A peptoid type deep eutectic solvent and a preparation method and application thereof

Abstract

This invention relates to a peptide-like deep eutectic solvent, comprising glycerol, proline, and arginine. The invention utilizes the synergistic effects of glycerol, proline, and arginine to construct a continuous, dense, and dynamically tunable multi-site hydrogen bond network. This hydrogen bond network achieves highly efficient antifreeze protection through both bulk and interfacial mechanisms: at the bulk level, it inhibits ice nucleus formation by disrupting the ordered arrangement of water molecules through competitive hydrogen bonding, and promotes a glass transition during cooling, forming a metastable amorphous matrix that spatially restricts the diffusion and rearrangement of water molecules; at the ice-water interface level, it forms a dynamic adsorption layer that effectively hinders ice crystal growth and recrystallization. This peptide-like deep eutectic solvent achieves highly efficient inhibition of the entire ice crystal formation process, solving the problems of single hydrogen bond networks and insufficient antifreeze regulation in existing deep eutectic solvents. It can be widely applied in antifreeze fields such as food freezing and preservation, and anti-frost and anti-icing coatings.

Description

Technical Field

[0001] This invention relates to the fields of deep eutectic solvents, cryogenic protection, and food freezing technology, and particularly to a peptide-like deep eutectic solvent, its preparation method, and its application. Background Technology

[0002] Low-temperature freezing technology has been widely used in food processing, biological sample preservation, and biomedicine because it can effectively slow down the process of metabolism and deterioration, and extend the shelf life of products or the preservation time of samples by lowering the system temperature. However, during freezing and cryopreservation, the phase transition behavior of water molecules in the system inevitably leads to phenomena such as ice nucleus formation, ice crystal growth, and ice recrystallization. For food, the growth and rearrangement of ice crystals can damage cell structure and tissue integrity, resulting in juice loss, poor taste, and loss of nutrients. For biological samples (such as cells, tissues, and biomolecules), the formation of ice crystals can cause cell membrane rupture and loss of biological activity, seriously affecting the subsequent use value of the sample.

[0003] Traditional cryoprotectants (such as glycerol, dimethyl sulfoxide, polyols, and some sugars) primarily rely on the "colour effect" to lower the freezing point of the solution or to slow down water molecule migration by increasing the viscosity of the system to achieve their antifreeze mechanism. While these substances can delay the freezing process to some extent, they have significant limitations: First, their antifreeze effect is not highly targeted, making it difficult to simultaneously inhibit the entire process of ice nucleation, ice crystal growth, and recrystallization. Second, some cryoprotectants (such as dimethyl sulfoxide) are toxic, making them unsuitable for applications with high safety requirements, such as food processing. Third, during long-term low-temperature storage, their ability to regulate ice crystal evolution gradually diminishes, making it difficult to avoid low-temperature damage.

[0004] In recent years, deep eutectic solvents (DES) have gradually become a research hotspot in the field of cryogenic protection due to their advantages such as simple preparation, good biocompatibility, and environmental friendliness. However, most of the reported antifreeze-related deep eutectic solvents mainly use single polyols or sugars as hydrogen bond donors, and the hydrogen bond network structure formed with hydrogen bond acceptors is relatively simple. They can only achieve preliminary antifreeze effects by increasing the viscosity of the system. Their ability to regulate water molecule movement and ice crystal interface behavior under low temperature conditions is limited, and it is still difficult to achieve efficient and systematic inhibition of ice crystal formation and recrystallization.

[0005] Therefore, it is necessary to further improve existing deep eutectic solvents to achieve comprehensive suppression of ice crystal nucleation, ice crystal growth, and recrystallization processes. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a peptide-like deep eutectic solvent, its preparation method, and its application.

[0007] The technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a peptide-like deep eutectic solvent, the raw material components of which include glycerol, proline and arginine.

[0008] Preferably, the molar ratio of glycerol, proline and arginine is 1~4:0.5~2:0.5~2.

[0009] Preferably, the molar ratio of glycerol, proline and arginine is 2:1:1.

[0010] Preferably, the raw material composition further includes water, and the mass of the water is 18-22% of the mass of the peptide-like deep eutectic solvent.

