Method for improving eating quality and safety quality of salt roasted chicken based on low-temperature plasma and EGCG (epigallocatechin gallate) treatment

Abstract

The invention discloses a method for improving eating and safety quality of salt roasted chicken based on low-temperature plasma and EGCG (epigallocatechin gallate) treatment. The preparation method comprises the following steps: by taking fresh chicken as a raw material, cleaning, removing hair, removing fat and fascia, pickling with salt and cooking wine, soaking in prepared marinating soup for marinating, treating with dielectric barrier discharge type low-temperature plasma equipment and soaking with an EGCG (epigallocatechin gallate) solution, and carrying out vacuum packaging and cold storage. The electric field discharge frequency of the dielectric barrier discharge type low-temperature plasma equipment is controlled to be 25-35 kHz, and the discharge voltage is controlled to be 40-60 kV; an EGCG aqueous solution with the mass concentration of 0.05-0.15% is controlled to be adopted in the EGCG soaking treatment, and the soaking time is 10-15 min. According to the invention, the shelf life of the salt-roasted chicken can be prolonged by 14 days, fat oxidation and volatile basic nitrogen accumulation of the salt-roasted chicken are delayed, the color and texture of the salt-roasted chicken are maintained, and the comprehensive commodity value of the salt-roasted chicken is improved.

Description

Technical Field

[0001] This invention relates to the preparation of salt-baked chicken, specifically to a method for improving the edibility and safety of salt-baked chicken during storage using low-temperature plasma combined with EGCG; it belongs to the field of meat processing technology. Background Technology

[0002] Chicken is a highly nutritious and important part of the human diet, rich in protein and vitamins. However, it is also an excellent breeding ground for microorganisms, easily leading to the growth of bacteria and other pathogenic microorganisms, thus posing a potential threat to consumer health. As a ready-to-eat or instant-heat pre-processed dish, salt-baked chicken is susceptible to microbial contamination during industrial production, transportation, and sales, affecting its quality and safety. Currently, the main processing methods for salt-baked chicken include salt-baking, water-baking, and air-baking. Among them, salt-baking, as the most traditional and classic process, uses a salt medium to slowly heat the chicken in a closed environment, gradually cooking it and maintaining its tenderness and juiciness. However, due to the complexity and long processing time of this process, industrial production generally uses water-baking, whose typical process flow is: raw material pretreatment → seasoning → marinating → braising → vacuum packaging → rapid cooling → metal detection → outer packaging. With repeated use of the braising liquid, microorganisms accumulate continuously, resulting in a high initial total bacterial count and a short shelf life for the finished salt-baked chicken. To extend shelf life, the industry currently widely uses prolonged high-temperature heat sterilization. However, this technology easily leads to quality deterioration problems such as softened texture, significant loss of nutrients, and altered flavor. Therefore, it is essential to develop non-heat sterilization technologies suitable for salt-baked chicken.

[0003] Epigallocatechin gallate (EGCG), as the main active ingredient of tea polyphenols, is a natural and highly effective antioxidant and antibacterial agent. Studies have shown that EGCG can effectively inhibit microbial growth in various food systems and delay the oxidation process of lipids and proteins, while also meeting the modern consumer preference for natural and healthy food preservatives. Chinese invention patent application CN202510259151.7 discloses a research method for controlling the quality deterioration of seasoned chicken wings during frozen storage using steady-state EGCG. Steady-state EGCG was used to control the quality deterioration of chicken wings during 0-4 freeze-thaw cycles, effectively controlling adverse changes in thiobarbituric acid value, volatile basic nitrogen value, and sensory properties. However, using EGCG alone as a marinade cannot achieve rapid and efficient surface sterilization and is insufficient in controlling initial microbial contamination. Summary of the Invention

[0004] To address the shortcomings of existing technologies, such as the difficulty in achieving rapid and efficient surface sterilization of salt-baked chicken through epigallocatechin gallate immersion treatment and insufficient control over initial microbial contamination, this invention aims to provide a method for achieving efficient sterilization and high-efficiency antioxidant effects through epigallocatechin gallate immersion treatment, comprehensively maintaining the edibility and safety of salt-baked chicken during storage, and synergistically using low-temperature plasma equipment treatment.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment: Fresh chicken meat is used as raw material. After cleaning, removing feathers, fat and tendons, it is marinated with salt and cooking wine, then braised in a prepared braising liquid. After treatment with a dielectric barrier discharge type low-temperature plasma device and EGCG solution soaking, it is vacuum packaged and refrigerated. The electric field discharge frequency of the dielectric barrier discharge type low-temperature plasma device is controlled at 25-35 kHz and the discharge voltage is controlled at 40-60 kV. The EGCG soaking treatment uses an EGCG aqueous solution with a mass concentration of 0.05-0.15% and a soaking time of 10-15 min.

