Method for preserving mackerel by combining ozone water with compound preservative and application of mackerel

Abstract

The invention provides a method for preserving mackerel with combination of ozone water and a compound preservative and application of the mackerel, the method comprises the following steps: after baking fish blocks, soaking the fish blocks with ozone water for sterilization, and in the storage process, plating ice glaze on the surfaces of the fish blocks with the compound preservative, the compound preservative comprises 0.1-1% of trehalose, 0.05-0.35% of tea polyphenol and 0.05-0.35% of vitamin E. The invention also provides a method for preserving mackerel with combination of ozone water and the compound preservative. According to the method, ozone water is adopted for cold sterilization of the surfaces of the cooked mackerel blocks, microorganisms in the mackerel meat processing process can be widely and efficiently killed, water loss and lipid oxidation of the mackerel blocks in the storage process can be obviously inhibited by using the compound preservative for ice glazing treatment and conditioning of the mackerel blocks, the number of microorganisms in the mackerel blocks is reduced, and the quality of the mackerel meat is improved. The storage period and shelf life of the product are prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of aquatic product preservation and processing, and specifically relates to a method for preserving Spanish mackerel using ozone water combined with a composite preservative and application thereof. Background Art

[0002] Spanish mackerel, also known as Spanish mackerel, belongs to the pelagic fish in the nearshore area. It has a very rich annual output and is one of the important marine economic fish in my country. However, it is still in the primary processing stage with simple processing methods such as fresh cooking, quick freezing whole fish or slices, smoking, and fish paste products. The convenient products and comprehensive utilization of Spanish mackerel can be explored. Spanish mackerel meat is firm, with less bones and slightly acidic. It tastes very delicious and is rich in nutrition. It contains more than 19 grams of protein per 100 grams of fish meat. Compared with other fish, Spanish mackerel has a higher content of unsaturated fatty acids, second only to tuna, so it is more perishable, making it more prone to lipid oxidation during storage. For example, some freshwater fish such as carp and grass carp, although they also contain a certain amount of unsaturated fatty acids, their content is lower than that of Spanish mackerel, so the difficulty of preservation and storage is relatively small. In order to extend the shelf life of Spanish mackerel, low temperature storage technology is usually required, but Spanish mackerel is highly sensitive to low temperatures. Too low a temperature may cause the fish meat to become hard and the taste to deteriorate. Therefore, a series of measures need to be taken during the storage of Spanish mackerel to extend its shelf life and maintain its quality.

[0003] In the field of fish preservation, traditional methods mainly include low-temperature preservation, salt preservation, vacuum packaging, and chemical preservatives. Low-temperature preservation, such as refrigeration and freezing, slows down the growth of microorganisms and the activity of enzymes by lowering the temperature, thereby extending the shelf life of fish. However, this method may cause changes in the texture and taste of fish. Salt preservation inhibits the growth of microorganisms through a high-salt environment, but too much salt will affect the taste and nutritional value of fish. Vacuum packaging inhibits the growth of microorganisms by reducing the oxygen content, but long-term storage may cause oxidation and deterioration of fish. Chemical preservatives extend the shelf life by adding chemical substances with antibacterial effects, but there may be certain food safety risks. Therefore, at this stage, fish preservation should adopt a composite storage method to meet the requirements of the times.

[0004] Patent document CN107173425B discloses a compound preservative for fresh fish fillets and its application. Live fish pieces are washed and soaked with ozone and then treated with a compound preservative before storage. The application mainly uses a compound preservative to inhibit bacteria, protect color and flavor. The compound preservative provided has various ingredients and a complicated preparation process. The fish fillets it preserves are mainly general fish such as grass carp, bighead carp or silver carp, and may not meet the needs of fish species such as Spanish mackerel that are difficult to preserve and store.

[0005] Therefore, providing a composite preservation method for extending the shelf life of Spanish mackerel and maintaining its quality is of great significance to improving the nutritional value and quality of Spanish mackerel. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for preserving Spanish mackerel by using ozone water combined with a composite preservative and its application, wherein ozone water is used to effectively kill microorganisms on the surface of fish meat, inhibit the growth and reproduction of bacteria, and extend the shelf life; secondly, the Spanish mackerel soaked in ozone water is further treated with a composite preservative to further delay the spoilage process of the fish meat and maintain its nutritional value and flavor. The Spanish mackerel treated by the preservation method of the present invention can significantly extend its shelf life, and the quality, taste and nutritional value of the fish meat are also effectively maintained.

[0007] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0008] In one aspect, the present invention provides a composite preservative comprising trehalose, tea polyphenols and vitamin E.

