Method for preparing high-purity coconut oil diglyceride based on multi-stage distillation and application thereof
By employing a multi-stage molecular distillation method and a temperature gradient control of low temperature-high temperature-low temperature, the solidification and thermal decomposition problems of coconut oil diglycerides have been solved, enabling the preparation of high-purity and high-yield coconut oil diglycerides, which are suitable for functional oils, health products, and pharmaceuticals.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-13
- Publication Date
- 2026-04-10
AI Technical Summary
Existing technologies struggle to effectively address the coagulation and thermal decomposition issues of coconut oil diglycerides during molecular distillation, leading to decreased product purity and yield. Furthermore, existing methods fail to balance efficient separation with purity requirements.
A multi-stage molecular distillation method is employed, which uses a temperature gradient control of low temperature-high temperature-low temperature, combined with a specific vacuum level, to perform first-stage, second-stage, and third-stage molecular distillation. The temperature is controlled between the freezing point of coconut oil and the evaporation and decomposition temperature of diglycerides, respectively, to achieve efficient separation and purification.
High-purity (≥90%) coconut oil diglycerides were prepared. The product has good color, few by-products, and high yield, making it suitable for industrial production and simplifying equipment control and energy consumption.
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Figure CN121824311A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of oil preparation technology, specifically relating to a method for preparing high-purity coconut oil diglycerides based on multi-stage distillation and its application. Background Technology
[0002] Diglycerides, especially 1,3-diglycerides, are recognized as functional lipids, and studies have shown that they possess unique effects such as inhibiting fat accumulation and lowering blood lipids. Coconut oil is highly favored due to its rich content of easily metabolized and rapidly energy-providing medium-chain fatty acids. Combining the advantages of both, developing coconut oil diglyceride products that combine health benefits with rapid energy delivery has broad market prospects in the functional food, health product, and pharmaceutical fields.
[0003] The efficient separation and purification of diglycerides from transesterification products or natural oils is a core step in achieving their industrialization. Among the many existing separation technologies, molecular distillation is considered one of the preferred methods for the industrial purification of heat-sensitive diglycerides due to its outstanding advantages such as low operating temperature, short material heating time, and high separation efficiency. However, when specifically applied to the purification of coconut oil diglycerides, molecular distillation technology faces two interconnected and difficult-to-balance technical bottlenecks, constituting the main obstacles to industrialization: 1. The problem of material flowability caused by high freezing point: Coconut oil itself has a high freezing point. In the high vacuum environment of the molecular distillation device, if preheating is insufficient or the distillation temperature is set improperly, the viscosity of the material will increase sharply, or even completely solidify, leading to a sharp drop in mass and heat transfer efficiency, interruption of the distillation process, scaling of the equipment, or even failure to operate normally. 2. The risk of decomposition due to the heat sensitivity of diglycerides: Diglycerides and their associated triglycerides are thermally unstable. When the distillation temperature is too high, even under vacuum conditions, significant thermal decomposition, oxidation, or polymerization reactions will occur, generating byproducts such as free fatty acids and monoglycerides. This not only directly leads to a decrease in the yield and purity of the target product, but also affects the color, flavor and stability of the product, seriously damaging the quality of the final product.
[0004] Currently, while there are reports of using molecular distillation to purify diglycerides in existing technologies, these processes often fail to systematically address the core challenge of coconut oil diglyceride systems: easy solidification at low temperatures and easy decomposition at high temperatures. Existing single-stage or two-stage distillation methods often suffer from insufficient separation, making it difficult to efficiently enrich the target product and ensure its purity while removing light impurities. Even with multi-stage distillation, the lack of a precise and coordinated temperature control sequence prevents the resolution of the aforementioned core problem.
[0005] Therefore, there is an urgent need in this field for a molecular distillation purification method specifically for coconut oil diglyceride systems to solve the above-mentioned technical problems. Summary of the Invention
[0006] Therefore, the technical problem to be solved by the present invention is to provide a method for preparing high-purity coconut oil diglycerides based on multi-stage distillation and its application. The present invention uses coconut oil containing diglycerides as raw material, adopts multi-stage molecular distillation method and optimizes its process conditions, and the product obtained is not only of high purity, but also has a significantly improved yield.
[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solutions:
[0008] In a first aspect, the present invention provides a method for preparing high-purity coconut oil diglycerides based on multi-stage distillation, comprising the following steps:
[0009] Coconut oil raw material containing diglycerides is subjected to primary molecular distillation under a certain vacuum and at a temperature not lower than the freezing point of coconut oil to obtain the primary heavy phase;
[0010] The above primary heavy phase is subjected to secondary molecular distillation under a certain vacuum to obtain a secondary light phase. The temperature of the secondary molecular distillation is not lower than the evaporation temperature of diglyceride and not higher than its decomposition temperature.
