Curcumin-loaded oat protein gel suitable for 3D printing and preparation method thereof

Abstract

The invention discloses a preparation method of oat protein gel capable of loading curcumin and suitable for 3D printing, and belongs to the field of food industry. The method comprises the following steps: (1) extracting oat protein by taking naked oat as a raw material; and (2) taking oat protein and carrageenan as raw materials, respectively dissolving the oat protein and the carrageenan in water to prepare solutions, dropwise adding the curcumin solution into the protein solution, uniformly mixing, uniformly mixing the oat protein-curcumin solution with the carrageenan solution, and cooling to obtain the curcumin-loaded oat protein gel system. And (3) carrying out 3D printing by taking the curcumin-loaded oat protein gel as a raw material. The method does not need a surfactant, and is good in biological safety. The prepared gel system has high stability, can effectively improve the protection effect on bioactive substances, is suitable for 3D printing food, achieves the purposes of high-protein food processing and food structure customization, and has good prospects in the aspects of novel nutrient substance delivery systems and food-grade 3D printing.

Description

Technical field:

[0001] The invention belongs to the technical field of novel food processing, and specifically relates to an oat protein gel capable of loading curcumin and suitable for 3D printing, and a preparation method thereof. Background technology:

[0002] 3D printing technology is an additive manufacturing technology with the advantages of high precision, high reproducibility, and customization. It can be used to shape food for special consumer groups (such as children, the elderly, and patients). 3D printing technology can mix nutritious but low-acceptance foods with other ingredients, print out beautiful shapes, and improve the acceptability of food. Moreover, 3D printing technology can achieve precise nutrition customization for some special groups, meeting the nutritional needs of people in different physiological stages and different health conditions, such as people who are losing weight, the elderly, children, and people with swallowing disorders. However, the current limitation on the application of 3D printing technology in food is that the food materials that can be 3D printed are limited and urgently need to be expanded. With the continuous development of 3D printing technology, it is increasingly combined with the modern food industry, which can achieve high efficiency, personalization, and sustainability of food production, while meeting the nutritional needs of a diverse population.

[0003] The amino acid composition of oat protein is relatively balanced, and the content of various essential amino acids is close to or slightly higher than the recommended value of the World Health Organization, but the protein powder tastes unacceptable and is difficult to swallow, making it unsuitable for direct consumption. Applying it to 3D printing can produce personalized customized foods with balanced nutrition and unique taste, achieve precise nutrition, and help people with special needs get enough protein intake.

[0004] Oat protein gel is not suitable for 3D printing due to its high strength and high brittleness. Proteins and polysaccharides will spontaneously interact to form weak gels due to intermolecular interactions such as hydrogen bonds, hydrophobic interactions, and van der Waals forces without external treatment, but the binding force is weak. External treatments such as heating can cause the polysaccharide to undergo a Maillard reaction with the protein to generate a more stable covalent bond, thereby enhancing the strength of the gel and making the gel more stable. By controlling the ratio of protein to polysaccharide, the physical properties of the gel such as hardness and viscosity can be adjusted to meet the characteristics of 3D printing.

[0005] Curcumin is a plant polyphenol that has been shown to have good effects in anti-oxidation, anti-bacterial, anti-tumor, immunomodulatory, and anti-radiation. Curcumin has broad application prospects in the food field, but it still has obstacles such as poor water solubility, chemical instability, sensitivity to light and heat, and low bioavailability. Studying the interaction between curcumin and oat protein is of great significance for improving the properties of curcumin and increasing its bioavailability. Hydrogel is a polymer with a cross-linked network structure, which has good hydrophilicity, biocompatibility and degradability. In recent years, in the field of food science, hydrogels have been used to develop delivery systems to encapsulate, protect and release bioactive molecules, and have played an important role in flavor substances, functional ingredients and drug delivery.

[0006] Hu Qiuhui et al. (publication number: CN 114409924A) disclosed a Flammulina velutipes polysaccharide-soy protein gel suitable for 3D printing and a preparation method thereof. The method mixes a soybean protein solution and a Flammulina velutipes polysaccharide solution to prepare a gel for application in 3D printing. However, the method does not load any nutrients. Summary of the invention:

[0007] The technical problem to be solved by the present invention is to prepare food-grade 3D printing materials suitable for people with swallowing disorders; the 3D printing materials can be loaded with hydrophobic bioactive substances to meet people's needs for specific nutrition.

