Composite preservative for refrigerated sea bass fillets and comprehensive freshness and quality preservation method thereof

Abstract

The present invention discloses a composite preservative for refrigerated sea bass fillets and a comprehensive fresh-keeping and quality preservation method thereof. The raw materials of the composite preservative include 1-5% trehalose, 0.1-0.5% sodium citrate, 0.03-0.09% ginger extract, 0.3-0.9% D-sodium isoascorbate, 0.03-0.09% nisin, and 0.01-0.03% ε-polylysine in terms of mass percentage; the balance is water. The fresh-keeping and quality preservation method consists of the following steps: preparing and pre-cooling the composite preservative; soaking the treated sea bass fillets in the pre-cooled composite preservative; finally, draining the soaked sea bass fillets and bagging them, and then refrigerating them. The raw materials of the composite preservative of the present invention are natural, green and environmentally friendly, have good fresh-keeping and quality preservation effects, can extend the shelf life of refrigerated California sea bass fillets, and have an inhibitory effect on the oxidation of myofibrillar protein.

Description

Technical Field

[0001] The invention relates to the technical field of aquatic product freshness preservation and quality maintenance and processing, and in particular to a composite preservative for refrigerated sea bass fillets and a comprehensive freshness preservation and quality maintenance method thereof. Background Art

[0002] California bass (Micropterus salmoides), also known as largemouth bass, is native to the freshwater basins of California, USA. It is one of the freshwater fish species introduced for aquaculture in my country. It has high edible and nutritional value, and a relatively moderate market price, making it suitable for general household consumption. Its aquaculture scale and production are increasing annually, showing considerable market potential and advantages. In my country, California bass is a typical freshwater fish species sold at the place of production and distributed nationwide. Its sales form is mainly fresh products. However, there are still few products and research on the preservation and deep processing of California bass. This has led to a mismatch between the preservation and deep processing technology and the level of aquaculture in my country. With the rise of the prepared meal industry in recent years, to better meet market demand, some existing aquaculture companies have gradually shifted from the traditional live fresh aquaculture business model to the development of highly processed products. Therefore, the sales model of slaughtering, processing, packaging, and preserving California bass through the cold chain will be the future development trend of fish products. The meat of California bass is rich in protein and unsaturated fatty acids. It is easily hydrolyzed and oxidized by microorganisms and endogenous enzymes at room temperature, which adversely affects the freshness of the fish.

[0003] In the existing technology, the preservation technology of aquatic products mainly includes chemical preservation technology and low-temperature preservation technology. Chemical preservation technology has certain hazards to human health; low-temperature preservation technology can appropriately extend the shelf life of fish meat. At the same time, refrigerated preservation has little effect on product quality and can avoid muscle structure damage and thawing loss caused by freezing. However, the storage period of refrigerated fish meat is relatively short, generally about 7 days, and the water retention, texture and other qualities of California bass will also decline with the extension of storage time. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of existing technologies and provides a composite preservative for refrigerated sea bass fillets and a comprehensive preservation method thereof. By combining low-temperature preservation technology with biological preservation technology, the invention utilizes the water-retaining and fresh-keeping properties of trehalose and sodium citrate, the antibacterial properties of nisin and ε-polylysine, and the antioxidant activity of sodium D-isoascorbate and phenolic compounds in ginger extract to soak California sea bass fillets, thereby extending the shelf life of refrigerated California sea bass while preserving its quality, protein structure, water-retention properties, and oxidative stability to the greatest extent possible.

[0005] To achieve the above objectives, the present invention provides a composite preservative for refrigerated sea bass fillets. The raw materials of the composite preservative include, by mass percentage, 1-5% trehalose, 0.1-0.5% sodium citrate, 0.03-0.09% ginger extract, 0.3-0.9% sodium D-isoascorbate, 0.03-0.09% nisin, and 0.01-0.03% ε-polylysine; the balance is water.

[0006] Preferably, the raw materials of the composite preservative include, by mass percentage, 2-4% trehalose, 0.2-0.3% sodium citrate, 0.04-0.08% ginger extract, 0.4-0.8% sodium D-isoascorbate, 0.04-0.08% nisin, and 0.01-0.03% ε-polylysine; the balance is water.

