Quality and freshness keeping method of fresh meat

Abstract

The invention relates to the technical field of fresh keeping of meat products, in particular to a quality and fresh keeping method of fresh meat. According to the method, fresh meat is subjected to modified atmosphere packaging by adopting mixed gas of carbon dioxide and nitrogen, a specially-made water absorption liner is adopted in the modified atmosphere packaging, and the surface with small water permeable holes is placed downwards when the modified atmosphere packaging is used; and putting the product subjected to modified atmosphere packaging into a quick freezing room for cooling, and then storing by using an alternating electromagnetic field in combination with ice temperature. The method can effectively solve the problems of short shelf life and serious juice loss rate in logistics and storage processes of fresh meat, especially high-value fresh meat, realizes quality and freshness preservation of the high-value fresh meat, is good in water binding capacity and color and luster keeping effect, can be quickly and conveniently applied to fresh meat enterprises, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of meat preservation, and in particular to a method for preserving the quality and freshness of fresh meat. Background Art

[0002] Due to the rich nutrients and high water content of fresh meat, according to the requirements of relevant laws, regulations and standards, no preservatives and antioxidants can be added to fresh meat during storage, transportation and circulation. Therefore, fresh meat is very easy to spoil, especially high-value fresh meat such as Tan mutton, black pork and marbled beef. The preservation of quality has always been a difficulty and pain point in the industry.

[0003] Fresh meat packaged in modified atmosphere will leak juice and water during circulation and storage, causing changes in product quality and state, and easily breed microorganisms, affecting the freshness and shelf life of the product. Although the absorbent pad in the modified atmosphere packaging box can effectively absorb juice and water, a large number of microorganisms will also breed in the absorbent pad after absorbing juice and water, thus affecting the bacterial distribution of the entire microenvironment in the modified atmosphere packaging box.

[0004] Therefore, how to inhibit the growth of microorganisms in the absorbent pad to extend the shelf life of fresh meat and reduce the juice loss rate of fresh meat has become a technical problem that needs to be solved urgently in the field. Summary of the invention

[0005] In order to solve the above technical problems, the present invention first provides a water-absorbent pad, which is made of a mixture aqueous solution of polyvinyl alcohol, citric acid and ε-polylysine through an electrospinning process.

[0006] The present invention finds that the water-absorbing pad made by electrostatic spinning of the aqueous solution of the mixture formed by the above three substances can effectively solve the problems of quality deterioration and microbial growth caused by the leakage of juice and water of fresh meat after modified atmosphere packaging.

[0007] Preferably, the degree of polymerization of polyvinyl alcohol is 1700, and the degree of alcoholysis is 99%; and / or the molecular weight of ε-polylysine is 3300-4500 Da.

[0008] Preferably, the mass volume ratio of polyvinyl alcohol to the aqueous mixture solution is (7-8) g:100 mL; the mass volume ratio of citric acid to the aqueous mixture solution is (0.6-0.8) g:100 mL; and the mass volume ratio of ε-polylysine to the aqueous mixture solution is (0.5-2) g:100 mL.

[0009] Preferably, the mass volume ratio of ε-polylysine to the aqueous mixture solution is (0.8-1.5) g:100 mL.

[0010] Preferably, the electrospinning process parameters include: applied voltage of 12-18 kV, injection rate of 0.2-0.3 mL / h, receiving distance of 10-15 cm, temperature of 28-32°C, relative humidity of 40%-50%, and nanofiber heating temperature of 125-135°C.

[0011] Preferably, the water-absorbing pad is packaged with a polyethylene film, and has water-permeable pores with a diameter of 0.5 μm to 1.2 μm (preferably 0.8 μm to 1 μm) on one side.

[0012] Furthermore, the present invention provides a modified atmosphere packaging box containing the water-absorbing pad.

[0013] Furthermore, the present invention provides the use of the water-absorbing pad or the modified atmosphere packaging box in preserving the quality and freshness of fresh meat.