[0008] (Technical solution) The present invention provides an extraction process of oat protein. The main steps of the process are: naked oats are used as raw materials, crushed and sieved, soaked in petroleum ether for 24 hours to obtain defatted oat flour, the obtained defatted oat flour is mixed with deionized water in a volume ratio of 1: (6-14), magnetically stirred for 30 minutes to obtain oat slurry, the obtained oat slurry is adjusted to pH 9-11, placed in a constant temperature water bath for leaching and stirring, centrifuged and the supernatant is taken, the pH value of the obtained supernatant is adjusted to 4-5, acid precipitation is performed for 1 hour and then centrifuged again, the precipitate is washed with water into a beaker after centrifugation, the pH is adjusted to neutral after sufficient magnetic stirring, and the sample is freeze-dried to obtain oat protein.

[0009] The present invention provides a method for preparing an oat protein gel system suitable for 3D printing loaded with curcumin, the obtained gel system can effectively improve the stability and bioaccessibility of curcumin, and can be applied to 3D printed food to solve the problem of dysphagia. The method comprises the following steps:

[0010] Step 1: Take naked oats as raw materials, grind and sieve them, soak them in petroleum ether for defatting for 24 hours to obtain defatted oatmeal powder, mix the obtained defatted oatmeal powder with deionized water in a volume ratio of 1: (6-14), and stir magnetically for 30 minutes to obtain oat slurry, adjust the pH of the obtained oat slurry to 9-11, place it in a constant temperature water bath for leaching and stirring, take the supernatant after centrifugation, adjust the pH value of the obtained supernatant to 4-5, centrifuge again after acid precipitation for 1 hour, wash the precipitate with water into a beaker after centrifugation, adjust the pH to neutral after sufficient magnetic stirring, and freeze-dry the sample to obtain oat protein.

[0011] Step 2: using oat protein and carrageenan as raw materials, dissolving oat protein in water to prepare an oat protein solution, adding curcumin solution dropwise to the protein solution until mixed evenly, dissolving carrageenan in water to prepare a carrageenan solution, mixing the oat protein-curcumin mixed solution with the carrageenan solution and cooling to room temperature to obtain an oat protein gel system loaded with curcumin.

[0012] The ratio of defatted oatmeal powder to deionized water in the oatmeal slurry described in step 1 is 1:6-14, alkali is added to adjust the pH to 9-11 during alkali dissolution, acid is added to adjust the pH to 4-5 during acid precipitation, and the extraction temperature is 30-50°C.

[0013] In the step 2, a 1-9% (w / v) oat protein solution is prepared, and after stirring and dissolving, 60 mg of curcumin is dissolved in 3 ml of 75% ethanol until it is completely dissolved, and then the curcumin solution is added dropwise to the oat protein solution and stirred for 1 hour until it is fully stirred; and a 1-5% (w / v) carrageenan solution is prepared and placed under magnetic stirring to fully mix it, and the oat protein solution loaded with curcumin is added dropwise to the carrageenan solution and stirred in a constant temperature water bath for 1 hour. The resulting paste mixture is cooled at room temperature for 15 minutes, and the sample is stored in a refrigerator overnight to obtain an oat protein gel system loaded with curcumin.

[0014] The oat protein, curcumin solution and carrageenan solution in step 2 are mixed by stirring; the stirring speed is 600-1000 rpm, and the stirring time is 30-60 min.

[0015] Another object of the present invention is to provide the oat protein gel system suitable for 3D printing as a water-holding substrate or a 3D printing substrate or as a carrier for embedding functional substances.

[0016] When the oat protein gel system is used as a carrier to load functional substances, oat protein is used to wrap curcumin to prepare a gel system, and after being eaten, the nutrients are released to a specific position.

[0017] Another object of the present invention is to provide the use of the oat protein gel system suitable for 3D printing in the preparation of food for people with dysphagia.

[0018] When the oat protein gel system of the present invention is used to prepare 3D printed food, the steps include establishing a 3D printing model, setting parameters such as nozzle diameter and nozzle moving speed for 3D printing. The nozzle diameter can be selected to be 0.8 to 1.2 mm, and the nozzle moving speed can be 10 to 30 mm / s.

[0019] The present invention uses naked oats as raw materials, and the oat protein gel system loaded with curcumin prepared without adding any inorganic materials has high biological safety. In addition, oats are one of the crops cultivated in large quantities worldwide, and were identified as functional foods of medicinal and edible origin by FDA (U.S. Food and Drug Administration) in 1997, and their nutritional value is very high. Oat protein is a high-quality cereal protein, and the protein content is at a higher position in cereals, the extracted protein extraction rate is higher, and the water solubility is good.

