Method for extracting plukenetia volubilis linneo oil based on pulsed electric field and freeze-thaw synergistic demulsification

Abstract

The invention discloses a method for extracting plukenetia volubilis linneo oil based on pulsed electric field and freeze thawing synergistic demulsification. The method comprises the following steps: shelling plukenetia volubilis linneo, crushing the plukenetia volubilis linneo into powder, stirring the powder with deionized water to form a uniform solution, adjusting the pH value to 9.5-11.5, adding alkaline protease, carrying out water bath enzymolysis, standing to room temperature, separating, taking an upper-layer plukenetia volubilis linneo emulsion, carrying out pulsed electric field treatment, freezing and thawing, and centrifuging to obtain yellow and transparent plukenetia volubilis linneo oil. The method comprises the following steps: treating a plukenetia volubilis linneo emulsion formed in an aqueous enzymatic method system in a pulsed electric field static treatment chamber, controlling the electric field intensity at 3.5-8.5 kV / cm, immediately transferring the emulsion treated by the electric field into a refrigerator at-20 DEG C, freezing for 4-8 hours, unfreezing at room temperature, and centrifuging to obtain upper grease. The obtained sacha inchi oil is high in yield and good in nutritional quality, and has the advantages of being short in demulsification period, efficient in oil-water separation and the like.

Description

Technical Field

[0001] The invention relates to a method for extracting sacha inchi oil, in particular to a method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification, belonging to the field of demulsification and oil extraction of food non-thermal processing technology. Background Art

[0002] Reasonable intake of oils and oily foods has become one of the health trends that people are pursuing nowadays. Compared with animal fats, vegetable oils with a high content of unsaturated fatty acids are a more reasonable choice of oils. Among them, sacha inchi oil is rich in unsaturated fatty acids, and its ratio of ω-3 and ω-6 unsaturated fatty acids is about 1:0.75, which is suitable for human absorption and has the effects of anti-cancer, regulating blood lipids, improving immunity and memory. Therefore, the content of unsaturated fatty acids and other nutrients in sacha inchi oil is an important factor in evaluating its quality.

[0003] Since the introduction of sacha inchi into China has only been a short time, strengthening the systematic research and development and utilization of sacha inchi as a new woody oil crop is of great practical significance for promoting the development of the sacha inchi industry and improving the economic value of oil crops. At present, sacha inchi oil is mainly extracted by cold pressing and freeze-thaw method. The oil yield and quality will vary significantly due to different extraction methods. The cold pressing method is more popular because it can better preserve its nutrients. The disadvantage is that the oil yield of sacha inchi oil extracted by cold pressing is low, and the residual oil rate in the cake residue is high.

[0004] The prior art also involves the practice of strengthening cold pressing through strengthening measures such as ultrasound, but the effect needs to be improved. For example, Chinese invention patent application CN107325878A discloses a production method of cold-pressed sacha inchi oil, comprising the following steps: 1) shelling; 2) screening and grading: placing the selected sacha inchi kernels in an ultrasonic container filled with a 35% honey aqueous solution by mass, ultrasonically treating at 30°C with an ultrasonic power of 550-600W for 1 minute, taking out the kernels located in the upper layer, middle layer and lower layer of the ultrasonic container after standing for 6-8 seconds, placing the three types of sacha inchi kernels in an ultrasonic container filled with deionized water at 25°C with an ultrasonic power of 450-500W for 5 minutes, and then placing them in an ultrasonic container filled with magnetized water at 25°C with an ultrasonic power of 600-650W for 5 minutes, and drying at 35°C until the moisture content is less than 10%; 3) crushing and cold pressing: crushing the three types of sacha inchi kernels, drying, oil pressing, mixing and removing impurities. This technology uses ultrasound combined with cold pressing to process the kernels of the walnuts, which significantly improves the oil yield of the kernels and reduces the residual oil rate in the cake residue from 45.5% to 6.9%. However, this technology is complex to operate and has high energy costs. It requires the addition of various types of fibers as auxiliary extrudates and plate and frame filters for impurity removal after multiple ultrasound, vacuum drying, and cold pressing. In particular, this measure does not maintain the nutritional components very well, with the tocopherol content being less than 200 mg / 100 g (see the test data of tocopherol content in Examples 3-5 of this technology), indicating that this technology causes the loss of active ingredients in the oil and reduces the nutritional quality of the oil.

