Preparation method of jasmine supercritical extract with high yield and high aroma retention

Abstract

The invention relates to the technical field of plant extraction, in particular to a preparation method of a high-yield and high-aroma-retention jasmine flower supercritical extract. The preparation method comprises the following steps: S1, freeze-drying fresh jasmine flowers to obtain freeze-dried petals; s2, melting ice crystals condensed in a cold trap of the freeze dryer at normal temperature, and recovering to obtain freeze-dried water of the fresh jasmine flowers; s3, performing nanofiltration purification on the fresh jasmine flower freeze-dried water to obtain a jasmine flower extracting solution A; s4, the freeze-dried petals are put into a supercritical extraction kettle to be subjected to supercritical extraction, and jasmine flower extracting solutions B and C are obtained; s5, mixing the prepared jasmine flower extracting solution A, jasmine flower extracting solution B and jasmine flower extracting solution C in proportion to obtain a jasmine flower extract; and S6, carrying out microfiltration sterilization treatment to obtain the jasmine flower supercritical extract. Freeze drying, supercritical extraction and membrane separation technologies are adopted, aroma components in the jasmine flower extract are effectively reserved, and aroma loss and variation caused by high temperature are avoided.

Description

Technical Field

[0001] This invention relates to the field of plant extraction technology, specifically to a method for preparing a high-yield and highly aromatic supercritical jasmine extract. Background Technology

[0002] Jasmine, belonging to the genus Jasminum in the Oleaceae family, is widely cultivated in Guangxi, Fujian, Yunnan, Sichuan, and other regions. Its unique fragrance has secured it an important place in the food and cosmetics industries, especially with the increasing demand for it as a natural fragrance and skincare ingredient. Natural jasmine extract, with its pure and natural properties, satisfies consumers' preference for natural ingredients and has become a highly sought-after product in the market.

[0003] Currently, the production of jasmine extract mainly relies on traditional processes such as solvent extraction and high-temperature concentration. However, these processes have significant shortcomings, becoming a key bottleneck restricting product quality. Existing research, such as the study on extraction conditions of dried jasmine flower extract published by Bi Xiaodan et al. in 2014, shows that while conventional solvents like ethanol and ethyl acetate can dissolve some active ingredients during solvent extraction, they lack selectivity for low-boiling-point, volatile aroma compounds in jasmine (such as linalool and linalyl acetate). Furthermore, subsequent solvent separation can easily lead to the loss of aroma components along with the solvent. In their paper "Research on Extraction Process of Jasmine Volatile Oil," Wang Dong et al. found that the high-temperature concentration stage (usually at temperatures >60℃) further damages heat-sensitive aromatic components and functional substances, weakening the original aroma characteristics of the extract and even producing off-flavors such as burnt taste, seriously affecting the flavor and quality of the product. Furthermore, traditional processes also pose a risk of solvent residue: even after multiple desolventizing steps, trace amounts of solvent may remain, which not only fails to meet food and cosmetic safety standards but also masks the fresh aroma of jasmine itself. Simultaneously, impurities such as polysaccharides and proteins are easily mixed into the extract, leading to decreased product stability and problems such as layering and discoloration during storage, increasing the difficulty of application.

[0004] Therefore, an innovative production process is urgently needed to reduce the loss of aroma components and better preserve the original flavor of jasmine. Such a method should improve the purity and stability of the extract, so that the final product not only has a fresh and long-lasting aroma, but also exhibits greater stability during storage and application. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of existing technologies, the present invention aims to provide a method for preparing a high-yield, high-aroma-retention supercritical jasmine extract. This method employs freeze-drying, supercritical extraction, and membrane separation technologies. Low-temperature freeze-drying effectively reduces the loss and deterioration of aroma and active ingredients in jasmine flowers. Supercritical extraction efficiently extracts aromatic components from jasmine flowers under low temperature and high pressure conditions. Membrane separation achieves low-temperature purification and concentration of the extract, while simultaneously sterilizing it, further improving the purity and stability of the extract. The resulting jasmine extract not only has a fresh and long-lasting aroma but is also easy to store and use. Furthermore, its preparation is simple, suitable for industrial production, and has broad application prospects.