[0020] Beneficial effects:

[0021] ① The present invention selects biomacromolecule oat protein as the product raw material. Oat protein is a green and healthy plant protein, rich in fiber and multiple vitamins, with low fat and cholesterol content, and helps prevent health problems such as cardiovascular diseases.

[0022] ② Utilize the intermolecular bonding of oat protein and carrageenan to improve their 3D printing properties and prepare food that is easy for people with dysphagia to eat.

[0023] ③ The oat protein gel system of the present invention is suitable for making 3D printed products of various shapes, with high printing accuracy, achieving the purpose of high-protein food processing, customized food structure, and functional food nutrition. The printed product has a uniform texture, will not show obvious deformation within at least 30 minutes, has strong stability, and can maintain a good shape.

[0024] ④ The present invention does not require complicated processing procedures, has strong operability, and has a wide range of application scenarios.

[0025] ⑤ The present invention uses oat protein and carrageenan to prepare a gel system, which has strong stability, excellent rheological properties and thixotropic recovery, can be used as a 3D printing material, and can effectively protect bioactive substances. Specifically, the present invention uses oat protein to prepare a gel system, which still has self-supporting force after inversion, is very suitable for 3D printing, and has good prospects in the application of new nutrient delivery systems and food-grade 3D printing materials; the storage modulus is higher than the loss modulus, and has typical characteristics of gel. Description of the drawings:

[0026] Figure 1The figure is an appearance morphology diagram of a curcumin-loaded oat protein gel system prepared with a carrageenan concentration of 1 to 5%.

[0027] Figure 2 The present invention is a measurement result of the viscosity change of the curcumin-loaded oat protein gel system prepared with a carrageenan concentration of 1 to 5% as a function of shear rate.

[0028] Figure 3 The invention is the measurement result of the storage modulus and loss modulus of the curcumin-loaded oat protein gel system prepared with the carrageenan concentration of 1 to 5% as a function of frequency.

[0029] Figure 4 The curcumin release rate is obtained by an in vitro simulated digestion experiment of an oat protein gel system loaded with curcumin prepared with a carrageenan concentration of 1 to 5%.

[0030] Figure 5 These are the appearance pictures of the curcumin-loaded oat protein gel system prepared with a carrageenan concentration of 1 to 5% at 0, 1, and 3 hours after 3D printing. Specific implementation method:

[0031] In order to enable those skilled in the art to more clearly understand the technical features, purposes and beneficial effects of the present invention, the technical scheme of the present invention is now described in detail below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0032] Oat protein is extracted in the following manner: naked oats are used as raw materials, crushed and sieved, and then soaked in petroleum ether for defatting for 24 hours to obtain defatted oat flour, the defatted oat flour is mixed with deionized water in a volume ratio of 1: (6-14), and magnetically stirred for 30 minutes to obtain oat slurry, the pH of the oat slurry is adjusted to 9-11, placed in a constant temperature water bath for leaching and stirring, centrifuged and the supernatant is taken, the pH value of the supernatant is adjusted to 4-5, acid precipitation is performed for one hour and then centrifuged again, the precipitate is washed with water into a beaker after centrifugation, the pH is adjusted to neutral after sufficient magnetic stirring, and the sample is freeze-dried to obtain oat protein.

[0033] Example 1: Extraction of oat protein

[0034] (1) Preparation of defatted oatmeal powder: Using naked oats as raw materials, crushing the naked oats into oatmeal powder and sieving, and soaking and defatting in petroleum ether for 24 hours to obtain defatted oatmeal powder;

[0035] (2) Preparation of oat slurry: The defatted oatmeal powder obtained in step 1) was mixed with deionized water at a volume ratio of 1:10, and magnetically stirred for 30 minutes to obtain oat slurry;

[0036] (3) adding alkaline solution for alkaline dissolution: first, the pH of the oat slurry obtained in step 2) is adjusted to 9 using a pH meter, and after the pH is adjusted, the oat slurry is placed in a constant temperature water bath at 45° C. and stirred for 90 minutes, and the supernatant is collected by centrifugation;

[0037] (4) Adding dilute acid for acid precipitation: adjusting the pH to the isoelectric point of 4.5, centrifuging again after acid precipitation for 1 hour, washing the precipitate with water into a beaker after centrifugation, adjusting the pH to neutral after sufficient magnetic stirring, and freeze-drying the sample to obtain oat protein.

[0038] The oat protein extraction rate measured in this example is 68.43%.

