Aquatic product preservative for relieving quality decline of aquatic products and use method of aquatic product preservative

Abstract

The invention provides an aquatic product preservative for relieving quality reduction of aquatic products and a use method of the aquatic product preservative, and relates to the technical field of storage and preservation of the aquatic products. Long-term research finds that the honeysuckle flower extract can be used as a natural aquatic product preservative to relieve quality decline of aquatic products. Specifically, the honeysuckle flower extract is obtained through experimental research by taking penaeus vannamei as an example, and the honeysuckle flower extract can effectively relieve blackening of the head, the tail and the shell of a penaeus vannamei body when the penaeus vannamei body is stored; the problem that the total number of microbial colonies, total volatile basic nitrogen and thiobarbituric acid value in shrimp meat are increased along with the prolonging of the storage time of the penaeus vannamei is solved, and an excellent fresh-keeping effect is shown. And a new strategy is provided for preservation of crustacean aquatic products such as penaeus vannamei boone.

Description

Technical Field

[0001] The invention relates to the technical field of aquatic product storage and preservation, and in particular to an aquatic product preservative for alleviating the decline in the quality of aquatic products and a use method thereof. Background Art

[0002] Shrimp and crab aquatic products (such as white shrimp and crabs) are deeply loved by consumers all over the world because of their delicious taste, high protein content and rich nutrition. However, at the species level, shrimp and crab aquatic products contain a large amount of protein, water and active endogenous enzymes, so they are very easy to deteriorate during storage. In addition, the phenolic compounds in shrimp and crab aquatic products will be oxidized into quinone compounds under the catalysis of polyphenol oxidase (PPO), and the quinone compounds will further polymerize with proteins, amino acids and quinone compounds to form dark brown substances, which will cause shrimp and crab aquatic products to turn black, greatly reducing their sensory quality and economic value, and weakening consumers' desire to buy.

[0003] In order to solve the problem of blackening of shrimp and crab aquatic products, people have adopted various methods and technologies. These methods mainly focus on controlling the key components of catalytic oxidation reactions, such as controlling enzyme activity and reducing oxygen content. Sulfite is currently a commercial preservative that slows down the blackening rate of shrimp and other crustacean aquatic products. With consumers' increasing attention to food safety, especially the awareness and understanding of the side effects of sulfite additives, food safety regulatory agencies have been forced to strictly restrict the use of sulfites in food. In some countries and regions, the use of sulfate compounds for the preservation of shrimp and other aquatic products has even been banned. Because foods with added sulfates will have some sulfates left, the residual sulfates will produce SO2 during human metabolism, which can induce allergic reactions in asthma patients, and in severe cases, it can cause death and threaten human health. Therefore, people have gradually begun to seek safer and more efficient inhibitor alternatives.

[0004] In recent years, 4-hexylresorcinol (4-HR), a derivative of resorcinol, has been used as a safe polyphenol substitute for sulfites. 4-HR specifically binds to PPO, thereby inhibiting the activity of enzymes, thereby inhibiting the blackening of shrimp and crab aquatic products. Although 4-HR does not cause obvious harm to human health, it is expensive and increases production costs. As consumers pay more attention to food safety, the conditions for selecting food additives are becoming more and more stringent, and it is necessary to find more natural additives to replace chemical preservatives.

[0005] Therefore, it is necessary and urgent to research and develop a healthy, safe and efficient aquatic preservative to inhibit the blackening and quality degradation of shrimp and crab aquatic products.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The object of the present invention is to provide an aquatic product preservative for alleviating the deterioration of aquatic product quality and a method of using the same.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] The present invention provides an aquatic product preservative for alleviating the decline in the quality of aquatic products. The aquatic product preservative comprises a honeysuckle extract and an auxiliary material acceptable to the preservative.

[0010] Furthermore, the honeysuckle extract is honeysuckle water-extracted powder;

[0011] Preferably, in the honeysuckle water extract powder, calculated by percentage of components, the content of phenolic acid compounds is ≥18.2%, the content of flavonols and flavonoids is ≥29.0%, the content of cinnamic acid and its derivatives is ≥0.5%, the content of organic acids and their derivatives is ≥10.4%, and the content of benzoic acid and its derivatives is ≥0.4%.

[0012] Furthermore, the aquatic product preservative can be applied to aquatic products such as crustaceans, preferably any one of shrimps or crabs.

[0013] The present invention provides a method for using the above-mentioned aquatic product preservative for alleviating the decline in the quality of aquatic products, and the method comprises:

[0014] The aquatic preservative for alleviating the quality decline of aquatic products is dissolved in a solvent to prepare a preservative aqueous solution; then the aquatic product is immersed in the preservative aqueous solution for immersion treatment, and then drained to obtain the treated aquatic product.