[0011] Secondly, the present invention provides a method for preparing the peptide-like deep eutectic solvent described in any of the above embodiments, comprising the following steps: mixing the raw material components, heating and stirring until a uniform, transparent, and turbid liquid is formed, stopping heating and stirring, and cooling to room temperature to obtain the solvent.

[0012] Preferably, the heating temperature is 50~90℃.

[0013] Preferably, the stirring rate is 200~500 rpm.

[0014] Thirdly, the present invention provides the application of the peptide-like deep eutectic solvent described in any of the above embodiments or the peptide-like deep eutectic solvent prepared by the preparation method described in any of the above embodiments in the preparation of cryopreservatives, low-temperature preservation solutions and / or anti-frost and anti-icing coatings.

[0015] The beneficial effects of this invention are: (1) The peptide-like deep eutectic solvent of the present invention constructs a continuous, dense, and dynamically tunable multi-site hydrogen bond network through the synergistic effect of glycerol (hydroxyl), proline (carboxyl / amino) and arginine (guanidinyl). This hydrogen bond network achieves efficient antifreeze through a dual mechanism of bulk and interface: at the bulk level, it inhibits ice nucleus formation by disrupting the ordered arrangement of water molecules through competitive hydrogen bonding, and promotes the glass transition of the system during cooling to form a metastable amorphous matrix, which spatially restricts the diffusion and rearrangement of water molecules; at the ice-water interface level, a dynamic adsorption layer can be formed to effectively hinder ice crystal growth and recrystallization. The peptide-like deep eutectic solvent of the present invention can achieve efficient inhibition of the entire process of ice crystal formation, and its antifreeze performance is significantly better than that of traditional cryoprotectants and ordinary deep eutectic solvents that rely on a single mechanism of action, solving the problems of single hydrogen bond network and insufficient antifreeze regulation ability of existing deep eutectic solvents.

[0016] (2) The preparation process of the peptide-like deep eutectic solvent of the present invention is simple and mild. It can be synthesized in one step by conventional heating and stirring method without the need for complex equipment or harsh conditions. Moreover, the raw materials are safe and readily available food-grade chemicals, which can be easily used to achieve large-scale stable production.

[0017] (3) The peptide-like deep eutectic solvent of the present invention has high antifreeze efficiency and can meet the antifreeze application needs of multiple fields: as a cryopreservative for food freezing, it can significantly reduce the mechanical damage of ice crystals to food cells and tissue structures, maintain quality, and is especially suitable for the freezing of surimi products. It can significantly inhibit the thawing loss and cooking loss of surimi during repeated freeze-thaw cycles, maintain the water-holding capacity and structural stability of surimi protein, thereby alleviating myofibrillar protein denaturation and quality deterioration; as a low-temperature preservation solution for the low-temperature preservation of biological samples, it can effectively maintain the integrity and biological activity of samples such as cells and tissues; as an anti-frost and anti-icing coating material for the surface of substrates, it can significantly delay the formation of frost and reduce the adhesion of ice. Attached Figure Description

[0018] Figure 1 Comparison of appearance and polarized light microscopy images of deep eutectic solvents at different molar ratios; Figure 2 The graph shows the relationship between the viscosity and ionic conductivity of the deep eutectic solvents prepared in Example 1 and Comparative Examples 1-2 as a function of temperature. Figure 3 Infrared and nuclear magnetic resonance spectra of the deep eutectic solvents prepared in Example 1 and Comparative Examples 1-2; Figure 4 The graphs show the ice recrystallization inhibition behavior and glass transition temperature of the deep eutectic solvents prepared in Example 1 and Comparative Examples 1-2. Figure 5 The molecular electrostatic potential distribution diagrams based on quantum chemical calculations for the deep eutectic solvents prepared in Example 1 and Comparative Examples 1-2 are shown. Figure 6 A schematic diagram illustrating the anti-frosting effect of coating deep eutectic solvent coatings of Examples 1 and 1-2 on glass surfaces; Figure 7 The graph shows the effect of different antifreeze treatments on the thawing loss rate, cooking loss rate, and water retention of surimi after 0, 7, and 14 freeze-thaw cycles; where A represents the thawing loss rate, B represents the cooking loss rate, and C represents the water retention. Detailed Implementation

[0019] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0020] One aspect of this invention is to provide a peptide-like deep eutectic solvent, the raw material components of which include glycerol, proline and arginine.