[0009] Trehalose is a non-reducing sugar that is non-toxic and sweet. Trehalose is mainly obtained from corn, cassava and other starches through biological fermentation technology. It is a safe and reliable natural sugar. Trehalose has excellent moisturizing and water-locking properties. Its molecular structure is easy to combine with water molecules to form a stable structure, thereby effectively reducing the loss of water in food during storage. Trehalose also has excellent antioxidant properties, which can protect the antioxidant components in food, thereby delaying the oxidation process of food and significantly extending its shelf life while maintaining the flavor and nutritional value of food. Tea polyphenols are an effective natural antioxidant, rich in a variety of phenolic hydroxyl structures, and show extremely strong antioxidant activity. In the process of food preservation, tea polyphenols can effectively scavenge free radicals and slow down the oxidation reaction of food, thereby inhibiting the oxidative decomposition of nutrients such as lipids, proteins and vitamins in food, and significantly extending the shelf life of food.

[0010] Furthermore, the composite preservative comprises 0.1-1% trehalose, 0.05-0.35% tea polyphenols and 0.05-0.35% vitamin E.

[0011] In some embodiments, the present invention verifies the necessity of preparing a composite preservative by combining 0.1-1% trehalose, 0.05-0.35% tea polyphenols and 0.05-0.35% vitamin E. The results show that the use of one or two of trehalose, tea polyphenols or vitamin E to preserve fish meat has no obvious effect on the scavenging of free radicals and the inhibition of lipid oxidation. The composite preservative composed of trehalose, tea polyphenols and vitamin E has a synergistic effect in improving the antioxidant effect and delaying the degradation of amino acids in fish meat. At the same time, compared with combinations of substances with antioxidant activity such as chitosan oligosaccharides, plant essential oils or vitamin C, it is also found that the antioxidant effect of the composite preservative provided by the present invention is significantly better than that of other combined preservatives.

[0012] Trehalose, tea polyphenols and vitamin E are all non-toxic and harmless, highly safe, and rich in antibacterial and antioxidant active substances. Trehalose can effectively inhibit the fatty acid rancidity process, reduce the decomposition of fatty acids and the generation of odorous substances in food, while the fresh taste of tea polyphenols can add a unique flavor to food and enhance the sensory quality of food.

[0013] On the other hand, the present invention provides a method for preserving Spanish mackerel, which uses the composite preservative as described above to preserve Spanish mackerel.

[0014] Furthermore, the mackerel pieces are firstly soaked and sterilized in ozone water, and then an ice coating is applied on the surface of the fish pieces by a composite preservative to preserve the freshness.

[0015] Compared with other fish, Spanish mackerel has a higher content of unsaturated fatty acids, so it is more susceptible to corruption, which makes it more prone to lipid oxidation during storage, and the difficulty of preservation and storage is higher. Therefore, in order to extend the shelf life of Spanish mackerel and maintain its quality, the present invention proposes a method for preserving Spanish mackerel with ozone water combined with a composite preservative, which, on the one hand, utilizes the strong oxidizing property of ozone to effectively kill microorganisms on the surface of fish meat, and on the other hand, utilizes the composite preservative to adjust the pH value and water activity of fish meat, avoid the decomposition of specific flavor amino acids such as glutamic acid and aspartic acid, further delay the corruption process of fish meat, and maintain its nutritional value and flavor.

[0016] As an advanced food preservation technology, ice coating for preserving fish has been widely used in the field of fishery processing in recent years. This technology forms a thin layer of ice film on the surface of fish to achieve physical protection and preservation of fish. Traditional ice coating uses tap water, which cannot inhibit the growth of microorganisms in fish products, accelerates the spoilage of aquatic products, and seriously affects their quality. This study uses a composite preservative combined with ice coating technology. The composite preservative can not only more effectively inhibit the growth of microorganisms, but also has an antioxidant effect, slowing down the decline in the quality of fish pieces; and the ice coating technology can effectively reduce the loss of water in meat. The composite preservative is used to coat the mackerel pieces with ice, avoiding the effect of low temperature on the quality of mackerel, slowing down the degradation rate of amino acids and the reproduction rate of microorganisms, and delaying the change of myofibrillar protein conformation in fish meat, thereby maintaining the hardness, protein content and quality of fish meat. This method not only combines the advantages of traditional ice coating technology, but also provides a more comprehensive and in-depth preservation effect for fish meat through the addition of composite preservatives.

[0017] Furthermore, the concentration of the ozone water is 0-4 mg / L, and the soaking time is 0-12 min.

[0018] Ozone water has a strong ability to kill bacteria and disinfect. It can quickly destroy the cell structure of microorganisms, thereby achieving a sterilization effect. It can not only kill bacteria, viruses, fungi and other microorganisms in water, but also remove odors and organic matter in water. Ozone water can not only improve the sanitary quality of food and extend the shelf life of food, but also reduce production costs and environmental pollution.

[0019] Preferably, the concentration of the ozone water is 2.5 mg / L, and the soaking time is 9 minutes.

[0020] In some embodiments, ozone water with different soaking time (0-12 min), ozone water concentration (0-4 mg / L), liquid-to-solid ratio (3-10:1), and ozone water temperature (0-20° C.) is prepared to obtain the ozone water for sterilizing fish chunks described in the present invention.

