Purification method of lutein ester with low viscosity and high melting point

Abstract

The invention discloses a purification method of low-viscosity and high-melting-point lutein ester, and belongs to the technical field of lutein ester purification. The purification method comprises the following steps: carrying out enzymolysis treatment on lutein ester extract by using a complex enzyme aqueous solution to obtain an enzymolysis reaction solution; after the enzymatic hydrolysis reaction liquid is subjected to standing layering, taking supernatant liquid, mixing the supernatant liquid with an alcohol solution, adding basic salt, and carrying out a neutralization reaction to obtain a neutralization reaction liquid; and cooling, crystallizing and filtering the neutralization reaction liquid, taking a crystal solid, repeatedly crystallizing twice by using an alcoholic solution, and drying to obtain a purified finished product of the lutein ester. According to the method disclosed by the invention, sticky and low-melting-point vegetable fat components in the lutein ester extract can be greatly removed, the viscosity of a lutein ester product can be effectively reduced, the properties of the product can be improved, the melting point of the product can be increased, and the problems of difficulty in drying, difficulty in crushing and the like are solved, so that the quality of the lutein ester product is improved, and related application of the lutein ester product is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of lutein ester purification, in particular to a method for purifying lutein ester with low viscosity and high melting point. Background Art

[0002] Currently, the main methods for purifying lutein esters include mixed solvent washing, resin adsorption purification, and mixed solvent crystallization. However, these methods do not address the stickiness of lutein ester products and the difficulty of drying and pulverizing due to low-melting-point impurities. Lutein ester extracts contain a large amount of plant fat (fatty acids, glycerol, and glycerides), which is the primary cause of the stickiness of lutein ester products. Since plant fats and lutein esters have similar polarity, currently used lutein ester purification methods struggle to remove plant fats, resulting in stickiness and caking of lutein ester products. Plant fats have low melting points, mostly between 40 and 80°C, making lutein ester products difficult to dry and pulverize. As the temperature rises, the products tend to melt, making them difficult to store and limiting their application. Therefore, there is an urgent need to develop a method that can significantly remove plant fat from lutein esters, reduce their viscosity, increase their melting point, and facilitate their application. Summary of the Invention

[0003] The present invention aims to provide a method for purifying low-viscosity, high-melting-point lutein esters to address the problems of the prior art. The present invention utilizes a method of complex enzyme degradation of glycerides, neutralization of fatty acids with alkaline salts, and subsequent removal of fatty acids through crystallization. This method can significantly remove the sticky, low-melting-point plant fat components in lutein ester extracts, effectively reducing the viscosity of the lutein ester product, improving its properties, raising its melting point, and resolving issues such as difficulty drying and pulverizing. This method, therefore, improves the quality of the lutein ester product and promotes its related applications.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a method for purifying a low-viscosity, high-melting-point lutein ester, comprising the following steps:

[0006] (1) enzymatically hydrolyzing the lutein ester extract using a complex enzyme aqueous solution to obtain an enzymatic hydrolysis reaction solution;

[0007] (2) After the enzymatic hydrolysis reaction solution is allowed to stand and separate, the supernatant is taken, mixed with the alcohol solution, and then an alkaline salt is added to carry out a neutralization reaction to obtain a neutralized reaction solution;

[0008] (3) cooling the neutralization reaction solution to crystallize, filtering, taking the crystalline solid, repeating the crystallization twice with an alcohol solution, and drying to obtain a purified lutein ester product;

[0009] The complex enzyme aqueous solution contains hormone-sensitive lipase and monoacylglycerol lipase.

[0010] Optionally, in step (1), the concentration of the complex enzyme aqueous solution is 15-25 mg / ml; the mass volume ratio of the lutein ester extract and the complex enzyme aqueous solution is 1 kg:80-150 ml.

[0011] Optionally, the mass ratio of the hormone-sensitive lipase to monoacylglycerol lipase is 1:3-4.

