Antioxidant liquid collagen peptide as well as preparation process and application thereof

Abstract

The invention discloses an antioxidant liquid collagen peptide as well as a preparation process and application thereof, and particularly relates to the technical field of extraction of fish collagen peptides. Aiming at different characteristics of the fish skin, the fish scales and the fish bones, the preparation process adopts a differential treatment method: the fish skin is degreased and then is subjected to enzymolysis by adopting alkaline protease; freezing and grinding the fish scales, decalcifying citric acid, and performing enzymolysis by adopting collagenase; the fish bones are subjected to enzymolysis by neutral protease after being degreased and decalcified; the three enzymatic hydrolysates are mixed in proportion and then subjected to adsorption, multi-stage membrane filtration and low-temperature concentration, and the liquid collagen peptide with the solid content of 30%-40% is prepared, according to the scheme, the process operation is simple and convenient, extraction is conducted under the low-temperature condition, the oxidation resistance of the collagen peptide can be effectively reserved, and the raw material utilization rate is high.

Description

Technical Field

[0001] The present invention relates to the technical field of fish collagen peptide extraction, in particular to an antioxidant liquid collagen peptide and a preparation process and application thereof. Background Art

[0002] At present, the collagen extraction process of fish processing by-products (such as fish skin, fish scales, and fish bones) mostly adopts unified treatment of mixed raw materials, which has technical defects: on the one hand, the extraction rate of highly mineralized type I collagen in fish scales is low due to the lack of targeted decalcification and enzymatic hydrolysis, and the molecular weight distribution is too wide and not concentrated; on the other hand, the non-specific hydrolysis of traditional alkaline protease leads to low retention rate of some antioxidant active peptides, affecting the antioxidant properties of the final product. Summary of the Invention

[0003] The main purpose of the present invention is to provide an antioxidant liquid collagen peptide and its preparation process and application, so as to solve the technical problem that the collagen extraction process of fish processing by-products mostly adopts the unified treatment of mixed raw materials, resulting in the extracted collagen peptides having too wide molecular weight distribution and poor antioxidant effect.

[0004] To achieve the above object, the present invention provides a process for preparing an antioxidant liquid collagen peptide, comprising the following steps: S10, processing fish skin: after beating fish skin, mix with pure water to obtain fish skin slurry, degrease the fish skin slurry to obtain defatted fish skin slurry, add alkaline protease to the defatted fish skin slurry, and perform enzymolysis for the first time to obtain fish skin enzymolysis solution; S20, processing the fish scales: grinding the fish scales to obtain fish scale powder, mixing the fish scale powder with a food-grade citric acid aqueous solution to obtain a fish scale powder citric acid mixture, decalcifying, homogenizing, and filtering the fish scale powder citric acid mixture to obtain a decalcified fish scale solution, and adding collagenase to the decalcified fish scale solution for a second enzymatic hydrolysis to obtain a fish scale enzymatic hydrolyzate; S30, processing the fish bones: grinding the fish bones to obtain fish bone powder, mixing the fish bone powder with pure water to obtain a fish bone mixture, defatting, decalcifying, homogenizing, and filtering the fish bone mixture to obtain a defatted and decalcified fish bone solution, and adding a neutral protease to the defatted and decalcified fish bone solution for a third enzymatic hydrolysis to obtain a fish bone enzymatic hydrolyzate; S40, mixing the fish skin enzymatic hydrolysate, the fish scale enzymatic hydrolysate, and the fish bone enzymatic hydrolysate to obtain an enzymatic hydrolysate mixture, and adsorbing, filtering, and concentrating the enzymatic hydrolysate mixture to obtain antioxidant liquid collagen peptides.

[0005] In some embodiments of the present invention, the reaction temperature of the first enzymatic hydrolysis is 50° C. to 55° C., and the reaction time is 2 h to 3 h.

[0006] In some embodiments of the present invention, the temperature of the second enzymatic hydrolysis is 37° C. to 38° C., and the reaction time is 2 h to 3 h.

