Grease composition of medium and long carbon chain triglyceride as well as preparation method and application of grease composition

Abstract

The invention belongs to the technical field of grease, and particularly relates to a grease composition of medium and long carbon chain triglyceride as well as a preparation method and application of the grease composition. According to the method, firstly, medium-long carbon chain triglyceride in milk fat is efficiently enriched through a two-step crystallization method, then separated high-melting-point milk fat serves as an acyl acceptor, free fatty acid serves as an acyl donor, an enzymatic acidolysis reaction is carried out, and the medium-long carbon chain triglyceride rich in Sn-2 palmitic acid is synthesized. The grease composition of the milk-derived medium-long carbon chain triglyceride prepared by the invention is a pure natural grease component separated from cow milk fat, and the content of unsaturated fatty acid is high; medium-chain fatty acid and unsaturated fatty acid are mainly distributed at the Sn-1 site and the 3 site of the prepared grease composition of medium-long carbon chain triglyceride rich in Sn-2 palmitic acid, long-chain saturated fatty acid palmitic acid is mainly distributed at the Sn-2 site, and the triglyceride configuration of the grease composition is mainly an MLL type containing one medium-chain fatty acid.

Description

Technical Field

[0001] This application belongs to the technical field of oils and fats, and particularly relates to an oil and fat composition of medium and long-chain triglycerides, a preparation method thereof, and an application thereof. Background Art

[0002] Medium and long-chain triglycerides (MLCT) contain both medium-chain fatty acids (C8-C12) and long-chain fatty acids (C14 and above) in their molecules. After hydrolysis in the body, medium-chain fatty acids can be rapidly absorbed by the small intestine, directly enter the portal vein and be transported to the liver for oxidative metabolism, generating acetyl-CoA to enter the tricarboxylic acid cycle for oxidative decomposition to supply energy. Compared with long-chain triglycerides, it has the characteristics of high digestion and absorption rate and fast energy supply speed. In addition, medium and long-chain triglycerides also have physiological functions such as regulating lipid metabolism, improving liver function, reducing blood lipid and cholesterol levels, and inhibiting body fat accumulation.

[0003] Natural medium and long-chain triglycerides mainly exist in mammalian milk fat, coconut oil, and palm kernel oil. Existing separation methods are difficult to efficiently separate them. Currently, medium and long-chain triglycerides all use medium-chain triglycerides or coconut oil or palm kernel oil as the source of medium-chain fatty acids, and are prepared by enzymatic transesterification with edible vegetable oils. The fatty acids at the Sn-2 position are mainly medium-chain fatty acids and unsaturated fatty acids, and there is almost no palmitic acid or its content is extremely low at the Sn-2 position. However, there are a large number of medium and long-chain triglycerides with Sn-2 palmitic acid in breast milk fat. Research shows that this special fatty acid distribution has unique physiological functions. Since the melting point of palmitic acid is relatively high, when it exists in the free state in the small intestine, it is easy to combine with dietary calcium ions to form insoluble calcium soaps, causing the loss of fat and calcium, and easily leading to infant constipation. When palmitic acid is distributed at the Sn-2 position, it can be directly absorbed and utilized by the small intestine in the form of monoglyceride. In addition, Sn-2 palmitic acid-containing triglycerides are also considered to have the effect of improving cognition. This specific fatty acid distribution pattern is very important for the growth and development of infants. Therefore, existing plant-derived medium and long-chain triglycerides are not suitable for the nutritional needs of infants.

[0004] Fat provides about 50% of the energy for the growth and development of infants. Therefore, its fatty acid composition and triglyceride structure are crucial for the growth and development of infants. Currently, the medium-chain fatty acids in commercially available infant formula milk mainly come from coconut oil or palm kernel oil, and the medium-chain fatty acids mainly exist in the form of MMM and MML type triglycerides. The energy supply of triglycerides of this configuration is extremely fast, which does not meet the physiological needs of infants. In breast milk, medium-chain fatty acids mainly exist in the form of MLL type triglycerides, and the hydrolysis rate is gentle, which is more in line with the physiological and growth needs of infants. Therefore, developing a medium and long-chain triglyceride product that is more similar to breast milk in terms of fatty acid composition and structure, and making it more in line with the digestive characteristics of the infant gastrointestinal tract, is of great significance for improving the nutritional needs of infants. Summary of the Invention