[0014] Furthermore, the present invention provides a method for preserving the quality and freshness of fresh meat, comprising: packaging the fresh meat with a mixture of carbon dioxide and nitrogen, using the absorbent pad in the modified atmosphere packaging, and placing the surface with the water-permeable holes downward when in use; placing the product after the modified atmosphere packaging in a quick freezing room for cooling, and then using an alternating electromagnetic field combined with ice temperature storage.

[0015] When in use, place the side with the water-permeable holes downwards, which not only allows moisture to be absorbed from the bottom but also does not actively absorb moisture from the fresh meat, effectively maintaining the quality of the fresh meat. At the same time, the absorbent pad can effectively inhibit the growth of microorganisms after the absorbent pad absorbs juice, thereby improving the shelf life of fresh meat.

[0016] Electromagnetic field is a physical field generated by charged objects, including electric field and magnetic field, which are interconnected and interdependent. As a non-thermal processing technology, electromagnetic field treatment technology has the advantages of safety, high efficiency, simple operation, and green environmental protection. Under the action of alternating electromagnetic field, the electronic spin and nuclear spin of water molecules in fresh meat are redirected, and the hydrogen bonds between water molecules will show a tendency to rotate under the action of Lorentz force, which will destroy the stability of hydrogen bonds, and then cause the water molecules to rearrange regularly, thereby reducing the freezing point of fresh meat; under the action of alternating electromagnetic field, the polar phospholipid bilayer of fresh meat cell membrane is arranged more closely, and the water molecule structure on the surface of cell membrane is also affected. Under the action of alternating electromagnetic field, polar charged ions in cell membrane will cause changes in membrane voltage, resulting in reduced conductivity and permeability of cell membrane, thereby reducing the exudation of water and juice in fresh meat. In addition, alternating magnetic field will also change the arrangement and distribution of water in microorganisms, and inhibit the growth of microorganisms by affecting the permeability of cell membrane, thereby extending the shelf life of fresh meat.

[0017] Preferably, the volume percentage of carbon dioxide in the mixed gas is 85% to 95%; and / or the volume percentage of nitrogen in the mixed gas is 5% to 15%; and / or the temperature in the quick-freezing room is below -15°C; and / or the temperature of the center of the fresh meat is cooled to 2 to 4°C.

[0018] More preferably, the temperature of the quick freezing room is -15°C to -20°C.

[0019] The low temperature in the quick-freezing room can quickly reduce the temperature of fresh meat to 2°C~4°C, slowing down the growth of microorganisms; however, too low a temperature will cause partial freezing of fresh meat in a short period of time, affecting the texture and color quality of the fresh meat.

[0020] Preferably, the intensity of the alternating electromagnetic field is 2-6 mT, the frequency is 40-60 Hz, and the uniformity is above 95%; and / or the temperature of the ice storage is -2°C to -6°C.

[0021] More preferably, the intensity of the alternating electromagnetic field is 3-5 mT, the frequency is 40-60 Hz, and the uniformity is above 99%.

[0022] In the specific implementation process, the temperature of the ice storage is mainly determined according to the freezing point of different fresh meats. The freezing point of fresh meat varies with species and parts. Especially under the treatment of electromagnetic fields, the freezing point of fresh meat will be further reduced. Therefore, the storage temperature needs to be determined according to the specific type of fresh meat.

[0023] Preferably, the fresh meat is fresh mutton, fresh beef or fresh pork.

[0024] Preferably, the fresh meat is high-value fresh meat, including but not limited to Tan mutton, marbled beef, black pork, etc.

[0025] Those skilled in the art can combine the above preferred solutions to obtain better implementation plans.

[0026] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preserving the quality and freshness of fresh meat, which can effectively solve the problems of short shelf life and serious juice loss rate during the logistics and storage of fresh meat, especially high-value fresh meat, and achieve the quality and freshness preservation of high-value fresh meat, with good water retention and color retention effects. The method can be quickly and conveniently applied to fresh meat companies and has broad application prospects. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The endpoints and any values ​​of the ranges disclosed in this specification are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] In the examples provided in this specification, if no specific techniques or conditions are specified, the techniques or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased through regular channels.

