A method for extracting flavor of piper betel leaf and an extraction and concentration device

Abstract

The present application relates to a kind of extraction method and extraction concentration equipment of spearmint flavor, the method uses liquid nitrogen brittle treatment, low-temperature ultrasonic extraction, two-stage ultrafiltration purification, then liquid-liquid extraction by ethyl acetate, the organic phase is concentrated in vacuum;Concentrated solvent vapor generated is introduced into microbubble in separation tank two, and the water phase residual flavor component, concentrated volatile flavor component and ethyl acetate are recovered synchronously.The equipment includes separation tank one, separation tank two, concentration tank and vacuum pump, micro gas plate, temperature control module and the like, and the extraction agent and flavor recovery rate are improved by pressure boosting and low-temperature control.The present application can efficiently recover flavor component, improve the total yield of aroma, reduce solvent loss and flavor loss.

Description

Technical Field

[0001] This invention belongs to the field of pandan leaf extraction technology, and specifically relates to a method for extracting pandan leaf flavor and an extraction and concentration device. Background Technology

[0002] Pandanus leaves (also known as fragrant pandanus) are a tropical plant used in both medicine and food. Rich in volatile flavor components, primarily 2-acetyl-1-pyrrolidone (2AP), supplemented by dozens of pyrazines, aldehydes, alcohols, and esters, they possess a distinctive sweet, glutinous, coconut, and herbal aroma. With an extremely low aroma threshold and a full-bodied flavor profile, they are a high-value natural fragrance ingredient widely used in food processing, daily chemical fragrances, and condiments. The efficient extraction, non-destructive preservation, and precise enrichment of their flavor components are crucial for overcoming industry pain points and achieving large-scale, standardized industrial applications.

[0003] Current methods for extracting pandan leaf flavor mostly employ conventional processes such as direct solvent extraction and steam distillation. However, these methods suffer from several critical technical deficiencies that urgently need to be addressed: after extraction and separation, trace amounts of characteristic flavor substances remaining in the aqueous phase cannot be efficiently recovered, resulting in a low overall yield of the core characteristic component, 2-acetyl-1-pyrroline (2AP). Furthermore, the evaporation of organic solvents during the concentration process can easily carry away flavor substances, leading to irreversible loss of characteristic aroma components. This makes it difficult to achieve targeted enrichment and closed-loop recovery of flavor substances, directly resulting in low raw material utilization, high solvent consumption, and high industrial production costs. Consequently, these methods cannot meet the downstream industry's stable supply demand for high-quality natural flavor raw materials. Summary of the Invention

[0004] This invention provides a method for extracting flavor from pandanus leaves and an extraction and concentration device, which can effectively recover flavor components remaining in the aqueous phase and volatilized during the concentration process, thereby improving the total yield of flavor substances.

[0005] The technical solution adopted in this invention:

[0006] A method for extracting flavor from pandanus leaves includes the following steps:

[0007] S1. Use liquid nitrogen to embrittle the leaves of the Panax notoginseng, scrape off the surface tissue of the leaves, and chop the surface tissue of the leaves.

[0008] S2. Add 40-45% ethanol aqueous solution to the surface tissue of the leaf, with a material-liquid ratio of 1:18-1:20, and extract by ultrasonication at 40-45℃ for 45-50 min at a power of 260-300w to obtain crude extract of Panax notoginseng leaves. After ultrafiltration of the crude extract, the permeate is obtained.

[0009] S3. Mix the ethyl acetate extractant and the permeate in separatory tank one, with the volume ratio of permeate to ethyl acetate being 1:1.0 to 1:1.1.

[0010] S4. After the stratification is completed, transfer the upper organic liquid and the lower aqueous liquid in the separatory tank to the concentration tank and separatory tank 2 respectively.

[0011] S5. Vacuum the concentration tank to reduce pressure and concentrate the liquid, and then transfer it to the bottom of the second separator to be divided into microbubbles of 5-10μm, so as to pressurize the second separator. The maximum internal pressure is 0.15MPa, and the water phase temperature is maintained at 7-10℃ until the concentration is completed.

[0012] S6. After the separation tank 2 is completed, drain the lower aqueous phase and transfer the upper organic phase to the separatory tank 1. Execute steps S1 to S2 to prepare a new permeate. Add the permeate to the separatory tank 1 and add ethyl acetate extractant to make the volume ratio of the permeate to the total volume of ethyl acetate extractant and organic phase 1:1.0 to 1:1.1. Then proceed to step S4.

[0013] Furthermore, after step S1 is completed and before step S2 is executed, the following steps are also included: adding 13-15% sterile water to the surface tissue of the pandanus leaves, adjusting the pH to 5.5-6.5, inoculating with 0.2-0.3% Lactobacillus plantarum, filling the container with nitrogen to replace the air and creating an anaerobic environment, and sealing it, and carrying out incomplete anaerobic fermentation at 30-32℃ for 3.5-4 hours.