[0005] The object of the present invention is to solve the deficiencies of the prior art and provide an oil and fat composition of medium and long-chain triglycerides, a preparation method and an application thereof. Specifically, the following technical solutions are adopted: In the first aspect, the present invention provides an oil and fat composition of medium and long-chain triglycerides, and the oil and fat composition comprises an oil and fat composition of milk source medium and long-chain triglycerides and / or an oil and fat composition of medium and long-chain triglycerides containing Sn-2 palmitic acid; The oil and fat composition of milk source medium and long-chain triglycerides is a pure natural oil and fat composition of medium and long-chain triglycerides. Among them, the content ratio of medium-chain fatty acids to long-chain fatty acids is 0.9-1:9-9.1, and the content of unsaturated fatty acids exceeds 40%; in terms of triglyceride composition, triglycerides containing one medium-chain fatty acid account for 30%-40% of the total triglyceride content, triglycerides containing two medium-chain fatty acids account for 5%-10% of the total triglyceride content, and triglycerides containing three medium-chain fatty acids account for 10%-15% of the total triglyceride content; In the oil and fat composition of medium and long-chain triglycerides rich in Sn-2 palmitic acid, the content ratio of medium-chain fatty acids to long-chain fatty acids is 1-1.2:8.8-9, the ratio of n-6 / n-3 polyunsaturated fatty acids is 4-6, the content of saturated fatty acids at the Sn-2 position is more than 75%, and the content of palmitic acid exceeds 45%; in terms of triglyceride composition, triglycerides containing one medium-chain fatty acid account for 40%-60% of the total triglyceride content, triglycerides containing two medium-chain fatty acids account for 5%-10% of the total triglyceride content, and triglycerides containing three medium-chain fatty acids account for less than 3% of the total triglyceride content.

[0006] A method for efficiently enriching and separating medium and long-chain triglycerides from milk fat is provided. The medium and long-chain triglycerides are characterized by being pure natural and having a high content of unsaturated fatty acids, being easy to digest and absorb, and can be used as a food additive. Preferably, it can be directly used in various nutritional foods, special medical foods, infant formula milk powder, senior foods, etc.

[0007] A method for preparing MLL-type medium and long-chain triglycerides rich in Sn-2 palmitic acid by enzymatic modification of high-melting-point milk fat is also provided. The digestion and absorption of the medium and long-chain triglycerides conform to the gastrointestinal characteristics of infants and can be used as a food additive. Preferably, it is used as a breast milk substitute fat in infant formula milk powder.

[0008] The above-mentioned medium and long-chain triglycerides refer to those containing both medium-chain fatty acids and long-chain fatty acids on the same glycerol molecular backbone. Among them, medium-chain fatty acids refer to fatty acids with 8-12 carbon atoms, and long-chain fatty acids are fatty acids with 14 or more carbon atoms.

[0009] As a further preferred embodiment, both the medium-chain fatty acids and long-chain fatty acids in the oil and fat composition of medium-chain and long-chain triglycerides in the milk source are derived from milk fat; The medium-chain fatty acids and long-chain fatty acids in the oil and fat composition of medium-chain and long-chain triglycerides rich in Sn-2 palmitic acid are derived from vegetable oil, milk fat, and lauric acid.

[0010] Second, the present invention provides a method for preparing an oil and fat composition of medium-chain and long-chain triglycerides, which is characterized by including the following steps: S1: After heating and melting cow milk fat, it is mixed evenly with a solvent, and then gradually cooled for crystallization. Through specific enrichment, an oil and fat composition of medium-chain and long-chain triglycerides in the milk source is prepared, and at the same time, the high-melting-point component of milk fat is separated; S2: The high-melting-point component of milk fat separated in step S1 is mixed with an acyl donor, and an acidolysis reaction is carried out using 1,3-specific lipase as a catalyst. The obtained oil and fat composition is medium-chain and long-chain triglycerides rich in Sn-2 palmitic acid. The acyl donor includes one or more of medium-chain fatty acids and / or free fatty acids of vegetable oil.

[0011] As a further preferred embodiment, the 1,3-specific lipase includes one or several of immobilized enzyme Lipozyme TLIL, Lipozyme RM IM, Novozyme 435, NS 40086, and Candida antarctica lipase.