[0012] Optionally, in step (1), the temperature of the enzymatic hydrolysis treatment is 50-55° C. and the time is 5-6 h.

[0013] Optionally, in step (2), the alcohol solution includes an ethanol aqueous solution; the volume fraction of the ethanol aqueous solution is 90%-97%; and the volume mass ratio of the ethanol aqueous solution to the lutein ester extract is 8-12L:1kg.

[0014] Optionally, in step (2), the alkaline salt includes one or more of sodium carbonate, sodium bicarbonate, potassium carbonate and calcium carbonate;

[0015] The mass ratio of the alkaline salt to the lutein ester extract is 50-60g:1kg.

[0016] Optionally, in step (2), the neutralization reaction temperature is 50-60° C. and the time is 4-5 h.

[0017] Optionally, in step (3), the terminal temperature of the cooling crystallization is 17-18°C;

[0018] The alcohol solution includes an ethanol-water solution; the process of repeating crystallization twice using the alcohol solution is: mixing the crystalline solid with an alcohol solution with a volume fraction of 90%-97%, stirring for 0.5-3 hours, filtering, and obtaining a second crystalline solid; mixing the second crystalline solid with an alcohol solution with a volume fraction of 90%-97%, stirring for 0.5-3 hours, filtering, and obtaining a third crystalline solid.

[0019] Optionally, the volume mass ratio of the alcohol solution to the lutein ester extract during the preparation of the second crystallization solid is 3-5 L: 1 kg;

[0020] The volume mass ratio of the alcohol solution to the lutein ester extract during the preparation of the third crystallization solid is 1-2 L:1 kg.

[0021] Optionally, the lutein ester extract includes a heating and melting step before being subjected to the enzymatic hydrolysis treatment.

[0022] The present invention discloses the following technical effects:

[0023] The present invention adopts a method of composite enzyme degradation of glyceride - alkaline salt neutralization of fatty acid - crystallization to remove fatty acid, thereby removing the sticky and low-melting-point plant fat components in the lutein ester extract, effectively reducing the viscosity of the lutein ester product, improving product properties, increasing the product melting point, and solving the problems of difficult drying and difficult crushing.

[0024] The method of the present invention has the advantage of being simple to operate, significantly reducing the difficulty of production operations and facilitating industrial production. The resulting lutein ester yield is high, 10%-20% higher than that of traditional methods. The lutein ester prepared by the method of the present invention has a long shelf life, good stability, and complete stability data, facilitating the application of lutein ester products in food, health products, and cosmetics. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is a diagram showing the appearance and properties of the finished product of lutein ester prepared in Example 3;

[0027] Figure 2 This is a diagram of the appearance of the lutein ester finished product prepared in Comparative Example 1. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] The technical ideas of the present invention are as follows:

[0034] In order to remove the vegetable fat in the product, change the viscosity of the product and solve the problem of low melting point, the previous research of this invention tried to neutralize fatty acids with alkali, neutralize fatty acids with alkaline salts and degrade vegetable fat with enzymes.

[0035] Alkali neutralization of fatty acids: Alkali neutralization can remove fatty acids in the product, but at the same time, lutein esters will undergo saponification reaction to produce lutein, reducing the lutein ester content in the product.

[0036] Enzymatic degradation of vegetable fats: By screening for specific enzymes that selectively and specifically degrade glycerides into fatty acids and glycerol, facilitating their removal in subsequent processes, we ultimately identified enzymes with strong selectivity for glyceride degradation: HSL hormone-sensitive lipase and MGL monoacylglycerol lipase, which are combined to degrade glycerides while preserving the active ingredient, lutein esters.

[0037] Neutralization of fatty acids with alkaline salts: Neutralization of alkaline salts can effectively remove fatty acids from the product. At the same time, its weak alkalinity will not damage lutein esters, and can successfully solve the problem of product stickiness and difficulty in drying and crushing due to low melting point.