[0039] Example 2: Preparation method of curcumin-loaded oat protein gel system

[0040] (1) After naked oats are crushed and sieved, they are soaked in petroleum ether for defatting for 24 hours to obtain defatted oat flour. 100 g of defatted oat flour is mixed with 3 L of deionized water and homogenized at 5000 rpm for 30 minutes. The pH of the obtained oat homogenate is adjusted to 10, placed in a 40°C constant temperature water bath for leaching and stirring for 1.5 hours, and centrifuged at 10000 rpm for 20 minutes to obtain the supernatant. The pH of the obtained supernatant is adjusted to 4.5, and after acid precipitation for one hour, it is centrifuged again. After centrifugation, the precipitate is washed with water into a beaker, and after sufficient magnetic stirring, the pH is adjusted to neutral. After freeze-drying, oat protein is obtained.

[0041] (2) Prepare a 5% oat protein solution, stir and dissolve it, dissolve 60 mg of curcumin in 3 ml of 75% ethanol solution, and add it dropwise into the oat protein solution and stir it magnetically for 1 hour until it is evenly mixed, and prepare a 3% carrageenan solution, mix the oat protein-curcumin mixed solution with the carrageenan solution and place it in a 60°C water bath and stir it for 1 hour to fully mix it, thereby obtaining a 3D food printing material.

[0042] (3) Pour the prepared 3D food printing material into a syringe in a flowing state, taking care not to form any bubbles, and refrigerate at 4°C for 12 hours for the experiment.

[0043] (4) 3D printing steps: The 3D printer used this time is a FOODBOT-S2Pro extrusion 3D printer with an independent heating unit. A 3D printing model was established for printing (printing model: cylinder, diameter 20mm, height 20mm, filling density 70%, bottom thickness 1mm, height 0.8mm), and the printing material was kept at the printing temperature for 30 minutes before printing began. The printing nozzle diameter, printing speed and printing temperature were 0.84mm, 25.0mm s -1 and 25℃.

[0044] (5) Product characterization:

[0045] (1) Performance: The 3D printed food materials processed according to this step can still maintain a certain mechanical strength and structural integrity after being placed for a period of time after printing, without collapse, which is related to the content of oat protein and carrageenan. The helical aggregation of the molecular conformation between oat protein and carrageenan increases the mechanical strength of the 3D printed food materials, the stability of the printed samples, and the smooth surface of the product.

[0046] (2) Printing: Due to the uniform filling of the printing material in the formula and the high water content, the extrusion process is smooth, the nozzle is not blocked during the extrusion process, and the printing process is continuous without broken strips.

[0047] Example 3: Preparation method of curcumin-loaded oat protein gel system

[0048] (1) After naked oats are crushed and sieved, they are soaked in petroleum ether for defatting for 24 hours to obtain defatted oat flour. 100 g of defatted oat flour is mixed with 3 L of deionized water and homogenized at 5000 rpm for 30 minutes. The pH of the obtained oat homogenate is adjusted to 10, placed in a 40°C constant temperature water bath for leaching and stirring for 1.5 hours, and centrifuged at 10000 rpm for 20 minutes to obtain the supernatant. The pH of the obtained supernatant is adjusted to 4.5, and after acid precipitation for one hour, it is centrifuged again. After centrifugation, the precipitate is washed with water into a beaker, and after sufficient magnetic stirring, the pH is adjusted to neutral. After freeze-drying, oat protein is obtained.

[0049] (2) Prepare a 5% oat protein solution, stir and dissolve it, dissolve 60 mg of curcumin in 3 ml of 75% ethanol solution, and add it dropwise into the oat protein solution and stir it magnetically for 1 hour until it is evenly mixed, and prepare a 4% carrageenan solution, mix the oat protein-curcumin mixed solution with the carrageenan solution and place it in a 60°C water bath and stir it for 1 hour to fully mix it, thereby obtaining a 3D food printing material.

[0050] (3) Pour the prepared 3D food printing material into a syringe in a flowing state, taking care not to form any bubbles, and refrigerate at 4°C for 12 hours for the experiment.

[0051] (4) 3D printing steps: The 3D printer used this time is a FOODBOT-S2Pro extrusion 3D printer with an independent heating unit. A 3D printing model was established for printing (printing model: cylinder, diameter 20mm, height 20mm, filling density 70%, bottom thickness 1mm, height 0.8mm), and the printing material was kept at the printing temperature for 30 minutes before printing began. The printing nozzle diameter, printing speed and printing temperature were 0.84mm, 25.0mm s -1 and 25℃.

