Method for preparing oil gel by using protein hydrolysate-cellulose aerogel template

Abstract

The invention discloses a method for preparing oil gel by using a protein hydrolysate-cellulose aerogel template, and belongs to the field of biological materials and foods. The method comprises the following steps: (1) preparing cereal protein hydrolysate; (2) preparing a protein hydrolysate-cellulose compound; (3) preparing a protein hydrolysate-cellulose aerogel; (4) carrying out post-treatment on the protein hydrolysate-cellulose aerogel; and (5) preparing the oil gel. According to the method, a protein hydrolysate-cellulose-based composite aerogel is prepared by adopting a dual enhancement strategy of combining electrostatic adsorption and chemical crosslinking, and the oleogel is prepared by taking the composite aerogel as a template through a simple physical oil absorption process. The oleogel is safe, non-toxic and edible, and no toxic reagent is added in the processing process. The oleogel shows a good strain memory effect and remarkable structural elasticity. And excellent oil absorption capacity, oil holding capacity and thermal stability are also shown. The simple method capable of enhancing the mechanical properties of the oleogel is suitable for commercial mass preparation, and the prepared oleogel can be used for replacing fat in artificial meat products.

Description

[0001] The invention belongs to the field of biomaterials and food, and mainly relates to a method for preparing oil gel by utilizing protein hydrolysate-cellulose aerogel template. Background Art

[0002] Solid fats have a significant impact on various qualities of food, including texture, storage time and taste. However, recent studies have shown that solid fats contain high levels of saturated fatty acids and trans fatty acids, and excessive consumption increases the risk of metabolic syndrome and cardiovascular disease. In addition, most solid fats come from animals, which is not conducive to carbon neutrality and sustainable development. To avoid these problems, oleogels have become a viable alternative to solid fats. Without changing the chemical properties of the oil, oleogels structure liquid oils into solid colloids to achieve the effect of simulating fat. After years of research, the preparation of oleogels can be divided into two methods: direct and indirect. The direct method is to add oleogels directly to the oil to form a crystalline particle network or a self-assembled system. Commonly used oleogels include monoglycerides, phytosterols, 12-hydroxystearic acid and certain waxes. However, the use of most oleogels in the food industry is limited due to the lack of food-grade gels, unstable structures under shear conditions, and unpleasant waxy taste. To overcome these challenges, researchers have turned their attention to indirect methods. In the indirect method, aerogels are considered to be potential templates for making oleogels.

[0003] Aerogels have highly porous structures, complex three-dimensional networks, and large specific surface areas. Therefore, oleogels prepared using aerogel templates have high oil absorption and excellent oil holding capacity. By simply immersing the aerogel in oil, it can be converted into oleogels through the action of surface tension and capillary forces. Compared with premixed oleogels, aerogels have lower production and transportation costs. In addition, the aerogel template method only involves physical oil absorption process, which is more suitable for loading heat-sensitive substances. Cellulose derivatives are widely used in the food industry because they are non-toxic, economical, and environmentally friendly. Due to the high aspect ratio and excellent toughness of cellulose chains, the aerogels prepared from them have significant flexibility and elasticity. Therefore, it is very suitable as a template for the preparation of oleogels. However, cellulose aerogels have lower mechanical properties than inorganic aerogels, which limits their application. At present, the most common solutions are biomineralization and chemical crosslinking. However, the poor compatibility between inorganic nanoparticles and cellulose and the presence of non-food components limit the application of biomineralization in the food industry. In terms of chemical crosslinking, cellulose contains abundant active hydroxyl groups, which can form covalent bonds through crosslinking. Commonly used cross-linking agents include carboxylic acids, hydrazines, and aldehydes. Among these cross-linking agents, citric acid is widely used in cellulose cross-linked foods because of its safety, non-toxicity, and edible properties. Plant-based proteins tend to interact with polysaccharides due to their rich active and charged groups, and form complexes with polysaccharides through electrostatic adsorption. Protein-based aerogels tend to be hard but brittle, while cellulose-based aerogels exhibit elasticity. Combining the two substances to prepare composite aerogels exhibits the advantages of both. In addition, studies have found that when fibers are combined with small particles with a higher specific surface area, stronger gels are formed, resulting in a tighter fiber network. In this case, protein hydrolysates have smaller particle sizes and increased surface group exposure, making them more suitable as building blocks than proteins.

