Bombay duck active peptide as well as preparation method and application thereof

Abstract

The invention provides a Bombay duck active peptide and a preparation method and application thereof, and belongs to the technical field of polypeptide processing and preparation.The preparation method of the Bombay duck active peptide comprises the following steps that 1, Bombay duck cream is subjected to enzymolysis, and then a fish cream enzymatic hydrolysate is obtained; (2) filtering the fish cream enzymatic hydrolysate to obtain clarified enzymatic hydrolysate; 3) performing vacuum concentration on the clarified enzymatic hydrolysate to obtain a concentrated solution; and 4) performing vacuum drying on the concentrated solution to obtain the active peptide of the Bombay duck. By adopting a drying mode of combining vacuum pre-concentration and vacuum drying with dehydration, the bad flavor of the Bombay duck polypeptide can be improved, the product flavor and sensory evaluation are good, the antioxidant activity is high, and the content of small-molecular-weight peptide is higher.

Description

Technical Field

[0001] The invention belongs to the technical field of polypeptide processing and preparation, and in particular relates to a dragon head fish active peptide and a preparation method and application thereof. Background Art

[0002] Dragon head fish (Harpadon nehereus) is a special economic fish in the East China Sea. It is rich in nutrition, with a protein content of up to 70%, and calcium and phosphorus content much higher than other traditional economic fish. However, its extremely high water content (more than 90%) makes the muscle protein of the fish extremely unstable and difficult to preserve for a long time; and the market products are still mainly fresh fish and dried products, with a single product category, so its development and utilization rate is low, resulting in a waste of resources.

[0003] Enzymatically converting dragonhead fish into fish protein hydrolysate and extracting active protein peptides is an effective method to improve its bioavailability. Drying is a key process to obtain stable enzymatic hydrolysates. Freeze drying, spray drying and vacuum drying are some of the more common drying methods. However, different drying conditions will lead to differences in the quality of the final product. Freeze drying can effectively retain nutrients, but its development is limited by high instrument costs and energy consumption. Spray drying is widely used in food, pharmaceutical and chemical industries due to its low operating cost and high processing efficiency, but high temperature may destroy heat-sensitive substances. The current existing drying methods cannot well retain the nutrients and flavor substances of dragonhead fish. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a dragon head fish active peptide with good flavor and strong antioxidant activity, and a preparation method and application thereof; the present invention adopts a drying method of vacuum pre-concentration, vacuum drying and combined dehydration, which can improve the bad flavor of the dragon head fish polypeptide itself, and the product flavor and sensory evaluation are good, the antioxidant activity is strong, and the content of small molecular weight peptides is higher.

[0005] The present invention provides a method for preparing a dragon fish active peptide, comprising the following steps:

[0006] 1) hydrolyzing the dragon fish paste to obtain a fish paste hydrolyzate;

[0007] 2) filtering the fish paste enzymatic hydrolysate to obtain a clarified enzymatic hydrolysate;

[0008] 3) vacuum concentrating the clarified enzymatic hydrolysate to obtain a concentrated solution;

[0009] 4) vacuum drying the concentrated solution to obtain the dragon fish active peptide;

[0010] Step 3) The temperature of the vacuum concentration is 40 to 50°C, and the pressure of the vacuum concentration is -0.05 to -0.15Mpa;

[0011] Step 4) The temperature of the vacuum drying is 80-110° C., and the pressure of the vacuum drying is 80-82 KPa.

[0012] Preferably, the vacuum concentration in step 3) is performed until the total solid content of the clarified enzymatic hydrolysate is ≧25%.

[0013] Preferably, the vacuum drying in step 4) is performed until the water content of the dragon fish active peptide is ≦5%.

[0014] Preferably, the enzymes used for enzymolysis in step 1) are papain and neutral protease; the mass ratio of the papain and neutral protease is 1:(1.5-2.5); and the total mass of the papain and neutral protease is 1-2% of the mass of the dragonhead fish paste.

[0015] Preferably, the enzymatic hydrolysis temperature is 50-60° C., and the enzymatic hydrolysis time is 5-6 hours.

[0016] Preferably, after the enzymatic hydrolysis, the enzyme is inactivated and centrifuged to obtain the fish paste enzymatic hydrolysate; the centrifugal speed is 8000-12000 rpm, and the centrifugal time is 8-12 min.

[0017] Preferably, the filtration in step 2) is pressure filtration, and the pore size of the filter membrane of the pressure filtration is 1 to 2 μm.

