Preparation method of canna edulis esterified starch and Pickering emulsion with stable esterified starch nanocrystals

Abstract

The invention discloses a preparation method of taro esterified starch and esterified starch nanocrystal stabilized Pickering emulsion, which comprises the following steps: mixing and stirring taro starch and a sulfuric acid solution, precipitating and drying to obtain SNCs powder; reacting the canna starch and the distilled water dispersion liquid of the SNCs for a certain time under different pH values, and drying and precipitating to obtain OS-starch and OS-SNCs; mCT is added into the dispersion liquid containing the OS-starch and the OS-SNCs to be homogenized, and the Pickering emulsion with the stable OS-starch and the Pickering emulsion with the stable OS-SNCs are obtained. The canna edulis esterified starch and the Pickering emulsion with stable esterified starch nanocrystals, which are prepared by the preparation method provided by the invention, have uniform liquid drop size, good stability and pseudoplastic fluid behavior; the compound has good carrier performance and slow release effect on bioactive compounds, also shows good intestinal flora regulation ability, and can be applied to transportation of bioactive substances and novel prebiotic food. The preparation method is simple and easy to operate, green and environment-friendly, and the raw materials and products are safe and non-toxic and have no potential safety hazard.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of banana and taro starch-based stabilized Pickering emulsions, in particular to a preparation method of banana and taro esterified starch and esterified starch nanocrystal-stabilized Pickering emulsions. Background Art

[0002] Pickering emulsion is a new type of emulsion that uses ultrafine solid particles or solid colloidal particles instead of traditional surfactants as emulsifiers. These colloidal particles can adsorb on the water-oil interface to form a dense film, giving the emulsion excellent stability. Starch is a natural and renewable macromolecular carbohydrate that has attracted widespread attention in stabilizing Pickering emulsions due to its green source, low price, safety and non-toxicity. At the same time, starch nanocrystals (SNCs) prepared by sulfuric acid hydrolysis have attracted great interest due to their small nanosize and unique disc morphology, making them ideal candidates for stabilizing Pickering emulsions. However, since natural starch and SNCs are hydrophilic, octenyl succinic anhydride (OSA) modification is usually used to improve their emulsification efficiency.

[0003] Previous studies have found that liquid forms of drugs lead to rapid absorption and greater bioavailability. Therefore, preparing drugs in the form of emulsions can improve their therapeutic effects. Curcumin is a natural polyphenolic compound isolated from turmeric with antioxidant, anticancer and antibacterial properties. However, curcumin faces challenges such as strong hydrophobicity, easy photolysis, instability in the alkaline environment of the intestine and low bioavailability, which greatly limits its application range. Therefore, we chose curcumin as a model drug to evaluate the carrier properties of Pickering emulsions stabilized by esterified starch (OS-starch) and esterified starch nanocrystals (OS-SNCs).

[0004] Resistant starch (RS) and its nanoparticles are fermented by the microbiota in the colon to produce short-chain fatty acids (SCFAs) with potential health benefits. These RS have been shown to exhibit prebiotic effects in humans, however, the controlled release properties of bioactive compounds in Pickering emulsion systems remain to be investigated, as well as their effects on the intestinal microbiota.

[0005] The starch from the herb Canna edulis of the Cannaceae family has large particles, dense starch gel structure, and high amylose content. It is an ideal material for the preparation of Pickering emulsions stabilized by esterified starch and esterified starch nanocrystals. There are currently no related reports, and its preparation method deserves further study. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals, so as to provide a method for preparing a Pickering emulsion with simple preparation method, no potential safety hazard, high emulsification efficiency and good emulsion stability, so that the prepared Pickering emulsion can provide a safe and effective carrier for the transport and sustained release of biologically active substances in the body.

