A Pickering emulsion stabilized by a co-paste of cereal non-starch polysaccharide and oat starch and loaded with ferulic acid, and a preparation method thereof

Abstract

The present invention discloses a Pickering emulsion stabilized by a co-paste of cereal non-starch polysaccharide and oat starch loaded with ferulic acid and a preparation method thereof. The preparation method includes: adding a cereal non-starch polysaccharide with a molecular weight of 80-100 kDa to water, then adding oat starch thereto, and gelatinizing the mixture to obtain a co-paste of cereal non-starch polysaccharide and oat starch; preparing an aqueous phase by adding the co-paste of cereal non-starch polysaccharide and oat starch to water, preparing an oil phase by placing ferulic acid in vegetable oil, and mixing the oil phase and the aqueous phase to obtain a crude emulsion. The present invention has the characteristics of simple process, green environmental protection, and continuous industrial production, etc.; the cereal-derived non-starch polysaccharide has a significant improvement effect on the physicochemical and digestion characteristics of oat starch, and can be widely applied to the field of food industry.

Description

Technical Field

[0001] The present invention belongs to the field of deep processing of natural products and modern functional food processing, and particularly relates to a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch and a preparation method thereof. Background Art

[0002] Natural starch has been widely used in the food industry as a food thickener, fat substitute, stabilizer, and gelling agent. However, due to some undesirable properties, such as syneresis, retrogradation, pH sensitivity, and heat instability, the utilization of natural starch is often limited. To eliminate or reduce these adverse properties, different modification methods can be used to modify natural starch, and one method is to add non-starch polysaccharides (NSPs). This method is a relatively simple and low-cost technology that can replace chemical modification or other expensive physical modifications. Many previous studies have reported that adding NSPs to starch suspensions can improve viscosity, gelling properties, water-binding capacity, emulsion stability, and prevent recrystallization, film formation, and enhance foam stability. These starch-NSPs complexes can be used in various foods, such as ketchup, mayonnaise, salad dressings, fat mimetics, and ice cream.

[0003] Oat is one of the important cultivated varieties widely planted and consumed in northern China. It has high nutritional and medicinal value and is recognized as a low glycemic index or medium glycemic index food. Starch is usually located in the oat endosperm, surrounded by β-glucan and a protein-rich bran layer, accounting for 50%-65%. Compared with other common cereal starches, oat starch has prominent structural characteristics and unique functional properties, including film-forming ability, foaming ability, emulsifying ability, and water-binding ability. However, the application of native oat starch usually still has some problems, such as low heat resistance, paste transparency, shear resistance, and increased paste viscosity. To overcome these disadvantages, physical and chemical modifications have been introduced. For example, high hydrostatic pressure (above 400 mpa) treatment destroys the crystallization of oat starch and reduces the recrystallization rate of oat starch. Subcritical ethanol-water treatment can improve the cold water swelling properties of oat starch. The present invention aims to develop cereal non-starch polysaccharides to promote the development of functional raw materials. Summary of the Invention

[0004] An object of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0005] Another object of the present invention is to provide a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch and a preparation method thereof, which has the advantages of simple and convenient preparation method, safe and controllable process, continuous production, and low-cost green production.

[0006] Therefore, the technical solution provided by the present invention is as follows:

[0007] A preparation method of Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, comprising the following steps:

[0008] 1) Prepare cereal non-starch polysaccharide and select the component with a molecular weight of 80-100 kDa;

[0009] 2) Add the cereal non-starch polysaccharide with a molecular weight of 80-100 kDa to water, and then add oat starch thereto. The material-liquid ratio of the cereal non-starch polysaccharide is 1:350-500, and the material-liquid ratio of the oat starch is 1:50-150. Then disperse the mixture at a temperature of 15-30 °C for 15-30 min, and then heat it at 90-100 °C for 15-30 min and keep stirring for gelatinization. Finally, dry it to obtain the co-paste of cereal non-starch polysaccharide and oat starch. Specifically, disperse the mixture at 15-30 °C by magnetic stirring for 15-30 min, and then heat it at 90-100 °C for 15-30 min and continuously stir to ensure complete gelation. After cooling to room temperature, freeze-dry the co-paste of cereal non-starch polysaccharide and corn starch, and collect to obtain the co-paste of whole cereal non-starch polysaccharide and oat starch.

[0010] 3) Add the co-paste of cereal non-starch polysaccharide and oat starch to water to prepare an aqueous phase, place ferulic acid in vegetable oil to prepare an oil phase, and mix the oil phase and the aqueous phase to obtain a Pickering crude emulsion loaded with ferulic acid.

[0011] Preferably, in the preparation method of the Pickering emulsion loaded with ferulic acid stabilized by the co-paste of cereal non-starch polysaccharide and oat starch, add the co-paste of cereal non-starch polysaccharide and oat starch to water to prepare a 1.5 %w / w solution, and swell it at 25 °C for a period of time, such as 6 h, and stir evenly to prepare the aqueous phase, and then perform ultrasonic modification to make the gelatinization degree of the co-paste of cereal non-starch polysaccharide and oat starch reach more than 90%; wherein, the conditions of the ultrasonic modification are: the temperature is not higher than 4 °C, the ultrasonic power is 600 W, turn on for 0.5 s and turn off for 0.5 s, and perform ultrasonic at three frequencies of 20-24 kHz, 42-46 kHz, and 66-70 kHz simultaneously, and the ultrasonic time is 5-10 min.