[0018] Preferably, the dragon head fish paste in step 1) is obtained by mixing the dragon head fish with water, crushing it, and passing it through a colloid mill.

[0019] The invention provides a dragon head fish active peptide prepared by the preparation method, wherein the mass percentage of the polypeptide with a molecular weight less than 1KDa in the dragon head fish active peptide is 40-60%.

[0020] The present invention also provides the use of the dragon head fish active peptide in the preparation of antioxidant functional food.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the preparation method of the dragon head fish active peptide provided by the present invention adopts a drying method of vacuum pre-concentration, vacuum drying and combined dehydration, and the prepared dragon head fish polypeptide has a higher content of small molecular weight peptides; the sensing value of saltiness and umami is low, and the bitterness is also greatly reduced, which can improve the bad flavor; it shows higher sensitivity to sulfides, aromatic components, organic sulfides and nitrogen oxides, and since these compounds have a low odor threshold, they can significantly promote the overall aroma of the final product. The antioxidant activity results show that compared with freeze drying and spray drying, the dragon head fish polypeptide prepared by vacuum drying has stronger antioxidant activity and has a very high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1The molecular weight distribution analysis results of the dragonhead fish polypeptides prepared in Example 1, Comparative Example 1 and Comparative Example 2;

[0023] Figure 2 The electronic tongue radar images of the dragonhead fish polypeptides prepared in Example 1, Comparative Example 1 and Comparative Example 2;

[0024] Figure 3 The electronic nose radar diagram of the dragonhead fish polypeptide prepared in Example 1, Comparative Example 1 and Comparative Example 2;

[0025] Figure 4 The DPPH scavenging activity of the dragonhead fish polypeptide prepared in Example 1, Comparative Example 1 and Comparative Example 2;

[0026] Figure 5 This is the reducing activity of the dragonhead fish polypeptide prepared in Example 1, Comparative Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0027] The invention provides a method for preparing active peptides from dragonhead fish, comprising the following steps: 1) enzymatically hydrolyzing dragonhead fish paste to obtain fish paste enzymatic hydrolysate; 2) filtering the fish paste enzymatic hydrolysate to obtain a clarified enzymatic hydrolysate; 3) vacuum concentrating the clarified enzymatic hydrolysate to obtain a concentrated solution; 4) vacuum drying the concentrated solution to obtain active peptides from dragonhead fish; the temperature of the vacuum concentration in step 3 is 40-50 DEG C, and the pressure of the vacuum concentration is -0.05--0.15Mpa; the temperature of the vacuum drying in step 4 is 80-110 DEG C, and the pressure of the vacuum drying is 80-82Kpa.

[0028] In the present invention, the fish paste hydrolyzate is obtained after enzymatic hydrolysis of the dragon head fish paste. In the present invention, the dragon head fish paste is obtained by mixing the dragon head fish with water, crushing it, and passing it through a colloid mill. In the present invention, the dragon head fish is preferably fish meat after removing the head, tail and internal organs; when the dragon head fish is in a frozen state, it is preferably thawed first. In the present invention, the mass ratio of the dragon head fish and water is preferably (8-12): (6-8), more preferably (9-11): 7, and further preferably 10:7; in the present invention, the crushing is preferably carried out by a chopper; after the crushing, the crushed material is passed through a colloid mill for shear homogenization to obtain the dragon head fish paste.

[0029] After obtaining the dragonhead fish paste, the present invention performs enzymolysis; the enzymes used for enzymolysis are preferably papain and neutral protease; the mass ratio of the papain and the neutral protease is preferably 1: (1.5-2.5), more preferably 1: (1.8-2.2), and further preferably 1: 2; the total mass of the papain and the neutral protease is preferably 1-2% of the mass of the dragonhead fish paste, more preferably 1.2-1.8%, and further preferably 1.5%. In the present invention, the temperature of the enzymolysis is preferably 50-60°C, more preferably 53-57°C, and more preferably 55°C; the time of the enzymolysis is preferably 5-6h, more preferably 5.2-5.8h, and more preferably 5.5h; the pH of the enzymolysis is preferably 6.8-7.2, and more preferably 6.9-7.1; preferably, the present invention performs enzyme inactivation and centrifugation after the enzymolysis to obtain fish paste enzymolysis liquid; the temperature of the enzyme inactivation is 90-100°C, and the time of the enzyme inactivation is 10-20min; the present invention performs centrifugation after the enzyme inactivation, and the speed of the centrifugation is preferably 8000-12000rpm, more preferably 9000-11000rpm, and more preferably 10000rpm; the time of the centrifugation is preferably 8-12min, more preferably 9-11min, and more preferably 10min. The present invention collects the supernatant after the centrifugation to obtain the fish paste enzymolysis liquid.

