A eutectic solvent for enriching oil polyphenol and a preparation method and application thereof

Abstract

The application discloses a kind of for the low eutectic solvent of oil and fat polyphenol enrichment and its preparation method and application, belong to food deep processing and green extraction technical field.The supramolecular low eutectic solvent of the present application uses binary low eutectic solvent as matrix, with cyclodextrin derivative as supramolecular recognition component, and by alkaline aqueous solution and citric acid solution control system hydrophobic state.Using the polarity regulation ability of supramolecular low eutectic solvent, hydrogen bond network effect and host-guest inclusion effect of cyclodextrin derivative, synergistically promote the migration, solubilization and enrichment of trace phenolic compounds in high lipophilic oil and fat matrix, so as to obtain the extraction phase rich in phenolic compounds.The present application uses citric acid instead of strong inorganic acid, with low corrosion, high safety, food system good adaptability, without complex equipment, operating conditions mild and other advantages, suitable for green enrichment of trace active ingredients in edible oil and high value utilization of macadamia nut oil.

Description

Technical Field

[0001] This invention belongs to the field of food deep processing and green extraction technology, specifically relating to a eutectic solvent for enriching oil polyphenols, its preparation method and application. Background Technology

[0002] Macadamia nuts are a woody oilseed crop with high economic value. Their kernels are rich in oil, and cold-pressed macadamia oil is rich in unsaturated fatty acids and various trace active ingredients, possessing high nutritional value and industrial development potential. Phenolic compounds are key trace active substances in vegetable oils, which can delay oil oxidation and deterioration, improve oil quality stability, and enhance the added value of oil products. Therefore, the efficient enrichment of phenolic compounds from macadamia oil is of great significance for improving its functional quality and promoting its high-value utilization.

[0003] However, macadamia nut oil belongs to a high-fat, hydrophobic matrix, containing high levels of nonpolar components such as triglycerides and long-chain fatty acids, while the content of phenolic compounds is low, and some phenolic compounds may exist in trace or bound forms. Due to the significant difference between the strong hydrophobicity of the oil matrix and the medium-to-high polarity of phenolic compounds, the migration and distribution of target phenolic substances between the oil phase and the extraction phase are limited, generally resulting in low extraction yield, poor selectivity, and severe matrix interference. Therefore, how to achieve efficient migration, solubilization, and enrichment of trace phenolic compounds in high-fat oil phase systems is a core technical challenge that urgently needs to be solved in the field of trace active ingredient extraction from edible oils.

[0004] Currently, the extraction of phenolic compounds from vegetable oils mostly uses organic solvent systems such as methanol and ethanol. This method is simple to operate, but it has drawbacks such as high solvent consumption, weak target selectivity, low extraction efficiency, and high environmental safety risks. Although supercritical fluid extraction can reduce the use of organic solvents, it requires expensive equipment and harsh operating conditions, making it difficult to promote and apply in conventional laboratories and industrial settings. There is an urgent need to develop a new extraction system that is green and low in toxicity, has adjustable components, is easy to operate, and is suitable for the enrichment of trace phenolic compounds in high-fat vegetable oil matrices.

[0005] Eutectic solvents (DES) are a novel class of green solvents formed by hydrogen bond donors and acceptors through intermolecular hydrogen bonding. They are characterized by simple preparation, tunable structure, low vapor pressure, and good biocompatibility, and have shown promising application prospects in the field of natural product extraction. Switchable DES, in particular, possess the characteristic of adjustable hydrophilic / hydrophobic states, allowing for phase transitions and target component separation in the extraction system through external condition adjustments. However, ordinary DES or conventional switchable DES often struggle to simultaneously achieve oil phase contact capability, polarity control capability, and selective recognition capability for target molecules when dealing with high-fat oil phase systems, limiting their further application in the enrichment of trace phenolic compounds in vegetable oils.