[0006] The objective of this invention is achieved through the following technical solution: This invention provides a method for preparing a high-yield and highly aromatic supercritical jasmine extract, comprising the following steps: S1. After removing the calyx and receptacle from fresh jasmine flowers, freeze the separated petals at a low temperature of -40℃ to -80℃ for more than 30 minutes, and then place them in a freeze dryer for freeze drying until the petals are completely dry to obtain freeze-dried petals. S2. After melting the ice crystals that condensed in the cold trap of the freeze dryer in step S1 at room temperature, the ice crystals are recovered to obtain freeze-dried water with jasmine flower fragrance. S3. The freeze-dried jasmine flower water obtained in step S1 is purified by nanofiltration. The extract is filtered, purified and concentrated using a 500Da~1000Da polyvinyl alcohol nanofiltration membrane to obtain jasmine flower extract A. S4. After pulverizing the freeze-dried petals obtained in step S1, add 10-40% by mass of 95% ethanol and mix evenly. Then, put the mixture into a supercritical extraction vessel for supercritical extraction. The supercritical fluid containing the active components of jasmine is then purified under different fractionation conditions in separation vessel I and separation vessel II to obtain different aroma-enriched components. Jasmine extract B is obtained in separation vessel I, and jasmine extract C is obtained in separation vessel II. S5. The prepared jasmine flower extract A, jasmine flower extract B and jasmine flower extract C are mixed in a mass ratio of 1-80:1-50:1-50 to obtain jasmine flower extract. S6. Sterilization: After recovering the obtained jasmine extract, microfiltration sterilization treatment is performed using a 0.2-0.24μm polyvinylidene fluoride membrane. The sterilized permeate obtained after filtration is aseptically filled to obtain jasmine supercritical extract.

[0007] In this invention, the preparation method of high-yield and high-aroma-retention jasmine supercritical extract employs a combination of freeze-drying, supercritical extraction, and multi-stage membrane separation technologies. The entire process is performed at low temperatures, and aroma components resulting from phase changes during freeze-drying are retained through the recovery of the condensate. Supercritical extraction, using carbon dioxide as a solvent in a low-temperature, high-pressure environment, preserves heat-sensitive substances and prevents oxidation. Simultaneously, this process combines extraction and separation; the supercritical solvent CO2 is easily separated, resulting in no residual solvent and high extraction efficiency. In the membrane filtration technology for post-freeze-drying water recovery, nanofiltration, typically conducted at low or room temperature, prevents the aroma components in the jasmine extract from evaporating and allows for effective purification. Furthermore, nanofiltration membranes remove macromolecular and polymeric impurities from the freeze-dried water, thus effectively preserving the aroma substances in the jasmine extract. Moreover, membrane filtration technology offers significant advantages over high-temperature sterilization in protecting product quality and improving efficiency. Sterilization at low temperatures effectively protects the activity of heat-sensitive substances and avoids high-temperature damage. Meanwhile, membrane filtration is simple to operate, energy-efficient, and avoids oxidation reactions, maintaining product stability. Furthermore, the equipment can be used sustainably, reducing long-term operating costs. This novel supercritical extraction technology for natural jasmine extract has broad application prospects and can be used in high-end products in the food additive, flavoring, and cosmetic industries. It provides an efficient way to enhance the natural aroma and quality of products, overcoming the challenges of traditional processes involving phase transitions and high temperatures during extraction, concentration, or sterilization. Phase transitions lead to the loss of volatile aroma components, while higher temperatures reduce the content of volatile components such as 3-hexen-1-ol and linalool, and increase the content of benzyl alcohol. High-temperature sterilization disrupts the balance of characteristic aroma components in the extract, ultimately leading to aroma variation.

[0008] Furthermore, in step S1, the processing temperature inside the freeze dryer is -60℃ to -80℃, and the pressure is 2Pa to 40Pa.

