Fish collagen peptides for improving skin moisture and elasticity and a method of preparing the same

Abstract

The application provides a fish collagen peptide for improving skin moisture and elasticity and a preparation method thereof. The method comprises the following steps: S1: soaking fish scales in water to soften the fish scales, to obtain softened fish scales; S2: soaking the softened fish scales in a pretreatment liquid containing a first polyol and a second polyol, so that the first polyol diffuses into the interlayer of the fish scale collagen, and the second polyol forms a hydration layer on the outer layer of the fish scale collagen, to obtain pretreated fish scales; S3: using an endoprotease to enzymatically hydrolyze the pretreated fish scales, so that fish collagen proteins in the fish scales are hydrolyzed into fish collagen peptides, to obtain an enzymatic hydrolysate; and S4: post-treating and drying the enzymatic hydrolysate to obtain the fish collagen peptide for improving skin moisture and elasticity. Through the above method, the mass proportion of low-molecular-weight polypeptides suitable for the application of improving skin moisture and elasticity in the obtained fish collagen peptide can be increased, and the stability of the molecular weight distribution of the product can be improved.

Description

Technical Field

[0001] This application relates to the field of collagen peptide technology, specifically to a fish collagen peptide for improving skin moisture and elasticity and its preparation method. Background Technology

[0002] Fish collagen peptides are a class of low-molecular-weight protein degradation products obtained through hydrolysis and other methods, using collagen from fish skin, fish scales, and other aquatic processing byproducts as raw materials. Due to their safe origin, low fat content, and amino acid composition similar to human collagen, fish collagen peptides are widely used in food, health food, and functional nutritional formulations, especially in products related to skin health, where they have high application value.

[0003] Existing research and industry practice generally agree that the absorption and utilization efficiency of collagen peptides in the human body is closely related to their molecular weight and distribution characteristics. In applications related to skin nutrition support, peptides with excessively large molecular weights have lower utilization rates during digestion and absorption, while free amino acids or very short peptides with excessively small molecular weights fail to demonstrate the unique structural advantages and nutritional properties of collagen. Therefore, fish collagen peptides with a specific molecular weight range and relatively concentrated distribution are more suitable for applications related to improving skin's moisture retention and elasticity.

[0004] In existing technologies, fish collagen peptides are typically produced by pre-treating fish skin or scales through washing, defatting, and softening, followed by extraction using acid, alkaline, or enzymatic methods. The peptides are then further hydrolyzed using proteases. To control the degree of hydrolysis and the molecular weight distribution of the products, current methods mainly rely on selecting different types of proteases, adjusting the enzyme dosage, reaction temperature, and reaction time, or introducing post-processing techniques such as membrane separation, ultrafiltration, or fractional filtration after hydrolysis to separate and enrich peptides in different molecular weight ranges.

[0005] However, the above methods still have certain shortcomings in practical applications. On the one hand, controlling molecular weight distribution solely by adjusting enzymatic hydrolysis conditions is easily affected by factors such as differences in raw material sources and inhomogeneity of the reaction system. The hydrolysis reaction is difficult to maintain consistency within the system, often resulting in the presence of a large number of incompletely hydrolyzed large peptides and a high proportion of very low molecular weight peptides or free amino acids in the product, thus limiting the proportion of peptides in the target molecular weight range suitable for skin nutritional support applications. On the other hand, while post-processing methods such as membrane separation or fractional filtration can improve molecular weight distribution to some extent, they usually require increased equipment investment and energy consumption, making the process relatively complex and unfavorable for large-scale production and cost control.

[0006] Furthermore, fish scales, as a significant source of fish collagen, have a dense internal structure where collagen, mineral components, and keratin coexist. Different regions exhibit significant differences in protease accessibility during hydrolysis. Under conventional processing conditions, hydrolysis preferentially occurs in the surface area, while hydrolysis in the internal regions is relatively delayed, easily leading to uneven hydrolysis and further affecting the molecular weight distribution stability of the final fish collagen peptides. This distribution instability is particularly pronounced in applications aimed at improving skin hydration and elasticity.

[0007] Therefore, how to improve the preparation process of fish collagen peptides while ensuring safety and industrialization, so that the resulting products can stably obtain a molecular weight distribution more suitable for skin moisture retention and elasticity improvement applications, while avoiding over-reliance on complex post-processing processes, remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] This application provides a fish collagen peptide for improving skin moisture and elasticity and a method for preparing the same, aiming to solve the problem that the hydrolysis reaction is uneven and the molecular weight distribution of the product is difficult to control stably in the existing fish collagen peptide preparation process, resulting in a limited proportion of peptides in the target molecular weight range suitable for improving skin moisture and elasticity.

[0009] In a first aspect, this application provides a method for preparing fish collagen peptides for improving skin hydration and elasticity, comprising the following steps:

[0010] S1: Soak the fish scales in water to soften them, thus obtaining softened fish scales;

[0011] S2: The softened fish scales are soaked in a pretreatment solution containing a first polyol and a second polyol, so that the first polyol diffuses into the collagen layer of the fish scales and the second polyol forms a hydration layer on the outer layer of the fish scale collagen, thereby obtaining pretreated fish scales; wherein, the molecular weight of the first polyol is 60~120 Da and the molecular weight of the second polyol is 250~500 Da.

[0012] S3: The pretreated fish scales are hydrolyzed using an endopeptide protease to hydrolyze the fish collagen in the fish scales into fish collagen peptides, resulting in an enzymatic hydrolysate.

