Pepper seed oil microcapsule and preparation method thereof

Abstract

The invention relates to a preparation method of Chinese prickly ash seed oil microcapsules, which comprises the following steps: (1) weighing Arabic gum, dissolving the Arabic gum in water, and stirring to obtain a mixture a; (2) adding quinoa polypeptide into the mixture a prepared in the step (1), heating and stirring until the quinoa polypeptide is dissolved to prepare a mixture b; (3) adding an emulsifier into the mixture b prepared in the step (2), and stirring to prepare a mixture c; (4) adding Chinese prickly ash seed oil into the mixture c prepared in the step (3), and emulsifying to prepare an emulsion; and (5) performing spray drying on the emulsion prepared in the step (4) to prepare the Chinese prickly ash seed oil microcapsule. The Chinese prickly ash seed oil is microencapsulated, so that effective components of the Chinese prickly ash seed oil can be protected.

Description

Technical Field

[0001] The present invention belongs to the technical field of microcapsule preparation, and particularly relates to a prickly ash seed oil microcapsule and a preparation method thereof. Background Art

[0002] Prickly ash ( Zanthoxylum bungeanum Maxim ) is a deciduous small tree of the Rutaceae family and the Zanthoxylum genus. Prickly ash seed oil is an edible oil extracted from the processing waste of prickly ash seeds. It contains more than 90% unsaturated fatty acids, including stearic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, etc., and the content of α-linolenic acid is 33.4%. Research shows that the unsaturated fatty acids in prickly ash seed oil can reduce the synthesis of body fatty acids and the accumulation of liver fat droplets and prevent atherosclerosis. Among them, α-linolenic acid also has the functions of regulating blood lipids, anti-inflammatory, and anti-cancer. Prickly ash seed oil is a functional oil with great application potential. However, external factors such as light and air will accelerate the lipid oxidation of prickly ash seed oil, resulting in the loss of nutritional components. In order to apply prickly ash seed oil more widely and stably to foods, it is necessary to select appropriate preparation technologies to better protect its active ingredients.

[0003] Therefore, there is an urgent need to find a solution to protect the unsaturated fatty acids in prickly ash seed oil from oxidative rancidity to the greatest extent during storage. Summary of the Invention

[0004] The purpose of the present invention is to solve the disadvantages existing in the prior art, and to provide a prickly ash seed oil microcapsule and a preparation method thereof to ensure that the unsaturated fatty acids in prickly ash seed oil are not oxidized and rancid during storage.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: A preparation method of a prickly ash seed oil microcapsule, comprising the following steps: (1) Weigh gum arabic and dissolve it in water, and then stir to obtain mixture a; (2) Add quinoa polypeptide to the mixture a obtained in step (1), heat and stir until dissolved to obtain mixture b; (3) Add an emulsifier to the mixture b obtained in step (2) and stir to obtain mixture c; (4) Add prickly ash seed oil to the mixture c obtained in step (3) and emulsify to obtain an emulsion; (5) The emulsion obtained in step (4) is spray-dried to obtain a prickly ash seed oil microcapsule.

[0006] Preferably, the mass ratio of the gum arabic to the quinoa polypeptide is 3:1 - 1:3 (g / g).

[0007] Preferably, the addition amount of the emulsifier in step (3) is 1%-3%, and the emulsifier consists of Tween-80.

[0008] Preferably, the prickly ash seed oil is used as the core material, and arabic gum and quinoa polypeptide are used as the wall materials, and the mass ratio of the core material to the wall materials is 0.2-0.6:1 (g / g).

[0009] Preferably, the solid content is all substances except water, including arabic gum, quinoa polypeptide, emulsifier, and prickly ash seed oil, and the addition amount of the solid content is 17%-29%.

[0010] Preferably, in step (4), after adding prickly ash seed oil to the mixture c prepared in step (3), high-speed shear emulsification is carried out at 9000-15000 r / min for 3-5 min to obtain an emulsion.

[0011] Preferably, the feeding amount of the emulsion in step (5) is 2-6.6 mL / min.

[0012] Preferably, the inlet air temperature of spray drying in step (5) is 140-180 °C.

[0013] Preferably, the outlet air temperature of spray drying in step (5) is 85 °C.

[0014] In addition, the present invention also provides a prickly ash seed oil microcapsule prepared according to the above method.