[0030] In the invention, the fish paste enzymatic hydrolysate is filtered to obtain a clarified enzymatic hydrolysate; the filtration is preferably a filter press, and the pore size of the filter membrane of the filter press is preferably 1 to 2 μm, and more preferably 1 μm; the function of the filter press is to remove excess impurities and unhydrolyzed proteins.

[0031] After obtaining the clarified enzymatic hydrolysate, the present invention vacuum concentrates the clarified enzymatic hydrolysate to obtain a concentrated solution. In the present invention, the temperature of the vacuum concentration is preferably 40 to 50°C, more preferably 43 to 47°C, and more preferably 45°C; the pressure of the vacuum concentration is preferably -0.05 to -0.15Mpa, more preferably -0.08 to -0.125Mpa, and more preferably -0.10Mpa. In the present invention, the vacuum concentration is preferably concentrated to a total solid content of ≧25% in the clarified enzymatic hydrolysate. The present invention adopts vacuum concentration for concentration, which has the advantages of high concentration efficiency and prevention of loss of heat-sensitive substances.

[0032] After obtaining the concentrated solution, the present invention vacuum dries the concentrated solution to obtain the dragon head fish active peptide; in the present invention, the temperature of the vacuum drying is 80-110°C, preferably 85-95°C, and more preferably 90°C; the pressure of the vacuum drying is 80-82Kpa, preferably 80.5-81.5Kpa, and more preferably 81.3Kpa. In the present invention, the vacuum drying is preferably carried out using a vacuum belt dryer; the vacuum drying time is preferably 2-4h, more preferably 2.5-3.5h, and more preferably 3h; the vacuum drying is preferably dried to a water content of the dragon head fish active peptide of ≦5%; after the vacuum drying, a powdered dragon head fish active peptide is obtained.

[0033] The present invention provides a dragonhead fish active peptide prepared by the preparation method, wherein the mass percentage of polypeptides with a molecular weight less than 1KDa in the dragonhead fish active peptide is 40-60%, preferably 45-55%. In the present invention, the dragonhead fish active peptide has low saltiness and umami induction values, greatly reduced bitterness, good flavor, and strong antioxidant activity.

[0034] The present invention also provides the use of the dragon head fish active peptide in the preparation of antioxidant functional food. The present invention has no special limitation on the type of the antioxidant functional food, and any type of functional food can be used.

[0035] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] Example 1

[0037] Raw material processing: thawing the frozen dragon head fish with running water, removing its head, tail and internal organs after thawing to obtain fish meat;

[0038] Preparation of fish paste: The pretreated fish meat is mixed with water in a mass ratio of 10:7, and then crushed into fish paste using a chopper, and then further sheared and homogenized using a colloid mill to obtain dragon head fish paste;

[0039] Enzymatic hydrolysis: add 1.5% of the mass of fish paste with a mixture of papain and neutral protease, the mass ratio of papain to neutral protease is 1:2, adjust the pH to 7.0, then place in a 55°C water bath, enzymatic hydrolysis for 5.5h, and inactivate the enzyme at 95°C for 15min;

[0040] Centrifugation: Centrifuge the enzymatic hydrolysate at 10000r / min for 10min to remove the precipitate to obtain a relatively clear enzymatic hydrolysate;

[0041] Filter pressing: The relatively clear enzymatic hydrolysate is further filtered through a 1 μm membrane to remove excess impurities and undigested proteins to obtain a stable and uniform clear enzymatic hydrolysate.

[0042] Vacuum concentration: the enzymatic hydrolysate is placed at 45°C and -0.1 MPa pressure for vacuum concentration until the total solid content of the enzymatic hydrolysate is 25%;

[0043] Vacuum drying: The concentrated enzymatic hydrolysate was placed in a vacuum belt dryer and vacuum dried at 90°C and 81.3 KPa for 3 hours until the moisture content of the powder was ≦5% to obtain the dragon head fish active peptide.