[0014] Furthermore, the ultrafiltration in step S2 is performed as follows: the crude extract is purified by a two-stage tandem ultrafiltration membrane gradient purification, with the first stage having a molecular weight cutoff of 25,000 Da and the second stage having a molecular weight cutoff of 15,000 Da, and the permeate is collected and obtained.

[0015] Furthermore, the specific parameters for liquid nitrogen embrittlement in step S1 are as follows: completely immerse fresh pandanus leaves in liquid nitrogen for 50-60 seconds, remove them, and immediately scrape off the leaf surface mesophyll tissue to remove the leaf vein tissue.

[0016] Furthermore, in step S3, the mixing parameters for mixing the ethyl acetate extractant and the permeate in separatory tank 1 are as follows: after adding the ethyl acetate extractant and the permeate to separatory tank 1 in proportion, the mixture is stirred and extracted under closed conditions at a speed of 60-80 r / min for 13-15 min.

[0017] Furthermore, in step S1, the surface tissue of the pandanus leaves is chopped into pieces of 0.7–1 cm.

[0018] An extraction and concentration apparatus includes a separating tank 1, a separating tank 2, and a concentration tank. The separating tank 1 is equipped with a stirring mechanism. The top of the separating tank 1 and the bottom of the separating tank 2 are respectively equipped with a feed valve and a drain valve. The tops of the separating tank 1, the separating tank 2, and the concentration tank are respectively equipped with a suction pump 1, a suction pump 2, and a suction pump 3. The drain ends of the suction pumps 1, 2, and 3 are respectively connected to the interiors of the separating tank 1, the separating tank 2, and the concentration tank. The inlet ends of the suction pumps 1, 2, and 3 are respectively connected to the separating tank 2 via pipes 1, 2, and 3. The bottom of the liquid separator, the bottom of the liquid separator, and the bottom of the concentration tank are provided. Connecting valves 1, 2, and 3 are respectively provided on pipes 1, 2, and 3. A vacuum pump is provided at the top of the concentration tank. The air inlet of the vacuum pump is connected to the concentration tank, and its exhaust end is connected to a micro air plate through an exhaust pipe. The micro air plate is located at the bottom of the liquid separator. A one-way valve for preventing liquid backflow is connected between the exhaust pipe and the micro air plate. Temperature control modules are provided in the liquid separator, the liquid separator, and the concentration tank to regulate the temperature in each tank. A pressure relief valve is provided at the top of the liquid separator.

[0019] Furthermore, the bottom of the concentration tank has a conical structure, with a discharge valve at its lowest point. The top of the concentration tank is equipped with a motor, which is connected to a rotating shaft located inside the concentration tank. The end of the rotating shaft is connected to a scraper that fits and is compatible with the bottom of the concentration tank.

[0020] Furthermore, each of the first and second separators and the concentration tank is equipped with a vent valve at the top, and the concentration tank is equipped with a pressure sensor.

[0021] Furthermore, the temperature control module includes a heat exchange module and a temperature sensor.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention uses Lactobacillus plantarum for mild and incomplete fermentation in a nitrogen-sealed anaerobic environment. This process only loosens the cell wall structure of pandanus leaves to promote the dissolution of flavor substances without destroying or transforming characteristic aroma components. While significantly increasing the total yield of flavor substances, it fully preserves the unique sweet and glutinous aroma and coconut aroma of pandanus leaves, which is different from the conventional fermentation method that changes the flavor.

[0024] 2. The present invention introduces the solvent vapor generated by concentration into the micro-gas plate in the liquid separator II in the form of microbubbles for low-temperature pressurization condensation and re-extraction, which can simultaneously recover residual flavor components in the aqueous phase, concentrated volatile flavor components and ethyl acetate, significantly reducing flavor loss and solvent consumption, and solving the problems of low recovery efficiency and low raw material utilization rate of traditional processes.

[0025] 3. This invention utilizes incomplete anaerobic fermentation to increase the dissolution of flavor substances and uses microbubble closed-loop recovery to reduce flavor and solvent loss. The synergistic effect of the two results in a significant increase in the total yield of flavor substances. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0027] In the diagram: 1. Separating tank 1; 2. Stirring mechanism; 3. Pipe 1; 4. Suction pump 2; 5. Separating tank 2; 6. Vent valve; 7. Pressure relief valve; 8. Drain valve; 9. Exhaust pipe; 10. Check valve; 11. Micro air plate; 12. Concentration sensor; 13. Connecting valve 1; 14. Pipe 2; 15. Connecting valve 2; 16. Exhaust pipe 2; 17. Connecting valve 3; 18. Scraper; 19. Discharge valve; 20. Motor; 21. Concentrating tank; 22. Suction pump 3; 23. Pressure sensor; 24. Pipe 3; 25. Feed valve; 26. Vacuum pump; 27. Temperature sensor; 28. Heat exchange module; 29. ​​Suction pump 1. Detailed Implementation

[0028] To better understand the technical content of this invention, specific embodiments are provided below, and the invention will be further described in conjunction with the accompanying drawings.