[0013] S4: The enzymatic hydrolysate is post-processed and dried to obtain fish collagen peptides for improving skin moisture and elasticity.

[0014] According to this application, by regulating the hydrolytic accessibility and reaction rate distribution of collagen in fish scales before the enzymatic hydrolysis reaction, the degradation of fish collagen during hydrolysis is made more uniform. This increases the mass ratio of low molecular weight peptides suitable for improving skin hydration and elasticity in the obtained fish collagen peptides without relying on complex post-separation processes, and improves the stability of the product's molecular weight distribution.

[0015] Specifically, the inventors discovered in their research that fish scales, as a source of collagen, exhibit a distinct layered structure and spatial variations within their internal structure. Collagen in fish scales is not distributed in a completely uniform morphology, but rather forms a dense structure together with mineral components and keratin. Under conventional direct enzymatic hydrolysis conditions, proteases tend to preferentially act on the surface region of the fish scales, while the hydrolysis reaction in the internal regions is relatively delayed due to limited diffusion, easily leading to spatial heterogeneity in the hydrolysis process. This heterogeneous hydrolysis behavior further results in the presence of a large number of incompletely hydrolyzed large-molecule peptides and a high proportion of very low-molecular-weight peptides or free amino acids in the enzymatic hydrolysis products, thereby limiting the proportion of fish collagen peptides within the target molecular weight range.

[0016] Based on the above understanding, this application does not simply enhance the degree of hydrolysis by extending the enzymatic hydrolysis time or increasing the amount of enzyme, but rather starts from the substrate state before the enzymatic hydrolysis reaction occurs, regulating the reaction environment of collagen in fish scales during the hydrolysis process. In step S1, the fish scales are softened by soaking in water, allowing the scale structure to fully absorb water and relax to a certain extent, creating favorable conditions for subsequent processing.

[0017] In step S2, softened fish scales are immersed in a pretreatment solution containing both a first polyol and a second polyol, introducing polyol components with different diffusion behaviors. The first polyol, with a molecular weight in the range of 60-120 Da, has a smaller molecular weight and can diffuse into the collagen interlayer structure of the fish scales via aqueous channels, helping to improve the hydration state and reaction accessibility of the internal collagen regions. The second polyol, with a molecular weight in the range of 250-500 Da, has a larger molecular weight and is less likely to diffuse into the fish scales. It tends to accumulate in the outer and near-surface regions of the fish scale collagen, forming a hydration structure with water molecules through its polyhydroxyl structure, thus creating a transient hydration layer on the surface of the fish scales. This hydration layer buffers and limits the hydrolysis rate of the surface collagen in the initial stage of the subsequent enzymatic reaction. If the molecular weight is too high, the formed hydration layer may affect the efficiency of subsequent enzymatic hydrolysis.

[0018] Through the spatial differentiation of the first and second polyols, more similar hydrolysis reaction conditions can be formed between the internal and external regions of fish scales, thereby reducing the difference in hydrolysis rate between the surface and internal regions and enabling collagen in fish scales to participate in enzymatic hydrolysis more evenly as a whole.

[0019] In step S3, the pretreated fish scales are used as the substrate for enzymatic hydrolysis with endopeptidase. Since the pretreatment step has regulated the hydrolytic environment of collagen in the fish scales, the endopeptidase can act more evenly on collagen molecules in different spatial regions during hydrolysis, thereby reducing local over-hydrolysis or under-hydrolysis and facilitating the acquisition of fish collagen peptide products with a more concentrated molecular weight distribution. After post-treatment and drying, fish collagen peptides for improving skin moisture and elasticity are obtained.

[0020] In summary, this application achieves overall regulation of the hydrolysis reaction environment of fish scale collagen by introducing a polyol pretreatment step with differential diffusion behavior before enzymatic hydrolysis, thereby optimizing the control of the molecular weight distribution of fish collagen peptides. This provides a new preparation method for fish collagen peptides that are more suitable for improving skin hydration and elasticity.

[0021] In some embodiments, step S1 includes:

[0022] Soak fish scales in water at a mass ratio of 1:5~15 for 30~120 minutes at 40~55℃ to obtain softened fish scales.

[0023] In some of the above embodiments, by immersing the fish scales in water under the conditions described, the fish scales can fully absorb water and soften, which is beneficial to improving the overall hydration state and structural flexibility of the fish scales. This provides a more stable treatment basis for the subsequent polyol pretreatment and enzymatic hydrolysis steps, and helps to improve the controllability and consistency of the subsequent process.

[0024] In some implementations, step S2 includes:

[0025] The softened fish scales are soaked in a pretreatment solution containing a first polyol, which diffuses into the collagen layer of the fish scales. Then, a second polyol is added to the pretreatment solution, which forms a hydration layer on the outer layer of the fish scale collagen, thus obtaining pretreated fish scales.

[0026] In some of the above embodiments, by limiting the treatment sequence of the first and second polyols, the first polyol with a smaller molecular weight can fully utilize the aqueous channels formed after the fish scales absorb water and soften during the initial pretreatment stage to diffuse into the collagen interlayer structure of the fish scales, thereby improving the hydration state and reaction accessibility of the collagen regions inside the fish scales. Introducing the second polyol with a larger molecular weight after the first polyol has completed its diffusion process can avoid the second polyol hindering or diluting the diffusion behavior of the first polyol in the same treatment stage, allowing the two polyols to function separately in the inner and outer regions of the fish scales.