[0009] Furthermore, in step S2, the vacuoles of jasmine cell tissue contain volatile substances with the characteristic aroma of jasmine. During the freeze-drying process in step S1, the volatile substances will sublimate after the cytoplasmic water sublimates, and then condense into ice crystals in the cold trap of the freeze dryer.

[0010] Furthermore, in step S3, the filtration pressure is 0.4MPa to 0.8MPa, and the temperature is 10℃ to 30℃.

[0011] Furthermore, in step S4, the extraction temperature is 20℃~45℃, the extraction pressure is 10Mpa~40Mpa, and the extraction time is 10~150min.

[0012] Furthermore, in step S4, the temperature inside the separation vessel I is 30℃~45℃, and the pressure is 2Mpa~10Mpa.

[0013] Furthermore, in step S6, the filtration pressure is 0.05 MPa to 0.2 MPa, and the filtration temperature is 10°C to 30°C.

[0014] The beneficial effects of this invention are as follows: 1. The present invention employs a combination of freeze-drying technology, supercritical extraction technology, and multi-stage membrane separation technology. The entire process is carried out at low temperatures. The aroma components caused by phase change during freeze-drying are also retained through the recovery of condensate. The supercritical extraction technology uses carbon dioxide as a solvent in a low-temperature and high-pressure environment, which preserves heat-sensitive substances and makes them less prone to oxidation. At the same time, this process combines extraction and separation. The supercritical solvent CO2 is easy to separate, the extract has no residual solvent, and the extraction efficiency is high.

[0015] 2. In membrane filtration technology for post-freeze-dried water recovery, nanofiltration, typically conducted at low or ambient temperatures, minimizes the volatilization of aroma components in jasmine extract and allows for effective purification. Simultaneously, nanofiltration membranes remove macromolecular and polymeric impurities from the freeze-dried water, thus effectively preserving the aroma compounds in the jasmine extract.

[0016] 3. Compared with high-temperature sterilization, membrane filtration technology has significant advantages in protecting product quality and improving efficiency. Membrane filtration sterilizes at low temperatures, effectively protecting the activity of heat-sensitive substances and preventing damage from high temperatures. At the same time, membrane filtration is simple to operate, energy-efficient, and avoids oxidation reactions, maintaining product stability. Furthermore, the equipment can be used sustainably, reducing long-term operating costs. Attached Figure Description

[0017] Figure 1 This is a comparison chart of GC-MS analysis of traditional jasmine extract and supercritical jasmine extract.

[0018] Figure 2 This is a comparison chart of GC-MS analysis of freeze-dried jasmine water and supercritical jasmine extract.

[0019] Figure 3 This is a sensory evaluation data chart. Detailed Implementation

[0020] To facilitate understanding by those skilled in the art, the following description is provided in conjunction with embodiments and appendices. Figure 1-3 The present invention will be further described below, and the content mentioned in the embodiments is not intended to limit the present invention.

[0021] In some embodiments of the present invention, the present invention provides a method for preparing a high-yield and highly aromatic supercritical jasmine extract, comprising the following steps: S1. After removing the calyx and receptacle from fresh jasmine flowers, freeze the separated petals at a low temperature of -40℃ to -80℃ for more than 30 minutes, and then place them in a freeze dryer for freeze drying until the petals are completely dry to obtain freeze-dried petals. S2. After melting the ice crystals that condensed in the cold trap of the freeze dryer in step S1 at room temperature, the ice crystals are recovered to obtain freeze-dried water with jasmine flower fragrance. S3. The freeze-dried jasmine flower water obtained in step S1 is purified by nanofiltration. The extract is filtered, purified and concentrated using a 500Da~1000Da polyvinyl alcohol nanofiltration membrane to obtain jasmine flower extract A. S4. After pulverizing the freeze-dried petals obtained in step S1, add 10-40% by mass of 95% ethanol and mix evenly. Then, put the mixture into a supercritical extraction vessel for supercritical extraction. The supercritical fluid containing the active components of jasmine is then purified under different fractionation conditions in separation vessel I and separation vessel II to obtain different aroma-enriched components. Jasmine extract B is obtained in separation vessel I, and jasmine extract C is obtained in separation vessel II. S5. The prepared jasmine flower extract A, jasmine flower extract B and jasmine flower extract C are mixed in a mass ratio of 1-80:1-50:1-50 to obtain jasmine flower extract. S6. Sterilization: After recovering the obtained jasmine extract, microfiltration sterilization treatment is performed using a 0.2-0.24μm polyvinylidene fluoride membrane. The sterilized permeate obtained after filtration is aseptically filled to obtain jasmine supercritical extract.