[0015] The present invention has the following beneficial effects: The present invention successfully prepares prickly ash seed oil microcapsules by spray drying method. Through single factor and response surface experiments, the optimal preparation process conditions of prickly ash seed oil microcapsules are as follows: the addition amount of emulsifier is 2.16%, the mass ratio of arabic gum to quinoa polypeptide is 1:1.46 (g / g), the core-wall ratio is 0.34:1 (g / g), the addition amount of solid content is 23% (g / g), the inlet air temperature is 170 °C, and the feeding amount is 4.7 mL / min. Under these conditions, the embedding rate reaches 90.7%. The results of scanning electron microscopy, particle size analysis, moisture content, bulk density, particle size, and thermogravimetric analysis show that the prickly ash seed oil microcapsules are in a relatively smooth spherical shape, with complete structure, uniform particle size, and good fluidity, thermal stability, and dispersibility. The in vitro simulated gastrointestinal fluid release results show that after simulated gastrointestinal digestion, the core material of the microcapsules is almost completely released. Encapsulating prickly ash seed oil is beneficial to protecting the active ingredients of prickly ash seed oil, improving its digestion and absorption effect, expanding its application range, and being suitable for the application in the food industry. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings: Figure 1 It is a diagram showing the influence of a single factor on the encapsulation rate of prickly ash seed oil microcapsules; Figure 2 It is a diagram showing the influence of spray drying conditions on the encapsulation rate of prickly ash seed oil microcapsules; Figure 3 It is a response surface diagram and contour map showing the interaction relationship between the solid content and the addition amount of emulsifier; Figure 4 It is a response surface diagram and contour map showing the interaction relationship between the solid content and the proportion of wall material; Figure 5 It is a response surface diagram and contour map showing the interaction relationship between the solid content and the core-wall ratio; Figure 6 It is a response surface diagram and contour map showing the interaction relationship between the addition amount of emulsifier and the proportion of wall material; Figure 7 It is a response surface diagram and contour map showing the interaction relationship between the addition amount of emulsifier and the core-wall ratio; Figure 8 It is a response surface diagram and contour map showing the interaction relationship between the proportion of wall material and the core-wall ratio; Figure 9 It is a particle size distribution diagram of prickly ash seed oil microcapsules; Figure 10 It is a SEM diagram of prickly ash seed oil microcapsules; Figure 11 It is a thermogravimetric curve diagram of prickly ash seed oil microcapsules; Figure 12 It is a core material release rate diagram of prickly ash seed oil microcapsules during in vitro simulated digestion process. Specific Embodiments

[0017] For better understanding of the present invention, it is illustrated by the following examples. These examples belong to the protection scope of the present invention, but do not limit the protection scope of the present invention.

[0018] Example 1 A preparation method of prickly ash seed oil microcapsules includes the following steps: (1) Weigh arabic gum and dissolve it in distilled water at 50 °C, then stir for 30 min to obtain mixture a; (2) Add quinoa polypeptide to the mixture a prepared in step (1) and heat with stirring until dissolved to obtain mixture b; (3) Add an emulsifier to the mixture b obtained in step (2) and stir to obtain a mixture c; (4) Add prickly ash seed oil to the mixture c obtained in step (3) and perform high-speed shear emulsification at 15,000 r / min for 5 min to obtain an emulsion; (5) The emulsion obtained in step (4) is spray-dried to obtain prickly ash seed oil microcapsules.

[0019] The mass ratio of the arabic gum to the quinoa polypeptide is 2:1 (g / g).

[0020] In step (3), the addition amount of the emulsifier is 2.5%, and the emulsifier is Tween-80.

[0021] In step (4), the prickly ash seed oil is the core material, and the arabic gum and the quinoa polypeptide are the wall materials. The mass ratio of the core material to the wall materials is 0.4:1 (g / g).

[0022] The solid content is all substances except water, including arabic gum, quinoa polypeptide, emulsifier, and prickly ash seed oil. The addition amount of the solid content is 23% (g / g).

[0023] In step (5), the feeding rate of the emulsion is 3.3 mL / min.

[0024] In step (5), the inlet air temperature of the spray drying is 160 °C.

[0025] In step (5), the outlet air temperature of the spray drying is 85 °C.

[0026] Example 2 A method for preparing prickly ash seed oil microcapsules, comprising the following steps: (1) Weigh arabic gum and dissolve it in distilled water at 50 °C, and then stir for 30 min to obtain a mixture a; (2) Add quinoa polypeptide to the mixture a obtained in step (1), heat and stir until dissolved to obtain a mixture b; (3) Add an emulsifier to the mixture b obtained in step (2) and stir to obtain a mixture c; (4) Add prickly ash seed oil to the mixture c obtained in step (3) and perform high-speed shear emulsification at 9,000 r / min for 3 min to obtain an emulsion; (5) The emulsion obtained in step (4) is spray-dried to obtain prickly ash seed oil microcapsules.

[0027] The mass ratio of the arabic gum to the quinoa polypeptide is 1:1 (g / g).

[0028] In step (3), the addition amount of the emulsifier is 2%, and the emulsifier is Tween-80.

[0029] In step (4), the prickly ash seed oil is used as the core material, and arabic gum and quinoa polypeptide are used as the wall materials, and the mass ratio of the core material to the wall materials is 0.3:1 (g / g).

[0030] The solid content is all substances except water, including arabic gum, quinoa polypeptide, emulsifier, and prickly ash seed oil, and the addition amount of the solid content is 20%.