[0012] As a further preferred embodiment, the solvent includes any one of ethyl acetate, n-hexane, and acetone.

[0013] As a further preferred embodiment, the free fatty acids of vegetable oil are derived from one or more of sunflower oil, high-oleic sunflower oil, and linseed oil; the medium-chain fatty acids are derived from lauric acid.

[0014] As a further preferred embodiment, in S1, the mass ratio of the cow milk fat to the solvent is 1:2 to 8; the stirring rate during crystallization is 2 r / min to 20 r / min; the crystallization time is 10 to 24 hours; the number of fractionation times during crystallization is 1 to 5 times, and the crystallization temperature is 0 to 30 °C.

[0015] As a further preferred embodiment, the acidolysis reaction time is 3 to 10 h; the reaction temperature of the acidolysis reaction is 50 °C to 70 °C; the molar ratio of the high-melting-point component of milk fat to the acyl donor is 1:4 to 10. Among them, the high-melting-point component of milk fat is an acyl acceptor, and an enzymatic acidolysis reaction is carried out with free fatty acids as the acyl donor to synthesize medium-chain and long-chain triglycerides rich in Sn-2 palmitic acid.

[0016] Thirdly, the present invention provides the use of the above-mentioned oil and fat composition of medium- and long-chain triglycerides in the preparation of foods and / or food additives.

[0017] As a further preferred embodiment, the foods include one or more of nutritional foods, foods for special medical purposes, infant formula milk powder, and senior foods.

[0018] The beneficial effects of the present invention are as follows.

[0019] (1) The present invention provides a method for efficiently and precisely enriching medium- and long-chain triglycerides from milk fat. By adding an appropriate amount of solvent as an auxiliary agent to improve the crystallization performance of milk fat, and then efficiently separating the medium- and long-chain triglyceride components in milk fat through stepwise cooling and crystallization cultivation, an oil and fat composition of natural milk source MLCT is obtained, realizing the efficient separation of MLCT in milk fat under mild conditions. Its MLCT content reaches more than 45%, and it can be used in ordinary foods, infant foods, and senior foods, etc., which can further improve the nutritional defects of milk fat and increase its economic value.

[0020] (2) The present invention provides a method for enzymatically preparing medium- and long-chain triglycerides of MLL type rich in Sn-2 palmitic acid. Using high-melting-point milk fat as an acyl acceptor, and using 1,3-specific lipase to catalyze the acidolysis reaction of acyl donor (free fatty acid) and acyl acceptor, so that the long-chain saturated fatty acids (palmitic acid and stearic acid, which are harmful to health) at the Sn-1,3 positions are replaced, thereby obtaining an oil and fat composition of medium- and long-chain triglycerides in which the Sn-1,3 positions are mainly distributed with medium-chain fatty acids and unsaturated fatty acids, the Sn-2 position is mainly distributed with palmitic acid, and the triglyceride configuration is mainly presented in the MLL configuration. Its MLCT content reaches more than 55%, and its fatty acid composition and structure are very similar to the MLCT composition in Chinese breast milk fat, having good nutritional and functional properties, and can be used in the formula design of infant milk powder to better simulate the breast milk fat composition. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 Shown is a broken line graph of the lipolysis degrees of different MLCT oil and fat compositions in the gastric stage and the small intestine stage; Figure 2The effects of different MLCT oil compositions on postprandial blood lipid indices are shown; where A is postprandial serum triglyceride, B is the area under the curve of postprandial serum triglyceride; C is postprandial serum total cholesterol, D is the level of postprandial serum low-density lipoprotein cholesterol; E is the level of postprandial serum high-density lipoprotein cholesterol, and F is the postprandial serum LDL / HDL ratio. Detailed implementation mode

