Fresh pseudosciaena crocea bacteriostasis and preservation method based on hydroxyl free radicals

Abstract

The invention discloses a hydroxyl radical-based fresh pseudosciaena crocea bacteriostasis and preservation method, which comprises the following steps: removing heads, fins and scales from fresh pseudosciaena crocea, cleaning, putting the treated fresh pseudosciaena crocea in water, starting a hydroxyl radical generation device, and soaking; and fishing out, soaking in a thymol solution with the concentration of 100mg / L, fishing out, removing surface moisture by using absorbent paper, and refrigerating in a refrigerator at 4-8 DEG C. Growth and reproduction of microorganisms in the large yellow croaker in the storage process can be effectively controlled, so that decay of the large yellow croaker is delayed, protein denaturation degradation and fat oxidation in the storage process of the large yellow croaker can be controlled, myofibrillar protein of the large yellow croaker is not damaged, and the edible taste of the large yellow croaker is kept; meanwhile, no chemical residue is left in the storage process.

Description

Technical Field

[0001] The invention relates to the technical field of food, and in particular to a hydroxyl free radical-based antibacterial and fresh-keeping method for fresh large yellow croaker. Background Art

[0002] Yellow croaker is a fish of the order Perciformes, family Sciaenidae, order Yellow croaker, also known as yellow croaker, yellow croaker, big fresh, cucumber, and one of the four traditional marine fishery species in China. It is a precious edible economic fish. Yellow croaker meat is delicate and rich in high-quality protein. Every 100 grams of yellow croaker meat contains about 17.6 grams to 22.4 grams of protein. The amino acid composition in the body of yellow croaker is higher than the FAO / WHO ideal model evaluation standard, and the amino acid types are complete, including but not limited to lysine, tryptophan, phenylalanine, methionine, threonine, isoleucine, leucine and valine. In addition, yellow croaker is also rich in unsaturated fatty acids. Studies have shown that the content of EPA+DHA is as high as 18.39%, which has a significant effect on lowering blood cholesterol levels and preventing cardiovascular diseases. In addition to protein and fatty acids, large yellow croaker is also a good source of vitamins and minerals. It is rich in vitamin A, which is essential for maintaining healthy vision and enhancing immunity. At the same time, it also contains B vitamins, which play an important role in energy metabolism, nervous system function and cardiovascular health. In addition, mineral elements such as calcium, phosphorus and potassium in large yellow croaker are also essential for the human body and are important for maintaining bone health and regulating water and electrolyte balance.

[0003] Studies have found that the main mechanisms of yellow croaker spoilage are microbial action, oxidation and enzyme action. Farmed yellow croaker has a high fat content, and unsaturated fatty acids are easily oxidized. After leaving the seawater environment and dying, a series of biochemical reactions occur under the action of endogenous enzymes and microorganisms, resulting in four stages of rigor mortis, thawing, autolysis and corruption. These factors affect the quality changes of yellow croaker during processing, transportation and storage, making the fish meat difficult to be accepted by consumers, with an unpleasant odor, and eventually completely losing its use value. At present, the main forms of preservation of yellow croaker are low-temperature refrigeration and low-temperature freezing, and it is often circulated as frozen products in the market. However, cold storage can only inhibit the growth of microorganisms to a certain extent, thereby inhibiting the corruption of yellow croaker, and cannot effectively inhibit the microorganisms in and on the surface of yellow croaker, and the preservation effect is poor; the ice crystals formed during the freezing process will inevitably damage the muscle tissue of yellow croaker, causing the muscle tissue to lose water and soften, affecting the taste of yellow croaker and reducing its edible value. In addition to freezing and chilling methods, there are also controlled atmosphere preservation and coating preservation methods, all of which have disadvantages such as high cost, low efficiency, and easy presence of chemical residues.

[0004] In summary, other technologies are needed during the storage process of large yellow croaker to effectively control the growth of microorganisms and to control protein denaturation and degradation and fat oxidation as much as possible during the storage process of large yellow croaker, while leaving no harmful chemical residues. Summary of the invention

[0005] [Technical issues]

[0006] The invention aims to solve the problem of how to inhibit the growth and reproduction of spoilage bacteria during the storage of large yellow croaker so as to delay the spoilage of large yellow croaker, and secondly to prevent the loss of nutrients of large yellow croaker during the storage process to a greater extent.

