Preparation method and application of novel large-size Pickering emulsion
阅读说明：本技术 一种新型大尺寸皮克林乳液的制备方法及应用 (Preparation method and application of novel large-size Pickering emulsion ) 是由 方亚鹏 胡冰 麻瑞祥 韩玲钰 于 2019-10-06 设计创作，主要内容包括：本发明公开了一种新型大尺寸皮克林乳液的制备方法,属于皮克林乳液制备技术领域。本发明选用不同种类淀粉制备的壳核结构淀粉,然后将此类淀粉作为乳化剂加入到油水混合液中,通过调控油脂密度、油脂含量、乳化剂浓度、剪切速率等,使皮克林乳液达到不同粒径并且可以在高含油量(70%含油量)时长时间稳定。另外本发明可以省去乳液制作时所必须的剪切步骤,仅通过手摇晃含有壳核结构淀粉的油水混合液,即可在短时间内形成稳定的皮克林乳液。本发明所使用的材料全部为天然可食用材料,制备方法简单,形成的皮克林乳液能够长时间稳定,可用于新型口感食品,如即食沙拉汁、蛋黄酱的制备。(The invention discloses a preparation method of a novel large-size pickering emulsion, and belongs to the technical field of pickering emulsion preparation. The invention selects the starch with a core-shell structure prepared by different types of starch, then the starch is used as an emulsifier to be added into the oil-water mixed solution, and the Pickering emulsion can reach different particle sizes and can be stable for a long time at high oil content (70% oil content) by regulating and controlling the oil density, the oil content, the emulsifier concentration, the shearing rate and the like. In addition, the invention can save the shearing step required in the preparation of the emulsion, and can form stable pickering emulsion in a short time only by shaking the oil-water mixed solution containing the starch with the shell-core structure by hand. The materials used in the invention are all natural edible materials, the preparation method is simple, the formed pickering emulsion can be stable for a long time, and the pickering emulsion can be used for preparing novel mouthfeel foods, such as instant salad juice and mayonnaise.)
1. A preparation method of novel large-size Pickering emulsion is characterized by comprising the following steps: the pickering emulsion takes starch with a shell-core structure as a stable emulsifier, mixed oil of medium-chain triglyceride and sucrose acetate isobutyrate as an oil phase, and deionized water as a water phase, and the preparation method comprises the following steps:
(1) preparation of a sample solution: preparing ethanol-water solution, continuously preparing zein solution with the ethanol-water solution, shaking up, placing in a water bath ultrasonic device, and performing ultrasonic treatment for 15min to obtain a solution for later use; preparing an OSA starch solution, magnetically stirring for 2 hours, and standing for later use; preparing sucrose acetate isobutyrate-medium chain triglyceride (SAIB-MCT) mixed oil, wherein the mixing volume ratio of the medium chain triglyceride to the sucrose acetate isobutyrate is 3:2, and after mixing, placing the mixture in a water bath at 70 ℃ and stirring the mixture for 2 hours at constant temperature to uniformly mix the mixture;
(2) preparing a core-shell structure starch emulsifier: adding starch into a zein solution, placing the zein solution on a magnetic stirrer for stirring at 200-400rpm, and simultaneously dropping an OSA starch solution at a constant speed to reduce the concentration of ethanol in the solution so as to separate out zein, and forming a shell layer on the surface of a starch particle by self-assembly to finally form starch particles with a shell-core structure of starch-zein; standing for precipitation, repeatedly washing with water for 3-4 times, removing residual ethanol and zein particles in the solution, and freeze drying;
(3) preparation of pickering emulsion: preparing the oil phase and the water phase in the step (1) into an oil-water mixed solution, adding the starch with the shell-core structure in the step (2), shearing the mixture for 20 to 30 seconds by using a high-speed shearing instrument at a shearing rate of 5000rpm/min to 20000rm/min, and standing to finally form the large-size Pickering emulsion taking the starch with the shell-core structure as an emulsifier.
2. The method of claim 1 for preparing a novel large size pickering emulsion, wherein: the ethanol-water solution of zein in the step (1), wherein the volume concentration of ethanol is 70%, and the mass concentration of zein is 1.0-3.0%; the mass concentration of the OSA starch is 1-3%, preferably 2%.
3. A method for preparing a novel large size pickering emulsion according to claim 1, wherein the volume concentration of ethanol in the ethanol-water solution in step (2) is reduced from 70% to 30%, preferably 45%.