[0007] In some embodiments of the present invention, the enzymatic hydrolysis temperature of the third enzymatic hydrolysis is 50° C. to 55° C., and the enzymatic hydrolysis time is 1 h to 2 h.

[0008] In some embodiments of the present invention, the amount of alkaline protease added is 1% to 3% of the total mass of the defatted fish skin slurry; and / or the amount of collagenase added is 1% to 2% of the mass of the decalcified fish scale solution.

[0009] In some embodiments of the present invention, the added amount of the neutral protease is 1% to 2% of the mass of the defatted and decalcified fish bone solution.

[0010] In some embodiments of the present invention, in step S20, the homogenization includes a narrow-slit high-pressure homogenization method, and in step S30, the homogenization includes a narrow-slit high-pressure homogenization method.

[0011] In some embodiments of the present invention, the total solid content of the antioxidant liquid collagen peptide is 30% to 40%.

[0012] The present invention also provides an antioxidant liquid collagen peptide, which is prepared by the above-mentioned preparation process of the antioxidant liquid collagen peptide.

[0013] The present invention also provides a use of the antioxidant liquid collagen peptide described above in the fields of functional foods, health products and cosmetics.

[0014] The beneficial effects that can be achieved by the present invention are: The present invention provides a process for preparing antioxidant liquid collagen peptides, which significantly improves the quality and functionality of collagen peptides through differentiated processing methods.

[0015] The present invention utilizes targeted treatments tailored to the different characteristics of fish skin, scales, and bones: the skin is pulped and defatted before being hydrolyzed with alkaline protease, the scales are decalcified with citric acid and then treated with collagenase, and the bones are hydrolyzed with neutral protease after being defatted and decalcified. This not only fully releases the collagen in various fish by-products, but also effectively retains characteristic peptides with antioxidant activity, thereby enhancing the antioxidant properties of the final collagen peptides. The three enzymatic hydrolyses are then mixed in a scientifically formulated ratio, and impurities and odors are removed through adsorption, filtration, and concentration. The product is then concentrated to an appropriate concentration of 30% to 40% using cryogenic concentration technology. This allows the temperature to be consistently controlled at low temperatures throughout the entire process, maximizing the biological activity of the collagen peptides. The resulting liquid collagen peptide product exhibits outstanding advantages, including a narrow molecular weight distribution, low molecular weight, good solubility, and strong antioxidant activity. It also achieves high-value utilization of fish processing by-products, and has broad application prospects in functional foods, health products, and cosmetics. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0017] Figure 1 The figure is a schematic diagram of the process for preparing the antioxidant liquid collagen peptide of the present invention.

[0018] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0019] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] In this disclosure, terms such as "first," "second," and so on are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features designated as "first" or "second" may explicitly or implicitly include at least one such feature. Furthermore, the technical solutions of various embodiments may be combined, but only if they are achievable by persons of ordinary skill in the art. If a combination of technical solutions contradicts or is unachievable, such combination shall be deemed non-existent and outside the scope of protection claimed by this disclosure.

[0022] The present invention provides an antioxidant liquid collagen peptide and its preparation process, referring to Figure 1 , the preparation process comprises the following steps: S10, processing fish skin: after beating fish skin, mix with pure water to obtain fish skin slurry, degrease the fish skin slurry to obtain defatted fish skin slurry, add alkaline protease to the defatted fish skin slurry, and perform enzymolysis for the first time to obtain fish skin enzymolysis solution; S20, processing the fish scales: grinding the fish scales to obtain fish scale powder, mixing the fish scale powder with a food-grade citric acid aqueous solution to obtain a fish scale powder citric acid mixture, decalcifying, homogenizing, and filtering the fish scale powder citric acid mixture to obtain a decalcified fish scale solution, and adding collagenase to the decalcified fish scale solution for a second enzymatic hydrolysis to obtain a fish scale enzymatic hydrolyzate; S30, processing the fish bones: grinding the fish bones to obtain fish bone powder, mixing the fish bone powder with pure water to obtain a fish bone mixture, defatting, decalcifying, homogenizing, and filtering the fish bone mixture to obtain a defatted and decalcified fish bone solution, and adding a neutral protease to the defatted and decalcified fish bone solution for a third enzymatic hydrolysis to obtain a fish bone enzymatic hydrolyzate; S40, mixing the fish skin enzymatic hydrolysate, the fish scale enzymatic hydrolysate, and the fish bone enzymatic hydrolysate to obtain an enzymatic hydrolysate mixture, and adsorbing, filtering, and concentrating the enzymatic hydrolysate mixture to obtain antioxidant liquid collagen peptides.