[0006] Previous studies have reported the use of switchable eutectic solvents for the extraction of polyphenols from plant solids. These methods typically rely on high-pressure hydrostatic pressing, grinding, and other methods to disrupt plant tissue structure and promote the release of intracellular polyphenols. This technology primarily addresses the release of active ingredients and solid-liquid mass transfer in solid plant tissues, but it cannot directly solve the problems of low migration efficiency and difficulty in selective enrichment of trace phenols in highly lipophilic plant oil systems due to oil phase barrier, polarity differences, and interference from nonpolar matrices. Furthermore, some methods use strong inorganic acids such as hydrochloric acid to induce solvent hydrophobicity restoration. While this can achieve phase transition control, it suffers from high corrosiveness, insufficient operational safety, and limited compatibility with food oil systems. Therefore, it is still necessary to develop a novel supramolecular eutectic extraction system suitable for highly lipophilic plant oil systems, capable of gently controlling hydrophilic and hydrophobic states, and improving the migration and enrichment efficiency of trace phenols.

[0007] Cyclodextrins (CDs) possess a unique cavity structure that is hydrophilic on the outside and hydrophobic on the inside, enabling them to form inclusion systems with various hydrophobic or weakly polar organic molecules through host-guest inclusion interactions. Existing technologies introduce cyclodextrins or their derivatives into eutectic solvent systems, further providing supramolecular recognition sites on top of the existing hydrogen bond network. This enhances the solubilization, migration, and enrichment capabilities of target compounds through hydrogen bonding, hydrophobic interactions, and inclusion interactions. However, existing cyclodextrin-modified eutectic solvent systems are only developed for solid plant raw materials and are not adapted to high-lipid liquid oil matrices with a high triglyceride content, failing to eliminate the phenolic mass transfer limitations caused by the polar barrier of the oil phase. Furthermore, existing switchable eutectic solvents all use strong inorganic acids for phase separation, lacking designs that use food-grade, mild, weak acids to regulate reversible hydrophilic-hydrophobic transitions. This makes it difficult to balance extraction selectivity, operational safety, and compatibility with food oil processing. A specialized extraction system for highly lipophilic plant oils, capable of mildly controlling phase state and efficiently enriching trace phenols, is still lacking. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a eutectic solvent for enriching oil polyphenols, comprising the following steps: Hydrogen bond donors and hydrogen bond acceptors are mixed and stirred under heating conditions until a clear and homogeneous binary eutectic solvent matrix is ​​formed; then an alkaline aqueous solution is added to switch the binary eutectic solvent matrix to a hydrophilic state, and then cyclodextrin is added and stirred to obtain the eutectic solvent. The hydrogen bond donor is selected from one of linalool, octanoic acid, and lauric acid; the hydrogen bond acceptor is selected from one of octanoic acid, nonanoic acid, and decanoic acid; and the hydrogen bond donor and the hydrogen bond acceptor are different compounds.

[0009] Preferably, the cyclodextrin is one of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, methyl-β-cyclodextrin, and sulfobutyl-β-cyclodextrin.

[0010] Preferably, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:(1~2).

[0011] Preferably, the alkaline aqueous solution is a NaOH solution with a mass-volume percentage concentration of 4%, and the amount of the alkaline aqueous solution added is 2~6 mL per milliliter of binary eutectic solvent matrix.

[0012] Preferably, the amount of cyclodextrin added is 100-150 mg per milliliter of binary eutectic solvent matrix.

[0013] Preferably, the heating conditions are 70~90 ℃.

[0014] Preferably, the stirring method is either vortex stirring or magnetic stirring; when using vortex stirring, the stirring is continuous for 0.5 to 1.0 min; when using magnetic stirring, the rotation speed is 90 to 130 rpm and the time is 0.5 to 1 min.

[0015] Another object of the present invention is to provide a eutectic solvent prepared by the above preparation method.

[0016] Preferably, the eutectic solvent is adjusted to a hydrophilic state by an alkaline aqueous solution and restored to a hydrophobic state by a citric acid aqueous solution.

[0017] Another object of the present invention is to provide the application of the eutectic solvent in the extraction of phenolic compounds from macadamia nut oil.

[0018] Preferably, the application includes: mixing macadamia nut oil with a eutectic solvent and then performing ultrasonic extraction; after extraction, adding citric acid aqueous solution and centrifuging to form a supramolecular eutectic solvent phase; and collecting the supramolecular eutectic solvent phase to obtain an extract of phenolic compounds from macadamia nut oil.

