Locust umami peptide as well as preparation method and application thereof

Abstract

The invention discloses grasshopper umami peptide and a preparation method and application thereof. The amino acid sequences of the grasshopper umami peptide are NGWGDY, NVTY, VVNY, NGSGL and GDRFL. The preparation method I comprises the following steps: (1) sequentially carrying out swelling, washing, Fmoc protecting group removal and condensation reaction on dichloro resin; and (2) cutting and purifying. A second preparation method comprises the following steps: (1) cleaning, blanching, air-drying, crushing, sieving and degreasing the locusts in sequence; (2) dissolving in water, adjusting the pH value of the solution, adding Alcalase, carrying out enzymolysis, enzyme deactivation and centrifugation, taking supernate, and carrying out freeze drying; (3) dissolving in water, performing ultrafiltration separation, collecting permeate, and concentrating; and (4) dissolving in water, carrying out gel chromatography separation, collecting, and freeze-drying to obtain the product. The grasshopper umami peptide contains umami active fragments, has umami characteristics, has an umami threshold value lower than that of sodium glutamate, can enhance umami of simulated broth to a certain extent, has potential umami presenting / umami increasing effects, can be used for umami increasing seasonings, and can also be compounded with other umami products for use.

Description

Technical Field

[0001] The present invention relates to the technical field of flavor peptides, and more specifically, to a locust umami peptide, a preparation method thereof, and an application thereof. Background Art

[0002] Umami is a taste that gives people a sense of pleasure and is also one of the dimensions for people to judge the deliciousness of food. Since Professor Kikunae Ikeda first proposed the concept of umami in 1908, people have never stopped researching umami. There are a wide variety of umami components, including organic acids, organic bases, free amino acids and their salts, as well as small molecular peptides, and each component exhibits different levels of umami characteristics.

[0003] Umami peptides refer to small molecular peptides that have umami taste at a certain concentration, and are widely distributed in meats, fish and shellfish, beans and some fermented foods. Umami peptides have multiple functional characteristics, such as conferring / enhancing the umami of food, reducing the dependence of food on salt, and providing nutrition and other benefits, and have great market potential in the condiment field.

[0004] In recent years, researchers at home and abroad have isolated a large number of umami peptides from food-derived animal protein hydrolysates. Liu Tianhong et al. used flavor protease and animal protease to hydrolyze nereis, and obtained nereis polypeptides with obvious umami. Ding Yuwen et al. used flavor protease to prepare silkworm pupa protein hydrolysate, and successfully isolated 6 umami peptides Gly-Val, Gly-Tyr, Ala-Leu, Asp-Phe, Leu-Pro and Gly-Leu from the silkworm pupa protein hydrolysate. Zhang Zhe et al. adopted a method of complex enzymatic hydrolysis of tuna fish meat protein with flavor protease and papain, and finally isolated and identified 14 umami peptides with obvious umami, and the umami thresholds were between 0.12 - 0.30 mg / mL, all lower than the umami threshold of sodium glutamate (0.30 mg / mL). Chinese invention patent CN202410881140.8 discloses an umami peptide of Portunus trituberculatus and its application, and this umami peptide can be used as an umami agent and can also be used as a basic raw material for a novel natural compound condiment. Chinese invention patent CN202410127227.6 discloses two umami peptides (DEEYPDL and DGEKVDFDD), and the umami thresholds are between 0.18 - 0.34 mg / mL, and they can be used as new umami peptide raw materials for the development of condiments.

[0005] In China, locust resources are abundant. Since the Han Dynasty, there has been a habit of eating locusts, and there is even a tradition of drying them, grinding them into powder, and using them to replace monosodium glutamate for seasoning. The protein content of locusts accounts for 66.37% - 85.67% of the dry matter weight. Its protein contains 18 kinds of amino acids, and the content of umami amino acids accounts for 30% - 40% of the total amino acids, having relatively high umami potential.

[0006] However, the current development and utilization of locusts mainly focus on insect feed, with less involvement in the field of food processing. There are few reports on the extraction, separation, and flavor characteristics of locust umami peptides.

[0007] Therefore, how to find an efficient method for separating and preparing locust umami peptides, explore their umami characteristics and umami mechanisms, and develop new umami seasonings is the current research focus. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a locust umami peptide, its preparation method and application to solve the deficiencies in the prior art.