[0015] Furthermore, the concentration of the honeysuckle extract in the aqueous preservative solution is 12-20 mg / mL.

[0016] Furthermore, the solvent is water.

[0017] Furthermore, the temperature for immersing the aquatic product in the preservative aqueous solution for treatment is 4-25°C.

[0018] Furthermore, the time for immersing the aquatic product in the aqueous solution of the preservative for treatment is 10 to 20 minutes.

[0019] Furthermore, the mass volume ratio of the aquatic product to the preservative aqueous solution is 1:1 to 1:5 (w / v).

[0020] Furthermore, the method of use includes:

[0021] S1: dissolving an aquatic product preservative that can alleviate the decline in the quality of aquatic products in a solvent to prepare a preservative aqueous solution;

[0022] The concentration of the honeysuckle extract in the aqueous preservative solution is 12 to 20 mg / mL;

[0023] S2: Immersing the aquatic product in the aqueous solution of the preservative at a mass volume ratio of 1:1 to 1:5, immersing at 4 to 25° C. for 10 to 20 minutes, and then draining to obtain the treated aquatic product.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] After long-term research, the present invention has found that honeysuckle extract can be used as a natural aquatic preservative to alleviate the quality decline of aquatic products. Taking white shrimp as an example, the present invention has found through experimental research that honeysuckle extract effectively alleviates the blackening of the head, tail and shell of white shrimp; as well as the increase in the total number of microbial colonies, total volatile basic nitrogen and thiobarbituric acid value in the shrimp meat with the extension of storage time, showing an excellent preservation effect. It provides a new strategy for the preservation of crustacean aquatic products such as white shrimp. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 The PPO inhibitory activity diagram of honeysuckle extracts of different concentrations provided in Example 2 of the present invention;

[0028] Figure 2 The copper chelating activity diagram of honeysuckle extracts of different concentrations provided in Example 2 of the present invention;

[0029] Figure 3 The photos of the whiteleg shrimps treated by the test groups 1 to 3 provided in Example 3 of the present invention during refrigeration;

[0030] Figure 4 This is a quantitative image analysis diagram of the degree of blackening of samples in test groups 1 to 3 during storage provided in Example 3 of the present invention;

[0031] Figure 5 A quantitative image analysis diagram of the total bacterial count of the samples of test groups 1 to 3 during storage provided in Example 3 of the present invention;

[0032] Figure 6A quantitative image analysis diagram of total volatile basic nitrogen of samples of test groups 1 to 3 during storage provided in Example 3 of the present invention;

[0033] Figure 7 A quantitative image analysis diagram of thiobarbituric acid values ​​of samples of test groups 1 to 3 during storage provided in Example 3 of the present invention;

[0034] Figure 8 A correlation analysis diagram of the freshness index in different treatments of test groups 1 to 3 provided in Example 4 of the present invention;

[0035] Fig. 9 This is a principal component analysis diagram of the freshness index in different treatments of test groups 1 to 3 provided in Example 4 of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the implementation cases in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] According to one aspect of the present invention, an aquatic product preservative for alleviating the degradation of aquatic product quality comprises a honeysuckle extract and an auxiliary material acceptable as a preservative.

[0038] After long-term research, the present invention has found that honeysuckle extract can be used as a natural aquatic preservative to alleviate the quality decline of aquatic products. Taking white shrimp as an example, the present invention has found through experimental research that honeysuckle extract effectively alleviates the blackening of the head, tail and shell of white shrimp; as well as the increase in the total number of microbial colonies, total volatile basic nitrogen and thiobarbituric acid value in the shrimp meat with the extension of storage time, showing an excellent preservation effect. It provides a new strategy for the preservation of crustacean aquatic products such as white shrimp.

[0039] In a preferred embodiment of the present invention, the honeysuckle extract is honeysuckle water-extracted powder;

[0040] Preferably, in the honeysuckle water extract powder, calculated by percentage of components, the content of phenolic acid compounds is ≥18.2%, the content of flavonols and flavonoids is ≥29.0%, the content of cinnamic acid and its derivatives is ≥0.5%, the content of organic acids and their derivatives is ≥10.4%, and the content of benzoic acid and its derivatives is ≥0.4%.

[0041] As a preferred embodiment, the present invention has no particular limitation on the source of the honeysuckle water-extracted powder, and the honeysuckle water-extracted powder may contain the following components in percentage:

[0042] That is, calculated by percentage of components, the content of phenolic acid compounds in the honeysuckle water extract powder is ≥18.2%, the content of flavonols and flavonoids is ≥29.0%, the content of cinnamic acid and its derivatives is ≥0.5%, the content of organic acids and their derivatives is ≥10.4%, and the content of benzoic acid and its derivatives is ≥0.4%.