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0024] Example 1 A preparation method of an oil composition of medium- and long-chain triglycerides, comprising the following steps: (1) Weigh 50 g of milk fat, melt it at 60 °C and keep it for 30 minutes to eliminate crystal memory. Add 10 g of acetone and mix well. Slowly cool it to 15 °C, continuously stir at 10 r / min, crystallize for 24 h and then centrifuge. Take the supernatant and continue to slowly cool it to 5 °C, continuously stir at 10 r / min, crystallize for 24 h and then centrifuge. The supernatant oil component is rotary evaporated to remove n-hexane to obtain natural milk source MLCT composition 1 (oil composition of milk source medium- and long-chain triglycerides); Combine the solid components obtained from the above two centrifugations, and rotary evaporate to remove n-hexane to obtain high-melting milk fat; (2) Weigh 20 g of the high-melting milk fat obtained in step (1) into a reaction flask, add free fatty acids and lauric acid prepared from sunflower oil, linseed oil and high-oleic sunflower oil, mix them in a molar ratio of 1:6 (the molar ratio of high-melting milk fat to free fatty acids), and add 10 wt% of Lipozyme RM IM enzyme. The reaction flask is filled with nitrogen and sealed, and stirred at 200 r / min in a 60 °C water bath for 4 h. The product is purified to obtain MLCT composition 2 rich in Sn-2 palmitic acid (oil composition of medium- and long-chain triglycerides of Sn-2 palmitic acid).

[0025] Example 2 A preparation method of an oil composition of medium- and long-chain triglycerides, comprising the following steps: (1) Weigh 50 g of milk fat, melt it at 60 °C and keep it warm for 30 minutes to eliminate crystal memory. After adding 10 g of n-hexane, mix well, slowly cool it to 20 °C, continuously stir at 20 r / min, crystalize for 12 h and then centrifuge. Continue to take the supernatant and slowly cool it to 5 °C, continuously stir at 20 r / min, crystalize for 12 h and then centrifuge. The supernatant oil is rotary evaporated to remove n-hexane to obtain natural milk source MLCT composition 3 (an oil composition of medium and long-chain triglycerides in milk source); Combine the solid components obtained from the above two centrifugations, and rotary evaporate to remove n-hexane to obtain high melting point milk fat; (2) Weigh 20 g of the high melting point milk fat obtained in step (1) into a reaction flask, and add free fatty acids and lauric acid prepared from sunflower oil, linseed oil and high oleic sunflower oil, and mix them in a molar ratio of 1:4 (the molar ratio of high melting point milk fat to free fatty acids). Add 8% of Lipozyme TL IM enzyme to it. The reaction flask is filled with nitrogen and sealed, and under a water bath at 55 °C, stir and react at 200 r / min for 6 h. The product is purified to obtain MLCT composition 4 rich in Sn-2 palmitic acid (an oil composition of medium and long-chain triglycerides of Sn-2 palmitic acid).

[0026] Example 3 A preparation method of an oil composition of medium and long-chain triglycerides, comprising the following steps: (1) Weigh 50 g of milk fat, melt it at 60 °C and keep it warm for 30 minutes to eliminate crystal memory. After adding 10 g of petroleum ether, mix well, slowly cool it to 20 °C, continuously stir at 20 r / min, crystalize for 24 h and then centrifuge. Continue to take the supernatant and slowly cool it to 5 °C, continuously stir at 20 r / min, crystalize for 24 h and then centrifuge. The supernatant oil is rotary evaporated to remove n-hexane to obtain natural milk source MLCT composition 5 (an oil composition of medium and long-chain triglycerides in milk source); Combine the solid components obtained from the above two centrifugations, and rotary evaporate to remove n-hexane to obtain high melting point milk fat; (2) Weigh 20 g of the high melting point milk fat obtained in step (1) into a reaction flask, and add free fatty acids and lauric acid prepared from sunflower oil, linseed oil and high oleic sunflower oil, and mix them in a molar ratio of 1:8 (the molar ratio of high melting point milk fat to free fatty acids). Add 8% of NS 40086 enzyme to it. The reaction flask is filled with nitrogen and sealed, and under a water bath at 65 °C, stir and react at 200 r / min for 5 h. The product is purified to obtain MLCT composition 6 rich in Sn-2 palmitic acid (an oil composition of medium and long-chain triglycerides of Sn-2 palmitic acid).

[0027] Comparative Example 1 A preparation method of an oil composition of medium and long-chain triglycerides, comprising the following steps: Mix the directly purchased medium-chain triglycerides with vegetable oil (rapeseed oil) evenly at a molar ratio of 1:9, then put them into a reactor, add 10 wt% of Novozyme 435 enzyme, seal the reaction flask with nitrogen, and stir and react at 60 °C in a water bath at 200 r / min for 4 h. Filter to remove the enzyme, purify the product, and obtain the MLCT composition 7.