[0019] As a further preferred embodiment, the mass-to-volume ratio of the macadamia nut oil to the eutectic solvent is 1 g:(2~6) mL.

[0020] As a further preferred option, the conditions for ultrasonic extraction are: power 400 W, frequency 40 kHz, temperature 25~65℃, and time 10~30 min.

[0021] As a further preferred embodiment, the citric acid aqueous solution has a mass-volume percentage concentration of 20% to 60%, and the amount of citric acid aqueous solution added is 0.5 to 1.5 mL per milliliter of binary eutectic solvent matrix.

[0022] As a further preferred option, the centrifugation conditions are: a rotation speed of 5000 rpm and a time of 5 min.

[0023] The eutectic solvent of this invention is composed of cyclodextrin and a binary DES matrix, and is a supramolecular eutectic solvent (SDES). The binary eutectic solvent matrix is ​​constructed with fatty alcohols and / or fatty acid compounds, and cyclodextrin is further introduced as a supramolecular recognition component. The binary eutectic solvent matrix can adjust the polarity of the system through hydrogen bonding networks and hydrophobic interactions, thereby improving the compatibility between the oil matrix and the extraction phase. The cyclodextrin has a cavity structure that is hydrophilic on the outside and hydrophobic on the inside. It can enhance the recognition, solubilization and stabilization of trace phenolic compounds in macadamia nut oil through host-guest inclusion, and promote the migration of phenolic compounds from the oil phase to the supramolecular eutectic solvent phase, thereby achieving efficient enrichment of target phenolic compounds.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) By optimizing the composition of SDES and the amount of cyclodextrin added, the extraction liquid ratio (mass-volume ratio of macadamia oil to SDES), ultrasonic extraction temperature and time, etc., this invention significantly improves the enrichment effect and extraction efficiency of phenolic compounds in macadamia oil. Compared with the traditional ethanol extraction system, the SDES of this invention can more effectively overcome the compatibility difference between the high hydrophobicity of the oil matrix and the high polarity of polyphenol molecules, and improve the migration efficiency and enrichment effect of phenolic compounds in the extraction phase.

[0025] (2) The SDES constructed in this invention has the characteristics of selectivity and good adaptability: In view of the matrix characteristics of macadamia nut oil with high lipophilicity, low polarity and low content of phenolic compounds, this invention uses a low eutectic solvent matrix to adjust the polarity of the system and the contact ability of the oil phase, promotes the full miscibility of solvent and oil, and at the same time utilizes the host-guest recognition of phenolic molecules by the cyclodextrin cavity to effectively enhance the solubilization and directional enrichment of trace phenols in the extraction phase, and alleviate the mass transfer interference caused by the high lipophilic matrix.

[0026] (3) The present invention has multiple synergistic extraction mechanisms: the SDES of the present invention achieves synergistic solubilization and extraction by relying on the triple action of intermolecular hydrogen bonds, hydrophobic interactions, and cyclodextrin host-guest inclusion; Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy characterization combined with molecular theory calculations confirm that the reconstruction of solvent hydrogen bond network and supramolecular interaction mediated by cyclodextrin are the core mechanisms of the system’s high extraction performance.

[0027] (4) This invention has the characteristics of being green and low in toxicity, having a simple and mild process, and being highly compatible with food systems: This invention uses a low eutectic solvent and cyclodextrin to construct the extraction system, reducing the use of traditional organic solvents. The extraction process mainly includes steps such as mixing, ultrasonic-assisted extraction, and centrifugation. The operating conditions are mild and no complex equipment is required. At the same time, this invention uses citric acid as an acidification regulator to induce the hydrophilic supramolecular low eutectic solvent to restore its hydrophobicity and achieve phase separation. Compared with strong inorganic acids such as hydrochloric acid, citric acid has the characteristics of being widely available, inexpensive, less corrosive, safer, and more compatible with food systems. It can complete the regulation of the hydrophilic and hydrophobic states of the system and the enrichment of target components under milder conditions, which is conducive to reducing operational risks and subsequent application limitations, and is in line with the development direction of green extraction and high-value utilization of edible oils.