[0007] To further achieve the purpose of this invention, preferably, the discharge time of the dielectric barrier discharge type low-temperature plasma device is 60-180 s.

[0008] Preferably, the electric field discharge frequency of the dielectric barrier discharge type low-temperature plasma device is 25-35 kHz.

[0009] Preferably, the discharge voltage of the dielectric barrier discharge type low-temperature plasma device is 40-60 kV.

[0010] Preferably, the discharge of the dielectric barrier discharge type low-temperature plasma device is carried out at room temperature, using air as the working gas.

[0011] Preferably, the EGCG immersion treatment is carried out at a temperature of 4-30°C.

[0012] Preferably, the mass ratio of EGCG to salt-baked chicken is 1:400-3:400.

[0013] Preferably, the marinating time is 2-4 hours; the braising time is 20-30 minutes.

[0014] Preferably, the refrigerated storage temperature is 4-8℃, and the storage time is within 18 days.

[0015] Preferably, the braising temperature is controlled at a gentle boil of 90-95℃, and the braising time is 20-30 minutes.

[0016] Compared with the prior art, the present invention has the following advantages, disadvantages and beneficial effects:

[0017] (1) The active substances generated by the low-temperature plasma used in this invention can kill microorganisms on the surface of salt-baked chicken in a short time. At the same time, since EGCG has broad-spectrum antibacterial activity, it can inhibit the growth and reproduction of microorganisms in salt-baked chicken. The two work synergistically to achieve a highly efficient and long-lasting antibacterial effect. The shelf life of salt-baked chicken prepared by traditional methods under refrigeration is about 4 days. The method of this invention can effectively extend the shelf life of salt-baked chicken to 14 days.

[0018] (2) The low-temperature plasma combined with EGCG technology used in this invention significantly delayed the increase in thiobarbituric acid value, which was 1.43 mg / kg after 18 days of storage. -1 This reduces the dosage by 0.73 mg / kg compared to traditional methods. -1 It slows down the accumulation of volatile basic nitrogen, and its value is 7.93 mg / 100 g after 18 days of storage. -1 The dosage was reduced by 11.67 mg per 100 g compared to traditional methods. -1 Effectively maintains the unique edible quality of salt-baked chicken.

[0019] (3) The technical process used in this invention avoids the damage to the texture and flavor of the product caused by high-temperature heat processing. The EGCG used is a natural antioxidant, which is safe and harmless, and will not have a significant impact on the flavor of the product.

[0020] (4) In view of the technical defects of the single low-temperature plasma technology in the treatment of meat products such as salt-baked chicken, although it can effectively sterilize, it will also cause lipid oxidation, which leads to the deterioration of product color and nutritional quality. The present invention found that low-temperature plasma treatment and EGCG treatment can effectively give full play to the high efficiency of low-temperature plasma sterilization, while effectively inhibiting the oxidative deterioration caused by it.

[0021] (5) The method of improving the edible and safe quality of salt-baked chicken based on low-temperature plasma and EGCG treatment has good effects on controlling the total number of colonies in salt-baked chicken and significantly extending the shelf life, while also showing good effects on unpleasant odors (TVB-N value), fat oxidation (TBARS value), hardness and color retention. The overall effect is significant, improving the industrial production quality of salt-baked chicken and promoting industrial technological progress. Attached Figure Description

[0022] Figure 1 The bactericidal effects of Examples 1-7 and Comparative Examples 1-4 on salt-baked chicken in this application

[0023] Figure 2 The changes in total bacterial count of salt-baked chicken during storage were treated in Example 7 and Comparative Examples 2, 4, and 5 of this application.

[0024] Figure 3 Example 7 and Comparative Examples 2, 4, and 5 of this application treat the changes in TVB-N values ​​of salt-baked chicken during storage.