[0028] Example 4 Determine the fatty acid and triglyceride compositions of the medium- and long-chain triglyceride oil compositions prepared in Examples 1-3 above. The fatty acid composition was determined by GC-FID (gas chromatography-flame ionization detector), and the triglyceride composition was determined by UPLC-ESI-Q-TOF-MS (ultra-high performance liquid chromatography-time of flight mass spectrometer).

[0029] The fatty acid composition of the oil composition of natural milk source medium- and long-chain triglycerides is shown in Table 1, and the triglyceride composition is shown in Table 2. The fatty acid composition of the oil composition of MLL-type medium- and long-chain triglycerides rich in Sn-2 palmitic acid is shown in Table 3, and the triglyceride composition is shown in Table 4.

[0030] Table 1 Fatty acid composition of the oil composition of natural milk source medium- and long-chain triglycerides (%) Table 2 Triglyceride composition of the oil composition of natural milk source medium- and long-chain triglycerides (%) Table 3 Fatty acid composition of the oil composition of Sn-2 palmitic acid medium- and long-chain triglycerides (%) Table 4 Triglyceride composition of the oil composition of Sn-2 palmitic acid medium- and long-chain triglycerides (%) Example 5 In vitro simulated digestibility determination Preparation of emulsion: First, dissolve a certain amount of emulsifier whey protein in ultrapure water, stir it in a constant temperature water bath to make it fully hydrated, then add appropriate amounts of Sn-2 palmitic acid medium- and long-chain triglycerides (compositions 2 / 4 / 6, H-MLCT) respectively, mix and stir for 5 min, then use high-speed shearing for 5 min, and then carry out homogenization treatment at 20 Mpa to obtain an emulsion. Natural milk source medium- and long-chain triglycerides (compositions 1 / 3 / 5, M-MLCT) and the long-chain triglyceride composition 7 (V-MLCT) in the control example were all prepared into homogeneous emulsions according to the above method, and all emulsions were prepared and used immediately.

[0031] In vitro digestion simulation of infants: Install the in vitro digestion model and the digestive fluid inlet pipeline, turn on the environmental heating and digestive fluid heating control to keep the temperature constant at 37 °C. Then add 50 mL of the initial emulsion preheated to 37 °C into the gastric reactor, and pump in the mixed gastric juice (pepsin and gastric lipase are 268 U / mL and 20 U / mL respectively, dissolved in simulated gastric juice; 0 - 1 min, 12.5 mL / min; 1 - 60 min, 0.4 mL / min; 60 - 120 min, 0.2 mL / min), control the gastric peristalsis at 3 times / min (forward speed 450 mm / min, return speed 450 mm / min) and the pylorus opening at 1 time / min (running speed 200 mm / min), and continuously control the left - right tilting angle of the stomach (0 - 2 min, 9 ° / min; 2 - 11 min, - 0.3 ° / min; 11 - 31 min, - 0.6 ° / min; 31 - 120 min, - 0.3 ° / min); pump in the mixed intestinal juice (bile salt concentration 3.1 mM, trypsin 4.5 U / mL, pancreatic lipase 90 U / mL, dissolved in simulated intestinal juice; 0 - 30 min, 1 mL / min; 30 - 60 min, 1.4 mL / min; 60 - 90 min, 1 mL / min; 90 - 120 min, 0.9 mL / min), control the duodenal valve to clamp for 4.9 min and then release for 0.1 min, and the duodenal extrusion device runs at 12 rpm / min. The in vitro gastric and small intestine digestion processes both last for 120 min. Gastric and small intestine digestion samples are taken at 30 min, 60 min, 90 min, and 120 min after the start of digestion, and the enzymes are inactivated in a 100 °C water bath for 5 min for extracting total lipids in the digestion products.

[0032] Total lipid extraction: Take 5 mL of the digest and 10 mL of methanol solution, vortex - mix for extraction for 2 - 3 min, then add 5 mL of ultrapure water and 5 mL of chloroform, vortex - mix again for extraction for 1 min, centrifuge at 3000 r / min for 5 min, take the lower chloroform layer, repeat the extraction for the upper aqueous phase once, combine the two chloroform layers, dry them under nitrogen, and store the obtained crude lipids at - 20 °C for subsequent analysis.