[0007] To achieve the above object, the present invention provides a method for preparing a Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals, the steps of which are as follows:

[0008] S1. Preparation of SNCs: adding a certain amount of sulfuric acid solution to a certain amount of banana and taro starch, stirring and mixing to obtain a starch dispersion, stirring the starch dispersion for 5-6 days and then centrifuging to obtain a precipitate, washing the precipitate with distilled water for 2-3 times, and freeze-drying the precipitate to obtain SNCs powder;

[0009] S2, preparing OS-starch and OS-SNCs, respectively weighing a certain amount of banana taro starch and the SNCs powder prepared in step S1, dispersing them in distilled water, adjusting the pH to 8.0-9.5, slowly dripping OSA, stirring while dripping, and maintaining the pH at 8.0-9.5. After reacting for 2 hours, adjusting the pH of the reaction mixture to 6.0-7.0, centrifuging to remove the supernatant, washing the precipitate with distilled water 2-3 times, and drying the precipitate to obtain OS-starch and OS-SNCs;

[0010] S3. Preparing Pickering emulsions stabilized by OS-starch and OS-SNCs. Weigh a certain amount of OS-starch prepared in step S2 and OS-SNCs prepared in step S3, respectively, and disperse them in distilled water to obtain OS-starch dispersion and OS-SNCs dispersion. Add MCT to the above dispersions, respectively, and homogenize for 3 minutes to obtain OS-starch stabilized Pickering emulsions and OS-SNCs stabilized Pickering emulsions.

[0011] Preferably, the concentration of the sulfuric acid solution in step S1 is 3.16 mol / L, and the banana and taro starch accounts for 10%-40% of the total mass of the starch dispersion; the stirring speed of the starch dispersion is 400 rpm / min, and the stirring temperature is 35°C; the centrifugation conditions are: centrifugation at a speed of 4000 rpm / min for 10 min.

[0012] Preferably, in step S2, the banana and taro starch and SNCs powder each account for 20%-50% of the total mass of the starch dispersion; and OSA accounts for 3% of the mass of the banana and taro dry starch and SNCs powder.

[0013] Preferably, the temperature of the distilled water in step S2 is 30-40°C, and the slow dripping of OSA means that all OSA used is dripped within 1 hour; and the drying temperature of the precipitate is 40°C.

[0014] Preferably, in step S4, OS-starch and OS-SNCs each account for 2%-5% of the total mass of the dispersion, the amount of MCT added is 20%-80% of the total mass of the dispersion, and the homogenization speed is 13000 rpm / min.

[0015] Preferably, the pH is adjusted by NaOH and HCl.

[0016] A Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals prepared by the preparation method as described above.

[0017] Application of banana-taro esterified starch and Pickering emulsion stabilized by esterified starch nanocrystals prepared by the preparation method described above in encapsulating food and medicine.

[0018] The invention discloses an application of banana-taro esterified starch and Pickering emulsion stabilized by esterified starch nanocrystals prepared by the preparation method as a functional excipient in the fields of traditional Chinese medicine extract, probiotic embedding and cosmetics.

[0019] Therefore, the preparation method of banana and taro esterified starch and esterified starch nanocrystal-stabilized Pickering emulsion provided by the present invention has the following specific technical effects:

[0020] (1) The Pickering emulsion stabilized by the banana-taro esterified starch and esterified starch nanocrystals prepared by the preparation method provided by the present invention has uniform droplet size and good stability, and exhibits pseudoplastic fluid behavior;

[0021] (2) The Pickering emulsion stabilized by the banana-taro esterified starch and esterified starch nanocrystals prepared by the preparation method provided by the present invention exhibits good carrier performance and sustained release effect for bioactive compounds, and also exhibits good intestinal flora regulation ability, and can be applied to the transportation of bioactive substances and novel prebiotic foods;

[0022] (3) The method for preparing the Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals provided by the present invention is simple and easy to operate, does not require high temperature and high pressure, has low requirements for instruments and equipment, and both the raw materials and products are safe and non-toxic. There is no emission of toxic and harmful substances during the preparation process, which is green and environmentally friendly and has no safety hazards.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0025] Figure 1 It is the scanning electron microscope result of the effect test (I) in the embodiment of the present invention, wherein part A is the scanning electron microscope picture of banana-taro starch, part B is the scanning electron microscope picture of OS-starch, part C is the scanning electron microscope picture of SNCs, and part D is the scanning electron microscope picture of OS-SNCs;