[0043] The specific source of the honeysuckle water-extracted powder can be prepared by a water-extract preparation method well known to those skilled in the art or purchased from outside; for example, commercial products can be used, or the powder can be prepared by itself using a preparation method well known to those skilled in the art.

[0044] Preferably, the honeysuckle water-extracted powder is a honeysuckle extract (water-extracted yellow-brown powder) produced by Xi'an Baitai Biotechnology Co., Ltd., and the concentration ratio of the honeysuckle water-extracted powder is 10:1, that is, 1 kg of dry powder is extracted from 10 kg of honeysuckle.

[0045] In a preferred embodiment of the present invention, the aquatic product preservative can be applied to aquatic products such as crustaceans, preferably any one of shrimps or crabs.

[0046] According to another aspect of the present invention, a method for using the above-mentioned aquatic product preservative to alleviate the decline in quality of aquatic products comprises:

[0047] The aquatic preservative for alleviating the quality decline of aquatic products is dissolved in a solvent to prepare a preservative aqueous solution; then the aquatic product is immersed in the preservative aqueous solution for immersion treatment, and then drained to obtain the treated aquatic product.

[0048] In a preferred embodiment of the present invention, the concentration of the honeysuckle extract in the aqueous preservative solution is 12-20 mg / mL.

[0049] In a preferred embodiment of the present invention, the solvent is water.

[0050] In a preferred embodiment of the present invention, the temperature for immersing the aquatic product in the aqueous solution of the preservative for treatment is 4-25°C.

[0051] In a preferred embodiment of the present invention, the time for immersing the aquatic product in the aqueous solution of the preservative for treatment is 10 to 20 minutes.

[0052] In a preferred embodiment of the present invention, the mass volume ratio of the aquatic product to the aqueous preservative solution is 1:1 to 1:5 (w / v).

[0053] Preferably, the method for using the aquatic product preservative for alleviating the deterioration of aquatic product quality comprises:

[0054] S1: dissolving an aquatic product preservative that can alleviate the decline in the quality of aquatic products in a solvent to prepare a preservative aqueous solution;

[0055] The concentration of the honeysuckle extract in the aqueous preservative solution is 12 to 20 mg / mL;

[0056] S2: Immersing the aquatic product in the aqueous solution of the preservative at a mass volume ratio of 1:1 to 1:5, immersing at 4 to 25° C. for 10 to 20 minutes, and then draining to obtain the treated aquatic product.

[0057] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0058] The following embodiments, comparative examples and experimental examples are used to illustrate the aquatic preservative for alleviating the deterioration of aquatic product quality in the present application by taking white shrimp as an example. The materials and reagents used in the following embodiments, comparative examples and experimental examples include:

[0059] 1. Brij-35 (L-β-3,4-dihydroxylphenyl)alanine or L-DOPA) was purchased from Sigma-Aldrich, USA.

[0060] 2. 4-HR (4-hexylresorcinol) was purchased from Guangzhou Qiyun Biotechnology Co., Ltd.

[0061] 3. Honeysuckle extract (yellow-brown powder extracted by water) was purchased from Xi'an Baitai Biotechnology Co., Ltd. The concentration ratio was 10:1, that is, 1 kg of honeysuckle extract was prepared from 10 kg of honeysuckle dry powder by conventional water extraction process.

[0062] 4. The trace malondialdehyde (MDA) detection kit was purchased from Beijing Solebow Technology Co., Ltd. All other reagents were of analytical grade.

[0063] Example 1 Analysis of the components of honeysuckle extract purchased from Xi'an Baitai Biotechnology Co., Ltd.

[0064] The specific method for analyzing the components of the honeysuckle extract is as follows:

[0065] The main components of honeysuckle extract were determined by LC-MG plant targeted metabolomics analysis. Based on retention time, fragmentation pattern and comparison with the database, more than 1,800 compounds representing different categories (phenolic acids, flavonols and flavonoids B, cinnamic acid and its derivatives, organic acids and their derivatives, benzoic acid and its derivatives) were identified.

[0066] The main active ingredients are shown in Table 1.

[0067] Table 1:

[0068]

[0069]

[0070]

[0071] Targeted metabolomics results showed that honeysuckle extract was rich in phenolic acids, flavonoids, cinnamic acid and other polyphenols, among which phenolic acid compounds accounted for 18.2%, flavonols and flavonoids accounted for 29.0%, cinnamic acid and its derivatives accounted for 0.5%, organic acids and their derivatives accounted for 10.4%, and benzoic acid and its derivatives accounted for 0.4%.