[0030] Example 1 This embodiment provides a method for preserving the quality and freshness of fresh meat, and the specific steps are as follows: (1) Packaging of Tan mutton: A water-absorbing pad was placed in a modified atmosphere packaging box. The water-absorbing pad was made of a mixture of polyvinyl alcohol, citric acid and ε-polylysine by electrospinning. In the mixture, the mass volume ratio of polyvinyl alcohol (degree of polymerization of 1700, degree of alcoholysis of 99%) to the mixture was 7.5 g:100 mL; the mass volume ratio of citric acid to the mixture was 0.7 g:100 mL; the mass volume ratio of ε-polylysine (molecular weight of 3300-4500 Da) to the mixture was 1 g:100 mL. The electrospinning process parameters were as follows: applied voltage of 15 kV, injection rate of 0.24 mL / h, receiving distance of 12 cm, temperature of 30 °C, relative humidity of 40%-50%, and the collected nanofibers were heated at 130 °C for 8 min to obtain an esterified cross-linked electrospun water-absorbing pad. The absorbent pad is packaged with a polyethylene film, with small holes with a diameter of 0.9 μm on one side that allow water to pass through, and the holed side is placed face down; about 250 g of fresh Tan sheep hind leg meat that has been cut is put into a packaging box and packaged with a modified atmosphere of 90% CO2 and 10% N2.

[0031] (2) Cooling of Tan mutton: Place the packaged fresh Tan mutton hind leg meat in a -18°C rapid cooling room to cool the core temperature of the fresh Tan mutton hind leg meat to 2°C~4°C.

[0032] (3) Alternating electromagnetic field combined with ice temperature storage and preservation: The cooled modified atmosphere packaged fresh Tan sheep hind leg meat is stored in an environment with a temperature of -2°C, an electromagnetic field strength of 4mT, a frequency of 50Hz, and a uniformity of 99% for preservation.

[0033] Example 2 This embodiment provides a method for preserving the quality and freshness of fresh meat, and the specific steps are only different from those in Embodiment 1 in that: (1) The Tan mutton is replaced with Beijing black pork tenderloin of the same quality.

[0034] (3) The cooled modified atmosphere packaged fresh Beijing black pork tenderloin was placed in an environment with a temperature of -1.5°C, an electromagnetic field strength of 4 mT, a frequency of 50 Hz, and a uniformity of 99% for storage and preservation.

[0035] Example 3 This embodiment provides a method for preserving the quality and freshness of fresh meat, and the specific steps are only different from those in Embodiment 1 in that Tan mutton is replaced with Tongliao cattle top brain meat of the same quality.

[0036] Comparative Example 1 This comparative example provides a method for preserving the quality and freshness of fresh meat, and the specific steps are different from those of Example 1 only in that ε-polylysine is replaced by an equal amount of nisin.

[0037] Comparative Example 2 This comparative example provides a method for preserving the quality and freshness of fresh meat, and the specific steps are different from those of Example 1 only in that no water-absorbing pad is placed in the modified atmosphere packaging box.

[0038] Comparative Example 3 This comparative example provides a method for preserving the quality and freshness of fresh meat, and the specific steps are different from those of Example 1 only in that the packaged fresh Tan sheep hind leg meat is not placed in a rapid cooling room for cooling.

[0039] Comparative Example 4 This comparative example provides a method for preserving the quality and freshness of fresh meat, and the specific steps are only different from those of Example 1 in that: step (3) only places the cooled atmosphere-packaged fresh tan lamb hind leg meat in an environment with a temperature of -2°C for storage and preservation.

[0040] Test example This test example tests the shelf life of the fresh meat of the above embodiment and comparative example and the juice loss rate on the 30th day of storage. The specific method is as follows: The total colony count was determined according to the Chinese standard (GB 5009.228-2016). About 10 g of mutton sample and 90 mL of sterile saline solution (NaCl, 0.85%) were placed in a sterile bag, and then the bag was beaten with a Stomacher paddle homogenizer for 2 minutes to obtain a stock solution. The stock solution was serially diluted and counted using the surface plate method to calculate the total colony count per gram of sample log (CFU / g). When the total colony count exceeded 6, it was judged to be beyond the shelf life.