[0011] The above-mentioned secondary light phase is subjected to tertiary molecular distillation under a certain vacuum and at a temperature not lower than the freezing point of coconut oil to obtain high-purity coconut oil diglyceride.
[0012] Preferably, the vacuum degree during the primary molecular distillation is 0.5-2 Pa, and the temperature is 20-140℃.
[0013] Preferably, the vacuum degree during the secondary molecular distillation is 0.5-2 Pa and the temperature is 150-180℃.
[0014] Preferably, the vacuum degree of the three-stage molecular distillation is 0.5-2 Pa and the temperature is 120-140℃.
[0015] Preferably, the vacuum degree during the first-stage molecular distillation, second-stage molecular distillation, and third-stage molecular distillation is 0.8-1.2 Pa.
[0016] Preferably, the temperature during the primary molecular distillation is 125-135°C.
[0017] Preferably, the temperature during the secondary molecular distillation is 160-170°C.
[0018] Preferably, the temperature during the tertiary molecular distillation is 125-135°C.
[0019] Preferably, the coconut oil raw material containing diglycerides is prepared by chemical transesterification or enzymatic transesterification, and its initial diglyceride content is 40-50 wt%.
[0020] Secondly, the present invention provides the application of the high-purity coconut oil diglyceride, which can be used to prepare functional oils, health products or pharmaceuticals.
[0021] Compared with the prior art, the technical solution of the present invention has at least the following advantages:
[0022] This invention provides a method for preparing coconut oil diglycerides based on multi-stage distillation. The method employs multi-stage molecular distillation and uses a temperature gradient of low temperature-high temperature-low temperature to effectively avoid the freezing point of coconut oil and the thermal decomposition point of diglycerides, thus solving the problem that is difficult to balance in the prior art. The resulting product has the advantages of both high yield and high purity.
[0023] This invention controls the temperature of primary molecular distillation to be no lower than the freezing point of coconut oil, ensuring that the coconut oil does not solidify, thereby effectively distilling out light components such as free fatty acids and monoglycerides from the raw material, while maintaining the fluidity of the material, laying the foundation for subsequent efficient distillation.
[0024] This invention controls the temperature of the secondary molecular distillation to be no lower than the evaporation temperature of diglycerides and no higher than the decomposition temperature of diglycerides, thereby achieving efficient distillation and enrichment of the main diglyceride component without affecting product loss.
[0025] This invention controls the temperature of the three-stage molecular distillation to be no lower than the solidification temperature of coconut oil, refining the enriched diglyceride fraction and removing trace amounts of light impurities at a lower temperature, thereby stabilizing the purity of the product to over 90% while avoiding product decomposition caused by prolonged high-temperature operation, thus improving the product yield.
[0026] The multi-stage molecular distillation process of this invention works synergistically to form an organic whole, achieving efficient and high-precision separation within a narrow temperature range and under a fixed vacuum. It can stably obtain products with a diglyceride purity of over 90%, and due to effective control of high-temperature heating time and temperature, the product has a light color, few byproducts, and high quality. The entire process is clear, parameter control is simple, and complex vacuum adjustments are avoided. Energy consumption and equipment costs are relatively low, making it very suitable for industrial-scale production. Attached Figure Description
[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0028] Figure 1A schematic diagram of the process for preparing high-purity coconut oil diglyceride oil. Detailed Implementation
[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0030] To address the problems identified in the background section, this invention provides the following technical solution, the specific process of which is as follows: Figure 1 As shown.
[0031] A method for preparing high-purity coconut oil diglycerides based on multi-stage distillation includes the following steps:
[0032] S1: Coconut oil raw material containing diglycerides is subjected to primary molecular distillation under a certain vacuum degree and at a temperature not lower than the freezing point of coconut oil to obtain the primary heavy phase;
[0033] S2: The above primary heavy phase is subjected to secondary molecular distillation under a certain vacuum to obtain a secondary light phase. The temperature of the secondary molecular distillation is not lower than the evaporation temperature of diglyceride and not higher than its decomposition temperature.
[0034] S3: The above-mentioned secondary light phase is subjected to tertiary molecular distillation under a certain vacuum and at a temperature not lower than the freezing point of coconut oil to obtain high-purity coconut oil diglycerides.
[0035] This invention solves the solidification and decomposition problems in the purification process of coconut oil diglycerides by using three-stage molecular distillation and setting a three-stage temperature gradient of low temperature-high temperature-low temperature, combined with a specific high vacuum degree, thereby obtaining coconut oil diglycerides with high yield and high purity.