[0072] Example 2

[0073] The honeysuckle extract provided in Example 1 was used to verify the inhibitory effect of the honeysuckle extract on polyphenol oxidase (PPO) and the inhibitory effect on Cu 2+ The chelation effect is as follows:

[0074] (I) PPO extraction:

[0075] The shrimp heads and thorax were separated, and the fresh shrimp heads were immediately frozen in liquid nitrogen and ground into powder using a food processor. The powder was placed in a polyethylene bag and stored at -80°C for use in extracting PPO within 1 week.

[0076] PPO was extracted from the powder and slightly adjusted. The pH of the extracted PPO phosphate buffer was adjusted from 7.2 to 7.5 to maintain the activity of PPO in the extracted shrimp. All processes were carried out at 4°C.

[0077] The precipitate was dispersed in 0.05 mol / L phosphate buffer (pH 7.5). The powder (100 g) was mixed with 300 mL of extraction buffer (0.05 M sodium phosphate buffer, pH 7.5, containing 1.0 M NaCl and 0.2% Brij 35), and the mixture was stirred for 30 minutes, and then centrifuged at 8000 × g for 30 minutes using a refrigerated centrifuge (Avanti JXN-26, Beckmancoulter., California, USA), and the supernatant was extracted and stored.

[0078] In order to precipitate PPO as much as possible, solid ammonium sulfate was added to the supernatant to reach 40% saturation, and then allowed to stand for 30 minutes. The same buffer was replaced at least three times as the dialysate. After the insoluble material was precipitated, the supernatant was taken out by centrifugation (4°C, 4000×g) and was the PPO enzyme solution, which was stored at 4°C (used within 12 hours).

[0079] (II) Effects of different concentrations of honeysuckle extract on PPO:

[0080] The effect of honeysuckle extract on PPO was studied using L-DOPA as substrate. The honeysuckle extract of Example 1 was dissolved in distilled water at concentrations of 4, 8, 12, 16 and 20 mg / mL.

[0081] The honeysuckle extract solution (1 mL) and the PPO extract (1 mL) were mixed to obtain final extract concentrations of 2, 4, 6, 8 and 10 mg / mL, respectively. The mixture was incubated at 45°C for 30 min, and then 4 mL of phosphate buffer solution (pH 6.0) was added.

[0082] In order to make the reaction proceed fully, 600 mL of L-DOPA solution (15 mmol / L) preheated to 45°C was added to the mixture. After incubation at 45°C for 3 min, the absorbance of the mixture was measured at a wavelength of 475 nm using a UV-2550 spectrophotometer (Shimadzu Scientific Instrument Co., Ltd., Suzhou, China). The enzyme activity was calculated based on the change in absorbance.

[0083] PPO inhibitory activity is expressed as inhibition percentage, and the formula is as follows:

[0084]

[0085] A is the PPO activity of the control group, and B is the PPO activity of the treatment group with the addition of honeysuckle extract.

[0086] Figure 1 This is a graph showing the PPO inhibitory activity of honeysuckle extracts at different concentrations. Figure 1 Different lowercase letters in the same index indicate significant differences (P<0.05).

[0087] Depend on Figure 1 It can be seen that the melanization of shrimp is usually caused by the catalytic oxidation activity of PPO. The melanization of shrimp is affected by the activity of PPO. As the activity of PPO increases, the development of melanization becomes faster accordingly. The PPO inhibitory activity of honeysuckle extract increases with the increase of extract concentration and shows a dose-dependent manner ( Figure 1 ). In particular, when the concentration exceeded 8 mg / mL, the inhibitory effect of honeysuckle extract on PPO was significantly enhanced. When it exceeded 16 mg / mL, the inhibitory effect of honeysuckle extract on PPO activity increased slowly, or even did not increase significantly.

[0088] (three), Cu 2+ Chelating activity assay

[0089] Prepare a 0.1 mol / L copper sulfate solution containing 10 mg / mL sodium nitrate for later use. 10 mg / mL sodium nitrate is used to dilute the 0.1 mol / L copper sulfate solution to 10 -2 , 10-3 , 0 -4 , 10 -5 and 10 -6 mol / L standard solution.

