High-performance natural biomaterial, preparation method and application thereof

Abstract

The application relates to a high-performance natural biomaterial, a preparation method and application thereof, and belongs to the technical field of functional composite materials. The application aims to utilize the condensed phase of corn protein to manufacture a polymer solution for film manufacturing at room temperature. Compared with a corn protein film prepared by a traditional solution casting method, the application only utilizes the condensed phase of the corn protein, so that the solvent of the excess phase can be recycled. Preliminary results show that, by shearing the condensed phase of the corn protein, the prepared corn protein film has more excellent mechanical properties, which provides a simple method for preparing a plant protein-based plastic film without a chemical crosslinking agent. The corn alcohol-soluble protein is of a plant source and can be applied in the fields of food, cosmetics, pharmacy and the like.

Description

Technical Field

[0001] This invention relates to a method for preparing composite materials, specifically to a high-performance natural biomaterial, its preparation method, and its applications, belonging to the field of functional composite materials. Background Technology

[0002] Over the past few decades, rising healthcare costs, the public's aspiration for a high-quality life, and increased life expectancy have led to increasingly higher demands for food. People have become more aware of the safety and practicality of food packaging films. PE, a common coating material for fruits and vegetables, causes some environmental pollution and resource waste, and contains certain additives, which can have negative effects on human health with long-term consumption.

[0003] Proteins, due to their renewable nature and abundant availability in nature, have become a research hotspot among many natural biomass polymers. Currently, most proteins are industrial byproducts with low utilization rates, and for every kilogram of protein wasted, 15 to 750 kilograms of carbon dioxide are released into the atmosphere. Furthermore, protein waste not only contributes to climate change but also triggers a series of environmental problems. Utilizing proteins to prepare protein-based bioplastics to improve protein utilization is an effective way to address protein waste.

[0004] To promote the aggregation of protein molecules for material preparation, studies have shown that hydrophobic interactions, electrostatic interactions, disulfide bonds, and hydrogen bonds can facilitate protein aggregation. Therefore, proteins possess excellent film-forming abilities, enabling the formation of membrane materials with good water stability and light transmittance. However, they also face challenges such as low strength. Currently, membrane materials are mainly prepared from animal proteins, such as whey protein and casein. However, animal proteins have a high carbon footprint, and their high hydrophilicity results in high water vapor permeability in the prepared membrane materials, limiting their practical applications.

[0005] Compared to animal proteins, plant proteins have the potential to replace animal proteins in membrane preparation. They are inexpensive, widely available, have a lower carbon footprint, and are more hydrophobic, mitigating the problem of excessive hydrophilicity in animal protein membranes. They are therefore a greener and more sustainable biomaterial. Currently, the main problem in the preparation and production of corn protein-based films is the low mechanical strength of pure corn protein membranes, which is due to the weak molecular chain interactions during solution casting. Researchers often try to improve the mechanical strength of corn protein membranes by adding small molecule crosslinking agents, such as citric acid, glutaraldehyde, and other chemical crosslinking agents. However, this increases potential health risks and limits its application in the food and cosmetic fields. Summary of the Invention

[0006] To address the problem of poor mechanical properties in films prepared by common solution casting methods, this invention provides a high-performance natural biomaterial, its preparation method, and its applications without the addition of crosslinking agents.

[0007] The inventive concept of this invention:

[0008] First, corn protein originates from corn, which is abundant in nature but has low nutritional value and is often an industrial byproduct. Corn protein's unique solubility is unparalleled; as a hydrophobic protein, it is the only protein that can dissolve in an alcohol-water solution: corn protein dissolves in an ethanol-water solution but not in pure water. As the ethanol content decreases, corn gliadin transforms from a dissolved, random chain state into a condensed phase. A condensed phase refers to the phenomenon where some plant proteins undergo liquid-liquid phase separation under specific conditions, and is divided into a dense protein phase (often called a condensed phase) and a dilute protein phase (often called an excess phase).