[0027] By employing the aforementioned sequential processing method, it is beneficial to establish a clearer division of labor between the internal and external regions of the fish scales. This allows the reaction environment of the internal collagen region and the external region of the pretreated fish scales to be more coordinated when entering the enzymatic hydrolysis step. This, in turn, helps to improve the uniformity of the subsequent enzymatic hydrolysis process and provides favorable conditions for obtaining fish collagen peptides with a more reasonable molecular weight distribution.

[0028] In some implementations, step S2 includes:

[0029] The pretreated fish scales are soaked in a pretreatment solution containing a first polyol at a mass ratio of 1:5 to 15 for 20 to 50 minutes at 35 to 45°C; then a second polyol is added to the pretreatment solution and the fish scales are soaked at 35 to 45°C for 20 to 50 minutes to obtain the pretreated fish scales.

[0030] The first polyol has a mass percentage content of 10wt% to 20wt% in the pretreatment solution, and the second polyol has a mass percentage content of 3wt% to 7wt% in the pretreatment solution.

[0031] In some of the above embodiments, by synergistically limiting the pretreatment temperature, soaking time, and polyol content, the first polyol can fully penetrate the interlayer region of fish scale collagen while maintaining the stability of the fish scale collagen structure. A temperature range of 35~45℃ is beneficial for increasing the diffusion rate of polyol molecules while avoiding irreversible denaturation of the fish scale collagen structure due to excessively high temperatures, thereby ensuring the integrity of the collagen within the fish scales.

[0032] The mass percentage of the first polyol in the pretreatment solution is controlled within the range of 10wt% to 20wt%. This helps to ensure the penetration driving force while avoiding a significant increase in system viscosity due to excessively high polyol concentration, which would affect the uniformity of its diffusion into the fish scales. Under these conditions, the first polyol can effectively improve the hydration state between the collagen layers of the fish scales, providing a more uniform reaction substrate environment for subsequent enzymatic hydrolysis.

[0033] After the diffusion treatment of the first polyol is completed, a second polyol with a mass percentage of 3wt% to 7wt% is introduced, which is mainly distributed in the outer layer of fish scale collagen and forms a stable hydration layer structure. This hydration layer can play a certain buffering and regulating role in the outer layer of fish scales during subsequent enzymatic hydrolysis, thereby helping to reduce the tendency of excessively rapid hydrolysis in the outer layer and making the hydrolysis process of the inner and outer collagen regions of fish scales more coordinated.

[0034] By synergistically setting the above pretreatment conditions, it is beneficial to improve the reaction uniformity of fish scale collagen during enzymatic hydrolysis without introducing additional chemical modification steps, thereby obtaining fish collagen peptides with a specific molecular weight range and relatively concentrated distribution.

[0035] In some embodiments, the first polyol comprises glycerol, and the second polyol comprises maltitol.

[0036] In some of the above embodiments, glycerol, as a polyol with a small molecular weight, has good hydrophilicity and molecular permeability. It can diffuse into the interlayer structure of fish scale collagen during the pretreatment stage, regulating the hydration environment around collagen molecules and helping to improve the accessibility and reaction uniformity of collagen in subsequent enzymatic hydrolysis. At the same time, glycerol has a stable molecular structure and is less likely to cause irreversible denaturation of collagen, making it suitable as a mild pretreatment additive for fish scale collagen.

[0037] Maltitol, as a polyol with a large molecular weight, has limited diffusion within fish scales and is mainly distributed in the outer layer of fish scale collagen. It can form a relatively stable hydration protective layer after pretreatment and during subsequent enzymatic hydrolysis, thereby buffering the rapid action of endopeptides on the surface collagen of fish scales to a certain extent. This helps to coordinate the hydrolysis process of collagen in different areas of fish scales and further improves the concentration of the molecular weight distribution of the obtained fish collagen peptides.

[0038] Furthermore, glycerol and maltitol are both commonly used polyols in the food industry, widely applied in food, health food, and functional food sectors, exhibiting good biocompatibility and safety. In the method of this application, the aforementioned polyols are primarily used in the pretreatment stage before enzymatic hydrolysis. Their action is mainly through physical osmosis and hydration regulation, without chemically reacting with fish collagen, introducing no new chemical structural units, and their content can be further reduced during subsequent enzymatic hydrolysis and post-treatment. Therefore, they will not adversely affect the safety of the final obtained fish collagen peptides.

[0039] In some implementations, step S3 includes:

[0040] The pretreated fish scales were dispersed in water at a mass ratio of 1:5 to 15. Based on the dry weight of the fish scales, 0.05 wt% to 0.3 wt% of endopeptidase was added. The mixture was hydrolyzed for 3 to 4 hours at a pH of 8.2 to 9.2 and a temperature of 55 to 62°C to obtain the hydrolysate.

[0041] In some of the above embodiments, by dispersing the pretreated fish scales in water under appropriate solid-liquid ratio conditions, it can be ensured that the fish scale particles fully contact the enzyme molecules in the enzymatic hydrolysis system, avoiding excessively high local concentrations or limited mass transfer, thereby facilitating the uniformity of the enzymatic hydrolysis reaction. The amount of endopeptide added is controlled within the range of 0.05wt% to 0.3wt%, ensuring sufficient hydrolysis of fish collagen. Controlling the pH of the enzymatic hydrolysis reaction at 8.2 to 9.2 and the temperature at 55 to 62°C allows the endopeptide to maintain a high level of enzyme activity and reaction stability, which is beneficial for the controlled hydrolysis of fish collagen in a shorter time. By limiting the hydrolysis time to 3 to 4 hours, the risk of further amplification of differences in the degree of collagen hydrolysis in different regions can be reduced while ensuring sufficient collagen breakdown, thus helping to obtain a fish collagen peptide hydrolysate with a relatively concentrated molecular weight distribution.