[0021] In designing this peptide-mimicking deep eutectic solvent, this invention meticulously screened the hydrophilic and hydrophobic alternating structural features of natural antifreeze peptides, selecting arginine (a hydrophilic amino acid) and proline (a hydrophobic amino acid) as functional units to synergistically construct the solvent with the basic hydrogen bond donor glycerol. Arginine's strongly hydrophilic guanidinium group provides abundant hydrogen bond acceptor / donor sites; proline contributes hydrogen bond sites through its carboxyl / amino groups, while its hydrophobic, rigid pyrrolidine ring stabilizes the spatial network structure; and glycerol's multi-hydroxyl structure forms the basis of a continuous hydrogen bond network. This invention, by synergistically introducing specific amino acids into the deep eutectic solvent system, not only complementarily strengthens the hydrogen bond network but also simulates the hydrophilic and hydrophobic distribution characteristics of antifreeze peptides, thereby precisely controlling the arrangement and migration behavior of water molecules at the molecular level to achieve highly efficient antifreeze performance.

[0022] In a preferred embodiment of the present invention, the molar ratio of glycerol, proline, and arginine is 1~4:0.5~2:0.5~2. The present invention selects glycerol, proline, and arginine within the above molar ratio range, which is beneficial for the formation of stable hydrogen bonds between the components and avoids phase separation or crystallization due to an excess of any one component.

[0023] In a preferred embodiment of the present invention, the molar ratio of glycerol, proline, and arginine is 2:1:1. The peptide-like deep eutectic solvent prepared at this molar ratio forms the densest, most stable, and most dynamic hydrogen bond network, resulting in optimal antifreeze properties and low-temperature stability: its glass transition temperature reaches -59.3°C, and it exhibits an inhibition rate close to 100% in ice recrystallization inhibition tests.

[0024] In a preferred embodiment of the present invention, the raw material composition further includes water, the mass of which is 18-22% of the mass of the peptide-like deep eutectic solvent. In the peptide-like deep eutectic solvent of the present invention, an appropriate amount of water is beneficial to forming a uniform, transparent, and stable deep eutectic liquid phase system. For example, the mass of water can be 18%, 19%, 20%, 21%, 22%, etc., of the peptide-like deep eutectic solvent.

[0025] Another aspect of the present invention provides a method for preparing a peptide-like deep eutectic solvent according to any of the above embodiments, comprising the following steps: mixing the raw material components, heating and stirring until a homogeneous, transparent, and turbid liquid is formed, stopping heating and stirring, and cooling to room temperature to obtain the solvent. In the present invention, after the peptide-like deep eutectic solvent is prepared, it can be dried in a vacuum drying oven at 60°C for 12 hours, sealed, and stored in a light-proof and dry environment to avoid moisture absorption affecting its performance.

[0026] In a preferred embodiment of the present invention, the heating temperature is 50~90°C. For example, the heating temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, etc. The present invention does not impose a particular limitation on the heating time, until the system forms a homogeneous, transparent, and turbid liquid. At the above heating temperature, for example, the heating time can be 30~120 minutes.

[0027] In a preferred embodiment of the present invention, the stirring rate is 200-500 rpm. For example, the stirring rate can be 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, etc.

[0028] The preparation method of this invention is simple, mild, safe, and easily scalable. The method is carried out at normal pressure and medium to low temperatures, without the need for extreme conditions such as high pressure or high temperature; all raw materials used are food-grade or biological-grade, ensuring high safety; by clearly defining key process parameters such as heating and stirring, the high repeatability and batch stability of the preparation process are effectively guaranteed, which is beneficial for large-scale production.

[0029] In another aspect, the present invention provides the application of the peptide-like deep eutectic solvent of any of the above embodiments or the peptide-like deep eutectic solvent prepared by the preparation method of any of the above embodiments in the preparation of cryopreservatives, low-temperature preservation solutions and / or anti-frost and anti-icing coatings.