[0012] Preferably, in the preparation method of the Pickering emulsion loaded with ferulic acid stabilized by the co-paste of cereal non-starch polysaccharide and oat starch, in step 1), the method for preparing the cereal non-starch polysaccharide includes:

[0013] The grains are ground into powder, defatted and dried. The dried grain powder is soaked in water at a solid-liquid ratio of 20 - 45 mL / g, and then extracted using a CW-2000A ultrasonic microwave digestion extractor. The preset microwave power is 500 - 900 W, the temperature is 25 - 40 °C, the treatment time is 10 - 35 min, the pH value is 6 - 11, the microwave frequency is 2450 MHz, and the ultrasonic frequency is 40 KHz. Subsequently, the obtained product is leached at 60 - 90 °C for 1 - 3 h, and the sample is separated to obtain the supernatant. The supernatant is concentrated to 1 / 4 of the initial volume using a vacuum rotary evaporator, 3 times the volume of 95% ethanol by volume is added, and it is left to stand overnight at 4 °C. The alcohol-precipitated solution is centrifuged, and the precipitate is collected;

[0014] The precipitate is dissolved in deionized water to form a uniform polysaccharide solution, which is then transferred to an ultrafiltration device. An ultrafiltration membrane with a molecular weight cut-off of 100 kDa is selected. The peristaltic pump is turned on, and the flow rate is set to 150 - 200 mL / min, and the pressure is 0.2 - 0.3 MPa to allow the polysaccharide solution to pass through the 100 kDa ultrafiltration membrane. The permeate is collected. Then, an ultrafiltration membrane with a molecular weight cut-off of 80 kDa is selected. The peristaltic pump is turned on, and the flow rate is set to 80 - 100 mL / min, and the pressure is 0.3 - 0.4 MPa to allow the permeate to pass through the 80 kDa ultrafiltration membrane. When the solution volume is concentrated to 1 / 10 of the original volume, ultrafiltration is stopped, and the retentate is collected to obtain a preliminarily purified cereal non-starch polysaccharide solution;

[0015] The preliminarily purified cereal non-starch polysaccharide solution is subjected to dialysis treatment and then freeze-dried to obtain cereal non-starch polysaccharide.

[0016] Preferably, in the preparation method of the Pickering emulsion stably loaded with ferulic acid by the co-paste of the cereal non-starch polysaccharide and oat starch, in step 2), the mixture is heated at 90 - 100 °C for 15 - 30 min and stirred continuously until it is completely gelatinized, then cooled to room temperature, and then subjected to the drying, and the drying is carried out by freeze-drying.

[0017] Preferably, in the preparation method of the Pickering emulsion stably loaded with ferulic acid by the co-paste of the cereal non-starch polysaccharide and oat starch, in step 3), the mass ratio of the aqueous phase to the oil phase is 5 - 10 : 95 - 90.

[0018] Preferably, in the preparation method of the Pickering emulsion with ferulic acid stably loaded by the co-paste of cereal non-starch polysaccharide and oat starch, in step 3), the Pickering crude emulsion loaded with ferulic acid is homogenized at a temperature of 4 °C, a power of 750 W, turned on for 1 s and turned off for 1 s, with an amplitude of 60% for 8 min to obtain the Pickering emulsion loaded with ferulic acid. Specifically, the oil phase and the water phase are mixed at a mass ratio of 5-10:95-90, and stirred with an IKA T25 digital high-speed stirrer at 8000 rpm for 1 min and at 11000 rpm for 1 min to prepare the crude emulsion. Further, using a SONICS VCX750 ultrasonic cell disruptor in a 4 °C jacketed beaker, homogenized at a power of 750 W, turned on for 1 s and turned off for 1 s, with an amplitude of 60% for 8 min, and the emulsion sample is stored at low temperature in a brown vial.

[0019] Preferably, in the preparation method of the Pickering emulsion with ferulic acid stably loaded by the co-paste of cereal non-starch polysaccharide and oat starch, in step 3), the method for preparing the oil phase is as follows: Ferulic acid is dissolved in ethanol to a concentration of 30-60 mg / mL, and then the 30-60 mg / mL ferulic acid ethanol solution is added to the vegetable oil according to a volume ratio of 1-4:9-6. After that, ethanol is removed by heating and evaporation to prepare the oil phase, and the vegetable oil used is walnut oil. For example, ferulic acid (30-60 mg / mL) is dissolved in ethanol and stirred at 25 °C for 2 h to ensure complete dissolution, and then added to walnut oil according to a volume ratio of 1-4:9-6, and stirred at 85 °C for 30 min to evaporate ethanol to prepare the oil phase.

[0020] Preferably, in the preparation method of the Pickering emulsion with ferulic acid stably loaded by the co-paste of cereal non-starch polysaccharide and oat starch, in step 1), the cereal is ground into powder and passed through a 50-mesh sieve, and the material under the sieve is defatted twice with petroleum ether. The solid-liquid ratio during each defatting is 1:10, and the defatting time is 3 h each time. Then, the precipitate is centrifuged and dried.

[0021] Preferably, in the preparation method of the Pickering emulsion with ferulic acid stably loaded by the co-paste of cereal non-starch polysaccharide and oat starch, the cereal is at least one of oat, oat germ rice, black rice, purple rice, fragrant rice, millet, red rice or coix seed.

[0022] A Pickering emulsion with ferulic acid stably loaded by the co-paste of cereal non-starch polysaccharide and oat starch, which is prepared by the method described in any one of the above.

[0023] The present invention has at least the following beneficial effects:

[0024] In the present invention, a Pickering emulsion in which a co-paste of cereal non-starch polysaccharide and oat starch stably loads ferulic acid and a preparation method thereof are provided, including: extracting non-starch polysaccharide in cereals by ultrasonic microwave-assisted and hot water extraction, and obtaining the cereal non-starch polysaccharide by alcohol precipitation; obtaining a co-paste of cereal non-starch polysaccharide and oat starch by heating co-pasting treatment to achieve the modification effect on oat starch. Dissolving ferulic acid in walnut oil as the oil phase and using the co-paste solution of non-starch polysaccharide and oat starch as the water phase, and performing homogenization treatment based on a high-speed blender and an ultrasonic cell disruptor to obtain a Pickering emulsion in which a co-paste of cereal non-starch polysaccharide and oat starch stably loads ferulic acid, which can be used as a substrate for food, beverage, cosmetics or for fermentation or chemical modification. The present invention has the characteristics of simple process, green environmental protection, and continuous industrial production; the cereal-derived non-starch polysaccharide has a significant improvement effect on the physical and chemical and digestion characteristics of oat starch, and can be widely applied to the field of food industry.