[0031] In step (5), the feeding rate of the emulsion is 4 mL / min.

[0032] In step (5), the inlet air temperature of the spray drying is 170 °C.

[0033] In step (5), the outlet air temperature of the spray drying is 85 °C.

[0034] Example 3 A preparation method of prickly ash seed oil microcapsules includes the following steps: (1) Weigh arabic gum and dissolve it in distilled water at 50 °C, and then stir for 30 min to obtain mixture a; (2) Add quinoa polypeptide to the mixture a obtained in step (1), heat and stir until dissolved to obtain mixture b; (3) Add an emulsifier to the mixture b obtained in step (2) and stir to obtain mixture c; (4) Add prickly ash seed oil to the mixture c obtained in step (3), and perform high-speed shear emulsification at 12000 r / min for 4 min to obtain an emulsion; (5) The emulsion obtained in step (4) is subjected to spray drying to obtain prickly ash seed oil microcapsules.

[0035] The mass ratio of the arabic gum to the quinoa polypeptide is 1:2 (g / g).

[0036] In step (3), the addition amount of the emulsifier is 1.5%, and the emulsifier is composed of sucrose ester and monoglyceride according to the mass ratio of 1:1.

[0037] In step (4), the prickly ash seed oil is used as the core material, and arabic gum and quinoa polypeptide are used as the wall materials, and the mass ratio of the core material to the wall materials is 0.2:1 (g / g).

[0038] The solid content is all substances except water, including arabic gum, quinoa polypeptide, emulsifier, and prickly ash seed oil, and the addition amount of the solid content is 17%.

[0039] In step (5), the feeding rate of the emulsion is 4.7 mL / min.

[0040] In step (5), the inlet air temperature of the spray drying is 180 °C.

[0041] In step (5), the outlet air temperature of the spray drying is 85 °C.

[0042] Example 4 To explore the influence of single factors on the optimization of the preparation process of prickly ash seed oil microcapsules and simultaneously conduct the property analysis of prickly ash seed oil microcapsule products, the Box-Behnken design response surface was used to optimize the process conditions for preparing prickly ash seed oil microcapsules by spray drying, and the following experiments were carried out on property analysis, particle size analysis, in vitro simulated release test analysis, etc.

[0043] 1 Materials and Methods 1.1 Materials and Reagents Prickly ash seed oil was purchased from Yanshan, Hebei. Arabic gum was from Shanghai Macklin Biochemical Co., Ltd.; quinoa polypeptide was from Xi'an Phytochemical Biotechnology Co., Ltd.; Tween-80 was from Shanghai Macklin Biochemical Co., Ltd.; the above reagents were all food additives. Petroleum ether (60℃-90℃, analytical pure) was from Beijing Zhengcheng Biotechnology Co., Ltd.; pepsin and trypsin were from Shanghai Yuanye Biotechnology Co., Ltd.

[0044] 1.2 Instruments and Equipment Sigma 360 scanning electron microscope (Carl Zeiss AG, Germany); Bettersize 3000 laser particle size analyzer (Dandong Baite Instrument Co., Ltd.); TG / DTA 8122 thermogravimetric analyzer (Rigaku Corporation, Japan); Nicolet iS20 Fourier transform infrared spectrometer (Thermo Fisher Scientific, USA); HF-015 experimental spray dryer (Shanghai HeFan Instrument Co., Ltd.); FSH-2A adjustable high-speed homogenizer (Changzhou Jinnan Instrument Manufacturing Co., Ltd.); C-08-2 heating magnetic stirrer (Shanghai Medical Equipment Special Machine Factory); Secura 513-1CN electronic balance (Sartorius AG, USA); SHZ-D(Ⅲ) desktop circulating water vacuum pump (Gongyi Yuhua Instrument Co., Ltd.); PHS-3C pH meter (Leici Shanghai Yidian Scientific Instrument Co., Ltd.).

[0045] 1.3 Methods 1.3.1 Preparation of Prickly Ash Seed Oil Microcapsules Weigh a certain amount of Arabic gum and dissolve it in distilled water at 50℃, stir it at a constant temperature for 30 min, then add a certain amount of quinoa polypeptide and heat and stir until dissolved, then add a certain amount of emulsifier Tween-80, slowly add a certain amount of prickly ash seed oil, and emulsify the emulsion at 15000 r / min for 5 min to obtain a uniform emulsion. The emulsion is spray-dried to obtain prickly ash seed oil microcapsule powder, and the outlet temperature of spray drying is 85℃.

[0046] 1.3.2 Optimization of the Preparation Process of Prickly Ash Seed Oil Microcapsules 1.3.2.1 Single-Factor Experiment Under the conditions of the mass ratio of gum arabic to quinoa polypeptide being 1:1, the core-wall ratio being 0.3, the emulsifier addition being 2%, the inlet air temperature being 170 °C, and the feed flow rate being 4.7 mL / min, the effects of solid content being 17%, 20%, 23%, 26%, and 29% on the encapsulation rate of prickly ash seed oil microcapsules were investigated.