[0052] 3D printing of oat protein gel prepared with different concentrations of carrageenan: the prepared material was tightly filled into the 3D printer barrel, and a print nozzle with a diameter of 0.84 mm was selected. A 3D model was made (the model was set as a cylinder with a diameter of 20 mm and a height of 20 mm), and the parameters were set and sliced ​​through the slicing software. The printing speed was 15 mm / s, the printing temperature was 25°C, the printing platform height was 1 mm, and the filling rate was 80%. The actual pictures of the printed products after 0, 1h, and 3h are shown in the figure. Figure 1 . From the actual pictures of the printed products, there is an obvious depression in the middle of the oat protein gel printed products when the carrageenan concentration is 1% and 3%, which is due to the collapse of the gel strength due to its low strength. In addition, the oat protein gel with carrageenan concentration of 4% and 5% has a high viscosity, and the friction between the gel and the nozzle during the extrusion process makes the printed product surface rough, and also causes foundation difficulties.

Claims

1. A process for extracting oat protein, characterized in that: The naked oats are crushed and sieved, and then soaked and defatted with an organic solvent to obtain defatted oatmeal powder, and oat protein is extracted by an alkali dissolution and acid precipitation method, and then freeze-dried to obtain oat protein, which specifically includes the following steps: 1) using naked oats as raw materials, crushing and sieving, and then soaking and defatting with an organic solvent to obtain defatted oatmeal powder; 2) mixing the obtained defatted oatmeal powder with deionized water according to a certain volume, and stirring with a magnetic force for 30 minutes to obtain oatmeal slurry; 3) adding an alkaline solution to the oat slurry obtained in step 2) to adjust the pH to alkaline for alkaline dissolution, placing the oat slurry in a constant temperature water bath for leaching and stirring, and collecting the supernatant after centrifugation; 4) Add dilute acid to the supernatant to adjust the pH value to 4.5 for acid precipitation. Centrifuge again after one hour of acid precipitation. Wash the precipitate into a beaker with water after centrifugation. Adjust the pH to neutral after sufficient magnetic stirring. Freeze-dry the sample to obtain oat protein.

2. A method for preparing oat protein gel capable of loading curcumin and suitable for 3D printing, characterized in that: The specific steps include: The method uses oat protein and carrageenan as raw materials, dissolves oat protein in water to prepare an oat protein solution, adds curcumin solution dropwise into the protein solution until the mixture is uniformly mixed, dissolves carrageenan in water to prepare a carrageenan solution, mixes the oat protein-curcumin mixed solution with the carrageenan solution, and cools the mixture to room temperature to obtain an oat protein gel system loaded with curcumin.

3. The method according to claim 2, characterized in that Step (1) In step 1, a 1-9% (w / v) oat protein solution is prepared, and after stirring and dissolving, 60 mg of curcumin is dissolved in 3 mL of 75% ethanol until it is completely dissolved. Subsequently, the curcumin solution is added dropwise to the oat protein solution and stirred for 1 hour until it is fully stirred and uniform; and a 1-5% (w / v) carrageenan solution is prepared and placed under magnetic stirring to fully mix it, and the oat protein solution loaded with curcumin is added dropwise to the carrageenan solution and fully stirred in a constant temperature water bath for 1 hour. The resulting paste mixture is cooled at room temperature for 15 minutes, and the sample is stored in a refrigerator overnight to obtain an oat protein gel system loaded with curcumin.

4. A method for 3D printing of an oat protein gel system loaded with curcumin, characterized in that: The specific steps include: The prepared oat protein gel system sample loaded with curcumin was used as the raw material for 3D printing. Before printing, the machine was equilibrated at 25°C to achieve temperature equilibrium. The printing parameters were: first layer height 1mm, filling rate 80%, nozzle diameter 0.84mm, nozzle moving speed 15mm / s, wire diameter 28mm, and printing temperature 25°C. The printed product was photographed at 0h, 1h, and 3h after printing.

5. The process for extracting oat protein according to claim 1, wherein: When degreasing by soaking in petroleum ether, the mass ratio of oatmeal powder to petroleum ether liquid is 1:3 and the leaching time is 24 hours.

6. The process for extracting oat protein according to claim 1, characterized in that In steps 2), 3) and 4), the material-liquid ratio of defatted oatmeal powder to deionized water is 1:10, the extraction pH is 10, the extraction time is 90 minutes, and the extraction temperature is 40°C.

7. Use of the oat protein gel system according to claim 2 in encapsulating, loading or delivering nutrients.

8. Use of the curcumin-loaded oat protein gel system according to claim 3 in 3D printed food.

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