[0009] To achieve the above purpose, the present invention adopts the following technical solutions:

[0010] A locust umami peptide with the amino acid sequences NGWGDY (Asn - Gly - Trp - Gly - Asp - Tyr), NVTY (Asn - Val - Thr - Tyr), VVNY (Val - Val - Asn - Tyr), NGSGL (Asn - Gly - Ser - Gly - Leu), and GDRFL (Gly - Asp - Arg - Phe - Leu).

[0011] A preparation method (solid - phase synthesis method) of the above - mentioned locust umami peptide, specifically including the following steps:

[0012] (1) First, the dichloride resin is successively swollen, washed, and the Fmoc protecting group is removed. Then, according to the amino acid sequence of Asn - Gly - Trp - Gly - Asp - Tyr, Asn - Val - Thr - Tyr, Val - Val - Asn - Tyr, Asn - Gly - Ser - Gly - Leu, and Gly - Asp - Arg - Phe - Leu, amino acids are respectively added for condensation reaction, and the process of deprotection - protection - condensation is repeated until all amino acids are connected.

[0013] (2) First, the dichloride resin is cleaved to obtain crude peptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL respectively. Then, reverse - phase high - performance liquid chromatography is used for purification to obtain pure peptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL respectively, which are the locust umami peptides.

[0014] Furthermore, in the above step (1), the mass ratio of the dichloride resin to the amino acid is 1:8.

[0015] A preparation method (separation and purification method) of the above - mentioned locust umami peptide, specifically including the following steps:

[0016] (1) Wash the locusts successively, blanch them, air-dry them, crush them, sieve them, and degrease them to obtain locust protein powder;

[0017] (2) Dissolve the locust protein powder in water, adjust the pH value of the solution, add Alcalase enzyme, carry out enzymatic hydrolysis, inactivate the enzyme, centrifuge, take the supernatant, and freeze-dry it to obtain locust protein hydrolysate;

[0018] (3) Dissolve the locust protein hydrolysate in water, carry out ultrafiltration separation, collect the permeate, and concentrate it to obtain locust ultrafiltration concentrate;

[0019] (4) Dissolve the locust ultrafiltration concentrate in water, carry out gel chromatography separation, collect and combine multiple elution peak components, select the components of the polypeptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL with the strongest umami taste for collection, and freeze-dry them to obtain locust umami peptides.

[0020] Furthermore, in the above step (1), the blanching time is 3 - 5 min; the air-drying is carried out by drying in the natural environment; the mesh number of the sieve for sieving is 40 meshes.

[0021] Furthermore, in the above step (2), the dosage ratio of the locust protein powder to water is (6 - 7) g : (60 - 105) mL; the pH value of the solution is adjusted to 8; the enzyme activity of Alcalase enzyme is 10000 u / g, and the addition amount is 1% - 5% of the mass of the locust protein powder; the temperature of enzymatic hydrolysis is 50 - 55 °C, and the time is 3 - 4 h; the temperature of inactivating the enzyme is 100 °C, and the time is 10 min; the temperature of centrifugation is 4 °C, the rotation speed is 8000 rpm, and the time is 15 min.

[0022] Furthermore, in the above step (3), the dosage ratio of the locust protein hydrolysate to water is 2 g : 500 mL; the ultrafiltration separation uses 10 kDa and 3 kDa filter membrane packages, and the temperature is 4 °C.

[0023] Furthermore, in the above step (4), the dosage ratio of the locust ultrafiltration concentrate to water is 4 mg : 1 mL; the equipment for gel chromatography separation is a Sephadex G-25 gel column, the sample loading amount is 1 mL, it is eluted with deionized water at a flow rate of 1 mL / min, and the detection wavelength is 220 nm.

[0024] The present invention also claims the application of the above locust umami peptides or the locust umami peptides prepared by the above preparation method in the preparation of flavor-enhancing seasonings.

[0025] Through the above technical solutions, compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The structure of the locust umami peptide of the present invention is clear and can be prepared by solid-phase chemical synthesis or obtained by separating and purifying locust protease hydrolysate.

[0027] 2. NGWGDY, NVTY, VVNY, NGSGL, and GDRFL in the locust umami peptide of the present invention all have obvious umami, with weak bitterness and sourness. The umami thresholds are 0.14, 0.20, 0.25, 0.12, and 0.08 mg / mL respectively, all lower than the umami threshold of sodium glutamate, which is 0.30 mg / mL.