[0021] In some embodiments, the present invention uses the immersion time, concentration, liquid-to-solid ratio and temperature conditions of ozone water as investigation factors to conduct orthogonal experiments. The results show that when the concentration of ozone water is 2.5 mg / L, the temperature is 6°C, the liquid-to-solid ratio is 9:1, and the immersion time is 9 minutes, the number of colonies in the fish meat is the least, indicating that the antibacterial effect of ozone water is best under this condition.

[0022] Furthermore, the preservation method comprises the following steps:

[0023] (1) Pretreatment: slicing, marinating, roasting, cooling, and cutting the mackerel;

[0024] (2) Sterilization treatment: soak the fish pieces obtained in step (1) in ozone water for 8 to 12 minutes and then remove them;

[0025] (3) Ice coating treatment: the fish block obtained in step (2) is quickly frozen at low temperature, and after freezing, it is placed in a composite preservative and soaked for 5 to 10 minutes, then taken out and frozen, and the operation is repeated until a 1 to 2 cm ice coating is formed on the surface of the fish block;

[0026] (4) Low temperature treatment: The mackerel pieces obtained in step (3) are vacuum packed and then stored.

[0027] Furthermore, in step (2), the temperature of the ozone water is 0-20° C., and the liquid-to-material ratio of the ozone water to the mackerel chunks is (3-10):1.

[0028] Preferably, in step (2), the immersion time of the fish pieces in the ozone water is 9 minutes, the liquid-to-material ratio of the ozone water to the fish pieces is 9:1, the concentration of the ozone water is 2.5 mg / L, and the temperature is 6°C.

[0029] Preferably, in step (3), the fish blocks are taken out from the ozone water and quickly frozen in a -20°C refrigerator for 20 minutes. After the fish blocks are frozen, they are placed in a composite preservative and soaked for 6 minutes. After soaking, they are taken out and continued to be quickly frozen in a -80°C refrigerator for 30 minutes. Thereafter, the fish blocks are again placed in the composite preservative glaze liquid and soaked for 6 minutes. After soaking, the fish blocks are taken out and frozen in a -20°C refrigerator. The fish blocks coated with the first layer of glaze are again placed in the composite preservative glaze liquid and soaked for 6 minutes. After soaking, they are again placed in a -20°C refrigerator and frozen. This step is repeated 3 times until the surface of the fish blocks is coated with 2-3 cm of glaze.

[0030] On the other hand, the present invention provides a cooked mackerel block, which is prepared by the above-mentioned mackerel preservation method.

[0031] Frozen prepared food refers to packaged food that uses agricultural products, livestock and poultry, and aquatic products as main raw materials, and after pre-treatment and preparation (including seasoning), uses a quick freezing process, and is stored, transported, and sold in a frozen state (below -18°C). With the acceleration of the pace of life of consumers and changes in eating habits, frozen prepared foods are deeply loved by consumers for their convenience, stable quality, rich nutrition, and diverse taste. In some embodiments, the research results of the present invention show that compared with traditional preservation technology, the preservation method provided by the present invention is used to preserve Spanish mackerel meat, which can more effectively adjust the pH value and water activity of the fish meat, further delay the spoilage process of the fish meat, and can also delay the changes in the conformation of myofibrillar protein in the fish meat, thereby maintaining the hardness, protein content and quality of the fish meat.

[0032] In another aspect, the present invention provides a composition for preparing a preservative for inhibiting the growth of microorganisms in fish meat, wherein the composition comprises 0.1-1% trehalose, 0.05-0.35% tea polyphenols and 0.05-0.35% vitamin E.

[0033] Furthermore, the fish meat is mackerel.

[0034] In another aspect, the present invention provides a composition for preparing a preservative for improving the antioxidant effect of fish meat, wherein the composition comprises 0.1-1% trehalose, 0.05-0.35% tea polyphenols and 0.05-0.35% vitamin E.

[0035] Furthermore, the fish meat is mackerel.

[0036] The present invention has the following beneficial effects:

[0037] 1. The method for preserving Spanish mackerel by using ozone water combined with a composite preservative of the present invention can not only achieve freshness preservation and sterilization, but also is easy to operate, safe and environmentally friendly. The composite preservative provided has a simple formula, is easily available, and is conducive to promotion.

[0038] 2. The present invention utilizes a composite preservative to coat the conditioned mackerel chunks with glaze. The composite preservative can effectively inhibit the growth of microorganisms. The glaze preservation method can effectively reduce the loss of moisture in the meat. The combination of the composite preservative and the glaze technology maintains the moisture and nutrition of the fish chunks and extends the shelf life of the product.