[0029] Example 1

[0030] A method for extracting flavor from pandanus leaves includes the following steps:

[0031] S1. Completely immerse fresh pandanus leaves in liquid nitrogen for 60 seconds to crisp them up quickly without damaging the flavor compounds within the cells. Immediately after removing the leaves, scrape off the surface mesophyll tissue and remove the veins. Since the veins have no aroma, removing them can improve the extraction purity. Chop the surface mesophyll tissue into 1cm pieces. Add 15% sterile water to the surface mesophyll tissue and adjust the pH to 6.5. Fill the container with nitrogen to replace the air and create an anaerobic environment. Seal the container and inoculate it with 0.3% Lactobacillus plantarum. Fill the container with nitrogen to replace the air and create an anaerobic environment. Seal the container and carry out incomplete anaerobic fermentation at 32°C for 4 hours.

[0032] S2. Add 45% ethanol aqueous solution to the surface tissue of the leaf, with a material-to-liquid ratio of 1:20. Extract with ultrasound at 45℃ for 50 minutes at a power of 300W. Use the ultrasonic cavitation effect to break the cells and promote the dissolution of flavor substances. Low temperature can avoid the degradation of heat-sensitive aroma to obtain crude extract of pandan leaves. After ultrafiltration of the crude extract, the permeate is obtained.

[0033] Ultrafiltration is performed as follows: the crude extract is purified by a gradient of two-stage tandem ultrafiltration membranes. The first stage has a molecular weight cutoff of 25,000 Da, and the second stage has a molecular weight cutoff of 15,000 Da. The gradient cutoff can remove large molecular impurities such as proteins and polysaccharides, while retaining small molecular flavor substances. The permeate is collected and obtained.

[0034] S3. Add the permeate and ethyl acetate extractant to separatory tank 1 at a volume ratio of 1:1.1, and then extract for 15 minutes with closed stirring at 80 r / min. Control the temperature inside separatory tank 1 to 35℃. Low-speed stirring can fully extract the extract and avoid emulsification caused by high-speed stirring.

[0035] S4. After the stratification is completed, the upper organic liquid and the lower aqueous liquid in the separatory tank 1 are transferred to the concentration tank 21 and the separatory tank 25, respectively.

[0036] S5. Vacuum the concentration tank 21 to reduce pressure and concentrate, control the temperature inside the concentration tank 21 to 35℃ and the vacuum degree to -0.09MPa. The volatilized vapor is transported to the bottom of the separator 5 and divided into 10μm microbubbles to increase the pressure inside the separator 5. The maximum internal pressure is 0.15MPa. The water phase temperature is maintained at 10℃. By using appropriate temperature and pressure, the recovery rate of extractant and flavor substances can be balanced until the concentration is completed. The concentration endpoint is defined as no bubbles are generated in the micro-air plate 11 at the bottom of the separator 5 for more than 8 minutes.

[0037] S6. After the layering is completed in separatory tank 25, drain the lower aqueous phase and transfer the upper organic phase to separatory tank 1. Perform steps S1 to S2 to prepare a new permeate. Add the permeate to separatory tank 1 and add ethyl acetate extractant to make the volume ratio of the permeate to the total volume of ethyl acetate extractant and organic phase 1:1.1. Then proceed to step S4. It should be noted that when the pandan raw material is used up, the upper organic phase can be transferred to separatory tank 1 for temporary storage for future use, or it can be directly discharged to the outside.

[0038] An extraction and concentration apparatus includes a separating tank 1, a separating tank 2 5, and a concentration tank 21. The separating tank 1 is equipped with a stirring mechanism 2. The top of the separating tank 1 and the bottom of the separating tank 2 5 are respectively equipped with a feed valve 25 and a drain valve 8. The tops of the separating tanks 1, 2 5, and 21 are respectively equipped with a suction pump 29, a suction pump 4, and a suction pump 22. The drain ends of the suction pumps 29, 4, and 22 are respectively connected to the interiors of the separating tanks 1, 2 5, and 21. The inlet ends of the suction pumps 29, 4, and 22 are respectively connected to the separating tanks via pipes 3, 14, and 24. The bottom of the second liquid separator 5, the bottom of the first liquid separator 1, and the bottom of the concentration tank 21 are equipped with connecting valves 13, 15, and 17 respectively on pipes 13, 24, and 3. The top of the concentration tank 21 is equipped with a vacuum pump 26. The air inlet of the vacuum pump 26 is connected to the concentration tank 21, and its exhaust end is connected to a micro air plate 11 through an exhaust pipe 9. The micro air plate 11 is located at the bottom of the second liquid separator 5. A one-way valve 10 is connected between the exhaust pipe 9 and the micro air plate 11 to prevent liquid backflow. The first liquid separator 1, the second liquid separator 5, and the concentration tank 21 are all equipped with temperature control modules to regulate the temperature in each tank. The top of the second liquid separator 5 is equipped with a pressure relief valve 7.