[0025] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and will also be understood by those skilled in the art through the research and practice of the present invention. Description of the Drawings

[0026] Figure 1 It is a comparison chart of the swelling power of the co-paste of polysaccharide and oat starch in each group in the present invention.

[0027] Figure 2 It is a comparison chart of the solubility of the co-paste of polysaccharide and oat starch in each group in the present invention.

[0028] Figure 3 It is a comparison chart of the leached amylose content of the co-paste of polysaccharide and oat starch in each group in the present invention.

[0029] Figure 4 It is a comparison chart of the digestion characteristics of the co-paste of polysaccharide and oat starch in each group in the present invention.

[0030] Figure 5 It is a ferulic acid encapsulation efficiency chart of the Pickering emulsion in which a co-paste of polysaccharide and oat starch in each group in the present invention stably loads ferulic acid.

[0031] Figure 6 It is a ferulic acid release efficiency chart of the Pickering emulsion in which a co-paste of polysaccharide and oat starch in each group in the present invention stably loads ferulic acid in simulated in vitro digestion. Detailed Embodiments

[0032] The following further describes the present invention in detail with reference to the accompanying drawings, so that those skilled in the art can implement it according to the text of the specification.

[0033] It should be understood that terms such as "having", "comprising", and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0034] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial sources unless otherwise specified.

[0035] The original non-starch components (NSCs) present in grains, including proteins, lipids, and β-glucans, have a great impact on the digestibility of oat starch. Grains such as rice, purple rice, black rice, coix seed, etc. are widely cultivated crops, and the non-starch polysaccharides they contain are important carbohydrate components, but they have not been fully developed and applied. In addition, ferulic acid is a hydrocinnamic acid with strong antioxidant, anti-inflammatory, anti-cancer, and antiviral properties. It has also been used as a candidate drug for treating diseases such as diabetes, cancer, Alzheimer's disease, skin diseases, and cardiovascular diseases. It has been approved by the US Food and Drug Administration and used as a preservative to prevent the auto-oxidation of oils. However, it is prone to photodegradation and degradation when exposed to oxygen. Therefore, in order to extend the shelf life, improve the release rate and utilization rate of ferulic acid in digestion, using a Pickering emulsion stabilized by cereal non-starch polysaccharides and oat starch as a delivery carrier for ferulic acid may be a good research field. So far, there have been few reports on the effects of cereal-derived NSPs on the structure and physicochemical properties of oat starch, as well as the development and application research of Pickering emulsions stabilized by cereal non-starch polysaccharides and oat starch. Based on the above technical deficiencies, the present invention provides a method for co-pasting cereal-derived polysaccharides and oat starch with good swelling power and solubility and capable of assisting slow digestion, which is of great significance for promoting the development of functional raw materials.

[0036] To enable those skilled in the art to better understand the technical solution of the present invention, the following further description is provided:

[0037] Example 1

[0038] The dried fragrant rice was ground into powder using a laboratory mill and sieved through a 50-mesh sieve. It was defatted twice with petroleum ether for 3 h at room temperature, with a solid-liquid ratio of 1:10 for each step. The mixture was centrifuged at 3000 × g for 15 min (H-2050R, Xiangyi, China) and then dried in a fume hood for 48 h. After drying, the powder was soaked in distilled water with a solid-liquid ratio of 1∶25. Then, extraction was carried out using a CW-2000A ultrasonic microwave digestion extractor with a preset microwave power of 800 W, temperature of 40 °C, treatment time of 30 min, and pH value of 6.0. The microwave frequency was 2450 MHz and the ultrasonic frequency was 40 KHz. Subsequently, the above-obtained product was placed in a constant temperature water bath and extracted at 80 °C for 2 h. The sample was centrifuged at 8500 rpm for 10 min to obtain the supernatant and precipitate. The supernatant was taken and concentrated to 1 / 4 of the initial volume using a vacuum rotary evaporator (60 °C), 4 times the volume of 95% ethanol was added, and it was left to stand overnight at 4 °C. The alcohol-precipitated solution was centrifuged at 8500 rpm for 10 min, and the precipitate was collected. The precipitate was dissolved in deionized water to form a uniform polysaccharide solution, which was transferred to an ultrafiltration device. An ultrafiltration membrane with a molecular weight cut-off of 100 kDa was selected. The peristaltic pump was turned on, the flow rate was set to 1750 mL / min, and the pressure was 0.25 MPa to allow the polysaccharide solution to pass through the 100 kDa ultrafiltration membrane. The permeate was collected, and then an ultrafiltration membrane with a molecular weight cut-off of 80 kDa was selected. The peristaltic pump was turned on, the flow rate was set to 90 mL / min, and the pressure was 0.35 MPa to allow the permeate to pass through the 80 kDa ultrafiltration membrane. When the solution volume was concentrated to 1 / 10 of the original volume, ultrafiltration was stopped, and the retentate was collected to obtain a preliminarily purified cereal non-starch polysaccharide solution;

[0039] The preliminarily purified cereal non-starch polysaccharide solution was subjected to dialysis treatment and then freeze-dried (-60 °C) to obtain fragrant rice non-starch polysaccharide.

[0040] The fragrant rice non-starch polysaccharide was dissolved in distilled water, and then oat starch was added to each solution. The solid-liquid ratio of fragrant rice non-starch polysaccharide was 1:350, and the solid-liquid ratio of oat starch was 1:50. The mixture was dispersed by magnetic stirring at 25 °C for 30 min and then heated at 90 °C for 30 min with continuous stirring to ensure complete gelation. After cooling to room temperature, the co-paste of fragrant rice non-starch polysaccharide and oat starch was freeze-dried, and the fragrant rice non-starch polysaccharide-oat starch co-paste was collected.

