阅读说明：本技术 一种酶法制备富含亚麻酸甘油二酯的方法 (Method for preparing diglyceride rich in linolenic acid by enzyme method ) 是由 王小三 陈烨 王熠璠 赵昕辰 于 2021-09-28 设计创作，主要内容包括：本发明公开了一种酶法制备富含亚麻酸甘油二酯的方法,属于食品加工技术领域。本发明利用酶法甘油解法制备富含亚麻酸甘油二酯,采用蒸馏或吸附的方法降低富含亚麻酸原料中的过氧化值,以实现在酶促反应过程中最大程度保留脂肪酶活力的目的,从而提高甘油解反应过程中脂肪酶的重复使用次数,降低酶法制备甘油二酯的成本。本发明提供了一种高效率、低成本的酶法合成甘油二酯油脂的方法,避免了在酶促反应过程中脂肪酶容易失活的问题,本发明所采用的方法在油脂加工中具有极大的应用前景。(The invention discloses a method for preparing diglyceride rich in linolenic acid by an enzyme method, belonging to the technical field of food processing. The invention utilizes an enzymatic glycerolysis method to prepare diglyceride rich in linolenic acid, and adopts a distillation or adsorption method to reduce the peroxide value in the raw material rich in linolenic acid so as to achieve the aim of keeping the lipase activity to the maximum extent in the enzymatic reaction process, thereby improving the repeated use times of the lipase in the glycerolysis reaction process and reducing the cost for preparing the diglyceride by the enzymatic method. The invention provides a method for synthesizing diglyceride grease by an enzyme method with high efficiency and low cost, which avoids the problem that lipase is easy to inactivate in the enzymatic reaction process, and the method has great application prospect in grease processing.)

1. A method for preparing diglyceride rich in linolenic acid by an enzyme method, which is characterized by comprising the following steps:

s1, raw material treatment: carrying out peroxide value reduction treatment on the grease rich in linolenic acid, wherein the peroxide value is required to be reduced to below 4 mmol/kg;

s2, synthesis of linolenic acid-rich diglyceride: mixing the linolenic acid-rich grease processed by the S1 with glycerol, adding or not adding an organic solvent, reacting under the catalysis of lipase, and removing the lipase and the glycerol after reacting for a certain time to obtain the linolenic acid-rich diglyceride.

2. The method as claimed in claim 1, wherein the linolenic acid-rich fat is a natural fat with a linolenic acid content of more than 30%.

3. The method as claimed in claim 1, wherein in the step of S1, the method for reducing the peroxide value of the linolenic acid-rich fat comprises either or both of distillation and adsorption; wherein the distillation method comprises any one or two of deodorization and molecular distillation.

4. A process according to claim 3, characterized in that the temperature of deodorization is 120-200 ℃, the time is 30-120 min, and the operating pressure is not higher than 4 mbar; the evaporation surface temperature of the molecular distillation is 120-200 ℃.

5. The method of claim 3, wherein the adsorbent for the adsorption method comprises one or more of silica gel, activated clay, activated carbon, silica and attapulgite.

6. A method according to any one of claims 1 to 5, wherein the molar ratio of glycerol to linolenic acid-rich oil is (0.5 to 4): 1.

7. the method according to any one of claims 1 to 5, wherein the lipase used in the S2 step includes any one or more of lipases derived from Candida antarctica (Candida antarctica), Thermomyces lanuginosus (Thermomyces lanuginosus), Rhizopus oryzae (Rhizopus oryzae), and Rhizomucor miehei (Rhizomucor miehei).

8. The method according to any one of claims 1 to 7, wherein the organic solvent used in step S2 comprises one or more of tert-butanol, isopropanol and tert-amyl alcohol.

9. The method according to any one of claims 1 to 8, wherein the reaction temperature for synthesizing the diglyceride rich in linolenic acid in the step S2 is 40 ℃ to 70 ℃, and the reaction time is 3h to 15 h.

10. Use of the process of any one of claims 1 to 9 in the production of diglyceride oil.

Technical Field

The invention belongs to the technical field of food processing, relates to a preparation method of structured fat, and particularly relates to a method for preparing diglyceride rich in linolenic acid by an enzyme method.