[0042] In some embodiments, in step S3, the endopeptide includes an Alcalase enzyme preparation.

[0043] In some of the above embodiments, the Alcalase enzyme preparation is a broad-spectrum endopeptide protease, which has good cleavage efficiency and applicability to collagen. It can stably achieve the hydrolysis of collagen under the conditions described in this application, which is beneficial to obtaining polypeptide products with a relatively concentrated molecular weight distribution.

[0044] In some implementations, step S4 includes:

[0045] After the enzyme hydrolysate is inactivated, it is filtered through a plate and frame filter. The filtrate is collected and decolorized with activated carbon. The decolorized filtrate is then concentrated by membrane and scraper. After the concentrate is sterilized by membrane filtration, it is spray-dried to obtain fish collagen peptides for improving skin moisture and elasticity.

[0046] In some of the above embodiments, the decolorized filtrate is subjected to membrane concentration and scraper concentration in sequence to gradually increase the solid content of the solution, thereby providing suitable feeding conditions for the subsequent drying process; then the concentrate is subjected to membrane filtration sterilization treatment to further improve the hygiene and safety of the product; finally, the treated liquid is converted into a powder product by spray drying to obtain fish collagen peptides for improving skin moisture and elasticity.

[0047] In the above embodiments, by performing reasonable post-treatment and drying of the enzymatic hydrolysate, the stability, storability and practical application suitability of the product can be improved without changing the molecular weight distribution characteristics of the peptides, making the obtained fish collagen peptides more suitable for use in food, nutritional supplements or skin-related products.

[0048] In this application, there are no further restrictions on the type of fish scale material; it can be fish scales from freshwater fish such as tilapia and carp.

[0049] Secondly, this application provides a fish collagen peptide for improving skin moisture and elasticity, prepared according to the method described in any embodiment of the first aspect.

[0050] According to this application, the fish collagen peptides are obtained by pretreatment of fish scale raw materials and enzymatic hydrolysis. The molecular weight distribution of the peptides is more concentrated, and they can be stably enriched in the low molecular weight range that is suitable for absorption and utilization. Therefore, in practical applications, they are more conducive to improving the skin's moisture retention and elasticity.

[0051] In some embodiments, the fish collagen peptide contains at least 60% low molecular weight peptides with a molecular weight of 180-1000 Da.

[0052] In the above embodiments, peptides with molecular weights in the range of 180-1000 Da generally have better solubility and bioavailability, making them more easily utilized during human digestion and absorption. Components with molecular weights below 180 Da are mainly composed of free amino acids or very short peptides, with relatively limited functional specificity, while peptides with molecular weights above 1000 Da are relatively difficult to absorb. By controlling the molecular weight distribution of fish collagen peptides within the above range, the overall application potential of the product in improving skin moisture retention and elasticity can be enhanced.

[0053] Compared with the prior art, the beneficial effects of this application are at least as follows:

[0054] This application improves the reaction consistency of the enzymatic hydrolysis substrate by performing targeted pretreatment on fish scale raw materials and then performing enzymatic hydrolysis to prepare fish collagen peptides. Without relying on complex post-separation processes, the molecular weight distribution of the obtained fish collagen peptides is more concentrated, and the mass proportion of low molecular weight peptides with molecular weight in the range of 180~1000 Da in the product can be stably increased.

[0055] Meanwhile, the preparation method employed in this application features mild process conditions and clear steps. The introduced processing components possess excellent food safety, are easily integrated with existing production processes, and are suitable for large-scale and continuous production. The resulting fish collagen peptides exhibit good overall performance in terms of solubility and molecular weight distribution. Their molecular weight characteristics better meet the application requirements of related products for collagen peptide raw materials, thus providing a suitable basis for improving skin moisture retention and elasticity in practical applications. Detailed Implementation

[0056] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0057] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0059] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0060] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0061] The fish scales come from the scales of tilapia that were purchased.

[0062] Example 1

[0063] Preparation of fish collagen peptides for improving skin hydration and elasticity:

[0064] Weigh 1000g (dry basis) of fish scales, which are then purified and simply cleaned before use.

[0065] Add purified water to the fish scales at a mass ratio of 1:10 (fish scales to water) and soak at 45°C for 60 minutes to allow the fish scales to fully absorb water and soften. Filter to obtain softened fish scales.

[0066] The softened fish scales were transferred to a pretreatment container, with the mass ratio of softened fish scales to pretreatment solution containing glycerol (molecular weight 92 Da) being 1:10, and the mass percentage of glycerol in the pretreatment solution being 15 wt%. The mixture was then soaked at 40°C for 30 min.

[0067] Subsequently, while maintaining the system temperature at 40°C, maltitol (molecular weight 344 Da) was added to the pretreatment solution to achieve a maltitol content of 5 wt% in the pretreatment solution. The solution was then soaked for another 30 minutes and filtered to obtain pretreated fish scales.