[0023] The present invention utilizes targeted treatments tailored to the different characteristics of fish skin, scales, and bones: the skin is pulped and defatted before being hydrolyzed with alkaline protease, the scales are decalcified with citric acid and then treated with collagenase, and the bones are defatted and decalcified before being hydrolyzed with a neutral protease. This not only fully releases the collagen present in various fish by-products, but also effectively retains characteristic peptides with antioxidant activity, thereby enhancing the antioxidant properties of the final collagen peptides. The three enzymatic hydrolyses are then mixed in a scientifically formulated ratio, and impurities and odors are removed through adsorption, filtration, and concentration. The product is then concentrated to an appropriate concentration of 30% to 40% using cryogenic concentration technology. This allows the temperature to be consistently controlled at low temperatures throughout the entire process, maximizing the biological activity of the collagen peptides. The resulting liquid collagen peptide product exhibits outstanding advantages, including a narrow molecular weight distribution, low molecular weight, good solubility, and strong antioxidant activity. It also achieves high-value utilization of fish processing by-products, and has broad application prospects in functional foods, health supplements, and cosmetics.

[0024] The collagen fiber structure of fish skin is relatively loose and has a high lipid content. Alkaline protease is more active under pH 9-11 conditions. Enzymatic hydrolysis after defatting can effectively hydrolyze collagen and non-collagen proteins, saponified residual lipids in fish skin, and also destroy disulfide bonds, open the spatial structure of the protein, and obtain high-purity, small molecular weight and more concentrated collagen polypeptides.

[0025] Fish scales contain a large amount of calcium and phosphate, and have a highly mineralized and cross-linked rigid structure. The presence of these components will affect the enzymatic hydrolysis effect. Therefore, decalcification followed by enzymatic hydrolysis can effectively improve the enzymatic hydrolysis effect and efficiency. The selected hydrolase collagenase can not only specifically hydrolyze the peptide bonds of collagen, but also has good tolerance to calcium and phosphate, and is not easily affected by the calcium in it. The hydrolysis effect and efficiency are conducive to obtaining collagen peptides with a smaller molecular weight and a more concentrated distribution, and the antioxidant properties of collagen peptides are retained as much as possible.

[0026] Fish bones contain a large amount of calcium and protein and have a relatively hard structure. The present invention first decalcifies the fish bones, which can effectively remove the influence of calcium on enzymatic hydrolysis. The selected neutral protease has high activity under neutral conditions and can effectively hydrolyze the protein in the fish bones.

[0027] In some embodiments, the pH of the fish skin slurry is adjusted to 7.0-7.5, and then lipase is added for hydrolysis to obtain a defatted fish skin slurry, which is beneficial to improving the degreasing efficiency and effect.

[0028] In some embodiments, after adding alkaline protease to the defatted fish skin slurry, the pH of the system is adjusted to 9-11, which is beneficial to improving the efficiency and effect of enzymatic hydrolysis.

[0029] In some embodiments, the reaction temperature of the first enzymatic hydrolysis is 50° C. to 55° C., and the reaction time is 2 h to 3 h.

[0030] In some embodiments, after the first enzymatic hydrolysis is completed, the enzyme is inactivated at 80°C to 85°C for 5 min to 10 min, and then the temperature is rapidly lowered to 25°C to 28°C to maintain the activity of the collagen.