[0007] [Technical solution]

[0008] In view of the above problems existing in the prior art, the present invention provides a method for antibacterial preservation of fresh large yellow croaker based on hydroxyl free radicals. The present invention treats large yellow croaker with hydroxyl free radical water and then soaks the large yellow croaker with thymol solution, which can effectively control the growth and reproduction of microorganisms in the large yellow croaker during storage, and refrigeration at 4°C can also control protein denaturation and degradation and fat oxidation during storage of large yellow croaker, and no chemical residue is left during storage.

[0009] The technical solution of the present invention is as follows:

[0010] The first object of the present invention is to provide a method for antibacterial preservation of fresh large yellow croaker based on hydroxyl radicals, comprising the following steps:

[0011] Remove the head, fins and scales of fresh yellow croaker, clean it, and then soak it in water equipped with a hydroxyl free radical generator; take it out and soak it in thymol solution again, then take it out to remove surface moisture and refrigerate it.

[0012] In one embodiment of the present invention, water containing hydroxyl radicals is prepared using a hydroxyl radical generating device.

[0013] In one embodiment of the present invention, after the processed fresh large yellow croaker is placed in water, a hydroxyl radical generating device is turned on to weaken the quenching of hydroxyl radicals.

[0014] In one embodiment of the present invention, the pH value of the water containing hydroxyl radicals is 5.87-6.92.

[0015] In one embodiment of the present invention, the immersion in water containing hydroxyl radicals is performed for 8-12 minutes.

[0016] In one embodiment of the present invention, the sample is immersed in water containing hydroxyl radicals for 10 minutes.

[0017] In one embodiment of the present invention, the concentration of the thymol solution is 100 mg / L.

[0018] In one embodiment of the present invention, the soaking in the thymol solution is for 3-7 minutes.

[0019] In one embodiment of the present invention, the soaking in the thymol solution is for 4-6 minutes.

[0020] In one embodiment of the present invention, absorbent paper is used to remove moisture from the surface of large yellow croaker.

[0021] In one embodiment of the present invention, the refrigeration temperature is 4-8°C.

[0022] The beneficial technical effects of the present invention are:

[0023] The hydroxyl radicals of the present invention have strong oxidizing properties, can effectively kill bacteria and viruses, degrade organic matter, can effectively remove spoilage bacteria on the surface and inside of large yellow croaker, prevent large-scale reproduction of microorganisms during storage to accelerate the corruption of large yellow croaker, extend the shelf life of large yellow croaker, and can be used in the field of food preservation. Thymol can neutralize the remaining hydroxyl radicals and weaken the oxidative effect of hydroxyl radicals on nutrients in large yellow croaker.

[0024] The invention can significantly prolong the storage time of large yellow croaker meat at 4°C and prolong the shelf life, and can inhibit the growth of spoilage bacteria in large yellow croaker while preventing ice crystals from forming in large yellow croaker during frozen storage to damage the muscle tissue of large yellow croaker, causing the muscle tissue to lose water and soften, thereby affecting the edible taste of large yellow croaker and reducing the edible value.

[0025] At the same time, it avoids the phenomenon that the existing common freezing technology aggravates the breakage of yellow croaker muscle fibers and affects the edible quality of yellow croaker, and also avoids the shortcomings of other processing technologies such as low sterilization efficiency and easy to leave chemical residues.

[0026] The invention can effectively extend the shelf life of large yellow croaker by about 6 days, effectively slow down fat oxidation and protein degradation during storage of large yellow croaker, and reduce nutrient loss during storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The total number of colonies during storage of Examples 1-5 and Comparative Examples 1-6 is changed;

[0028] Figure 2 The TVB-N value changes during storage of Examples 1-5 and Comparative Examples 1-6;

[0029] Figure 3 The total thiol content changes during storage of Examples 1-5 and Comparative Examples 1-6;

[0030] Figure 4 The TBARs value changes during storage of Examples 1-5 and Comparative Examples 1-6. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0032] Determination of total bacterial count during storage of large yellow croaker:

[0033] Weigh the large yellow croaker meat aseptically, take 10g of the fish meat and add it to 90mL of sterilized physiological saline, homogenize it with a homogenizer for 1min, dilute the homogenized suspension continuously according to the gradient (1:10), take 100μL of each sample and add it to a sterile culture dish of PCA solid medium. Incubate in a 30℃ incubator for 24 hours. Determine the total viable count (log(CFU / mL)) by the plate count method.