[0044] Example 2

[0045] Raw material processing: thawing the frozen dragon head fish with running water, removing its head, tail and internal organs after thawing to obtain fish meat;

[0046] Preparation of fish paste: the pre-treated fish meat is mixed with water in a mass ratio of 9:7, and then crushed into fish paste by a chopper, and then further sheared and homogenized by a colloid mill to obtain dragon head fish paste;

[0047] Enzymatic hydrolysis: add 1.5% of the mass of fish paste with a mixture of papain and neutral protease, the mass ratio of papain to neutral protease is 1:2, adjust the pH to 7.0, then place in a 55°C water bath, enzymatic hydrolysis for 5.5h, and inactivate the enzyme at 95°C for 15min;

[0048] Centrifugation: Centrifuge the enzymatic hydrolysate at 10000r / min for 10min to remove the precipitate to obtain a relatively clear enzymatic hydrolysate;

[0049] Filter pressing: The relatively clear enzymatic hydrolysate is further filtered through a 1 μm membrane to remove excess impurities and undigested proteins to obtain a stable and uniform clear enzymatic hydrolysate.

[0050] Vacuum concentration: the enzymatic hydrolysate is placed at 45°C and -0.1 MPa pressure for vacuum concentration until the total solid content of the enzymatic hydrolysate is 27%;

[0051] Vacuum drying: The concentrated enzymatic hydrolysate was placed in a vacuum belt dryer and vacuum dried at 100°C and 81.3 KPa for 3 hours until the moisture content of the powder was ≦5% to obtain the dragon head fish active peptide.

[0052] Example 3

[0053] Raw material processing: thawing the frozen dragon head fish with running water, removing its head, tail and internal organs after thawing to obtain fish meat;

[0054] Preparation of fish paste: The pretreated fish meat is mixed with water in a mass ratio of 11:7, and then crushed into fish paste by a chopper, and then further sheared and homogenized by a colloid mill to obtain dragon head fish paste;

[0055] Enzymatic hydrolysis: add 1.5% of the mass of fish paste with a mixture of papain and neutral protease, the mass ratio of papain to neutral protease is 1:2, adjust the pH to 7.0, then place in a 55°C water bath, enzymatic hydrolysis for 5.5h, and inactivate the enzyme at 95°C for 15min;

[0056] Centrifugation: Centrifuge the enzymatic hydrolysate at 10000r / min for 10min to remove the precipitate to obtain a relatively clear enzymatic hydrolysate;

[0057] Filter pressing: The relatively clear enzymatic hydrolysate is further filtered through a 1 μm membrane to remove excess impurities and undigested proteins to obtain a stable and uniform clear enzymatic hydrolysate.

[0058] Vacuum concentration: the enzymatic hydrolysate is placed at 45°C and -0.1 MPa pressure for vacuum concentration until the total solid content of the enzymatic hydrolysate is 25%;

[0059] Vacuum drying: The concentrated enzymatic hydrolysate was placed in a vacuum belt dryer and vacuum dried at 110°C and 81.3 KPa for 3 hours until the moisture content of the powder was ≦5% to obtain the dragon head fish active peptide.

[0060] Comparative Example 1:

[0061] A method for preparing dragon fish active peptide by freeze drying, the steps are as follows:

[0062] Raw material processing: thawing the frozen dragon head fish with running water, removing its head, tail and internal organs after thawing to obtain fish meat;

[0063] Preparation of fish paste: The pretreated fish meat is mixed with water in a mass ratio of 10:7, and then crushed into fish paste using a chopper, and then further sheared and homogenized using a colloid mill to obtain dragon head fish paste;

[0064] Add 1.5% of the mass of fish paste of a mixture of papain and neutral protease, the mass ratio of papain to neutral protease is 1:2, adjust the pH to 7.0, then place in a 55°C water bath, enzymolyze for 5.5 hours, and inactivate the enzyme at 95°C for 15 minutes;

[0065] The enzymatic hydrolysate was centrifuged at 10000 r / min for 10 min, and the precipitate was removed to obtain a relatively clear enzymatic hydrolysate;

[0066] The relatively clear enzymatic hydrolysate is further filtered through a 1 μm membrane to remove excess impurities and undigested proteins, thereby obtaining a stable and uniform clear enzymatic hydrolysate.

[0067] The enzymatic hydrolysate was placed in a disposable culture dish and frozen in a -80°C refrigerator for 6 hours, and then the pre-frozen sample was placed in a freeze dryer for freeze drying; the freeze drying process was: primary drying for 12 hours at -40°C and a pressure of 10Pa, and then the temperature was raised to 30°C for drying for 24 hours.