[0031] In some embodiments, the amount of alkaline protease added is 1% to 3% of the total mass of the defatted fish skin slurry.

[0032] The collagen and hydroxyapatite in fish scales are interspersed and distributed in layers. Therefore, grinding and decalcifying the fish scales can expose the collagen, and then enzymatic hydrolysis can effectively increase the collagen extraction rate.

[0033] In some embodiments, fish scales are ground to obtain fish scale powder, and the average particle size of the fish scale powder is 0.5 mm to 1 mm, which is beneficial to improving decalcification efficiency.

[0034] In some embodiments, the fish scales are ground after being frozen, and the fish scales can be frozen using liquid nitrogen. Freezing the fish scales before grinding can effectively maintain the brittleness of the fish scales and prevent thermal denaturation during the grinding process, thereby improving the fineness and uniformity of the fish scale powder, and also helping to improve the efficiency of subsequent decalcification and enzymatic hydrolysis processes.

[0035] The invention mixes fish scale powder and food-grade citric acid aqueous solution. The citric acid can chemically react with calcium salt in the fish scale to generate soluble calcium citrate, thereby dissolving calcium from the fish scale.

[0036] In some embodiments, during the decalcification process, the fish scale powder and citric acid mixture is ultrasonically treated to promote the dissolution of calcium.

[0037] In some embodiments, ultrasonic treatment of the fish scale powder and citric acid mixture at 4° C. to 5° C. can reduce ultrasonic heat generation and protein damage.

[0038] In some embodiments, the frequency of ultrasound is 35 kHz to 45 kHz, and may be 40 kHz, and the power is 90 W to 110 W, and may be 100 W.

[0039] In some embodiments, real-time monitoring of Ca during ultrasonic decalcification 2+ When the concentration of Ca 2+ <80 mg L -1 , stop ultrasonic treatment and proceed to homogenization.

[0040] In the present invention, homogenization treatment is performed after decalcification. The homogenization process can be assisted by high pressure and low temperature treatment combined with pulse current, which can effectively break up hydroxyapatite and keep the collagen structure intact, significantly improving the decalcification effect and subsequent enzymatic hydrolysis efficiency.

[0041] In some embodiments, the homogenization method includes a slit high-pressure homogenization method, the homogenization temperature is 3°C to 5°C, and may be 4°C, and the pressure is 45MPa to 55MPa, and may be 50MPa.

[0042] In some embodiments, pulse current is added during homogenization to accelerate the fragmentation of hydroxyapatite.

[0043] In some embodiments, the homogenization time is 25 min to 30 min.

[0044] In some embodiments, filtration is performed through an ultrafiltration membrane with a pore size of 5 kDa, and deionized water is circulated 3 to 4 times, which is beneficial for washing away citric acid and free calcium in the decalcified slurry and retaining relatively intact proteins.

[0045] In some embodiments, the pH of the decalcified fish scale solution is adjusted to 7.5-7.8, and then collagenase is added for enzymatic hydrolysis. The present invention uses collagenase to enzymatically hydrolyze the decalcified fish scale solution instead of alkaline protease or neutral protease, because collagenase can specifically recognize and cut the Gly-XY triple helix structure unique to collagen, and is particularly suitable for processing the highly cross-linked type I collagen network in fish scales. It can efficiently release functional peptides with a molecular weight of 1kDa-3kDa. Compared with non-specific proteases such as alkaline protease or neutral protease, its enzymatic hydrolysis products are richer in the antioxidant activity core sequence Gly-Pro-Hyp, and can avoid the generation of bitter peptides caused by excessive hydrolysis. In addition, under weak alkaline conditions of pH 7.5, collagenase activity is optimal, which matches the physical properties of the decalcified fish scale solution, can fully deconstruct collagen fibers, and can reduce the destruction of key amino acids such as hydroxyproline, thereby enhancing the antioxidant activity of the final product.