[0025] Figure 4 Example 7 and Comparative Examples 2, 4, and 5 of this application treat the changes in TBARS values ​​of salt-baked chicken during storage. Detailed Implementation

[0026] To better understand the present invention, it will be further described below with reference to the accompanying drawings and specific embodiments. However, the implementation of the present invention is not limited thereto. The described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Since EGCG immersion treatment cannot achieve rapid and efficient surface sterilization of salt-baked chicken and is insufficient in controlling initial microbial contamination, combining it with effective sterilization measures has become a common approach for improvement. However, existing commonly used sterilization methods and EGCG immersion treatments are not ideal in terms of results.

[0028] Cold plasma (CP) technology, as an emerging non-thermal processing technology, has shown great potential in the field of food sterilization and preservation due to its advantages such as high sterilization efficiency, low operating temperature, and environmental friendliness. It is widely used in many fields, including food anti-allergy treatment, seed germination, packaging material surface treatment, food functional modification, and extraction of bioactive substances. The dielectric barrier discharge (DBD) type cold plasma device used in this invention is model CTP-2000K, manufactured by Nanjing Suman Plasma Co., Ltd. It is an assembled integrated device, including a high-voltage electric field generator, a voltage regulator, two electrodes, and an external insulating plate of arbitrary flatness, with an electrode distance of 2-3 cm. The DBD type cold plasma device mainly controls the discharge frequency and discharge voltage, and also includes time control. Due to its ease of operation, excellent scalability, and industrial applicability, the DBD type cold plasma device is commonly used for the sterilization of fruits, vegetables, meat, and packaging materials. In the field of meat sterilization, dielectric barrier low-temperature plasma discharge equipment is mainly used for processing fresh meat. For example, Chinese invention patent application CN201710255636.4 discloses a method and device for meat preservation. This method involves introducing low-temperature plasma into a tray containing fresh meat for 1-3 minutes for sterilization. The low-temperature plasma is generated by a dielectric barrier discharge device using a mixture of O2, CO2, and N2 gases. Chinese invention patent application CN202311390985.9 discloses a method for cold sterilization and preservation of fresh fish using low-temperature plasma. Fresh fish is immersed in plasma-activated water at a temperature of 10-20°C for cleaning and sterilization. After sterilization, the fish is drained, placed in a sealed packaging box, and then subjected to DBD low-temperature plasma cold sterilization. Both of these existing technologies generate plasma by exciting gas through dielectric barrier discharge, etc. The large number of free radicals and nitrogen and oxygen reactive substances contained within the plasma can effectively destroy the cell membranes, proteins, and DNA of microorganisms, thereby achieving rapid sterilization. However, when applying low-temperature plasma technology directly to meat products with high fat content, such as salt-baked chicken, a serious challenge is faced: the strong oxidizing active substances generated by plasma during the sterilization process may exacerbate lipid oxidation on the product surface while killing microorganisms, leading to rancidity of fatty acids, producing unpleasant flavors, and causing oxidative denaturation of muscle proteins, thereby deteriorating the color, flavor, and nutritional value of the product.

[0029] Due to the high fat content of salt-baked chicken, based on the above description, it is difficult for those skilled in the art to combine EGCG soaking treatment with low-temperature plasma for use in salt-baked chicken. EGCG has a unique polyphenol structure, and its hydroxyl groups (ortho-dihydroxy or trihydroxy structures) can chelate metal ions, effectively scavenging free radicals and interrupting the oxidation chain reaction, thereby reducing the generation of odorous fat oxidation secondary products from the source. This invention has found that after low-temperature plasma treatment, microstructured pores are formed on the surface of the chicken meat, which may enhance the penetration of EGCG into the interior, thus significantly enhancing the effect of EGCG soaking. At the same time, EGCG soaking treatment requires a low concentration, otherwise it will introduce a bitter taste; the synergistic effect of low-temperature plasma treatment depends on the intensity of the low-temperature plasma treatment (electric field discharge frequency and discharge voltage). Too low an intensity will not have a synergistic effect, while too high an intensity will destroy the effect of EGCG soaking. Based on the above findings, this invention has determined through testing that, in order to leverage the synergistic effect of low-temperature plasma treatment and EGCG immersion treatment, the electric field discharge frequency of the dielectric barrier discharge type low-temperature plasma device should be controlled at 25-35 kHz, and the discharge voltage at 40-60 kV; the EGCG immersion treatment should use an EGCG aqueous solution with a mass concentration of 0.05-0.15% and an immersion time of 10-15 min.