[0028] 3. The locust umami peptide of the present invention has a good umami-enhancing effect on the simulated broth. After adding NGWGDY, NVTY, VVNY, NGSGL, and GDRFL respectively, the umami of the simulated broth is increased by 50.0%, 70.0%, 56.0%, 64.0%, and 62% respectively.

[0029] 4. The locust umami peptide of the present invention contains umami-active fragments, has umami characteristics, and its umami threshold is lower than that of sodium glutamate. At the same time, it can enhance the umami of the simulated broth to a certain extent, has potential umami-presenting / umami-enhancing effects, can be used in umami condiments, and can also be used in compound with other umami products.

[0030] Among them, the umami-active fragment refers to specific amino acid monomers and corresponding amino acid sequences that play a key role in presenting umami in the locust umami peptide.

[0031] The umami characteristics refer to that the locust umami peptide has a taste similar to that of sodium glutamate, which is determined by sensory evaluation and electronic tongue measurement, can give the food a strong umami sensory experience, and enhance the overall umami of the food.

[0032] The umami threshold refers to the lowest concentration at which umami can be distinguished.

[0033] The umami-enhancing effect refers to that the locust umami peptide can enhance the umami of the simulated broth and make the taste of the broth more intense.

[0034] The simulated broth refers to a liquid prepared by artificially compounding 2 mg / mL monosodium glutamate and 2 mg / mL NaCl, which is used to simulate the taste and flavor of the broth. Description of the Drawings

[0035] Figure 1 It is the umami graph of the locust umami peptide in Examples 1-2 and the comparative example;

[0036] Figure 2 It is the elution curve of Sephadex G-25 gel column filtration chromatography in Example 2;

[0037] Figure 3 It is the sensory radar graph of the locust umami peptide in Example 2;

[0038] Figure 4 Electronic tongue graph of locust umami peptide in Example 2;

[0039] Figure 5 Umami enhancement graph of locust umami peptide in Example 2. Specific implementation manners

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] Example 1

[0042] Preparation method of locust umami peptide, specifically including the following steps:

[0043] (1) First, 1 g of dichloro resin is successively swollen, washed, and deprotected from the Fmoc group, and then amino acids are added for condensation reaction in the amino acid sequences of Asn-Gly-Trp-Gly-Asp-Tyr, Asn-Val-Thr-Tyr, Val-Val-Asn-Tyr, Asn-Gly-Ser-Gly-Leu, and Gly-Asp-Arg-Phe-Leu. The mass ratio of dichloro resin to amino acid is 1:8, and the process of deprotection-protection-condensation is repeated until all amino acids are connected;

[0044] (2) First, the dichloro resin is cleaved to obtain crude polypeptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL, and then purified by reverse-phase high-performance liquid chromatography to obtain pure polypeptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL (>95%), which are locust umami peptides.

[0045] Example 2

[0046] Preparation method of locust umami peptide, specifically including the following steps:

[0047] (1) The locusts are successively washed, blanched for 3 min, placed in a natural environment to dry in the air, crushed, sieved through a 40-mesh sieve, and defatted to obtain locust protein powder;

[0048] (2) Dissolve 6 g of locust protein powder in 72 mL of deionized water, adjust the pH value of the solution to 8, add 0.3 g of Alcalase enzyme with an enzyme activity of 10000 u / g, place it in a water bath shaker at 55 °C for enzymatic hydrolysis for 3 h. After the reaction, inactivate the enzyme in boiling water at 100 °C for 10 min, centrifuge at 4 °C and 8000 rpm for 15 min, take the supernatant, and freeze-dry to obtain locust protein hydrolysate;

[0049] (3) Dissolve 2 g of locust protein hydrolysate in 500 mL of deionized water, and perform ultrafiltration separation at 4 °C using 10 kDa and 3 kDa membrane packages. Pass through the 10 kDa and 3 kDa ultrafiltration membranes in sequence, collect the permeate, and concentrate to obtain locust ultrafiltration concentrate with a molecular weight below 3 kDa;

[0050] (4) Dissolve 4 mg of locust ultrafiltration concentrate in 1 mL of deionized water, separate and purify it through Sephadex G-25 gel. The sample loading volume is 1 mL, elute with deionized water at a flow rate of 1 mL / min, the detection wavelength is 220 nm, collect and combine into multiple elution peak components, and select the components of polypeptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL with the strongest umami taste for collection, and freeze-dry to obtain locust umami peptide.