[0004] The present invention proposes and adopts a dual reinforcement strategy combining electrostatic adsorption and chemical cross-linking for the first time to prepare protein hydrolyzate-cellulose-based composite aerogel, and uses the composite aerogel as a template to prepare oil gel through a simple physical oil absorption process. Cellulose is used as the aerogel skeleton, and protein hydrolyzate is adsorbed on the polysaccharide chain through electrostatic interaction to form a core-shell structure. The cellulose is chemically cross-linked in combination with citric acid. This dual reinforcement method significantly improves the mechanical properties of the oil gel prepared by the composite aerogel template. The oil gel exhibits good strain memory effect and significant structural elasticity. It also exhibits good oil absorption capacity, oil holding capacity and thermal stability. The oil gel prepared by the present invention may be used for fat replacement and active substance delivery in artificial meat products. Summary of the invention

[0005] The invention provides a method for preparing an oleogel by using a protein hydrolysate-cellulose aerogel template. The method has a simple operation process and low cost, and realizes the preparation of a healthy and safe high-strength fat mimetic.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] A method for preparing an oleogel using a protein hydrolysate-cellulose aerogel template, characterized in that the method comprises the following steps:

[0008] (1) Preparation of plant protein hydrolysate: Plant protein was obtained by isoelectric precipitation. Commercially available grains were ground, defatted, the solid-liquid ratio was adjusted, the pH was adjusted to 4.5, centrifuged, the pH was adjusted to 7.0 again, dialyzed, and then freeze-dried. The protein was then dissolved in deionized water and then hydrolyzed with papain (800,000 U / g) at 55°C and pH 7.0. The enzyme-to-substrate mass ratio was 1:400, and the solution was incubated with continuous stirring for 2 h. After protein hydrolysis, the solution was heated at 95°C for 10 min to inactivate the enzyme.

[0009] (2) Preparation of protein hydrolysate-cellulose complex: Dissolve cellulose in water to prepare a cellulose solution with a cellulose concentration of 0.1-5% (w / v), then add 0.1-10 times (w / w) the mass of cellulose of protein hydrolysate to the solution and mix well. Then add 1-40% (w / w) of the mass of cellulose of carboxylic acid. Heat the mixed solution at 30-95°C for 1-120 min.

[0010] (3) Preparation of protein hydrolysate-cellulose aerogel: The protein hydrolysate-cellulose composite solution is frozen at -20 to -80°C. The frozen solid is freeze-dried at -100 to -50°C.

[0011] (4) Post-treatment of protein hydrolysate-cellulose aerogel: The freeze-dried aerogel was placed in an oven and heat treated at 120-200 °C for 1-30 min, and then cooled at room temperature.

[0012] (5) Preparation of oil gel: Immerse the protein hydrolysate-cellulose aerogel in vegetable oil for 0-6 h, and obtain the oil gel after sufficient oil absorption.

[0013] The protein in step (1) includes but is not limited to one or more of soy protein, pea protein, chickpea protein, mung bean protein, wheat protein, potato protein, rice protein, peanut protein, yeast protein, almond protein, quinoa protein, etc.

[0014] The cellulose in step (2) includes but is not limited to cellulose derivatives such as carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, hydroxyethyl cellulose, etc. The carboxylic acid includes but is not limited to citric acid, sodium trimetaphosphate, etc.

[0015] The conditions for preparing the protein hydrolysate-cellulose composite in step (2) are as follows: the cellulose concentration is 1.5% (w / v), the amount of protein hydrolysate added is 100% of the mass of cellulose, and the amount of citric acid added is 10% of the mass of cellulose (w / w). The mixed solution is heated at 80°C for 20 min.

[0016] The preparation process of the protein hydrolysate-cellulose aerogel in step (3) is freezing at -20°C, and freeze-drying the frozen solid at -60°C.

[0017] The process conditions for post-treatment of the protein hydrolysate-cellulose aerogel in step (4) are to place the freeze-dried aerogel in an oven and heat treat it at 155° C. for 5 min.