[0026] Figure 2 The infrared spectrum results of the effect test (I) in the embodiment of the present invention are shown in FIG. 1 , wherein part A is the 1H NMR spectrum; part B is the FT-IR result; part C is the XRD result; and part D is the contact angle measurement result;

[0027] Figure 3 This is the characterization result of the Pickering emulsion stabilized by banana-taro esterified starch and esterified starch nanocrystals in the effect test (II) of the embodiment of the present invention, wherein Part A is the Pickering emulsion stabilized by 3.0wt% OS-starch; Part B is the Pickering emulsion stabilized by 3.0wt% OS-SNCs; Part A1 is the microstructure of the Pickering emulsion stabilized by OS-starch, and Part B1 is the microstructure of the Pickering emulsion stabilized by OS-SNCs, and the scale bars of Part A1 and Part B1 are both 100μm;

[0028] Figure 4 These are the results of simulated gastrointestinal digestion of the curcumin-loaded banana and taro esterified starch and esterified starch nanocrystal-stabilized Pickering emulsions in the effect test (III) of the embodiments of the present invention, wherein Part A is the release rate of curcumin during digestion in the curcumin-loaded Pickering emulsions stabilized by OS-starch and OS-SNCs; and Part B is the stability of curcumin in the Pickering emulsions stabilized by OS-starch and OS-SNCs. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0030] In order to make the purpose, technical scheme and advantages of the present application clearer, more thorough and more complete, the technical scheme of the present invention is clearly and completely described below through the accompanying drawings and examples. The following detailed descriptions are all descriptions of the embodiments, and are intended to provide further detailed descriptions of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present application belongs.

[0031] The reagents and instruments used in the examples were obtained from commercial sources.

[0032] Embodiment 1

[0033] The Pickering emulsions stabilized by esterified banana starch (OS-starch) and esterified starch nanocrystals (OS-SNCs) were prepared as follows:

[0034] S1. Prepare starch nanocrystals (SNCs). Accurately weigh 30g of banana and taro starch, add 100mL of 3.16 mol / L sulfuric acid solution, stir and mix to obtain starch dispersion, stir the starch dispersion at 400rpm / min for 5 days at 35°C, centrifuge at 4000rpm / min for 10min, and take the precipitate. Add 30mL of distilled water to suspend the precipitate, then centrifuge at 4000rpm / min for 10min, repeat the steps of adding distilled water-suspension-centrifugation once, and freeze-dry the obtained precipitate to obtain SNCs powder.

[0035] S2, prepare OS-starch, weigh 30g banana taro starch, disperse it in 100mL 35 ℃ distilled water, adjust pH to 8.0 with 1M NaOH and HCl, slowly drip 1mL OSA (molecular mass is 210.27), drip and stir, keep pH at 8.0-9.5 during, react 2h and adjust pH of reaction mixture to 6.0, centrifuge at 4000rpm / min for 10min, remove supernatant. Add 30mL distilled water to precipitate, then centrifuge at 4000rpm / min for 10min, repeat distilled water-suspension-centrifugation steps 2 times, dry the precipitate obtained at 40 ℃ to obtain OS-starch.

[0036] S3, prepare OS-SNCs, weigh 30g of the SNCs powder prepared in step S1, disperse it in 100mL of 35°C distilled water, adjust the pH to 8.0, slowly drip 1mL of OSA (molecular mass 210.27), stir while dripping, keep the pH at 8.0, adjust the pH of the reaction mixture to 6.0 after 2h of reaction, centrifuge at 4000rpm / min for 10min, and remove the supernatant. Add 30mL of distilled water to the precipitate to suspend the precipitate, then centrifuge at 4000rpm / min for 10min, repeat the steps of adding distilled water-suspension-centrifugation twice, and dry the precipitate at 40°C to obtain OS-starch.

