compositions, the composition range of sn-2 saturated fat in breast milk fat is enlarged by 5-30% to meet the requirement of later oil mixing.
When the addition amount of the exogenous grease is about 10%, an inequality is established through a grease sn-2 fatty acid mixing model.
TABLE 14 Breast milk fatty acid amplification Range
sn-2
10％
min
max
min
max
C6:0
0.01
0.11
0.01
0.12
C8:0
0.03
1.08
0.03
1.19
C10:0
0.36
1.62
0.40
1.78
C12:0
1.95
13.69
2.15
15.06
C14:0
3.29
18.55
3.62
20.41
C16:0
37.02
66.33
40.72
72.96
C18:0
1.18
3.43
1.30
3.77
C18:1ω-9
5.41
23.27
5.95
25.60
C18:2ω-6
2.59
17.4
2.85
19.14
C18:3ω-3
0.55
2.78
0.61
3.06
When the addition amount of the exogenous oil is 10%, the palm stearin sn-2 saturated fatty acid composition is adjusted by using the palm kernel oil as a raw material, and the ratio of the addition amounts of the palm stearin and the coconut oil is assumed to be 1: x1, establishing an inequality through a grease sn-2 fatty acid mixed model, wherein the inequality is as follows:
Sn-2C6:0:0.01≤X1*0.06/(1+X1)≤0.12
Sn-2C8:0:0.03≤X1*1.78/(1+X1)≤1.19
Sn-2C10:0:0.4≤X1*2.89/(1+X1)≤1.78
Sn-2C12:0:2.15≤X1*61.38/(1+X1)≤15.06
Sn-2C14:0:3.62≤(0.3+X1*18.98)/(1+X1)≤20.41
Sn-2C16:0:40.72≤(73.5+X1*4.69)/(1+X1)≤72.96
Sn-2C18:0:1.3≤(3.7+X1*0.84)/(1+X1)≤3.77
it can be calculated that when the ratio of palm stearin to palm kernel oil is 1:0.22-0.33, the composition of sn-2 fatty acids of the resulting blended product is within the range, and the results are shown below.
TABLE 15 fatty acid profile of fat blends
The mixed oil 2 was selected for acidolysis experiments. The theoretical composition of sn-1,3 fatty acid under different acidolysis reaction balances can be calculated through a grease acidolysis balance model.
The theoretical equilibrium value of sn-1,3 fatty acid of the obtained product under different substrate ratios is calculated by using fatty acid derived from high oleic soybean oil as an acyl donor and utilizing an acidolysis reaction fatty acid equilibrium model, and the result is shown as follows.
TABLE 16 theoretical composition of sn-1,3 fatty acids in different substrates versus the product of the next acidolysis
TABLE 17 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 1 different substrate ratios in two-step acidolysis product
TABLE 18 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 2 different substrate ratios in two-step acidolysis product
TABLE 19 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 3 different substrate ratios in two-step acidolysis product
TABLE 20 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 4 different substrate ratios in two-step acidolysis product
TABLE 21 theoretical composition of sn-1,3 fatty acids in one-step acidolysis product 5 different substrate ratios in two-step acidolysis product
From the above table it can be concluded that when the fatty acid dosage of the two-step acid is determined to be 8-12:1, the final product obtained has a lower palmitic acid content and a higher oleic acid content.
Therefore, a substrate ratio of fatty acid to triglyceride of 5:1(mol/mol) is selected for acidolysis reaction, firstly, 1, 3-position palmitic acid is replaced by one-step acidolysis reaction, then, the palmitic acid in the free fatty acid is separated and removed by adopting a low-temperature procedure by utilizing the difference of melting points, the unsaturated degree of the free fatty acid is increased, then, the second-step acidolysis reaction is carried out, and finally, the fatty acid is removed by reduced pressure distillation, so that the final product is obtained.
Wherein, the conditions of the one-step acidolysis reaction are as follows: mixing fatty acid and mixed grease according to the proportion of 5:1(mol/mol), heating to 65 ℃, keeping for 20min, leading the mixture into a packed bed reactor after the mixture is completely dissolved, wherein lipase used by the packed bed reactor is Lipzyme TL IM, the temperature of the packed bed is kept at 55 ℃, the retention time of the grease in the packed bed is 3 hours, and obtaining an acidolysis product after the reaction is finished. The packed bed reactor was first purged with nitrogen instead of air before purging the mixed fat.