[0034] TVB-N determination:

[0035] Take 20g of fish meat and add 100mL of water to soak for 30min, then filter. Apply water-soluble glue to the edge of the diffusion dish, add 1mL of boric acid solution and 1 drop of mixing indicator to the center chamber of the dish. Accurately add 1.0mL of filtrate to the outer chamber of the dish, cover with frosted glass cover, and then quickly add 1mL of saturated potassium carbonate solution from the gap, immediately push the frosted glass cover horizontally to fully mix the sample solution and saturated potassium carbonate solution, then place in a 37℃±1℃ incubator for 2h, cool to room temperature, and titrate with hydrochloric acid or sulfuric acid standard titration solution (0.0100mol / L).

[0036]

[0037] Where: V1 is the volume of hydrochloric acid or sulfuric acid standard titration solution consumed by the test solution, in milliliters (mL); V2 is the volume of hydrochloric acid or sulfuric acid standard titration solution consumed by the reagent blank, in milliliters (mL); c is the concentration of hydrochloric acid or sulfuric acid standard titration solution, in moles per liter (mol / L); I4 is the concentration of 1.0 mL of hydrochloric acid [c(HCl) = 1.000 mol / L] or sulfuric acid [c(1 / H 2 SO 4 )=1.000mol / L] The mass of nitrogen equivalent to the standard titration solution, in grams per mole (g / mol); m is the mass of the sample, in grams (g), or the volume of the sample, in milliliters (mL); V is the volume of the filtrate accurately drawn, in milliliters (mL). In this method, V=1; V 0 is the total volume of the sample solution, in milliliters (mL). In this method, V 0 =100; 100 is the conversion factor for converting the calculated result into milligrams per hundred grams (mg / 100g).

[0038] Determination of total thiol content:

[0039] The total thiol content of large yellow croaker was determined using a total thiol content detection kit manufactured by Solebold, and the specific operation was carried out according to the instructions.

[0040] TBARs value determination:

[0041] The malondialdehyde standard was diluted into standard solutions of different concentrations. 500 μL of malondialdehyde solution was mixed with 500 μL of 0.02 mol / L TBA solution, and the mixture was placed in a boiling water bath for 20 min. The absorbance of the sample at 532 nm was measured using an enzyme marker, and the standard curve was determined based on the calculated values.

[0042] Take 2g of fish meat, add 10mL5% trichloroacetic acid, filter, and centrifuge the filtrate (8000rpm, 10min, 4°C). After centrifugation, take 500μL of supernatant and mix it with 500μL of 0.02mol / L TBA solution. Boil the mixture in a boiling water bath for 20min, measure the absorbance of the sample at 532nm with an enzyme marker, and calculate the malondialdehyde content in the sample according to the standard curve.

[0043] Example 1

[0044] Remove the head, fins and scales of fresh yellow croaker, and then clean it. After placing the processed fresh yellow croaker in water, turn on the hydroxyl free radical generating device and soak it for 10 minutes (the pH value of water containing hydroxyl free radicals is 6.25-6.41); after taking it out, soak it in a thymol solution with a concentration of 100 mg / L for 5 minutes, then take it out and remove the surface moisture with absorbent paper and put it into a 4°C refrigerator for refrigeration.

[0045] Example 2

[0046] Remove the head, fins and scales of fresh yellow croaker, and then clean it. After placing the processed fresh yellow croaker in water, turn on the hydroxyl free radical generating device and soak it for 10 minutes (the pH value of water containing hydroxyl free radicals is 6.25-6.41); after taking it out, soak it in a thymol solution with a concentration of 100 mg / L for 4 minutes, then take it out and remove the surface moisture with absorbent paper and put it into a 4°C refrigerator for refrigeration.

[0047] Example 3

[0048] Remove the head, fins and scales of fresh yellow croaker, and then clean it. After placing the processed fresh yellow croaker in water, turn on the hydroxyl free radical generating device and soak it for 10 minutes (the pH value of water containing hydroxyl free radicals is 6.25-6.41); after taking it out, soak it in a thymol solution with a concentration of 100 mg / L for 6 minutes, then take it out and remove the surface moisture with absorbent paper and put it into a 4°C refrigerator for refrigeration.

[0049] Example 4

[0050] Remove the head, fins and scales of fresh yellow croaker and clean it. Place the processed fresh yellow croaker in water, turn on the hydroxyl radical generating device, and soak it for 8 minutes (the pH value of water containing hydroxyl free radicals is 6.73-6.92); take it out and soak it in a thymol solution with a concentration of 100 mg / L for 6 minutes, then take it out and remove the surface moisture with absorbent paper and put it into a 5°C refrigerator for refrigeration.