4. The method of claim 1 for preparing a novel large size pickering emulsion, wherein: the mass content of the starch added into the zein solution in the step (2) is 2.5% w/w-7.5%, and the starch is preferably 4.5%.
5. The method of claim 1 for preparing a novel large size pickering emulsion, wherein: the dropping rate of the OSA starch solution in the step (2) is controlled to be 0.1-0.5ml/min, and preferably 0.2 ml/min.
6. The method of claim 1 for preparing a novel large size pickering emulsion, wherein: the mass content of SAIB in the mixed oil phase prepared in the step (3) is 20% -50%, and preferably 40%.
7. The method of claim 1 for preparing a novel large size pickering emulsion, wherein: the amount of the starch with the shell-core structure added in the step (3) is 1-5% of the mass of the oil-water mixed solution, and is preferably 3%.
8. The method of claim 1 for preparing a novel large size pickering emulsion, wherein: the mixing volume ratio of the oil phase and the water phase in the step (3) is 10-70%, preferably 50-60%.
9. The method of claim 1 for preparing a novel large size pickering emulsion, wherein: the shear rate in said step (3) is 5000rpm/min, preferably 30 s.
10. The application of the novel large-size Pickering emulsion is characterized in that: the Pickering emulsion can be used for preparing food-grade salad juice and food-grade mayonnaise.
Technical Field
The invention relates to the technical field of Pickering emulsion preparation, in particular to a preparation method and application of large-size Pickering emulsion based on core-shell structure starch.
Background
Many of the processed foods we prefer, personal care products to moisturize and beautify the skin, agricultural chemical products to protect crops, and pharmaceutical preparations we rely on are made based on emulsions. Emulsions can exist in either oil-in-water or water-in-oil form, but in both cases very stable droplets are required to prevent breaking of the emulsion leading to deterioration of the product. The stabilization of emulsion droplets is usually achieved by the addition of amphiphilic molecules (such as surfactants or emulsifiers) which act by lowering the interfacial tension between the phases, increasing steric hindrance or electrostatic repulsion between the droplets. In addition to small molecular weight surfactants, soluble proteins and polymeric emulsifiers, solid particles with double wettability can be used to stabilize emulsions, which are named Pickering emulsions (Pickering). Since its discovery by human in 1903, it has been widely used in various fields such as food, medicine, cosmetics, etc. The type, ratio of oil and water phases combined with the particles having dual wetting properties gives the Pickering emulsion many of the formulation characteristics of practical value and the ability to produce highly stable droplets. The types of particles currently in common use include inorganic or synthetic particles such as silica, alumina, titanium oxide, latex, clay, and the like, but they are not used in the food industry. Therefore, finding some natural food particles or making particles that have double wettability and are capable of stabilizing pickering emulsions using food materials entirely has been a difficult problem in the food industry.
On the other hand, the particles in a pickering emulsion need to do some work if they move from the equilibrium position of the interface to either volume phase. When it is completely out of the interface, there are many large variations in the surface free energy of the system. The free energy of desorption for a 10 nm particle leaving the interface is several thousand kT, compared to only 10kT for a surfactant of similar particle size. The stability of pickering emulsions is much higher than that of conventional emulsions. Whereas the separation of a single particle can be linearly increased with respect to its radius squared. Thus, particles with larger particle sizes are more difficult to stabilize the pickering emulsion, and once it is successfully stabilized, its stability will be better than that of smaller particle sizes.
The chemical formula of the starch is C6H12O6Is formed by polymerizing glucose molecules. It is the most common storage form of carbohydrates in cells and one of the most important sources of energy for humans. Native starch is not hydrophobic in nature, but its hydrophobicity can be increased by chemical modification and coating with a hydrophobic shell, and its double wettability is increased. Zein (zein) is a protein which is extracted from corn for the first time in 1821 by Gorhamin and can be dissolved in ethanol, has good film forming property, adhesiveness, water resistance and moisture resistance, has the characteristics of acid resistance, oil resistance and the like, and can be widely applied to other industries such as medicine, food, chemical industry and the like. In the food industry, the alcohol soluble protein can be used as a coating agent, namely a coating is formed on the surface of food in a spraying mode, and the coating can prevent moisture and oxidation, thereby prolonging the shelf life of the food, and can also increase the luster when being sprayed on fruits. Sucrose acetate isobutyrate is a stabilizer and a relative density regulator, has certain viscosity, and can increase the density of grease after being mixed with the grease.