[0030] Based on this, the method for improving the edibility and safety of salt-baked chicken by low-temperature plasma and EGCG treatment provided by the present invention includes the following steps:

[0031] Step 1: Raw material processing. Using fresh chicken as the raw material, clean it thoroughly, removing any stray feathers, excess fat, and tendons. This step is a common practice for salt-baked chicken. Cleaning aims to remove surface blood and impurities, using running water for rinsing; feather removal must be thorough, ensuring no remaining feather roots or downy hairs remain on the carcass; removing excess fat and tendons is for shaping and improving the final product's texture, generally requiring the removal of obvious fat deposits and major extramuscular fascia from areas such as the neck, tail, and abdominal cavity.

[0032] Step Two: Marinating: Marinate the processed chicken with salt and cooking wine; this is a standard practice, as pre-treated chicken needs to be marinated with salt and cooking wine. In existing technologies, the main purpose of marinating is to infuse flavor, remove any fishy smell, and firm the meat. Using a wet marinating method, the preferred amount of salt is 3% of the chicken's weight, and the preferred amount of cooking wine is 2% of the chicken's weight. The marinating time is typically 2-4 hours, preferably under a refrigerated environment of 4-8℃ to ensure safety and promote the penetration of flavor compounds.

[0033] Step 3: Brine Preparation and Braising: Boil water with the salt-baking brine to obtain the brine. Immerse the marinated chicken in the brine and braise. After braising, remove the salt-baked chicken, drain, and cool to room temperature. This step is standard practice. After marinating, the chicken needs to be immersed in the prepared brine for braising. The brine is made by boiling water, salt, spices (sand ginger, star anise, Sichuan peppercorns, etc.) and seasonings. The braising temperature is controlled at a gentle boil (90-95℃), and the braising time is preferably 20-30 minutes. The salt-baking brine used in this invention can be commercially available Jiawen Salt-Baked Chicken Powder, manufactured by Meizhou Hongxing Food Co., Ltd.

[0034] Step 4: Low-temperature plasma treatment: The prepared salt-baked chicken is placed under the high-voltage electric field of a low-temperature plasma device for treatment. Air is used as the working gas, the treatment temperature is room temperature, the discharge frequency is 25-35 kHz, the discharge voltage is 40-60 kV, and the preferred treatment time is 60-180 s.

[0035] Step 5: EGCG Immersion Treatment: Immerse the salt-baked chicken, which has undergone low-temperature plasma treatment, in an EGCG aqueous solution with a mass concentration of 0.05-0.15% for immersion treatment at a temperature of 4-30℃ for 10-15 minutes. The preferred mass ratio of EGCG to salt-baked chicken is 1:400-3:400.

[0036] Step Six: Packaging and Storage: After soaking, remove the salt-baked chicken and drain excess water. Vacuum pack and store under refrigeration. This step is standard practice. The preferred refrigeration temperature is 4-8℃, and the storage time is controlled within 18 days.

[0037] The raw material processing, marinating, brine preparation, and braising in the following embodiments are all conventional practices in the field, as described above. The following embodiments will not be elaborated on in detail.

[0038] Example 1

[0039] A method for improving the quality of salt-baked chicken during storage using low-temperature plasma combined with EGCG includes the following steps:

[0040] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0041] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 4 hours;

[0042] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 20 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0043] (4) Low-temperature plasma treatment: The prepared salt-baked chicken is placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency as 25 kHz, discharge voltage as 40 kV, and treatment time as 60 s.

[0044] (5) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.05% for soaking treatment, and the mass ratio of EGCG to salt-baked chicken was controlled at 1:400; the treatment temperature was 30℃ and the soaking time was 10 min;

[0045] (6) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0046] Samples of salt-baked chicken from Example 1, stored for different periods, were immediately used to determine the total bacterial count.

[0047] Example 2

[0048] A method for improving the quality of salt-baked chicken during storage using low-temperature plasma combined with EGCG includes the following steps:

[0049] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0050] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0051] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0052] (4) Low-temperature plasma treatment: The prepared salt-baked chicken was placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency of 35 kHz, discharge voltage of 60 kV, and treatment time of 180 s.

[0053] (5) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.15% for soaking treatment. The mass ratio of EGCG to salt-baked chicken was 3:400. The treatment temperature was 4℃ and the soaking time was 15 min.