[0005] The main advantages of the freeze-thaw method are that there is no chemical addition, the process is simple, the oil extraction rate is high, and good quality oil can be obtained, but it needs to be repeatedly frozen and thawed, the cycle is long, and the energy cost is high. For example, Chinese invention patent application CN118185696A provides a method for extracting sacha inchi oil by combining water emulsification extraction and freezing demulsification, which includes the following steps: 1) Soaking and crushing: Sacha inchi kernels are immersed in water to soften the tissue fiber structure, and then enter the processing device for crushing; 2) Water emulsification extraction: The crushed sacha inchi kernels are stirred with an appropriate amount of warm water to form an emulsion; 3) Solid-liquid separation: The solid particles and kernel residues in the emulsion are separated by filtration or centrifugation to obtain a mixed liquid; 4) Freeze thaw and high-speed centrifugation: The separated mixed liquid is refrigerated, thawed at room temperature, and then centrifuged in a centrifuge at high speed to obtain pure sacha inchi oil. However, the technical step 2 requires continuous heating and stirring to ensure the continuous temperature of warm water to achieve effective water emulsification extraction, which increases the energy cost and destroys the heat-sensitive active ingredients in sacha inchi oil, thereby affecting the quality of the oil.

[0006] The prior art emphasizes increasing the oil yield of sacha inchi oil and performing enhanced demulsification, which inevitably results in a decrease in the active nutrients of sacha inchi oil, making it difficult to achieve a balance between oil yield and high active nutrients. Summary of the invention

[0007] In view of the shortcomings and defects of the prior art, the purpose of the present invention is to provide a method for extracting sacha inchi oil by pulsed electric field and freeze-thaw synergistic demulsification, which effectively ensures the stability of the nutritional quality of the oil while improving the oil extraction rate, and realizes low-energy consumption, high-efficiency and high-quality sacha inchi oil extraction.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic emulsion demulsification: After the sacha inchi is shelled and crushed into powder, it is stirred with deionized water to form a uniform solution, the pH is adjusted to 9.5-11.5, alkaline protease is added, and after enzymatic hydrolysis in a water bath, the upper sacha inchi emulsion is separated and allowed to stand at room temperature, and then treated with a pulse electric field and then freeze-thawed, and then centrifuged to obtain sacha inchi oil.

[0010] To further achieve the purpose of the present invention, preferably, the sacha inchi fruit is shelled, crushed into powder and then passed through a 60-100 mesh sieve.

[0011] Preferably, the volume ratio of the sacha inchi fruit powder solution obtained by passing through a 60-100 mesh sieve to deionized water is 1:8-1:10.

[0012] Preferably, the stirring with deionized water to achieve uniform stirring is magnetic stirring, and the magnetic stirring speed is 300-500 rpm.

[0013] Preferably, the amount of alkaline protease added is 400-600 U / mL; the heating temperature of the water bath is 40-50° C.; and the water bath enzymolysis time is 1-2 h.

[0014] Preferably, the upper layer of sacha inchi emulsion is collected and refrigerated in a refrigerator at -4°C to 10°C for later use.

[0015] Preferably, the electric field intensity of the pulse electric field treatment is 3.5-8.5 kV / cm, the pulse repetition frequency is 10-20 Hz, the pulse width is 2-10 μs, and the treatment time is 60-120 s.

[0016] More preferably, the electric field strength is 6-7 kV / cm.

[0017] Preferably, the freeze-thaw treatment is to transfer the upper layer of sacha inchi emulsion into a -20°C to -8°C refrigerator for freezing for 5 to 7 hours after being treated with a pulse electric field, and then thaw it at room temperature.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] (1) The prior art cold pressing method extracts sacha inchi oil, and the initial pressing oil yield is low, generally about 40%, and the residual oil rate in the sacha inchi cake is high, resulting in great waste; the present invention finds that for the sacha inchi emulsion formed in the aqueous enzyme method system, pulse electric field treatment can promote the aggregation of oil droplets in the emulsion, and after freeze-thaw treatment, oil crystals are generated between adjacent oil droplets, piercing the oil-water interface film of the emulsion to promote oil release. After the pulse electric field treatment, the small oil droplets dispersed in the emulsion are polarized and aggregated into large oil clusters, creating a beneficial environment for the formation of oil crystals in the subsequent freeze-thaw treatment. The two have the effect of strengthening oil extraction synergistically, increasing the extraction rate of sacha inchi oil to more than 60.7%, greatly reducing the residual oil rate in the cake, and significantly improving the recovery rate of sacha inchi oil.

[0020] (2) Compared with the cold pressing method, freeze-thaw method and enhanced freeze-thaw method in the prior art, the nutritional value of the obtained sacha inchi oil by pulse electric field and freeze-thaw synergistic extraction of the sacha inchi oil is improved, the proportion of unsaturated fatty acids in the oil component determination is increased, the content of functional ingredients such as tocopherol is enriched, and the nutritional quality of the oil is improved.