[0036] Regarding step S1:
[0037] In some embodiments of the present invention, the temperature of the primary molecular distillation is 120-140°C, and the vacuum degree is 0.5-2 Pa. These conditions ensure that the coconut oil does not solidify and that light components such as free fatty acids and monoglycerides in the raw material are effectively distilled out, while maintaining the fluidity of the material, thus laying the foundation for subsequent efficient distillation.
[0038] Furthermore, the temperature of the primary molecular distillation is 125-135°C.
[0039] Regarding step S2:
[0040] In some embodiments of the present invention, the temperature of the secondary molecular distillation is 150-180°C, and the vacuum degree is 0.5-2 Pa. Under these conditions, the temperature is raised to the effective evaporation window of diglycerides, but strictly controlled below the critical temperature for thermal decomposition, thereby achieving efficient distillation and enrichment of the main diglyceride fraction.
[0041] Furthermore, the temperature of the secondary molecular distillation is 160-170°C.
[0042] Regarding step S3:
[0043] In some embodiments of the present invention, the temperature of the tertiary molecular distillation is 120-140°C, and the vacuum degree is 0.5-2 Pa. Under the above conditions, the enriched diglyceride fraction is further purified to remove trace light impurities at a lower temperature, thereby stabilizing the purity to over 90% while avoiding product decomposition caused by prolonged high-temperature operation.
[0044] Furthermore, the temperature of the tertiary molecular distillation is 125-135℃.
[0045] The aforementioned primary, secondary, and tertiary molecular distillations are all performed under high vacuum. Furthermore, the vacuum level for these processes is preferably 0.8-1.2 Pa, which simplifies equipment control and operation.
[0046] The high-purity coconut oil diglyceride product obtained by this invention has a diglyceride purity of ≥90%, and the above product can be used to prepare functional oils, health products or pharmaceuticals.
[0047] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.
[0048] The coconut oil raw materials containing diglycerides in the following examples were all prepared using the following general steps:
[0049] Using Novozym 435 enzyme as a catalyst, with a molar ratio of coconut oil to monoglyceride of 1:2.5, a reaction time of 9.18 h, a reaction temperature of 65 °C, and an enzyme addition of 3.60% of the total mass of coconut oil and monoglyceride, diglyceride oil was prepared, in which the proportion of diglyceride was 54.65 wt%.
[0050] Example 1
[0051] A method for preparing high-purity coconut oil diglycerides based on multi-stage molecular distillation includes the following steps:
[0052] (1) The coconut oil raw material containing diglycerides was subjected to primary molecular distillation at a temperature of 130℃ and a vacuum of 1Pa to distill off the light components and obtain the primary heavy phase.
[0053] (2) The above primary heavy phase was subjected to secondary molecular distillation at a temperature of 165℃ and a vacuum of 1Pa to distill off and collect the fraction rich in diglycerides, thus obtaining the secondary light phase;
[0054] (3) The above-mentioned secondary light phase is subjected to tertiary molecular distillation at a temperature of 130℃ and a vacuum of 1Pa to distill off the residual light components and collect the tertiary heavy phase, which is high-purity coconut oil diglyceride.
[0055] Example 2
[0056] The difference between this embodiment and embodiment 1 is that in step (2), the temperature of the secondary molecular distillation is 150°C and the vacuum degree is 1 Pa, while the other operations are the same as in embodiment 2.
[0057] Example 3
[0058] The difference between this embodiment and embodiment 1 is that in step (2), the temperature of the secondary molecular distillation is 175°C and the vacuum degree is 1 Pa, while the other operations are the same as in embodiment 1.
[0059] Example 4
[0060] The difference between this embodiment and Embodiment 1 is that in step (1), the temperature of the first-stage molecular distillation is 125°C and the vacuum degree is 1Pa; the temperature of the third-stage molecular distillation is 135°C and the vacuum degree is 1Pa, and other operations are the same as in Embodiment 1.
[0061] Comparative Example 1
[0062] The preparation method of coconut oil diglyceride in this comparative example is as follows:
[0063] Coconut oil raw material containing diglycerides was directly subjected to single-stage molecular distillation at a temperature of 165℃ and a vacuum of 1Pa, and the heavy phase was collected as the final product.
[0064] Comparative Example 2
[0065] The difference between this comparative example and Example 1 is that step (3) is not included, while the other operations are the same as in Example 1.
[0066] Comparative Example 3
[0067] The difference between this comparative example and Example 1 is that in step (2), the temperature of the secondary molecular distillation is 190°C and the vacuum degree is 1 Pa, while the other operations are the same as in Example 1.
[0068] Comparative Example 4
[0069] The difference between this comparative example and Example 1 is that in step (1), the temperature of the primary molecular distillation is 110°C and the vacuum degree is 1 Pa, while other operations are the same as in Example 1. It was found that during the primary molecular distillation process, the material solidified, the distillation process could not continue, and no effective product was obtained.