[0018] In the step (5), the protein hydrolyzate-cellulose aerogel is immersed in vegetable oil for 1 hour, and the vegetable oil includes but is not limited to soybean oil, sunflower oil, olive oil, peanut oil, rapeseed oil, etc.

[0019] The present invention proposes and adopts for the first time a dual reinforcement strategy combining electrostatic adsorption and chemical cross-linking to prepare protein hydrolysate-cellulose-based composite aerogel, and uses the composite aerogel as a template to prepare oil gel through a simple physical oil absorption process. The oil gel is safe, non-toxic and edible, and no toxic reagents are added during the processing. The oil gel exhibits good strain memory effect and significant structural elasticity. It also exhibits good oil absorption capacity, oil holding capacity and thermal stability. Mechanical tests show that the maximum compressive strength of the oil gel reaches 0.343 MPa and the Young's modulus reaches 0.604 MPa. It can absorb up to 53.8 times its own weight of vegetable oil and up to 77.8% oil holding rate. This simple method for enhancing the mechanical properties of oil gel is suitable for commercial mass preparation, and the prepared oil gel can be used to replace fat in artificial meat products. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the overall process route diagram of the present invention. DETAILED DESCRIPTION

[0021] The present invention is described in detail below with reference to the accompanying drawings.

[0022] A method for preparing an oleogel using a protein hydrolysate-cellulose aerogel template, characterized in that the method comprises the following steps:

[0023] (1) Preparation of plant protein hydrolysate: Plant protein was obtained by isoelectric precipitation. Commercially available grains were ground, defatted, the solid-liquid ratio was adjusted, the pH was adjusted to 4.5, centrifuged, the pH was adjusted to 7.0 again, dialyzed, and then freeze-dried. The protein was then dissolved in deionized water and then hydrolyzed with papain (800,000 U / g) at 55°C and pH 7.0. The enzyme-to-substrate mass ratio was 1:400, and the solution was incubated with continuous stirring for 2 h. After protein hydrolysis, the solution was heated at 95°C for 10 min to inactivate the enzyme.

[0024] (2) Preparation of protein hydrolysate-cellulose complex: Dissolve cellulose in water to prepare a cellulose solution with a cellulose concentration of 0.1-5% (w / v), then add 0.1-10 times (w / w) the mass of cellulose of protein hydrolysate to the solution and mix well. Then add 1-40% (w / w) of the mass of cellulose of carboxylic acid. Heat the mixed solution at 30-95°C for 1-120 min.

[0025] (3) Preparation of protein hydrolysate-cellulose aerogel: The protein hydrolysate-cellulose composite solution is frozen at -20 to -80°C. The frozen solid is freeze-dried at -100 to -50°C.

[0026] (4) Post-treatment of protein hydrolysate-cellulose aerogel: The freeze-dried aerogel was placed in an oven and heat treated at 120-200 °C for 1-30 min, and then cooled at room temperature.

[0027] (5) Preparation of oil gel: Immerse the protein hydrolysate-cellulose aerogel in vegetable oil for 0-6 h, and obtain the oil gel after sufficient oil absorption.

[0028] The protein in step (1) includes but is not limited to one or more of soy protein, pea protein, chickpea protein, mung bean protein, wheat protein, potato protein, rice protein, peanut protein, yeast protein, almond protein, quinoa protein, lactoglobulin, etc.

[0029] The cellulose in step (2) includes but is not limited to cellulose derivatives such as carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, hydroxyethyl cellulose, etc. The carboxylic acid includes but is not limited to citric acid, sodium trimetaphosphate, etc.

[0030] The conditions for preparing the protein hydrolysate-cellulose composite in step (2) are as follows: the cellulose concentration is 1.5% (w / v), the amount of protein hydrolysate added is 100% of the mass of cellulose, and the amount of citric acid added is 10% of the mass of cellulose (w / w). The mixed solution is heated at 80°C for 20 min.

[0031] The preparation process of the protein hydrolysate-cellulose aerogel in step (3) is freezing at -20°C, and freeze-drying the frozen solid at -60°C.

