A composite Antarctic krill oil gel and preparation method thereof

Abstract

The present application discloses a composite Antarctic krill oil gel and a preparation method thereof, belonging to the technical field of gel preparation. The gel comprises the following components by mass: 2-5% amidated pectin aerogel template, 95-98% krill peptide capillary suspension. The present invention prepares Antarctic krill oil gel by a composite method, combining the aerogel template method and the capillary suspension, which has both high mechanical strength and can adjust its rheological properties. The preparation process conditions are mild, and will not affect the krill oil and the loaded active substances, and the properties are stable and biodegradable, and it is an ideal carrier.

Description

Technical Field

[0001] The present application belongs to the technical field of gel preparation, and specifically relates to a composite Antarctic krill oil gel, a preparation method and an application thereof. Background Art

[0002] As an emerging source of high-quality Omega-3 fatty acids, Antarctic krill oil is widely used in food, health food, biopharmaceuticals and other industries. It contains rich phospholipid n-3 polyunsaturated fatty acids and astaxanthin, which have been proven to have good antioxidant and anti-inflammatory effects in various studies. Although Antarctic krill oil has a variety of soft capsule products as a health food, the single dosage form limits the application of Antarctic krill oil.

[0003] Oleogel is a gel formed by fixing the oil phase through a three-dimensional network structure formed by an organic gel factor. At present, the research on oleogel is mainly focused on the fields of food, medicine and cosmetics. As a substitute for saturated fatty acids, it can load volatile components, promote the skin penetration of non-polar compounds, or serve as a raw material for 3D printed food. The development of Antarctic krill oil gel can change its physical properties, increase its loading capacity for water-soluble substances, and make it meet the needs of different application scenarios. Among the preparation methods of oleogel, the aerogel template method has received attention in recent years.

[0004] Aerogels have a highly porous structure, a complex three-dimensional network, and a large specific surface area. The use of aerogels to prepare oleogels can provide high oil absorption and oil retention capacity. Aerogels adsorb krill oil through surface tension and capillary forces to convert into oleogels. Compared with pre-mixed oleogels, the production and transportation of aerogels are more cost-effective, and the aerogel template method is more suitable for loading heat-sensitive substances because it only involves physical processes.

[0005] Capillary suspensions can be produced by adding a small amount of immiscible secondary fluid (such as water) to a suspension of particles dispersed in a primary fluid (such as oil). Stirring causes the particles to bind together through capillary forces to form a spatial network. Capillary suspensions have adjustable rheological properties, and the mechanical properties of oil gels prepared by capillary suspensions are easier to control to meet the needs of different scenarios.

[0006] At present, there are few reports on the preparation of Antarctic krill oil gel using amidated pectin aerogel template and krill peptide capillary suspension. The present invention can provide technical support for research and application in this field. Summary of the invention

[0007] In order to solve the above problems, a composite Antarctic krill oil gel and a preparation method thereof are provided. The present invention prepares the Antarctic krill oil gel by a composite method, combining the aerogel template method and the capillary suspension, which not only has high mechanical strength, but also can adjust its rheological properties. The preparation process conditions are mild, will not affect the krill oil and the loaded active substances, and has stable properties and good biodegradability, and is an ideal carrier.

[0008] On one hand, the present invention provides a composite Antarctic krill oil gel, which comprises the following components in parts by weight: 2-5% of an amidated pectin aerogel template and 95-98% of a krill peptide capillary suspension.

[0009] Optionally, the gel comprises the following components in proportions by mass: 2-3% of amidated pectin aerogel template and 97-98% of krill peptide capillary suspension.

[0010] Optionally, the amidated pectin aerogel template is prepared by freeze-drying an amidated pectin solution using an aqueous solution of tert-butyl alcohol as a solvent.

[0011] Optionally, the krill peptide capillary suspension is prepared by constructing a ternary liquid / liquid / solid system with krill peptides as suspended particles, Antarctic krill oil as a first solvent, and pure water as a second solvent.