[0039] Preferably, the bottom of the concentration tank 21 is a conical structure, with a discharge valve 19 at its lowest point. The top of the concentration tank 21 is equipped with a motor 20, which is connected to a rotating shaft located inside the concentration tank 21. The end of the rotating shaft is connected to a scraper 18 that fits and is suitable for the bottom of the concentration tank 21. During the concentration process, the motor 20 drives the scraper 18 to rotate through the rotating shaft, which improves the concentration efficiency. At the same time, after the discharge valve 19 is opened, it is convenient for the material to be completely discharged after the concentration is completed.

[0040] Preferably, the top of the first liquid separator 1, the second liquid separator 5, and the concentration tank 21 are all equipped with a vent valve 6. The function of the vent valve 6 is to keep it open when liquid is input into or discharged into the tank to avoid abnormal pressure inside the tank. The concentration tank 21 is equipped with a pressure sensor 23, which detects the pressure inside the tank and controls the vacuum pump 26 to work in conjunction with it, so that the pressure inside the concentration tank 21 is stabilized within a preset range.

[0041] Preferably, the temperature control module includes a heat exchange module 28 and a temperature sensor 27. The temperature sensor 27 monitors the liquid temperature in the corresponding tank and transmits it to the control module. The control module then controls the heat exchange module 28. The heat exchange module 28 is used to cool the liquid (when the liquid temperature is high) or heat the liquid (when the liquid temperature is low) so that the liquid is kept within a preset temperature range.

[0042] Working principle of extraction and concentration equipment:

[0043] The permeate and ethyl acetate are fed into separatory tank 1 through feed valve 25. Stirring mechanism 2 is activated to uniformly mix the ethyl acetate extractant and permeate in separatory tank 1. After stratification, control valve 215, vent valve 6 on separatory tank 1, and vent valve 6 on separatory tank 2 are opened, and suction pump 24 is activated to draw the aqueous phase from the lower layer of separatory tank 1 into separatory tank 2 through suction pump 24 and pipe 214. Then, vent valve 6 on separatory tank 2 and the connecting valve 15 are closed. Open valve 2 (15); open control valve 3 (17), open vent valve 6 on concentration tank 21, and start suction pump 3 (22) to draw the remaining organic liquid in separation tank 1 into concentration tank 21 through suction pump 3 (22) and pipe 3 (24). Close all vent valves 6 and control valve 3 (17); start vacuum pump 26 to deliver the volatilized vapor to the micro-air plate 11 at the bottom of separation tank 2 (5), splitting it into microbubbles, thus pressurizing separation tank 2 (5) and enabling ethyl acetate vapor to effectively condense in separation tank 2 (5). In the aqueous phase, flavor compounds volatilized in the concentration tank 21 are mixed with liquid ethyl acetate and recovered, and residual flavor compounds in the aqueous phase are also mixed with liquid ethyl acetate and recovered. When the internal pressure of the separatory tank 25 exceeds 0.15 MPa, the pressure is released using the pressure relief valve 7 until concentration is complete. After the separation is completed in the separatory tank 25, the drain valve 8 and the vent valve 6 on the separatory tank 25 are opened to drain the lower aqueous phase and transfer the upper organic liquid to the separatory tank 1, controlling the liquid absorption. Pump 29 is opened, as are the vent valve 6 and connecting valve 13 on separatory tank 1. The remaining organic liquid in separatory tank 25 is drawn into separatory tank 1 through vent pump 29 and pipe 3. All vent valves 6 and connecting valve 13 are then closed. Optionally, concentration sensors 12 are installed at the inlet end of pipe 24 and the inlet outlet of drain valve 8. When a sudden change in concentration is detected during pipetting or draining, it indicates that the current pipetting or draining is complete, facilitating precise control of pipetting and draining.

[0044] Example 2

[0045] A method for extracting flavor from pandanus leaves includes the following steps:

[0046] S1. Completely immerse fresh pandanus leaves in liquid nitrogen for 50 seconds to crisp them up quickly without damaging the flavor compounds within the cells. Immediately after removing the leaves, scrape off the surface mesophyll tissue and remove the veins. Since the veins have no aroma, removing them can improve the extraction purity. Chop the surface mesophyll tissue into 0.7cm pieces. Add 13% sterile water to the surface mesophyll tissue to adjust the pH to 5.5. Inoculate with 0.2% Lactobacillus plantarum. Fill the container with nitrogen to replace the air and create an anaerobic environment. Seal the container and carry out incomplete anaerobic fermentation at 30°C for 3.5 hours.

[0047] S2. Add 40% ethanol aqueous solution to the surface tissue of the leaf, with a material-to-liquid ratio of 1:18. Extract with ultrasound at 40℃ for 45 minutes at a power of 260W. Use the ultrasonic cavitation effect to break the cells and promote the dissolution of flavor substances. Low temperature can avoid the degradation of heat-sensitive aroma to obtain crude extract of pandan leaves. After ultrafiltration of the crude extract, the permeate is obtained.