[0038] The specific process of the present invention is as follows: heating and melting a lutein ester extract (lutein ester UV content 20%), adding a composite lipase aqueous solution and keeping the temperature to carry out enzymatic hydrolysis reaction (enzymatic hydrolysis of glycerol ester into fatty acids and glycerol), taking the upper liquid after the reaction, adding an ethanol solution, heating and stirring to dissolve, adding an alkaline salt (one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, and calcium carbonate), heating and stirring to react (to convert fatty acids into alcohol-soluble fatty acid salts, which are subsequently crystallized and removed), cooling and crystallizing to precipitate lutein ester crystals, and then washing the lutein ester crystals with ethanol to obtain a high-content lutein ester product (lutein ester UV content ≥90%).

[0039] In the following examples, lutein ester extract was purchased from Yunnan Ruibao Biotechnology Co., Ltd.; HSL hormone-sensitive lipase and MGL monoacylglycerol lipase were purchased from Qingdao Weilan Biotechnology Co., Ltd.

[0040] In the following examples, the lutein ester content in the lutein ester extract is expressed as mass fraction T, and the value is expressed in %, and is calculated according to the following formula:

[0041]

[0042] Where: T is the lutein ester content, %; A is the absorbance of the sample; D is the dilution factor of the sample; m is the mass of the sample, g.

[0043] The lutein ester content in the lutein ester powder sample is expressed as mass fraction T, and the value is expressed in %, and is calculated according to the following formula:

[0044]

[0045] Where: T is the lutein ester content, %; A is the absorbance of the sample; D is the dilution factor of the sample; m is the mass of the sample, g.

[0046] Example 1

[0047] This embodiment provides a method for purifying lutein esters, and the specific process is as follows:

[0048] (1) 1 kg of lutein ester extract was added to a reactor (the content of lutein ester in the lutein ester extract was 19.8 mg / 100 mg), heated to 50°C, and stirred to dissolve. 100 ml of a 20 mg / ml aqueous solution of a complex enzyme (HSL hormone-sensitive lipase: MGL monoacylglycerol lipase, mass ratio = 1:3) was added to the reactor, and the mixture was stirred at 50°C for 5 h to obtain a reaction solution.

[0049] (2) After the reaction solution was allowed to stand and separate, the upper layer was collected and added to a reaction kettle. 10 L of a 95 vol.% ethanol aqueous solution was added to the reaction kettle, heated to 60°C, and stirred to dissolve. 50 g of solid sodium carbonate was added to the reaction solution, and the mixture was stirred at 60°C for 4 h. While stirring, the mixture was cooled and crystallized. The cooling time was 16 h, and the final temperature was 18°C.

[0050] (3) Filter and take the crystalline solid, add the crystalline solid to a reactor, add 4 L of a 95 vol.% ethanol aqueous solution to the reactor, and stir at room temperature for 30 min. Filter again, take the crystalline solid, add the crystalline solid to a reactor, and then add 2 L of a 95 vol.% ethanol aqueous solution to the reactor, and stir at room temperature for 30 min. Filter a third time, take the crystalline solid, and dry it under reduced pressure at 60°C to obtain the finished lutein ester.

[0051] The final lutein ester product weighed 186 g. The lutein ester content was determined by UV-visible spectrophotometry to be 96.7 mg / 100 mg. The lutein ester yield was 90.8% ((0.186 kg x 96.7%) / (1 kg x 19.8%) x 100%).

[0052] Example 2

[0053] This embodiment provides a method for purifying lutein esters, and the specific process is as follows:

[0054] (1) 5 kg of lutein ester extract (the content of lutein ester in the lutein ester extract is 19.8 mg / 100 mg) was added to a reactor, heated to 55°C, and stirred to dissolve. 500 ml of a 20 mg / ml aqueous solution of a complex enzyme (HSL hormone-sensitive lipase: MGL monoacylglycerol lipase mass ratio = 1:3.5) was added to the reactor, and the mixture was stirred at 55°C for 6 h to obtain a reaction solution.