[0041] Dissolve ferulic acid (50 mg / mL) in ethanol, stir at 25 °C for 2 h to ensure complete dissolution, add it to walnut oil according to a volume ratio of 1:9, and stir at 85 °C for 30 min to evaporate ethanol to prepare the oil phase. Dissolve the co-paste of fragrant rice non-starch polysaccharide - oat starch in ultrapure water to prepare a 1.5 % w / w solution, swell it at 25 °C for 6 h, stir evenly to prepare the water phase, and then perform ultrasonic modification until the gelatinization degree of the co-paste of cereal non-starch polysaccharide - oat starch reaches 95%; wherein, the conditions for the ultrasonic modification are: the temperature is not higher than 4 °C, the ultrasonic power is 600 W, it is turned on for 0.5 s and turned off for 0.5 s, and ultrasonic waves are carried out simultaneously at three frequencies of 22 kHz, 44 kHz, and 68 kHz, and the ultrasonic time is 8 min. Then, mix the oil phase and the water phase according to a mass ratio of 5:95, and use an IKA T25 digital high-speed stirrer to stir at 8000 rpm for 1 min and at 11000 rpm for 1 min to prepare a crude emulsion. Further use a SONICS VCX750 ultrasonic cell disruptor in a 4 °C jacketed beaker, with a power of 750 W, turned on for 1 s and turned off for 1 s, and an amplitude of 60%, and continuously homogenize for 8 min, and store the emulsion sample at low temperature in a brown vial.

[0042] Example 2

[0043] The dried millet was ground into powder using a laboratory mill and sieved through a 50-mesh sieve. It was defatted twice with petroleum ether for 3 h at room temperature, with a solid-liquid ratio of 1:10 for each step. The mixture was centrifuged at 3000 × g for 15 min (H-2050R, Xiangyi, China) and then dried in a fume hood for 48 h. After drying, the powder was soaked in distilled water with a solid-liquid ratio of 1∶45. Then, extraction was carried out using a CW-2000A ultrasonic microwave digestion extractor with a preset microwave power of 900 W, temperature of 40 °C, treatment time of 30 min, and pH value of 6.0. The microwave frequency was 2450 MHz and the ultrasonic frequency was 40 KHz. Subsequently, the above-obtained product was placed in a constant temperature water bath and extracted at 90 °C for 2 h. The sample was centrifuged at 8500 rpm for 10 min to obtain the supernatant and precipitate. The supernatant was taken and concentrated to 1 / 4 of the initial volume using a vacuum rotary evaporator (60 °C), 3 volumes of 95% ethanol were added, and it was left to stand overnight at 4 °C. The alcohol-precipitated solution was centrifuged at 8500 rpm for 10 min, and the precipitate was collected. The precipitate was dissolved in deionized water to form a uniform polysaccharide solution, which was transferred to an ultrafiltration device. An ultrafiltration membrane with a molecular weight cut-off of 100 kDa was selected. The peristaltic pump was turned on, the flow rate was set to 150 mL / min, and the pressure was 0.2 MPa to allow the polysaccharide solution to pass through the 100 kDa ultrafiltration membrane. The permeate was collected, and then an ultrafiltration membrane with a molecular weight cut-off of 80 kDa was selected. The peristaltic pump was turned on, the flow rate was set to 80 mL / min, and the pressure was 0.3 MPa to allow the permeate to pass through the 80 kDa ultrafiltration membrane. When the solution volume was concentrated to 1 / 10 of the original volume, ultrafiltration was stopped, and the retentate was collected to obtain a preliminarily purified cereal non-starch polysaccharide solution;

[0044] The preliminarily purified cereal non-starch polysaccharide solution was dialyzed and then freeze-dried (-60 °C) to obtain millet non-starch polysaccharide.

[0045] The millet non-starch polysaccharide was dissolved in distilled water, and then oat starch was added to each solution. The solid-liquid ratio of millet non-starch polysaccharide was 1:500, and the solid-liquid ratio of oat starch was 1:150. The mixture was dispersed by magnetic stirring at 25 °C for 30 min and then heated at 100 °C for 30 min with continuous stirring to ensure complete gelation. After cooling to room temperature, the co-paste of millet non-starch polysaccharide and oat starch was freeze-dried, and the millet non-starch polysaccharide-oat starch co-paste was collected.

[0046] Ferulic acid (60 mg / mL) was dissolved in ethanol and stirred at 25 °C for 2 h to ensure complete dissolution. Then it was added to walnut oil at a volume ratio of 1:9 and stirred at 85 °C for 30 min to evaporate the ethanol and prepare the oil phase. The millet non-starch polysaccharide-oat starch co-paste was dissolved in ultrapure water to prepare a 1.5 % w / w solution, which was swollen at 25 °C for 6 h and stirred evenly to prepare the water phase. Then it was ultrasonically modified to make the gelatinization degree of the cereal non-starch polysaccharide-oat starch co-paste reach more than 90%. The conditions of the ultrasonic modification were as follows: the temperature was not higher than 4 °C, the ultrasonic power was 600 W, it was turned on for 0.5 s and off for 0.5 s, and ultrasonic waves were carried out simultaneously at three frequencies of 24 kHz, 42 kHz, and 66 kHz for 10 min. Then, the oil phase and the water phase were mixed at a mass ratio of 1:9 and stirred with an IKA T25 digital high-speed mixer at 8000 rpm for 1 min and 11000 rpm for 1 min to prepare a crude emulsion. Further, a SONICS VCX750 ultrasonic cell disruptor was used in a 4 °C jacketed beaker at a power of 750 W, turned on for 1 s and off for 1 s, with an amplitude of 60%, and continuously homogenized for 8 min. The emulsion sample was stored at low temperature in a brown vial.