[0030] The peptide-like deep eutectic solvent of the present invention has high antifreeze efficiency and wide application scenarios, especially showing targeted advantages in the following three fields: (1) As a cryopreservative for food freezing: It can be directly added to food or used for food pre-freezing soaking treatment, significantly inhibiting ice crystal damage during freezing, and effectively maintaining the cell tissue structure and nutritional components of meat, fruits and vegetables, dairy products and other foods; taking fish paste as an example, the peptide-like deep eutectic solvent of the present invention is directly added at 2~8% of the mass of fish paste, which can inhibit the quality deterioration of fish paste during the freeze-thaw cycle, reduce the thawing loss and cooking loss of fish paste, and improve the water holding capacity of fish paste. (2) As a cryopreservation solution for the cryopreservation of biological samples: It is suitable for the cryopreservation of samples such as cells, tissues, biological macromolecules, protein drugs, and vaccines, and can effectively protect the cell membrane integrity and maintain the stability of bioactive components. (3) As an anti-frost and anti-icing coating for substrate surfaces: It can be applied to the surfaces of substrates such as metals, glass, and polymers by coating or impregnation. The resulting anti-frost and anti-icing coating can significantly delay the frost formation time, reduce ice adhesion, and has good abrasion resistance and stability. The peptide-like deep eutectic solvent of the present invention is constructed based on the synergistic hydrogen bonding of glycerol with proline and arginine. It has a stable amorphous structure and excellent antifreeze properties. The molar ratio of each component can be flexibly adjusted according to the antifreeze requirements of different application scenarios, and it has good application scalability.

[0031] In the following examples, proline is L-proline and arginine is L-arginine.

[0032] Example 1 The peptide-like deep eutectic solvent is composed of glycerol, proline, arginine, and water, wherein the molar ratio of glycerol, proline, and arginine is 2:1:1, and the mass of water is 20% of the mass of the peptide-like deep eutectic solvent. It is prepared by the following method, including the following steps: Weigh 2.0 mol (184 g) of glycerol, 1.0 mol (115 g) of proline, 1.0 mol (174 g) of arginine and water (118 g) and place them in a dry beaker. Heat and stir in a water bath at 70°C and 200 rpm until a homogeneous, transparent and turbid liquid is formed. Stop heating and stirring and allow the liquid to cool naturally to room temperature.

[0033] Comparative Example 1 The main difference between this comparative example and Example 1 is that the raw material components are different.

[0034] Weigh 3.0 mol (276 g) of glycerol, 1.5 mol (172 g) of proline and 112 g of water into a dry beaker at a molar ratio of glycerol:proline = 2:1. Heat and stir in a water bath at 70 °C and 200 rpm until a homogeneous, transparent, and turbid liquid is formed. Stop heating and stirring, and allow the liquid to cool naturally to room temperature to obtain a deep eutectic solvent.

[0035] Comparative Example 2 The main difference between this comparative example and Example 1 is that the raw material components are different.

[0036] Weigh 3.0 mol (276 g) of glycerol, 1.0 mol (174 g) of arginine, and 113 g of water into a dry beaker at a molar ratio of glycerol:arginine = 3:1. Heat and stir in a water bath at 70°C and 200 rpm until a homogeneous, transparent, and turbid liquid is formed. Stop heating and stirring, and allow the liquid to cool naturally to room temperature to obtain a deep eutectic solvent.

[0037] It should be noted that the molar ratios of the raw material components used in Example 1 (glycerol-proline-arginine GPR ternary system), Comparative Example 1 (glycerol-proline GP binary system), and Comparative Example 2 (glycerol-arginine GR binary system) are the preferred ratios of each system determined through preliminary experimental screening (see [link to relevant documentation]). Figure 1 A), therefore, these two binary systems with better performance are set as comparative examples.

[0038] The deep eutectic solvents prepared in Example 1 and Comparative Examples 1-2 were subjected to performance tests.