[0009] Currently, no methods have been reported to improve the mechanical strength of pure corn gluten membranes without the addition of crosslinking agents, although this is theoretically feasible. This invention aims to utilize the cohesive properties of corn gluten to manufacture polymer melts for thin film production at room temperature. Compared to corn gluten membranes prepared by conventional solution casting, this invention utilizes only the condensed phase of corn gluten, thus allowing for the recycling of the excess solvent. Furthermore, compared to the weak interactions between molecular chains in solution, the molecular chains in the condensed phase of corn gluten are closer together, resulting in stronger intermolecular forces, which is beneficial for improving the mechanical properties of corn gluten membranes. Preliminary results indicate that improving the mechanical properties of membrane materials without the addition of additives is feasible.

[0010] This invention reduces the ethanol content of a zein-based aqueous solution by adding deionized water, thereby obtaining a zein-based condensate phase (a high-performance natural biomaterial). This zein-based condensate phase can be coated into a high-performance food contact film using a coating method. Furthermore, this food contact film exhibits low food migration, effectively meeting national and European standards.

[0011] To achieve the above objectives, the technical solution of the present invention is as follows:

[0012] A method for preparing a high-performance natural biomaterial, wherein the natural biomaterial is formed from zein aggregates obtained by adding deionized water to an aqueous alcohol solution to reduce the ethanol content. Specifically, the method includes the following steps:

[0013] (1) Dissolve zein in an alcohol-water solution;

[0014] (2) Add deionized water to the alcohol-water solution containing zein to reduce the ethanol content and obtain a dispersion of zein condensate.

[0015] (3) The dispersion of the zein condensate phase prepared in step (2) is centrifuged or allowed to settle naturally, and the lower precipitate is removed to obtain high-performance natural biomaterials.

[0016] Furthermore, in step (1), the ethanol content in the alcohol-water solution is 60-90 (v / v)%, the concentration of zein in the alcohol-water solution is 10-100 mg / mL, and the pH is 4-10.

[0017] Furthermore, in step (2), the ethanol content is reduced to 45-50% (v / v).

[0018] Furthermore, during centrifugation in step (3), the centrifugation speed is 4000-15000 r / min, the centrifugation time is 3-15 min, and the natural settling time is 8-12 h.

[0019] The application of the high-performance natural biomaterial obtained by the above preparation method is to use the high-performance natural biomaterial to prepare high-performance zein thin film material: the obtained zein condensate phase is used to prepare zein high-performance thin film material by a blade coating method.

[0020] Furthermore, the preparation methods specifically include the following:

[0021] The obtained zein condensate phase was scraped in the same direction at a speed of 0.5-10 cm / s using a film scraper, and then dried in an oven at 20-60℃ for 30-120 min to obtain a high-performance zein film material.

[0022] Furthermore, the high-performance thin film material has an elastic modulus ≥2000MPa, a tensile strength ≥30MPa, and an elongation at break ≥2%.

[0023] Furthermore, the aforementioned high-performance corn gliadin film material is applied in the fields of food and cosmetic contact films.

[0024] The beneficial effects of this invention are as follows: Currently, the condensed phase of corn protein is only used for microcapsule preparation; no one has utilized it for film material preparation. In fact, among all proteins, this invention is the first to utilize the condensed phase of protein to prepare film materials. Furthermore, the mechanical properties of the films prepared using condensed phase formation are improved several times, far exceeding those of all previously reported protein films, with strength even approaching that of common biodegradable plastic PLA. Common corn protein films are typically produced using solution casting, while this method uses condensed phase formation. This not only significantly improves mechanical strength without adding any additives, but also allows for the repeated use of the excess solvent, making it more green, economical, and sustainable. Finally, the condensed phase, as a polymer fluid, is more conducive to industrialization and large-scale production compared to solution casting. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments.

[0026] Comparative Example 1

[0027] (1) Preparation of zein solution: Dissolve 5g of zein in 500mL of 60(v / v)% alcohol-water solution.

[0028] (2) Preparation of the film: Pour the corn protein solution obtained in the step into a plastic petri dish and dry it at 40°C for 12 hours to obtain corn protein film 1.