[0007] Preferably, the raw materials of the composite preservative include, by mass percentage, 3% trehalose, 0.3% sodium citrate, 0.06% ginger extract, 0.6% sodium D-isoascorbate, 0.06% nisin, and 0.02% ε-polylysine; the balance is water.

[0008] Preferably, the water is sterile water.

[0009] The present invention also provides a comprehensive fresh-keeping and quality preservation method for refrigerated sea bass fillets, comprising the following steps:

[0010] (1) Slaughter fresh sea bass, remove scales, internal organs, head and tail, cut the fish meat on both sides along the spine, wash and slice to obtain sea bass fillets;

[0011] (2) soaking the sea bass fillets processed in step (1) in the compound preservative according to claim 1;

[0012] (3) draining the sea bass fillets soaked in step (2), bagging them, and then refrigerating them.

[0013] Preferably, in step (2), the prepared compound preservative is pre-cooled before adding the sea bass fillets.

[0014] Preferably, the pre-cooling temperature is 4±1°C.

[0015] Preferably, in step (2), the material-liquid ratio of sea bass fillet to compound preservative is 1:2-4 (g / mL).

[0016] Preferably, the soaking time of the sea bass fillets in step (3) is 30 minutes.

[0017] Preferably, the refrigeration temperature in step (3) is 4±1°C.

[0018] Beneficial effects of the present invention:

[0019] 1. The composite preservative of the present invention has natural, green, and environmentally friendly raw materials, is safer for human health, has excellent freshness and quality preservation effects, can extend the shelf life of refrigerated California sea bass fillets, and has an inhibitory effect on the oxidation of myofibrillar protein. Among them, the sample group treated with 3% (mass fraction, the same below) trehalose, 0.3% sodium citrate, 0.06% ginger extract, 0.6% sodium D-isoascorbate, 0.06% nisin, and 0.02% ε-polylysine showed the best overall quality characteristics and protein structure, water retention, and oxidative stability, and the best water retention and freshness preservation effects.

[0020] 2. The compound preservative treatment groups of the present invention were able to inhibit the growth of microorganisms in California sea bass and slow the increase in the volatile basic nitrogen content and pH value of the fish meat. The compound preservative treatment groups also had a positive effect on the water retention of California sea bass, improving its water holding capacity and inhibiting the loss of moisture in the meat.

[0021] 3. The compound preservative treatment group of the present invention can inhibit the oxidative denaturation of California sea bass myofibrillar protein during cold storage. The compound preservative treatment group can slow down the total sulfhydryl content and Ca 2+ -Decrease in ATPase activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The effects of different embodiments of the present invention on the total bacterial count of refrigerated California sea bass are shown;

[0023] Figure 2 The effects of different embodiments of the present invention on the pH of refrigerated California sea bass are shown;

[0024] Figure 3 The effects of different embodiments of the present invention on the TVB-N content of refrigerated California sea bass are shown;

[0025] Figure 4 The effects of different embodiments of the present invention on the moisture content of refrigerated California sea bass are shown;

[0026] Figure 5 The effects of different embodiments of the present invention on the total sulfhydryl content of refrigerated California sea bass protein are shown;

[0027] Figure 6 Different embodiments of the present invention are used to refrigerate California sea bass Ca 2+ -Effects on ATPase. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0029] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0030] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0032] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] The raw materials of the composite preservative 1 include, by mass percentage, 1% trehalose, 0.1% sodium citrate, 0.03% ginger extract, 0.3% sodium D-isoascorbate, 0.03% nisin, and 0.01% epsilon-polylysine; the balance is water.

[0036] Among them, the preparation of ginger extract: fresh ginger is washed, drained, sliced, and placed in an electric drying oven at 65-75°C to dry to constant weight. The dried ginger slices are crushed with a grinder and passed through a 40-mesh sieve. A certain amount of ginger powder is weighed, 75% ethanol is added according to a solid-liquid ratio of 1:15 (g / mL), and a magnetic stirrer is used to maintain magnetic stirring at 80°C for 2.5 hours. The filtrate is filtered under reduced pressure to obtain a filtrate. The filter residue is extracted once according to the above method, the two filtrates are combined, and the ethanol is removed using a rotary evaporator to obtain a paste without ethanol odor, which is the ginger extract.