[0041] Juice loss rate: weigh the initial weight of the meat sample and record it as m1. Take out the sample after storage, remove the juice that seeps out from the surface, weigh the sample, and record the weight as m2. Juice loss rate = (m1-m2) / m1*100%.

[0042] The test results are shown in Table 1.

[0043] Table 1

[0044] Result analysis: All embodiments have the best shelf life and juice loss prevention effects. Comparative Example 2 did not place a water-absorbing pad. Since the meat was soaked in water for a long time, the structure of the meat became loose, which increased the juice loss rate of the fresh meat. Comparative Example 3 did not place the meat in a quenching room for cooling, which prolonged the time it took for the fresh meat to drop from the temperature after cutting to the final storage temperature, which was not conducive to the control of microorganisms. Therefore, the shelf life of the fresh meat was shortened. Comparative Example 4 did not use an alternating magnetic field treatment, which caused the freezing point of the product to rise and the product to be slightly frozen. Although the shelf life of the product was relatively long, ice crystals were formed inside the product due to the freezing of the product, which caused the fresh meat cells to be damaged. When the product was thawed, more juice was lost and the taste of the product was damaged.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, 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 embodiments of the present invention.

Claims

1. A water-absorbent pad, characterized in that: The invention is prepared from a mixed aqueous solution of polyvinyl alcohol, citric acid and ε-polylysine through an electrostatic spinning process.

2. The water-absorbent pad according to claim 1, characterized in that: The degree of polymerization of polyvinyl alcohol is 1700, and the degree of alcoholysis is 99%; and / or the molecular weight of ε-polylysine is 3300-4500 Da.

3. The water-absorbent pad according to claim 1, characterized in that: The mass volume ratio of polyvinyl alcohol to the aqueous mixture solution is (7-8) g:100 mL; the mass volume ratio of citric acid to the aqueous mixture solution is (0.6-0.8) g:100 mL; and the mass volume ratio of ε-polylysine to the aqueous mixture solution is (0.5-2) g:100 mL.

4. The water-absorbent pad according to claim 1, characterized in that: The water-absorbing pad is packaged with a polyethylene film, and has water-permeable holes with a diameter of 0.5 μm to 1.2 μm on one side.

5. A modified atmosphere packaging box comprising the water-absorbent liner according to any one of claims 1 to 4.

6. Use of the water-absorbing pad according to any one of claims 1 to 4 or the modified atmosphere packaging box according to claim 5 in preserving the quality and freshness of fresh meat.

7. A method for preserving the quality and freshness of fresh meat, characterized in that: include: Fresh meat is packaged in a modified atmosphere using a mixture of carbon dioxide and nitrogen, and the water-absorbing pad described in any one of claims 1 to 4 is used in the modified atmosphere packaging, and is placed with the water-permeable holes facing downward when in use; the product after the modified atmosphere packaging is placed in a quick freezing room for cooling, and then stored using an alternating electromagnetic field combined with ice temperature.

8. The method for preserving quality and freshness according to claim 7, characterized in that: The volume percentage of carbon dioxide in the mixed gas is 85% to 95%; and / or the volume percentage of nitrogen in the mixed gas is 5% to 15%; and / or the temperature in the quick-freezing room is below -15°C; and / or the temperature at the center of the fresh meat is cooled to 2 to 4°C.

9. The method for preserving quality and freshness according to claim 7 or 8, characterized in that: The intensity of the alternating electromagnetic field is 2-6 mT, the frequency is 40-60 Hz, and the uniformity is above 95%; and / or the temperature of the ice storage is -2°C to -6°C.

10. The method for preserving quality and freshness according to claim 7, characterized in that: The fresh meat is fresh mutton, fresh beef or fresh pork.

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