[0070] The products of Examples 1-4 and Comparative Examples 1-4 were analyzed, and the results are shown in Table 1.
[0071] Table 1
[0072] Diglyceride content (%) Free fatty acid content (%) Example 1 93.8 0.4 Example 2 90.5 0.4 Example 3 90.8 0.5 Example 4 91.5 0.4 Comparative Example 1 68 4.5 Comparative Example 2 82.3 0.7 Comparative Example 3 85.7 4.2 Comparative Example 4 —— ——
[0073] As can be seen from the test results in Table 1, compared with the comparative example, the three-stage molecular distillation method used in the embodiments of the present invention, with the temperature and vacuum degree of each stage of molecular distillation set within a specific range, yielded diglycerides with a purity higher than 90%. In particular, the products of Examples 1 and 4 achieved high purity while keeping the acid value below 0.5%.
[0074] In Comparative Example 1, a single-stage distillation was performed, and the purity of the product decreased significantly. This is because in a complex mixture system, it is impossible to simultaneously meet multiple objectives such as fluidity, effective separation, and prevention of decomposition through a single distillation. It is also impossible to take into account the different temperature requirements for removing light components and distilling the target product. The acid value of the product also increased significantly.
[0075] Comparative Example 2 only underwent primary and secondary molecular distillation without further purification, and the purity of the product decreased to some extent, indicating that tertiary molecular distillation is indispensable for preparing high-purity target products.
[0076] In Comparative Example 3, excessively high temperatures during secondary molecular distillation can trigger severe thermal decomposition, leading to a sharp increase in the acid value of the product and its deterioration.
[0077] In Comparative Example 4, the temperature of the primary molecular distillation was too low, below the freezing point of coconut oil. As a result, the material would solidify during the distillation process, making the distillation process impossible.
[0078] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. Based on the embodiments of the present invention, those skilled in the art can make other variations or modifications without creative effort, and all such variations or modifications should fall within the scope of protection of the present invention.
Claims
1. A method for preparing high-purity coconut oil diglycerides based on multi-stage distillation, characterized in that, Includes the following steps: Coconut oil raw material containing diglycerides is subjected to primary molecular distillation under a certain vacuum and at a temperature not lower than the freezing point of coconut oil to obtain the primary heavy phase; The above primary heavy phase is subjected to secondary molecular distillation under a certain vacuum to obtain a secondary light phase. The temperature of the secondary molecular distillation is not lower than the evaporation temperature of diglyceride and not higher than its decomposition temperature. The above-mentioned secondary light phase is subjected to tertiary molecular distillation under a certain vacuum and at a temperature not lower than the freezing point of coconut oil to obtain high-purity coconut oil diglyceride.
2. The method for preparing high-purity coconut oil diglycerides based on multi-stage distillation according to claim 1, characterized in that, The vacuum degree during the primary molecular distillation is 0.5-2 Pa, and the temperature is 20-140℃.
3. The method for preparing high-purity coconut oil diglycerides based on multi-stage distillation according to claim 1, characterized in that, The vacuum degree during the secondary molecular distillation is 0.5-2 Pa, and the temperature is 150-180℃.
4. The method for preparing high-purity coconut oil diglycerides based on multi-stage distillation according to claim 1, characterized in that, The vacuum degree of the tertiary molecular distillation is 0.5-2 Pa, and the temperature is 120-140℃.
5. The method for preparing high-purity coconut oil diglycerides based on multi-stage distillation according to claim 1, characterized in that, The vacuum degree during the first-stage molecular distillation, second-stage molecular distillation, and third-stage molecular distillation is 0.8-1.2 Pa.
6. The method for preparing high-purity coconut oil diglycerides based on multi-stage distillation according to claim 1, characterized in that, The temperature during the primary molecular distillation is 125-135℃.
7. The method for preparing high-purity coconut oil diglycerides based on multi-stage distillation according to claim 1, characterized in that, The temperature during the secondary molecular distillation is 160-170℃.
8. The method for preparing high-purity coconut oil diglycerides based on multi-stage distillation according to claim 1, characterized in that, The temperature during the tertiary molecular distillation is 125-135℃.
9. The method for preparing high-purity coconut oil diglycerides based on multi-stage distillation according to claim 1, characterized in that, The coconut oil raw material containing diglycerides is prepared by chemical transesterification or enzymatic transesterification, and its initial diglyceride content is 40-50 wt%.
10. The use of high-purity coconut oil diglyceride prepared by the method according to any one of claims 1-9 in the preparation of functional oils, health products or pharmaceuticals.