[0037] Quality Control Method for Ginger Extract: The quality of ginger extract is controlled by measuring the total phenolic content. Accurately pipette 0.5 mL of the diluted ginger extract solution (1 mg / mL) into a 50 mL volumetric flask, add 2.5 mL of Folin-phenol reagent, shake well, and let stand for 5 minutes. Then, add 5 mL of 10% Na₂CO₃, shake well, bring to volume, and let stand in the dark for 30 minutes. Measure the absorbance at 765 nm. Repeat three times and take the average value. Calculate the total phenolic concentration of the sample using a standard working curve plotted with gallic acid (GA). The result is expressed as mg GA / g of ginger extract.

[0038] Example 2

[0039] The raw materials of the composite preservative 2 include, by mass percentage, 3% trehalose, 0.3% sodium citrate, 0.06% ginger extract, 0.6% sodium D-isoascorbate, 0.06% nisin, and 0.02% ε-polylysine; the balance is water.

[0040] The preparation and quality control methods of the ginger extract are the same as those in Example 1.

[0041] Example 3

[0042] The raw materials of the composite preservative 3 include, by mass percentage, 5% trehalose, 0.5% sodium citrate, 0.09% ginger extract, 0.9% sodium D-isoascorbate, 0.09% nisin, and 0.03% ε-polylysine; the balance is water.

[0043] The preparation and quality control methods of the ginger extract are the same as those in Example 1.

[0044] Example 4

[0045] The raw materials of the composite preservative 4 include, by mass percentage, 2% trehalose, 0.2% sodium citrate, 0.04% ginger extract, 0.4% sodium D-isoascorbate, 0.04% nisin, and 0.01% ε-polylysine; the balance is water.

[0046] The preparation and quality control methods of the ginger extract are the same as those in Example 1.

[0047] Example 5

[0048] The raw materials of the composite preservative 5 include, by mass percentage, 4% trehalose, 0.3% sodium citrate, 0.08% ginger extract, 0.8% sodium D-isoascorbate, 0.08% nisin, and 0.03% ε-polylysine; the balance is water.

[0049] The preparation and quality control methods of the ginger extract are the same as those in Example 1.

[0050] Example 6

[0051] A comprehensive method for preserving and maintaining the quality of refrigerated sea bass fillets comprises the following steps:

[0052] (1) Kill fresh sea bass, remove the scales, internal organs, head and tail, cut the fish meat on both sides along the spine, wash and slice;

[0053] (2) Precooling the composite preservative 1 prepared in Example 1 to 4±1° C., and soaking the sea bass fillets treated in step (1) in the precooled composite preservative at a material-liquid ratio of 1:2 (g / mL) for 30 minutes;

[0054] (3) Drain the sea bass fillets processed in step (2) and bag them, then place them in a refrigerator or freezer at 4±1°C for refrigeration.

[0055] Example 7

[0056] A comprehensive method for preserving and maintaining the quality of refrigerated sea bass fillets comprises the following steps:

[0057] (1) Kill fresh sea bass, remove the scales, internal organs, head and tail, cut the fish meat on both sides along the spine, wash and slice;

[0058] (2) Precooling the composite preservative 2 prepared in Example 2 to 4±1° C., and soaking the sea bass fillets treated in step (1) in the precooled composite preservative at a material-liquid ratio of 1:3 (g / mL) for 30 minutes;

[0059] (3) Drain the sea bass fillets processed in step (2) and bag them, then place them in a refrigerator or freezer at 4±1°C for refrigeration.

[0060] Example 8

[0061] A comprehensive method for preserving and maintaining the quality of refrigerated sea bass fillets comprises the following steps:

[0062] (1) Kill fresh sea bass, remove the scales, internal organs, head and tail, cut the fish meat on both sides along the spine, wash and slice;

[0063] (2) Precooling the composite preservative 3 prepared in Example 3 to 4±1° C., and soaking the sea bass fillets treated in step (1) in the precooled composite preservative at a material-liquid ratio of 1:4 (g / mL) for 30 min;

[0064] (3) Drain the sea bass fillets processed in step (3) and bag them, then place them in a refrigerator or freezer at 4±1°C for refrigeration.