[0037] S4, prepare OS-starch stabilized Pickering emulsion, weigh 3g OS-starch prepared in step S2, disperse it in 100mL distilled water, and obtain OS-starch dispersion. The OS-starch dispersion and MCT ratio is (4:6) and homogenized at a speed of 13000rpm / min for 3min to obtain OS-starch stabilized Pickering emulsion.

[0038] S5. Prepare a Pickering emulsion stabilized by OS-SNCs. Take 3 g of OS-SNCs prepared in step S3 and disperse them in 100 mL of distilled water. The ratio of OS-SNCs dispersion to MCT is (4:6). Homogenize at a speed of 13000 rpm / min for 3 min to obtain a Pickering emulsion stabilized by OS-SNCs.

[0039] Embodiment 2

[0040] The Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals was prepared in the same manner as in Example 1, except that:

[0041] In step S1, the amount of banana-taro starch is 35 g, stirred for 6 days, and washed with distilled water for 3 times.

[0042] The amount of banana and cantaloupe starch added in step S2 is 35 g, the pH of the starch dispersion during the dropwise addition of OSA is 9.5, and the pH of the mixture after the reaction is adjusted to 7.0.

[0043] In step S3, the amount of SNCs added was 35 g, the amount of OSA was 3%, the pH of the starch dispersion was 9.5 during the dropwise addition of OSA, and the pH of the mixture after the reaction was adjusted to 7.0.

[0044] The amount of OS-starch added in step S4 was 3 g.

[0045] The amount of OS-SNCs added in step S5 was 3 g.

[0046] Embodiment 3

[0047] The Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals was prepared in the same manner as in Example 1, except that:

[0048] In step S1, the amount of banana-taro starch is 25 g, stirred for 6 days, and washed with distilled water 3 times;

[0049] The amount of banana-taro starch added in step S2 is 25 g, the pH of the starch dispersion during the dropwise addition of OSA is 9.0, and the pH of the mixture after the reaction is adjusted to 6.5;

[0050] The amount of SNCs added in step S3 was 25 g, and the pH of the starch dispersion during the addition of OSA was 8.5.

[0051] The amount of OS-starch added in step S4 was 3 g.

[0052] The amount of OS-SNCs added in step S5 was 3 g.

[0053] Embodiment 4

[0054] The preparation of OS-starch and OS-SNCs stabilized Pickering emulsion loaded with curcumin was done in the same manner as in Example 1, except that steps S4 and S5 were as follows:

[0055] S4, weigh 0.18mg OS-starch prepared in step S2, and disperse it in 6mL distilled water to obtain OS-starch dispersion. 9mg curcumin with a concentration of 1.5mg / mL was dissolved in 6mL medium chain glyceride (MCT), stirred and mixed, and heated at 120°C for 30min to form a transparent solution. Then 4mL of the above-mentioned MCT solution containing curcumin was added to the prepared OS-starch dispersion. The mixture was homogenized at 13000rpm for 3min to obtain a Pickering emulsion stabilized by OS-starch loaded with curcumin.

[0056] S5. Weigh 0.18 g of OS-SNCs prepared in step S3 and disperse it in 6 mL of distilled water to obtain an OS-SNCs dispersion. Dissolve 9 mg of curcumin at a concentration of 1.5 mg / mL in 6 mL of medium chain glyceride (MCT), stir and mix, and heat at 120 ° C for 30 min to form a transparent solution. Then draw 4 mL of the above-mentioned MCT solution containing curcumin and add it to the prepared OS-SNCs dispersion. Homogenize the mixture at 13000 rpm for 3 min to obtain a stable Pickering emulsion of OS-SNCs loaded with curcumin.

[0057] Embodiment 5

[0058] The blank type Pickering emulsions of OS-starch and OS-SNCs stabilized in oil-in-water were prepared in the same manner as in Example 1, except that steps S4 and S5 were as follows:

[0059] S4, weigh 0.18g of OS-starch prepared in step S2, and disperse it in 6mL of distilled water to obtain OS-starch dispersion. Then draw 4mL of MCT solution and add it to the prepared OS-starch dispersion. Homogenize the mixture at 13000rpm for 3min to obtain a Pickering emulsion of OS-starch stabilized in an oil-in-water blank type.