[0054] (6) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0055] Samples of salt-baked chicken from Example 2, stored for different periods, were immediately used to determine the total bacterial count.

[0056] Example 3

[0057] A method for improving the quality of salt-baked chicken during storage using low-temperature plasma combined with EGCG includes the following steps:

[0058] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0059] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0060] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0061] (4) Low-temperature plasma treatment: The prepared salt-baked chicken is placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency of 25 kHz, discharge voltage of 40 kV, and treatment time of 180 s.

[0062] (5) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.15% for soaking treatment. The mass ratio of EGCG to salt-baked chicken was 3:400. The treatment temperature was 30℃ and the soaking time was 10 min.

[0063] (6) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0064] Samples of salt-baked chicken from Example 3, stored for different periods, were immediately used to determine the total bacterial count.

[0065] Example 4

[0066] A method for improving the quality of salt-baked chicken during storage using low-temperature plasma combined with EGCG includes the following steps:

[0067] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0068] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0069] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0070] (4) Low-temperature plasma treatment: The prepared salt-baked chicken is placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency of 35 kHz, discharge voltage of 60 kV, and treatment time of 60 s.

[0071] (5) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.05% for soaking treatment. The mass ratio of EGCG to salt-baked chicken was 1:400. The treatment temperature was 4℃ and the soaking time was 15 min.

[0072] (6) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0073] Samples of salt-baked chicken from Example 4, stored for different periods, were immediately used to determine the total bacterial count.

[0074] Example 5

[0075] A method for improving the quality of salt-baked chicken during storage using low-temperature plasma combined with EGCG includes the following steps:

[0076] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0077] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0078] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0079] (4) Low-temperature plasma treatment: The prepared salt-baked chicken is placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency of 30 kHz, discharge voltage of 40 kV, and treatment time of 60 s.

[0080] (5) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.15% for soaking treatment. The mass ratio of EGCG to salt-baked chicken was 3:400. The treatment temperature was 4℃ and the soaking time was 15 min.

[0081] (6) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0082] Samples of salt-baked chicken from Example 1, stored for different periods, were immediately used to determine the total bacterial count.

[0083] Example 6

[0084] A method for improving the quality of salt-baked chicken during storage using low-temperature plasma combined with EGCG includes the following steps:

[0085] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0086] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0087] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0088] (4) Low-temperature plasma treatment: The prepared salt-baked chicken is placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency of 30 kHz, discharge voltage of 60 kV, and treatment time of 180 s.

[0089] (5) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.05% for soaking treatment. The mass ratio of EGCG to salt-baked chicken was 1:400. The treatment temperature was 4℃ and the soaking time was 15 min.

[0090] (6) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0091] Samples of salt-baked chicken from Example 1, stored for different periods, were immediately used to determine the total bacterial count.

[0092] Example 7

[0093] A method for improving the quality of salt-baked chicken during storage using low-temperature plasma combined with EGCG includes the following steps:

[0094] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0095] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0096] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0097] (4) Low-temperature plasma treatment: The prepared salt-baked chicken is placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency of 30 kHz, discharge voltage of 50 kV, and treatment time of 120 s.

[0098] (5) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.1% for soaking treatment. The mass ratio of EGCG to salt-baked chicken was 1:200. The treatment temperature was 4℃ and the soaking time was 10 min.

[0099] (6) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0100] Samples of salt-baked chicken from Example 7, stored for different periods, were used to determine their hardness, color, total bacterial count, volatile basic nitrogen, and thiobarbituric acid content.

[0101] Comparative Example 1

[0102] A method for preparing salt-baked chicken includes the following steps:

[0103] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0104] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 4 hours;

[0105] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 20 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0106] (4) Low-temperature plasma treatment: The prepared salt-baked chicken is placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency as 25 kHz, discharge voltage as 40 kV, and treatment time as 60 s.

[0107] (5) Packaging and storage: After low-temperature plasma treatment, the salt-baked chicken is taken out of the equipment and vacuum-packed to obtain the finished salt-baked chicken, which is then stored at 4°C.

[0108] Take the salt-baked chicken sample from Comparative Example 1 and use it immediately to determine the total bacterial count.

[0109] Comparative Example 2

[0110] A method for preparing salt-baked chicken includes the following steps:

[0111] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0112] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0113] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0114] (4) Low-temperature plasma treatment: The prepared salt-baked chicken is placed in a dielectric barrier discharge type low-temperature plasma device, with air as the working gas, room temperature as the treatment temperature, discharge frequency of 30 kHz, discharge voltage of 50 kV, and treatment time of 120 s.