[0051] Example 3

[0052] A method for preparing locust umami peptide, specifically including the following steps:

[0053] (1) Wash the locusts in sequence, blanch them for 5 min, place them in a natural environment to dry in the sun, crush them, pass through a 40-mesh sieve, and defat them to obtain locust protein powder;

[0054] (2) Dissolve 6 g of locust protein powder in 72 mL of deionized water, adjust the pH value of the solution to 8, add 0.06 g of Alcalase enzyme with an enzyme activity of 10000 u / g, place it in a water bath shaker at 55 °C for enzymatic hydrolysis for 3 h. After the reaction, inactivate the enzyme in boiling water at 100 °C for 10 min, centrifuge at 4 °C and 8000 rpm for 15 min, take the supernatant, and freeze-dry to obtain locust protein hydrolysate;

[0055] (3) Dissolve 2 g of locust protein hydrolysate in 500 mL of deionized water, and perform ultrafiltration separation at 4 °C using 10 kDa and 3 kDa membrane packages. Pass through the 10 kDa and 3 kDa ultrafiltration membranes in sequence, collect the permeate, and concentrate to obtain locust ultrafiltration concentrate with a molecular weight below 3 kDa;

[0056] (4) Dissolve 4 mg of locust ultrafiltration concentrate in 1 mL of deionized water, separate and purify it through Sephadex G-25 gel. The sample loading volume is 1 mL, elute with deionized water at a flow rate of 1 mL / min, the detection wavelength is 220 nm, collect and combine multiple elution peak components, select the components of polypeptides NGWGDY, NVTY, VVNY, NGSGL and GDRFL with the strongest umami taste for collection, and freeze-dry to obtain locust umami peptides.

[0057] Control example

[0058] A preparation method of locust umami peptides specifically includes the following steps:

[0059] (1) Wash the locusts in sequence, blanch for 3 min, place them in a natural environment to dry in the sun, crush them, pass through a 40-mesh sieve, and degrease to obtain locust protein powder;

[0060] (2) Dissolve 6 g of locust protein powder in 72 mL of deionized water, adjust the pH value of the solution to 7, add 0.3 g of flavor protease with an enzyme activity of 20 u / g, place it in a water bath shaker at 50 °C for enzymatic hydrolysis for 3 h, after the reaction, inactivate the enzyme in boiling water at 100 °C for 10 min, centrifuge at 4 °C and 8000 rpm for 15 min, take the supernatant, and freeze-dry to obtain locust protease hydrolysate;

[0061] (3) Dissolve 2 g of locust protease hydrolysate in 500 mL of deionized water, perform ultrafiltration separation at 4 °C using 10 kDa and 3 kDa filter membrane packages, pass through 10 kDa and 3 kDa ultrafiltration membranes in sequence, collect the permeate, and concentrate to obtain locust ultrafiltration concentrate with a molecular weight below 3 kDa;

[0062] (4) Dissolve 4 mg of locust ultrafiltration concentrate in 1 mL of deionized water, separate and purify it through Sephadex G-25 gel. The sample loading volume is 1 mL, elute with deionized water at a flow rate of 1 mL / min, the detection wavelength is 220 nm, collect and combine multiple elution peak components, select the components with the strongest umami taste for collection, and freeze-dry to obtain locust umami peptides.

[0063] Performance test

[0064] 1. Sensory evaluation of locust umami peptides

[0065] The grasshopper umami peptide was formulated into a solution sample with a concentration of 1 mg / mL. Ten sensory panelists (5 males and 5 females, aged 20 - 25 years) who had received sensory training tasted the sample, described the taste characteristics of the sample, and scored it with reference to the taste standard samples. All evaluations were conducted in a sensory evaluation room at 24°C. The NaCl solution (0.35%, w / v) was salty, the citric acid solution (0.08%, w / v) was sour, the monosodium glutamate solution (0.35%, w / v) was umami, the sucrose solution (1.00%, w / v) was sweet, and the L-leucine solution (0.25%, w / v) was bitter. The sensory evaluation score of the sample was from 0 to 10 points, with 0 points indicating no taste and 10 points indicating a more prominent taste. The taste score of the reference standard solution was 5 points. The panelists sipped the sample successively, held it in the mouth for 10 s and then spat it out. After the evaluation, they rinsed their mouths with pure water.