[0048] Ultrafiltration is performed as follows: the crude extract is purified by a gradient of two-stage tandem ultrafiltration membranes. The first stage has a molecular weight cutoff of 25,000 Da, and the second stage has a molecular weight cutoff of 15,000 Da. The gradient cutoff can remove large molecular impurities such as proteins and polysaccharides, while retaining small molecular flavor substances. The permeate is collected and obtained.

[0049] S3. After adding the permeate and ethyl acetate extractant to separatory tank 1 at a volume ratio of 1:1.0, extract for 13 minutes with closed stirring at 60 r / min. Control the temperature inside separatory tank 1 to 30℃. Low-speed stirring can fully extract the extract and avoid emulsification caused by high-speed stirring.

[0050] S4. After the stratification is completed, the upper organic liquid and the lower aqueous liquid in the separatory tank 1 are transferred to the concentration tank 21 and the separatory tank 25, respectively.

[0051] S5. Vacuum the concentration tank 21 to reduce pressure and concentrate, control the temperature inside the concentration tank 21 to 30℃ and the vacuum degree to -0.06MPa. The volatilized vapor is transported to the bottom of the separator 5 and divided into 5μm microbubbles, which increases the pressure inside the separator 5. The maximum internal pressure is 0.15MPa. The water phase temperature is maintained at 7℃. By using appropriate temperature and pressure, the recovery rate of extractant and flavor substances can be balanced until the concentration is completed. The concentration endpoint is defined as no bubbles are generated in the micro-air plate 11 at the bottom of the separator 5 for more than 8 minutes.

[0052] S6. After the layering is completed in separatory tank 25, drain the lower aqueous phase and transfer the upper organic phase to separatory tank 1. Execute steps S1 to S2 to prepare a new permeate. Add the permeate to separatory tank 1 and replenish with ethyl acetate extractant to make the volume ratio of the permeate to the total volume of ethyl acetate extractant and organic phase 1:1.0. Then proceed to step S4. It should be noted that when the pandan raw material is used up, the upper organic phase can be transferred to separatory tank 1 for temporary storage for future use, or directly discharged to the outside.

[0053] This embodiment uses the extraction and concentration equipment from Example 1 for extraction and concentration.

[0054] Example 3

[0055] A method for extracting flavor from pandanus leaves includes the following steps:

[0056] S1. Completely immerse fresh pandanus leaves in liquid nitrogen for 55 seconds to crisp them up quickly without damaging the flavor compounds within the cells. Immediately after removing the leaves, scrape off the surface mesophyll tissue and remove the veins. Since the veins have no aroma, removing them can improve the extraction purity. Chop the surface mesophyll tissue of the pandanus leaves into 0.7cm pieces. Add 14% sterile water to the surface mesophyll tissue of the pandanus leaves to adjust the pH to 6. Inoculate with 0.25% Lactobacillus plantarum. Fill the container with nitrogen to replace the air in order to create an anaerobic environment and seal it. Perform incomplete anaerobic fermentation at 31°C for 3.8 hours.

[0057] S2. Add 43% ethanol aqueous solution to the surface tissue of the leaf, with a material-to-liquid ratio of 1:20. Extract by ultrasound at 43℃ for 47 min at a power of 280w. Use the ultrasonic cavitation effect to break the cells and promote the dissolution of flavor substances. Low temperature can avoid the degradation of heat-sensitive aroma to obtain crude extract of pandan leaves. After ultrafiltration of the crude extract, the permeate is obtained.

[0058] Ultrafiltration is performed as follows: the crude extract is purified by a gradient of two-stage tandem ultrafiltration membranes. The first stage has a molecular weight cutoff of 25,000 Da, and the second stage has a molecular weight cutoff of 15,000 Da. The gradient cutoff can remove large molecular impurities such as proteins and polysaccharides, while retaining small molecular flavor substances. The permeate is collected and obtained.

[0059] S3. After adding the permeate and ethyl acetate extractant to the separatory tank 1 at a volume ratio of 1:1.0, the mixture is stirred in a closed container at 70 r / min for 14 min. The temperature inside the separatory tank 1 is controlled at 33℃. Low-speed stirring can ensure sufficient extraction and avoid emulsification caused by high-speed stirring.

[0060] S4. After the stratification is completed, the upper organic liquid and the lower aqueous liquid in the separatory tank 1 are transferred to the concentration tank 21 and the separatory tank 25, respectively.

[0061] S5. Vacuum the concentration tank 21 to reduce pressure and concentrate, control the temperature inside the concentration tank 21 to 33℃ and the vacuum degree to -0.08MPa. The volatilized vapor is transported to the bottom of the separator 25 and divided into 8μm microbubbles, which increases the pressure inside the separator 25. The maximum internal pressure is 0.15MPa. The water phase temperature is maintained at 8℃. By using appropriate temperature and pressure, the recovery rate of extractant and flavor substances can be balanced until the concentration is completed. The concentration endpoint is defined as no bubbles are generated in the micro air plate 11 at the bottom of the separator 25 for more than 8 minutes.