[0055] (2) After the reaction solution was allowed to stand and separate, the upper layer was collected and added to a reactor. 50 L of a 95 vol.% ethanol aqueous solution was added to the reactor, heated to 55°C, and stirred to dissolve. 300 g of solid sodium carbonate was added to the reaction solution, and the mixture was stirred at 60°C for 4 h. While stirring, the mixture was cooled and crystallized for 20 h, with the final temperature being 17°C.

[0056] (3) Filter, take the crystalline solid, put it into a reactor, add 20 L of 95 vol.% ethanol aqueous solution into the reactor, and stir at room temperature for 1 hour. Filter again, take the crystalline solid, put it into a reactor, and add 10 L of 95 vol.% ethanol aqueous solution into the reactor, and stir at room temperature for 1 hour. Filter a third time, take the crystalline solid, and dry it under reduced pressure at 60°C to obtain the finished lutein ester.

[0057] The final lutein ester product weighed 919 g. The lutein ester content was determined by UV-visible spectrophotometry to be 97.2 mg / 100 mg. The lutein ester yield was 90.2% ((0.919 kg x 97.2%) / (5 kg x 19.8%) x 100%).

[0058] Example 3

[0059] This embodiment provides a method for purifying lutein esters, and the specific process is as follows:

[0060] (1) 200 kg of lutein ester extract (the content of lutein ester in lutein ester extract is 19.8 mg / 100 mg) was added to a reactor, heated to 55°C, and stirred to dissolve. 20 L of a 20 mg / ml aqueous solution of a complex enzyme (HSL hormone-sensitive lipase: MGL monoacylglycerol lipase, mass ratio = 1:3.5) was added to the reactor, and the mixture was stirred at 55°C for 6 h.

[0061] (2) The reaction solution was allowed to stand for stratification. The upper layer was taken and added to a reactor. 2000 L of 95 vol.% ethanol aqueous solution was then added to the reactor, heated to 60°C, and stirred to dissolve. 10 kg of solid sodium carbonate was added to the reaction solution, and the mixture was stirred at 60°C for 5 h. While stirring, the mixture was cooled and crystallized. The cooling time was 26 h, and the final temperature was 18°C.

[0062] (3) Filter, take the crystalline solid, put the crystalline solid into the reactor, add 800L of 95vol.% ethanol aqueous solution into the reactor, and stir at room temperature for 2h. Filter again, take the crystalline solid, put the crystalline solid into the reactor, and then add 400L of 95vol.% ethanol aqueous solution into the reactor, and stir at room temperature for 2h. Filter for the third time, take the crystalline solid, and dry the crystalline solid at 60℃ under reduced pressure to obtain the finished lutein ester. Its appearance is as follows Figure 1 shown.

[0063] The final lutein ester product weighed 37.2 kg. The lutein ester content was determined by UV-visible spectrophotometry to be 96.5 mg / 100 mg. The lutein ester yield was 90.6% ((37.2 kg x 96.5%) / (200 kg x 19.8%) x 100%).

[0064] Comparative Example 1

[0065] (1) Dissolve 100 g of lutein ester extract in 300 ml of tetrahydrofuran and stir to form a uniform solution x.

[0066] (2) Filter the solution x at 50° C. to obtain a filtrate.

[0067] (3) Add 700 ml of deionized water to the filtrate of step (2), stir for 4 h, and filter again to obtain crystal y.

[0068] (4) Wash crystal y with deionized water until the deionized water flowing out after washing is colorless.

[0069] (5) After washing, the crystals are placed in a vacuum and dried for 2 days to obtain the finished product of lutein ester. Its appearance and properties are as follows Figure 2 shown.

[0070] The final lutein ester product weighed 26.6 g. The lutein ester content was determined by UV-visible spectrophotometry to be 60.7 mg / 100 mg. The lutein ester yield was 81.5% ((26.6 g x 60.7%) / (100 g x 19.8%) x 100%).