[0047] Under the conditions of the wall material ratio being 1:1, the core-wall ratio being 0.3, the solid content being 20%, the inlet air temperature being 170 °C, and the feed flow rate being 4.7 mL / min, the effects of the emulsifier addition amounts being 1%, 1.5%, 2%, 2.5%, and 3% on the encapsulation rate of prickly ash seed oil microcapsules were investigated.

[0048] Under the conditions of the core-wall ratio being 0.3:1, the emulsifier addition amount being 2%, the solid content being 20%, the inlet air temperature being 170 °C, and the feed flow rate being 4.7 mL / min, the effects of the wall material ratios being 1:3, 1:2, 1:1, 2:1, and 3:1 on the encapsulation rate of prickly ash seed oil microcapsules were investigated.

[0049] Under the conditions of the wall material ratio being 1:1, the solid content being 20%, the emulsifier addition amount being 2%, the inlet air temperature being 170 °C, and the feed flow rate being 4.7 mL / min, the effects of the core-wall ratios being 0.2, 0.3, 0.4, 0.5, and 0.6 on the encapsulation rate of prickly ash seed oil microcapsules were investigated.

[0050] Under the conditions of the wall material ratio being 1:1, the core-wall ratio being 0.3, the emulsifier addition being 2%, the solid content being 20%, and the feed flow rate being 4.7 mL / min, the effects of the inlet air temperatures being 140 °C, 150 °C, 160 °C, 170 °C, and 180 °C on the encapsulation rate of prickly ash seed oil microcapsules were investigated.

[0051] Under the conditions of the wall material ratio being 1:1, the core-wall ratio being 0.3, the emulsifier addition being 2%, the solid content being 20%, and the inlet air temperature being 170 °C, the effects of the feed flow rates being 2, 3.3, 4.7, 6, and 7.3 mL / min on the encapsulation rate of prickly ash seed oil microcapsules were investigated.

[0052] 1.3.2.2 Response surface experiment On the basis of the single-factor experiment, with the encapsulation rate of prickly ash seed oil as the response value, the solid content, core-wall ratio, wall material ratio, and emulsifier addition amount were selected as the investigation factors, and a four-factor and three-level response surface experiment was carried out. The specific experimental factors and levels are shown in Table 1.

[0053] Table 1 Response surface experiment factors and levels 1.3.3 Property analysis of prickly ash seed oil microcapsule products 1.3.3.1 Determination of the encapsulation rate of prickly ash seed oil microcapsules Surface oil content of microcapsule product: Weigh an appropriate amount of prickly ash seed oil microcapsules precisely into a beaker, add 10 times the amount of petroleum ether, shake for 30 s, then filter by suction. Wash the filter residue twice with 5 times the amount of petroleum ether, collect the filtrate in a pre-weighed conical flask, evaporate the solvent, and then dry the conical flask in an oven at 105 °C until constant weight, and record the total weight.

[0054] Total oil content of microcapsule product: Mix 1 g of the sample with 15 ml of hydrochloric acid solution (4 mol / L) in a centrifuge tube by vortexing, and then place it in a water bath at 80 °C for 1 h. After hydrolysis, take it out and cool to room temperature. Open the lid, add 20 mL of petroleum ether and 10 mL of 95% ethanol, tighten the lid, shake vigorously for 40 s, centrifuge at 5000 r / min for 10 min at room temperature, aspirate the upper layer of petroleum ether containing the total oil into a pre-weighed flask, dry it to constant weight at 60 °C, and determine the total oil content by gravimetric analysis.

[0055] The calculation formula of the encapsulation efficiency is as follows: Where: m is the surface oil content of the microcapsule / g; M is the total oil content of the microcapsule / g; Y is the encapsulation efficiency of the microcapsule / %.

[0056] 1.3.3.2 Determination of water content of microcapsules The determination of the water content of microcapsules refers to GB / T5009.3-2016 "Determination of water content in foods". Place the microcapsule product in an oven at 105 °C and dry it to constant weight.

[0057] 1.3.3.3 Determination of bulk density of microcapsules Pour the microcapsule product into a 10 mL graduated cylinder, shake and tamp it to make the microcapsules fill to the graduation line of the graduated cylinder, record the mass (M) of the filled microcapsules and the filled volume (V) of the graduated cylinder, and calculate the bulk density of the microcapsules.

[0058] Where: d is the bulk density of the microcapsules, g / cm 3 ; M is the mass of the filled microcapsules, g; V is the filled volume of the microcapsules, cm 3 .