The method modifies common starch by using octenyl succinic anhydride soluble modified starch (OSA starch), separates out zein by an anti-solvent method, and forms a starch-zein core-shell structure on the surface of starch granules in a self-assembly manner, and the starch with the core-shell structure and the grease with well-mixed density are used for preparing Pickering emulsion.
The invention content is as follows:
the invention aims to solve the technical problem of providing a preparation method of a large-size Pickering emulsion stabilized by starch with a shell-core structure, so that the large-size Pickering emulsion has a larger structure than the traditional Pickering emulsion and has better stability under the normal temperature condition, and the method is suitable for most of the conventional oil on the market.
The inventors continuously make efforts to finally obtain a preparation method of a novel large-size Pickering emulsion, which takes starch with a shell-core structure as a stable emulsifier, takes mixed oil of medium-chain triglyceride and sucrose acetate isobutyrate as an oil phase and deionized water as a water phase, and the preparation method comprises the following steps:
(1) preparation of a sample solution: preparing ethanol-water solution, continuously preparing zein solution with the ethanol-water solution, shaking up, placing in a water bath ultrasonic device, and performing ultrasonic treatment for 15min to obtain a solution for later use; preparing an OSA starch solution with a certain concentration, magnetically stirring for 2 hours, and standing for later use; preparing sucrose acetate isobutyrate-medium chain triglyceride (SAIB-MCT) mixed oil, wherein the mixing volume ratio of the medium chain triglyceride to the sucrose acetate isobutyrate is 3:2, and after mixing, placing the mixture in a water bath at 70 ℃ and stirring the mixture for 2 hours at constant temperature to uniformly mix the mixture;
(2) preparing a core-shell structure starch emulsifier: adding starch into a zein solution, placing the zein solution on a magnetic stirrer for stirring at 200-400rpm, and simultaneously dropping an OSA starch solution at a constant speed to reduce the concentration of ethanol in the solution so as to separate out zein, and forming a shell layer on the surface of a starch particle by self-assembly to finally form starch particles with a shell-core structure of starch-zein; standing for precipitation, repeatedly washing with water for 3-4 times, removing residual ethanol and zein particles in the solution, and freeze drying;
(3) preparation of pickering emulsion: preparing the oil phase and the water phase in the step (1) into an oil-water mixed solution, adding the starch with the shell-core structure in the step (2), shearing the mixture for 30s by using a high-speed shearing instrument, wherein the shearing rate is 5000rpm/min-20000rm/min, and standing the mixture to finally form the large-size Pickering emulsion taking the starch with the shell-core structure as an emulsifier.
Preferably, in the preparation method of the novel large-size pickering emulsion, the ethanol-water solution of zein in the step (1) has a volume concentration of 70% and a mass concentration of zein of 1.0-3.0%.
Preferably, in the preparation method of the novel large-size pickering emulsion, the mass concentration of the OSA starch in the OSA starch solution in the step (1) is 1-3%, preferably 2%.
Preferably, in the preparation method of the novel large-size pickering emulsion, the volume concentration of ethanol in the ethanol-water solution in the step (2) is reduced from 70% to 30%, preferably 45%.
Preferably, in the method for preparing the novel large-size pickering emulsion, the mass content of the starch added into the zein solution in the step (2) is 2.5% w/w-7.5%, preferably 4.5%.
Preferably, in the preparation method of the novel large-size Pickering emulsion, as described above, the adding rate of the OSA starch solution in the step (2) is controlled to be 0.1-0.5ml/min, preferably 0.2 ml/min.
Preferably, in the preparation method of the novel large-size pickering emulsion, the SAIB content in the mixed oil phase prepared in the step (3) is 20% -50%, preferably 40%.
Preferably, in the preparation method of the novel large-size pickering emulsion, the added core-shell structure starch in the step (3) accounts for 1% -5%, preferably 3% of the mass of the oil-water mixed solution.
Preferably, in the method for preparing the novel large-size pickering emulsion, as described above, the mixing volume ratio of the oil phase and the water phase in the step (3) is 10-70%, preferably 50-60%.
Preferably, the shear rate in step (3) is 5000rpm/min, and the time is preferably 30 s.
Preferably, the preparation method of the novel large-size pickering emulsion comprises the steps of preparing the starch with the shell-core structure from wheat starch, corn starch, waxy corn starch, cassava starch, potato starch and rice starch.
The application of the novel large-size Pickering emulsion comprises the following steps: the Pickering emulsion can be used for preparing food-grade salad juice, and can be used for preparing products such as food-grade mayonnaise and the like after heating and pasting.