[0039] 3. The present invention maintains the original flavor of the prepared product and can achieve quality maintenance during transportation and storage. It has low operating costs and is suitable for various scenarios such as industrial production and household preservation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a comparison chart of the total number of colonies of ozone water under different conditions of the present invention;

[0041] Figure 2 It is a contour map and response surface diagram of the ozone-water interaction term of the present invention;

[0042] Figure 3 The single preservative of the present invention is DPPH - and ABTS + Free radical scavenging ability;

[0043] Figure 4 The effect of different concentrations of the single preservative of the present invention on TBA of frozen prepared fish pieces;

[0044] Figure 5 Schematic diagram of the change of water loss after the fish pieces are preserved with no glaze, pure water glaze and composite preservative glaze in Example 1 of the present invention;

[0045] Figure 6 Schematic diagram of the change of pH value of fish pieces after preservation and conditioning with no glaze, pure water glaze and composite preservative glaze in Example 1 of the present invention;

[0046] Figure 7 It is a schematic diagram showing the change of the total number of bacterial colonies after the fish pieces were preserved with no glaze, pure water glaze and composite preservative glaze in Example 1 of the present invention;

[0047] Figure 8 Schematic diagram of the change of thiobarbituric acid value (TBA) of fish pieces after preservation and conditioning with no glaze, pure water glaze and composite preservative glaze in Example 1 of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below in conjunction with the examples. It should be pointed out that the examples described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0049] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0050] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0051] Example 1: Processing of Spanish mackerel by the method for preserving Spanish mackerel provided by the present invention

[0052] (1) Place pure water in a -20°C freezer for cooling until the temperature reaches ≤6°C, and pass an ozone generator into the low-temperature pure water to produce low-temperature ozone water with a concentration of 2.5 mg / L.

[0053] (2) Take a fresh Spanish mackerel and remove the head, tail, internal organs, and other parts that do not meet the quality requirements. Use running water at 15-20°C to clean the mucus and impurities on the surface of the fish, clean the black film and blood stains in the cavity, drain the surface water, cut into fish pieces with a width of 3-5 cm, remove obvious fish bones, and use kitchen paper to absorb the surface water of the fish pieces.

[0054] (3) Preheat the oven to 150°C for 20 min. Remove the marinated fish pieces and place them on a baking tray. Bake at 150°C for 15 min. Turn the fish over and bake for another 10 min. After baking, bring to room temperature.

[0055] (4) Soak the fish pieces in low-temperature ozone water for 9 minutes, then take them out and quickly freeze them in a -20°C refrigerator for 20 minutes. After the fish pieces are frozen, soak them in a composite preservative for 6 minutes. The composite preservative is prepared by 0.8% trehalose (purchased from Jiahe Xuri Co., Ltd., food grade crystalline trehalose), 0.3% tea polyphenols (purchased from Jiahe Xuri Co., Ltd., food grade), and 0.25% vitamin E (purchased from Jiahe Xuri Co., Ltd., food grade 99% purity).

[0056] (5) After soaking, the fish pieces are taken out and placed in a -80°C refrigerator for quick freezing for 30 minutes. Thereafter, the fish pieces are again placed in the composite fresh-keeping glaze liquid and soaked for 6 minutes. After the fish pieces are soaked, they are taken out and placed in a -20°C refrigerator for freezing.

[0057] (6) Soak the fish pieces coated with the first layer of glaze in the composite preservative glaze solution for 6 minutes again. After soaking, freeze them in a -20°C refrigerator again. Repeat this step 3 times until the surface of the fish pieces is coated with 2-3 cm of glaze. Put them into polyethylene bags, number them, and freeze them in a -18°C refrigerator. Take out samples every 3 days for testing indicators.

[0058] Example 2: Optimization of conditions for ozone water treatment of Spanish mackerel

[0059] Ozone, as a strong oxidant, has a significant killing effect on a variety of microorganisms. Using ozone to treat Spanish mackerel pieces can inhibit the oxidation reaction of lipids in the fish meat, delay rancidity and the generation of odor, and thus maintain the freshness of the fish meat. However, too high an ozone concentration may cause fish protein denaturation or produce an unpleasant odor, so it is necessary to optimize key conditions such as the concentration of ozone water and the treatment time. Therefore, this embodiment optimizes and screens the immersion time, concentration, liquid-to-solid ratio, and temperature conditions of ozone water, as follows:

[0060] (1) The soaking time of ozone water is 0 to 12 min. The other preservation treatment steps are the same as those in Example 1. Then, the total number of colonies on the surface of frozen prepared mackerel blocks after soaking for different times is determined with reference to GB4789.2-2022 "National Food Safety Standard for Food Microbiology Examination and Determination of Total Colony Count". The results are as follows: Figure 1 As shown in A.

[0061] (2) The concentration of ozone water was selected to be 0-4 mg / L. The remaining preservation treatment steps were the same as those in Example 1. The total number of bacterial colonies on the surface of the frozen prepared mackerel blocks after treatment with ozone water of different concentrations was measured. The results were as follows: Figure 1 As shown in B.