[0012] Another aspect of the present invention provides a method for preparing the above-mentioned composite Antarctic krill oil gel, the preparation method comprising the following steps:

[0013] (1) adding the amidated pectin solution into the tert-butyl alcohol aqueous solution to obtain a mixed solution;

[0014] (2) cross-linking the mixed solution in step (1) for 3-6 hours, pre-freezing it, and then freeze-drying it for 30-40 hours to obtain an amidated pectin aerogel template;

[0015] (3) adding 10-30 wt % of krill peptide to the Antarctic krill oil, homogenizing and shearing the mixture, and then immersing the amidated pectin aerogel template obtained in step (2) into the Antarctic krill oil to obtain an oil phase system;

[0016] (4) adding 0.2-0.3 wt % pure water to the oil phase system of step (3), and then homogenizing and shearing the mixture to obtain a composite Antarctic krill oil gel.

[0017] Optionally, the pH value of the amidated pectin solution is 3.5-4.5, and the weight content percentage is 1-3wt%.

[0018] Optionally, the volume of the tert-butyl alcohol aqueous solution is the same as that of the amidated pectin solution, and the tert-butyl alcohol aqueous solution contains 60-80% v / v of tert-butyl alcohol and 1-3wt% of Zn 2+ .

[0019] Optionally, the pre-freezing condition of step (2) is to pre-freeze the mixed solution at a temperature of -30°C to -40°C until the mixed solution is completely solidified.

[0020] Optionally, the homogenization and shearing conditions in step (3) are homogenization at 1500-2500 rpm for 10-15 min, and the homogenization and shearing conditions in step (4) are homogenization at 1500-2500 rpm for 10-15 min.

[0021] In another aspect, the present invention provides a use of the composite Antarctic krill oil gel as described above, and / or the composite Antarctic krill oil gel prepared by the method for preparing the composite Antarctic krill oil gel as described above in the preparation of food, health food or drug carrier.

[0022] The beneficial effects of this application include but are not limited to:

[0023] 1. The composite Antarctic krill oil gel provided in the present application adopts the aerogel template method to prepare the oil gel, has high oil absorption and oil holding performance, high mechanical strength, and does not require complex organic solvents during the preparation process;

[0024] 2. The composite Antarctic krill oil gel provided in the present application, amidated pectin has the potential to form high-strength hydrogels under minimal restrictive conditions, and the requirements for gelation conditions can be reduced in the process of preparing aerogel templates;

[0025] 3. The composite Antarctic krill oil gel provided in the present application uses a tert-butyl alcohol aqueous solution as a solvent in the preparation process of the amidated pectin aerogel template, which not only enhances the hydrophobic interaction between the pectin chains, but also makes it more volatile during freeze-drying, thereby improving the efficiency of freeze-drying;

[0026] 4. The composite Antarctic krill oil gel provided in the present application uses Antarctic krill peptides as water-soluble particles, which can preferentially combine with a small amount of water in the oil to form a three-dimensional network connected by capillary bridges, making the rheological properties of the oil gel easy to adjust;

[0027] 5. The preparation method of the composite Antarctic krill oil gel provided in this application is simple and has strong versatility, which expands the application direction of Antarctic krill oil in the fields of medicine and food. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0029] Figure 1 It is a schematic diagram of the oil absorption of the composite Antarctic krill oil gel involved in the examples and comparative examples of the present application.

[0030] Figure 2 It is a schematic diagram of the oil retention of the composite Antarctic krill oil gel involved in the examples and comparative examples of the present application. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the overall concept of the present invention, a detailed description is given below by way of examples.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0033] In the present invention, unless otherwise clearly specified and limited, the first feature "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0034] Hereinafter, the composite Antarctic krill oil gel and the preparation method thereof of the present invention will be described in detail in conjunction with exemplary embodiments.

[0035] The composite Antarctic krill oil gel provided by the present invention comprises the following components in mass fractions: 2-5% of amidated pectin aerogel template and 95-98% of krill peptide capillary suspension. Further, the gel comprises the following components in mass fractions: 2-3% of amidated pectin aerogel template and 97-98% of krill peptide capillary suspension.