[0065] Comparative Example 1

[0066] (1) Kill fresh sea bass, remove the scales, internal organs, head and tail, cut the fish meat on both sides along the spine, wash and slice;

[0067] (2) Pre-cool sterile water in a refrigerator or freezer at 4±1℃;

[0068] (3) Soaking the sea bass fillets treated in step (1) in the sterile water described in step (2) at a material-liquid ratio of 1:3 (g / mL) for 30 minutes;

[0069] (4) Drain the sea bass fillets processed in step (3) and bag them, then place them in a refrigerator or freezer at 4±1°C for refrigeration.

[0070] Effect test

[0071] The sea bass treated in Examples 6 to 8 and Comparative Example 1 were subjected to quality indices (total colony count, pH value, volatile basic nitrogen, moisture content) and protein indices (total sulfhydryl content, Ca 2+ -ATPase activity) was measured, and the results were expressed as the average of three measurements.

[0072] Determination of Total Colony Count: Determine the total colony count in the sample with reference to GB / T 4789.2-2022, "National Food Safety Standard - Microbiological Testing of Foods - Determination of Total Colony Count." Place 5.00g of fish meat in a sterile bag containing 45mL of sterile saline solution. Thoroughly pat the homogenate, then perform a 10-fold serial dilution. Select 1 to 3 samples of appropriate dilutions and pipette 1mL of each into sterile Petri dishes. Add plate count agar medium and mix thoroughly. After appropriate placement, invert the plate and incubate at 36°C ± 1°C for 72h ± 3h. The results are expressed as 1g (CFU / g).

[0073] pH value determination method: refer to GB 5009.237-2016 "National Food Safety Standard - Determination of pH Value of Food" to determine the pH value of fish meat, and measure each group of samples in parallel three times.

[0074] Determination of total volatile base nitrogen (TVB-N): The TVB-N content in fish meat was determined according to the semi-micro nitrogen determination method in GB5009.228-2016 "National Food Safety Standard - Determination of Volatile Basic Nitrogen in Foods", and each group of samples was measured in parallel three times.

[0075] Table 1 Determination results of total colony count, pH value and TVB-N content in fish meat

[0076]

[0077] According to GB 18406.4-2001 "Safety and Quality of Agricultural Products and Safety Requirements for Pollution-free Aquatic Products", the total number of colonies in the microbial index should be ≤10 6 According to GB 2733-2015 "Fresh and Frozen Aquatic Products of Animal Origin", the TVB-N content of freshwater fish should be ≤20mg / 100g.

[0078] As shown in Table 1, by the 12th day of refrigerated storage, the total bacterial count and volatile basic nitrogen content of Examples 6-8, using the treatment method of the present invention, were within the national safety range, and the pH of the fish meat was within the appropriate range. The total bacterial count of the fish meat in Comparative Example 1 exceeded the prescribed microbial limit by the 12th day, the TVB-N content exceeded the spoilage limit by the 16th day, and the pH value increased. The method described in the present invention can effectively inhibit the growth of microorganisms in refrigerated sea bass fillets, delay the breakdown of protein in the fish meat into nitrogen-containing substances such as trimethylamine, and extend the shelf life of the fish meat by up to 12 days.

[0079] Determination of moisture content: The moisture content of fish meat was determined by the direct drying method in accordance with GB 5009.3-2016 National Food Safety Standard - Determination of Moisture in Foods. Each group of samples was measured three times in parallel.

[0080] Table 2 Determination results of water content in fish meat

[0081]

[0082] As can be seen from Table 2, the moisture content of the fish meat treated with the composite preservatives 1 to 3 of Examples 1 to 3 combined with the treatment methods of Examples 6 to 8 during refrigeration is higher than that of Comparative Example 1, indicating that the method of the present invention can effectively inhibit the loss of moisture content in refrigerated sea bass fillets and improve the water retention of the fish meat.