[0068] Comparative Example 2:

[0069] A method for preparing dragon fish active peptide by spray drying, the steps are as follows:

[0070] Raw material processing: thawing the frozen dragon head fish with running water, removing its head, tail and internal organs after thawing to obtain fish meat;

[0071] Preparation of fish paste: The pretreated fish meat is mixed with water in a mass ratio of 10:7, and then crushed into fish paste using a chopper, and then further sheared and homogenized using a colloid mill to obtain dragon head fish paste;

[0072] Add 1.5% of the mass of fish paste of a mixture of papain and neutral protease, the mass ratio of papain to neutral protease is 1:2, adjust the pH to 7.0, then place in a 55°C water bath, enzymolyze for 5.5 hours, and inactivate the enzyme at 95°C for 15 minutes;

[0073] The enzymatic hydrolysate was centrifuged at 10000 r / min for 10 min, and the precipitate was removed to obtain a relatively clear enzymatic hydrolysate;

[0074] The relatively clear enzymatic hydrolysate is further filtered through a 1 μm membrane to remove excess impurities and undigested proteins, thereby obtaining a stable and uniform clear enzymatic hydrolysate.

[0075] The enzymatic hydrolysate was dried using a spray dryer with an inlet temperature of 160°C, an outlet temperature of 100°C, a gas flow rate of 40%, and a pump rate of 20%.

[0076] Experimental example

[0077] The molecular weight distribution of the dragonhead fish polypeptides prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 was measured, the dragonhead fish active peptides were analyzed using an electronic nose and an electronic tongue, and the antioxidant activity was measured.

[0078] 1 Molecular weight distribution determination

[0079] UltraflextremeMALDI-TOF (Bruker, Germany) was used to test the molecular weight distribution. 1 μl of sample and 1 μl of saturated HCCA matrix solution (TA50: acetonitrile / 0.1% TFA = 1:1) were mixed evenly, and 1 μl was spotted on the MALDIGround Steel target plate and dried naturally. The target plate was placed in the MALDI mass spectrometer, and the FlexControl software was opened to measure in the linear positive ion mode (Linearpositive ion mode) LP_0.4-12. Finally, the data was analyzed by the FlexAnalysis software.

[0080] 2. Sensory properties

[0081] Electronic tongue

[0082] The taste test was performed using an electronic tongue taste analysis system (INSENT SA402B; Intelligent Sensor Technology, Japan). Accurately weigh 0.5 g of dry sample powder in a centrifuge tube, add 30 ml of pure water and shake until completely dissolved, transfer to a 100 ml volumetric flask to make up the volume, and the solution after making up the volume is the electronic tongue test solution. The test solution is placed in a special container for the electronic tongue, and the appropriate sensor and test mode are selected. Each sample is measured 4 times, and 3 stable electronic tongue response values ​​are selected for subsequent analysis.

[0083] Electronic nose

[0084] The odor test was performed using an electronic nose detection system. 1.000 g of different dry samples were weighed and placed in a 20 mL headspace bottle with a polytetrafluoroethylene cap, and injected and tested at room temperature. The detection parameters were set as follows: sampling interval 1 s, detection time 80 s, cleaning time 120 s, and injection flow rate 400 ml / min.

[0085] 3 Antioxidant Activity

[0086] DPPH scavenging activity

[0087] Take 1ml sample solution (1mg / mL) and mix it with 1mL DPPH solution (0.1mmol / L) and react in the dark for 30min, then measure the absorbance value Ai at 517nm. Under the same absorbance conditions, use 1mL ethanol and 1mL sample or 1mL DPPH solution to measure Aj and Ao as blank group and control group respectively. The calculation formula is as follows:

[0088] DPPH radical scavenging rate(%)=[1-(A i -A j ) / A0]*100%

[0089] Reduction power

[0090] Take 0.5mL of sample solution (1mg / mL), add 2.5mL of phosphate buffer (0.2mol / L, pH6.6) and 2.5mL of potassium ferricyanide solution (1%, v / v), mix well, and place in a water bath at 50℃ for 20min. Then add 2.5mL of trichloroacetic acid (10%, vv) and react at room temperature for 10min. Finally, take 2.5mL of reaction solution and mix with 0.5mL of ferric chloride solution (0.1%, v) and 2.5mL of distilled water. After reacting for 10min, measure the absorbance at 700nm.