[0059] 1.3.3.4 SEM determination Uniformly coat the prickly ash seed oil microcapsule powder on the conductive tape, perform gold spraying on the microcapsules with an ion sputtering instrument, observe the microscopic morphology and surface structure with a desktop scanning electron microscope, the acceleration voltage is 20.0 KV, the magnification is 100 - 5000 times, select a suitable field of view, and save the microcapsule view. 1.3.3.5 Thermogravimetric (TG) determination Take appropriate amounts of prickly ash seed oil, prickly ash seed oil microcapsule powder, gum arabic, and quinoa polypeptide and place them in the sample pan of a synchronous thermogravimetric analyzer. Set the temperature range of the instrument's heating program to 30 - 800 °C, use nitrogen as the protective gas, and set the heating rate to 20 °C / min. Then plot the corresponding thermogravimetric loss trend graph.

[0060] 1.3.3.6 In vitro simulated release Dissolve 2 g of sodium chloride in 900 mL of distilled water, adjust the pH value of the sodium chloride solution to 1.5 with hydrochloric acid solution, add 3.2 g of pepsin, and then add distilled water to 1000 mL to prepare simulated gastric juice. Dissolve 9.6 g of dipotassium hydrogen phosphate, 4.44 g of calcium chloride, 8.76 g of sodium chloride, and 5 g of bile salts in 900 mL of distilled water. After adjusting the pH value to 7.0 with sodium hydroxide solution, add 50 g of pancreatin and make up the volume to 1000 mL with distilled water to prepare simulated intestinal fluid.

[0061] In vitro simulated digestion: Take 10 mL of 20% microcapsule aqueous solution and mix it with simulated gastric juice at a volume ratio of 1:1. After adjusting the pH value to 2.5 with 1 mol / L sodium hydroxide solution, incubate it in a shaker at 200 r / min at (37 ± 1) °C for 2 h, and titrate it with 0.2 mol / L sodium hydroxide solution to keep it at pH 2.5. Add an equal volume of simulated intestinal fluid to the 20 mL digestion product of simulated gastric juice. Adjust the pH value to 7.0 with 1 mol / L sodium hydroxide solution. During the digestion process, detect the change of pH value with a pH meter, and titrate it with 0.2 mol / L sodium hydroxide solution to keep it at pH 7.0, and record the volume of 0.2 mol / L sodium hydroxide solution consumed. Calculate the free fatty acid release rate of the sample according to formula (5).

[0062] In the formula, M is the molar mass of prickly ash seed oil, and m is the mass of prickly ash seed oil 2 Results and analysis 2.1 Results of single-factor experiments 2.1.1 Effect of core-wall ratio on the encapsulation rate of prickly ash seed oil microcapsules As can be seen from Figure 1A, with the increase of the core-wall ratio, the encapsulation rate first increases and then decreases, and the encapsulation rate is the highest when the core-wall ratio is 0.3. When the core-wall ratio is relatively low, the excessive content of wall material makes the viscosity of the emulsion too high, and it is difficult for the microcapsule particles to achieve a good atomization effect during spray drying, resulting in the core material being adsorbed on the surface of the microcapsules and the encapsulation rate decreasing. When the proportion of the wall material is relatively low, due to the relatively thin outer wall of the microcapsules formed by spray drying, it is easier for the prickly ash seed oil to ooze out, resulting in a relatively high oil content on the surface of the microcapsule powder.

[0063] 2.1.2 Effect of solid content on the encapsulation rate of prickly ash seed oil microcapsules As can be seen from Figure 1 B, within the range of solid content concentrations explored in this experiment, the encapsulation efficiency first increases and then decreases with the increase in solid content. The solid content concentration affects the particle size of the spray-dried microcapsules. The encapsulation effect is the best when the solid content concentration is 20%. Continuing to increase the solid content concentration will lead to an increase in the viscosity of the emulsion, resulting in larger particles formed by spraying and higher moisture content, reducing the encapsulation efficiency.

[0064] 2.1.3 Effect of Emulsifier Dosage on the Encapsulation Efficiency of Camellia bungeana Seed Oil Microcapsules As can be seen from Figure 1 C, the microcapsule encapsulation efficiency is the highest when the emulsifier dosage is 2%. The proportion of the emulsifier in the emulsion affects the stability. When the proportion of the emulsifier is relatively low, the solution cannot form critical micelles, and the stability of the emulsion will be relatively poor, and stratification will occur after long-term placement; if the proportion of the emulsifier is relatively high, it will lead to too high a critical micelle concentration, resulting in too high a viscosity of the emulsion and making it difficult to carry out normal spray drying.

[0065] 2.1.4 Effect of Wall Material Ratio on the Encapsulation Efficiency of Camellia bungeana Seed Oil Microcapsules As can be seen from Figure 1 D, the wall material has an important influence on the preparation of oil microcapsules. Gum arabic is a natural amphiphilic macromolecule. As the proportion of gum arabic in the wall material increases, the encapsulation efficiency of Camellia bungeana seed oil microcapsules first shows an upward trend and then a downward trend. When the compounding ratio of quinoa polypeptide and gum arabic is 1:1, the microcapsule encapsulation efficiency is the highest. This may be because the viscosity of the emulsion gradually increases with the increase in the proportion of gum arabic, which is not conducive to the spraying of the spray drying nozzle, resulting in some microcapsules being oxidized due to long-term heating, reducing the encapsulation efficiency; when the proportion of gum arabic decreases, it will lead to a decline in the emulsification effect of the emulsion, resulting in fewer microcapsules prepared and reducing the encapsulation efficiency.