[0066] 2. Determination of the sensory threshold of grasshopper umami peptide

[0067] Using the triangle test method, the initial concentration of grasshopper umami peptide in deionized water was 1 mg / mL. The sample was serially diluted 1:1 by equal volume with pure water, and the diluted samples were coded according to increasing concentration and submitted to the sensory panel members for tasting. The panel members were required to distinguish the sample containing grasshopper umami peptide from two cups of pure water and one cup of grasshopper umami peptide sample. Record the concentration corresponding to the ability to clearly distinguish the sample from the blank control (pure water) group, and take this concentration as its corresponding threshold. The umami threshold is the average value of individual thresholds.

[0068] 3. Electronic tongue analysis of grasshopper umami peptide

[0069] The electronic tongue is equipped with 9 independent taste sensors, mainly composed of a series of interactive sensitive sensors, signal acquisition circuits and data processing methods based on pattern recognition, for qualitative and quantitative analysis and detection of the taste characteristics of samples. By analyzing the basic components that cause different tastes in grasshopper umami peptide, standard gradient solutions of five basic tastes were prepared, and standard models of sour, sweet, bitter, salty and umami were established. Then, the taste characteristics of grasshopper umami peptide were measured and compared to predict whether they have fresh taste characteristics. The sensor and the reference probe were inserted into the sample solution, and the relevant flavor values were responded by detecting the change of membrane potential.

[0070] 4. Umami enhancement analysis of grasshopper umami peptide

[0071] The grasshopper umami peptide was formulated into a solution with a concentration of 5 mg / mL respectively, and after being filtered through a 0.22 μm water membrane, it was added to the simulated broth (2 mg / mL monosodium glutamate and 2 mg / mL NaCl). The score of the control simulated broth model was 5 points. The umami of the composite aqueous solution of a single umami peptide and the simulated broth was scored, and the scoring range was from 0 to 10 points, with 0 points indicating almost no taste and 10 points indicating a more prominent taste.

[0072] The results are shown in Table 1 and Figures 1-5 as follows.

[0073] Table 1 Sensory analysis of locust umami peptides prepared in Examples 2-3 and Comparative Examples

[0074]

[0075]

[0076] As can be seen from Table 1 and Figure 1 it can be seen that compared with the locust umami peptide in Example 3, the locust umami peptide in Example 2 has stronger umami, no strong bitterness, and better umami scores and umami thresholds. Compared with the locust umami peptides in Example 2 and Example 3, under the condition of not changing other experimental conditions, the locust umami peptide prepared by enzymatically hydrolyzing locust protein with flavor protease in the comparative example has stronger sourness, slight bitterness and accompanied by astringency, and the umami scores and umami thresholds are not ideal. Therefore, Example 2 is the best example.

[0077] In Example 2, after enzymatically hydrolyzing locusts with 5% Alcalase enzyme, ultrafiltration separation was carried out at 4 °C using 10 kDa and 3 kDa filter membranes to obtain the U1 fraction with a molecular weight <3 kDa, the U2 fraction with a molecular weight of 3-10 kDa, and the U3 fraction with a molecular weight >10 kDa. The umami evaluation of U1, U2, and U3 was carried out by the sensory evaluation method, among which the umami of U1 was the most obvious, and U2 and U3 decreased in turn. Subsequently, the U1 fraction with the strongest umami was separated and purified by a Sephadex G-25 gel column, and four elution peak fractions F1, F2, F3, and F4 were collected ( Figure 2 ).

[0078] The sensory evaluation results showed that the F3 fraction had the strongest umami. Therefore, the F3 fraction was selected for mass spectrometry analysis to obtain the amino acid sequence of the locust umami peptide. The mass spectrometry analysis data was automatically analyzed using Peaks Studio 8.0 software. The amino acid sequence of the peptide was re-ordered from the N-terminus to the C-terminus, and the peptide segments with a confidence level (ALC) greater than 80% were selected for analysis. BIOPEP-UWM was used to predict and identify the umami active fragments in the peptide segments, and the peptide segments with a umami amino acid fragment frequency >0.50 were selected, which were the locust umami peptides in Example 2.

[0079] Further sensory evaluation and electronic tongue measurement results showed that the locust umami peptide in Example 2 had obvious umami, and its umami thresholds were 0.14, 0.20, 0.25, 0.12, and 0.08 mg / mL ( Figures 3-4 ), respectively, all significantly lower than the umami threshold of monosodium glutamate, 0.30 mg / mL.