[0091] The molecular weight distribution results are as follows Figure 1 As shown in Table 1, the dragonhead fish polypeptides prepared by different drying processes are mainly composed of peptides with a molecular weight of less than 3KDa, accounting for 98.3%, 97.54% and 98.28% respectively. However, compared with freeze drying and spray drying, the molecular weight of the dragonhead fish polypeptide prepared by vacuum drying in the method provided by the present invention shifts to the range of small molecular weight, among which the proportion of components with a molecular weight of <1KDa increases by 23.04% compared with freeze drying.

[0092] Table 1 Determination results of polypeptide molecular weight distribution obtained from Examples 1 to 3 and Comparative Examples 1 to 2

[0093] Molecular weight range <1KDa 1~3KDa >3KDa Example 1 48.54％ 49.74％ 1.72％ Example 2 47.48％ 48.7％ 3.82％ Example 3 43.06％ 48.52％ 8.42％ Comparative Example 1 25.5％ 72.8％ 1.7％ Comparative Example 2 30.98％ 66.56％ 2.46％

[0094] Sensory characteristics analysis, electronic tongue results such as Figure 2 As shown, compared with freeze drying and spray drying, the sensor sensing value of the salty and umami taste of the dragon head fish polypeptide prepared by the method of the present invention is the lowest, and the bitter taste produced is also greatly reduced, indicating that vacuum drying can improve bad flavors. Electronic nose ( Figure 3 ) The results showed that the dragonhead fish polypeptide prepared by the method of the present invention showed higher sensitivity to sulfides (W1W), aromatic components and organic sulfides (W2W) and nitrogen oxides (W5S). Since these compounds have a low odor threshold, they can significantly contribute to the overall aroma of the final product.

[0095] The results of antioxidant activity (DPPH scavenging activity, reducing power) showed that the antioxidant activity of dragon head fish peptides prepared by vacuum drying was stronger than that of freeze drying and spray drying.

[0096] From the above results, it can be seen that the dragonhead fish polypeptide prepared by the method of the present invention can improve the bad flavor of the dragonhead fish polypeptide itself, the product flavor and sensory evaluation are good, the antioxidant activity is strong, and the peptide composition with a molecular weight of less than 3KDa accounts for more than 98%, and the proportion of components with a molecular weight of less than 1KDa has increased significantly.

Claims

1. A method for preparing a dragon head fish active peptide, characterized in that: The following steps are involved: 1) hydrolyzing the dragon fish paste to obtain a fish paste hydrolyzate; 2) filtering the fish paste enzymatic hydrolysate to obtain a clarified enzymatic hydrolysate; 3) vacuum concentrating the clarified enzymatic hydrolysate to obtain a concentrated solution; 4) vacuum drying the concentrated solution to obtain the dragon fish active peptide; Step 3) The temperature of the vacuum concentration is 40 to 50°C, and the pressure of the vacuum concentration is -0.05 to -0.15Mpa; Step 4) The temperature of the vacuum drying is 80-110° C., and the pressure of the vacuum drying is 80-82 KPa.

2. The preparation method according to claim 1, characterized in that: The vacuum concentration in step 3) is concentrated until the total solid content of the clarified enzymatic hydrolysate is ≥ 25%.

3. The preparation method according to claim 1 or 2, characterized in that: Step 4) The vacuum drying is performed until the water content of the dragon fish active peptide is less than 5%.

4. The preparation method according to claim 1, characterized in that: Step 1) The enzymes used for enzymolysis are papain and neutral protease; the mass ratio of the papain and neutral protease is 1:(1.5-2.5); the total mass of the papain and neutral protease is 1-2% of the mass of the dragonhead fish paste.

5. The preparation method according to claim 1 or 4, characterized in that: The temperature of the enzymolysis is 50-60° C., and the time of the enzymolysis is 5-6 hours.

6. The preparation method according to claim 5, characterized in that: After the enzymatic hydrolysis, the enzyme is inactivated and centrifuged to obtain the fish paste enzymatic hydrolysate; the centrifugal speed is 8000-12000 rpm, and the centrifugal time is 8-12 minutes.

7. The preparation method according to claim 1, characterized in that: Step 2) The filtration is pressure filtration, and the pore size of the filter membrane of the pressure filtration is 1 to 2 μm.

8. The preparation method according to claim 1, characterized in that: The dragon head fish paste in step 1) is obtained by mixing the dragon head fish with water, crushing it, and passing it through a colloid mill.

9. The active peptide of dragon head fish obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The mass percentage of the polypeptide with a molecular weight less than 1KDa in the dragonhead fish active peptide is 40-60%.

10. Use of the active peptide from dragon fish according to claim 9 in the preparation of antioxidant functional foods.

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