[0066] 2.2 Screening of Spray Drying Conditions Determining the appropriate feeding speed and inlet air temperature is also a key factor in the preparation of high-quality microcapsules. As can be seen from Figure 2 A, within the range of feeding speeds of 6 - 22 r / min, the encapsulation effect of microcapsules first increases and then decreases with the increase in speed. The feeding speed has a direct impact on the moisture evaporation rate of microcapsules during spray drying. When the feeding speed is relatively low, it is conducive to the atomization and drying of the emulsion, but at this time, the moisture of the microcapsules evaporates too quickly, resulting in cracks on the outer wall and easy leakage of Camellia bungeana seed oil. When the feeding speed is 14 r / min, the effect of encapsulating Camellia bungeana seed oil by spray drying is the best, and the encapsulation efficiency reaches 90.6%. Continuing to increase the feeding speed will cause a decrease in atomization efficiency, poor drying effect of microcapsules, high moisture content, and wall sticking phenomenon, affecting the quality of microcapsules. Figure 2B shows that when the air inlet temperature is low, the evaporation rate of the microcapsule water is slow, and the surface of the emulsion droplets cannot form a hard microcapsule outer wall in time, resulting in the wall material not being able to completely embed the core material. At the same time, higher residual moisture can easily cause the emulsion to adhere to the tube wall during the spray drying process, reducing the embedding rate and yield rate. With the increase of the air inlet temperature, the evaporation of water is accelerated, the formation rate of the microcapsule surface shell increases, and the embedding rate increases accordingly. At 170°C, the embedding rate of pepper seed oil reaches 90.32%. The air inlet temperature and feed rate of spray drying are important factors affecting the quality of pepper seed oil microcapsules. Under optimal conditions, these two factors can control the overall moisture content of the microcapsules within an appropriate range and improve the stability of the microcapsules during storage.

[0067] 2.3 Response surface optimization test results 2.3.1 Model establishment and significance test results The response surface experiment was designed using Design-expert software. Four factors and three levels were combined into 29 groups of experiments. The experiments were carried out according to the conditions, with 3 parallels in each group. The results are shown in Table 2. The regression model was fitted based on the results, and the quadratic polynomial regression equation for the embedding rate of Zanthoxylum bungeanum seed oil microcapsules was: Y=90.31+0.3958A+1.6B+0.5008C+1.1D+1.97AB+0.3AC+0.615AD-0.78BC-1.93BD+0.4675CD-1.29A 2 -3.54B 2 -1.84C 2 -1.82D 2 The variance analysis of the model is shown in Table 3. Table 3 shows that the model is extremely significant (P<0.01), the significance of the lack of fit item is not significant, and the determination coefficient R 2 =0.9766, greater than 0.95, R 2 adj=0.9531, indicating that the model is feasible and reliable. The size of F represents the strength of the effect on the embedding rate. Therefore, the amount of emulsifier added has the greatest effect on the embedding rate of microcapsules, followed by the core-wall ratio. In addition, the interaction terms AB, AD, BC, BD, CD and the quadratic terms A², B², C², and D² have a significant effect on the embedding rate (P<0.05). The optimal process parameters and expected results obtained using the microcapsule embedding rate regression equation are: solid concentration 20.69%, emulsifier addition 2.03%, wall material ratio 1:1.71, and core-wall ratio 0.34:1. The embedding rate obtained under the optimal process parameters as the production conditions is 90.7%, and the actual value is close to the predicted value, indicating that the process is feasible.

[0068] Table 2 Response surface design and results Analysis of Variance of the Regression Model in Table 3 2.3.2 Response Surface Analysis of Interaction Please refer to the 3D surface plots and contour plots for the interactive effects of solid content, emulsifier addition amount, wall material ratio, and core-wall ratio on microcapsule embedding Figures 3 - 8 , Figures 3 - 8 The openings of the 3D surface plots in [] are all downward, indicating a maximum value. The elliptical contour plots represent obvious interactions, and the density of the contour lines represents the strength relationship in the interactions. The denser the lines, the stronger the influence. It can be seen that the interaction between the emulsifier addition amount and the core-wall ratio is obvious, and the lines closer to the emulsifier addition amount are denser, indicating a stronger influence. In summary, the order of the influence of solid content, core-wall ratio, emulsifier dosage, and wall material ratio on the microencapsulation rate of microcapsules is: emulsifier addition amount > core-wall ratio > wall material ratio > solid content, which is consistent with the F result in the analysis of variance