[0115] (5) Packaging and storage: After low-temperature plasma treatment, the salt-baked chicken is taken out of the equipment and vacuum-packed to obtain the finished salt-baked chicken, which is then stored at 4°C.

[0116] Salt-baked chicken samples from Comparative Example 2 were collected at different storage times to determine hardness, color, total bacterial count, volatile basic nitrogen, and thiobarbituric acid content.

[0117] Comparative Example 3

[0118] A method for preparing salt-baked chicken includes the following steps:

[0119] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0120] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 4 hours;

[0121] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 20 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0122] (4) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.05% for soaking treatment. The mass ratio of EGCG to salt-baked chicken was 1:400. The treatment temperature was 30℃ and the soaking time was 10 min.

[0123] (5) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0124] Take the salt-baked chicken sample from Comparative Example 3 immediately for determination of total bacterial count.

[0125] Comparative Example 4

[0126] A method for preparing salt-baked chicken includes the following steps:

[0127] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0128] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0129] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0130] (4) EGCG soaking treatment: The prepared salt-baked chicken was soaked in an EGCG aqueous solution with a mass concentration of 0.1% for soaking treatment. The mass ratio of EGCG to salt-baked chicken was 1:200. The treatment temperature was 4℃ and the soaking time was 10 min.

[0131] (5) Packaging and storage: After soaking in EGCG, the salt-baked chicken is taken out and the excess water on the surface is drained. Then it is vacuum-packed to obtain the finished salt-baked chicken and stored at 4℃.

[0132] Take the salt-baked chicken sample from Comparative Example 4 and use it immediately to determine the total bacterial count.

[0133] Comparative Example 5

[0134] A method for preparing salt-baked chicken includes the following steps:

[0135] (1) Raw material processing: Fresh chicken is used as raw material. It is cleaned and the surface hair, excess fat and tendons are removed.

[0136] (2) Marinating: Marinate the processed chicken with salt and cooking wine for 2 hours;

[0137] (3) Preparation and braising: Boil the salt-baked braising ingredients with water to obtain braising liquid, soak the marinated chicken in it and braise for 30 minutes. After braising, remove the salt-baked chicken, drain it, and cool it to room temperature.

[0138] (4) Packaging and storage: The prepared salt-baked chicken is vacuum-packed to obtain the finished salt-baked chicken, and stored at 4℃.

[0139] Samples of salt-baked chicken from Comparative Example 5, stored for different periods, were used to determine their hardness, color, total bacterial count, volatile basic nitrogen, and thiobarbituric acid content.

[0140] Table 1 Parameters for each implementation method

[0141] The parameters for the low-temperature plasma treatment and EGCG treatment in the examples and comparative examples are shown in Table 1. As shown in Table 1, the discharge frequency of the low-temperature plasma treatment in this invention is 25-35 kHz, and the discharge voltage is 40-60 kV; the treatment time has a relatively wide range, preferably 60-180 s. In the EGCG immersion treatment, the mass concentration of the EGCG aqueous solution is 0.05-0.15%, and the immersion time is 10-15 min; the treatment temperature varies considerably, and room temperature or 4-30℃ can be selected. Based on the parameter range, Example 7 is highly representative, and Example 7 is selected as the representative for the following tests, to assist in verifying the test results of Example 1; Comparative Examples 1 and 2, and Comparative Examples 3 and 4 are similar, differing only in some parameters, therefore Comparative Examples 2 and 4 are selected for comparison with the examples.

[0142] Total bacterial count test: Following the national food safety standard GB 2726-2016 (Food Microbiology Examination: Determination of Total Bacterial Count), the salt-baked chicken was chopped and mixed with sterile physiological saline. The mixture was diluted to a suitable gradient, and 0.1 mL of bacterial suspension was added to PCA (Potentially Calculated Agar) medium. The culture was incubated at 37°C for 48 h, and then the bacterial count was performed. The total bacterial count value is expressed logarithmically. The test results for the total bacterial count in the examples and comparative examples are as follows: Figure 1 As shown in Table 2, Figure 1 The bactericidal effect is expressed as the difference between the initial total bacterial count in the untreated group and the total bacterial count after treatment in each group. The actual logarithmic reduction values ​​in Table 2 are the same as those in Table 2. Figure 1 The initial total number of colonies in the untreated group (Log) 10 N0) and the total number of colonies after each treatment group (Log) 10 The difference of N) represents the expected logarithmic decrease in Examples 1 and 7, which are the sum of the actual logarithmic decreases of Comparative Examples 1 and 3, and the sum of the actual logarithmic decreases of Comparative Examples 2 and 4, respectively. The ratio is the ratio of the actual logarithmic decrease to the expected logarithmic decrease. When the ratio is greater than 1, a synergistic effect is considered to exist.