[0060] S5. Weigh 0.18 g of the OS-SNCs prepared in step S3 and disperse it in 6 mL of distilled water to obtain an OS-SNCs dispersion. Then, take 4 mL of the MCT solution and add it to the prepared OS-SNCs dispersion. Homogenize the mixture at 13000 rpm for 3 min to obtain an oil-in-water blank OS-SNCs stable Pickering emulsion.

[0061] Effect test

[0062] (I) Characterization of OS-starch and OS-SNCs

[0063] 10 mg of OS-starch prepared in step S2 of Example 1 was taken respectively, adhered to the conductive adhesive, and gold was sprayed for 45 s using a SC7620 sputtering coating instrument (Quorum, UK) at a gold spraying rate of 10 mA. Subsequently, a Gemini SEM 300 (Zeiss, Germany) scanning electron microscope was used for photography. 10 g of OS-SNCs prepared in step S3, SNCs prepared in step S1, and banana starch were taken respectively, treated in the same manner as above, and photographed using a scanning electron microscope. The results are shown in Figure 1 ,in Figure 1 Part A is the SEM photo of banana-taro starch, Part B is the SEM photo of OS-starch, Part C is the SEM photo of SNCs, and Part D is the SEM photo of OS-SNCs.

[0064] 1 mg OS-starch and 100 mg NaBr were placed in a mortar, ground thoroughly, and compressed into tablets. Nicolet™ iS20 (Thermo Scientific, USA) was used to analyze the OS-starch at 400-4000 cm -1 The infrared spectra of the samples collected at 20 °C were obtained. The treatment method of OS-SNCs was exactly the same as that of OS-starch. The results are shown in Figure 2 Part B.

[0065] In the diffraction angle range of 5-40°, the-1 The crystal morphology of OS-starch and OS-SNCs was detected at a scanning rate of 1.5 Å (Rigaku Ultima IV, Japan). The results are shown in Figure 2 Part C.

[0066] Another 100 mg of OS-starch was pressed into a shaped sheet and placed on the DSA25 (KRUSS, Germany) contact angle test platform. The equipment uses a distilled water automatic titration system to take test photos and measure contact angles. The treatment method of OS-SNCs is exactly the same as that of OS-starch. The results are shown in Figure 2 , where Part A is the nuclear magnetic resonance hydrogen spectrum (1H NMR spectrum); Part B is the Fourier transform infrared spectroscopy (FT-IR) results; Part C is the X-ray diffraction (XRD) results; and Part D is the contact angle measurement results.

[0067] (II) Characterization of Pickering emulsions stabilized by esterified banana and taro starch and esterified starch nanocrystals

[0068] We used an optical microscope (Nikon Eclipse Ts2R, Japan) to observe the microstructure of the emulsion samples with different MCT ratios (20%-80%) at room temperature.

[0069] (III) Simulated gastrointestinal digestion of curcumin-loaded banana-taro esterified starch and Pickering emulsion stabilized by esterified starch nanocrystals

[0070] Simulated gastric fluid (SGF) was prepared by mixing 2.0 g NaCl and 7 mL HCl in 1 L water. In addition, the pH of the Pickering emulsion and SGF was adjusted to 1.2 using 1 M HCl and 1 M NaOH solutions, and 0.032 g pepsin / mL was added. Next, 9 mL of the Pickering emulsion sample was mixed with 1 mL of SGF containing pepsin and placed in a dialysis bag.

[0071] The dialysis bag was placed in a 1L SGF culture bottle and incubated in a thermostatic oscillator at 37°C and 100 rpm / min for 2 hours to simulate gastric digestion. After SGF digestion, the Pickering emulsion was mixed with simulated intestinal fluid (SIF), which was prepared by mixing 6.8 mg / mL KH2PO4 and 10 mg / mL trypsin. The pH of the Pickering emulsion sample and SGF was adjusted to 6.8 with 1M HCl and 1M NaOH solutions. The mixture was then incubated in a thermostatic oscillator at 37°C and 100 rpm / min for 2 hours to simulate intestinal digestion. The above mixture was taken out every 30 minutes, and an equal amount of SGF / SIF was added to the digestion fluid to keep the volume constant.