[0046] In some embodiments, the temperature of the second enzymatic hydrolysis is 37° C. to 38° C., and the reaction time is 2 h to 3 h.

[0047] In some embodiments, after the second enzymatic hydrolysis is completed, the enzyme is inactivated at 50° C. to 55° C. for 5 to 10 minutes to help maintain the activity of the peptide.

[0048] In some embodiments, the amount of collagenase added is 1% to 2% of the mass of the decalcified fish scale solution.

[0049] In some embodiments, the ratio of fish scales to food-grade citric acid aqueous solution is 100:(100-200) g / ml.

[0050] The present invention has relatively mild treatment conditions for fish scales, and can achieve the purpose of decalcification to expose proteins with relatively complete structures.

[0051] Fish bones and scales are both rich in hydroxyapatite, and decalcification can improve collagen extraction. Fish bones generally have a higher fat content than scales. Therefore, when processing fish bones, degreasing is performed first, followed by decalcification. Removing the fat layer surrounding the bones helps expose the hydroxyapatite structure and improve the efficiency of subsequent decalcification.

[0052] In some embodiments, fish bones are crushed to obtain fish bone powder, and the particle size of the fish bone powder is 1 mm to 2 mm.

[0053] In some embodiments, the ratio of fish bone powder to pure water is 100:(100-200) g / ml.

[0054] In some embodiments, the defatting of fish bones comprises: adding lipase to the fish bone mixture for defatting.

[0055] In some embodiments, the amount of lipase added to the fish bone mixture is 0.5% to 1.5% of the mass of the fish bone mixture.

[0056] In some embodiments, the decalcification treatment of fish bones includes: adding food-grade citric acid to the defatted fish bone mixture to obtain a fish bone powder citric acid mixture, and ultrasonically treating the fish bone powder citric acid mixture.

[0057] In some embodiments, during the decalcification process, the fish scale powder and citric acid mixture is ultrasonically treated to promote the dissolution of calcium.

[0058] In some embodiments, ultrasonic treatment of the fish scale powder and citric acid mixture at 4° C. to 5° C. can reduce ultrasonic heat generation and protein damage.

[0059] In some embodiments, the frequency of ultrasound is 35 kHz to 45 kHz, and may be 40 kHz, and the power is 90 W to 110 W, and may be 100 W.

[0060] In some embodiments, real-time detection of Ca during ultrasonic decalcification 2+ When the concentration of Ca 2+ <50 mg L -1 , stop ultrasonic treatment and proceed to homogenization.

[0061] In the present invention, homogenization is performed after defatting and decalcification. The homogenization process can effectively break up hydroxyapatite and keep the collagen structure intact, thereby significantly improving the decalcification effect and subsequent enzymatic hydrolysis efficiency.

[0062] In some embodiments, the homogenization method includes a slit high-pressure homogenization method, the homogenization temperature is 3°C to 5°C, and may be 4°C, and the pressure is 45MPa to 55MPa, and may be 50MPa.

[0063] In some embodiments, pulse current is added during homogenization to accelerate the fragmentation of hydroxyapatite.

[0064] In some embodiments, the homogenization time is 25 min to 30 min.

[0065] In some embodiments, filtration is performed through an ultrafiltration membrane with a pore size of 5 kDa, and deionized water is circulated 3 to 4 times, which is beneficial for washing away citric acid and free calcium in the decalcified slurry and retaining relatively intact proteins.

[0066] In some embodiments, the enzymatic hydrolysis temperature of the third enzymatic hydrolysis is 50° C. to 55° C., and the enzymatic hydrolysis time is 1 h to 2 h.

[0067] In some embodiments, the amount of neutral protease added is 1% to 2% of the mass of the defatted and decalcified fish bone solution.

[0068] In some embodiments, the mixed enzymatic hydrolysate is subjected to adsorption treatment with activated carbon to achieve the effects of deodorization and impurity removal. In some embodiments, the mass ratio of fish skin enzymatic hydrolysate: fish scale enzymatic hydrolysate: fish bone enzymatic hydrolysate is 5:(2~3):(2~3).