[0022] Furthermore, in step S1, the processing temperature inside the freeze dryer is -60℃ to -80℃, and the pressure is 2Pa to 40Pa.

[0023] Furthermore, in step S2, the vacuoles of jasmine cell tissue contain volatile substances with the characteristic aroma of jasmine. During the freeze-drying process in step S1, the volatile substances will sublimate after the cytoplasmic water sublimates, and then condense into ice crystals in the cold trap of the freeze dryer.

[0024] Furthermore, in step S3, the filtration pressure is 0.4MPa to 0.8MPa, and the temperature is 10℃ to 30℃.

[0025] Furthermore, in step S4, the extraction temperature is 20℃~45℃, the extraction pressure is 10Mpa~40Mpa, and the extraction time is 10~150min.

[0026] Furthermore, in step S4, the temperature inside the separation vessel I is 30℃~45℃, and the pressure is 2Mpa~10Mpa.

[0027] Furthermore, in step S4, the temperature inside the separation vessel II is 30℃~45℃, and the pressure is 2Mpa~5Mpa.

[0028] Furthermore, in step S6, the filtration pressure is 0.05 MPa to 0.2 MPa, and the filtration temperature is 10°C to 30°C.

[0029] The following are specific embodiments of the present invention: Example 1 This embodiment provides a method for preparing a high-yield and highly aromatic supercritical jasmine extract, comprising the following steps: S1. Take 300g of fresh jasmine flowers, remove the calyx and receptacle to obtain 260g of fresh flowers, freeze the separated petals at a low temperature of -80℃ for more than 30 minutes, and then place them in a freeze dryer for freeze drying until the petals are completely dry to obtain 67g of freeze-dried petals. S2. After melting the ice crystals that condensed in the freeze dryer cold trap in step S1 at room temperature, 185g of freeze-dried jasmine flowers with jasmine fragrance were obtained. S3. The freeze-dried jasmine flower water obtained in step S1 is purified by nanofiltration. The extract is filtered, purified and concentrated using a 500Da polyvinyl alcohol nanofiltration membrane to obtain 100g of jasmine flower extract A. S4. After crushing the freeze-dried petals obtained in step S1, add 20% by mass of 95% ethanol and mix evenly. Then, put the mixture into a supercritical extraction vessel for supercritical extraction. The supercritical fluid containing the active ingredients of jasmine is then purified under different fractionation conditions in separation vessel I and separation vessel II to obtain different aroma-enriched components. Specifically, 5g of jasmine extract B is obtained in separation vessel I, and 24g of jasmine extract C is obtained in separation vessel II. S5. Mix the prepared jasmine flower extract A, jasmine flower extract B and jasmine flower extract C in a mass ratio of 80:5:15 to obtain 100g of jasmine flower extract. S6. Sterilization: After recovering the obtained jasmine extract, it is subjected to microfiltration sterilization treatment using a 0.22μm polyvinylidene fluoride membrane. The sterilized permeate obtained after filtration is aseptically filled to obtain the supercritical jasmine extract.

[0030] Furthermore, in step S1, the processing temperature inside the freeze dryer is -60°C and the pressure is 40Pa.

[0031] Furthermore, in step S2, the vacuoles of jasmine cell tissue contain volatile substances with the characteristic aroma of jasmine. During the freeze-drying process in step S1, the volatile substances will sublimate after the cytoplasmic water sublimates, and then condense into ice crystals in the cold trap of the freeze dryer.