[0021] (3) The pulse electric field used in the present invention is coordinated with the freeze-thaw demulsification treatment to extract the sacha inchi oil. Compared with the freeze-thaw method which usually requires repeated treatment for 24 hours, the present invention has the advantages of short oil extraction cycle, low energy consumption cost, and high demulsification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the method for extracting sacha inchi oil based on pulsed electric field and freeze-thaw synergistic demulsification.

[0023] Figure 2 It is a graph showing the extraction rate of sacha inchi oil of Examples 1-4 and Comparative Examples 1-3.

[0024] Figure 3 These are laser confocal microscopy images of the sacha inchi fruit emulsions of Examples 1, 3, 4 and Comparative Examples 1 and 3. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention, and the described embodiments are only part of the embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

[0026] Since the existing demulsification and oil extraction technology methods have problems such as long cycle, high energy consumption cost, and difficulty in balancing extraction rate and nutritional quality, the technology of the present invention has outstanding instantaneous high efficiency, energy saving and environmental protection, and its main technical measures are to discover the synergistic effect of pulse electric field and freeze-thaw treatment for demulsification and oil extraction. Specifically, it is a method for demulsification and extraction of sacha inchi oil by combining pulse electric field and freeze-thaw: after the sacha inchi is shelled and crushed into powder, it is stirred into a uniform solution with deionized water, the pH is adjusted to 9.5-11.5, alkaline protease is added, and after enzymatic hydrolysis in a water bath, it is allowed to stand at room temperature and then the upper layer of sacha inchi emulsion is separated and taken, and after pulse electric field treatment, freeze-thaw treatment and centrifugation are performed to obtain sacha inchi oil. The method is based on the fact that protein, as an amphiphilic substance, is the main contributor to the stability of the emulsion. It is easy to adsorb to the oil-water interface for rearrangement. The non-polar lipophilic group is adsorbed on the surface of the oil droplet, and the polar hydrophilic group is combined with water. The internal hydrophobic amino acids are exposed and enter the oil body membrane formed by covalent crosslinking and non-covalent interaction. The electrostatic interaction and steric hindrance generated will inhibit the aggregation of the oil droplets, and the stability of the emulsion is maintained. However, after being treated with a pulsed electric field, the hydrophobic amino acids inside the protein are aggregated and hidden again, the interfacial energy required for the protein to maintain the stability of the emulsion becomes larger, the stability of the emulsion interface film becomes worse, and the problem of the difficulty of internal oil precipitation is improved; and the polarized aggregation of oil droplets under the pulsed electric field promotes the formation of oil crystals in the freeze-thaw treatment, the interface film structure of the emulsion is pierced, and the oil is accelerated to release and the extraction rate is increased. At the same time, the present invention adopts a static parallel plate pulsed electric field treatment, the waveform is a square wave with the most uniform electric field distribution, the interval time between adjacent pulse waves is much greater than the duration, and the material actually receives the pulse treatment time in milliseconds. Therefore, the test found that under the action of the pulsed electric field, the emulsion is in an instantaneous and continuously decaying ambient temperature below 35°C. Compared with other existing technologies (such as microwaves, ultrasound, etc.) in which the material is subjected to continuous minute-level constant temperature treatment, it effectively avoids the destruction of heat-sensitive components in the oil and fat, thereby ensuring the nutritional value of the oil and fat.

[0027] Therefore, the focus of the present invention is to introduce pulse electric field and freeze-thaw to synergize demulsification and oil extraction. As for the specific pulse electric field and freeze-thaw treatment methods, they can be obtained through experimental optimization based on the existing technology and combined with the purpose of the present invention. The present invention is particularly effective in extracting oil from high-oil and high-protein oil plants (such as Sacha Inchi), which helps to promote the application of water enzyme method in the field of grain and oil demulsification and extraction. Under the optimized pulse electric field treatment and freeze-thaw combined treatment conditions, mainly including a pulse electric field intensity of 3.5 to 8.5 kV / cm, a low-frequency pulse repetition frequency of 10 to 20 Hz, a short treatment time of 60 to 120 s, and a freeze-thaw time of 5-7 h, efficient demulsification of Sacha Inchi emulsion can be achieved. The results show that the Sacha Inchi emulsion treated by the present invention is obviously unstable, protein desorption causes the emulsion interface film to be destroyed, the internal oil droplets aggregate and precipitate, and the clear oil yield is significantly improved.