[0039] (1) Observation of appearance and analysis by polarizing microscope Each sample was visually observed and analyzed using a polarizing microscope (results are shown in...). Figure 1 ): Preferred molar ratio ( Figure 1 Examples 1 and 2 (B~1C) show that the three deep eutectic solvents are all transparent, homogeneous, high-viscosity liquids with no phase separation or precipitation and good macroscopic stability; POM observation shows that ( Figure 1 D), Samples of Examples 1 and 2 of Comparative Examples 1 and 2 all exhibited isotropic dark fields under orthogonally polarized light, with no obvious birefringence characteristics, confirming that they were completely amorphous structures and successfully formed deep eutectic phases.

[0040] (2) Viscosity and conductivity testing The deep eutectic solvents prepared in Example 1 and Comparative Examples 1-2 were tested: 2.1) Viscosity test: A Brookfield LVDV-II+P rotational rheometer was used with a constant shear rate of 10 s⁻¹. -1The test temperature was 20~60℃, and the apparent viscosity was recorded. The Arrhenius model was used for fitting, and the activation energy (Eη) of viscous flow was extracted. 2.2) Conductivity test: The ionic conductivity within the above temperature range was tested using a calibrated DDS-307A conductivity meter; the ion migration activation energy (Eσ) was extracted by fitting the Arrhenius model.

[0041] Viscosity and conductivity were tested on each sample (results are shown in...). Figure 2 In Examples 1 and 2, the apparent viscosity decreased exponentially with increasing temperature, conforming to the Arrhenius equation. Eη was 36.51 kJ·mol⁻¹ for the GP system. -1 GR system 47.64 kJ·mol -1 GPR system 50.59 kJ·mol -1 The GPR system exhibits the highest viscosity; its electrical conductivity increases significantly with increasing temperature, also conforming to the Arrhenius equation, with Eσ being 47.94 kJ·mol⁻¹ for the GP system. -1 GR system 34.35 kJ·mol -1 GPR system 39.09 kJ·mol -1 Viscosity and conductivity show a significant negative correlation.

[0042] (3) Fourier transform infrared spectroscopy and nuclear magnetic resonance testing The deep eutectic solvents prepared in Example 1 and Comparative Examples 1-2, as well as pure glycerol, were tested: 3.1) Fourier transform infrared spectroscopy test: A Bruker Tensor 27 spectrometer was used, with a test range of 4000~400cm. -1 4 cm resolution -1 The focus of the analysis is on the O–H / N–H expansion and contraction zone (3700~3000 cm). -1 ) and the C=O / C–N vibration region (1700~1500 cm) -1 ).

[0043] 3.2) Nuclear magnetic resonance (NMR) test: Using DMSO-d6 as solvent, the chemical shifts and peak shapes of hydroxyl and amine proton signals were analyzed using a Bruker Avance NEO 600 MHz NMR spectrometer.

[0044] Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy were performed on each sample (results are shown in [link]). Figure 3 Compared to the pure components, the characteristic peaks of the deep eutectic solvent systems in Examples 1 and Comparative Examples 1-2 showed a systematic red shift and broadening; the red shift amplitude of the O–H / N–H stretching region was 3181.01 cm⁻¹, which was greater than that of the GPR system. -1 >GR system (3189.20 cm)-1 )>GP system (3284.18 cm -1 The results confirmed that the GPR system exhibits the strongest and most complex hydrogen bonding, with each component synergistically constructing a multivalent hydrogen bond network. The proton signals in the three deep eutectic solvent systems showed low-field shifts and broadening. In the GPR system, the proton signals for hydroxyl and amine protons shifted to δ=5.12 ppm, higher than those in the GP system (δ=4.47 ppm) and the GR system (δ=4.63 ppm), confirming that the GPR system has stronger hydrogen bonding and forms a dynamically stable hydrogen bond network.

[0045] (4) Ice recrystallization inhibition performance and glass transition temperature test The deep eutectic solvents prepared in Example 1 and Comparative Examples 1-2, as well as pure glycerol, were tested: 4.1) Ice recrystallization inhibition test: A modified sucrose-assisted method was used to prepare a deep eutectic solvent at 1 mg / mL. -1 45 wt% sucrose-PBS solution was prepared; the solution was frozen at -20℃ for 5 min and then annealed at -6℃ for 30 min; ice crystal images were taken using a Nikon Eclipse microscope, and the ice crystal area was analyzed using ImageJ software. A blank sucrose-PBS solution was used as a control group.