[0071] Comparative Example 2

[0072] (1) Mix 100 g of lutein ester extract with 300 ml of acetone and stir at 50°C for 30 min to dissolve it.

[0073] (2) The reaction solution was slowly cooled to 20°C and centrifuged to remove insoluble matter.

[0074] (3) The supernatant was centrifuged and concentrated under reduced pressure to obtain a concentrate of the acetone-soluble portion.

[0075] (4) Add 350 ml of n-butanol to the concentrate obtained in step (3) and stir at 50°C to dissolve the concentrate.

[0076] (5) The reaction solution was slowly cooled to 4°C, then placed at 4°C for 16 h and filtered.

[0077] (6) Mix the filtered solid from step (5) with 200 ml of ethanol. Stir the mixture to disperse it, and then filter it.

[0078] (7) The solid obtained in step (6) is filtered and vacuum dried to remove the residual solvent to obtain the finished product lutein ester.

[0079] The final lutein ester product weighed 17.6 g. The lutein ester content was determined by UV-visible spectrophotometry to be 84.9 mg / 100 mg. The lutein ester yield was 58.3% ((13.6 g x 84.9%) / (100 g x 19.8%) x 100%).

[0080] Comparative Example 3

[0081] (1) 1 kg of lutein ester extract (the content of lutein ester in the lutein ester extract is 19.8 mg / 100 mg) was added to a reactor, heated to 50°C, and stirred to dissolve. 100 ml of a 20 mg / ml HSL hormone-sensitive lipase aqueous solution was added to the reactor, and the mixture was stirred at 50°C for 5 h to obtain a reaction solution.

[0082] (2) After the reaction solution was allowed to stand and separate, the upper layer was collected and added to a reaction kettle. 10 L of a 95 vol.% ethanol aqueous solution was added to the reaction kettle, heated to 60°C, and stirred to dissolve. 50 g of solid sodium carbonate was added to the reaction solution, and the mixture was stirred at 60°C for 4 h. While stirring, the mixture was cooled and crystallized. The cooling time was 16 h, and the final temperature was 18°C.

[0083] (3) Filter and take the crystalline solid, add the crystalline solid to a reactor, add 4 L of a 95 vol.% ethanol aqueous solution to the reactor, and stir at room temperature for 30 min. Filter again, take the crystalline solid, add the crystalline solid to a reactor, and then add 2 L of a 95 vol.% ethanol aqueous solution to the reactor, and stir at room temperature for 30 min. Filter a third time, take the crystalline solid, and dry it under reduced pressure at 60°C to obtain the finished lutein ester.

[0084] The final lutein ester product weighed 227 g. The lutein ester content was determined by UV-visible spectrophotometry to be 78.4 mg / 100 mg. The lutein ester yield was 89.9% ((227 g x 78.4%) / (1 kg x 19.8%) x 100%).

[0085] Comparative Example 4

[0086] (1) 1 kg of lutein ester extract (the content of lutein ester in the lutein ester extract is 19.8 mg / 100 mg) was added to a reactor, heated to 50°C, and stirred to dissolve. 100 ml of a 20 mg / ml aqueous solution of MGL monoacylglycerol lipase was added to the reactor, and the mixture was stirred at 50°C for 5 h to obtain a reaction solution.

[0087] (2) After the reaction solution was allowed to stand and separate, the upper layer was collected and added to a reaction kettle. 10 L of a 95 vol.% ethanol aqueous solution was added to the reaction kettle, heated to 60°C, and stirred to dissolve. 50 g of solid sodium carbonate was added to the reaction solution, and the mixture was stirred at 60°C for 4 h. While stirring, the mixture was cooled and crystallized. The cooling time was 16 h, and the final temperature was 18°C.

[0088] (3) Filter and take the crystalline solid, add the crystalline solid to a reactor, add 4 L of a 95 vol.% ethanol aqueous solution to the reactor, and stir at room temperature for 30 min. Filter again, take the crystalline solid, add the crystalline solid to a reactor, and then add 2 L of a 95 vol.% ethanol aqueous solution to the reactor, and stir at room temperature for 30 min. Filter a third time, take the crystalline solid, and dry it under reduced pressure at 60°C to obtain the finished lutein ester.