Background

The grease is generally synthesized by dehydration esterification of glycerin and fatty acid. Most oils and fats have the highest Triglyceride (TAG) content, which is about 95% or more of the total. Other components include Monoglyceride (MAG), Diglyceride (DAG), free fatty acid, phospholipid, etc. Diglycerides, especially 1, 3-diglyceride (1,3-DAG), which are different in metabolic pathway from triglycerides, have the effects of inhibiting the accumulation of fat in the body and helping the body control weight. At present, the obesity problem of the modern society is increasingly serious, and the research of diglyceride as an ideal substitute of triglyceride in edible oil is widely concerned and has a wide market.

DAG can improve the postprandial and fasting blood lipid level, and experiments on different populations prove the effect. For example, in the experiment of diabetic patients, after DAG is used for replacing TAG, the blood lipid level of diabetes or fasting and postprandial blood lipid is obviously reduced, and the method also has better effect on controlling the blood lipid level of the diabetic patients with hyperlipidemia. A great deal of research has proved the effects of DAG in reducing cholesterol level and blood fat, so DAG has wide application prospect in the industries of medicine, food and the like.

Currently, enzymatic methods for preparing diglycerides include a direct esterification method of glycerin and free fatty acids, a partial hydrolysis method of natural fats and oils, and a glycerolysis method. In the processes of preparing diglyceride by the first two methods, the enzymolysis crude product contains a large amount of free fatty acid, the yield of the current product is not high, and the crude product contains a large amount of free fatty acid, so that the difficulty is increased for the subsequent refining process. The method for preparing diglyceride by the enzymatic glycerolysis method has the characteristics of high yield, no free fatty acid generated in the enzymatic hydrolysis process, simple and convenient subsequent refining process and the like, but the main obstacles for the enzymatic glycerolysis in the industrial application of preparing diglyceride oil are the problems of high lipase price, limited repeated utilization times and the like.

Disclosure of Invention

[ problem ] to

The enzyme method has the advantages of less enzyme recycling times in the industrial application of preparing the diglyceride oil, high free fatty acid content in the crude product and high refining process difficulty.

[ solution ]

The method greatly increases the repeated use times of the lipase, reduces the cost of industrial production and has potential application value.

Specifically, the invention provides the following technical scheme: a method for the enzymatic preparation of a linolenic acid-rich diglyceride, comprising the steps of:

s1, raw material treatment: carrying out peroxide value reduction treatment on the grease rich in linolenic acid, wherein the peroxide value is required to be reduced to below 4 mmol/kg;

s2, synthesis of linolenic acid-rich diglyceride: mixing the linolenic acid-rich grease processed by the S1 with glycerol, adding or not adding an organic solvent, reacting under the catalysis of lipase, and removing the lipase and the glycerol after reacting for a certain time to obtain the linolenic acid-rich diglyceride.

Preferably, in the step S1, the linolenic acid-rich oil is a natural oil with a linolenic acid content of more than 30%, preferably linseed oil.

Preferably, in the step S1, the method for reducing the peroxide value of the linolenic acid-rich fat comprises either or both of a distillation method and an adsorption method.

Preferably, the distillation method comprises either or both of deodorization, molecular distillation.

Preferably, the temperature of deodorization is 120-200 ℃, the time is 30-120 min, and the operating pressure is not higher than 4 mbar.

Preferably, the temperature of an evaporation surface of the molecular distillation is 120-200 ℃, and the operation pressure is not higher than 4 mbar.

Preferably, the reaction time of the adsorption method is 25min or less.

Preferably, the adsorbent of the adsorption method comprises one or more of silica gel, activated clay, activated carbon, silicon dioxide and attapulgite, and preferably silica gel and activated carbon.

Preferably, the molar ratio of the reaction substrate glycerol to the linolenic acid-rich grease is (0.5-4): 1.

preferably, the lipase used in step S2 includes, but is not limited to, any one or more of lipases derived from Candida antarctica (Candida antarctica), Thermomyces lanuginosus (Thermomyces lanuginosus), Rhizopus oryzae (Rhizopus oryzae), Rhizomucor miehei (Rhizomucor miehei).