The low-temperature procedure fractionation palmitic acid conditions were: heating the oil to 65 ℃ and maintaining for 20min, then reducing the temperature to 30 ℃ at the speed of 10 ℃/h, growing crystals for 3h at the rotating speed of 30 r/min, and filtering or centrifugally separating solid fat after fractionation and crystallization is finished to obtain liquid oil;
the two-step acidolysis reaction conditions are as follows: heating liquid oil to 55 ℃, keeping the temperature for 20min, introducing the heated liquid oil into a packed bed reactor, wherein lipase used by the packed bed reactor is Lipzyme TL IM, the temperature of the packed bed is kept at 45 ℃, the retention time of grease in the packed bed is 4 hours, and obtaining an acidolysis product after the reaction is finished. Finally, the lipase is separated by centrifugation or filtration and the free fatty acids are removed by distillation under reduced pressure.
The fatty acid composition and distribution of the two acidolysis products are shown below.
TABLE 22 fatty acid composition and distribution of the products obtained from the acidolysis reaction
Adding 10% of soybean oil, palm kernel oil and linseed oil according to the fat composition of breast milk, wherein the secondary enzymolysis product: soybean oil: palm kernel oil: linseed oil is 1:0.08:0.01:0.01, and the fatty acid composition of the obtained product is shown as follows, so that the requirement of breast milk fat is met.
TABLE 23 fatty acid characterization of the product
General assembly
sn-2
sn-1,3
C6:0
0.00
0.01
0.00
C8:0
0.15
0.27
0.09
C10:0
0.25
0.54
0.10
C12:0
4.66
13.03
0.47
C14:0
1.47
3.68
0.36
C16:0
25.47
49.78
13.32
C18:0
2.22
1.80
2.43
C18:1ω-9
47.58
17.82
62.46
C18:2ω-6
15.26
11.69
17.05
C18:3ω-3
2.63
1.14
3.37
Example 3
Palm stearin with 70.3% of palmitic acid content and 58.3% of sn-2 palmitic acid content is selected as a starting material.
TABLE 24 fatty acid profile of breast milk fat and palm stearin
Breast milk fat
Palm stearin
Sn-2
Sn-1,3
min
max
min
max
General assembly
sn-2
C6:0
0.01
0.11
0.01
0.18
C8:0
0.03
1.08
0.08
1.43
C10:0
0.36
1.62
0.11
3.48
C12:0
1.95
13.69
1.94
10.56
C14:0
3.29
18.55
3.88
7.21
1.4
0.8
C16:0
37.02
66.33
3.49
12.66
70.3
58.3
C18:0
1.18
3.43
2.09
12.73
5.6
4.2
C18:1ω-9
5.41
23.27
30.64
52.74
18.8
25.7
C18:2ω-6
2.59
17.4
16.79
39.81
3.9
10.2
C18:3ω-3
0.55
2.78
1.13
2.19
Analysis of breast milk fat shows that saturated fatty acid in breast milk is mainly in sn-2 position, mainly comprises C6-C18 saturated fatty acid, and also comprises unsaturated fatty acid such as oleic acid, linoleic acid, linolenic acid and the like. And in the sn-1 and 3 positions, unsaturated fatty acids are mainly used, such as oleic acid, linoleic acid, linolenic acid and the like.
And establishing an inequality of the mixed oil sn-2 fatty acid in the range of breast milk fat by adopting an oil sn-2 fatty acid mixed model. Considering that 5% of vegetable oil needs to be added in the final product to adjust other fatty acid compositions, the composition range of sn-2 saturated fat in breast milk fat is improved by 5% to meet the requirement of later-stage oil mixing.
TABLE 25 Breast milk fatty acid amplification Range
sn-2
5％
min
max
min
max
C6:0
0.01
0.11
0.01
0.12
C8:0
0.03
1.08
0.03
1.13
C10:0
0.36
1.62
0.38
1.70
C12:0
1.95
13.69
2.05
14.37
C14:0
3.29
18.55
3.45
19.48
C16:0
37.02
66.33
38.87
69.65
C18:0
1.18
3.43
1.24
3.60
C18:1ω-9
5.41
23.27
5.68
24.43
C18:2ω-6
2.59
17.4
2.72
18.27
C18:3ω-3
0.55
2.78
0.58
2.92
When the addition amount of the exogenous oil is 5%, the coconut oil is used as a raw material to adjust the composition of the palm stearin sn-2 saturated fatty acid, and the ratio of the addition amount of the coconut oil to the addition amount of the palm stearin is assumed to be 1: x1, establishing an inequality through a grease sn-2 fatty acid mixed model, wherein the inequality is as follows:
Sn-2C6:0:0.01≤X1*0.05/(1+X1)≤0.12
Sn-2C8:0:0.03≤X1*1.43/(1+X1)≤1.13
Sn-2C10:0:0.38≤X1*3.46/(1+X1)≤1.7
Sn-2C12:0:2.05≤X1*60.02/(1+X1)≤14.37
Sn-2C14:0:3.45≤(0.8+X1*22.15)/(1+X1)≤19.48
Sn-2C16:0:38.87≤(58.3+X1*5.06)/(1+X1)≤69.65
Sn-2C18:0:1.24≤(4.2+X1*0.87)/(1+X1)≤3.6
finally, when the scope of the breast milk fat sn-2 saturated fatty acid is satisfied, the ratio of the palm stearin to the coconut oil is 1: 0.13-0.31. The fatty acid composition and the distribution range of the mixed fat at the two critical points are shown below.