[0072] The standard curve was established by measuring the absorbance of different concentrations of curcumin in methanol. The R-squared of the derived calibration equation was 0.9997, as shown in the equation: y = 0.2153x - 0.0315

[0073] where y is the curcumin concentration (μg / mL) and x is the absorbance at 425 nm.

[0074] Next, 200 μL of sample solution and 9.8 mL of methanol were added to the centrifuge tube and centrifuged at 14000 rpm / min for 10 min to remove starch granules. Subsequently, 100 μL of supernatant was added to a cuvette and mixed with 900 μL of methanol. The absorbance at 425 nm was measured. A blank control was prepared by replacing the sample emulsion with an equal volume of water. Finally, the concentration of curcumin in the Pickering emulsion was calculated based on the absorbance measurement results.

[0075] The results of simulated gastrointestinal digestion of curcumin-loaded banana-taro esterified starch and esterified starch nanocrystal-stabilized Pickering emulsions are shown in Figure 4 .

[0076] Results Analysis

[0077] like Figure 1 As shown in part A, most of the banana starch is oval and has a smooth surface. After modification with OSA (OS-starch), the surface of the starch granules becomes slightly rough and pores can be observed ( Figure 1 (Part B). Figure 1 The results of part C show that dry SNCs exhibit aggregation behavior. The aggregates of SNCs appear as irregular polygonal particles with rough surfaces. The aggregates of OS-SNCs exhibit layered grooves ( Figure 1 (section D).

[0078] Figure 2 Part A shows that the new peak at 0.86 ppm in the spectra of OS-starch and OS-SNCs corresponds to the three protons of the terminal methyl groups of the acyl chain, an observation that can be attributed to the introduction of acyl groups during the esterification process. Figure 2 Part B shows that OS-starch has peaks at 1728 and 1573 cm -1 Two new absorption bands are shown at the ester group, which are derived from the C=O stretching vibration of the ester group and the carboxylate RCOO - Asymmetric tensile vibration. Figure 2Part C shows that banana starch has a B-type crystal structure, with obvious diffraction peaks at 5.68°, 14.88°, 17.04°, 19.76°, 22.18° and 23.98° (2θ). The characteristic diffraction peaks of SNCs are sharper. In addition, after esterification, the relative crystallinity of starch and SNCs decreased to 30.17% and 43.63%, respectively. Figure 2 In part D, it can be observed that esterification modification enhances the hydrophobicity of starch and SNCs, showing emulsification potential and forming stable Pickering emulsions.

[0079] Figure 3 Parts A and B show the Pickering emulsions stabilized by OS-starch and OS-SNCs at different MCT ratios (20% to 80%). In the case of OS starch Pickering emulsion, an increase in Φ from 20% to 60% resulted in a corresponding increase in the emulsion layer. However, at Φ values ​​of 70% and 80%, oil-water separation occurred and the emulsion layer disappeared. Figure 3 Parts A1 and B1 show that when Φ increases to 60%, the number of emulsion droplets increases, the gap between the droplets becomes smaller, and the size of the droplets becomes more uniform. At this point, the emulsion is relatively stable.

[0080] like Figure 4 As shown in the figure, after 2 h of digestion in gastric juice, the release rates of curcumin in Pickering emulsions stabilized by OS-starch and OS-SNCs were 17.16% and 14.24%, respectively. In the subsequent digestion in simulated intestinal juice, the release rates of curcumin reached 70.51% and 63.01%, respectively, indicating that they have a protective effect on curcumin in simulated gastric juice. This indicates that Pickering emulsions stabilized by OS-starch and OS-SNCs have good controlled release ability.