[0069] In some embodiments, the filtration step includes: graded membrane treatment: the first step of filtration: filtration using a ceramic membrane with a pore size of 0.1 μm and a filtration temperature of 40°C to remove unhydrolyzed particles; the second step of filtration: filtration using an ultrafiltration membrane with a molecular cutoff of 10 KDa, filtration at 25°C, and a tangential flow rate of 5 m / s, which can separate large molecular impurities; the third step of filtration: filtration using a nanofiltration membrane with a molecular cutoff of 1 KDa, filtration at 35°C to achieve desalination and concentration effects.

[0070] In some embodiments, the concentration includes: obtaining a collagen solution with a total solid content of 30% to 40% by low-temperature vacuum concentration, where the content refers to the mass percentage.

[0071] In some embodiments, low-temperature vacuum concentration is performed as follows: concentration is performed using a rotary evaporator at 40° C. and 100 mbar.

[0072] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not used to limit the present invention.

[0073] Example 1 The preparation process of the antioxidant liquid collagen peptide of this embodiment is as follows: S10: Take 1000g of tilapia skin and use a beater to break the skin into a pulp. Add 1500g of pure water and mix well to make fish skin slurry. Add lipase (1% by weight of the fish skin slurry) to the fish skin slurry, adjust the pH to 7.2, and perform degreasing at 50°C for 1 hour. After degreasing, adjust the pH to 9-11, then add alkaline protease (2% by weight of the fish skin slurry) and perform a first enzymatic hydrolysis reaction in a constant temperature water bath at 55°C for 2.5 hours to obtain a fish skin hydrolyzate.

[0074] S20, take 1000g fish scales, first use liquid nitrogen for freezing treatment, and then use a grinder to grind the frozen fish scales into fish scale powder with an average particle size of 0.8mm. The fish scale powder is evenly mixed with 1500g of a food-grade citric acid aqueous solution with a mass fraction of 5%, placed in a 4°C environment, and decalcified using an ultrasonic device with a frequency of 40kHz and a power of 100W. The calcium ion concentration in the solution is monitored in real time, and decalcification is stopped when the calcium ion concentration is lower than 80mg / L. The decalcified mixed solution is subjected to high-pressure homogenization at a pressure of 50MPa, and a decalcified fish scale solution is obtained after filtration. Collagenase of 1.5% of the solution mass is added to the decalcified fish scale solution, the pH value is adjusted to 7.5, and a second enzymatic hydrolysis reaction is carried out for 2.5 hours under a constant temperature water bath at 37.5°C to obtain a fish scale enzymatic hydrolyzate.

[0075] S30: Take 1000g of fish bones and grind them into fish bone powder with an average particle size of 1.5mm using a grinder. Mix the fish bone powder with 1500g of pure water. Add 1% lipase (by weight) to the mixture, adjust the pH to 7.2, and degrease at 50°C for 1 hour. After degreasing, add 5% food-grade citric acid. Decalcify the mixture at 4°C using an ultrasonic device with a frequency of 40kHz and a power of 100W. Monitor the calcium ion concentration in the solution in real time and stop decalcifying when the calcium ion concentration falls below 50mg / L. High-pressure homogenize the decalcified mixture at 50MPa and filter to obtain a defatted and decalcified fish bone solution. Add 1% neutral protease (by weight) to the defatted and decalcified fish bone solution. Perform a third enzymatic hydrolysis reaction in a constant temperature water bath at 55°C for 1.5 hours to obtain a fish bone hydrolyzate.