[0143] Depend on Figure 1 Comparative test results show that as the low-temperature plasma conditions are increased from a discharge frequency of 25 kHz, a discharge voltage of 40 kV, and a discharge time of 60 s to 30 kHz, a discharge voltage of 50 kV, and a discharge time of 120 s, the sterilization effect of single plasma treatment increases from 0.82 (Log0.05) to 0.82 (Log0.05). 10 CFU / g increased to 1.19 (Log) 10 CFU / g; as the EGCG treatment conditions were increased from a concentration of 0.05% and a treatment time of 10 min to a concentration of 0.10% and a treatment time of 15 min, the bactericidal effect of single EGCG treatment increased from 0.39 (Log0.05 CFU / g); 10CFU / g increased to 0.56 (Log) 10 CFU / g. Meanwhile, from Figure 1 The changes in sterilization effect in the examples show that with the increase of treatment intensity (increased low-temperature plasma discharge frequency, discharge voltage, and discharge time; increased EGCG concentration and treatment time; and decreased treatment temperature), the sterilization effect of the combined treatment is significantly enhanced. The sterilization effect of Example 2, representing the upper boundary, is 2.25 (Log). 10 ) CFU / g., representing the lower boundary, Example 1 is 1.43 (Log 10 ) CFU / g.

[0144] As shown in Table 2, the actual logarithmic decrease in Example 1 was 0.21 higher than expected. 10 CFU / g, Example 7: Actual logarithmic decrease increased by 0.41 (Log) compared to expectations. 10 The result of CFU / g indicates that the combined treatment with low-temperature plasma and EGCG has a synergistic effect in sterilization compared to single low-temperature plasma and EGCG treatment. Furthermore, the ratio of actual to expected reduction in Example 7 is greater than that in Example 1, indicating that the synergistic effect is enhanced as the intensity of the low-temperature plasma and EGCG treatment increases.

[0145] The national food safety standard GB 2726-2016 sets a limit of 10 μg / L for the total bacterial count in cooked meat products. 5 CFUg -1 This limit quantifies food safety risks and is also an important indicator for predicting product shelf life. Figure 2 The results showed that the untreated group exceeded the limit by approximately 10 after about 4 days of storage. 5 CFU g -1 The limits were exceeded by low-temperature plasma treatment, EGCG immersion treatment, and low-temperature plasma combined with EGCG treatment, which only exceeded the limits on approximately day 6, day 11, and day 18, respectively. This indicates that the combined treatment had a better sterilization effect, improved the preservation effect of salt-baked chicken during storage, and extended its shelf life.

[0146] Table 2 Synergistic effect of low-temperature plasma and EGCG on total bacterial count under different conditions ;

[0147] TVB-N value test:

[0148] Referring to the National Food Safety Standard GB 5009.228-2016 (Determination of Volatile Basic Nitrogen in Food), with slight modifications, 15 g of lean, tendon-free salt-baked chicken was minced and soaked in 100 mL of distilled water for 30 min, shaking occasionally during soaking. The extract was filtered, and 20 mL of filtrate and magnesium oxide were added to the distillation tube, which was then immediately connected to the still. The Kjeldahl nitrogen analyzer was set to automatically add 0 mL of alkali, 0 mL of water, and 30 mL of boric acid receiving solution, with a distillation time of 180 s. After distillation, 10 drops of a 1:5 mixture of methyl red ethanol and bromocresol green ethanol indicator were added to the conical flask, and titrated with 0.01 M hydrochloric acid standard solution. The endpoint color was pale pink. Calculation formula: ;

[0149] In the formula, X is the nitrogen content, in mg / 100 g; V1 is the volume of hydrochloric acid titrant consumed by the reagent, V2 is the volume of hydrochloric acid titrant consumed by the blank test, in mL; c is the concentration of hydrochloric acid titrant, in M; 14 is a constant; m is the sample mass, in g; 0.2 is the proportion of the filtrate volume in the total sample volume; 100 is the conversion factor.