[0081] Therefore, the banana-taro esterified starch and the Pickering emulsion stabilized by the esterified starch nanocrystal prepared by the preparation method provided by the present invention both have uniform droplet size and good stability, among which the Pickering emulsion stabilized by the esterified starch nanocrystal has better effect; it has pseudoplastic fluid behavior; it shows good carrier performance and sustained-release effect on bioactive compounds, and also shows good intestinal flora regulation ability, and can be applied to the transportation of bioactive substances and new prebiotic foods; the preparation method is simple and easy to operate, does not require high temperature and high pressure, has low requirements on instruments and equipment, the raw materials and products are safe and non-toxic, and the preparation process does not emit toxic and harmful substances, is green and environmentally friendly, and has no safety hazards.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals, characterized in that: Here are the steps: S1. Preparation of SNCs: adding a certain amount of sulfuric acid solution to a certain amount of banana and taro starch, stirring and mixing to obtain a starch dispersion, stirring the starch dispersion for 5-6 days and then centrifuging to obtain a precipitate, washing the precipitate with distilled water for 2-3 times, and freeze-drying the precipitate to obtain SNCs powder; S2, preparing OS-starch and OS-SNCs, respectively weighing a certain amount of banana taro starch and the SNCs powder prepared in step S1, dispersing them in distilled water, adjusting the pH to 8.0-9.5, slowly dripping OSA, stirring while dripping, and maintaining the pH at 8.0-9.

5. After reacting for 2 hours, adjusting the pH of the reaction mixture to 6.0-7.0, centrifuging to remove the supernatant, washing the precipitate with distilled water 2-3 times, and drying the precipitate to obtain OS-starch and OS-SNCs; S3. Preparing Pickering emulsions stabilized by OS-starch and OS-SNCs. Weigh a certain amount of OS-starch prepared in step S2 and OS-SNCs prepared in step S3, respectively, and disperse them in distilled water to obtain OS-starch dispersion and OS-SNCs dispersion. Add MCT to the above dispersions, respectively, and homogenize for 3 minutes to obtain OS-starch stabilized Pickering emulsions and OS-SNCs stabilized Pickering emulsions.

2. The method for preparing the Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals according to claim 1, characterized in that: The concentration of the sulfuric acid solution in step S1 is 3.16 mol / L, and the banana and taro starch accounts for 10%-40% of the total mass of the starch dispersion; the stirring speed of the starch dispersion is 400 rpm / min, and the stirring temperature is 35°C; the centrifugal condition is: centrifugation at a speed of 4000 rpm / min for 10 minutes.

3. The method for preparing the Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals according to claim 1, characterized in that: In the step S2, the banana and taro starch and the SNCs powder each account for 20%-50% of the total mass of the starch dispersion; and OSA accounts for 3% of the mass of the banana and taro dry starch and the SNCs powder.

4. The method for preparing the Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals according to claim 1, characterized in that: The temperature of the distilled water in step S2 is 30-40°C, and the slow dripping of OSA means that the OSA used is dripped within 1 hour; the drying temperature of the precipitate is 40°C.

5. The method for preparing the Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals according to claim 1, characterized in that: In step S4, OS-starch and OS-SNCs account for 2%-5% of the total mass of the dispersion, the amount of MCT added is 20%-80% of the total mass of the dispersion, and the homogenization speed is 13000 rpm / min.

6. The method for preparing the Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals according to claim 1, characterized in that: The pH adjustment was achieved by NaOH and HCl solutions.

7. A Pickering emulsion stabilized by esterified banana and taro starch and esterified starch nanocrystals prepared by the preparation method according to any one of claims 1 to 6.

8. Use of banana-taro esterified starch and Pickering emulsion stabilized by esterified starch nanocrystals prepared by the preparation method according to any one of claims 1 to 6 in encapsulating food and medicine.

9. An application of banana-taro esterified starch and Pickering emulsion stabilized by esterified starch nanocrystals prepared by the preparation method according to any one of claims 1 to 6 as functional excipients in the fields of traditional Chinese medicine extracts, probiotics embedding, and cosmetics.

Images