[0076] S40: The fish skin enzymatic hydrolysate, fish scale enzymatic hydrolysate and fish bone enzymatic hydrolysate prepared above are evenly mixed in a mass ratio of 5:3:2 to obtain an enzymatic hydrolysate mixture. The enzymatic hydrolysate mixture is adsorbed by an activated carbon adsorption column, and then filtered through a ceramic membrane with a pore size of 0.1 μm, an ultrafiltration membrane with a molecular weight cutoff of 10 KDa, and a nanofiltration membrane with a molecular weight cutoff of 1 KDa for three-stage filtration. Finally, the filtered solution is concentrated under low temperature vacuum using a rotary evaporator at 40°C until the total solid content in the solution reaches 35%, thereby obtaining a light yellow transparent liquid collagen peptide product.

[0077] Example 2 Example 2 An antioxidant liquid collagen peptide was prepared by referring to the preparation process of Example 1, except that, in Example 2, the amount of alkaline protease added was changed to 3% of the mass of the defatted fish skin slurry, the enzymatic hydrolysis temperature was adjusted to 50°C, and other conditions remained unchanged.

[0078] Example 3 Example 3 An antioxidant liquid collagen peptide was prepared by referring to the preparation process of Example 1, except that, in Example 3, the amount of collagenase added was changed to 1% of the mass of the decalcified fish scale solution, the enzymatic hydrolysis time was extended to 3 hours, and other conditions remained unchanged.

[0079] Example 4 Example 4 An antioxidant liquid collagen peptide was prepared by referring to the preparation process of Example 1, except that, in Example 4, the enzymatic hydrolysis temperature of the neutral protease was adjusted to 50° C., the enzymatic hydrolysis time was extended to 2 hours, and other conditions remained unchanged.

[0080] Example 5 Example 5 An antioxidant liquid collagen peptide was prepared by referring to the preparation process of Example 1, except that, in Example 5, the mixing ratio of the three enzymatic hydrolysates was adjusted to fish skin: fish scale: fish bone = 6:2:2, and the solid content at the concentration endpoint was adjusted to 30%, while other conditions remained unchanged.

[0081] Comparative Example 1 Comparative Example 1 Liquid collagen was prepared according to the scheme of Example 1, but specifically, in Comparative Example 1, fish skin, fish scales, and fish bones were mixed, crushed, stirred, and then pure water was added and mixed to obtain a fish feed mixture, followed by degreasing and decalcification with reference to the degreasing and decalcification steps of step S30 of Example 1, and high-pressure homogenization and filtration to obtain a defatted and decalcified fish feed mixture; Referring to the enzymatic hydrolysis process of Example 1, the defatted and decalcified fish feed mixture was enzymatically hydrolyzed three times with alkaline protease, collagenase, and neutral protease to obtain an enzymatic hydrolysis mixture. The enzymatic hydrolysis mixture was subjected to the adsorption, filtration, and concentration steps of step S40 of Example 1 to obtain an antioxidant liquid collagen peptide with a total solid content of 35%.

[0082] Performance Testing 1. Determine the percentage (%) of liquid collagen peptides with a molecular weight of 1kDa~10kDa.

[0083] 2. Antioxidant performance test: The liquid collagen peptides prepared in Examples 1 to 5 and Comparative Example 1 were prepared into 10 mg / ml sample aqueous solutions. 200 μL of the sample solutions were added to a 96-well plate and mixed with an equal volume of 0.1 mmol / L LDPPH ethanol solution. The mixture was reacted at room temperature in the dark for 30 minutes, and the absorbance of the reaction solution at 517 nm was measured.

[0084] Set up a control group: replace the DPPH ethanol solution in each group with anhydrous ethanol as the corresponding control group.

[0085] Set up blank groups: replace the sample aqueous solution in each group with deionized water as the corresponding blank group.

[0086] Set up the solvent group: a mixed solution of equal volumes of anhydrous ethanol and deionized water was used as the solvent group.

[0087] The absorbance of each reaction solution was measured respectively, and the calculation formula of DPPH free radical scavenging rate was as follows: DPPH free radical scavenging rate (%) = 1-(A0-A2 / A1-A3) × 100%; Among them, the experimental group was A0, the blank group was A1, the control group was A2, and the solvent group was A3.

