Highly efficient and stable emulsion based on shellfish nanocrystals, and preparation method and application thereof

Abstract

The present application relates to the technical field of materials, in particular to a kind of high-efficiency stable emulsion based on shellfish nanocrystal and its preparation method and application, the emulsion preparation method includes the following steps: (1) the shellfish nanoparticles obtained by ultrafiltration separation is gradient settled with alcohol solvent, to obtain the shellfish nanoparticles with higher surface amphiphilicity and concentrated particle size distribution, which is freeze-dried to obtain shellfish nanocrystal;(2) the shellfish nanocrystal is dissolved with distilled water or buffer aqueous solution to obtain the water phase system, which is homogenized with oil phase system to obtain the high-efficiency stable emulsion based on shellfish nanocrystal.The present application uses nanocrystal in the heat extraction or heat processing of shellfish as emulsion interface stabilizer, which is widely sourced and does not need chemical modification, green and safe;Its interface emulsification stable effect is high-efficiency, and can tolerate acid and alkali, high temperature and salt ion, greatly widen the practical application range of shellfish nanocrystal and provide a new technology and new stabilizer for the preparation of high-stable emulsion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a high-efficiency and stable emulsion based on nano-crystals of shellfish and a preparation method and application thereof. BACKGROUND

[0002] The process of uniformly dispersing and mixing oil and water into a new phase is called emulsification. The emulsion obtained by emulsification is usually a thermodynamically unstable dispersion system. In order to achieve the best effect of emulsification, traditional emulsifiers such as lecithin, Tween, Span and other surfactants are widely used in this field. In recent years, with the rise of new product forms such as nano-emulsion, new emulsifiers with micro-nano size are becoming a popular application hotspot.

[0003] Pickering emulsion is a new type of emulsion stabilized by solid particles instead of traditional surfactants. Compared with traditional emulsions, Pickering emulsions have superior emulsification effect, lower toxicity and stronger emulsion stability, and therefore have excellent application prospects in the fields of food, medicine and cosmetics.

[0004] Currently, micro-nano particles used to stabilize Pickering emulsion are mainly inorganic and synthetic polymers. Although they have good interface stability, they have low biocompatibility, potential toxicological risk and complex preparation, which greatly limits the practical application and popularization of Pickering emulsion. Food ingredients such as proteins and polysaccharide colloidal particles have great advantages in the preparation and application of Pickering emulsion due to their biodegradable, green and natural or edible properties.

[0005] However, compared with the former artificial inorganic or polymer materials, natural polysaccharides are usually too hydrophilic or hydrophobic, and need to be modified to effectively stabilize Pickering emulsion. Proteins also need to be surface modified or combined with ingredients to improve stability due to their conformational stability. At the same time, the demand for Pickering high internal phase emulsion in the market is increasing. High internal phase emulsion is a kind of emulsion system with dominant oil content (oil phase usually higher than 74%), and the emulsification performance required for different oils is not consistent, so the demand for nano-particles with interface stability is higher. Therefore, finding natural compounds with complementary hydrophilic and hydrophobic properties, interface stability and broad-spectrum application for stabilizing Pickering emulsion has become an industry development trend.

[0006] There are rich mucin polysaccharides and amphipathic compounds (AC) in shellfish, and the comprehensive utilization of these components in the industry is still far from enough. SUMMARY

[0007] The present application is to overcome the defects in the prior art that the mucin polysaccharides and amphipathic components in shellfish are not fully utilized, and provides a high-efficiency and stable emulsion based on shellfish nanocrystals and a preparation method and application thereof.

[0008] To achieve the above-mentioned application purposes, the present application is realized by the following technical solutions:

[0009] In the first aspect, the present application first provides a preparation method of a high-efficiency and stable emulsion based on shellfish nanocrystals,

[0010] comprising the following steps:

[0011] (1) Separation of shellfish nanocrystals: the shellfish nanocrystals (macro category) obtained by ultrafiltration separation are gradiently settled by using an alcohol solvent, to obtain shellfish nanocrystals (sub category) with high amphiphilic property and concentrated particle size distribution, and the shellfish nanocrystals rich in amphiphilic components are obtained after freeze-drying and stored at-20℃ for standby use.