[0047] Example 3

[0048] The dried purple rice was ground into powder using a laboratory mill and sieved through a 50-mesh sieve. It was defatted twice with petroleum ether for 3 h at room temperature, with a solid-liquid ratio of 1:10 in each step. The mixture was centrifuged at 3000 × g for 15 min (H-2050R, Xiangyi, China) and then dried in a fume hood for 48 h. After drying, the powder was soaked in distilled water with a solid-liquid ratio of 1∶30. Then, extraction was carried out using a CW-2000A ultrasonic microwave digestion extractor with a preset microwave power of 900 W, temperature of 40 °C, treatment time of 30 min, and pH value of 6.0. The microwave frequency was 2450 MHz and the ultrasonic frequency was 40 KHz. Subsequently, the above-obtained product was placed in a constant temperature water bath and extracted at 80 °C for 2 h. The sample was centrifuged at 8500 rpm for 10 min to obtain the supernatant and precipitate. The supernatant was taken and concentrated to 1 / 4 of the initial volume using a vacuum rotary evaporator (60 °C), 3 volumes of 95% ethanol were added, and it was left to stand overnight at 4 °C. The alcohol-precipitated solution was centrifuged at 8500 rpm for 10 min, and the precipitate was collected. The precipitate was dissolved in deionized water to form a uniform polysaccharide solution, which was transferred to an ultrafiltration device. An ultrafiltration membrane with a molecular weight cut-off of 100 kDa was selected. The peristaltic pump was turned on, the flow rate was set to 200 mL / min, and the pressure was 0.3 MPa to allow the polysaccharide solution to pass through the 100 kDa ultrafiltration membrane. The permeate was collected, and then an ultrafiltration membrane with a molecular weight cut-off of 80 kDa was selected. The peristaltic pump was turned on, the flow rate was set to 100 mL / min, and the pressure was 0.4 MPa to allow the permeate to pass through the 80 kDa ultrafiltration membrane. When the solution volume was concentrated to 1 / 10 of the original volume, ultrafiltration was stopped, and the retentate was collected to obtain a preliminarily purified cereal non-starch polysaccharide solution;

[0049] The preliminarily purified cereal non-starch polysaccharide solution was dialyzed and then freeze-dried (-60 °C) to obtain purple rice non-starch polysaccharide.

[0050] The purple rice non-starch polysaccharide was dissolved in distilled water, and then oat starch was added to each solution. The solid-liquid ratio of purple rice non-starch polysaccharide was 1:400, and the solid-liquid ratio of oat starch was 1:100. The mixture was dispersed by magnetic stirring at 25 °C for 30 min and then heated at 100 °C for 30 min with continuous stirring to ensure complete gelation. After cooling to room temperature, the purple rice non-starch polysaccharide and oat starch co-paste was freeze-dried, and the purple rice non-starch polysaccharide-oat starch co-paste was collected.

[0051] Dissolve ferulic acid (30 mg / mL) in ethanol and stir for 2 h at 25 °C to ensure complete dissolution. Add it to walnut oil according to a volume ratio of 1:4 and stir at 85 °C for 30 min to evaporate ethanol and prepare the oil phase. Dissolve the millet non-starch polysaccharide-oat starch co-paste in ultrapure water to prepare a 1.5 % w / w solution, swell it at 25 °C for 6 h, stir evenly to prepare the water phase, and then perform ultrasonic modification to make the gelatinization degree of the cereal non-starch polysaccharide-oat starch co-paste reach more than 90%. The conditions for the ultrasonic modification are: the temperature is not higher than 4 °C, the ultrasonic power is 600 W, it is turned on for 0.5 s and off for 0.5 s, and ultrasonic waves are carried out simultaneously at three frequencies of 20 kHz, 46 kHz, and 70 kHz for 5 min. Then, mix the oil phase and the water phase according to a mass ratio of 1:9 and use an IKA T25 digital high-speed mixer to stir at 8000 rpm for 1 min and 11000 rpm for 1 min to prepare a crude emulsion. Further use a SONICS VCX750 ultrasonic cell disruptor in a 4 °C jacketed beaker, with a power of 750 W, turned on for 1 s and off for 1 s, an amplitude of 60%, and continuously homogenize for 8 min. Store the emulsion sample at low temperature in a brown vial.

[0052] Example 4

[0053] A method for preparing a Pickering emulsion stabilized by a co-paste of cereal non-starch polysaccharide and oat starch and loaded with ferulic acid, the steps are the same as in Example 1, except that the cereal non-starch polysaccharide is black rice polysaccharide.

[0054] Example 5

[0055] A method for preparing a Pickering emulsion stabilized by a co-paste of cereal non-starch polysaccharide and oat starch and loaded with ferulic acid, the steps are the same as in Example 1, except that the cereal non-starch polysaccharide is red rice polysaccharide.

[0056] Example 6

[0057] A method for preparing a Pickering emulsion stabilized by a co-paste of cereal non-starch polysaccharide and oat starch and loaded with ferulic acid, the steps are the same as in Example 1, except that the cereal non-starch polysaccharide is coix seed polysaccharide.

[0058] Example 7

[0059] A method for preparing a Pickering emulsion stabilized by a co-paste of cereal non-starch polysaccharide and oat starch and loaded with ferulic acid, the steps are the same as in Example 1, except that the cereal non-starch polysaccharide is oat germ rice polysaccharide.

[0060] Comparative Example 1

[0061] A preparation method of a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, the steps are the same as those in Example 1, except that oat starch is used alone for gelatinization treatment.

[0062] Comparative Example 2

[0063] A preparation method of a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, the steps are the same as those in Example 1, except that only fragrant rice polysaccharide is used as an emulsifier to prepare the Pickering emulsion loaded with ferulic acid.

[0064] Comparative Example 3

[0065] A preparation method of a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, the steps are the same as those in Example 1, except that the cereal non-starch polysaccharide and oat starch are directly mixed without gelatinization treatment.

[0066] Comparative Example 4

[0067] A preparation method of a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, the steps are the same as those in Example 1, except that the mushroom non-starch polysaccharide is lentinan.

[0068] Comparative Example 5

[0069] A preparation method of a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, the steps are the same as those in Example 1, except that the extraction of cereal non-starch polysaccharide does not adopt ultrasonic-microwave assisted extraction.

[0070] Comparative Example 6

[0071] A preparation method of a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, the steps are the same as those in Example 1, except that for the extraction of cereal non-starch polysaccharide, the ultrasonic wave uses a preset microwave power of 400 W, a temperature of 60 °C, a treatment time of 40 min, and a pH value of 4.0, and the material-liquid ratio of cereal powder to water is 1:10.

[0072] Comparative Example 7

[0073] A preparation method of a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, the steps are the same as those in Example 1, except that during the co-gelatinization treatment, the cereal non-starch polysaccharide and oat starch are heated at 80 °C for 40 min with continuous stirring.