TABLE 26 fatty acid profile of fat blends
Mixture 1
Mixture 2
1：0.13
1：0.31
General assembly
Sn-2
Sn-1,3
General assembly
Sn-2
Sn-1,3
C6:0
0.01
0.01
0.01
0.01
0.01
0.01
C8:0
0.16
0.16
0.16
0.34
0.34
0.34
C10:0
0.40
0.40
0.40
0.82
0.82
0.82
C12:0
6.90
6.90
6.90
14.20
14.20
14.20
C14:0
3.79
3.26
4.05
6.31
5.85
6.54
C16:0
62.79
52.18
68.10
54.86
45.70
59.44
C18:0
5.06
3.82
5.68
4.48
3.41
5.02
C18:1ω-9
17.28
23.39
14.23
15.68
20.95
13.05
C18:2ω-6
3.60
9.17
0.81
3.28
8.09
0.87
C18:3ω-3
0.00
0.00
0.00
0.00
0.00
0.00
The mixture 1 is selected for acidolysis reaction, fatty acid of the high-oleic-acid peanut oil is used as an acyl donor, and the fatty acid acidolysis reaction equilibrium model prediction shows that when the fatty acid dosage in the two-step acidolysis reaction is determined to be 6-10:1, the palmitic acid content of the final product is lower, and the oleic acid content is higher.
Therefore, an acid hydrolysis experiment was conducted with the substrate ratio of the acid hydrolysis reaction determined to be 4:1, and the results obtained are shown below.
Wherein, the conditions of the one-step acidolysis reaction are as follows: mixing fatty acid and mixed grease according to a ratio of 4:1(mol/mol), heating to 55 ℃, keeping for 45min, leading the mixture into a packed bed reactor after the mixture is completely dissolved, wherein lipase used by the packed bed reactor is NS40086, the temperature of the packed bed is kept at 60 ℃, the retention time of the grease in the packed bed is 1 hour, and obtaining an acidolysis product after the reaction is finished. The packed bed reactor was first purged with nitrogen instead of air before purging the mixed fat.
The low-temperature procedure fractionation palmitic acid conditions were: heating oil to 70 deg.C and maintaining for 20min, cooling to 35 deg.C at 8 deg.C/h, growing crystal for 6h at a rotation speed of 20 r/min, and filtering or centrifuging to separate solid fat to obtain liquid oil;
the two-step acidolysis reaction conditions are as follows: heating liquid oil to 60 ℃, keeping the temperature for 15min, introducing the heated liquid oil into a packed bed reactor, wherein the lipase used by the packed bed reactor is NS40086, the temperature of the packed bed is kept at 60 ℃, the retention time of the oil in the packed bed is 1 hour, and obtaining an acidolysis product after the reaction is finished. Finally, the possible impurities are separated by centrifugation or filtration and the free fatty acids are removed by distillation under reduced pressure.
The fatty acid composition and distribution of the two acidolysis products are shown below.
TABLE 27 fatty acid composition and distribution of the products obtained from the acidolysis reaction
One-step acidolysis
Two-step acidolysis
General assembly
Sn-2
Sn-1,3
General assembly
Sn-2
Sn-1,3
C6:0
0.01
0.01
0.00
0.00
0.01
0.00
C8:0
0.08
0.13
0.05
0.05
0.11
0.01
C10:0
0.20
0.32
0.13
0.14
0.35
0.03
C12:0
3.57
6.10
2.30
2.31
5.77
0.58
C14:0
1.94
3.12
1.35
1.22
2.98
0.34
C16:0
36.96
51.34
26.77
25.81
49.41
14.02
C18:0
3.72
3.23
3.96
3.26
3.14
3.32
C18:1ω-9
45.54
25.26
58.68
58.11
27.13
73.59
C18:2ω-6
6.55
9.52
6.07
8.01
10.43
6.79
C18:3ω-3
0.73
0.58
0.80
0.93
0.58
1.10
Adding 5% of soybean oil, palm kernel oil and linseed oil according to the fat composition of breast milk, wherein the secondary enzymolysis product: soybean oil: coconut oil: linseed oil is 1:0.03:0.01:0.01, and the fatty acid composition of the obtained product is shown as follows, so that the requirement of breast milk fat is met.