Preferably, the Lipase comprises Lipase DF IM and/or Lipase "Amano" DF derived from Rhizopus oryzae (Rhizopus oryzae); novozym 435, Lipozyme435 and/or Lipase CL "Amano" IM from Candida antarctica (Candida antarctica); lipozyme TL IM and/or Lipozyme TL 100L derived from Thermomyces lanuginosus; any one or more of lipases derived from Rhizomucor miehei (Rhizomucor miehei) Lipozyme RM IM and/or Lipozyme RM;

preferably, the preparation method of the diglyceride rich in linolenic acid is a batch or continuous preparation process.

Preferably, the addition amount of the lipase is 3-12% of the total mass of the reaction substrate.

Preferably, in the step of S2, the organic solvent used includes one or more of tert-butyl alcohol, isopropanol or tert-amyl alcohol.

Preferably, in step S2, the reaction temperature for synthesizing the diglyceride rich in linolenic acid is 40-70 ℃, and the reaction time is 3-15 h.

Preferably, in step S2, the pressure in the reaction system is not more than 90 mbar.

The invention also provides application of the method in the field of preparation of diglyceride grease.

The invention has the beneficial effects that:

the oil rich in linolenic acid is easy to oxidize, and the invention reduces the peroxide number of the raw material required by the enzymatic synthesis of the diglyceride rich in linolenic acid, thereby effectively increasing the recycling times of the enzyme, reducing the production cost and overcoming the problem of high cost of the lipase in the industrial production process of the diglyceride.

In addition, the product in the process of preparing the diglyceride oil by enzymatic glycerolysis has extremely low content of free fatty acid, which is beneficial to the subsequent deacidification process.

Detailed Description

The present invention is further described below with reference to examples, but the embodiments of the present invention are not limited thereto.

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

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.

1. Diglyceride analysis method: methods and analysis conditions for HPLC analysis of diglycerides refer to the zhang yu doctor paper { zhang yu, preparation and purification of DHA and 2-DHA-monoglyceride and comparative studies on the regulation of lipid metabolism in HepG2 cells [ D ]. doctor academic thesis, university of south of the river, 2019.

2. Peroxide value analysis method: the peroxide value is analyzed by referring to a method of GB5009.227-2016 determination of peroxide value in food safety national standard food.

Example 1: (reaction temperature optimization)

(1) Treating the raw materials by reducing peroxide number: deodorizing linseed oil with peroxide value of 6.4mmol/kg at 180 deg.C under 2mbar for 80 min; the peroxide value of the treated raw material is reduced to 2.6 mmol/kg.

(2) Synthesis of linolenic acid-rich diglyceride: adding glycerol (the molar ratio of the glycerol to the linseed oil is 1:2) into the linseed oil subjected to peroxide reduction treatment, then adding lipase Lipozyme435 derived from Candida antarctica (Candida antarctica), wherein the enzyme addition amount is 10% (w/w, relative to the total mass of reactants), mixing the glycerol and the lipase with each other in a 50mL reactor, quickly heating to a certain temperature, and reacting for 8 hours, wherein the pressure of a reaction system is controlled to be below 80 mbar. And after the reaction is finished, recovering lipase and removing glycerol to obtain diglyceride rich in linolenic acid, and finally detecting the content of the diglyceride in the crude product by using HPLC.

The influence of the reaction temperature in the step (2) on the content of diglyceride in the product synthesized by glycerol hydrolysis is researched, and the result is shown in table 1, so that the increase of the enzyme catalysis temperature is beneficial to the increase of the content of diglyceride in the crude product in a certain temperature range, and when the enzyme catalysis temperature is increased to be higher than 50 ℃, the influence of the continuous increase of the temperature on the content of diglyceride in the product is small.

TABLE 1 Effect of reaction temperature in step (2) on diglyceride content in crude product

Example 2: (reaction time optimization)

(1) Treating the raw materials by reducing peroxide number: deodorizing linseed oil with peroxide value of 6.4mmol/kg at 180 deg.C under 2mbar for 80 min; the peroxide value of the treated raw material is reduced to 2.6 mmol/kg.