[0032] Furthermore, in step S3, the filtration pressure is 0.5 MPa and the temperature is 10 °C.

[0033] Furthermore, in step S4, the extraction temperature is 30°C, the extraction pressure is 20 MPa, and the extraction time is 90 min.

[0034] Furthermore, in step S4, the temperature inside the separation vessel I is 45°C and the pressure is 10 MPa.

[0035] Furthermore, in step S4, the temperature inside the separation vessel II is 40°C and the pressure is 5 MPa.

[0036] Furthermore, in step S6, the filtration pressure is 0.2 MPa and the filtration temperature is 30°C.

[0037] Experimental verification 1. The contents of jasmine freeze-dried water, traditional jasmine extract, and the supercritical jasmine extract prepared in Example 1 were compared by GC-MS analysis. The results are as follows: Figure 1 , Figure 2 As shown in Table 1.

[0038] Table 1: Comparison of GC-MS content analysis between traditional jasmine flower extract (jasmine flower alcohol extract obtained by traditional solvent extraction and rotary evaporation concentration process) and supercritical fluid extract.

[0039] Results analysis: from Figure 1Table 1 shows that, based on the initial ethanol (solvent) fraction of the supercritical jasmine extract, the supercritical sample had an excessively high ethanol content. After removing the ethanol, the supercritical jasmine extract, compared with the jasmine alcohol extract obtained by traditional solvent extraction and rotary evaporation concentration processes, contained more linalool oxide, α-isopinene, linalool, linalyl acetate, and δ-juniperene. In contrast, the jasmine alcohol extract obtained by traditional solvent extraction (alcohol extraction process) and rotary evaporation concentration contained more β-oplopenone, T-juniperol, methyl hexadecanoate, and ethyl hexadecanoate. This is because jasmine raw materials contain free hexadecanoic acid. In traditional solvent extraction (alcohol extraction process), ethanol is used as the solvent, and under heating conditions, the acid and alcohol undergo an esterification reaction to generate the corresponding methyl or ethyl ester. However, the supercritical process does not involve heating and is surrounded by an inert carbon dioxide gas environment, so this reaction does not occur, thus preserving the original aroma substances in jasmine. Therefore, the volatile light components obtained from supercritical jasmine extract are more abundant and diverse, while the heavy components contain less waxy impurities.

[0040] from Figure 2 It can be seen that among the aroma components contained in the freeze-dried water of fresh jasmine flowers, linalool has the highest content. Linalool, T-juniperol, and methyl palmitate also have high contents. The nanofiltration step arranged in the process design is a key step in the purification and recovery of this aroma component.

[0041] 2. Sensory evaluation Jasmine extract A, jasmine extract B and jasmine extract C were mixed in a mass ratio of 80:5:15 to obtain the ABC compound sample (i.e. the jasmine extract of Example 1). Water, jasmine extract B, and jasmine extract C were mixed in a mass ratio of 80:5:15 to obtain the BC compound supercritical compound. Treatment solution A is jasmine flower extract A prepared in Example 1; The alcohol extract is a jasmine alcohol extract obtained by traditional alcohol extraction and rotary evaporation concentration processes. Eleven perfumers with over five years of experience evaluated the aromas of the above-mentioned ABC blend sample (i.e., the jasmine extract from Example 1), the BC supercritical blend, the A-treated liquid, and the alcohol extract. The results are as follows: Figure 3 As shown.

[0042] according to Figure 3Sensory evaluation data revealed significant differences in aroma quality among different extraction processes. The blended process was generally superior to the single process. The blend of extracts A, B, and C exhibited the best aroma complexity and freshness, demonstrating a balanced and elegant overall quality. The mixture of supercritical extracts B and C showed the strongest aroma intensity and longevity. In contrast, the single process exhibited obvious drawbacks: extract A had a prominent raw, grassy aroma; and traditional alcohol extracts, due to process limitations, had the strongest solvent and stale, oxidized flavor, resulting in poor quality. These results indicate that a reasonable blended process can effectively compensate for the shortcomings of a single method, achieving an optimized balance between aroma intensity, longevity, and natural freshness.