[0074] Comparative Example 8

[0075] A method for preparing a Pickering emulsion loaded with ferulic acid stabilized by a co-paste of cereal non-starch polysaccharide and oat starch, the steps are the same as in Example 1, except that it is treated under the condition of 600 bar by a SCIENTZ-150 high-pressure homogenizer to form a Pickering emulsion loaded with ferulic acid.

[0076] Determination of swelling power and solubility of co-paste of cereal non-starch polysaccharide and oat starch

[0077] Soak 2% of the sample (w / w) in 30 mL of deionized water and place it in a weighing tube. After heating at a constant temperature of 95 °C for 30 min, centrifuge the suspension for 20 min (3000×g), collect the supernatant, and weigh the precipitate. The supernatant is dried to a constant weight in an oven at 105 °C. The following equations are used to calculate the swelling power and solubility.

[0078]

[0079]

[0080] The swelling power and solubility can characterize the water absorption capacity of starch granules and the degree of amylose leaching during the swelling process. Figure 1 and Figure 2 respectively show the effects of polysaccharide type, polysaccharide extraction method, and co-pasting treatment method on the swelling power and solubility of the co-paste of cereal non-starch polysaccharide and oat starch. Compared with pure oat starch (Control 1) and non-gelatinized treatment (Control 3), the co-pasting treatment with the addition of cereal non-starch polysaccharide has a significant modification effect on oat starch. Compared with mushroom non-starch polysaccharide (Control 4), the swelling power and solubility of the co-paste of cereal non-starch polysaccharide and oat starch are significantly better than those of the co-paste of mushroom non-starch polysaccharide and oat starch, indicating that the co-pasting treatment of cereal non-starch polysaccharide and oat starch shows a better modification effect. In addition, the cereal non-starch polysaccharide obtained by ultrasonic microwave-assisted extraction has a better effect on enhancing the swelling power and solubility of the co-paste than the cereal non-starch polysaccharide without ultrasonic microwave-assisted extraction (Control 5), which may be closely related to the fact that ultrasonic microwave-assisted extraction can affect the structure and physicochemical properties of polysaccharides, and different ultrasonic microwave treatment conditions (Control 6) have different effects on the properties of polysaccharides. It should be noted that the gelatinization temperature is also an important factor affecting the properties of the co-paste of cereal non-starch polysaccharide and oat starch (Control 7), and a higher temperature can make the modification effect of cereal non-starch polysaccharide on oat starch better, and thus make its co-paste have higher swelling power and solubility.

[0081] Determination of amylose leaching of co-paste of cereal non-starch polysaccharide and oat starch

[0082] The content of amylose leached from the sample was measured by the iodine colorimetric method. Weighed the freeze-dried sample (10 mg) in a centrifuge tube, added 1.0 mL of 0.2 M NaOH solution to extract amylose, incubated in a water bath at 95 °C for 30 min, then stained with I2-KI solution and measured at 620 nm. Using potato amylose as the standard, the calibration curve equation (A 620 = 0.9315 C + 0.0133, R 2 = 0.9987, where C is the amylose concentration) was obtained. The absorbance value of 0.2 M NaOH solution at 620 nm was used as the blank.

[0083]

[0084] Where OD sam is the absorbance value of the sample, OD ctrl is the absorbance value of the blank; V is the volume of the extraction solution (mL); W is the weight of the sample (g).

[0085] The two main components of starch are amylose and amylopectin, which have significant differences in properties and functions. Amylose has a high tendency to retrograde, producing hard gels and hard films. In contrast, amylopectin dispersed in water is more stable, producing soft gels and weak films. During the gelatinization process, the crystal structure of starch is destroyed, the granules continue to swell, and amylose penetrates into the aqueous phase between the granules. In Figure 3 , the content of amylose leached from the co-paste of mushroom non-starch polysaccharide (Comparative Example 4), cereal non-starch polysaccharide (Comparative Examples 3, 5-7, Examples 1-7) and oat starch was significantly higher than that of the oat starch paste alone (Comparative Example 1). It was found by comparison that the modification effect of cereal non-starch polysaccharide on oat starch without ultrasonic microwave-assisted treatment was not significant, and the ultrasonic microwave-assisted treatment conditions and co-pasting temperature would affect the modification effect of cereal non-starch polysaccharide on oat starch.

[0086] Determination of the digestion characteristics of the co-paste of cereal non-starch polysaccharide and oat starch

[0087] Suspend the sample (200 mg) in 15 mL of 0.2 M sodium acetate buffer (pH 5.2) in a 50 mL centrifuge tube. Then, add a mixed enzyme solution (5 mL) of porcine pancreatic α-amylase (300 U / mL) and amyloglucosidase (20 U / mL) to the starch suspension. Incubate the mixture at 37 °C and stir at 200 rpm in a water bath. Extract equal amounts (100 μL) of the hydrolyzate at 0, 20, and 120 min and immediately mix with 900 μL of absolute ethanol to inactivate the enzyme. After centrifuging for 3 min, measure the glucose released from the sample using a glucose oxidase kit (oxidase-peroxidase kit, Rongsheng Biotechnology Co., Ltd., Shanghai, China). Calculate the contents of rapidly digestible starch (RDS, hydrolyzed after 20 min), slowly digestible starch (SDS, hydrolyzed after another 100 min), and resistant starch (RS, not hydrolyzed after 120 min) using the following equations:

[0088]

[0089]

[0090]

[0091] where TS is the weight (mg) of the total starch content. G 0 、G 20 、G 120 represent the glucose contents in the chyme at 0, 20, and 120 min, respectively. The conversion ratio of digested starch to glucose is 0.9.