[0062] S6. After the layering is completed in separatory tank 25, drain the lower aqueous phase and transfer the upper organic phase to separatory tank 1. Execute steps S1 to S2 to prepare a new permeate. Add the permeate to separatory tank 1 and replenish with ethyl acetate extractant to make the volume ratio of the permeate to the total volume of ethyl acetate extractant and organic phase 1:1.1. Then proceed to step S4. It should be noted that when the pandan raw material is used up, the upper organic phase can be transferred to separatory tank 1 for temporary storage for future use, or directly discharged to the outside.

[0063] This embodiment uses the extraction and concentration equipment from Example 1 for extraction and concentration.

[0064] Comparative Example 1

[0065] The difference from Example 3 is that the incomplete fermentation step is removed, and the extraction and concentration in this example uses the extraction and concentration equipment of Example 1.

[0066] A method for extracting flavor from pandanus leaves includes the following steps:

[0067] S1. Immerse fresh pandanus leaves completely in liquid nitrogen for 55 seconds to crisp them up quickly without damaging the flavor compounds inside the cells. Immediately after removing the leaves, scrape off the leaf mesophyll tissue from the surface and remove the vein tissue. The veins have no aroma, so removing them can improve the extraction purity. Chop the surface tissue of the pandanus leaves into 0.7cm pieces.

[0068] S2. Add 43% ethanol aqueous solution to the surface tissue of the leaf, with a material-to-liquid ratio of 1:20. Extract by ultrasound at 43℃ for 47 min at a power of 280w. Use the ultrasonic cavitation effect to break the cells and promote the dissolution of flavor substances. Low temperature can avoid the degradation of heat-sensitive aroma to obtain crude extract of pandan leaves. After ultrafiltration of the crude extract, the permeate is obtained.

[0069] Ultrafiltration is performed as follows: the crude extract is purified by a gradient of two-stage tandem ultrafiltration membranes. The first stage has a molecular weight cutoff of 25,000 Da, and the second stage has a molecular weight cutoff of 15,000 Da. The gradient cutoff can remove large molecular impurities such as proteins and polysaccharides, while retaining small molecular flavor substances. The permeate is collected and obtained.

[0070] S3. After adding the permeate and ethyl acetate extractant to the separatory tank 1 at a volume ratio of 1:1.0, the mixture is stirred in a closed container at 70 r / min for 14 min. The temperature inside the separatory tank 1 is controlled at 33℃. Low-speed stirring can ensure sufficient extraction and avoid emulsification caused by high-speed stirring.

[0071] S4. After the stratification is completed, the upper organic liquid and the lower aqueous liquid in the separatory tank 1 are transferred to the concentration tank 21 and the separatory tank 25, respectively.

[0072] S5. Vacuum the concentration tank 21 to reduce pressure and concentrate, control the temperature inside the concentration tank 21 to 33℃ and the vacuum degree to -0.08MPa. The volatilized vapor is transported to the bottom of the separator 25 and divided into 8μm microbubbles, which increases the pressure inside the separator 25. The maximum internal pressure is 0.15MPa. The water phase temperature is maintained at 8℃. By using appropriate temperature and pressure, the recovery rate of extractant and flavor substances can be balanced until the concentration is completed. The concentration endpoint is defined as no bubbles are generated in the micro air plate 11 at the bottom of the separator 25 for more than 8 minutes.

[0073] S6. After the separation is completed in the separatory tank 25, the lower aqueous phase is drained and the upper organic phase is transferred to the separatory tank 1. Steps S1 to S2 are executed to prepare a new permeate. The permeate is added to the separatory tank 1 and ethyl acetate extractant is added so that the volume ratio of the permeate to the total volume of ethyl acetate extractant and organic liquid is 1:1.1. Then, proceed to step S4.

[0074] This embodiment uses the extraction and concentration equipment from Example 1 for extraction and concentration.

[0075] Comparative Example 2

[0076] The difference from Example 3 is that the volatile flavor compounds and ethyl acetate extractant are not recovered:

[0077] A method for extracting flavor from pandanus leaves includes the following steps:

[0078] S1. Completely immerse fresh pandanus leaves in liquid nitrogen for 55 seconds to crisp them up quickly without damaging the flavor compounds within the cells. Immediately after removing the leaves, scrape off the surface mesophyll tissue and remove the veins. Since the veins have no aroma, removing them can improve the extraction purity. Chop the surface mesophyll tissue of the pandanus leaves into 0.7cm pieces. Add 14% sterile water to the surface mesophyll tissue of the pandanus leaves to adjust the pH to 6. Inoculate with 0.25% Lactobacillus plantarum. Fill the container with nitrogen to replace the air in order to create an anaerobic environment and seal it. Perform incomplete anaerobic fermentation at 31°C for 3.8 hours.

[0079] S2. Add 43% ethanol aqueous solution to the surface tissue of the leaf, with a material-to-liquid ratio of 1:20. Extract by ultrasound at 43℃ for 47 min at a power of 280w. Use the ultrasonic cavitation effect to break the cells and promote the dissolution of flavor substances. Low temperature can avoid the degradation of heat-sensitive aroma to obtain crude extract of pandan leaves. After ultrafiltration of the crude extract, the permeate is obtained.