[0090] The electrode potential E (millivolt) of a series of copper standard solutions was measured using an ion meter (Raymagnetic ion meter PXSJ-216) and E pair-lg Cu was plotted. 2+ Standard curve. Prepare 1, 5, 10, 15 and 20 mg / mL honeysuckle extract (containing 10 -3 mol / LCu 2+ and 10g / L sodium nitrate) solution. After the reaction equilibrium is completed, stir at a constant speed at 37°C, and then use an ion meter to measure the E value of solutions with different concentrations. 2+ The chelation rate is calculated as follows:

[0091]

[0092] Where A represents the remaining Cu 2+ Concentration, mol / L; B represents total Cu 2+ Concentration, mol / L.

[0093] Figure 2 The copper chelating activity of honeysuckle extracts at different concentrations. Figure 2 Different lowercase letters in the same index indicate significant differences (P<0.05).

[0094] Depend on Figure 2 It can be seen that the Cu 2+ The chelating activity first increased rapidly with the increase of honeysuckle concentration until 15 mg / mL; when the concentration of honeysuckle exceeded 15 mg / mL, Cu 2+ Chelating activity increases slowly ( Figure 2 ). Cu of honeysuckle 2+ The chelating activity is consistent with its inhibitory effect on PPO activity. 2+ Chelation is one of the methods to inhibit PPO in shrimp.

[0095] Example 3 Shrimp Refrigerated Storage Experiment

[0096] (I) Preparation of prawns:

[0097] Purchase fresh, non-pregnant whiteleg shrimp of uniform size (40 / kg) from Zhanjiang Huanle Haiyang Aquatic Market. Put the shrimp into polyethylene plastic bags, aerate them to keep them alive, and transport them to the laboratory within 1 hour. Select fresh shrimp of the same size and similar body color. Rinse them three times with sterile water and anesthetize them in ice water to kill them. Drain the shrimp and perform further immersion treatment. All shrimp are randomly divided into three equal portions (40 shrimp / portion).

[0098] According to the study on the inhibitory effect of different concentrations of honeysuckle on PPO in step (ii) of Example 2, the optimal immersion concentration of the honeysuckle extract (LJT) of Example 1 is 15 mg / mL.

[0099] Test group 1: One of the three equal parts of shrimp was soaked in a 15 mg / mL solution of honeysuckle extract (LJT) of Example 1, with a shrimp / liquid ratio of 1:2 (w / v), at 4°C for 15 min. The treated shrimp was then placed on a strainer at 4°C to drain for 3 min.

[0100] Test Group 2: Based on the maximum amount of 4-HR (4-hexylresorcinol) allowed for use, 20 mg / mL, another portion of shrimp was immersed in 20 mg / mL 4-HR at 4°C, with a ratio of 1:2 (w / v), for 15 minutes. The treated shrimp was then placed on a strainer at 4°C to drain for 3 minutes.

[0101] Experimental group 3: shrimps were not treated as a control.

[0102] After all samples were processed, they were placed in polyethylene plastic bags and stored at 4°C. Samples were randomly collected every 3 days and their biochemical indicators were tested and analyzed until the 9th day.

[0103] (II) Processing result image:

[0104] Figure 3 These are photos of whiteleg shrimp from experimental groups 1 to 3 during refrigeration.

[0105] Depend on Figure 3 It can be seen that the visual changes of shrimp directly affect consumers' purchasing desire and are also the most direct indicator for evaluating the blackening of shrimp.

[0106] like Figure 3 As shown, at the beginning of storage (the first day), all samples had the transparency, brightness and yellow-green color that are unique to shrimp. As the storage time increased, the color of the shrimp gradually turned black. On the third day of storage, the head, tail and shell of the shrimp in the control group turned black, but the color of the shrimp in experimental groups 1 and 2 treated with 4-HR and honeysuckle did not change significantly. On the sixth day of storage, the shrimp heads, tails and backs of experimental groups 1 (honeysuckle group) and experimental group 2 (4-HR group) all turned black, but the degree of blackening in the honeysuckle group was much lower than that in the other two groups. On the ninth day of storage, the color of experimental group 3 (control group) was the darkest, especially the cephalothorax (head), tail, exoskeleton and arthropods. The samples of experimental group 1 treated with honeysuckle extract only showed slight blackening in the tail, joint legs, cephalothorax and exoskeleton. These results show that both honeysuckle and 4-HR groups can inhibit the blackening of shrimp, and the inhibitory effect of the honeysuckle group is better than that of 4-HR.

[0107] Figure 4 This is a quantitative image analysis diagram of the degree of blackening of samples in test groups 1 to 3 during storage. Figure 4 The mean values ​​with different capital letters in different treatments were significantly different (P<0.05); the mean values ​​with different lowercase letters in different treatments on the same day were significantly different (P<0.05).