[0069] 2.3.3 Verification Test Using Design-Expert V8.06 software to analyze the process conditions, the optimal process conditions for preparing prickly ash seed oil microcapsules are obtained as follows: wall material ratio 1:1.46, emulsifier addition amount 2.16%, solid content 23%, core-wall ratio 0.34:1, inlet air temperature 170 °C, and feed rate 4.7 mL / min. The predicted value of the encapsulation rate of prickly ash seed oil microcapsules is 90.61%

[0070] 2.4 Property Analysis The moisture content of microcapsule powder is related to its storage stability. Powders with a water activity < 0.30 are considered not conducive to the survival of microorganisms and can resist spoilage caused by them. However, a moisture content exceeding 5% will cause the microcapsule powder to agglomerate, resulting in a decrease in sealing and making the oil more prone to oxidative rancidity, seriously affecting the quality of microcapsules. After measurement, the moisture content of prickly ash seed oil microcapsules is 2.97%, which meets the moisture standard (≤5%) of docosahexaenoic acid oil powder specified in QB / T 5632-2012, has excellent quality of microcapsules, and is conducive to the storage of prickly ash seed oil microcapsules. The bulk density of microcapsules affects storage. A larger density is beneficial for reducing storage space and thus reducing costs. The bulk density of the powder is 0.32 g / mL, which is at a good level. The above results indicate that it has good food processing characteristics

[0071] 2.5 Particle Size and Solubility Analysis Please refer to Figure 9, the quality of microcapsules is closely related to their particle size range. Particles with a particle size between 20 - 40 μm have a relatively high dissolution ability and good dissolution and dispersion in water. A larger particle size distribution range indicates that the morphology of the microcapsules is more uneven, which will lead to a decrease in solubility and oxidation stability. The particle size distribution range of the prickly ash seed oil microcapsule powder obtained by the optimal process is relatively concentrated between 1 μm - 10 μm, with an average particle size of 5.659 μm and a solubility of 93.17% in distilled water at room temperature. This shows that the prickly ash seed oil microcapsules prepared by spray drying have the oxidation stability and good solubility of small particle size powder oils.

[0072] 2.6 SEM The microscopic structure of microcapsules can explain some of their physical and chemical properties, such as fluidity and the encapsulation effect on the internal core material, etc., which is of great significance for the encapsulation and protection of prickly ash seed oil. Please refer to Figure 10 , overall, the prickly ash seed oil microcapsules are all approximately spherical particles. This is because the solvent that dissolves the wall material in the emulsion droplets will quickly evaporate through the high-temperature drying hot air flow in the drying chamber, causing the wall material to form a network structure to embed the core material. The intake air volume of the spray drying device used in the laboratory cannot be completely constant, which will lead to different evaporation rates of the wall material solvent, resulting in different sizes and shapes of the microcapsules. There are wrinkles and depressions on the surface of the prickly ash seed oil microcapsules, which may be related to the inconsistent evaporation rate of the water in the emulsion droplets, or may be related to the curing rate of the wall material being greater than the expansion rate of the high-temperature drying hot air flow during the cooling stage.

[0073] 2.7 TG Thermogravimetric analysis shows the heat resistance of the sample. As Figure 11As shown, the weight loss of prickly ash seed oil, prickly ash seed oil microcapsules, gum arabic, and quinoa polypeptide can be divided into two stages. The first stage is below 150 °C, mainly due to the evaporation of water and the volatilization of small molecular weight substances. The second stage is above 150 °C, where weight loss is caused by the breaking of chemical bonds. The mass loss of quinoa polypeptide in the second stage is mainly attributed to the degradation of protein peptides. The cleavage of non-covalent bonds such as intermolecular and intramolecular hydrogen bonds, electrostatic, and hydrophobic interactions, as well as the breaking of covalent bonds between amino acid residues, jointly result in the mass loss in this stage, and this part of the weight loss occurs between 150 - 400 °C. The weight loss of gum arabic mainly occurs between 250 - 400 °C, which is caused by the dehydration, decomposition, and depolymerization of carbohydrate rings. The thermal stability of prickly ash seed oil is higher than that of gum arabic and quinoa polypeptide. Its weight loss mainly occurs between 390 - 500 °C, with a loss of 81.72%. After the temperature is greater than 500 °C, the remaining mass is only 0.82%. The prickly ash seed oil microcapsules only lose 3.49% of their weight under the condition of below 150 °C, of which 2.97% is due to water loss. Currently, the ultra-high temperature instantaneous sterilization method is commonly used in the food industry, with a temperature below 150 °C. Therefore, it can be stored at room temperature and meet the thermal processing requirements of most foods.