[0028] In summary, this invention has developed a supramolecular eutectic green extraction system and its supporting extraction process adapted to macadamia nut oil, providing a new and feasible technical path for the efficient enrichment of trace phenolic active ingredients in edible oils and the high-value utilization of macadamia nut oil resources through deep processing. Attached Figure Description

[0029] Figure 1 The figure shows the characterization spectra of SDES and its raw materials prepared in Example 1 of this invention; (a) is the Fourier transform infrared (FT-IR) spectrum; (b) is the nuclear magnetic resonance (NMR) spectrum. 1 H NMR spectrum; Figure 2 Figure 1 shows the total polyphenol content of macadamia oil under different extraction conditions; Figure 2(a) shows the total polyphenol content of macadamia oil under different mass-volume ratios (extraction material-liquid ratios) of macadamia oil to SDES; Figure 3(b) shows the total polyphenol content of macadamia oil under different ultrasonic extraction times; Figure 4(c) shows the total polyphenol content of macadamia oil under different ultrasonic extraction temperatures. Figure 3Figure 1 shows the phase behavior and reversible switching process of SDES prepared in Example 1 of this invention. Figure 1(a) shows the volume fraction change trend of the hydrophilic DES phase after treatment with different amounts of 4% (w / v) NaOH aqueous solution. Figure 2(b) shows the volume fraction change trend of the hydrophobic DES phase after treatment with different amounts of 40% (w / v) citric acid aqueous solution. Figure 3(c) corresponds to the potential change trend during the transition of the DES phase from hydrophobic to hydrophilic state in Figure 2(a). Figure 4(d) corresponds to the potential change trend during the transition of the DES phase from hydrophilic to hydrophobic state in Figure 2(b). Figure 5(e) is a schematic diagram of the reversible switching process of the DES phase changing from a single-phase hydrophilic SDES phase to a hydrophobic DES phase after alkali treatment and then being acidified with citric acid to restore the hydrophobic DES phase. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1 This embodiment provides a method for preparing SDES for enriching oil polyphenols, including the following steps: Weigh linalool (9.63 g, 0.0624 mol) and octanoic acid (9.0 g, 0.0624 mol), mix them, and add them to a brown sample bottle. Stir magnetically at 80 °C for 45 min until a clear and homogeneous binary DES matrix (linalool-octanoic acid) is formed. Take 10 mL of the binary DES matrix and then add 40 mL of 4% (w / v) NaOH solution and 1.25 g of hydroxypropyl-β-cyclodextrin. Vortex mix continuously for 0.5 min to obtain a homogeneous single-phase SDES.

[0032] Through FT-IR spectroscopy ( Figure 1 (a) and 1 H NMR spectrum ( Figure 1 In section (b), the SDES prepared in this example was characterized. The results showed that the main characteristic peaks of linalool, octanoic acid and hydroxypropyl-β-cyclodextrin could still be observed in the system. At the same time, the hydroxyl absorption peak broadened and shifted, indicating that hydrogen bonding and supramolecular interactions were formed in the system, proving that SDES was successfully prepared.

[0033] Application Example 1a This application example provides a method for extracting phenolic compounds from macadamia nut oil using SDES prepared in Example 1, comprising the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0034] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0035] The results showed that, under the above conditions, the total polyphenol extraction rate of macadamia nut oil was 46.50 μg GAE / g (calculated as gallic acid equivalent), which was higher than the total polyphenol extraction rate of the traditional 80% ethanol extraction system under the same conditions (21.05 μg GAE / g).

[0036] Under the optimal extraction conditions of Application Example 1a (macadamia oil to SDES mass-to-volume ratio of 1:4 g / mL, hydroxypropyl-β-cyclodextrin content of 125 mg / mL (based on the total volume of the binary DES matrix), extraction temperature of 35℃, and extraction time of 15 min), after extraction, the upper oil phase was removed, and 640 μL of 40% (w / v) citric acid aqueous solution was added to the lower polyphenol-containing SDES phase. After vortexing for 0.5 min, the mixture was centrifuged at 5000 rpm for 5 min. The results showed that the system re-separated after centrifugation, with the upper layer reverting to the hydrophobic DES phase and the lower layer being a water-salt phase enriched with polyphenols. This result indicates that citric acid can effectively neutralize NaOH, reversibly switching the DES phase from a hydrophilic to a hydrophobic state, thus achieving DES recovery and phenolic compound enrichment.