Compared with the prior art, the invention has the advantages that:
1. the invention uses the starch with a shell-core structure prepared by an anti-solvent method as an emulsifier, and has the advantages of simple and easy method, low preparation components and food-grade materials.
2. The size of the Pickering emulsion can be effectively regulated and controlled by simply changing the content of the starch with the shell-core structure, the shearing rate and the proportion of oil and water phases.
3. The prepared Pickering emulsion can be stable for a long time at normal temperature and other severe environments, and can be used for packaging sensitive bioactive components in foods and local formulas, and making portable mayonnaise or salad juice.
4. The core-shell structure starch granules have good surface activity and double wettability, can form Pickering emulsion with high grease content, can form large-size Pickering emulsion of hundreds of microns or even millimeter level, can be used for preparing novel mouthfeel food such as instant salad juice and mayonnaise, and has excellent stability, packaging performance and freeze-thaw stability which prove to be suitable for packaging sensitive bioactive components in food and local formulas and the like.
5. The core-shell structure starch granules have good surface activity, can form large-granule Pickering emulsion by simple manual shaking, can be used for preparing food-grade salad juice, and can be used for preparing products such as food-grade mayonnaise and the like after being heated and gelatinized.
Drawings
FIG. 1 is a picture of a core-shell structure starch emulsifier product prepared from corn starch by an anti-solvent method.
FIG. 2 is a microscope photograph of Pickering granules formed by core-shell structure granules of corn starch, potato starch, tapioca starch, wheat starch, waxy corn starch and rice starch at 5000rpm for 30s, respectively, wherein the oil phase content is 50%.
FIG. 3 is a fluorescent microscope photograph of Pickering granules formed by core-shell structure granules of corn starch, potato starch, tapioca starch, wheat starch, waxy corn starch and rice starch at 5000rpm for 30s, respectively, with the oil phase content being 50%.
FIG. 4 is a laser confocal microscope photograph of Pickering granules formed by core-shell structure granules of corn starch, potato starch, tapioca starch, wheat starch, waxy corn starch and rice starch at 5000rpm for 30s, wherein the oil phase content is 50%.
FIG. 5 shows scanning electron micrographs of Pickering granules formed from core-shell structure granules of corn starch, potato starch, tapioca starch, wheat starch, waxy corn starch and rice starch at 5000rpm for 30s, respectively, with the oil phase content being 30%.
FIG. 6 is a photograph of the three-phase contact angles of corn starch, potato starch, tapioca starch, wheat starch, waxy corn starch and rice starch, respectively, and core-shell structured particles thereof.
FIG. 7 shows Pickering emulsions prepared with different emulsifier (cassava core-shell structure starch) concentrations at a fixed rotation speed of 10000rpm and a fixed oil phase concentration of 30%, wherein the emulsifier concentrations are respectively 1%, 2%, 3% and 4%.
FIG. 8 shows Pickering emulsions prepared at different rotation speeds after the concentration of the fixed emulsifier (cassava core-shell structure starch) is 3% and the concentration of the fixed oil phase is 30%, wherein the rotation speeds are respectively 5000rpm, 10000rpm, 15000rpm, 20000rpm and 25000 rpm.
FIG. 9 shows Pickering emulsions prepared at different oil phase concentrations with a fixed rotation speed of 10000rpm and a fixed emulsifier (cassava core-shell structure starch) concentration of 3%, wherein the oil phase concentrations are respectively selected from 30%, 40%, 50% and 60%. 70 percent.
FIG. 10 is a Pickering emulsion made by shaking by hand for 5 seconds using 2% and 3% tapioca kernel structure starch and 50% oil phase.
The specific implementation mode is as follows:
in order to clearly illustrate the technical features of the scheme of the invention, the invention is explained below with reference to specific embodiments. The scope of protection of the invention is not limited to these examples. All changes, modifications and equivalents that do not depart from the spirit of the invention are intended to be included within the scope thereof.
The starch of the present invention is not limited to corn starch, potato starch, tapioca starch, wheat starch, waxy corn starch, rice starch, and other common starches.
The choice of oil in the present invention is not limited to medium chain triglycerides, and other common oils are suitable for use in the present invention, such as soybean oil, peanut oil, rapeseed oil, and the like.
In particular, the choice of the emulsification process of the present invention is not limited to the use of high shear, and large-size pickering emulsions can also be formed by simple manual shaking.