[0080] Ultrafiltration is performed as follows: the crude extract is purified by a gradient of two-stage tandem ultrafiltration membranes. The first stage has a molecular weight cutoff of 25,000 Da, and the second stage has a molecular weight cutoff of 15,000 Da. The gradient cutoff can remove large molecular impurities such as proteins and polysaccharides, while retaining small molecular flavor substances. The permeate is collected and obtained.

[0081] S3. After adding the permeate and ethyl acetate extractant to the separatory tank 1 at a volume ratio of 1:1.0, the mixture is stirred in a closed container at 70 r / min for 14 min. The temperature inside the separatory tank 1 is controlled at 33℃. Low-speed stirring can ensure sufficient extraction and avoid emulsification caused by high-speed stirring.

[0082] S4. After the stratification is completed, the upper organic liquid and the lower aqueous liquid in the separatory tank 1 are transferred to the concentration tank 21 and the separatory tank 25, respectively.

[0083] S5. Vacuum the concentration tank 21 to reduce pressure and concentrate, controlling the temperature inside the concentration tank 21 to 33℃ and the vacuum degree to -0.08MPa. The volatilized vapor is transported to the bottom of the separator 5 and divided into 8μm microbubbles, which increases the pressure inside the separator 5. The maximum internal pressure is 0.15MPa. The water phase temperature is maintained at 8℃. By using appropriate temperature and pressure, the recovery rate of extractant and flavor substances can be balanced until the concentration is completed. The concentration endpoint is defined as no bubbles are generated continuously for more than 8 minutes at the micro-air plate 11 at the bottom of the separator 5. Finally, all the liquid in the separator is discharged.

[0084] This embodiment uses the extraction and concentration equipment from Example 1 for extraction and concentration.

[0085] Test items and test methods

[0086] 1. Total flavor yield

[0087] The total flavor yield was determined by gravimetric method. Total flavor yield = (weight of flavor compounds prepared by a single process / weight of pandan leaf raw material used in a single process) × 100%;

[0088] 2. Subjective evaluation of flavor

[0089] Five professional sensory evaluators were selected to conduct blind evaluations of the flavor compounds prepared in the examples and comparative examples in a uniform, odor-free and interference-free environment.

[0090] 9.0-10.0 points: The characteristic flavor of pandanus is extremely typical, and the flavor is completely consistent without any changes;

[0091] 8.5-8.9 points: Typical pandan flavor characteristics, good flavor consistency, no obvious changes;

[0092] ≤8.4 points: The characteristic flavor is weak or there are changes in flavor or off-flavors.

[0093] Test results

[0094]

[0095] III. Results Analysis

[0096] 1. The total flavor yield of the embodiments was significantly higher than that of the comparative examples. This indicates that the present invention, by introducing a combined process of incomplete anaerobic fermentation of Lactobacillus plantarum and microbubble closed-loop recovery, can effectively loosen the cell wall structure, promote the dissolution of flavor substances, and efficiently recover residual flavor components in the aqueous and gas phases, thereby significantly improving the total flavor yield and achieving significant technological progress compared to existing processes.

[0097] 2. The flavor scores of the embodiments ranged from 9.0 to 9.2, which were highly similar to those of the comparative examples. Both maintained the typical sweet, glutinous, and coconut-like flavor characteristics of pandan leaves, with no significant differences. This indicates that the incomplete anaerobic fermentation process of the present invention is only a pretreatment method to improve the dissolution efficiency of flavor substances, and is not aimed at flavor transformation. It does not alter or destroy the original unique flavor of pandan leaves, and is fundamentally different from the fermentation processes of tea, fruits, and vegetables in the prior art that focus on flavor transformation.

[0098] 3. The total flavor yield of Comparative Example 1 (without incomplete fermentation step) and Comparative Example 2 (without recovery step) was significantly lower than that of the Example. This indicates that the key process features of the present invention are not the superposition of a single technical means, but rather the synergistic effect of improving dissolution efficiency through incomplete anaerobic fermentation and reducing flavor and solvent loss through microbubble closed-loop recovery. Together, they achieve the technical effect of "high yield + complete flavor preservation", overcoming the technical defects of low yield, easy loss of flavor and large solvent loss in traditional extraction processes.

[0099] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for extracting flavor from pandanus leaves, characterized in that, Includes the following steps: S1. Use liquid nitrogen to embrittle the leaves of the Panax notoginseng, scrape off the surface tissue of the leaves, and chop the surface tissue of the leaves. S2. Add 40-45% ethanol aqueous solution to the surface tissue of the leaf, with a material-liquid ratio of 1:18-1:20, and extract by ultrasonication at 40-45℃ for 45-50 min at a power of 260-300w to obtain crude extract of Panax notoginseng leaves. After ultrafiltration of the crude extract, the permeate is obtained. S3. Mix the ethyl acetate extractant and the permeate in separatory tank one, with the volume ratio of permeate to ethyl acetate being 1:1.0 to 1:1.