[0033] Lipid composition analysis: An appropriate amount of crude lipid was taken and dissolved in n-hexane to prepare a test sample solution with a concentration of about 5 mg / mL. After passing through a 0.22 μm filter membrane, the lipid composition was determined by liquid chromatography-evaporative light scattering detector. The chromatographic conditions were as follows: using a ZORBAX Eclipse XDB chromatographic column, column temperature 35 °C, injection volume 10 μL, flow rate 1 mL / min, mobile phase was acetonitrile (ACN) and dichloromethane (CH2Cl2), gradient elution: 0 - 12 min, 100% ACN; 12 - 20 min, 100% - 70% ACN; 20 - 26 min, 70% ACN; 26 - 35 min, 70% - 30% ACN; 35 - 37 min, 30% ACN; the drift tube temperature of the evaporative light scattering detector was 85 °C, and the nitrogen flow rate was 2.0 mL / min. The results were expressed as the percentage of the relative content of each type of lipid, and then the average relative molecular mass was calculated based on the fatty acid composition of the sample, and the data was converted into relative molar content. The degree of lipolysis of triglycerides during digestion was expressed as the molar percentage of free fatty acids in the total lipids of the digestive fluid: Among them, [TAG], [DAG], [MAG], and [FFA] represent the molar contents of various lipids respectively.

[0034] The results were as Figure 1 shown: From the graph of the change in the digestion rate at each stage during in vitro simulated digestion, it can be seen that the digestion rates of the emulsions of each composition were similar during the gastric digestion stage. At the end of gastric digestion, the degree of lipolysis of natural milk source MLCT was the highest, indicating that its digestion rate was the fastest; while during the small intestine digestion stage, the digestion rates of natural milk source MLCT and Sn-2 palmitic acid MLCT were significantly higher than that of Composition 7, indicating that their digestion rates in the small intestine were faster and their bioavailability was higher, achieving the goal of rapid energy supply, which highlights their great application potential in functional foods, such as in the fields of senior foods and infant formula foods.

[0035] Example 6 Determination of postprandial blood lipids Twenty-four male C57 BL / 6J neonatal mice (3 weeks old) of the clean grade were housed in the clean-grade experimental animal center at a temperature of (25±2°C) and a humidity of 50%. They had free access to water and food. The care and pretreatment of the experimental animals were carried out in accordance with the relevant regulations of the "Regulations on the Administration of Experimental Animals". After being fed with the basal diet for one week, the mice were randomly divided into 4 groups: the basal control group (Con), the natural milk source MLCT oil composition group (M-MLCT), the Sn-2 palmitic acid MLCT oil composition group (H-MLCT), and the MLCT oil composition group of the comparative example (V-MLCT). Equal volumes of MLCT oil compositions were gavaged to the mice in each group, and the basal control group was gavaged with an equal volume of normal saline. After the gavage operation was completed, blood was collected by eye puncture at different time points (0, 0.5, 1, 2, 3, 4, 5 h). The blood was centrifuged at 3000 rpm for 15 min at 4°C, and the upper-layer serum was collected and stored at -80°C for the determination of TG, TC, LDL, and HDL to evaluate its effect on postprandial blood lipids.

[0036] The results are as Figure 2 shown. From the perspective of postprandial blood lipid indices, the effects of different MLCTs on postprandial blood lipids are different. Compared with the MLCT oil composition prepared in Comparative Example 7, the oil compositions of milk source MLCT and MLCT rich in Sn-2 palmitic acid prepared according to the present invention have significantly higher areas under the serum triglyceride curve, indicating that more fatty acids are absorbed into the blood by the small intestine. This result is consistent with the in vitro digestion result, indicating that the MLCT prepared by the present invention is more easily digested and absorbed by the gastrointestinal tract and has higher bioavailability. The effect of MLCT on postprandial total serum cholesterol is not obvious, while the oil composition of milk source MLCT prepared by the present invention is more likely to cause an increase in postprandial LDL level and a decrease in HDL level, which may be related to its higher content of long-chain saturated fatty acids. Its physiological effects need further study.