(2) Synthesis of linolenic acid-rich diglyceride: adding glycerol (the molar ratio of the glycerol to the linseed oil is 1:2) into the linseed oil subjected to peroxide reduction treatment, then adding lipase Lipozyme435 derived from Candida antarctica (Candida antarctica) with the enzyme addition amount of 10% (w/w, relative to the total mass of reactants), mixing the glycerol and the lipase with each other in a 50mL reactor, quickly raising the temperature to 50 ℃, and reacting for a period of time, wherein the pressure of a reaction system is controlled to be below 80 mbar. And after the reaction is finished, recovering lipase and removing glycerol to obtain diglyceride rich in linolenic acid, and finally detecting the content of the diglyceride in the crude product by using HPLC.

The influence of the reaction temperature in the step (2) on the content of diglyceride in the product synthesized by glycerol hydrolysis is researched, and the result is shown in table 2, so that the increase of the enzyme catalysis time is beneficial to the increase of the content of diglyceride in the crude product in a certain temperature range, and when the enzymatic reaction time exceeds 10 hours, the continuous extension time leads to the gradual decrease of the content of diglyceride in the crude product.

TABLE 2 Effect of reaction time in step (2) on diglyceride content in crude product

Example 3: (reaction System optimization)

(1) Treating the raw materials by reducing peroxide number: deodorizing linseed oil with peroxide value of 6.4mmol/kg at 180 deg.C under 2mbar for 80 min; the peroxide value of the treated raw material is reduced to 2.6 mmol/kg.

(2) Synthesis of linolenic acid-rich diglyceride: adding glycerol (the molar ratio of the glycerol to the linseed oil is 1:2) into the linseed oil subjected to peroxide reduction treatment, then adding lipase Lipozyme435 derived from Candida antarctica (Candida antarctica) with the enzyme adding amount of 10% (w/w, relative to the total mass of reactants), mixing the glycerol and the lipase with the lipase in a 50mL reactor, adding an organic solvent which is 2 times of the total mass of a substrate into the reactor or not adding the organic solvent, then quickly raising the temperature to 50 ℃, reacting for 8 hours, and controlling the operating pressure in a solvent-free reaction system to be below 80 mbar. After the reaction is finished, the lipase is recovered and the glycerol is removed to obtain the diglyceride rich in linolenic acid oil, and finally the content of the diglyceride in the crude product is detected by using HPLC, and the result is shown in Table 3.

TABLE 3 Effect of the reaction System of step (2) on the diglyceride content of the crude product

Example 4: (optimization of Lipase)

(1) Treating the raw materials by reducing peroxide number: deodorizing linseed oil with peroxide value of 6.4mmol/kg at 180 deg.C under 2mbar for 80 min; the peroxide value of the treated raw material is reduced to 2.6 mmol/kg.

(2) And (3) synthesizing linseed oil diglyceride: adding glycerol (the molar ratio of the glycerol to the linseed oil is 1:2) into the linseed oil subjected to peroxide reduction treatment, then adding lipase derived from Candida antarctica (Candida antarctica) or lipase derived from Thermomyces lanuginosus and Rhizopus oryzae (Rhizopus oryzae) in an amount of 10% (w/w relative to the total mass of reactants), mixing the lipase and the lipase together in a 50mL reactor, then quickly heating to 50 ℃ for reaction for 10 hours, and controlling the pressure of the reaction system to be below 80 mbar. After the reaction is finished, the lipase is recovered and the glycerol is removed to obtain the diglyceride rich in linolenic acid oil, and finally the content of the diglyceride in the crude product is detected by using HPLC, and the result is shown in Table 4.

TABLE 4 influence of the kind of lipase in the reaction of step (2) on the diglyceride content of the crude product

Example 5: (optimization of substrate molar ratio)

(1) Treating the raw materials by reducing peroxide number: deodorizing linseed oil with peroxide value of 6.4mmol/kg at 180 deg.C under 2mbar for 80 min; the peroxide value of the treated raw material is reduced to 2.6 mmol/kg.