[0051] Example 5

[0052] Remove the head, fins and scales of fresh yellow croaker, and then clean it. After placing the processed fresh yellow croaker in water, turn on the hydroxyl radical generating device and soak it for 12 minutes (the pH value of water containing hydroxyl free radicals is 5.87-6.04); after taking it out, soak it in a thymol solution with a concentration of 100 mg / L for 4 minutes, then take it out and remove the surface moisture with absorbent paper and put it into a 6°C refrigerator for refrigeration.

[0053] Comparative Example 1

[0054] Remove the head, fins and scales of fresh yellow croaker, wash and set aside. Use absorbent paper to absorb the surface moisture of the processed yellow croaker and refrigerate it in a 4℃ refrigerator.

[0055] Comparative Example 2

[0056] Remove the head, fins and scales of fresh yellow croaker, wash and set aside. Soak the processed yellow croaker in water, turn on the hydroxyl free radical generating device, and soak for 10 minutes (the pH value of water containing hydroxyl free radicals is 6.25-6.41). Take out the yellow croaker, absorb the surface moisture with absorbent paper, and put it into a 4°C refrigerator.

[0057] Comparative Example 3

[0058] Remove the head, fins and scales of fresh yellow croaker, wash and set aside. Soak the processed yellow croaker in water, turn on the hydroxyl free radical generating device, and soak for 5 minutes (the pH value of water containing hydroxyl free radicals is 7.05-7.13). Take out the yellow croaker, absorb the surface moisture with absorbent paper, and put it into a 4°C refrigerator.

[0059] Comparative Example 4

[0060] Remove the head, fins and scales of fresh yellow croaker, wash and set aside; place the processed fresh yellow croaker in water, turn on the hydroxyl radical generating device, and soak for 15 minutes (the pH value of water containing hydroxyl free radicals is 5.74-5.85); take out the yellow croaker, absorb the surface moisture with absorbent paper, and put it into a 4°C refrigerator for refrigeration.

[0061] Comparative Example 5

[0062] Remove the head, fins and scales of fresh yellow croaker, wash and set aside, soak the processed yellow croaker in water, turn on the hydroxyl free radical generating device, soak for 8 minutes (the pH value of water containing hydroxyl free radicals is 6.73-6.92), take out the yellow croaker, absorb the surface moisture with absorbent paper, and put it into a 4°C refrigerator.

[0063] Comparative Example 6

[0064] Remove the head, fins and scales of fresh yellow croaker, wash and set aside, soak the processed yellow croaker in water, turn on the hydroxyl free radical generating device, soak for 12 minutes (the pH value of water containing hydroxyl free radicals is 5.87-6.04), take out the yellow croaker, absorb the surface moisture with absorbent paper and put it into a 4°C refrigerator.

[0065] The results are as follows:

[0066] Changes in total colony count:

[0067] Figure 1 The total number of colonies during storage of Examples 1-5 and Comparative Examples 1-6 is shown in the figure; as can be seen from the figure, the total number of colonies in the samples of Comparative Examples 1 and 3 is higher than that of the other groups at the beginning and end of storage, and the growth and reproduction rate of the colonies is relatively fast, and the total number of colonies in Comparative Examples 2, Comparative Examples 4-6 and Examples 1-5 is relatively low, indicating that hydroxyl radical treatment can effectively kill the spoilage bacteria in the large yellow croaker and can effectively inhibit the growth of bacteria. There is no significant difference in the total number of colonies between Examples 1-3 and Comparative Example 2 (P>0.1), indicating that immersion in 100 mg / L concentration of thymol has no significant effect on the killing of spoilage bacteria on the surface and in the large yellow croaker.

[0068] TVB-N value changes:

[0069] Volatile basic nitrogen (TVB-N) is the main indicator of the freshness of raw fish and meat. Aquatic products with a TVB-N value lower than 13 mg / 100g are of first-class freshness, which means they are highly fresh. According to EU Commission Directive No. 1022 / 2008, the acceptable limit of TVB-N value is 30 mg / 100g, which means that if this value is exceeded, the quality is unacceptable.