[0028] Figure 1 The flow chart of the method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification. Sacha inchi emulsion is collected under an alkaline protease system, and the emulsion is treated by a pulse electric field and freeze-thaw combination, and then centrifuged to recover the light yellow transparent sacha inchi oil. The present invention uses sacha inchi as a raw material, adds alkaline protease to fully emulsify the sacha inchi, separates and collects the upper layer of sacha inchi emulsion with a pipette, and obtains sacha inchi oil by pulse electric field treatment, freeze-thaw, and centrifugal recovery. The method is convenient, efficient, energy-saving and environmentally friendly, and the obtained sacha inchi oil has a high extraction rate and good nutritional quality.

[0029] Preferably, the method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification of the present invention is specifically implemented as follows:

[0030] (1) Collection of Sacha Inchi Emulsion:

[0031] The sacha inchi fruit is shelled and crushed into powder, and then passed through a 60-100 mesh sieve for later use. The sacha inchi fruit powder is magnetically stirred into a uniform solution with deionized water at a solid-liquid ratio of 1:8-1:10, the pH is adjusted to 9.5-11.5, the temperature is 30-50°C, alkaline protease is added, and the enzyme is magnetically stirred in a water bath for 1-2 hours. After standing and cooling to room temperature, the upper sacha inchi fruit emulsion is separated, collected, and refrigerated in a refrigerator at -4-10°C for later use.

[0032] (2) Pulse electric field demulsification treatment:

[0033] Take an appropriate amount of the sacha inchi emulsion collected in step (1) and transfer it to a pulsed electric field static treatment chamber, and adjust the pulsed electric field parameter conditions as follows: electric field intensity 3.5-8.5 kV / cm, pulse repetition frequency 10-20 Hz, pulse width 2-10 μs, treatment time 60-120 s, to obtain the sacha inchi emulsion after pulsed electric field demulsification treatment.

[0034] (3) Centrifugation to recover Sacha Inchi oil after freeze-thaw:

[0035] The demulsified sacha inchi emulsion in step (2) is quickly transferred to a refrigerator at -20°C to -8°C for freeze-thawing, and then centrifuged to obtain sacha inchi oil.

[0036] The calculation formula of Sacha Inchi Oil Yield (OY): OY = m1 / m2

[0037] Sacha Inchi Oil Extraction Rate (OZ) = Sacha Inchi Oil Yield / Sacha Inchi Emulsion Oil Content

[0038] Where: m1 is the mass of the clear oil of the Sacha Inchi fruit after centrifugal recovery, and m2 is the mass of the Sacha Inchi fruit kernel after crushing.

[0039] Determination of oil content of Sacha Inchi emulsion:

[0040] The oil content of the emulsion was measured by the acid hydrolysis method in accordance with the national standard GB5009.6-2016 Determination of fat in food. The results showed that the oil content of the Sacha Inchi emulsion of the present invention was 30-40%.

[0041] Saponification value: refers to the number of milligrams of sodium hydroxide required to completely saponify 1g of oil, which can reflect the content of saponifiable matter and the molecular weight of fatty acids in the oil, and further evaluate the purity of the oil. The present invention uses the method in GB / T 5534-2008 standard to determine the saponification value of saponaria inchi oil.

[0042] Iodine value: The change in the unsaturation degree of oil is evaluated by the addition reaction of oil and iodine. The present invention adopts the method in GB / T5532-2022 standard to determine the iodine value of sacha inchi oil.

[0043] Fatty acid composition: The fatty acid composition of Sacha Inchi oil was determined by the area normalization method in GB / T5009.168-2016 standard to calculate the content.

[0044] Tocopherol content: The tocopherol content in Sacha Inchi oil was determined by the method in GB / T26635-2011 standard.

[0045] Example 1

[0046] (1) Collection of Sacha Inchi Emulsion:

[0047] The sacha inchi fruit was shelled and crushed into powder, then passed through an 80-mesh sieve, and mixed with deionized water at a volume ratio of 1:10 (magnetic stirring was used to control the rotation speed to 300 rpm), and sodium hydroxide solution was added to adjust the solution pH to 10.5. 500 U / mL alkaline protease was added under magnetic stirring in a 40°C water bath. After enzymolysis for 2 hours, the mixture was allowed to stand and separate into layers. The upper layer of sacha inchi fruit emulsion was collected with a pipette and refrigerated in a -4°C refrigerator for later use.

[0048] (2) Pulse electric field demulsification treatment:

[0049] The sacha inchi emulsion collected in step (1) was transferred into a pulsed electric field. The pulsed electric field action conditions were: electric field intensity of 6 kV / cm, frequency of 15 Hz, pulse width of 10 μs, and demulsification treatment time of 90 s to obtain sacha inchi emulsion treated by a pulsed electric field.