[0083] Determination of total thiol content: Prepare a 2 mg / mL myofibrillar protein solution. Take 0.5 mL of myofibrillar protein solution and add it to 4.5 mL of Tris-glycine-urea buffer (1% Tris, 92 mmol / L glycine, 4 mmol / L E-DTA, 8 mol / L urea, pH = 8.0). Vortex thoroughly, add 0.2 mL of Ellman's reagent, and react at 25°C for 30 minutes. Measure the absorbance at 412 nm. Use 0.02 mol / L phosphate buffer (containing 0.6 mol / L NaCl, pH = 7.0) as a blank control. Calculate the total thiol content of MP in μmol / g protein.

[0084] Ca 2+ -ATPase activity assay: Accurately weigh fish meat and add physiological saline at a mass-to-volume ratio of 1:9 (g / mL). Homogenize under ice-water bath conditions, centrifuge at 10,000 rpm for 10 min, dilute the supernatant 10 times to obtain the sample solution, and determine the tissue protein concentration by the biuret method. The subsequent operation steps refer to the ultra-micro ATPase (Ca 2+ -ATPase) detection kit instructions, Ca 2+ -ATPase activity results were expressed as U / mg protein.

[0085] Table 3 Total sulfhydryl content, Ca in fish protein 2+ -ATPase activity measurement results

[0086]

[0087] The decrease in total thiol content indicates that the free active thiol groups in fish protein undergo oxidation reaction to form disulfide bonds, resulting in a decrease in total thiol content; Ca 2+ -The lower the ATPase activity, the more serious the damage to the myosin structure in fish protein.

[0088] As shown in Table 3, the total sulfhydryl content and Ca content of fish protein in Examples 6 to 8 using the treatment method of the present invention during refrigeration are 2+ -ATPase activity was higher than that of comparative example 1, indicating that the method of the present invention can effectively inhibit the oxidation of refrigerated sea bass fillet protein and has a certain protective effect on the protein structure.

[0089] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application 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 make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A comprehensive fresh-keeping and quality-preserving method for refrigerated sea bass fillets, characterized in that: The following steps are involved: (1) Kill fresh sea bass, remove the scales, internal organs, head and tail, cut the fish meat on both sides along the spine, wash and slice to obtain sea bass fillets; (2) Prepare a composite preservative, wherein the raw materials of the composite preservative include 3% trehalose, 0.3% sodium citrate, 0.06% ginger extract, 0.6% sodium D-isoascorbate, 0.06% nisin, 0.02% ε-polylysine, and the balance is water; pre-cool the composite preservative, the pre-cooling temperature is 4±1°C, and the sea bass slices treated in step (1) are immersed in the composite preservative, and the material-liquid ratio of the sea bass slices to the composite preservative is 1:2~4g / mL; the preparation method of the ginger extract is as follows: wash, drain, and slice fresh ginger, and place it in an electric drying oven at 65-75°C to dry to constant weight; grind the dried ginger slices with a grinder and pass through a 40-mesh sieve; weigh a certain amount of ginger powder, add 75% ethanol according to a material-liquid ratio of 1:15g / mL, and use a magnetic stirrer to maintain 80 The mixture was extracted under magnetic stirring for 2.5 h, and the filtrate was obtained by vacuum filtration. The residue was extracted once again according to the above method. The two filtrates were combined and the ethanol was removed by rotary evaporation to obtain a paste without ethanol odor, which is the ginger extract. (3) Drain the sea bass fillets soaked in step (2), bag them, and then refrigerate them.

2. The comprehensive fresh-keeping and quality-preserving method for refrigerated sea bass fillets according to claim 1, characterized in that: The water in step (2) is sterile water.

3. The comprehensive fresh-keeping and quality-preserving method for refrigerated sea bass fillets according to claim 1, characterized in that: The soaking time of the sea bass fillets in step (3) is 30 min.

4. The comprehensive fresh-keeping and quality-preserving method for refrigerated sea bass fillets according to claim 1, characterized in that: The refrigeration temperature in step (3) is 4±1°C.

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