[0089] The final lutein ester product weighed 203 g. The lutein ester content was determined by UV-visible spectrophotometry to be 84.4 mg / 100 mg. The lutein ester yield was 86.5% ((203 g x 84.4%) / (1 kg x 19.8%) x 100%).

[0090] Comparative Example 5

[0091] (1) 1 kg of lutein ester extract (the lutein ester content in the lutein ester extract is 19.8 mg / 100 mg) was added to a reactor, heated to 50°C, and stirred to dissolve. 100 ml of a 20 mg / ml Pseudomonas lipase solution was added to the reactor, and the mixture was stirred at 50°C for 5 h to obtain a reaction solution.

[0092] (2) After the reaction solution was allowed to stand and separate, the upper layer was collected and added to a reaction kettle. 10 L of a 95 vol.% ethanol aqueous solution was added to the reaction kettle, heated to 60°C, and stirred to dissolve. 50 g of solid sodium carbonate was added to the reaction solution, and the mixture was stirred at 60°C for 4 h. While stirring, the mixture was cooled and crystallized. The cooling time was 16 h, and the final temperature was 18°C.

[0093] (3) Filter and take the crystalline solid, add the crystalline solid to a reactor, add 4 L of a 95 vol.% ethanol aqueous solution to the reactor, and stir at room temperature for 30 min. Filter again, take the crystalline solid, add the crystalline solid to a reactor, and then add 2 L of a 95 vol.% ethanol aqueous solution to the reactor, and stir at room temperature for 30 min. Filter a third time, take the crystalline solid, and dry it under reduced pressure at 60°C to obtain the finished lutein ester.

[0094] The final lutein ester product weighed 228 kg. The lutein ester content was determined by UV-visible spectrophotometry to be 72.3 mg / 100 mg. The lutein ester yield was 83.3% ((228 g x 72.3%) / (1 kg x 19.8%) x 100%).

[0095] Test Example 1

[0096] The lutein ester content and yield in the lutein ester finished products of Examples 1-3 and Comparative Examples 1-5 were statistically analyzed, and the results are shown in Table 1. As can be seen from Table 1, the purification method of the present invention can achieve a lutein ester content of more than 96% in the lutein ester finished product, and a lutein ester yield of more than 90%, which is significantly improved compared with the prior art method; the results of Example 1 and Comparative Examples 3-5 show that the combined use of the hormone-sensitive lipase and monoacylglycerol lipase screened by the present invention has a significant effect on the purification effect of lutein ester. Figure 1 and Figure 2 It can be seen that the lutein ester product prepared by the purification method of the present invention has a finer and looser powder texture and lower viscosity, and its product properties are significantly better than those of the lutein ester product prepared by the prior art method.

[0097] Table 1 Lutein ester content test results

[0098]

[0099] Test Example 2

[0100] The melting points of the lutein ester products of Examples 1-3 and Comparative Examples 1-5 were statistically analyzed, and the results are shown in Table 2. As can be seen from Table 2, the purification method of the present invention can achieve a melting point of lutein ester products above 73°C, which is significantly higher than that of the prior art methods.

[0101] Table 2 Lutein ester sample melting point test results

[0102] Sample name Melting point Example 1 finished product 73.32～74.05℃ Example 2 finished product 73.30～74.13℃ Example 3 finished product 73.35～74.08℃ Comparative Example 1 Finished Product 48.37～50.08℃ Comparative Example 2 finished product 64.33～66.01℃ Comparative Example 3 finished product 59.64～61.12℃ Comparative Example 4 Finished Product 63.87～64.00℃ Comparative Example 5 Finished Product 54.36～55.97℃

[0103] Test Example 3

[0104] Accelerated tests and long-term stability tests were performed on the lutein ester product of Example 3.