[0050] (3) Centrifugation to recover Sacha Inchi oil after freeze-thaw:

[0051] The demulsified sacha inchi emulsion in step (2) was quickly transferred to a -20°C refrigerator and frozen for 6 hours. After thawing at room temperature, the emulsion was centrifuged at 4000 rpm for 20 minutes. A light yellow transparent sacha inchi oil was observed on the top layer.

[0052] According to the determination method of the yield of sacha inchi, the yield of sacha inchi oil obtained in Example 2 was 20.28%, and the oil extraction rate reached 66.1%.

[0053] Example 2

[0054] (1) Collection of Sacha Inchi Emulsion:

[0055] The sacha inchi fruit was shelled and crushed into powder, then passed through a 60-mesh sieve, and mixed with deionized water at a volume ratio of 1:10 (magnetically stirred at a speed of 500 rpm), and sodium hydroxide solution was added to adjust the solution pH to 10.5. 500 U / mL alkaline protease was added under magnetic stirring in a 40°C water bath, and after enzymatic hydrolysis for 2 hours, the mixture was allowed to stand and separate into layers. The upper layer of sacha inchi fruit emulsion was collected with a pipette and refrigerated in a -4°C refrigerator for later use.

[0056] (2) Pulse electric field demulsification treatment:

[0057] The sacha inchi emulsion collected in step (1) was transferred into a pulsed electric field. The pulsed electric field action conditions were: electric field intensity of 6 kV / cm, frequency of 15 Hz, pulse width of 10 μs, and demulsification treatment time of 90 s to obtain sacha inchi emulsion treated by a pulsed electric field.

[0058] (3) Centrifugation to recover Sacha Inchi oil after freeze-thaw:

[0059] The demulsified sacha inchi emulsion in step (2) was quickly transferred to a -20°C refrigerator and frozen for 8 hours. After thawing at room temperature, the emulsion was centrifuged at 4000 rpm for 20 minutes. A light yellow transparent sacha inchi oil was observed on the top layer.

[0060] According to the determination method of the yield of sacha inchi, the yield of sacha inchi oil obtained in Example 2 was 19.2%, and the oil extraction rate reached 62.6%.

[0061] Example 3

[0062] (1) Collection of Sacha Inchi Emulsion:

[0063] The shelled sacha inchi fruit was crushed into powder, passed through a 100-mesh sieve, and mixed with deionized water at a volume ratio of 1:10 (magnetically stirred at a speed of 400 rpm), and sodium hydroxide solution was added to adjust the solution pH to 10.5. 500 U / mL alkaline protease was added under magnetic stirring in a 40°C water bath. After enzymolysis for 2 hours, the mixture was allowed to stand and separate into layers. The upper layer of sacha inchi fruit emulsion was collected with a pipette and refrigerated in a -4°C refrigerator for later use.

[0064] (2) Pulse electric field demulsification treatment:

[0065] The sacha inchi emulsion collected in step (1) was transferred into a pulsed electric field. The pulsed electric field conditions were as follows: electric field intensity of 8.5 kV / cm, frequency of 15 Hz, pulse width of 10 μs, and demulsification treatment time of 90 s to obtain the sacha inchi emulsion treated by the pulsed electric field.

[0066] (3) Centrifugation to recover Sacha Inchi oil after freeze-thaw:

[0067] The demulsified sacha inchi emulsion in step (2) was quickly transferred to a -20°C refrigerator and frozen for 6 hours. After thawing at room temperature, the emulsion was centrifuged at 4000 rpm for 20 minutes. A light yellow transparent sacha inchi oil was observed on the top layer.

[0068] According to the determination method of the yield of sacha inchi, the yield of sacha inchi oil obtained in Example 2 was 18.8%, and the oil extraction rate reached 61.3%.

[0069] Example 4

[0070] (1) Collection of Sacha Inchi Emulsion:

[0071] The sacha inchi fruit was shelled and crushed into powder, then passed through an 80-mesh sieve, and mixed with deionized water at a volume ratio of 1:10 (magnetic stirring was used to control the rotation speed to 300 rpm), and sodium hydroxide solution was added to adjust the solution pH to 10.5. 500 U / mL alkaline protease was added under magnetic stirring in a 40°C water bath. After enzymolysis for 2 hours, the mixture was allowed to stand and separate into layers. The upper layer of sacha inchi fruit emulsion was collected with a pipette and refrigerated in a -4°C refrigerator for later use.