[0068] The pretreated fish scales were added to purified water and dispersed at a mass ratio of 1:10 to water, forming a homogeneous suspension under stirring. Based on the dry weight of the fish scales, 0.15 wt% Alcalase enzyme preparation was added to the system to adjust the pH to 8.8. The reaction temperature was controlled at 58°C, and the enzymatic hydrolysis reaction was carried out under constant temperature and stirring conditions for 3.5 hours to obtain the enzymatic hydrolysate.

[0069] After the enzymatic hydrolysis reaction is completed, the hydrolysate is rapidly heated to 90°C and held at that temperature for 10 minutes to completely inactivate the endopeptide, thus completing the enzyme inactivation process. After enzyme inactivation, the hydrolysate is cooled to below 60°C for later use.

[0070] Subsequently, the enzyme-inactivated hydrolysate is sent to a plate and frame filter for filtration, with the filtration pressure controlled at 0.3 MPa, to remove incompletely hydrolyzed residues and insoluble impurities, and the clear filtrate is collected.

[0071] Activated carbon was added to the filtrate at a concentration of 0.3 wt% of the filtrate mass, and the mixture was stirred at 60°C for 30 minutes to decolorize. After decolorization, the activated carbon was removed by plate and frame filtration to obtain a decolorized fish collagen peptide solution.

[0072] The decolorized solution is sent to a membrane concentration system for pre-concentration. During the concentration process, the operating temperature is controlled not to exceed 50°C, so that the solid content of the solution is increased to 25-30 wt%. Subsequently, the membrane-concentrated solution is sent to a scraped-film evaporator for further concentration. The evaporation temperature is controlled at 60°C, so that the solid content is increased to 35-40 wt%, resulting in a concentrated solution suitable for spray drying.

[0073] The concentrated liquid was filtered and sterilized through a membrane with a pore size of 0.22 μm. After sterilization, the liquid directly entered the spray drying process. The concentrated liquid was dried using a spray drying method, with the inlet air temperature controlled at 170°C and the outlet air temperature at 85°C. The resulting dried powder was collected, yielding fish collagen peptides for improving skin moisture and elasticity.

[0074] The molecular weight distribution of the fish collagen peptides obtained above was tested in accordance with GB 31645-2018 "National Food Safety Standard Collagen Peptides". The results showed that the mass proportion of low molecular weight peptides with a molecular weight in the range of 180~1000 Da in the fish collagen peptides was 67.71%.

[0075] Example 2

[0076] Preparation of fish collagen peptides for improving skin hydration and elasticity:

[0077] It is largely the same as Example 1, except that 1,2-propanediol (molecular weight 76 Da) is used instead of glycerol.

[0078] The molecular weight distribution of the fish collagen peptides obtained above was tested in accordance with GB 31645-2018 "National Food Safety Standard Collagen Peptides". The results showed that the mass proportion of low molecular weight peptides with a molecular weight in the range of 180~1000 Da in the fish collagen peptides was 63.98%.

[0079] Example 3

[0080] Preparation of fish collagen peptides for improving skin hydration and elasticity:

[0081] Weigh 1000g (dry basis) of fish scales, which are then purified and simply cleaned before use.

[0082] Add purified water to the fish scales at a mass ratio of 1:10 (fish scales to water) and soak at 45°C for 60 minutes to allow the fish scales to fully absorb water and soften. Filter to obtain softened fish scales.

[0083] The softened fish scales were transferred to a pretreatment container, with the mass ratio of softened fish scales to a pretreatment solution containing glycerol (molecular weight 92) and maltitol (molecular weight 344) at 1:10. The glycerol content in the pretreatment solution was 15 wt%, and the maltitol content was 5 wt%. The mixture was soaked at 40°C for 60 min; the pretreated fish scales were then obtained by filtration.

[0084] The pretreated fish scales were added to purified water and dispersed at a mass ratio of 1:10 to water, forming a homogeneous suspension under stirring. Based on the dry weight of the fish scales, 0.15 wt% Alcalase enzyme preparation was added to the system to adjust the pH to 8.8. The reaction temperature was controlled at 58°C, and the enzymatic hydrolysis reaction was carried out under constant temperature and stirring conditions for 3.5 hours to obtain the enzymatic hydrolysate.

[0085] After the enzymatic hydrolysis reaction is completed, the hydrolysate is rapidly heated to 90°C and held at that temperature for 10 minutes to completely inactivate the endopeptide, thus completing the enzyme inactivation process. After enzyme inactivation, the hydrolysate is cooled to below 60°C for later use.

[0086] Subsequently, the enzyme-inactivated hydrolysate is sent to a plate and frame filter for filtration, with the filtration pressure controlled at 0.3 MPa, to remove incompletely hydrolyzed residues and insoluble impurities, and the clear filtrate is collected.

[0087] Activated carbon was added to the filtrate at a concentration of 0.3 wt% of the filtrate mass, and the mixture was stirred at 60°C for 30 minutes to decolorize. After decolorization, the activated carbon was removed by plate and frame filtration to obtain a decolorized fish collagen peptide solution.

[0088] The decolorized solution is sent to a membrane concentration system for pre-concentration. During the concentration process, the operating temperature is controlled not to exceed 50°C, so that the solid content of the solution is increased to 25-30 wt%. Subsequently, the membrane-concentrated solution is sent to a scraped-film evaporator for further concentration. The evaporation temperature is controlled at 60°C, so that the solid content is increased to 35-40 wt%, resulting in a concentrated solution suitable for spray drying.