[0092] The comparison chart of the digestion characteristics of the co-paste of the polysaccharide and oat starch in each group of the present invention is shown in Figure 4。Compared with the single oat starch paste (Comparative Example 1), the RDS content of Examples 1-7 decreased sharply by 46.82%, 47.39%, 45.81%, 49.03%, 47.65%, 49.32% and 48.72% respectively from 55.95% of OS. On the contrary, the RS level increased. It is worth noting that there was no significant difference in the SDS of Comparative Examples 4 and 6 compared with that of Comparative Example 1, and there was a certain increasing trend in the SDS of Comparative Examples 3, 5 and 7. Therefore, cereal non-starch polysaccharides have an obvious inhibitory effect on the digestion of oat starch, which may contribute to blood glucose control. In vitro digestive systems usually contain enzymes, starch and non-starch components (NSCs). The interactions between these chemicals may all affect starch digestion. The inhibition of digestion by non-starch components (NSCs) may be attributed to several reasons. First, NSCs can form physical barriers such as membranes around starch molecules, thereby reducing the affinity between digestive enzymes and substrates and reducing the accessibility of enzymes. Second, the molecular entanglement and overlap induced by NSCs and starch, as well as the self-assembly behavior of NSCs in water, significantly increase the viscosity of the reaction mixture, thereby restricting the mobility of water and reducing the release and diffusion of starch hydrolysis products (including glucose). Third, the molecular adsorption between NSCs and hydrolases may promote the reduction of starch digestion rate due to its non-competitive inhibition reaction. Finally, the strengthening of the microstructure of the composite gel may be due to the interaction between biopolymers, resulting in a decrease in starch digestion with the increase in the addition amount of NSPs.

[0093] Determination of the encapsulation efficiency of ferulic acid in Pickering emulsions stabilized by co-pastes of cereal non-starch polysaccharides and oat starch

[0094] The sample was demulsified with methanol to recover the entrapped ferulic acid. Briefly, 1 mL of methanol was added to 200 μL of the sample, vortexed for 2 min and centrifuged at 8500 rpm for 10 min. To determine the ferulic acid content in the Pickering emulsion sample, 800 μL of the supernatant was added to 200 μL of methanol, kept at 250 rpm on a magnetic stirrer for 6 h, centrifuged again at 8500 rpm for 10 min, the supernatant was collected, and its absorbance was measured at 321 nm by spectrophotometry to determine the ferulic acid encapsulation efficiency.

[0095]

[0096] wherein, FA 释放 is the content of ferulic acid released from Pickering emulsion particles, and FA 添加 is the initial addition amount of ferulic acid.

[0097] The comparison chart of the digestion characteristics of the co-pastes of each group of polysaccharides and oat starch of the present invention is shown in Figure 5。Compared with Comparative Example 4, it can be seen that the Pickering emulsion stabilized by the co-paste of cereal non-starch polysaccharide and oat starch has significantly better ferulic acid encapsulation efficiency than the Pickering emulsion stabilized by the co-paste of lentinan and oat starch. In addition, non-gelatinization treatment and gelatinization treatment conditions affect the emulsifying properties of the co-paste of cereal non-starch polysaccharide and oat starch, and thus affect the stability of its Pickering emulsion. Compared with ultrasonic treatment (Examples 1-7), the Pickering stability prepared based on the high-pressure homogenization treatment method (Comparative Example 8) is inferior to that of ultrasonic dispersion and homogenization treatment. In addition, the cereal non-starch polysaccharide extracted without ultrasonic microwave assistance (Comparative Example 5) is not conducive to enhancing the emulsifying stability of the co-paste of cereal non-starch polysaccharide and oat starch.

[0098] Determination of the release rate of ferulic acid in the Pickering emulsion loaded with ferulic acid stabilized by the co-paste of cereal non-starch polysaccharide and oat starch during in vitro digestion

[0099] Add 10 mL of phosphate buffer solution (PBS, pH 7.2) containing α-amylase to 10 mg of the sample. Incubate the reaction mixture in a shaking water bath at 37 °C for 5 min, then centrifuge at 5500 rpm for 10 min, and record the absorbance of the supernatant at 321 nm. Treat the recovered sample with 10 mL of simulated gastric fluid (3 g / L pepsin, 8.5 g / L sterile NaCl solution, 1.0 mol / L HCl to adjust the pH to 1.6), incubate the reaction mixture at 37 °C, centrifuge at 5500 rpm for 10 min, and record the absorbance of the supernatant at 321 nm at 60-min intervals to determine the content of ferulic acid released after simulated gastric conditions (SGD). In the next stage, treat the particles with 10 mL of simulated intestinal fluid (3 g / L bile salt, 10 g / L pancreatin dissolved in phosphate buffer solution at pH 7.5), and record the absorbance after digestion for 120 min at 321 nm to determine the content of ferulic acid released after simulated intestinal digestion (SID).

[0100] The comparison chart of the digestion characteristics of the co-paste of each polysaccharide and oat starch of the present invention is shown in Figure 6Compared with the separate oat non-starch polysaccharides (Comparative Example 1), or separate cereal non-starch polysaccharides (Comparative Example 2), and the complex of ungelatinized cereal non-starch polysaccharides and oat starch (Comparative Example 3), the Pickering emulsion loaded with ferulic acid stabilized by the co-gelatinized product of cereal non-starch polysaccharides and oat starch can better achieve the surrounding effect in gastrointestinal digestion and increase the release and absorption of ferulic acid in the intestine (Examples 1-7). It should be noted that the gelatinization treatment method (Comparative Examples 3, 7) has a significantly stronger effect on the sustained-release effect of the co-gelatinized product of cereal non-starch polysaccharides and oat starch in in vitro digestion than other treatment methods (Comparative Examples 1-2, 4-6).

[0101] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the embodiments of the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the embodiments of the present invention are not limited to the specific details and the examples shown and described herein.