[0088] Table 1

[0089] As can be seen from Table 1, the present invention pre-treats and enzymolyzes fish skin, fish scales, and fish bones, and finally obtains liquid collagen peptides with a smaller molecular weight, a more concentrated distribution, better preservation of antioxidant peptide segments, and stronger antioxidant capacity through adsorption, filtration, and concentration.

[0090] In Comparative Example 1, fish processing by-products such as fish skin, fish scales, and fish bones were mixed and processed uniformly, and the antioxidant capacity of the obtained liquid collagen peptide was significantly reduced.

[0091] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A process for preparing an antioxidant liquid collagen peptide, characterized in that: The following steps are involved: S10, processing fish skin: after beating fish skin, mix with pure water to obtain fish skin slurry, degrease the fish skin slurry to obtain defatted fish skin slurry, add alkaline protease to the defatted fish skin slurry, and perform enzymolysis for the first time to obtain fish skin enzymolysis solution; S20, processing the fish scales: grinding the fish scales to obtain fish scale powder, mixing the fish scale powder with a food-grade citric acid aqueous solution to obtain a fish scale powder citric acid mixture, decalcifying, homogenizing, and filtering the fish scale powder citric acid mixture to obtain a decalcified fish scale solution, and adding collagenase to the decalcified fish scale solution for a second enzymatic hydrolysis to obtain a fish scale enzymatic hydrolyzate; S30, processing the fish bones: grinding the fish bones to obtain fish bone powder, mixing the fish bone powder with pure water to obtain a fish bone mixture, defatting, decalcifying, homogenizing, and filtering the fish bone mixture to obtain a defatted and decalcified fish bone solution, and adding a neutral protease to the defatted and decalcified fish bone solution for a third enzymatic hydrolysis to obtain a fish bone enzymatic hydrolyzate; S40, mixing the fish skin enzymatic hydrolysate, the fish scale enzymatic hydrolysate, and the fish bone enzymatic hydrolysate to obtain an enzymatic hydrolysate mixture, and adsorbing, filtering, and concentrating the enzymatic hydrolysate mixture to obtain antioxidant liquid collagen peptides.

2. The process for preparing the antioxidant liquid collagen peptide according to claim 1, characterized in that: The reaction temperature of the first enzymatic hydrolysis is 50° C. to 55° C., and the reaction time is 2 h to 3 h.

3. The process for preparing the antioxidant liquid collagen peptide according to claim 1, characterized in that: The temperature of the second enzymatic hydrolysis is 37° C. to 38° C., and the reaction time is 2 h to 3 h.

4. The process for preparing the antioxidant liquid collagen peptide according to claim 1, characterized in that: The enzymatic hydrolysis temperature of the third enzymatic hydrolysis is 50° C. to 55° C., and the enzymatic hydrolysis time is 1 h to 2 h.

5. The process for preparing the antioxidant liquid collagen peptide according to claim 1, characterized in that: The addition amount of the alkaline protease is 1% to 3% of the total mass of the defatted fish skin slurry, and the addition amount of the collagenase is 1% to 2% of the mass of the decalcified fish scale solution.

6. The process for preparing the antioxidant liquid collagen peptide according to claim 1, characterized in that: The added amount of the neutral protease is 1% to 2% of the mass of the defatted and decalcified fish bone solution.

7. The process for preparing the antioxidant liquid collagen peptide according to claim 1, characterized in that: In the step S20, the homogenization is performed by a narrow-slit high-pressure homogenization method. In the step S30, the homogenization is performed by a narrow-slit high-pressure homogenization method.

8. The process for preparing the antioxidant liquid collagen peptide according to claim 1, characterized in that: The total solid content of the antioxidant liquid collagen peptide is 30% to 40%.

9. An antioxidant liquid collagen peptide, characterized in that: The antioxidant liquid collagen peptide is prepared by the preparation process of the antioxidant liquid collagen peptide according to any one of claims 1 to 8.

10. Use of the antioxidant liquid collagen peptide according to claim 9 in the fields of functional foods, health products and cosmetics.

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