[0062] (3) The liquid-to-material ratio of ozone water to mackerel chunks is (3-10):1. The remaining preservation treatment steps are the same as those in Example 1. The total number of bacterial colonies on the surface of the frozen mackerel chunks treated with different liquid-to-material ratios is then measured. The results are as follows: Figure 1 As shown in C.

[0063] (4) The temperature of the ozone water was set to 0-20° C., and the remaining preservation treatment steps were the same as those in Example 1. The total number of bacterial colonies on the surface of the frozen mackerel blocks after being treated with ozone water at different temperatures was then measured. The results were as follows: Figure 1 D. A single factor experiment was used to screen out the four factors and their gradient levels that had a greater impact on the total colony count of cooked fish chunks. The Design-Expert response surface data analysis software was used to complete the test design. The total colony count was used as the test response value (Y). A four-factor three-level response surface optimization experiment was completed, and 29 test groups were obtained, as shown in Table 1.

[0064] Table 1 Response surface experimental design and results

[0065]

[0066] The analysis results were fitted with a multiple regression model using response surface software, and the resulting equation was Y = 2.67 + 0.0116A + 0.0367B + 0.0311C + 0.0247D - 0.0818AB + 0.0216AC + 0.0248AD + 0.0049BC - 0.0457BD - 0.0335CD - 0.2885A 2 -0.2562B 2 -0.2706C 2 -0.2401D 2 .

[0067] The results of variance analysis of the regression equation are shown in Table 2. The F test and lack-of-fit test results of the quadratic regression equation obtained from 29 groups of test points show that the model P < 0.0001, indicating that the model is extremely significant; the lack-of-fit term P = 0.0763> 0.05, indicating that the model has a good degree of fit and has application significance. 2 =0.9758, close to 1, indicating that the model has a good high credibility. 2 Adj =0.9517 is close to 1 and is consistent with R 2 The difference is less than 0.2, and CV% = 2.10 < 10%, which shows that the regression process is consistent with the actual situation and can be used to predict the test results.

[0068] From the analysis of the results, it can be seen that the response value Y (total colony count) model is highly significant, the first-order terms A (immersion time) and D (ozone water temperature) are not significant, B (ozone water concentration) and C (liquid-to-solid ratio) reach a significant level (P<0.05); among the quadratic terms, A2, B2, C2, and D2 all reach an extremely significant level (P<0.01); among the interaction terms, only AB reaches an extremely significant level (P<0.01), and the other interaction terms are not significant. The order of influence of the four factors on the total colony count is B (ozone water concentration)>C (liquid-to-solid ratio)>D (ozone water temperature)>A (immersion time).

[0069] Table 2 Results of variance analysis of response surface experiment

[0070]

[0071] Note: “**” indicates extremely significant effect (P<0.01), “*” indicates significant effect (P<0.05), and “—” indicates insignificant effect.

[0072] The three-dimensional spatial surface and contour map between the four factors were obtained by response surface software ( Figure 2 ), which can more intuitively express the interaction between factors. The elliptical contour lines indicate significant interaction, and the steeper the slope of the three-dimensional surface graph, the more significant the impact.

[0073] like Figure 2 As shown in A, the slope of ozone water concentration is steeper than that of immersion time, indicating that ozone water concentration has a more significant effect on the total colony count of conditioned fish blocks than immersion time. This is because the sterilization effect of ozone is more significant as the concentration of ozone water increases. The contour map is elliptical, and P of AB is <0.01, indicating that the interaction between ozone water concentration and immersion time is significant, and the change range of the total colony count of conditioned fish blocks with ozone water concentration is greater than that of immersion time, and the total colony count of conditioned fish blocks is more significantly affected by ozone water concentration, which is consistent with the results of the above-mentioned variance analysis. It can be found from Figures (C), (E), and (F) that although the contour map is elliptical, its P value is >0.05, indicating that the interaction between immersion time and ozone water temperature, ozone water concentration and ozone water temperature, liquid-to-solid ratio and ozone water temperature is not significant. As can be seen from Figures (B) and (D), the contour map is close to a circle, P>0.05, indicating that the interaction between the immersion time and the liquid-to-solid ratio, the ozone water concentration and the liquid-to-solid ratio is not significant.

[0074] The optimal combination of factor levels predicted by the regression equation is: soaking time 8.91min, ozone water concentration 2.50mg / L, liquid-to-solid ratio 8.96, ozone water temperature 5.96℃, under which the total colony count of conditioned fish pieces is 1.93log(CFU / g). For ease of operation, the above conditions were amended to soaking time 9min, ozone water concentration 2.5mg / L, liquid-to-solid ratio 9:1, and ozone water temperature 6℃. Three parallel tests were conducted under this condition, and the average total colony count of conditioned fish pieces was 1.94lg(CFU / g), which is relatively small compared with the model prediction value, proving that the model has a good degree of fit and is reliable.