[0080] The results of the umami enhancement test showed that after adding the locust umami peptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL of Example 2, the umami of the simulated broth increased by 50.0%, 70.0%, 56.0%, 64.0%, and 62% respectively ( Figure 5 ), indicating that the locust umami peptides of the present invention have strong umami-presenting and umami-enhancing properties and can be used to prepare novel umami seasonings.

[0081] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A grasshopper umami peptide, characterized in that, The amino acid sequences are NGWGDY, NVTY, VVNY, NGSGL, and GDRFL.

2. A method for preparing the locust umami peptide as described in claim 1, characterized in that, Specifically, it includes the following steps: (1) First, the dichloride resin is successively swollen, washed, and the Fmoc protecting group is removed. Then, according to the amino acid sequences of Asn-Gly-Trp-Gly-Asp-Tyr, Asn-Val-Thr-Tyr, Val-Val-Asn-Tyr, Asn-Gly-Ser-Gly-Leu, and Gly-Asp-Arg-Phe-Leu, amino acids are respectively added for condensation reactions. The process of deprotection-condensation is repeated until all amino acids are connected; (2) First, the dichloride resin is cleaved to obtain crude polypeptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL respectively. Then, reverse-phase high-performance liquid chromatography is used for purification to obtain pure polypeptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL respectively, which are the locust umami peptides.

3. The preparation method of a locust umami peptide according to claim 2, characterized in that, In step (1), the mass ratio of the dichloride resin to the amino acid is 1:

8.

4. A preparation method of the locust umami peptide as described in claim 1, characterized in that, Specifically, it includes the following steps: (1) The locusts are successively washed, blanched, air-dried, crushed, sieved, and defatted to obtain locust protein powder; (2) The locust protein powder is dissolved in water, the pH value of the solution is adjusted, Alcalase enzyme is added, enzymatic hydrolysis is carried out, the enzyme is inactivated, centrifuged, the supernatant is taken, and freeze-dried to obtain locust protein hydrolysate; (3) The locust protein hydrolysate is dissolved in water, ultrafiltration separation is carried out, the permeate is collected and concentrated to obtain locust ultrafiltration concentrate; (4) The locust ultrafiltration concentrate is dissolved in water, gel chromatography separation is carried out, the elution peak components are collected and combined into multiple ones, and the components of polypeptides NGWGDY, NVTY, VVNY, NGSGL, and GDRFL with the strongest umami taste are selected for collection and freeze-dried to obtain the locust umami peptides.

5. The preparation method of a locust umami peptide according to claim 4, characterized in that, In step (1), the blanching time is 3 - 5 min; the air-drying is to place it in a natural environment for sun-drying; the mesh number of the sieve for sieving is 40 mesh.

6. The preparation method of a locust umami peptide according to claim 4, characterized in that, In step (2), the dosage ratio of the locust protein powder to water is (6 - 7) g:(60 - 105) mL.

7. The preparation method of a locust umami peptide according to claim 4, characterized in that, In step (2), the pH value of the solution is adjusted to 8; the enzyme activity of the Alcalase enzyme is 10000 u / g, and the addition amount is 1% - 5% of the mass of the locust protein powder; the temperature of the enzymatic hydrolysis is 50 - 55 °C, and the time is 3 - 4 h; the temperature of the enzyme inactivation is 100 °C, and the time is 10 min; the temperature of the centrifugation is 4 °C, the rotation speed is 8000 rpm, and the time is 15 min.

8. The preparation method of a locust umami peptide according to claim 4, characterized in that, In step (3), the dosage ratio of the locust protein hydrolysate to water is 2 g:500 mL; the ultrafiltration separation uses 10 kDa and 3 kDa filter membrane packages, and the temperature is 4 °C.

9. A method for preparing a locust umami peptide according to claim 4, characterized in that, In step (4), the dosage ratio of the locust ultrafiltration concentrate to water is 4 mg:1 mL; the equipment for the gel chromatography separation is a Sephadex G-25 gel column, the sample loading amount is 1 mL, deionized water is used for elution at a flow rate of 1 mL / min, and the detection wavelength is 220 nm.

10. Use of the locust umami peptide as described in claim 1 or the locust umami peptide prepared by the preparation method as described in any one of claims 2-9 in the preparation of a flavor-enhancing condiment.

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