[0072] (2) Pulse electric field demulsification treatment:

[0073] The sacha inchi emulsion collected in step (1) was transferred into a pulsed electric field. The pulsed electric field action conditions were: electric field intensity of 6 kV / cm, frequency of 15 Hz, pulse width of 6 μs, and demulsification treatment time of 90 s to obtain the sacha inchi emulsion treated by the pulsed electric field.

[0074] (3) Centrifugation to recover Sacha Inchi oil after freeze-thaw:

[0075] The demulsified sacha inchi emulsion in step (2) was quickly transferred to a -20°C refrigerator and frozen for 6 hours. After thawing at room temperature, the emulsion was centrifuged at 4000 rpm for 20 minutes. A light yellow transparent sacha inchi oil was observed on the top layer.

[0076] According to the determination method of the yield of sacha inchi, the yield of sacha inchi oil obtained in Example 2 was 18.6%, and the oil extraction rate reached 60.7%.

[0077] Comparative Example 1

[0078] The specific steps of this comparative example are as follows:

[0079] (1) Collection of Sacha Inchi Emulsion:

[0080] The sacha inchi fruit was shelled and crushed into powder, then passed through an 80-mesh sieve, and mixed with deionized water at a volume ratio of 1:10 (magnetic stirring was used to control the rotation speed to 300 rpm), and sodium hydroxide solution was added to adjust the solution pH to 10.5. 500 U / mL alkaline protease was added under magnetic stirring in a 40°C water bath. After enzymolysis for 2 hours, the mixture was allowed to stand and separate into layers. The upper layer of sacha inchi fruit emulsion was collected with a pipette and refrigerated in a -4°C refrigerator for later use.

[0081] (2) Centrifugation to recover Sacha Inchi oil after freeze-thaw:

[0082] Take an appropriate amount of the sacha inchi emulsion collected in step (1), quickly transfer it to a -20°C refrigerator and freeze it for 6 hours. After thawing at room temperature, centrifuge it at 4000 rpm for 20 minutes. A light yellow transparent sacha inchi oil can be seen on the top layer.

[0083] Comparative Example 1 is a Sacha Inchi fruit emulsion that has not been treated with a pulse electric field. The measured oil yield is 14.7%, and the oil extraction rate is only 47.9%.

[0084] Comparative Example 2

[0085] (1) Collection of Sacha Inchi Emulsion:

[0086] The sacha inchi fruit was shelled and crushed into powder, then passed through an 80-mesh sieve, and mixed with deionized water at a volume ratio of 1:10 (magnetic stirring was used to control the rotation speed to 300 rpm), and sodium hydroxide solution was added to adjust the solution pH to 10.5. 500 U / mL alkaline protease was added under magnetic stirring in a 40°C water bath. After enzymolysis for 2 hours, the mixture was allowed to stand and separate into layers. The upper layer of sacha inchi fruit emulsion was collected with a pipette and refrigerated in a -4°C refrigerator for later use.

[0087] (2) Pulse electric field demulsification treatment:

[0088] The sacha inchi emulsion collected in step (1) was transferred into a pulsed electric field. The pulsed electric field conditions were as follows: electric field intensity of 8.5 kV / cm, frequency of 15 Hz, pulse width of 10 μs, and demulsification treatment time of 90 s to obtain the sacha inchi emulsion treated by the pulsed electric field.

[0089] (3) Centrifugal recovery of Sacha Inchi oil:

[0090] Take an appropriate amount of the sacha inchi emulsion collected in step (2) and quickly transfer it into a centrifuge at 4000 rpm for 20 min. A light yellow transparent sacha inchi oil can be seen on the top layer.

[0091] Comparative Example 2 is a sacha inchi fruit emulsion treated with only a pulse electric field, and the oil yield was measured to be 15.8%, and the oil extraction rate was 51.5%.

[0092] Comparative Example 3

[0093] (1) Collection of Sacha Inchi Emulsion:

[0094] The sacha inchi fruit was shelled and crushed into powder, then passed through an 80-mesh sieve, and mixed with deionized water at a volume ratio of 1:10 (magnetic stirring was used to control the rotation speed to 300 rpm), and sodium hydroxide solution was added to adjust the solution pH to 10.5. 500 U / mL alkaline protease was added under magnetic stirring in a 40°C water bath. After enzymolysis for 2 hours, the mixture was allowed to stand and separate into layers. The upper layer of sacha inchi fruit emulsion was collected with a pipette and refrigerated in a -4°C refrigerator for later use.

[0095] (2) Microwave treatment:

[0096] The sacha inchi emulsion collected in step (1) was transferred into a microwave reaction tube. The microwave treatment conditions were: power of 1200 W and microwave treatment time of 90 s to obtain the sacha inchi emulsion after microwave treatment.