[0036] In an exemplary embodiment of the present invention, the preparation method of the composite Antarctic krill oil gel provided by the present invention comprises the following steps:

[0037] (1) Add an amidated pectin solution having a pH value of 3.5-4.5 and a weight content of 1-3 wt % to an equal volume of tert-butyl alcohol aqueous solution to obtain a mixed solution.

[0038] Specifically, the tert-butyl alcohol aqueous solution contains 60-80% v / v of tert-butyl alcohol and 1-3wt% of Zn 2+ . Tert-butyl alcohol has the characteristics of high freezing point, high vapor pressure, low toxicity, etc. It is easier to sublime and can improve the efficiency of freeze-drying. In addition, when tert-butyl alcohol is added to the aqueous solution, it can form needle-shaped crystals when frozen, increasing the surface area. At the same time, the tubular channels left after the ice crystals sublimate are conducive to the flow of water vapor and accelerate drying. Such a solution ratio can shorten the freeze-drying time and reduce costs while ensuring that the amidated pectin is fully cross-linked to form a gel.

[0039] (2) The mixed solution in step (1) is cross-linked for 3-6 hours, pre-frozen, and then freeze-dried for 30-40 hours to obtain an amidated pectin aerogel template.

[0040] Specifically, pectin can cross-link with divalent metal ions to form gel under this condition. Pre-freezing is carried out after sufficient cross-linking. The pre-freezing condition is to pre-freeze at a temperature of -30°C to -40°C until the mixed solution is completely solidified. If the pre-freezing temperature is too low, it will cause energy waste; if the pre-freezing temperature is above -30°C, although the solidification eutectic point can be reached, in order to make the gel form a structurally stable ice crystal structure at a faster cooling rate, the pre-freezing temperature is -30°C to -40°C. The set freeze-drying time can ensure that the gel is fully sublimated and reduce solvent residues.

[0041] (3) Add 10-30wt% krill peptide to the Antarctic krill oil, and homogenize at 1500-2500rpm for 10-15min. Krill peptide has good antioxidant capacity, can remove free radicals, reduce oxidative damage to the body, reduce oxidation of krill oil, and improve the stability of oil gel. Homogenization under this condition can fully mix the krill peptide with the Antarctic krill oil. Then, immerse the amidated pectin aerogel template obtained in step (2) in the Antarctic krill oil to obtain an oil phase system.

[0042] (4) adding 0.2-0.3 wt% pure water to the oil phase system of step (3), and then homogenizing at 1500-2500 rpm for 10-15 min. Since water preferentially combines with hydrophilic particles, after uniform mixing, a three-dimensional network structure connected by water as capillary bridges is formed in the oil solvent to obtain a composite Antarctic krill oil gel.

[0043] The present invention prepares Antarctic krill oil gel by using an amidated pectin aerogel template and a krill peptide capillary suspension. Amidated pectin is obtained by converting part of the methyl ester into an amide group during the preparation of high-ester pectin, so that less divalent metal ions are required for gelation, pre-gelation is not easy to occur, and it has good thermal reversibility, and has the potential to form a high-strength hydrogel under minimal restrictive conditions. The composite Antarctic krill oil gel of the present application has the advantages of simple preparation method, high mechanical strength, good oil absorption and oil retention, etc. It can be used as a carrier to load a variety of functional substances, which broadens the direction for the application of Antarctic krill oil.

[0044] Example 1

[0045] This example uses the above preparation method to prepare a composite Antarctic krill oil gel, and the specific steps are as follows:

[0046] (1) adding a 2 wt % amidated pectin solution with a pH value of 4.0 to an equal volume of a tert-butyl alcohol aqueous solution, wherein the tert-butyl alcohol aqueous solution contains 80% v / v tert-butyl alcohol and 2 wt % (relative to the amidated pectin) of Zn2+;

[0047] (2) after cross-linking the above solution for 4 hours, pre-freeze at -40°C until the solution is completely solidified, and then freeze-dry for 36 hours to obtain an aerogel template;

[0048] (3) adding 20 wt % of krill peptide to Antarctic krill oil, homogenizing and shearing at 2000 rpm, and then immersing the obtained aerogel template in Antarctic krill oil to replace the solvent with the oil phase;

[0049] (4) adding 0.2 wt% pure water to the system of (3), and homogenizing and shearing at 2000 rpm to make the suspended krill peptide particles connected into a three-dimensional network through water capillary bridges to obtain Antarctic krill oil gel.