[0037] To verify the reversible switching capability of DES, a blank solvent phase switching experiment was conducted in the absence of macadamia nut oil: linalool was added at a molar ratio of 1:(1~2), and the mixture was magnetically stirred at 80 ℃ for 45 min until a clear and homogeneous binary DES matrix was formed. Then, 1 mL of the binary DES matrix was taken; 4 mL of 4% (w / v) NaOH aqueous solution was added, followed by 0.125 g of hydroxypropyl-β-cyclodextrin, and vortexed for 0.5 min to form a homogeneous SDES. Next, 800 μL of 40% (w / v) citric acid aqueous solution was added to the SDES, vortexed for 0.5 min, and then centrifuged at 5000 rpm for 5 min. The results are as follows: Figure 3 As shown in (e): the upper layer is restored to the initial DES phase of 1 mL, and the lower layer is the water-salt phase.

[0038] Therefore, the SDES prepared in Example 1 can complete the reversible switching from hydrophobic to hydrophilic to hydrophobic without the interference of grease, proving that this switching behavior is an inherent property of SDES, rather than being induced by the grease matrix.

[0039] Application Example 1b The difference between this application example and application example 1a is that the mass-to-volume ratio of macadamia nut oil to SDES is 1 g: 2 mL, meaning the volume of SDES is 2.0 mL. All other steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 2.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0040] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0041] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 31.79 μg GAE / g.

[0042] Application Example 1c The difference between this application example and application example 1a is that the mass-to-volume ratio of macadamia nut oil to SDES is 1 g:3 mL, meaning the volume of SDES is 3.0 mL. All other steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 3.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0043] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0044] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 37.52 μg GAE / g.

[0045] Application Example 1d The difference between this application example and application example 1a is that the mass-to-volume ratio of macadamia nut oil to SDES is 1 g: 5 mL, meaning the volume of SDES is 5.0 mL. All other steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 5.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0046] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0047] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 43.43 μg GAE / g.

[0048] Application Example 1e The difference between this application example and application example 1a is that the mass-to-volume ratio of macadamia nut oil to SDES is 1 g: 6 mL, meaning the volume of SDES is 6.0 mL. All other steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 6.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0049] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0050] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 40.50 μg GAE / g.

[0051] Application Example 1f The difference between this application example and application example 1a is that the ultrasonic extraction temperature is 25 ℃, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 25 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0052] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0053] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 43.04 μg GAE / g.

[0054] Application example 1g The difference between this application example and application example 1a is that the ultrasonic extraction temperature is 45 ℃, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 45 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0055] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0056] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 38.43 μg GAE / g.

[0057] Application Example 1h The difference between this application example and application example 1a is that the ultrasonic extraction temperature is 55 ℃, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 55 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0058] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0059] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 35.07 μg GAE / g.

[0060] Application Example 1i The difference between this application example and application example 1a is that the ultrasonic extraction temperature is 65 ℃, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 65 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0061] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0062] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 33.50 μg GAE / g.

[0063] Application Example 1j The difference between this application example and application example 1a is that the ultrasonic extraction time is 10 min, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 10 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0064] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0065] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 41.16 μg GAE / g.

[0066] Application Example 1k The difference between this application example and application example 1a is that the ultrasonic extraction time is 20 min, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 20 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0067] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0068] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 44.12 μg GAE / g.

[0069] Application Example 1l The difference between this application example and application example 1a is that the ultrasonic extraction time is 25 min, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 25 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0070] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0071] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 40.61 μg GAE / g.

[0072] Application Example 1m The difference between this application example and application example 1a is that the ultrasonic extraction time is 30 min, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 30 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0073] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0074] The results showed that, under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 40.28 μg GAE / g.

[0075] Example 2 This embodiment provides a method for preparing SDES for enriching oil polyphenols, including the following steps: Weigh linalool (9.63 g, 0.0624 mol) and octanoic acid (17.95 g, 0.1245 mol), mix them, and add them to a brown sample bottle. Stir magnetically at 80 °C until a clear and homogeneous binary DES matrix (linalool-octanoic acid) is formed. Take 10 mL of the binary DES matrix and then add 50 mL of 4% (w / v) NaOH aqueous solution and β-cyclodextrin (1.25 g). Vortex mix continuously for 0.5 min to obtain a homogeneous single-phase SDES.