[0108] Depend on Figure 4 It can be seen that with the extension of storage time, the degree of blackening of all samples gradually increased (P<0.05). During the storage period, the degree of blackening of test group 1 (honeysuckle group) and test group 2 (4-HR group) was significantly lower than that of test group 3 (P<0.05).

[0109] At the same time, no obvious melanization was found in the shrimp samples treated with honeysuckle extract and 4-HR within 3 days of storage (P>0.05), but on the 6th day, the melanization in the honeysuckle group was significantly lower than that in the 4-HR group (P<0.05), indicating that honeysuckle extract is superior to 4-HR in inhibiting melanization.

[0110] (III) Total bacterial count (TVC)

[0111] Total bacterial count (TVC) is an important reason for the quality decline of shrimp during storage.

[0112] The total bacterial count (TVC) was determined according to the Chinese national standard GB4789.2-2022 (2022). First, the shrimp samples were headed, shelled, and visceral, and the shrimp meat was beaten into minced meat. The shrimp sample (5 g) was added to 45 mL of sterile saline (NaCl, 8.5 g / L), and then homogenized at room temperature for 1 min using a BM-400HP sterile beating homogenizer (Shanghai Chubai Laboratory equipment Co., Ltd., Shanghai, China). The homogenate solution was diluted with sterile saline in a decimal gradient to three consecutive appropriate gradients. Take 100 μL of the dilution and place it on a pre-prepared sterile plate count agar medium, and spread it evenly with a spreading rod. After culturing at 30°C for 48 h, count and determine the TVC.

[0113] Figure 5 This is a quantitative image analysis of the total number of colonies in samples of test groups 1 to 3 during storage. Figure 5 The mean values ​​with different capital letters in different treatments were significantly different (P<0.05); the mean values ​​with different lowercase letters in different treatments on the same day were significantly different (P<0.05).

[0114] like Figure 5As shown in the figure, on day 0, the initial TVC value of fresh shrimp was 3.49 log CFU / g. As the storage time increased, the number of microorganisms in shrimp muscle gradually increased. During the entire storage process, the TVC treated with honeysuckle and 4-HR was lower than that of the control group (P<0.05), and the TVC treated with honeysuckle was lower than that of 4-HR (P<0.05), indicating that both honeysuckle and 4-HR have antibacterial ability, and the antibacterial ability of honeysuckle is better than that of 4-HR.

[0115] (IV) Total volatile basic nitrogen (TVB-N):

[0116] As an important indicator to measure the freshness and quality of shrimp, TVB-N refers to alkaline nitrogen-containing substances such as ammonia and amines produced by the decomposition of protein due to the action of enzymes and bacteria during the spoilage process of animal food.

[0117] Total volatile basic nitrogen (TVB-N) is based on the Chinese standard GB5009.228-2016 (2017) with slight modifications. The calibration solution is a standard hydrochloric acid solution with a concentration of 0.100 mol / L. Kjeldahl nitrogen analyzer (Vapodest 450, C. Gerhardt, Germany) are set as follows:

[0118] The volume of water and alkaline solution is 0, the volume of boric acid receiving solution is 30 mL, and the distillation time is set to 3 min. Remove the shrimp heads, shells, and shrimp threads, and use a food processor (Jiuyang JYL-C230, Joyoung Co., Ltd., Jinan, China) to beat the shrimp meat into minced meat. Put 5 g (accurate to 0.01 g) of shrimp minced meat into a 50 mL centrifuge tube, then add 37.5 mL of pure water and 0.4 g of magnesium oxide. Oscillate the mixture for 30 seconds to mix evenly, and then transfer the mixture to a Kjeldahl nitrogen automatic analyzer (Vapodest450, C. Gerhardt, Germany). The dedicated digestion bottle is immediately connected to the distiller to determine the volatile basic nitrogen content. TVB-N content is expressed in milligrams of nitrogen per 100g of shrimp, and the calculation formula is as follows:

[0119]

[0120] Wherein, V1 represents the volume of hydrochloric acid standard titration solution consumed by the test solution, mL; V2 represents the volume of hydrochloric acid standard titration solution consumed by the reagent blank, mL; c represents the concentration of hydrochloric acid standard titration solution, mol / L; 14 is the mass of nitrogen equivalent to 1 hydrochloric acid [c(HCl)=1.000mol / L], the mass of nitrogen in the standard titration solution, g / mol; m is the sample mass, g; 100 is the conversion factor for converting the calculated result into milligrams per 100 grams, mg / 100g.

[0121] Figure 6 This is a quantitative image analysis diagram of the total volatile basic nitrogen of samples in test groups 1 to 3 during storage. Figure 6 The mean values ​​with different capital letters in different treatments were significantly different (P<0.05); the mean values ​​with different lowercase letters in different treatments on the same day were significantly different (P<0.05).