[0043] This invention employs freeze-drying, supercritical fluid extraction, and membrane separation technologies. By using low-temperature processing throughout the entire process, it effectively preserves the aroma components of jasmine extract, avoiding aroma loss and alteration caused by high temperatures. Supercritical fluid extraction is highly efficient and leaves no solvent residue, while membrane filtration achieves purification and sterilization at low temperatures, removing impurities and protecting heat-sensitive substances. Compared to traditional high-temperature sterilization, this process is more efficient and better maintains product quality, showing broad application prospects.

[0044] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing a high-yield and highly aromatic supercritical jasmine extract, characterized in that: Includes the following steps: S1. After removing the calyx and receptacle from fresh jasmine flowers, freeze the separated petals at a low temperature of -40℃ to -80℃ for more than 30 minutes, and then place them in a freeze dryer for freeze drying until the petals are completely dry to obtain freeze-dried petals. S2. After melting the ice crystals that condensed in the cold trap of the freeze dryer in step S1 at room temperature, the ice crystals are recovered to obtain freeze-dried water with jasmine flower fragrance. S3. The freeze-dried jasmine flower water obtained in step S1 is purified by nanofiltration. The extract is filtered, purified and concentrated using a 500Da~1000Da polyvinyl alcohol nanofiltration membrane to obtain jasmine flower extract A. S4. After pulverizing the freeze-dried petals obtained in step S1, add 10-40% by mass of 95% ethanol and mix evenly. Then, put the mixture into a supercritical extraction vessel for supercritical extraction. The supercritical fluid containing the active components of jasmine is then purified under different fractionation conditions in separation vessel I and separation vessel II to obtain different aroma-enriched components. Jasmine extract B is obtained in separation vessel I, and jasmine extract C is obtained in separation vessel II. S5. The prepared jasmine flower extract A, jasmine flower extract B and jasmine flower extract C are mixed in a mass ratio of 1-80:1-50:1-50 to obtain jasmine flower extract. S6. Sterilization: After recovering the obtained jasmine extract, microfiltration sterilization is performed using a 0.2-0.24μm polyvinylidene fluoride membrane. The sterilized permeate obtained after filtration is aseptically filled to obtain the supercritical jasmine extract.

2. The method for preparing the high-yield and aroma-retaining supercritical jasmine extract according to claim 1, characterized in that: In step S1, the processing temperature inside the freeze dryer is -60℃ to -80℃, and the pressure is 2Pa to 40Pa.

3. The method for preparing the high-yield and aroma-retaining supercritical jasmine extract according to claim 1, characterized in that: In step S3, the filtration pressure is 0.4MPa to 0.8MPa and the temperature is 10℃ to 30℃.

4. The method for preparing the high-yield and aroma-retaining supercritical jasmine extract according to claim 1, characterized in that: In step S4, the extraction temperature is 20℃~45℃, the extraction pressure is 10Mpa~40Mpa, and the extraction time is 10~150min.

5. The method for preparing the high-yield and aroma-retaining supercritical jasmine extract according to claim 1, characterized in that: In step S4, the temperature inside the separation vessel I is 30℃~45℃, and the pressure is 2Mpa~10Mpa.

6. The method for preparing the high-yield and aroma-retaining supercritical jasmine extract according to claim 1, characterized in that: In step S4, the temperature inside the separation vessel II is 30℃~45℃, and the pressure is 2Mpa~5Mpa.

7. The method for preparing the high-yield and aroma-retaining supercritical jasmine extract according to claim 1, characterized in that: In step S6, the filtration pressure is 0.05 MPa to 0.2 MPa, and the filtration temperature is 10°C to 30°C.

8. The method for preparing a high-yield and highly aromatic supercritical jasmine extract according to any one of claims 1-7, characterized in that: The obtained supercritical jasmine extract includes high levels of linalool and its oxides, high levels of terpenes, high levels of esters, and esters with jasmine fragrance, wherein the esters with jasmine fragrance include citronellol formate and geraniol formate.

Images