[0076] Application Example 2 The difference between this application example and application example 1a is that the SDES prepared in Example 2 is used as the extraction system, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 2, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0077] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0078] The results showed that under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 28.42 μg GAE / g.

[0079] Example 3 This embodiment provides a method for preparing SDES for enriching oil polyphenols, including the following steps: Weigh linalool (9.63 g, 0.0624 mol) and octanoic acid (9.0 g, 0.0624 mol), mix them, and add them to a brown sample bottle. Stir magnetically at 70 °C until a clear and homogeneous binary DES matrix (linalool-octanoic acid) is formed. Take 10 mL of the binary DES matrix and then add 50 mL of 4% (w / v) NaOH solution and methyl-β-cyclodextrin (1.00 g). Vortex mix for 0.5 min to obtain a homogeneous single-phase SDES.

[0080] Application Example 3 The difference between this application example and application example 1a is that the SDES prepared in Example 3 is used as the extraction system, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 3, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0081] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0082] The results showed that under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 32.46 μg GAE / g.

[0083] Example 4 This embodiment provides a method for preparing SDES for enriching oil polyphenols, including the following steps: Weigh linalool (9.63 g, 0.0624 mol) and octanoic acid (13.51 g, 0.0937 mol), mix them, and add them to a brown sample bottle. Stir magnetically at 90 °C until a clear and homogeneous binary DES matrix (linalool-octanoic acid) is formed. Take 10 mL of the binary DES matrix and then add 60 mL of 4% (w / v) NaOH aqueous solution and 1.50 g of sulfobutyl-β-cyclodextrin. Vortex mix for 0.5 min to obtain a homogeneous single-phase SDES.

[0084] Application Example 4 The difference between this application example and application example 1a is that the SDES prepared in Example 4 is used as the extraction system, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of SDES prepared in Example 4, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the lower SDES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0085] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0086] The results showed that under the above conditions, the total polyphenol extraction rate in macadamia nut oil was 35.47 μg GAE / g.

[0087] Comparative Example 1 The difference between this comparative example and Example 1 is that cyclodextrin is not added; only linalool and octanoic acid are used to form DES. The remaining steps and parameters are the same as in Example 1, as follows: Weigh linalool (9.63 g, 0.0624 mol) and octanoic acid (9.0 g, 0.0624 mol), mix them, and add them to a brown sample bottle. Stir magnetically at 80 °C until a clear and homogeneous DES (linalool-octanoic acid) is formed. Then add 40 mL of 4% (w / v) NaOH solution and vortex mix for 0.5 min to obtain a homogeneous single-phase DES.

[0088] Comparative Application Example 1 The difference between this comparative application example and application example 1a is that the DES prepared in comparative example 1 is used as the extraction system, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of DES prepared in Comparative Example 1, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35 ℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the DES phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0089] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0090] The results showed that, under the above conditions, the total polyphenol extraction rate from macadamia nut oil in Comparative Application Example 1 was 23.14 μg GAE / g. Without the introduction of cyclodextrin, the enrichment capacity of the extraction system for phenolic compounds was reduced, indicating that the host-guest inclusion effect of β-cyclodextrin and its derivatives, as well as the synergistic effect with the hydrogen bonding network of the eutectic solvent, plays an important role in improving the extraction efficiency of phenolic compounds from macadamia nut oil.

[0091] Comparative Application Example 2 The difference between this comparative application example and application example 1a is that 80 wt% ethanol is used as the extraction system, while the remaining steps and parameters are the same as in application example 1a, specifically including the following steps: (1) Accurately weigh 1.0 g of macadamia nut oil into a centrifuge tube, add 4.0 mL of 80wt% ethanol, vortex (120 rpm) for 0.5 min until homogeneous; then place it in an ultrasonic cleaner (400 W power, 40 kHz frequency) and ultrasonically extract at 35℃ for 15 min; after extraction, centrifuge at 5000 rpm for 5 min, collect the ethanol phase, and obtain the extract of phenolic compounds from macadamia nut oil.