[0032] The process conditions for post-treatment of the protein hydrolysate-cellulose aerogel in step (4) are to place the freeze-dried aerogel in an oven and heat treat it at 155° C. for 5 min.

[0033] In the step (5), the protein hydrolyzate-cellulose aerogel is immersed in vegetable oil for 1 hour, and the vegetable oil includes but is not limited to soybean oil, sunflower oil, olive oil, peanut oil, rapeseed oil, etc.

Claims

1. A method for preparing an oleogel using a protein hydrolysate-cellulose aerogel template, characterized in that: The method comprises the following steps: (1) Preparation of plant protein hydrolysate: Plant protein was obtained by isoelectric precipitation. Commercially available grains were ground, defatted, the solid-liquid ratio was adjusted, the pH was adjusted to 4.5, centrifuged, the pH was adjusted to 7.0 again, dialyzed and freeze-dried. The protein was then dissolved in deionized water and then hydrolyzed with papain (800,000 U / g) at 55°C and pH 7.

0. The enzyme-to-substrate mass ratio was 1:400, and the solution was incubated with continuous stirring for 2 hours. After protein hydrolysis, the solution was heated at 95°C for 10 min to inactivate the enzyme; (2) Preparation of protein hydrolysate-cellulose complex: Dissolve cellulose in water to prepare a cellulose solution with a cellulose concentration of 0.1-5% (w / v), then add 0.1-10 times (w / w) the mass of cellulose of protein hydrolysate to the solution and mix well. Then add 1-40% (w / w) of the mass of cellulose of carboxylic acid. Heat the mixed solution at 30-95°C for 1-120 min. (3) Preparation of protein hydrolysate-cellulose aerogel: The protein hydrolysate-cellulose composite solution is frozen at -20 to -80°C. The frozen solid is freeze-dried at -100 to -50°C; (4) Post-treatment of protein hydrolysate-cellulose aerogel: The freeze-dried aerogel is placed in an oven and heat treated at 120-200 °C for 1-30 min, and then cooled at room temperature; (5) Preparation of oil gel: Immerse the protein hydrolysate-cellulose aerogel in vegetable oil for 0-6 h, and obtain the oil gel after sufficient oil absorption.

2. The method for preparing oleogel using protein hydrolysate-cellulose aerogel template according to claim 1, characterized in that: The protein includes but is not limited to one or more of soy protein, pea protein, chickpea protein, mung bean protein, wheat protein, potato protein, rice protein, peanut protein, yeast protein, almond protein, quinoa protein, etc.

3. The method for preparing oleogel using protein hydrolysate-cellulose aerogel template according to claim 1, characterized in that: The cellulose includes but is not limited to cellulose derivatives such as carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, hydroxyethyl cellulose, etc. The carboxylic acid includes but is not limited to citric acid, sodium trimetaphosphate, etc.

4. The method for preparing oleogel using protein hydrolysate-cellulose aerogel template according to claim 1, characterized in that: The conditions for preparing the protein hydrolysate-cellulose composite are as follows: the cellulose concentration is 1.5% (w / v), the amount of protein hydrolysate added is 100% of the mass of cellulose, and the amount of citric acid added is 10% of the mass of cellulose (w / w). The mixed solution is heated at 80°C for 20 min.

5. The method for preparing oleogel using protein hydrolysate-cellulose aerogel template according to claim 1, characterized in that: The preparation process of the protein hydrolysate-cellulose aerogel is as follows: freezing at -20°C, and freeze-drying the frozen solid at -60°C.

6. The method for preparing oleogel using protein hydrolysate-cellulose aerogel template according to claim 1, characterized in that: The post-treatment process conditions of the protein hydrolysate-cellulose aerogel are as follows: placing the freeze-dried aerogel in an oven and heat treating it at 155° C. for 5 min.

7. The method for preparing oleogel using protein hydrolysate-cellulose aerogel template according to claim 1, characterized in that: The protein hydrolysate-cellulose aerogel is immersed in vegetable oil for 1 h, and the vegetable oil includes but is not limited to soybean oil, sunflower oil, olive oil, peanut oil, rapeseed oil and the like.

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