1. S4. After the stratification is completed, transfer the upper organic liquid and the lower aqueous liquid in the separatory tank to the concentration tank and separatory tank 2 respectively. S5. Vacuum the concentration tank to reduce pressure and concentrate the liquid, and then transfer it to the bottom of the second separator to be divided into microbubbles of 5-10μm, so as to pressurize the second separator. The maximum internal pressure is 0.15MPa, and the water phase temperature is maintained at 7-10℃ until the concentration is completed. S6. After the separation tank 2 is completed, drain the lower aqueous phase and transfer the upper organic phase to the separatory tank 1. Execute steps S1 to S2 to prepare a new permeate. Add the permeate to the separatory tank 1 and add ethyl acetate extractant to make the volume ratio of the permeate to the total volume of ethyl acetate extractant and organic phase 1:1.0 to 1:1.

1. Then proceed to step S4.

2. The method for extracting flavor from pandanus leaves according to claim 1, characterized in that, After step S1 is completed and before step S2 is executed, the following steps are also included: add 13-15% sterile water to the surface tissue of Panax notoginseng leaves, adjust the pH to 5.5-6.5, inoculate with 0.2-0.3% Lactobacillus plantarum, fill the container with nitrogen to replace the air in order to form an anaerobic environment and seal it, and carry out incomplete anaerobic fermentation at 30-32℃ for 3.5-4 hours.

3. The method for extracting flavor from pandanus leaves according to claim 1, characterized in that, The ultrafiltration in step S2 is performed as follows: the crude extract is purified by a gradient of two-stage tandem ultrafiltration membranes, with the first stage having a molecular weight cutoff of 25,000 Da and the second stage having a molecular weight cutoff of 15,000 Da. The permeate is then collected and obtained.

4. The method for extracting flavor from pandanus leaves according to claim 1, characterized in that, The specific parameters for liquid nitrogen embrittlement in step S1 are as follows: completely immerse fresh pandanus leaves in liquid nitrogen for 50-60 seconds, remove them, and immediately scrape off the leaf surface mesophyll tissue to remove the leaf vein tissue.

5. The method for extracting flavor from pandanus leaves according to claim 1, characterized in that, In step S3, the mixing parameters for mixing the ethyl acetate extractant and the permeate in separatory tank 1 are as follows: after adding the ethyl acetate extractant and the permeate to separatory tank 1 in proportion, the mixture is stirred and extracted under closed conditions at a speed of 60-80 r / min for 13-15 min.

6. The method for extracting flavor from pandanus leaves according to claim 1, characterized in that, In step S1, the surface tissue of the pandanus leaves is chopped into pieces of 0.7–1 cm.

7. An extraction and concentration apparatus, characterized in that, The system includes a separating tank 1, a separating tank 2, and a concentrator. The separating tank 1 is equipped with a stirring mechanism. The top of the separating tank 1 and the bottom of the separating tank 2 are respectively equipped with an inlet valve and a drain valve. The tops of the separating tanks 1, 2, and 3 are respectively equipped with a suction pump 1, a suction pump 2, and a suction pump 3. The drain ends of the suction pumps 1, 2, and 3 are respectively connected to the interiors of the separating tanks 1, 2, and 3. The inlet ends of the suction pumps 1, 2, and 3 are respectively connected to the bottom of the separating tank 2 via pipes 1, 2, and 3. The bottom of the separating tank 1 and the bottom of the concentrator are respectively equipped with connecting valve 1, connecting valve 2 and connecting valve 3 on pipe 1, pipe 2 and pipe 3. The top of the concentrator is equipped with a vacuum pump. The air inlet of the vacuum pump is connected to the concentrator, and its exhaust end is connected to a micro air plate through an exhaust pipe. The micro air plate is located at the bottom of the separating tank 2. A one-way valve for preventing liquid backflow is connected between the exhaust pipe and the micro air plate. The separating tank 1, separating tank 2 and the concentrator are all equipped with a temperature control module for adjusting the temperature in each tank. The top of the separating tank 2 is equipped with a pressure relief valve.

8. The extraction and concentration equipment for pandan leaf flavor extraction according to claim 7, characterized in that, The bottom of the concentration tank is a conical structure with a discharge valve at its lowest point. The top of the concentration tank is equipped with a motor, which is connected to a rotating shaft located inside the concentration tank. The end of the rotating shaft is connected to a scraper that fits and is compatible with the bottom of the concentration tank.

9. The extraction and concentration equipment for pandan leaf flavor extraction according to claim 7, characterized in that, Each of the first and second separation tanks and the concentration tank is equipped with a vent valve at the top, and the concentration tank is equipped with a pressure sensor.

10. The extraction and concentration equipment for pandan leaf flavor extraction according to claim 7, characterized in that, The temperature control module includes a heat exchange module and a temperature sensor.

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