[0092] (2) The total polyphenol content in the extract was determined by the Folin-Ciocalteu method: 0.5 mL of macadamia nut oil phenolic compound extract was accurately pipetted, 1.0 mL of Folin reagent was added, and the mixture was reacted in the dark for 5 min. Then, 3.0 mL of 7.5% (w / v) Na2CO3 solution was added, and the mixture was reacted in the dark at 25 ℃ for 120 min. The absorbance was measured at a wavelength of 765 nm, and the total polyphenol content was calculated by plotting a standard curve using gallic acid standard.

[0093] The results showed that, under the above conditions, the total polyphenol extraction rate of macadamia nut oil in Comparative Application Example 2 was 21.05 μg GAE / g. The extraction effect of this comparative application example was lower than that of the SDES extraction system in Application Example 1a, indicating that the SDES extraction system in Application Example 1a can more effectively promote the migration and enrichment of phenolic compounds in the oil matrix.

[0094] The total polyphenol extraction rates of various application examples of this invention are summarized in Table 1: Table 1. Effects of different cyclodextrin extraction systems on the extraction efficiency of phenolic compounds from macadamia nut oil. In summary, compared with the binary DES extraction system, the SDES extraction system of the present invention significantly improves the total polyphenol extraction rate of macadamia nut oil, indicating that the SDES extraction system of the present invention can effectively promote the migration and enrichment of phenolic compounds in the oil matrix.

[0095] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a eutectic solvent for enriching oil and fat polyphenols, characterized in that, Includes the following steps: Hydrogen bond donors and hydrogen bond acceptors are mixed and stirred under heating conditions until a homogeneous binary eutectic solvent matrix is ​​formed; then an alkaline aqueous solution is added first, followed by cyclodextrin, and the mixture is stirred to obtain the eutectic solvent. The hydrogen bond donor is selected from one of linalool, octanoic acid, and lauric acid; the hydrogen bond acceptor is selected from one of octanoic acid, nonanoic acid, and decanoic acid; and the hydrogen bond donor and the hydrogen bond acceptor are different compounds.

2. The method for preparing a eutectic solvent for enriching oil polyphenols according to claim 1, characterized in that, The cyclodextrin is one of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, methyl-β-cyclodextrin, and sulfobutyl-β-cyclodextrin.

3. The method for preparing a eutectic solvent for enriching oil polyphenols according to claim 1, characterized in that, The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:(1~2).

4. The method for preparing a eutectic solvent for enriching oil polyphenols according to claim 1, characterized in that, The alkaline aqueous solution is a NaOH solution with a mass-volume percentage concentration of 4%, and the amount of the alkaline aqueous solution added is 2~6 mL per milliliter of binary eutectic solvent matrix.

5. The method for preparing a eutectic solvent for enriching oil polyphenols according to claim 1, characterized in that, The amount of cyclodextrin added is 100-150 mg per milliliter of binary eutectic solvent matrix.

6. The method for preparing a eutectic solvent according to claim 1, characterized in that, The heating conditions are 70~90℃.

7. The eutectic solvent prepared by the method according to any one of claims 1 to 6.

8. The application of the eutectic solvent of claim 7 in the extraction of phenolic compounds from macadamia nut oil.

9. The application according to claim 8, characterized in that, The application includes: mixing macadamia nut oil with a eutectic solvent and then performing ultrasonic extraction; after extraction, adding citric acid aqueous solution and centrifuging to form a supramolecular eutectic solvent phase; and collecting the supramolecular eutectic solvent phase to obtain an extract of phenolic compounds from macadamia nut oil.

10. The application according to claim 9, characterized in that, The mass-to-volume ratio of macadamia nut oil to eutectic solvent is 1 g:(2~6) mL; the ultrasonic extraction conditions are: power 400 W, frequency 40 kHz, temperature 25~65 ℃, time 10~30 min; the mass-to-volume percentage concentration of the citric acid aqueous solution is 20%~60%, and the amount of citric acid aqueous solution added per milliliter of binary eutectic solvent matrix is ​​0.5~1.5 mL.

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