[0050] Example 2

[0051] This example uses the above preparation method to prepare another composite Antarctic krill oil gel, and the specific steps are as follows:

[0052] (1) adding a 1 wt % amidated pectin solution having a pH value of 4.0 to an equal volume of a tert-butyl alcohol aqueous solution, wherein the tert-butyl alcohol aqueous solution contains 60% v / v tert-butyl alcohol and 1 wt % (relative to the amidated pectin) of Zn2+;

[0053] (2) after cross-linking the above solution for 4 hours, pre-freeze at -40°C until the solution is completely solidified, and then freeze-dry for 36 hours to obtain an aerogel template;

[0054] (3) adding 10 wt % of krill peptide to the Antarctic krill oil, homogenizing and shearing at 2000 rpm, and then immersing the obtained aerogel template in the Antarctic krill oil to replace the solvent with the oil phase;

[0055] (4) adding 0.2 wt% pure water to the system of (3), and homogenizing and shearing at 2000 rpm to make the suspended krill peptide particles connected into a three-dimensional network through water capillary bridges to obtain Antarctic krill oil gel.

[0056] Example 3

[0057] This example uses the above preparation method to prepare another composite Antarctic krill oil gel, and the specific steps are as follows:

[0058] (1) adding a 3 wt % amidated pectin solution having a pH value of 4.0 to an equal volume of a tert-butyl alcohol aqueous solution, wherein the tert-butyl alcohol aqueous solution contains 70% v / v tert-butyl alcohol and 3 wt % (relative to the amidated pectin) of Zn2+;

[0059] (2) after cross-linking the above solution for 4 hours, pre-freeze at -40°C until the solution is completely solidified, and then freeze-dry for 36 hours to obtain an aerogel template;

[0060] (3) adding 30 wt % of krill peptide to Antarctic krill oil, homogenizing and shearing at 2000 rpm, and then immersing the obtained aerogel template in Antarctic krill oil to replace the solvent with the oil phase;

[0061] (4) adding 0.3 wt% pure water to the system of (3), and homogenizing and shearing at 2000 rpm to make the suspended krill peptide particles connected into a three-dimensional network through water capillary bridges to obtain Antarctic krill oil gel.

[0062] Comparative Example 1

[0063] In this comparative example, a comparative Antarctic krill oil gel was prepared by the same preparation method as in Example 1, except that high ester pectin was used instead of amidated pectin in step (1).

[0064] Comparative Example 2

[0065] In this comparative example, another comparative Antarctic krill oil gel was prepared by the same preparation method as in Example 1, except that ethanol was used instead of tert-butanol in step (1).

[0066] Comparative Example 3

[0067] In this comparative example, another comparative Antarctic krill oil gel was prepared by the same preparation method as in Example 1, except that starch was used instead of krill peptide in step (3).

[0068] 1. Determination of oil absorption

[0069] The oil absorption was determined by weighing the aerogel template and immersing it in Antarctic krill oil mixed with krill peptides or starch according to the preparation method of each embodiment and comparative example. After sufficient oil absorption, the residual oil on the surface of the oil gel was removed. The obtained oil gel was immediately weighed, and the oil absorption was calculated using the following formula: Oil absorption = (weight of the generated oil gel - initial weight of the aerogel) / initial weight of the aerogel. The obtained oil absorption test results are shown in Figure 2. Figure 1 .