TABLE 28 fatty acid characterization of the product
Fatty acids
General assembly
sn-2
sn-1,3
C6:0
0.01
0.01
0.00
C8:0
0.07
0.12
0.04
C10:0
0.16
0.36
0.06
C12:0
2.65
6.08
0.93
C14:0
1.32
3.02
0.47
C16:0
24.98
47.25
13.84
C18:0
3.29
3.08
3.40
C18:1ω-9
56.35
26.91
71.07
C18:2ω-6
9.40
12.08
8.06
C18:3ω-3
1.60
1.00
1.89
Example 4
Taking the mixed oil 2 in example 1 as a starting material, taking the soybean oil and the rapeseed oil as a mixed oil fatty acid acyl donor in a ratio of 1:1, and carrying out acidolysis on the mixed oil 2, and calculating by using an acidolysis reaction fatty acid balance model, when the dosage of the fatty acid in the two-step acidolysis reaction is determined to be 8-14:1, the obtained final product has low palmitic acid content and high oleic acid content. Therefore, a substrate ratio of fatty acid to triglyceride of 7:1(mol/mol) is selected for acidolysis reaction, firstly, 1, 3-position palmitic acid is replaced by one-step acidolysis reaction, then, the palmitic acid in the free fatty acid is separated and removed by adopting a low-temperature procedure by utilizing the difference of melting points, the unsaturated degree of the free fatty acid is increased, then, two-step acidolysis reaction is carried out, and finally, the fatty acid is removed by reduced pressure distillation, so that the final product is obtained.
Wherein, the conditions of the one-step acidolysis reaction are as follows: mixing fatty acid and mixed grease according to a ratio of 7:1(mol/mol), heating to 60 ℃, keeping for 30min, introducing the mixture into a packed bed reactor after the mixture is completely dissolved, wherein Lipase used by the packed bed reactor is Lipase DF, the temperature of the packed bed is kept at 50 ℃, the retention time of the grease in the packed bed is 4 hours, and obtaining an acidolysis product after the reaction is finished. The packed bed reactor was first purged with nitrogen instead of air before purging the mixed fat.
The low-temperature procedure fractionation palmitic acid conditions were: heating oil to 55 deg.C and maintaining for 40min, cooling to 25 deg.C at a speed of 15 deg.C/h, growing crystal for 10h, and filtering or centrifuging to separate solid fat to obtain liquid oil.
The two-step acidolysis reaction conditions are as follows: heating liquid oil to 55 ℃, keeping the temperature for 20min, introducing the heated liquid oil into a packed bed reactor, wherein Lipase DF is used as Lipase, the temperature of the packed bed is kept at 50 ℃, the retention time of the grease in the packed bed is 2 hours, and obtaining acidolysis products after the reaction is finished. Finally, the possible impurities are separated by centrifugation or filtration and the free fatty acids are removed by distillation under reduced pressure.
The fatty acid composition and distribution of the two acidolysis products are shown below.
TABLE 29 fatty acid composition and distribution of the products obtained from the acidolysis reaction
One-step acidolysis
Two-step acidolysis
Fatty acids
General assembly
Sn-2
Sn-1,3
General assembly
Sn-2
Sn-1,3
C6:0
0.01
0.02
0.01
0.00
0.01
0.00
C8:0
0.23
0.28
0.21
0.10
0.17
0.06
C10:0
0.34
0.74
0.14
0.21
0.55
0.04
C12:0
4.97
13.21
0.84
4.26
12.31
0.24
C14:0
2.17
4.13
1.19
1.27
3.13
0.34
C16:0
42.98
61.33
33.81
30.73
59.26
16.46
C18:0
2.71
1.52
3.30
2.58
1.32
3.21
C18:1ω-9
25.53
13.34
31.62
32.09
15.25
40.51
C18:2ω-6
16.99
4.85
23.06
24.31
6.67
33.13
C18:3ω-3
4.05
0.52
5.82
4.44
1.32
6.01
Adding 20% of soybean oil, rapeseed oil and coconut oil according to the breast milk fat composition, wherein the secondary enzymolysis product: soybean oil: the coconut oil is 1:0.1:0.02:0.08, and the fatty acid composition of the obtained product is shown as follows, so that the requirement of breast milk fat is met.
TABLE 30 fatty acid characterization of the product
Therefore, according to the invention, based on the range of 5-30% of saturated fatty acid higher than that of the sn-2 of breast milk fat, the composition of the sn-2 saturated fatty acid of the fat is adjusted through a fat mixing model, and meanwhile, a 1, 3-unsaturated-2-saturated fatty acid triglyceride product is obtained by a process technology of coupling two-step acidolysis with low-temperature program fractionation, so that the sn-1,3 unsaturated fatty acid content of the product is higher, and meanwhile, when 5-30% of fat is added externally to the obtained product, the composition of the sn-2 saturated fatty acid is still in the range of breast milk fat.
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.
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