[0012] (2) Preparation of stable Pickering emulsion using shellfish nanocrystals rich in amphiphilic components: the amphiphilic shellfish nanocrystals are dissolved in distilled water or buffer aqueous solution to obtain an aqueous phase system, and the aqueous phase system is homogenized with an oil phase system to obtain the high-efficiency and stable emulsion based on shellfish nanocrystals.

[0013] The present inventors found in the early stage that when shellfish cells are heated, amphiphilic substances on the cell membrane and cytoplasmic contents will gradually migrate into the water phase, and under certain conditions, a delicate nanogel structure is formed, such as nanocrystals (nanocyclotella) in river clam soup. The nanocyclotella is resistant to high temperature, acid and alkali, and thus the development and application thereof has attracted attention from the academic and industrial circles. Since the nanoparticles can be used as an interfacial stabilizer of emulsion, the nanometer structure formed by the amphipathic components (amphipathic compounds, AC) such as phospholipids and glycolipids on the cell membrane of shellfish and components such as shellfish mucin and polysaccharides under induction conditions can be used as a natural green emulsion interfacial stabilizer.

[0014] The composition and hydrophilic-hydrophobic properties of the amphiphilic substance will result in different interface stability of the nanocrystals. Based on the different hydrophilic-hydrophobic properties of the amphiphilic substance carried by the shellfish nanoparticles, the solubility of the shellfish nanoparticles in alcohol is different, and the shellfish nanoparticles of different hydrophilic-hydrophobic properties are separated by using alcohol as an inducer to obtain shellfish nanocrystals with the best interface stability. The shellfish nanocrystals can act as a surfactant in the process of emulsifying oil-water two-phase liquid, and the interface stability of the screened shellfish nanocrystals is better than that of the un-screened shellfish nanocrystals. The amphiphilic shellfish nanocrystals obtained by selective screening have excellent emulsion interface stabilizer properties, can enhance the thermal stability, acid-base stability and ionic stability of the emulsion, and are green, natural, efficient and stable, and widely applicable.

[0015] Through actual test, the shellfish nanocrystal-based emulsion with high efficiency and stability has an enhanced stability of more than 50% under acidic conditions, and remains stable in a wide temperature range, and the release amount of the content marker is less than 1%.

[0016] Preferably, the shellfish nanoparticles in step (1) are obtained by heating the shellfish in hot water at 80-120°C for 10-200 min, centrifugation and ultrafiltration with a molecular weight cut-off of 10-300 KDa, to obtain shellfish nanoparticles with a high surface amphiphilicity and a particle size distribution concentrated between 20-500 nm.

[0017] Preferably, the shellfish in step (1) is one or more of river clams, golden clams, hard clams, mussels, scallops, Arctic clams, oysters, razor clams, mixed clams, abalones, etc.

[0018] Preferably, the alcohol used in step (1) is one or a combination of more than one of ethanol, DMSO, propanol and methanol.

[0019] Preferably, the concentration of the shellfish nanocrystals in the aqueous phase system in step (2) is 0.01-30%.

[0020] The volume ratio of the aqueous phase system to the oil phase system is (99-1):(1-99).

[0021] Preferably, the high-speed shearing homogenization strength is 500-50000 r / min, and the time is 0.5-30 min.

[0022] Preferably, the oil phase system is animal fat, plant lipid or mixed fat.

[0023] As preferred, the oil phase system comprises one or a combination of several of the following: algal oil, fish oil, lard, chicken oil, duck oil, mutton oil, beef oil, shrimp oil, olive oil, palm oil, soybean oil, sunflower oil, peanut oil, corn oil, sesame oil, rapeseed oil, walnut oil, vegetable (essential) oil, medium-long chain fatty acid oil, short chain fatty acid oil.

[0024] In a second aspect, the present application also provides an emulsion prepared by the above method,

[0025] The emulsion comprises any one of high internal phase Pickering emulsion, low internal phase Pickering emulsion or common emulsion;

[0026] It can tolerate 0-600 mM salt ion concentration or 121℃ temperature.

[0027] In a third aspect, the present application also provides the emulsion as described above for use in the fields of food, cosmetics and biomedicine.