[0037] The embodiments of the present application have been described above in conjunction with the accompanying drawings. Specific examples have been used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the core idea of the present application. However, the present application is not limited to the above specific implementation manners. The above specific implementation manners are only illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection scope of the present application.

Claims

1. An oil and fat composition of medium and long-chain triglycerides, characterized in that, The fat composition includes a fat composition of milk-source medium and long-chain triglycerides and / or a fat composition of medium and long-chain triglycerides rich in Sn-2 palmitic acid; The fat composition of milk-source medium and long-chain triglycerides is a pure natural fat composition of medium and long-chain triglycerides. Among them, the content ratio of medium-chain fatty acids to long-chain fatty acids is 0.9~1:9~9.1, and the content of unsaturated fatty acids exceeds 40%; in terms of triglyceride composition, triglycerides containing one medium-chain fatty acid account for 30%~40% of the total triglyceride content, triglycerides containing two medium-chain fatty acids account for 5%~10% of the total triglyceride content, and triglycerides containing three medium-chain fatty acids account for 10%~15% of the total triglyceride content; In the fat composition of medium and long-chain triglycerides rich in Sn-2 palmitic acid, the content ratio of medium-chain fatty acids to long-chain fatty acids is 1~1.2:8.8~9, the ratio of n-6 / n-3 polyunsaturated fatty acids is 4~6, the content of saturated fatty acids at the Sn-2 position is more than 75%, and the content of palmitic acid exceeds 45%; in terms of triglyceride composition, triglycerides containing one medium-chain fatty acid account for 40%~60% of the total triglyceride content, triglycerides containing two medium-chain fatty acids account for 5%~10% of the total triglyceride content, and triglycerides containing three medium-chain fatty acids account for less than 3% of the total triglyceride content.

2. The fat and oil composition according to claim 1, wherein Both the medium-chain fatty acids and long-chain fatty acids in the fat composition of milk-source medium and long-chain triglycerides are derived from milk fat; The medium-chain fatty acids and long-chain fatty acids in the fat composition of medium and long-chain triglycerides rich in Sn-2 palmitic acid are derived from vegetable oil, milk fat and lauric acid.

3. The preparation method of the oil and fat composition of medium and long-chain triglycerides according to any one of claims 1-2, characterized in that, It includes the following steps: S1: After heating and melting milk fat, it is mixed evenly with a solvent, and gradually cooled for crystallization. Through specific enrichment, a fat composition of milk-source medium and long-chain triglycerides is prepared, and at the same time, the high-melting-point component of milk fat is separated; S2: The high-melting-point component of milk fat separated in step S1 is mixed with an acyl donor, and an acidolysis reaction is carried out using 1,3-specific lipase as a catalyst to obtain a fat composition of medium and long-chain triglycerides of Sn-2 palmitic acid. The acyl donor includes one or more of medium-chain fatty acids and / or vegetable oil free fatty acids.

4. The preparation method according to claim 3, wherein The 1,3-specific lipase includes one or several of immobilized enzyme Lipozyme TL IL, Lipozyme RM IM, Novozyme 435, NS 40086, and Candida antarctica lipase.

5. The preparation method according to claim 3, wherein The solvent includes any one of ethyl acetate, n-hexane, and acetone.

6. The preparation method according to claim 3, characterized in that, The vegetable oil free fatty acids are derived from one or more of sunflower oil, high-oleic sunflower oil, and linseed oil; the medium-chain fatty acids are derived from lauric acid.

7. The preparation method according to claim 3, characterized in that, In S1, the mass ratio of the milk fat to the solvent is 1:2~8; the stirring rate during crystallization is 2 r / min~20 r / min; the crystallization time is 10~24 hours; the number of fractionation times during crystallization is 1~5 times, and the crystallization temperature is 0~30°C.

8. The preparation method according to claim 3, wherein The acidolysis reaction time is 3 to 10 h; the reaction temperature of the acidolysis reaction is 50 °C to 70 °C; the molar ratio of the high melting point component of milk fat to the acyl donor is 1:4 to 1:

10.

9. Use of the oil and fat composition of medium and long chain triglycerides according to any one of claims 1-2 in the preparation of food and / or food additives.

10. The application according to claim 9, characterized in that, The food includes one or more of nutritional food, special medical food, infant formula, and senior food.

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