[0122] like Figure 6 As shown in the figure, with the extension of storage time, the TVB-N values ​​of each group increased significantly. The higher the TVB-N content, the more amino acids were damaged, especially methionine and tyrosine. At the same time, the high TVB-N content means that the nutritional value of shrimp muscle is lost more. During the entire storage process, the increase rate of experimental groups 1 to 3 was different. The TVB-N content of the control sample of experimental group 3 was the highest, followed by the sample of experimental group 2 (4-HR), while the TVB-N content of the honeysuckle sample was the lowest (P<0.05). Therefore, the honeysuckle group obtained a lower TVB-N and better maintained the fresh quality of the shrimp.

[0123] (V) Thiobarbituric acid value (TBARS)

[0124] Lipid oxidation rancidity is one of the main reasons for the deterioration of seafood flavor and is also an important factor affecting the quality of aquatic products. TBARS is a commonly used indicator for evaluating lipid oxidation, which evaluates the degree of lipid oxidation through malondialdehyde, a secondary product of lipid oxidation.

[0125] TBARS in shrimp muscle was determined according to the method of Shiekh (2019). MDA content of shrimp was determined using an MDA content detection kit (Beijing Soleibao Technology Co., Ltd., Beijing, China) and calculated as follows:

[0126]

[0127] Where: ΔA 532 =ΔA 532样品 -ΔA 532空白 ,ΔA 600 =ΔA 600样品 -ΔA 600空白; ΔA 532 and ΔA 600 are the absorbance of the sample at 532nm and 600nm respectively; ΔA 532空白 and ΔA 600空白 are the absorbance of blank at 532nm and 600nm respectively; W is the mass of the sample, W=0.1g.

[0128] Figure 7 This is a quantitative image analysis diagram of the thiobarbituric acid values ​​of samples in test groups 1 to 3 during storage. Figure 7 The mean values ​​with different capital letters in different treatments were significantly different (P<0.05); the mean values ​​with different lowercase letters in different treatments on the same day were significantly different (P<0.05).

[0129] like Figure 7 As shown in the figure, the initial TBARS values ​​of all samples in experimental groups 1 to 3 were 1.60 to 1.72 mg MDA / kg, and there was no significant difference in the TBARS values ​​of all samples (P>0.05). This is because at the beginning of storage, the shrimp had just died and had not experienced severe oxidation, so there was no significant difference in TBARS between the treatment groups. As the storage time increased, the TBARS values ​​of all shrimp gradually increased.

[0130] See also Figure 7 , the TBARS value growth rate of experimental group 3 (control group) was the highest, followed by experimental group 2 (4-HR treatment group), while the growth rate of experimental group 1 (honeysuckle extract) was the lowest. During the first 3 days, the TBARS content of the control group and the 4-HR treatment group increased slightly (P<0.05), but the honeysuckle extract did not increase significantly (P>0.05). The results on the 6th day showed that the TBARS content of the honeysuckle and 4-HR groups was much lower than that of the blank group. Until the end of the 9th day of storage, the TBARS of all experimental groups did not exceed the maximum allowable content of 5mg MDA / kg in seafood.

[0131] Example 4

[0132] Correlation analysis and principal component analysis of freshness index in treatments of experimental groups 1 to 3.

[0133] Figure 8 This is a correlation analysis chart of the freshness index in different treatments of experimental groups 1 to 3.

[0134] like Figure 8As shown in the figure, melanization was significantly positively correlated with TVC (total bacterial colony count), TVB-N (total volatile basic nitrogen) and TBARS (thiobarbituric acid value). The correlation coefficients between melanization and TVB-N and TBARS were 0.95 and 0.94, respectively, which were higher than 0.88 of TVC. Correlation analysis showed that the degree of melanization, TVC, TVB-N and TBARS had a mutually reinforcing effect.

[0135] Fig. 9 This is the principal component analysis diagram of the freshness index in different treatments of experimental groups 1 to 3.

[0136] like Fig. 9 As shown in the figure, there are significant differences between shrimps soaked under different conditions and stored for different periods of time. Throughout the storage period, all samples can be roughly divided into four groups:

[0137] The first group included honeysuckle-0, honeysuckle-3, control-0 and 4-HR-0, which were shrimps with the lowest melanin, TVC, TVB-N and TBARS values. The second group included honeysuckle-6, control-3 and 4HR-3 samples with relatively low melanin, TVC, TVB-N and TBARS values. The third group included 4-HR-6 and control-6, which had relatively high melanin, TVC, TVB-N and TBARS values; the fourth group included honeysuckle-9, 4-HR-9 and control-9, which had the highest melanin, TVC, TVB-N and TBARS values.