[0028] The present application has the following advantages and beneficial effects relative to the prior art:

[0029] (1) The present application uses nano-crystals in the thermal extraction or thermal processing of shellfish as the emulsion interface stabilizer, which is widely available and simple to prepare, without the need for chemical modification or the introduction of chemical or food additives, and is green and safe;

[0030] (2) The interface emulsification and stabilization effect is efficient, and in addition to the effect of nano-particle interface stabilization, the surface of the selected nano-particles is also rich in amphiphilic components, making the emulsion preparation effect stable and efficient;

[0031] (3) The shellfish nano-crystals can stabilize various oils to obtain high internal phase or low internal phase emulsions, including animal oils and plant lipids;

[0032] (4) The stabilized emulsion can tolerate acid and alkali, high temperature and salt ions, and its integrity does not change significantly in an acidic environment, with a content marker release of less than 1%;

[0033] (5) The shellfish nano-crystals themselves carry components such as phytosterols and ornithine, which can reduce the risk of cardiovascular diseases of the obtained emulsion;

[0034] The above advantages greatly broaden the practical application range of shellfish nano-crystals, which can be used as a new type of nano-stabilizer for emulsion preparation. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The amphiphilic content of the nano-particles obtained by gradient extraction of different alcohols.

[0036] Figure 2 The particle size distribution of the selected shellfish nano-crystals.

[0037] Figure 3 Pickering emulsion of medium chain fatty acid oil stabilized by bivalve nanocrystals;

[0038] (A)&(B): fixed crystal concentration C=3%, oil-water ratio 2:8~8:2; (C)&(D): fixed oil-water ratio 6:4, crystal concentration 1%~5%; (E)&(F): fixed oil-water ratio 8:2, crystal concentration 1%~5%.

[0039] Figure 4 Stability of Pickering emulsion of medium chain fatty acid oil (MCT) stabilized by bivalve nanocrystals;

[0040] (A)&(B): fixed oil-water ratio 6:4, particle concentration C=3%, pH stability and ion stability; (C): emulsion under different pH and ion concentration; (D): heat sterilization stability of fixed oil-water ratio 6:4, particle concentration 1%~5%.

[0041] Figure 5 Pickering emulsion of fish oil or lard stabilized by bivalve nanocrystals.

[0042] Figure 6 Stability of Pickering emulsion of algal oil stabilized by nanoparticles under acidic pH condition. DETAILED DESCRIPTION

[0043] The present application will be further described below in conjunction with the accompanying drawings and specific examples. Those skilled in the art will be able to implement the present application based on these descriptions. In addition, the examples of the present application involved in the following description are generally only a part of the examples of the present application, not all examples. Therefore, all other examples obtained by those skilled in the art based on the examples in the present application without making creative efforts should belong to the scope of protection of the present application.

[0044] The performance tests of the bivalve nanocrystals and the emulsion involved in the present application are shown as follows.

[0045] Component content test: The content of the amphiphilic component of the bivalve nanoparticles is determined by phosphomolybdic acid ultraviolet method to screen the bivalve nanocrystals.

[0046] Particle size test: The particle size of the nanocrystals and the emulsion is determined by laser light scattering technology.

[0047] Stability test: The release amount of vitamin E content is determined under acidic environment to evaluate the stability under acidic harsh environment.

[0048] Example 1: Screening and separation of bivalve nanocrystals

[0049] The shellfish nanoparticles (major category) are obtained by using ultrafiltration separation, the ultrafiltration molecular weight cut-off is 100 kDa, and the rotation speed is 2000-5000 r / min; and different series of nanocrystals are obtained by using ethanol (10-40%) gradient sedimentation and centrifugation. Subsequently, the precipitated sample is taken, a digesting agent perchloric acid is added, digestion is performed at 180°C until transparent, cooling is performed, distilled water is added, a chromogenic agent molybdenum acid and a reducing agent (2.5% SnCl2 glycerol solution) 1 drop are added, shaking is uniformly performed, constant volume is performed, and the content is measured at 640 nm, and the method can measure the content of phospholipid and derivatives and other amphiphilic substances in the nanocrystals. The shellfish nanoparticles (sub-category) with high surface amphiphilicity are screened, and the shellfish nanocrystals rich in amphiphilic components are obtained after freeze-drying, and are stored at -20°C for standby use.