[0089] The concentrated liquid was filtered and sterilized through a membrane with a pore size of 0.22 μm. After sterilization, the liquid directly entered the spray drying process. The concentrated liquid was dried using a spray drying method, with the inlet air temperature controlled at 170°C and the outlet air temperature at 85°C. The resulting dried powder was collected, yielding fish collagen peptides for improving skin moisture and elasticity.

[0090] The molecular weight distribution of the fish collagen peptides obtained above was tested in accordance with GB 31645-2018 "National Food Safety Standard Collagen Peptides". The results showed that the mass percentage of low molecular weight peptides with a molecular weight in the range of 180~1000 Da was 65.49%.

[0091] Comparative Example 1

[0092] Preparation of fish collagen peptides for improving skin hydration and elasticity:

[0093] Weigh 1000g (dry basis) of fish scales, which are then purified and simply cleaned before use.

[0094] Add purified water to the fish scales at a mass ratio of 1:10 (fish scales to water) and soak at 45°C for 60 minutes to allow the fish scales to fully absorb water and soften. Filter to obtain softened fish scales.

[0095] The softened fish scales were added to purified water and dispersed at a mass ratio of 1:10 to water, forming a homogeneous suspension under stirring. Based on the dry weight of the fish scales, 0.15 wt% Alcalase enzyme preparation was added to the system to adjust the pH to 8.8. The reaction temperature was controlled at 58°C, and the enzymatic hydrolysis reaction was carried out under constant temperature and stirring conditions for 3.5 hours to obtain the enzymatic hydrolysate.

[0096] After the enzymatic hydrolysis reaction is completed, the hydrolysate is rapidly heated to 90°C and held at that temperature for 10 minutes to completely inactivate the endopeptide, thus completing the enzyme inactivation process. After enzyme inactivation, the hydrolysate is cooled to below 60°C for later use.

[0097] Subsequently, the enzyme-inactivated hydrolysate is sent to a plate and frame filter for filtration, with the filtration pressure controlled at 0.3 MPa, to remove incompletely hydrolyzed residues and insoluble impurities, and the clear filtrate is collected.

[0098] Activated carbon was added to the filtrate at a concentration of 0.3 wt% of the filtrate mass, and the mixture was stirred at 60°C for 30 minutes to decolorize. After decolorization, the activated carbon was removed by plate and frame filtration to obtain a decolorized fish collagen peptide solution.

[0099] The decolorized solution is sent to a membrane concentration system for pre-concentration. During the concentration process, the operating temperature is controlled not to exceed 50°C, so that the solid content of the solution is increased to 25-30 wt%. Subsequently, the membrane-concentrated solution is sent to a scraped-film evaporator for further concentration. The evaporation temperature is controlled at 60°C, so that the solid content is increased to 35-40 wt%, resulting in a concentrated solution suitable for spray drying.

[0100] The concentrated liquid was filtered and sterilized through a membrane with a pore size of 0.22 μm. After sterilization, the liquid directly entered the spray drying process. The concentrated liquid was dried using a spray drying method, with the inlet air temperature controlled at 170°C and the outlet air temperature at 85°C. The resulting dried powder was collected, yielding fish collagen peptides for improving skin moisture and elasticity.

[0101] The molecular weight distribution of the fish collagen peptides obtained above was tested in accordance with GB 31645-2018 "National Food Safety Standard Collagen Peptides". The results showed that the mass proportion of low molecular weight peptides with a molecular weight in the range of 180~1000 Da in the fish collagen peptides was 50.85%.

[0102] Comparative Example 2

[0103] Preparation of fish collagen peptides for improving skin hydration and elasticity:

[0104] It is largely the same as Example 1, except that sorbitol (molecular weight 182 Da) is used instead of glycerol.

[0105] The molecular weight distribution of the fish collagen peptides obtained above was tested in accordance with GB 31645-2018 "National Food Safety Standard Collagen Peptides". The results showed that the mass percentage of low molecular weight peptides with a molecular weight in the range of 180~1000 Da was 53.29%.

[0106] Comparative Example 3

[0107] Preparation of fish collagen peptides for improving skin hydration and elasticity:

[0108] Weigh 1000g (dry basis) of fish scales, which are then purified and simply cleaned before use.

[0109] Add purified water to the fish scales at a mass ratio of 1:10 (fish scales to water) and soak at 45°C for 60 minutes to allow the fish scales to fully absorb water and soften. Filter to obtain softened fish scales.

[0110] The softened fish scales were transferred to a pretreatment container at a mass ratio of 1:10 to a pretreatment solution containing glycerol (molecular weight 92 Da), with the glycerol content in the pretreatment solution being 15 wt%. The fish scales were then soaked at 40°C for 30 minutes.

[0111] The pretreated fish scales were added to purified water and dispersed at a mass ratio of 1:10 to water, forming a homogeneous suspension under stirring. Based on the dry weight of the fish scales, 0.15 wt% Alcalase enzyme preparation was added to the system to adjust the pH to 8.8. The reaction temperature was controlled at 58°C, and the enzymatic hydrolysis reaction was carried out under constant temperature and stirring conditions for 3.5 hours to obtain the enzymatic hydrolysate.

[0112] After the enzymatic hydrolysis reaction is completed, the hydrolysate is rapidly heated to 90°C and held at that temperature for 10 minutes to completely inactivate the endopeptide, thus completing the enzyme inactivation process. After enzyme inactivation, the hydrolysate is cooled to below 60°C for later use.

[0113] Subsequently, the enzyme-inactivated hydrolysate is sent to a plate and frame filter for filtration, with the filtration pressure controlled at 0.3 MPa, to remove incompletely hydrolyzed residues and insoluble impurities, and the clear filtrate is collected.