[0097] (3) Centrifugation to recover Sacha Inchi oil after freeze-thaw:

[0098] Take an appropriate amount of the sacha inchi emulsion collected in step (2), quickly transfer it to a -20°C refrigerator and freeze it for 6 hours. After thawing at room temperature, centrifuge it at 4000 rpm for 20 minutes. A light yellow transparent sacha inchi oil can be seen on the top layer.

[0099] Comparative Example 3 is a microwave treatment control, and the oil yield of the Sacha Inchi emulsion was measured to be 16.7%, and the oil extraction rate was 54.3%.

[0100] The physical and chemical indicators and components of the sacha inchi oil extracted from Examples 1-4 and Comparative Examples 1-3 were measured, and the results are shown in Table 1 below.

[0101] Table 1 Analysis of various indicators of Sacha Inchi oil corresponding to Examples 1-4 and Comparative Examples 1-3

[0102]

[0103] Table 1 shows the extraction rate, physical and chemical indicators and component analysis of the sacha inchi oil in each experimental group. As shown in Table 1, the oil extraction rate of comparative examples 1-3 is 45-55%, while the oil extraction rate of the embodiment of the method for extracting sacha inchi oil by pulse electric field and freeze-thaw synergistic demulsification is increased to more than 60%, and the residual oil rate in the sacha inchi cake residue after oil extraction is significantly reduced, indicating that the method of the present invention can significantly improve the oil yield of sacha inchi kernels.

[0104] Meanwhile, it can be seen from Table 1 that, compared with Comparative Example 1 with only freeze-thaw treatment and Comparative Example 2 with only pulse electric field treatment, the extraction of sacha inchi oil by the combination of pulse electric field and freeze-thaw of the present invention has a synergistic effect. In terms of effect, not only the extraction rate is significantly improved to more than 60%, but also the increase in saponification value of the sacha inchi oil extracted in the embodiment indicates that the oil purity is improved, and the increase in iodine value and unsaturated fatty acid content reflects the increase in unsaturation of the oil; in particular, the tocopherol content is increased from 176-189 mg / 100 g to 204-216 mg / 100 g, indicating that the antioxidant active nutrients in sacha inchi kernel oil are significantly increased, and such sacha inchi kernel oil is suitable as an active factor auxiliary additive for anti-aging products.

[0105] Compared with Comparative Example 3 treated with microwaves, the saponification value of the sacha inchi oil extracted in the embodiment of the present invention is increased, the iodine value is increased from 192g / 100g to 198-206g / 100g, the sum of the content of α-linolenic acid and linoleic acid is increased from 74% to 80-84%, and the tocopherol content is increased from 168mg / 100g to 204-216mg / 100g; this indicates that microwave treatment will cause great damage to the active nutrients in the sacha inchi oil.

[0106] In summary, the freeze-thaw, pulsed electric field, and microwave treatment alone cannot simultaneously improve the oil extraction rate and the nutritional quality of the oil. The pulsed electric field and freeze-thaw combination of the present invention can not only improve the oil extraction rate, but also avoid the destruction of the active ingredients in the oil. In particular, the tocopherol content in the sacha inchi oil extracted by the present invention reaches 204-216 mg / 100g, and the iodine value is 198-206 g / 100g, which is significantly higher than the tocopherol content of 187-197 mg / 100g and the iodine value of 186-188 g / 100g extracted by the ultrasonic-assisted cold pressing method in the existing Chinese invention patent application CN107325878A. Therefore, since the sacha inchi oil extracted by this technology is of high purity and nutritious and healthy quality, it is an ideal raw material oil choice for the development of sacha inchi health products and cosmetics, indicating that the quality of sacha inchi oil has been significantly improved.

[0107] Figure 2 The graphs of the extraction rate of sacha inchi oil in various embodiments of extracting sacha inchi oil by using the pulse electric field synergistic freeze-thaw treatment in comparative examples 1-3 are shown. Figure 2 As shown, compared with the comparative example, the extraction rate of sacha inchi oil in the pulse electric field and freeze-thaw combination of the embodiment is significantly improved. Combined with the test results in Table 1 above, the synergistic effect of the pulse electric field and freeze-thaw combination of the present invention is demonstrated from the effect.