[0050] The results are shown in Figure 1 The data show that the nanocrystals obtained by 30% ethanol sedimentation have moderate amphiphilic components and the maximum absolute value of zeta potential, and therefore can be considered to have optimal electrostatic stability. High content of alcohol can competitively snatch the AC components such as phospholipid in the particles, resulting in damaged structure and reduced stability.

[0051] Figure 2 It is shown that the average particle size of the screened nanocrystals is 45.27 nm, and the PDI is 0.164, which indicates that the target shellfish nanocrystals not only have amphiphilic components, but also have small particle size and uniform distribution.

[0052] Example 2: Preparation of shellfish nanocrystal-stabilized medium-chain fatty acid oil emulsion

[0053] The shellfish nanocrystal addition amount is fixed as 1-5% by mass percentage, is dissolved in ultrapure water, and the medium-chain fatty acid oil is added in a volume ratio of oil to water from 2:8 to 8:2, and is sheared and homogenized at 15000 r / min under ice bath for 3 min to obtain a shellfish nanocrystal-stabilized medium-chain fatty acid oil emulsion, and then the droplet particle size, zeta potential of the obtained Pickering emulsion are measured, and the microstructure of the emulsion droplets is observed.

[0054] The particle size and particle size distribution of the fresh or stored emulsion prepared in the application are measured by Malvern S3500 laser particle size analyzer. The relative refractive index of the emulsion is set as 1.09, which is the ratio of the refractive index of oil (1.4499) to the refractive index of water (1.33). The particle size of the emulsion is represented by d4,3 (volume-weighted average particle size). The Pickering emulsion is diluted by 5 times, and the size and morphology of the emulsion droplets are observed by optical microscope (adjusting the objective magnification, collecting data by computer and taking pictures).

[0055] The results are shown in Figure 3As shown, the bivalve nanocrystals successfully stabilized the Pickering emulsion system of medium-chain fatty acid oil, with d4,3 particle size from 24.1 ± 0.7 to 48.6 ± 1.9 μm, and the droplets of both high and low internal phase emulsions were spherical.

[0056] Meanwhile, Figure 4 It is shown that the Pickering emulsion prepared by the present application is relatively stable under pH 3-11, NaCl concentration of 0-600 mM, and heat sterilization treatment at different temperatures.

[0057] Example 3: Preparation of lard or fish oil emulsion stabilized by bivalve nanocrystals

[0058]

Lard Pickering emulsion system stabilized by bivalve nanocrystals

[0059] The amount of bivalve nanocrystals added was fixed at 3% by mass, dissolved in ultrapure water, the water bath temperature was controlled at 4°C, lard was added according to a volume ratio of oil to water of 7:3 (preheated and melted), and shearing homogenization was performed at 20000 r / min for 1 min. The particle size of the obtained Pickering emulsion droplets was measured and the microstructure of the emulsion droplets was observed.

[0060] The particle size and particle size distribution of the fresh or stored emulsion prepared by the present application were measured using a Malvern S3500 laser particle size analyzer. The relative refractive index of the emulsion was set to 1.096, which is the ratio of the refractive index of oil (1.4589) to the refractive index of water (1.33). The particle size of the emulsion was expressed as d4,3 (volume-weighted average particle size). The Pickering emulsion was diluted 10 times, and the size and morphology of the emulsion droplets were observed using an optical microscope (adjusting the magnification of the objective lens, collecting data by computer and taking pictures).

[0061] The results are shown in Table 1. Figure 5 As shown, the d4,3 particle size of the lard Pickering emulsion system stabilized by bivalve nanocrystals was 279.2 ± 37.3 μm, and the droplets were spherical.

[0062]

Fish oil Pickering emulsion system stabilized by bivalve nanocrystals

[0063] The amount of bivalve nanocrystals added was fixed at 3% by mass, dissolved in ultrapure water, the water bath temperature was controlled at 4°C, fish oil was added according to a volume ratio of oil to water of 7:3, and shearing homogenization was performed at 20000 r / min for 1 min. The particle size of the obtained Pickering emulsion droplets was measured and the microstructure of the emulsion droplets was observed.

[0064] The particle size and particle size distribution of the fresh or stored emulsion prepared by the present application were measured by Malvern S3500 laser particle size analyzer. The relative refractive index of the emulsion was set to 1.096, which was the ratio of the refractive index of oil (1.4589) to the refractive index of water (1.33). The particle size of the emulsion was expressed as d4,3(volume weighted average particle size). The Pickering emulsion was diluted 10 times, and the size and morphology of the emulsion droplets were observed by optical microscope (adjusting the objective lens magnification, collecting data by computer and taking pictures).