[0114] Activated carbon was added to the filtrate at a concentration of 0.3 wt% of the filtrate mass, and the mixture was stirred at 60°C for 30 minutes to decolorize. After decolorization, the activated carbon was removed by plate and frame filtration to obtain a decolorized fish collagen peptide solution.

[0115] The decolorized solution is sent to a membrane concentration system for pre-concentration. During the concentration process, the operating temperature is controlled not to exceed 50°C, so that the solid content of the solution is increased to 25-30 wt%. Subsequently, the membrane-concentrated solution is sent to a scraped-film evaporator for further concentration. The evaporation temperature is controlled at 60°C, so that the solid content is increased to 35-40 wt%, resulting in a concentrated solution suitable for spray drying.

[0116] The concentrated liquid was filtered and sterilized through a membrane with a pore size of 0.22 μm. After sterilization, the liquid directly entered the spray drying process. The concentrated liquid was dried using a spray drying method, with the inlet air temperature controlled at 170°C and the outlet air temperature at 85°C. The resulting dried powder was collected, yielding fish collagen peptides for improving skin moisture and elasticity.

[0117] The molecular weight distribution of the fish collagen peptides obtained above was tested in accordance with GB 31645-2018 "National Food Safety Standard Collagen Peptides". The results showed that the mass proportion of low molecular weight peptides with a molecular weight in the range of 180~1000 Da in the fish collagen peptides was 54.36%.

[0118] Comparative Example 4

[0119] Preparation of fish collagen peptides for improving skin hydration and elasticity:

[0120] Weigh 1000g (dry basis) of fish scales, which are then purified and simply cleaned before use.

[0121] Add purified water to the fish scales at a mass ratio of 1:10 (fish scales to water) and soak at 45°C for 60 minutes to allow the fish scales to fully absorb water and soften. Filter to obtain softened fish scales.

[0122] The softened fish scales were transferred to a pretreatment container, with the mass ratio of softened fish scales to pretreatment solution containing maltitol (molecular weight 344 Da) being 1:10, and the maltitol content in the pretreatment solution being 5 wt%. The fish scales were then soaked at 40°C for 30 minutes.

[0123] The pretreated fish scales were added to purified water and dispersed at a mass ratio of 1:10 to water, forming a homogeneous suspension under stirring. Based on the dry weight of the fish scales, 0.15 wt% Alcalase enzyme preparation was added to the system to adjust the pH to 8.8. The reaction temperature was controlled at 58°C, and the enzymatic hydrolysis reaction was carried out under constant temperature and stirring conditions for 3.5 hours to obtain the enzymatic hydrolysate.

[0124] After the enzymatic hydrolysis reaction is completed, the hydrolysate is rapidly heated to 90°C and held at that temperature for 10 minutes to completely inactivate the endopeptide, thus completing the enzyme inactivation process. After enzyme inactivation, the hydrolysate is cooled to below 60°C for later use.

[0125] Subsequently, the enzyme-inactivated hydrolysate is sent to a plate and frame filter for filtration, with the filtration pressure controlled at 0.3 MPa, to remove incompletely hydrolyzed residues and insoluble impurities, and the clear filtrate is collected.

[0126] Activated carbon was added to the filtrate at a concentration of 0.3 wt% of the filtrate mass, and the mixture was stirred at 60°C for 30 minutes to decolorize. After decolorization, the activated carbon was removed by plate and frame filtration to obtain a decolorized fish collagen peptide solution.

[0127] The decolorized solution is sent to a membrane concentration system for pre-concentration. During the concentration process, the operating temperature is controlled not to exceed 50°C, so that the solid content of the solution is increased to 25-30 wt%. Subsequently, the membrane-concentrated solution is sent to a scraped-film evaporator for further concentration. The evaporation temperature is controlled at 60°C, so that the solid content is increased to 35-40 wt%, resulting in a concentrated solution suitable for spray drying.

[0128] The concentrated liquid was filtered and sterilized through a membrane with a pore size of 0.22 μm. After sterilization, the liquid directly entered the spray drying process. The concentrated liquid was dried using a spray drying method, with the inlet air temperature controlled at 170°C and the outlet air temperature at 85°C. The resulting dried powder was collected, yielding fish collagen peptides for improving skin moisture and elasticity.

[0129] The molecular weight distribution of the fish collagen peptides obtained above was tested in accordance with GB 31645-2018 "National Food Safety Standard Collagen Peptides". The results showed that the mass proportion of low molecular weight peptides with a molecular weight in the range of 180~1000 Da in the fish collagen peptides was 53.95%.