[0108] Figure 3The laser confocal microscope images of the specific distribution of oil droplets in the sacha inchi emulsions of Examples 1, 3, 4 and Comparative Examples 1 and 3 (Example 2 and Example 3 are both the intermediate process from initial demulsification to complete demulsification of the emulsion, and the movement and distribution of the oil droplets in the two figures are similar, so Example 3 is selected as a representative display; Comparative Example 1 and Comparative Example 2 are both the initial stage of demulsification, and the distribution and movement of the oil droplets in the emulsion are similar, so Comparative Example 1 is selected). It can be observed from the figure that the red oil phase in Comparative Examples 1 and 2 is mostly small particles with uniform distribution, while the examples after pulse electric field demulsification treatment have significantly larger red oil droplets, among which the number of red aggregated oil droplets in Example 4 increases significantly, and a large surrounding oil droplet chain gradually forms in Example 3, and a giant red oil cluster appears in Example 1. The process from Example 4 to Example 1 is a display of the effective demulsification process, which is consistent with the results of the embodiment 1. Figure 2 The variation trend of oil extraction rate in the emulsion remains consistent, which indicates that pulse electric field treatment can polarize and aggregate oil droplets into a larger oil phase structure, which is beneficial to the release of oil inside the emulsion. The polarization aggregation of oil droplets under the action of pulse electric field promotes the formation of oil crystals in freeze-thaw treatment, the interfacial film structure of the emulsion is pierced, and the oil is accelerated to release and the extraction rate is increased, which proves the synergistic effect of the pulse electric field and freeze-thaw combination of the present invention from a mechanism perspective.

[0109] Moreover, the present invention adopts a static parallel plate pulse electric field treatment, the waveform is a square wave with the most uniform electric field distribution, the interval time between adjacent pulse waves is much longer than the duration, and the material actually receives the pulse treatment time in milliseconds. Therefore, the test found that under the action of the pulse electric field, the emulsion is in an instantaneous and continuously decaying ambient temperature below 35°C. Compared with other existing technologies (such as microwaves, ultrasound, etc.) in which the material is subjected to a continuous minute-level constant temperature treatment, it effectively avoids the destruction of heat-sensitive components in the oil and fat, and ensures the nutritional value of the oil and fat. The advantages of the present invention regarding nutrients in the test results in Table 1 also prove this mechanism.

[0110] Compared with the conventional freeze-thaw method which requires repeated long-term freeze-thaw cycles to achieve effective demulsification, the pulsed electric field treatment of the present invention promotes the formation of oil crystals in the subsequent freeze-thaw process. The effect of the pulsed electric field greatly enhances the freeze-thaw effect. The synergistic treatment of the two greatly shortens the oil extraction process cycle, reduces energy consumption costs, and synergistically enhances the extraction of Sacha Inchi oil, which is not available in other strengthening measures such as ultrasonic treatment and microwave treatment.

Claims

1. A method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification, characterized in that: After the sacha inchi fruit is shelled and crushed into powder, it is stirred with deionized water to form a uniform solution, the pH is adjusted to 9.5-11.5, alkaline protease is added, and after enzymatic hydrolysis in a water bath, the upper sacha inchi fruit emulsion is separated and taken after being allowed to stand at room temperature. After being treated with a pulse electric field, it is freeze-thawed and then centrifuged to obtain the clear yellow and transparent sacha inchi fruit oil.

2. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 1, characterized in that: The sacha inchi fruit is shelled, crushed into powder and then passed through a 60-100 mesh sieve.

3. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 2, characterized in that: The volume ratio of the sacha inchi fruit powder solution obtained by passing through a 60-100 mesh sieve to deionized water is 1:8-1:

10.

4. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 1, characterized in that: The stirring with deionized water to make it uniform is performed by magnetic stirring, and the magnetic stirring speed is 300-500 rpm.

5. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 1, characterized in that: The amount of alkaline protease added is 400-600 U / mL; the heating temperature of the water bath is 40-50° C.; and the water bath enzymolysis time is 1-2 hours.

6. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 1, characterized in that: The upper layer of the sacha inchi emulsion is collected and refrigerated in a refrigerator at -4°C to 10°C for later use.

7. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 1, characterized in that: The electric field intensity of the pulse electric field treatment is 3.5-8.5 kV / cm, the pulse repetition frequency is 10-20 Hz, the pulse width is 2-10 μs, and the treatment time is 60-120 s.

8. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 7, characterized in that: The electric field strength is 6-7 kV / cm.

9. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 1, characterized in that: The freeze-thaw treatment is to treat the upper layer of sacha inchi emulsion with a pulse electric field and then transfer it into a -20°C to -8°C refrigerator for freezing for 5 to 7 hours, and then thaw it at room temperature.

10. The method for extracting sacha inchi oil based on pulse electric field and freeze-thaw synergistic demulsification according to claim 1, characterized in that: The rotation speed of the centrifugal treatment is 2000-4000 rpm, and the centrifugal time is 15-25 minutes.

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