[0070] like Figure 1 As shown, the oil absorption of each embodiment is about 50g / g, and the oil absorption of comparative example 1 is the lowest, which is only 28.6g / g. Since the oil is stored in the gaps of the aerogel network after the aerogel is converted into an oil gel, the pore size of the aerogel determines the oil absorption capacity of the aerogel. Comparative example 1 replaces the amidated pectin with high-ester pectin. High-ester pectin has higher requirements for gelling conditions and cannot effectively form gel under the same conditions, so the oil absorption is poor. Comparative example 2 replaces tert-butanol with ethanol. The role of tert-butanol is to enhance the hydrophobic interaction between pectin chains, making it easier to gel. At the same time, tert-butanol has a higher vapor pressure and a lower melting volume, which can improve the efficiency of freeze-drying and prevent problems such as collapse of the aerogel structure; therefore, the aerogel of the embodiment has a more intact structure after freeze-drying and a stronger oil absorption.

[0071] 2. Determination of oil holding capacity

[0072] The oil holding capacity was determined by weighing the Antarctic krill oil gel samples prepared in each example and comparative example and placing them between two pieces of oil absorbing paper. Subsequently, they were placed in a centrifuge tube. The Antarctic krill oil gel was then centrifuged at 8000 rpm for 15 minutes. The oil holding capacity was calculated using the following formula: Oil holding capacity (%) = mass of oil gel after centrifugation / mass of oil gel before centrifugation × 100%. The obtained oil holding capacity test results are shown in Figure 1. Figure 2 .

[0073] like Figure 2 As shown, the oil holding capacity of the Antarctic krill oil gel prepared in each embodiment is about 50%, with the lowest in Comparative Example 1, which is only 23.1%, and Comparative Example 2 being 27.9%. Since the binding of oil in aerogels depends on capillary action and surface tension, the greater the capillary force, the higher the oil holding capacity of the aerogel. Comparative Example 1 has a low degree of crosslinking, a large gap inside the gel, and a small capillary force, so the oil binding capacity is low; while Comparative Example 2 has a structural collapse, which affects its oil holding performance. The aerogel preparation process of Comparative Example 3 is the same as that of Example 1, but since the binding of starch to water is not as tight as that of krill peptide, the overall oil holding capacity is reduced in the end.

[0074] 3. Viscosity measurement

[0075] The viscosity determination method is: using a rotational viscometer to measure the viscosity of the Antarctic krill oil gel prepared in each embodiment and comparative example at 25° C. The obtained viscosity test results are shown in Table 1.

[0076] Table 1 Viscosity test results

[0077]

[0078] The viscosity of Antarctic krill oil gel is determined by the performance of aerogel and the performance of capillary suspension. As shown in Table 1, each embodiment shows good viscosity, while the viscosity of the comparative example is significantly lower than that of the embodiment. Comparative Examples 1 and 2 cannot effectively support the structure of Antarctic krill oil gel because of the poor performance of aerogel. Comparative Example 3 uses starch instead of krill peptide, because the hydrophilicity of starch is weaker than that of krill peptide, and the strength of the capillary suspension formed is lower, which is not as good as krill peptide in improving the mechanical properties of oil gel.

[0079] 4. Storage stability determination

[0080] The storage stability determination method is as follows: 1 g of the Antarctic krill oil gel obtained in each embodiment and comparative example is placed at 25±2°C and 60±5% humidity to monitor the content of the main nutrients, and samples are taken every 3 months until the end of the 12th month. The stability of the sample is evaluated by the loss rate of nutrients. The loss rate is calculated using the following formula: Loss rate (%) = (initial mass of the substance - remaining mass of the substance) / initial mass of the substance × 100%. The loss rate test results of the main nutrients obtained are shown in Table 2.