[0075] Example 3: Effect of composite preservative on the quality of mackerel chunks

[0076] The composite preservative is crucial for inhibiting the oxidation rate of mackerel pieces and improving the preservative effect of the subsequent glazing technology. During the research process of the present invention, in order to improve the antioxidant effect of the preservative and reduce the loss of nutrients and water in the fish pieces, the present invention screened and optimized the components of the composite preservative to obtain the preservative formula and dosage with the best use effect.

[0077] (1) Screening of compound preservative formula

[0078] Compared with other fish, Spanish mackerel has a higher content of unsaturated fatty acids, so it is more perishable and is more susceptible to lipid oxidation during storage. However, Spanish mackerel is highly sensitive to low temperatures, and too low a temperature may cause the fish meat to become hard and have a worse taste. Therefore, the provided composite preservative needs to have a strong antioxidant effect, which can significantly inhibit the oxidation of Spanish mackerel, while being able to retain moisture in the fish meat and avoid the effects of poor taste of the fish meat caused by processes such as low-temperature storage. The present invention uses substances with moisturizing, antibacterial or antioxidant effects to prepare 10 composite preservatives shown in Table 3, and the 10 composite preservatives are used to treat Spanish mackerel according to the method of Example 1, and the DPPH in the fish meat after 12 days of treatment with different preservatives is determined by spectrophotometry. - Free Radicals and ABTS + The free radical scavenging rate, thiobarbituric acid value (TBA) and amino acid content are shown in Table 3. The initial (day 0) TBA content in Spanish mackerel of different groups was 0.510-0.525 mg MDA / 100 g, the initial (day 0) glutamic acid content was 1.950-1.980 g / 100 g, and the initial (day 0) aspartic acid content was 1.000-1.085 g / 100 g.

[0079] Table 3 Types and ingredients of composite preservatives

[0080]

[0081]

[0082] Table 4 Antioxidant effects of different composite preservatives

[0083]

[0084] As shown in the data in Table 3, by comparing preservatives ① to ⑦, it can be seen that the preservatives (② to ④) prepared using an antioxidant ingredient have a significant effect on DPPH - Free Radicals and ABTS + The free radical scavenging rate is less than 30%. The scavenging rates of preservatives ⑤ to ⑦ for the two free radicals can only reach more than 30%, less than 40%. - Free Radicals and ABTS + The free radical scavenging rates can reach 67.6% and 77.2% respectively, indicating that the antioxidant capacity of trehalose, tea polyphenols or vitamin E alone is limited. Compared with the combination of the two ingredients, the preservative composed of trehalose, tea polyphenols and vitamin E has a significant synergistic effect on improving the antioxidant effect of fish meat. At the same time, by comparing preservatives ①, ⑧~⑩, it can be found that the composite preservative prepared by using chitosan oligosaccharides, plant essential oils or vitamin C has a significant synergistic effect on DPPH - Free Radicals and ABTS + The free radical scavenging ability is not as good as that of compound preservative ①. The fish meat treated with compound preservative ① has the strongest antioxidant capacity and better preservation effect.

[0085] According to the content of TBA and glutamic acid and aspartic acid, it can be found that the TBA content in the fish treated with composite preservative ① is the lowest, only 0.954±0.05mg MDA / 100g, indicating that the degree of lipid oxidation in the fish is the lowest and the fish is fresher; at the same time, the content of glutamic acid and aspartic acid in the fish treated with preservative ① is 1.854±0.24g / 100g and 1.015±0.18g / 100g, respectively, which is significantly higher than that of other groups. The reason may be that compared with other sugars or vitamins, the composite preservative composed of trehalose, tea polyphenols and vitamin E has a synergistic effect in delaying lipid oxidation, further improving the antioxidant effect of the preservative and avoiding amino acid degradation in fish.

[0086] (2) Optimization of the dosage of composite preservative ingredients

[0087] In the composite preservative, the ratio of trehalose, tea polyphenols and vitamin E will directly affect the preservation effect and quality of the fish. Too low a content of each substance will not meet the preservation requirements, while too high a content may affect the flavor or quality, and may further cause a decrease in the subsequent glaze effect. Therefore, in order to determine the amount of the composite preservative that can achieve the best preservation effect, this example further compares and screens the ratios of trehalose, tea polyphenols and vitamin E, and uses 0.1-1% trehalose, 0.05-0.35% tea polyphenols, and 0.05-0.35% vitamin E as single factor variables to prepare composite preservatives I, II, and III, respectively. The remaining preservation treatment steps are the same as in Example 1. The DPPH in the differently treated mackerel was then determined by spectrophotometry. - Free Radicals and ABTS + The free radical scavenging rate and thiobarbituric acid (TBA) content were measured. Figure 3 and Figure 4 At the same time, on the basis of the single factor test, the concentration of three preservatives, trehalose, tea polyphenols and vitamin E, was used as the investigation factor to conduct an orthogonal test. The results of the orthogonal test are shown in the following table.