[0046] 4.2) Glass transition temperature test: A Netzsch DSC 214 Polyma differential scanning calorimeter was used under a nitrogen atmosphere. 10 mg of sample was sealed in an aluminum crucible. The test temperature ranged from 25℃ to -80℃, with a heating / cooling rate of 10℃·min. -1 Record the glass transition temperature (Tg) and the exothermic peak of crystallization.

[0047] The ice recrystallization inhibition performance and glass transition temperature of each sample were tested (results are shown in...). Figure 4 After annealing for 50 min, the ice crystals in the control group grew and fused rapidly; the deep eutectic solvents of Examples 1 and 1-2 could inhibit ice crystal growth, with the GPR system showing the best effect, and the ice crystal area was <1000 μm. 2 The proportion reached 100.00%, significantly better than the GP system (78.11%) and GR system (87.04%). During the cooling process, none of the three deep eutectic solvents showed an exothermic peak during crystallization, maintaining an amorphous state; the Tg values ​​were -80.9℃ for glycerol, -74.7℃ for the GP system, -68.3℃ for the GR system, and -59.3℃ for the GPR system, with the GPR system exhibiting the highest Tg and the strongest low-temperature stability.

[0048] (5) Molecular simulation analysis of antifreeze mechanism Density functional theory (DFT) calculations were performed using Gaussian 09 software at the B3LYP / 6-311G(d,p) level to obtain the optimized molecular structure and molecular electrostatic potential (MEP) plot, and to analyze the interaction energy and hydrogen bond directionality.

[0049] Depend on Figure 5 It is known that there are strong intermolecular bonds between the components in Example 1 of the present invention, and the thermodynamics is stable. Among them, the glycerol hydroxyl group is a hydrogen bond acceptor, and the carboxyl, amino, and guanidine groups of amino acids are hydrogen bond donors, forming a dense electrostatic-hydrogen bond coupling network, which provides the molecular basis for the antifreeze performance.

[0050] (6) Preparation and performance testing of anti-frost coating Test: Equal amounts of Example 1, Comparative Examples 1-2, pure glycerin and water were applied to the glass surface to form a coating. The coated glass and blank glass were placed in a low temperature and high humidity environment (temperature -20℃, relative humidity 54%) and the frost formation was observed.

[0051] Depend on Figure 6 It can be seen that blank glass freezes within 10 minutes and frosts up noticeably within 30 minutes; while the glass with the coating of Example 1 on its surface freezes and frosts up to 60 minutes, with a thinner frost layer and slower growth.

[0052] (7) Application of cryoprotection in freeze-thaw cycle surimi The test results of the aforementioned model system have confirmed that the peptide-like deep eutectic solvent of the present invention has excellent ice crystal regulation performance, stable water migration characteristics and strong hydrogen bond network structure. This test further examines its application potential as a cryopreservative (i.e. antifreeze agent) in low-temperature preservation of real food systems (taking surimi as an example).

[0053] 7.1) Sample Preparation Fresh sea bass surimi was divided into a blank control group, treatment groups with different amounts of deep eutectic solvent (GP, GR, and GPR treatment groups), and a commercial antifreeze agent SUSO control group (containing 4% sucrose and 4% sorbitol by weight of surimi, using a standard commercial antifreeze formulation). The GP treatment group used the deep eutectic solvent prepared in Comparative Example 1, with 2%, 4%, and 8% of the surimi by weight, respectively; the GR treatment group used the deep eutectic solvent prepared in Comparative Example 2, with 2%, 4%, and 8% of the surimi by weight, respectively; and the GPR treatment group used the peptide-like deep eutectic solvent prepared in Example 1, with 2%, 4%, and 8% of the surimi by weight, respectively. After thorough mixing, all samples were dispensed into sealed bags and subjected to freeze-thaw cycles.