[0105] Accelerated experiment: Expose one lutein ester sample to air and test the lutein ester content in the sample at 0 hours, 8 hours, 24 hours, 2 days, 3 days, 7 days, 14 days, 21 days, 1 month, 2 months, and 3 months. Observe the degradation trend of the lutein ester content and infer the shelf life of the product.

[0106] Long-term stability experiment: One portion of lutein ester sample was vacuum packed and stored, and samples were taken regularly to detect the lutein ester content. The sampling time was: 0 hour, 7 days, 1 month, 3 months, 6 months, 1 year, 1.5 years, 2 years, and 3 years. The degradation trend of the lutein ester content was observed to determine the shelf life of the product.

[0107] The results are shown in Table 3. As can be seen from Table 3, the degradation rate of lutein esters in vacuum packaging and stored in an appropriate temperature and humidity environment is 0.42% after 3 years of storage, which is within an acceptable range.

[0108] Table 3 Lutein ester stability test results

[0109]

[0110]

[0111] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for purifying a low-viscosity, high-melting-point lutein ester, characterized in that: The steps include: (1) enzymatically hydrolyzing the lutein ester extract using a complex enzyme aqueous solution to obtain an enzymatic hydrolysis reaction solution; (2) After the enzymatic hydrolysis reaction solution is allowed to stand and separate, the supernatant is taken, mixed with the alcohol solution, and then an alkaline salt is added to carry out a neutralization reaction to obtain a neutralized reaction solution; (3) cooling the neutralization reaction solution to crystallize, filtering, taking the crystalline solid, repeating the crystallization twice with an alcohol solution, and drying to obtain a purified lutein ester product; The complex enzyme aqueous solution contains hormone-sensitive lipase and monoacylglycerol lipase.

2. The purification method according to claim 1, wherein In step (1), the concentration of the complex enzyme aqueous solution is 15-25 mg / ml; the mass volume ratio of the lutein ester extract to the complex enzyme aqueous solution is 1 kg:80-150 ml.

3. The purification method according to claim 1, wherein The mass ratio of the hormone-sensitive lipase to the monoacylglycerol lipase is 1:3-4.

4. The purification method according to claim 1, wherein In step (1), the temperature of the enzymatic hydrolysis treatment is 50-55° C. and the time is 5-6 h.

5. The purification method according to claim 1, wherein In step (2), the alcohol solution includes an ethanol aqueous solution; the volume fraction of the ethanol aqueous solution is 90%-97%; and the volume mass ratio of the ethanol aqueous solution to the lutein ester extract is 8-12L:1kg.

6. The purification method according to claim 1, wherein In step (2), the alkaline salt includes one or more of sodium carbonate, sodium bicarbonate, potassium carbonate and calcium carbonate; The mass ratio of the alkaline salt to the lutein ester extract is 50-60g:1kg.

7. The purification method according to claim 1, characterized in that In step (2), the neutralization reaction temperature is 50-60° C. and the time is 4-5 h.

8. The purification method according to claim 1, wherein In step (3), the terminal temperature of the cooling crystallization is 17-18°C; The alcohol solution includes an ethanol-water solution; the process of repeating crystallization twice using the alcohol solution is: mixing the crystalline solid with an alcohol solution with a volume fraction of 90%-97%, stirring for 0.5-3 hours, filtering, and obtaining a second crystalline solid; mixing the second crystalline solid with an alcohol solution with a volume fraction of 90%-97%, stirring for 0.5-3 hours, filtering, and obtaining a third crystalline solid.

9. The purification method according to claim 8, characterized in that The volume mass ratio of the alcohol solution to the lutein ester extract during the second crystallization solid preparation is 3-5 L: 1 kg; The volume mass ratio of the alcohol solution to the lutein ester extract during the preparation of the third crystallization solid is 1-2 L:1 kg.

10. The purification method according to claim 1, characterized in that The lutein ester extract comprises a heating and melting step before being subjected to the enzymatic hydrolysis treatment.

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