[0070] Figure 2 is the change of TVB-N value during storage of Examples 1-5 and Comparative Examples 1-6; Figure 2It can be seen that the TVB values ​​of Comparative Examples 1-3 and Comparative Examples 5-6 decrease as the treatment time increases, indicating that the preservation effect of hydroxyl radicals becomes better as the hydroxyl radical treatment time increases, while the TVB value of Comparative Example 4 is significantly higher than that of Comparative Examples 2 and Comparative Examples 5-6, indicating that the long treatment time exacerbates the oxidation of protein in large yellow croaker, which has an adverse effect on the preservation of large yellow croaker. The TVB-N value of the sample in Comparative Example 1 has exceeded the acceptable limit on the third day of storage, the TVB-N value of the sample in Comparative Example 2 is still lower than the primary freshness limit on the third day of storage, and exceeds the acceptable limit on the eighth day, and the TVB-N value of the sample in Example 1 is 29.3 on the 9th day of storage, which is still lower than the acceptable limit. It shows that an embodiment of the present invention can delay the corruption of large yellow croaker and extend the shelf life of large yellow croaker by about 6 days, and the hydroxyl radical water combined with thymol treatment can further extend the shelf life on the basis of hydroxyl radical treatment.

[0071] Changes in total thiol content:

[0072] The total thiol content can reflect the oxidation level of proteins during the preservation of marine fish to a certain extent. Thiol groups are composed of latent and active groups, and their content in fish can reveal the degree of polymerization and degradation of myofibrillar proteins. Therefore, thiol groups can be used as the main indicator of protein denaturation, reflecting the changes in the spatial conformation of proteins. A relatively high thiol content is considered to be a characteristic of good quality of large yellow croaker.

[0073] Figure 3 is the change of total thiol content during storage of Examples 1-5 and Comparative Examples 1-6; Figure 3 It can be seen that the total thiol content of the sample in Comparative Example 1 decreased significantly during storage. The total thiol content in the samples of Comparative Example 2 and Comparative Examples 5-6 was higher than that in Comparative Example 1, indicating that hydroxyl radical water treatment can effectively delay protein denaturation. The total thiol content of the sample in Comparative Example 4 also decreased significantly during storage, indicating that too long a treatment time will accelerate the oxidation of protein in large yellow croaker. The total thiol content in the samples of the five embodiments decreased less, and still maintained a high content in the later stage of storage, indicating that hydroxyl radical combined with thymol treatment can effectively delay protein denaturation on the basis of hydroxyl radical water treatment.

[0074] TBARs value changes:

[0075] The TBARs value can reflect the degree of fat oxidation in aquatic products during storage. The higher the TBARs value, the higher the degree of fat oxidation in the aquatic products, and the less acceptable it is.

[0076] Figure 4 is the change of TBARs value during storage of Examples 1-5 and Comparative Examples 1-6; Figure 4It can be seen that the TBARs values ​​of Comparative Examples 1 and 3 increased rapidly during storage, and the TBARs values ​​of Comparative Examples 2 and 5-6 samples increased more slowly during storage than those of Comparative Examples 1 and 3, indicating that hydroxyl radical water treatment can effectively prevent fat oxidation. The TBARs value in the sample of Comparative Example 4 is also relatively high, indicating that too long a treatment time will accelerate the oxidation of fat in large yellow croaker. The TBARs values ​​of the five examples have remained at a low level, indicating that hydroxyl radical water combined with thymol treatment can delay fat oxidation on the basis of hydroxyl radical water treatment.

[0077] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for antibacterial preservation of fresh large yellow croaker based on hydroxyl free radicals, characterized in that: The steps include: Remove the head, fins and scales of fresh yellow croaker, clean it, and then soak it in water equipped with a hydroxyl free radical generator; take it out and soak it in thymol solution again, then take it out to remove surface moisture and refrigerate it.

2. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 1, characterized in that: The water containing hydroxyl free radicals is prepared by using a hydroxyl free radical generating device.

3. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 2, characterized in that: The pH value of water containing hydroxyl radicals is 5.87-6.

92.

4. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 1, characterized in that: Soak in water containing hydroxyl free radicals for 8-12 minutes.

5. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 1, characterized in that: Soak in water containing hydroxyl free radicals for 10 minutes.

6. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 1, characterized in that: The concentration of thymol solution was 100 mg / L.

7. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 1, characterized in that: Soak in thymol solution for 3-7 minutes.

8. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 1, characterized in that: Soak in thymol solution for 4-6 minutes.

9. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 1, characterized in that: Use absorbent paper to remove moisture from the surface of the large yellow croaker.

10. The antibacterial and fresh-keeping method of fresh large yellow croaker based on hydroxyl radicals according to claim 1, characterized in that: The refrigeration temperature is 4-8℃.

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