[0054] Freeze-thaw cycle conditions: The sample was frozen in a -20℃ freezer for 23 h, and then thawed in a 25℃ constant temperature water bath for 1 h. This is one complete freeze-thaw cycle. Seven and fourteen freeze-thaw cycles were performed respectively, with fresh fish paste as the reference.

[0055] 7.2) Test Indicators and Methods Thawing loss rate: Weigh the fish paste sample before freeze-thaw cycles (m0), and after freeze-thaw cycles, blot the free water on the sample surface with filter paper and weigh it (m1). The thawing loss rate is calculated using the following formula: Thawing loss rate (%) = (m0-m1) / m0 × 100%; Cooking loss rate: Weigh the thawed fish paste sample (m2), seal it, and heat it in an 85℃ water bath for 30 min. Remove it, cool it to room temperature, absorb the surface moisture, and weigh it (m3). The cooking loss rate is calculated using the following formula: Cooking loss rate (%) = (m2-m3) / m2×100%; Water-holding capacity (WHC): Determined by centrifugation. Weigh 5 g of fish paste sample and place it in a centrifuge tube of known mass. Centrifuge at 4℃ and 8000 r / min for 15 min. Discard the supernatant and weigh the sample after centrifugation. The water-holding capacity is calculated using the following formula: Water holding capacity (%) = mass of sample after centrifugation / mass of sample before centrifugation × 100%.

[0056] 7.3) Test Results and Analysis Figure 7 The effects of different antifreeze treatments on the thawing loss rate of fish paste after 7 and 14 freeze-thaw cycles were demonstrated. Figure 7 A) Cooking loss rate ( Figure 7 B) and water retention ( Figure 7 The effects of C) were observed. Results showed that repeated freeze-thaw cycles led to significant quality deterioration in the surimi from the control group, specifically a substantial increase in thawing and cooking losses, and a significant decrease in water-holding capacity. These changes were closely related to the destruction of the myofibrillar protein structure and protein denaturation caused by ice recrystallization: the formation and growth of ice crystals during freeze-thaw cycles caused mechanical damage to the myofibrillar protein network, disrupting the protein's natural conformation, leading to a decrease in the protein's water-binding capacity, ultimately resulting in juice loss and quality deterioration. All antifreeze treatments alleviated the quality deterioration of surimi caused by freeze-thaw cycles, and the effect was concentration-dependent. The 8% GPR treatment group exhibited the best cryoprotection effect: after 14 freeze-thaw cycles, the thawing loss rate of the surimi was only 0.35%, and the cooking loss rate was only 9.24%, both close to the levels of fresh surimi; simultaneously, the water-holding capacity of the surimi remained at 92.45%. These indicators were significantly better than other treatment groups and the control group, and also better than commercially available conventional antifreeze formulations.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A peptoid-based deep eutectic solvent, characterized in that, The raw material components include glycerol, proline, and arginine.

2. The peptoid-based deep eutectic solvent of claim 1, wherein, The molar ratio of glycerol, proline and arginine is 1~4:0.5~2:0.5~2.

3. The peptide-like deep eutectic solvent as described in claim 2, characterized in that, The molar ratio of glycerol, proline, and arginine is 2:1:

1.

4. The peptide-like deep eutectic solvent as described in claim 1, characterized in that, The raw material composition also includes water, and the mass of the water is 18-22% of the mass of the peptide-like deep eutectic solvent.

5. A method for preparing a peptide-like deep eutectic solvent as described in claim 1, characterized in that, The process includes the following steps: mixing the raw material components, heating and stirring until a homogeneous, transparent, and turbid liquid is formed, stopping heating and stirring, and cooling to room temperature to obtain the final product.

6. The method for preparing the peptide-like deep eutectic solvent as described in claim 5, characterized in that, The heating temperature is 50~90℃.

7. The method for preparing the peptide-like deep eutectic solvent as described in claim 5, characterized in that, The stirring speed is 200~500 rpm.

8. The use of a peptide-like deep eutectic solvent as described in any one of claims 1-4 or a peptide-like deep eutectic solvent prepared by the preparation method as described in any one of claims 5-7 in the preparation of cryopreservatives, low-temperature preservation solutions and / or anti-frost and anti-icing coatings.

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