(2) Synthesis of linolenic acid-rich diglyceride: glycerol was added to flaxseed oil which had been subjected to peroxide number reduction treatment, and Lipozyme435 lipase derived from Candida antarctica (Candida antarctica) was added in an amount of 10% (w/w, based on the total mass of the reactants) and mixed together in a 50mL reactor, followed by rapid heating to 50 ℃ for 8 hours with the pressure of the reaction system controlled to 80mbar or less. After the reaction is finished, the lipase is recovered and the glycerol is removed to obtain the diglyceride rich in linolenic acid, and finally the content of the diglyceride in the crude product is detected by using HPLC, and the result is shown in Table 5.

TABLE 5 Effect of the molar ratio of Glycerol and linseed oil in step (2) on the diglyceride content of the crude product

Example 6: (different peroxide number reduction treatment methods)

(1) Treating the raw materials by reducing peroxide number: the peroxide value of 7.7mmol/kg linseed oil is reduced, and the conditions for reducing the peroxide value refer to Table 3 (all in the examples are reduced to below 4 mmol/kg).

(2) Synthesis of linolenic acid-rich diglyceride: adding glycerol (the molar ratio of the glycerol to the linseed oil is 1:1) into the linseed oil subjected to peroxide reduction treatment, then adding Lipozyme435 lipase derived from Candida antarctica (Candida antarctica) with the enzyme adding amount of 10% (w/w, relative to the total mass of reactants), mixing the two materials together in a 50mL reactor, and then quickly raising the temperature to 50 ℃ for reaction for 8 hours, wherein the pressure of the reaction system is controlled to be below 90 mbar. After the reaction was completed, the lipase was recovered and the glycerol was removed to obtain a diglyceride rich in linolenic acid, and finally the content of diglyceride in the crude product was measured by HPLC, with the results shown in table 6.

And (3) adding the lipase recovered in the step (2) into the next reaction for synthesizing the diglyceride by the enzyme method, wherein the rest conditions are consistent with those of the first reaction, and after 3 times of repeated use, detecting the content of the diglyceride in the crude product by adopting HPLC.

The influence of the raw materials on the maintenance condition of the activity of the used lipase after being treated by different peroxide value reducing methods, namely molecular distillation, deodorization and adsorption, is researched, the conditions under each method are investigated, the content of diglyceride in a crude product obtained after the lipase is repeatedly used for 3 times in an enzymatic reaction under the different peroxide value reducing methods is respectively measured, and the result is shown in table 6. The comparative example used the same starting material but without any treatment or after treatment for peroxide number reduction under optimum conditions, the diglyceride content of the crude product was enzymatically repeated 3 times.

TABLE 6 content of diglyceride in enzymatic crude product after 3 times of repeated use of enzyme

As can be seen from Table 6, the recycling rate of the enzyme can be effectively improved by using the distillation and adsorption methods to treat the raw materials, and the enzyme activity is still retained to a certain extent after 3 times of use. In the process of reducing the peroxide value of the raw material by using a distillation method, proper temperature and vacuum degree are adopted, and the over-high and over-low temperature of the distillation (molecular distillation or deodorization) are not beneficial to reducing the peroxide value of the raw material and do not utilize the increase of the content of the diglyceride in the crude product. In general, the distillation method can reduce the peroxide value of the raw material to be less than 4mmol/kg, the adsorption method is more efficient in reducing the peroxide value, and the peroxide value in the raw material can be reduced to be less than 1mmol/kg, so that the raw material treated by the adsorption method for reducing the peroxide value can obtain higher content of diglyceride in a crude product under the catalysis of lipase. In addition, the diglyceride grease obtained by the method has low acid value and meets the regulation of national standard for edible vegetable oil on the acid value, so that the subsequent deacidification process can be omitted or simplified.

When other lipases of the invention are used, the method of the invention can also effectively maintain the activity of the enzyme, increase the recycling times of the enzyme, and thus realize the improvement of the utilization rate of the enzyme.

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.