[0081] Table 2 Test results of loss rate of main nutrients

[0082]

[0083] As shown in Table 2, the stability of the Antarctic krill oil gel samples prepared in each embodiment and comparative example under long-term storage conditions was compared by the loss rate of astaxanthin and phospholipids. Each embodiment showed very good stability. After 12 months of storage, the loss rates of astaxanthin and phospholipids were both within 3%. Comparative Example 1 had the worst stability. After 12 months, the loss rates of astaxanthin and phospholipids reached more than 13%, because Comparative Example 1 had the lowest structural strength and a low degree of cross-linking, and could not effectively protect the nutrients in the oil. It can be seen that the krill oil gel prepared by the present invention can significantly improve the stability of the nutrients in krill oil during storage.

[0084] The above is only the embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims

1. A composite Antarctic krill oil gel, characterized in that: The gel comprises the following components in percentage by mass: 2-5% of an amidated pectin aerogel template and 95-98% of a krill peptide capillary suspension; the amidated pectin aerogel template is prepared by freeze-drying an amidated pectin solution with a tert-butyl alcohol aqueous solution as a solvent; The preparation process of composite Antarctic krill oil gel is as follows: (1) adding the amidated pectin solution into the tert-butyl alcohol aqueous solution to obtain a mixed solution; (2) cross-linking the mixed solution in step (1) for 3-6 hours, pre-freezing it, and then freeze-drying it for 30-40 hours to obtain an amidated pectin aerogel template; (3) adding 10-30 wt % of krill peptide to the Antarctic krill oil, homogenizing and shearing the mixture, and then immersing the amidated pectin aerogel template obtained in step (2) into the Antarctic krill oil to obtain an oil phase system; (4) adding 0.2-0.3 wt% of pure water to the oil phase system of step (3), and then homogenizing and shearing the mixture to obtain a composite Antarctic krill oil gel; The pH value of the amidated pectin solution is 3.5-4.5, and the weight content percentage is 1-3wt%; The volume of the tert-butyl alcohol aqueous solution is the same as that of the amidated pectin solution, and the tert-butyl alcohol aqueous solution contains 60-80% v / v of tert-butyl alcohol and 1-3wt% of Zn 2+ .

2. The composite Antarctic krill oil gel according to claim 1, characterized in that: The gel comprises the following components in percentage by mass: 2-3% of amidated pectin aerogel template and 97-98% of krill peptide capillary suspension.

3. A method for preparing the composite Antarctic krill oil gel according to claim 1, characterized in that: The preparation method comprises the following steps: (1) adding the amidated pectin solution into the tert-butyl alcohol aqueous solution to obtain a mixed solution; (2) cross-linking the mixed solution in step (1) for 3-6 hours, pre-freezing it, and then freeze-drying it for 30-40 hours to obtain an amidated pectin aerogel template; (3) adding 10-30 wt % of krill peptide to the Antarctic krill oil, homogenizing and shearing the mixture, and then immersing the amidated pectin aerogel template obtained in step (2) into the Antarctic krill oil to obtain an oil phase system; (4) adding 0.2-0.3 wt% of pure water to the oil phase system of step (3), and then homogenizing and shearing the mixture to obtain a composite Antarctic krill oil gel; The pH value of the amidated pectin solution is 3.5-4.5, and the weight content percentage is 1-3wt%; The volume of the tert-butyl alcohol aqueous solution is the same as that of the amidated pectin solution, and the tert-butyl alcohol aqueous solution contains 60-80% v / v of tert-butyl alcohol and 1-3wt% of Zn 2+ .

4. The method for preparing the composite Antarctic krill oil gel according to claim 3, characterized in that: The pre-freezing condition of step (2) is to pre-freeze the mixed solution at a temperature of -30°C to -40°C until the mixed solution is completely solidified.

5. The method for preparing the composite Antarctic krill oil gel according to claim 3, characterized in that: The homogenization shearing conditions in step (3) are homogenization at 1500-2500 rpm for 10-15 min, and the homogenization shearing conditions in step (4) are homogenization at 1500-2500 rpm for 10-15 min.

6. Use of the composite Antarctic krill oil gel as claimed in any one of claims 1 to 2 or the composite Antarctic krill oil gel prepared by the preparation method of the composite Antarctic krill oil gel as claimed in any one of claims 3 to 5 in the preparation of food, health food or drug carrier.

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