[0088] Table 5 Orthogonal test results of three preservative concentrations

[0089]

[0090] Combine the results in the table with Figure 3 , 4 It can be seen that R 茶多酚 >R 海藻糖 >R 维生素E That is, the order of influence of the three factors on TBA of fish fillet is tea polyphenol concentration> trehalose concentration> vitamin E concentration. When the trehalose concentration is 0.8%, the tea polyphenol concentration is 0.3%, and the vitamin E concentration is 0.25%, the TBA of frozen prepared fish fillet is the lowest, which is 0.979mg MDA / 100g. - Free Radicals and ABTS + The free radical scavenging rates were 65.394% and 74.146% respectively. Three parallel verification experiments were conducted under this condition, and the average TBA value was 0.9896 mg MDA / 100 g, and DPPH - The average free radical scavenging rate was 63.723%, ABTS + The average free radical scavenging rate was 75.258%, indicating that the preparation process conditions of the composite preservative were stable and had good repeatability.

[0091] Example 4: Beneficial effects of treating mackerel pieces with composite preservative glaze

[0092] In order to further verify that the composite preservative combined with the glaze coating method has a significant beneficial effect on improving the quality of fish meat and extending the storage period of mackerel pieces, the present invention also compares the glaze-free method, pure water glaze preservation and composite preservative soaking, wherein the glaze-free treatment method is different from the method of Example 1 in that the mackerel pieces are directly placed in a -15°C environment for storage after being soaked in ozone water; the pure water glaze preservation method is different from Example 1 in that the composite preservative is replaced with pure water, and the other steps are performed according to the method of Example 1; the composite preservative soaking is different from the method of Example 1 in that the mackerel pieces are directly placed in the composite preservative for 6 minutes after being soaked in ozone water without quick freezing, and then stored after being fished out. Physical and chemical analysis and microbial detection methods are used to analyze and calculate the water loss rate, pH value, TVC content, TBA content, glutamic acid and aspartic acid content and fish meat hardness value of mackerel pieces under different treatment conditions. The specific methods include: the water loss rate is determined by weight method, the pH value is measured by pH meter, the TVC (total volatile basic nitrogen) content is determined by Kjeldahl nitrogen determination or distillation titration, the TBA (thiobarbituric acid) content is determined by colorimetry, the glutamic acid and aspartic acid content is analyzed by high performance liquid chromatography (HPLC), and the fish meat hardness value is determined by texture analyzer. Among them, the results of fish meat hardness and amino acid determination under different treatments are shown in Tables 6, 7 and 8. The water loss rate, pH value, TVC content, and TBA content of the fish without glaze, pure water glaze, and composite preservative glaze treatments are shown in Tables 6, 7 and 8. Figures 5 to 8 shown.

[0093] Table 6 Determination of fish meat hardness under different preservation conditions

[0094]

[0095] According to the data in Table 5, the hardness of Spanish mackerel meat decreased under the four treatment conditions. Among them, the hardness of fish meat without glaze treatment decreased the fastest. When stored for 12 days, the hardness decreased by about 58.02%; the hardness decrease rate can be inhibited to a certain extent after glazing technology or soaking in composite preservatives. Among them, the hardness of fish meat preserved by pure water glaze decreased by about 36.24% after storage for 12 days; the hardness of fish meat soaked in composite preservatives decreased by about 42.60%; the hardness of fish meat glazed with composite preservatives decreased by about 27.44%, indicating that the composite preservative glazing method is the best in maintaining the quality of fish meat. The reason may be that the composite preservative glaze significantly inhibits the growth of microorganisms and the area of ​​contact with oxygen, reducing the degradation of myofibrillar protein in fish meat.

[0096] Table 7 Determination of glutamic acid content under different preservation conditions

[0097]

[0098] Table 8 Aspartic acid determination under different preservation conditions

[0099]

[0100] From the data of amino acid content determination, it can be seen that glutamic acid and aspartic acid in fish meat after preservation under different conditions have undergone different degrees of degradation. When stored for 12 days, the glutamic acid content under the conditions of no glaze, pure water glaze, composite preservative immersion, and composite preservative glaze treatment decreased by 43.81%, 36.23%, 42.13%, and 12.40%, respectively, and the aspartic acid content decreased by 68.46%, 48.4%, 51.22%, and 11.54%, indicating that only the composite preservative glaze can effectively delay the protein degradation in Spanish mackerel meat and avoid the decomposition of specific flavor amino acids such as glutamic acid and aspartic acid, thereby further delaying the spoilage process of fish meat. Only pure water glaze or composite preservative immersion without glaze can not achieve effective preservation effect.

[0101] like Figure 5 As shown, after being treated with no glaze, pure water glaze and preservative glaze and stored for 12 days, the thawing loss of fish meat was 23.12%, 21.093% and 12.841% respectively, and the moisture loss was 95.325%, 92.891% and 81.723% respectively. This shows that the use of composite preservatives combined with glaze can effectively reduce the loss of moisture in fish meat and maintain the moisture and freshness of swordfish.