[0138] The results showed that honeysuckle had the greatest effect on the fresh-keeping quality of shrimp during cold storage, mainly improving the fresh-keeping quality of shrimp from 0-3d and 3-6d, while the effect on 6-9d was smaller. In the PC1 direction, the degree of blackening, TVC, TVB-N and TBARS were positively correlated. The results of principal component analysis showed that there was a related promotion effect among the four indicators. Therefore, from the correlation analysis and principal component analysis of the above freshness index, it can be seen that test groups 1 and 2 have an inhibitory effect on blackening, TVC, TVB-N and TBARS on the 0th and 3rd days. The principal component scores of the samples treated with test groups 1 and 2 for 6d were similar to those of test group 3 for 3d. Compared with test group 3, test groups 1 and 2 first showed an inhibitory effect on microbial growth. The honeysuckle group had the best inhibitory effect on various detection indicators during storage.

[0139] Based on the above experiments, it can be seen that honeysuckle extract can effectively inhibit PPO activity and chelate Cu in a dose-dependent manner. 2+. Compared with 4-HR, the group treated with honeysuckle extract during cold storage of white shrimp had a brighter appearance, indicating that honeysuckle has the potential to inhibit the melanization of shrimp. Compared with 4-HR, honeysuckle has a stronger antibacterial ability and can better maintain the freshness of shrimp. Its TVC value and TVB-N value are lower than 4-HR. In addition, honeysuckle extract can also inhibit lipid oxidation of shrimp during cold storage, and its TBARS value is the lowest among all groups. It can be seen that honeysuckle is a potential shrimp preservative that can inhibit the melanization, corruption and oxidation of shrimp during cold storage.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A seafood preservative for alleviating the decline in the quality of aquatic products, characterized in that: The aquatic product preservative comprises honeysuckle extract and auxiliary materials acceptable as a preservative.

2. The aquatic product preservative according to claim 1, characterized in that: The honeysuckle extract is honeysuckle water-extracted powder; Preferably, in the honeysuckle water extract powder, calculated by percentage of components, the content of phenolic acid compounds is ≥18.2%, the content of flavonols and flavonoids is ≥29.0%, the content of cinnamic acid and its derivatives is ≥0.5%, the content of organic acids and their derivatives is ≥10.4%, and the content of benzoic acid and its derivatives is ≥0.4%.

3. The aquatic product preservative according to claim 1, characterized in that: The aquatic product preservative can be applied to aquatic products such as crustaceans, preferably any one of shrimps and crabs.

4. A method for using the aquatic product preservative according to any one of claims 1 to 3 to alleviate the decline in the quality of aquatic products, characterized in that: The method of use includes: The aquatic preservative for alleviating the quality decline of aquatic products is dissolved in a solvent to prepare a preservative aqueous solution; then the aquatic product is immersed in the preservative aqueous solution for immersion treatment, and then drained to obtain the treated aquatic product.

5. The method for using the aquatic product preservative for alleviating the decline in the quality of aquatic products according to claim 4, characterized in that: The concentration of the honeysuckle extract in the preservative aqueous solution is 12-20 mg / mL.

6. The method for using the aquatic product preservative for alleviating the decline in the quality of aquatic products according to claim 4, characterized in that: The solvent is water.

7. The method for using the aquatic product preservative for alleviating the decline in the quality of aquatic products according to claim 4, characterized in that: The temperature for immersing the aquatic product in the preservative aqueous solution for treatment is 4-25°C.

8. The method for using the aquatic product preservative for alleviating the deterioration of the quality of aquatic products according to claim 4, characterized in that: The time for immersing the aquatic product in the preservative aqueous solution for treatment is 10 to 20 minutes.

9. The method for using the aquatic product preservative for alleviating the decline in the quality of aquatic products according to claim 4, characterized in that: The mass volume ratio of the aquatic product to the preservative aqueous solution is 1:1 to 1:5 (w / v).

10. The method for using the aquatic product preservative for alleviating the deterioration of the quality of aquatic products according to claim 4, characterized in that: The method of use includes: S1: dissolving an aquatic product preservative that can alleviate the decline in the quality of aquatic products in a solvent to prepare a preservative aqueous solution; The concentration of the honeysuckle extract in the aqueous preservative solution is 12 to 20 mg / mL; S2: Immersing the aquatic product in the aqueous solution of the preservative at a mass volume ratio of 1:1 to 1:5, immersing at 4 to 25° C. for 10 to 20 minutes, and then draining to obtain the treated aquatic product.

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