[0029] Example 1

[0030] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 60 (v / v) and adjust the pH to 5.

[0031] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 47 (v / v)%, and allow it to settle naturally for 12 hours to obtain high-performance natural biomaterial 1.

[0032] (3) Preparation of film: The high-performance natural biomaterial 1 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the method of scraping film. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 1.

[0033] Example 2

[0034] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 60 (v / v) and adjust the pH to 7.

[0035] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 47 (v / v)%, and allow it to settle naturally for 12 hours to obtain high-performance natural biomaterial 2.

[0036] (3) Preparation of the film: The high-performance natural biomaterial 2 obtained in step (2) is prepared on a PET film with a thickness of 250 μm and a speed of 4 cm / s by a coating method. The coated film is placed in an oven at 40℃ and dried for 30 min to obtain the high-performance protein film 2.

[0037] Example 3

[0038] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 60 (v / v) and adjust the pH to 5.

[0039] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 47 (v / v)%, and allow it to settle naturally for 12 hours to obtain high-performance natural biomaterial 3.

[0040] (3) Preparation of film: The natural biomaterial 3 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 6 cm / s by the film scraping method. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 3.

[0041] Example 4

[0042] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 60 (v / v) and adjust the pH to 7.

[0043] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 47 (v / v)%, and allow it to settle naturally for 12 hours to obtain high-performance natural biomaterial 4.

[0044] (3) Preparation of film: The high-performance natural biomaterial 4 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the film scraping method. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 4.

[0045] Example 5

[0046] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 60 (v / v) and adjust the pH to 9.

[0047] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 47 (v / v)%, and allow it to settle naturally for 12 hours to obtain high-performance natural biomaterial 5.

[0048] (3) Preparation of film: The high-performance natural biomaterial 5 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the method of scraping film. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 5.

[0049] Example 6

[0050] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 60 (v / v) and adjust the pH to 7.

[0051] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 47 (v / v)%, centrifuge (12000 rpm, 10 min) to obtain high-performance natural biomaterial 6.

[0052] (3) Preparation of film: The high-performance natural biomaterial 6 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the film scraping method. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 6.

[0053] Example 7

[0054] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 65 (v / v) and adjust the pH to 7.

[0055] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 47 (v / v)%, centrifuge (12000 rpm, 10 min) to obtain high-performance natural biomaterial 7.

[0056] (3) Preparation of film: The high-performance natural biomaterial 7 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the method of scraping film. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 7.

[0057] Example 8

[0058] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 60 (v / v) and adjust the pH to 7.

[0059] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 45 (v / v)%, centrifuge (12000 rpm, 10 min) to obtain high-performance natural biomaterial 8.

[0060] (3) Preparation of film: The high-performance natural biomaterial 8 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the film scraping method. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 8.

[0061] Example 9

[0062] (1) Preparation of zein solution: Dissolve 15g of zein in 500mL of ethanol solution with a content of 60 (v / v) and adjust the pH to 7.

[0063] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 45 (v / v)%, and let it settle for 8 hours to obtain high-performance natural biomaterial 9.

[0064] (3) Preparation of film: The high-performance natural biomaterial 9 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the method of scraping film. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 9.

[0065] Example 10

[0066] (1) Preparation of zein solution: Dissolve 15g of zein in 1000mL of ethanol solution with a content of 90 (v / v) and adjust the pH to 7.

[0067] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 45 (v / v)%, and let it settle for 8 hours to obtain high-performance natural biomaterial 10.

[0068] (3) Preparation of film: The high-performance natural biomaterial 10 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the film scraping method. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 10.

[0069] Example 11

[0070] (1) Preparation of zein solution: Dissolve 20g of zein in 2000mL of ethanol solution with a content of 80 (v / v) and adjust the pH to 7.

[0071] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 45 (v / v)%, and let it settle for 8 hours to obtain high-performance natural biomaterial 11.

[0072] (3) Preparation of film: The high-performance natural biomaterial 11 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the film scraping method. The scraped film is placed in an oven at 40℃ and dried for 30 min to obtain high-performance protein film 11.