[0065] The results are shown in Table 1. Figure 5 As shown in Table 1, the d4,3particle size of the shell nanocrystal-stabilized fish oil Pickering emulsion system was 48.3±1.2μm, and the droplets were spherical.

[0066] Example 4: Preparation of shell nanocrystal-stabilized algal oil emulsion and its stability

[0067] Vitamin E was added to the algal oil to adjust the concentration to 5% (volume fraction of oil phase). Then the algal oil was added to the shell nanocrystal solution, and homogenized at 20000 r / min under ice bath for 1 min to form an emulsion (oil phase accounted for 60%).

[0068] The particle size and particle size distribution of the fresh or stored emulsion prepared by the present application were measured by Malvern S3500 laser particle size analyzer. The relative refractive index of the emulsion was set to 1.096, which was the ratio of the refractive index of oil (1.4589) to the refractive index of water (1.33). The particle size of the emulsion was expressed as d4,3(volume weighted average particle size). The Pickering emulsion was diluted 10 times, and the size and morphology of the emulsion droplets were observed by optical microscope (adjusting the objective lens magnification, collecting data by computer and taking pictures).

[0069] Results Figure 6 As shown in Table 1, the d4,3particle size of the shell nanocrystal-stabilized fish oil Pickering emulsion system was 48.3±1.2μm, and the droplets were spherical.

[0070] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, which are all included in the protection scope of the present application.

Claims

1. A method for preparing a highly efficient and stable emulsion based on shellfish nanocrystals, characterized by, The method comprises the following steps: (1) The bivalve nano-particles obtained by ultrafiltration separation are subjected to ethanol gradient sedimentation to obtain bivalve nano-particles with high surface amphiphilicity and concentrated particle size distribution, which are freeze-dried to obtain bivalve nano-crystals; (2) The bivalve nano-crystals are dissolved in distilled water or buffer solution to obtain an aqueous phase system, which is homogenized with an oil phase system to obtain the high-efficiency and stable emulsion based on bivalve nano-crystals; In the step (1), the bivalve nano-particles are obtained by heating bivalve in hot water at 80-120℃ for 10-200 min, centrifugal ultrafiltration with a molecular weight cut-off of 10-300 KDa, to obtain bivalve nano-particles with high surface amphiphilicity and concentrated particle size distribution with an average particle size of 20-500 nm; The content determination method of amphiphilic substances is based on phosphomolybdic acid ultraviolet method. The precipitate sample is taken, and a digesting agent of perchloric acid is added. The sample is digested to transparency at 180℃, cooled, added with distilled water, and added with a color developing agent of molybdenum sulfate and a reducing agent of 2.5% SnCl2 glycerol solution. The sample is shaken, and the content of amphiphilic substances in the nano-crystals is determined at 640 nm. The amphiphilic substances include phospholipids and derivatives.

2. The method according to claim 1, wherein the bivalve in the step (1) is one or more of Corbicula fluminea, Meretrix meretrix, Mytilus edulis, Chlamys farreri, Arctic shell, Oyster, Littleneck, mixed clam, and abalone.

3. The method according to claim 1, wherein the concentration of the bivalve nano-crystals in the aqueous phase system in the step (2) is 0.01-30%.

4. The method according to claim 1 or 3, wherein the homogenization intensity is 500-50000 r / min, and the time is 0.5-30 min.

5. The method according to claim 1 or 3, wherein the oil phase system comprises one or a combination of several of algal oil, fish oil, lard, chicken oil, duck oil, mutton oil, beef oil, shrimp oil, olive oil, palm oil, soybean oil, sunflower seed oil, peanut oil, corn oil, sesame oil, rapeseed oil, walnut oil, and plant essential oil.

6. The emulsion prepared by the method of any one of claims 1-5, wherein the emulsion comprises any one of high internal phase Pickering emulsion, low internal phase Pickering emulsion, or ordinary emulsion.

7. The emulsion of claim 6 for use in food and cosmetic fields. ​ ​ ​ ​ ​ ​ ​

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