[0102] According to the pH measurement results, the pH of the mackerel meat under the four treatment conditions decreased significantly from the 0th day to the 9th day of storage, and the pH on the 9th day was 6.90, 6.87, 6.88, and 6.85 respectively. This process is mainly because in the initial stage after the death of the fish, the muscle undergoes energy metabolism and accumulates acidic substances, resulting in a significant decrease in the pH of the tissue. From the 9th day, the fish meat began to rot, the microbial activity increased, and the protein was decomposed to produce alkaline substances, resulting in an increase in pH. It can be found that in this process, the preservation techniques of pure water glaze preservation, composite preservative immersion and composite preservative glaze can slow down the rise in the pH of the fish meat. Among them, the effect of composite preservative glaze is more significant, and the pH value of the fish meat changes less, which is 6.86, indicating that the composite preservative glaze can effectively slow down the decay rate of the fish meat during storage.

[0103] from Figure 7The statistics of the total viable count (TVC) also show that from the 0th day to the 12th day of storage, under the condition of no glaze treatment, the TVC value increases almost linearly, indicating that with the increase of storage time, the microorganisms in the fish meat proliferate significantly and the fish meat gradually becomes corrupt. In contrast, the preservation technology using pure water glaze or composite preservative glaze can effectively inhibit the reproduction of microorganisms. On the 12th day, the TVC contents in the fish meat preserved with no glaze, pure water glaze, composite preservative immersion and composite preservative glaze were approximately 2.94lg (CFU / g), 2.81lg (CFU / g), 2.87lg (CFU / g) and 2.40lg (CFU / g), respectively, which increased by approximately 54.7%, 47.8%, 51.1% and 26.3% respectively compared with the 0th day, indicating that the preservation effect of composite preservative glaze is significantly better than the existing preservation technology. According to Figure 8 The results show that compared with the treatment without glaze, the composite preservative immersion method has less effect on the change of TBA value, while the glaze technology can further reduce the TBA value of fish meat, among which the composite preservative combined with glaze has a more significant effect. From the 0th day to the 12th day, the TBA value of the pure water glaze treatment group increased by about 68.6%, and the TBA value of the composite preservative glaze treatment group increased by 39.2%, indicating that compared with the existing preservation technology, the composite preservative glaze method can more effectively inhibit the rate of fat oxidation and improve the flavor and quality of Spanish mackerel meat.

[0104] In summary, the method of using composite preservatives to coat fish meat with ice can more effectively regulate the pH value and water activity of fish meat than the existing preservation technology, avoid the decomposition of specific flavor amino acids such as glutamic acid and aspartic acid, further delay the spoilage process of fish meat, and also delay the conformational changes of myofibrillar proteins in fish meat, thereby maintaining the hardness, protein content and quality of fish meat.

[0105] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A composite preservative, characterized in that: Including trehalose, tea polyphenols and vitamin E.

2. The composite preservative according to claim 1, characterized in that: It includes 0.1-1% trehalose, 0.05-0.35% tea polyphenols and 0.05-0.35% vitamin E.

3. A method for preserving Spanish mackerel, characterized in that: The composite preservative as claimed in any one of claims 1 to 2 is used to preserve Spanish mackerel.

4. The preservation method according to claim 3, characterized in that: The mackerel pieces are firstly soaked in ozone water for sterilization, and then a composite preservative is used to coat the surface of the fish pieces with an ice coating for preservation.

5. The preservation method according to claim 4, characterized in that: The concentration of the ozone water is 0-4 mg / L, and the soaking time is 0-12 min.

6. The preservation method according to claim 5, characterized in that: The following steps are involved: (1) Pretreatment: slicing, marinating, roasting, cooling, and cutting the mackerel; (2) Sterilization treatment: soak the fish pieces obtained in step (1) in ozone water for 8 to 12 minutes and then remove them; (3) Ice coating treatment: the fish block obtained in step (2) is quickly frozen at low temperature, and after freezing, it is placed in a composite preservative and soaked for 5 to 10 minutes, then taken out and frozen, and the operation is repeated until a 1 to 2 cm ice coating is formed on the surface of the fish block; (4) Low temperature treatment: The mackerel pieces obtained in step (3) are vacuum packed and then stored.

7. The preservation method according to claim 6, characterized in that: In the step (2), the temperature of the ozone water is 0-20° C., and the liquid-to-material ratio of the ozone water to the mackerel pieces is (3-10):

1.

8. Use of a composition for preparing a preservative for inhibiting the growth of microorganisms in fish meat, characterized in that: The composition comprises 0.1-1% trehalose, 0.05-0.35% tea polyphenols and 0.05-0.35% vitamin E.

9. Use of a composition for preparing a preservative for improving the antioxidant effect of fish, characterized in that: The composition comprises 0.1-1% trehalose, 0.05-0.35% tea polyphenols and 0.05-0.35% vitamin E.

10. The use according to claim 9, characterized in that The fish meat is mackerel.

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