[0073] Example 12

[0074] (1) Preparation of zein solution: Dissolve 20g of zein in 200mL of ethanol solution with a content of 80 (v / v) and adjust the pH to 7.

[0075] (2) Obtaining the zein condensate phase: Add deionized water to the solution prepared in step (1) to adjust the ethanol content to 45 (v / v)%, and let it settle for 8 hours to obtain high-performance natural biomaterial 11.

[0076] (3) Preparation of film: The high-performance natural biomaterial 11 obtained in step (2) is prepared on PET film with a thickness of 250 μm and a speed of 2 cm / s by the film scraping method. The scraped film is placed in an oven at 40℃ and dried for 120 min to obtain high-performance protein film 12.

[0077] Mechanical performance testing

[0078] Table 1

[0079] Elastic modulus (MPa) Tensile strength (MPa) Fracture strain (%) Example 1 2205 42 3.2 Example 2 2778 52 2.9 Example 3 2793 53 2.7 Example 4 2953 54 3.1 Example 5 3252 55 4.3 Example 6 2852 55 4.3 Example 7 2741 50 2.6 Example 8 2765 52 2.7 Example 9 2832 51 2.8 Example 10 2804 49 3.1 Example 11 2797 54 3.4 Example 12 2837 53 2.8 Comparative Example 1 1191 9 1.5

[0080] Compared to the comparative example, the elastic modulus of the zein film prepared in this example is 2-3 times that of the comparative example, and its strength is 3-4 times that of the comparative example. This demonstrates that the film prepared from the natural biomaterials of this invention can have its mechanical strength greatly improved without adding any raw materials. Furthermore, testing showed that the migration rate of the prepared zein film to food was 2.7 ± 0.2 mg / dm³. 2 It meets EU standards (10 mg / dm³). 2 ).

[0081] In summary, the natural biomaterials described in this invention have significant advantages over corn protein films prepared by traditional methods, and have promising application prospects in fields such as food packaging.

Claims

1. A method for preparing a high-performance natural biomaterial, characterized in that, The preparation method includes the following steps: (1) Dissolve zein in an alcohol-water solution; (2) Add deionized water to the alcohol-water solution containing zein to reduce the ethanol content and obtain a dispersion of zein condensate. (3) The dispersion of the zein condensate phase prepared in step (2) is centrifuged or allowed to settle naturally, and the lower precipitate is removed to obtain high-performance natural biomaterials. In step (1), the ethanol content in the aqueous solution is 60-90% (v / v); in step (2), the ethanol content is reduced to 45-50% (v / v).

2. The method for preparing a high-performance natural biomaterial according to claim 1, characterized in that, In step (1), the concentration of zein in the alcohol-water solution is 10-100 mg / mL, and the pH is 4-10.

3. The method for preparing a high-performance natural biomaterial according to claim 1, characterized in that, In step (3), the centrifugation speed is 4000-15000 r / min and the centrifugation time is 3-15 min.

4. The method for preparing a high-performance natural biomaterial according to claim 1, characterized in that, The natural settling time is 8-12 hours.

5. A high-performance natural biomaterial obtained by the preparation method according to any one of claims 1-4.

6. The application of a high-performance natural biomaterial obtained by the preparation method according to any one of claims 1-4, characterized in that, High-performance natural biomaterials are used to prepare high-performance thin film materials of zein: The obtained zein condensate phase is used to prepare high-performance thin film materials of zein by a blade coating method.

7. The application according to claim 6, characterized in that, The high-performance thin film material has an elastic modulus ≥2000MPa, tensile strength ≥30MPa, and elongation at break ≥2%.

8. The application according to claim 6, characterized in that, Specifically, the preparation methods include the following: The obtained zein condensate phase was scraped in the same direction at a speed of 0.5-10 cm / s using a film scraper, and then dried in an oven at 20-60℃ for 30-120 min to obtain a high-performance zein film material.

9. The application according to claim 6, characterized in that, The aforementioned high-performance zein film material is applied in the fields of food and cosmetic contact films.