[0130] The results of Examples 1-3 and Comparative Examples 1-4 show that the mass percentages of low molecular weight peptides (180-1000 Da) in the fish collagen peptides obtained in Examples 1-3 were 67.71%, 63.98%, and 65.49%, respectively, all higher than those in Comparative Examples 1-4 (50.85%, 53.29%, 54.36%, and 53.95%, respectively). This indicates that the process provided in this application can stably increase the mass percentage of peptides in the target molecular weight range of 180-1000 Da without relying on extending the enzymatic hydrolysis time or strengthening the separation process, thereby achieving effective control over the molecular weight distribution of the fish scale enzymatic hydrolysis products. A possible reason for this is that no polyol pretreatment was performed in Comparative Example 1, resulting in inconsistent hydrolysis progress between the inner and outer layers of the fish scale collagen structure, easily leading to simultaneous over-hydrolysis of the surface layer (increase in <180 Da) and insufficient hydrolysis of the interior. (>1000Da residue) resulted in a low proportion of the target range; in Comparative Example 2, sorbitol (molecular weight approximately 182Da) was used to replace the first polyol. Its molecular weight is 182Da, which is insufficient to diffuse into the collagen interlayer, making it difficult to form an effective "internal diffusion-external hydration" regional regulation, resulting in limited improvement; in Comparative Example 3, only the first polyol (glycerol) was used for treatment. Although it can promote interlayer swelling and improve the accessibility of the inner layer, it lacks the outer layer hydration shield and interface rate limiting effect. The surface layer may still undergo relatively faster hydrolysis, resulting in insufficient improvement of the target range; in Comparative Example 4, only the second polyol (maltitol) was used for treatment. It mainly acts on the outer layer to form a hydration layer, but it is insufficient to promote the opening and diffusion of the inner layer structure. The internal collagen is still relatively dense and hydrolyzes slowly, thus it is also difficult to significantly increase the proportion of 180~1000Da.

[0131] As shown in Examples 1 and 2, the type of the first polyol affects the effect of pretreatment on the diffusion and penetration of fish scale collagen between layers: when the second polyol is the same (maltitol) and the process conditions are consistent, Example 1 (67.71%), which uses glycerol (92 Da) as the first polyol, is better than Example 2 (63.98%), which uses 1,2-propanediol (76 Da). This indicates that within the molecular weight range of this application, different small molecule polyols have different hydrophilicity, hydrogen bond donor and acceptor capabilities, and effects on collagen interlayer hydration / swelling. Glycerol is more conducive to promoting the interlayer penetration and homogenization pretreatment in the first stage, thereby more effectively cooperating with the subsequent construction of the outer hydration layer and achieving an increase in the proportion of peptides in the target molecular weight range.

[0132] As shown in Examples 1 and 3, the order of polyol treatment (stepwise addition) has a significant effect on achieving synergistic regulation: Example 1 adopted a stepwise treatment of "firstly, the first polyol diffuses into the interlayer, and then the second polyol is added to form the outer hydration layer". Its proportion of 180~1000Da (67.71%) is higher than that of Example 3, where two polyols are treated in the same system at the same time (65.49%). This indicates that the stepwise order can reduce the influence of the second polyol on the permeation and diffusion of the first polyol under the same bath conditions, so that the first stage can more fully complete the interlayer penetration and structural relaxation. Then, the second stage constructs a hydration shield and rate-limiting environment in the outer layer, thereby more effectively reducing the difference in hydrolysis rate between the inner and outer layers, reducing the coexistence of over-hydrolysis and under-hydrolysis, and further increasing the mass proportion of peptides in the target molecular weight range.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 therein. Such 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 this application.

Claims

1. A method of preparing fish collagen peptides for improving skin moisture and elasticity, characterized by, Includes the following steps: S1: Soak the fish scales in water to soften them, thus obtaining softened fish scales; S2: The softened fish scales are soaked in a pretreatment solution containing a first polyol, allowing the first polyol to diffuse into the collagen layer of the fish scales; then a second polyol is added to the pretreatment solution, allowing the second polyol to form a hydration layer on the outer layer of the fish scale collagen, thus obtaining pretreated fish scales; wherein, the first polyol includes glycerol, and the second polyol includes maltitol. S3: The pretreated fish scales are enzymatically hydrolyzed using Alcalase enzyme preparation to hydrolyze the fish collagen in the fish scales into fish collagen peptides, resulting in an enzymatic hydrolysate. S4: The enzymatic hydrolysate is post-processed and dried to obtain fish collagen peptides for improving skin moisture and elasticity, wherein the mass percentage of low molecular weight peptides with a molecular weight of 180~1000 Da in the fish collagen peptides is more than 60%.

2. The method of claim 1, wherein, Step S1 includes: Soak fish scales in water at a mass ratio of 1:5~15 for 30~120 minutes at 40~55℃ to obtain softened fish scales.

3. The method of claim 1, wherein, Step S2 includes: The pretreated fish scales are soaked in a pretreatment solution containing a first polyol at a mass ratio of 1:5 to 15 for 20 to 50 minutes at 35 to 45°C; then a second polyol is added to the pretreatment solution and the fish scales are soaked at 35 to 45°C for 20 to 50 minutes to obtain the pretreated fish scales. The first polyol has a mass percentage content of 10wt% to 20wt% in the pretreatment solution, and the second polyol has a mass percentage content of 3wt% to 7wt% in the pretreatment solution.

4. The method of claim 1, wherein, Step S3 includes: The pretreated fish scales were dispersed in water at a mass ratio of 1:5 to 15. Based on the dry weight of the fish scales, 0.05 wt% to 0.3 wt% Alcalase enzyme preparation was added. The mixture was enzymatically hydrolyzed for 3 to 4 hours at a pH of 8.2 to 9.2 and a temperature of 55 to 62°C to obtain the enzymatic hydrolysate.

5. The method according to any one of claims 1 to 4, characterized in that, Step S4 includes: After the enzyme hydrolysate is inactivated, it is filtered through a plate and frame filter. The filtrate is collected and decolorized with activated carbon. The decolorized filtrate is then concentrated by membrane and scraper. After the concentrate is sterilized by membrane filtration, it is spray-dried to obtain fish collagen peptides for improving skin moisture and elasticity.