Claims

1. A method for preparing a Pickering emulsion loaded with ferulic acid stabilized by co-gelatinization of cereal non-starch polysaccharides and oat starch, characterized in that: The steps include: 1) Prepare cereal non-starch polysaccharides, and select components with a molecular weight of 80-100 kDa; the preparation method comprises: soaking the dried cereal powder in water at a liquid-to-solid ratio of 20-45 mL / g, and then extracting it using an ultrasonic microwave digestion extractor, wherein the microwave power is 500-900 W, the temperature is 25-40°C, the processing time is 10-35 min, the pH value is 6-11, the microwave frequency is 2450 MHz, and the ultrasonic frequency is 40 KHz; then, the obtained product is extracted at 60-90°C for 1-3 h, the sample is separated to obtain the supernatant, and the supernatant is concentrated and precipitated with alcohol; the precipitate is dissolved in deionized water, ultrafiltered, dialyzed, and freeze-dried to obtain the cereal non-starch polysaccharide; 2) adding a cereal non-starch polysaccharide with a molecular weight of 80-100 kDa to water, and then adding oat starch thereto, the solid-liquid ratio of the cereal non-starch polysaccharide is 1:350-500, and the solid-liquid ratio of the oat starch is 1:50-150, and then dispersing the mixture at a temperature of 15-30°C for 15-30 min, and then heating at 90-100°C for 15-30 min and stirring for gelatinization, and finally freeze-drying to obtain a cereal non-starch polysaccharide-oat starch co-gelatinized product; 3) Adding the cereal non-starch polysaccharide-oat starch co-gelatinized product to water to prepare an aqueous phase, and then subjecting the product to ultrasonic modification so that the degree of gelatinization of the cereal non-starch polysaccharide-oat starch co-gelatinized product reaches more than 90%; wherein the conditions for the ultrasonic modification are: temperature not higher than 4°C, ultrasonic power 600 W, 0.5 second on, 0.5 second off, 20-24 kHz, 42-46 kHz, 66-70 kHz three-frequency ultrasound simultaneously, and ultrasonic time 5-10 min; placing ferulic acid in vegetable oil to prepare an oil phase, mixing the oil phase and the aqueous phase to obtain a Pickering crude emulsion loaded with ferulic acid, and then continuously homogenizing for 8 min at a temperature of 4°C, a power of 750 W, 1 second on, 1 second off, and an amplitude of 60% to obtain a Pickering emulsion loaded with ferulic acid.

2. The method for preparing the Pickering emulsion loaded with ferulic acid stabilized by the co-gelatinization product of cereal non-starch polysaccharide and oat starch according to claim 1, characterized in that: In step 3), the cereal non-starch polysaccharide-oat starch co-gelatinized product is added to water to prepare a 1.5% w / w solution, and the solution is swollen at 25° C. for a period of time, stirred evenly to prepare the aqueous phase, and then subjected to ultrasonic modification.

3. The method for preparing the Pickering emulsion loaded with ferulic acid stabilized by the co-gelatinization product of cereal non-starch polysaccharide and oat starch according to claim 1, characterized in that: In step 1), the method for preparing cereal non-starch polysaccharides comprises: Grind the grains into powder, defatted and dried, prepare the dried grain powder into the supernatant, concentrate the supernatant to 1 / 4 of the initial volume using a vacuum rotary evaporator, add 3 times the volume of 95% ethanol, stand at 4°C overnight, centrifuge the alcohol precipitate, and collect the precipitate; The precipitate was dissolved in deionized water to prepare a uniform polysaccharide solution, and then transferred to an ultrafiltration device, an ultrafiltration membrane with a molecular weight cutoff of 100 kDa was selected, a peristaltic pump was turned on, a flow rate of 150-200 mL / min and a pressure of 0.2-0.3 MPa were set, and the polysaccharide solution passed through the 100 kDa ultrafiltration membrane, and the permeate was collected. Then, an ultrafiltration membrane with a molecular weight cutoff of 80 kDa was selected, a peristaltic pump was turned on, a flow rate of 80-100 mL / min and a pressure of 0.3-0.4 MPa were set, and the permeate passed through the 80 kDa ultrafiltration membrane. When the solution volume was concentrated to 1 / 10 of the original volume, the ultrafiltration was stopped, and the retentate was collected to obtain a preliminarily purified cereal non-starch polysaccharide solution; The preliminarily purified cereal non-starch polysaccharide solution is dialyzed and then freeze-dried to obtain the cereal non-starch polysaccharide.

4. The method for preparing the Pickering emulsion loaded with ferulic acid stabilized by the co-gelatinization product of cereal non-starch polysaccharide and oat starch according to claim 1, characterized in that: In step 2), the mixture is heated at 90-100° C. for 15-30 min and stirred until it is completely gelled, then cooled to room temperature, and then dried, wherein the drying is performed by freeze drying.

5. The method for preparing the Pickering emulsion loaded with ferulic acid stabilized by the co-gelatinization product of cereal non-starch polysaccharide and oat starch according to claim 1, characterized in that: In step 3), the mass ratio of the water phase to the oil phase is 5-10:95-90.

6. The method for preparing the Pickering emulsion loaded with ferulic acid stabilized by the co-gelatinization product of cereal non-starch polysaccharide and oat starch according to claim 1, characterized in that: In step 3), the method for preparing the oil phase is: dissolving ferulic acid in ethanol to make its concentration 30-60 mg / mL, then adding 30-60 mg / mL of ferulic acid ethanol solution to the vegetable oil in a volume ratio of 1-4:9-6, and then heating and evaporating to remove ethanol to prepare the oil phase, wherein the vegetable oil is walnut oil.

7. The method for preparing the Pickering emulsion loaded with ferulic acid stabilized by the co-gelatinization product of cereal non-starch polysaccharide and oat starch as claimed in claim 3, characterized in that: In step 1), the grains are ground into powder and then passed through a 50-mesh sieve to obtain the sieve residue, which is then defatted twice with petroleum ether; the solid-liquid ratio is 1:10 for each defatting, and the defatting time is 3 hours. The precipitate is then centrifuged and dried.

8. The method for preparing the Pickering emulsion loaded with ferulic acid stabilized by the co-gelatinization product of cereal non-starch polysaccharide and oat starch according to claim 1, characterized in that: The cereal is at least one of oats, oat germ rice, black rice, purple rice, fragrant rice, millet, red rice or coix seed.

9. A Pickering emulsion loaded with ferulic acid stabilized by co-gelatinization of cereal non-starch polysaccharides and oat starch, characterized in that: It is prepared by the method according to any one of claims 1 to 8.

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