[0074] 2.8 In vitro simulated release To detect the targeted delivery function of prickly ash seed oil microcapsules as a carrier of unsaturated fatty acids to specific parts of the gastrointestinal tract, the present invention evaluated its release behavior during gastrointestinal transit. As Figure 12 shown, the prickly ash seed oil microcapsules exhibited good sustained-release characteristics in the in vitro digestion experiment. During the simulated gastric juice digestion stage, all of the prickly ash seed oil was released from the core-wall material mixture at 60 min, while the release amount of free fatty acids from the microcapsules was only 22.99% in the 0 - 120 min period. This is because the gum arabic in the microcapsule wall material has low solubility in the acidic environment of simulated gastric juice and slow cleavage speed, preventing the entry of pepsin, and quinoa polypeptide has strong resistance to pepsin hydrolysis, providing good protection for the core material. During the simulated intestinal digestion process, trypsin, lipase, and bile salts in the intestinal fluid disrupted the interaction between proteins and polysaccharides, and a large amount of the core material was released. When digestion reached 300 min, the core material was almost completely released, with a total release rate as high as 82.37%. This characteristic of resisting gastric juice digestion and releasing a large amount in the intestine can ensure that most of the prickly ash seed oil is digested and absorbed in the small intestine, improving the bioavailability.

[0075] 3 Conclusion The microcapsules of Zanthoxylum bungeanum seed oil were successfully prepared by spray drying method. Through single factor and response surface experiments, the optimal preparation process conditions of the microcapsules of Zanthoxylum bungeanum seed oil were obtained as follows: the addition amount of emulsifier was 2.16%, the mass ratio of gum arabic to quinoa polypeptide was 1:1.46 (g / g), the core-wall ratio was 0.34:1 (g / g), the addition amount of solids was 23%, the inlet air temperature was 170 °C, and the feeding rate was 4.7 mL / min. Under these conditions, the encapsulation rate reached 90.7%. The results of scanning electron microscopy, particle size analysis, moisture content, bulk density, particle size and thermogravimetric analysis showed that the microcapsules of Zanthoxylum bungeanum seed oil were spherical with relatively smooth surface, complete structure, uniform particle size and had good fluidity, thermal stability and dispersibility. The results of in vitro simulated gastrointestinal fluid release showed that the microcapsules could resist gastric juice digestion and the core material of the microcapsules was almost completely released in the intestine. Encapsulating Zanthoxylum bungeanum seed oil was beneficial to protect the effective components of Zanthoxylum bungeanum seed oil, improve its digestion and absorption effect, expand its application range and was suitable for the application in the food industry.

[0076] The above content cannot determine that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, which should all be regarded as belonging to the patent protection scope determined by the claims submitted for the present invention.

Claims

1. A method for preparing prickly ash seed oil microcapsules, characterized in that: The steps include: (1) Weighing gum arabic and dissolving it in water, followed by stirring, to prepare a mixture a; (2) adding quinoa polypeptide to the mixture a obtained in step (1), heating and stirring until dissolved, to obtain a mixture b; (3) adding an emulsifier to the mixture b obtained in step (2) and stirring to obtain a mixture c; (4) adding prickly ash seed oil to the mixture c obtained in step (3) and emulsifying the mixture to obtain an emulsion; (5) The emulsion obtained in step (4) is spray-dried to obtain pepper seed oil microcapsules.

2. The method for preparing Zanthoxylum bungeanum seed oil microcapsules according to claim 1, characterized in that: The mass ratio of the gum arabic to the quinoa polypeptide is 3:1-1:3 (g / g).

3. The method for preparing Zanthoxylum bungeanum seed oil microcapsules according to claim 1, characterized in that: The amount of the emulsifier added in step (3) is 1%-3%, and the emulsifier consists of Tween-80.

4. The method for preparing Zanthoxylum bungeanum seed oil microcapsules according to claim 1, characterized in that: The prickly ash seed oil is used as the core material, and the gum arabic and quinoa polypeptide are used as the wall material. The mass ratio of the core material to the wall material is 0.2-0.6:1 (g / g).

5. The method for preparing Zanthoxylum bungeanum seed oil microcapsules according to claim 1, characterized in that: Solids are everything except water, including gum arabic, quinoa polypeptide, emulsifier, and prickly ash seed oil, and the added amount of solids is 17%-29%.

6. The method for preparing Zanthoxylum bungeanum seed oil microcapsules according to claim 1, characterized in that: In step (4), the mixture c obtained in step (3) is added with prickly ash seed oil, and then high-speed shearing emulsification is performed at 9000-15000 r / min for 3-5 minutes to obtain an emulsion.

7. The method for preparing Zanthoxylum bungeanum seed oil microcapsules according to claim 1, characterized in that: The feed rate of the emulsion in step (5) is 2-6.6 mL / min.

8. The method for preparing Zanthoxylum bungeanum seed oil microcapsules according to claim 1, characterized in that: The inlet air temperature of the spray drying in step (5) is 140-180°C.

9. The method for preparing Zanthoxylum bungeanum seed oil microcapsules according to claim 1, characterized in that: The outlet air temperature of the spray drying in step (5) is 85°C.

10. A Zanthoxylum bungeanum seed oil microcapsule prepared according to the method according to any one of claims 1 to 9.

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