[0150] TVB-N is an alkaline nitrogenous compound with an unpleasant odor produced during protein decomposition in food. Its content is influenced by the growth and reproduction of spoilage-causing microorganisms and the activity of their own enzymes. The national food safety standard GB 2707-2016 sets the TVB-N limit for frozen poultry products at 15 mg per 100 g. -1 A lower TVB-N value indicates less protein breakdown and fresher meat. (15 mg / 100 g) -1 The limits quantify the freshness and acceptable quality of meat products. The test results of the examples and comparative examples are as follows: Figure 3 As shown, the untreated group reached the limit at approximately day 12 of storage, the low-temperature plasma-treated group reached the limit at approximately day 18 of storage, while the TVB-N values ​​of the EGCG-treated group and the low-temperature plasma combined with EGCG-treated group were 10.58 mg / 100g at day 18 of storage. -1 7.93 mg 100 g -1 All values ​​were within the limit, indicating that although the total bacterial count of the salt-baked chicken exceeded the limit, it had not yet spoiled. Meanwhile, the TVB-N value of the low-temperature plasma combined with EGCG treatment group was significantly lower than that of the EGCG treatment group (p < 0.05), indicating that the combined treatment better delayed the increase in TVB-N value.

[0151] TBARS value test:

[0152] Referring to the National Food Safety Standard GB 5009.181-2016 (Determination of Malondialdehyde in Food), with slight modifications, 2 g of salt-baked chicken was weighed and mixed with 3 mL of 1% thiobarbituric acid solution (dissolved in 0.075 mol / L NaOH) and 17 mL of TCA-HCl solution (2.5% TCA, 0.04 mol / L HCl). Then, 0.5 mL of 0.19 mol / L 2,6-di-tert-butyl-p-cresol (BHT) solution was added. The mixture was reacted in a boiling water bath for 30 min, and then cooled to room temperature. 5 mL of the suspension was mixed with 5 mL of chloroform and vortexed for 1 min, then centrifuged at 3000 r / min for 10 min. The supernatant was collected and the absorbance was read at 532 nm. Calculation formula:

[0153]

[0154] Where: TBARS is the number of milligrams of malondialdehyde per liter of sample solution, mg MDA⋅kg -1 A 532 The absorbance of the sample was measured at 532 nm; W s is the sample mass, in g; 9.48 is a constant.

[0155] TBARS values ​​are commonly used to indicate the secondary products of unsaturated fatty acid oxidation and are one of the core indicators for evaluating fat oxidation and freshness in meat. The test results of the examples and comparative examples are as follows: Figure 4 As shown, the TBARS value increased in the low-temperature plasma treatment group compared to the untreated group, indicating intensified lipid oxidation. This may be due to the interaction of reactive oxygen species generated under a high-voltage electric field with the fat in chicken meat, catalyzing the formation of lipid oxidation byproducts (such as hexanal and malondialdehyde). As a natural antioxidant, EGCG has a unique polyphenol structure, and its hydroxyl groups can effectively scavenge free radicals and interrupt the oxidation chain reaction. Compared to the untreated group, EGCG treatment effectively reduced the TBARS value. On day 0, the TBARS values ​​of the EGCG group and the low-temperature plasma combined with EGCG treatment group were 0.53 mg / kg and 0.56 mg / kg, respectively, with no significant difference (p > 0.05), indicating that the plasma parameters of Example 7 did not damage the antioxidant properties of EGCG.

[0156] During storage, the TBARS values ​​of the low-temperature plasma and EGCG combined treatment group were significantly lower than those of the EGCG single treatment group. On days 0, 6, 12, and 18, the differences between the two groups were 0.03 mg / kg, 0.28 mg / kg, 0.43 mg / kg, and 0.46 mg / kg, respectively, indicating that the low-temperature plasma and EGCG combined treatment has a synergistic inhibitory effect on lipid oxidation. This may be because the microstructure pores formed on the surface of the chicken by plasma treatment may enhance the penetration of EGCG into the interior, thereby enhancing the inhibition of lipid oxidation.

[0157] Hardness test:

[0158] The hardness of salt-baked chicken before and after treatment was measured using a TA.XT plus C texture analyzer. The probe was a P36 cylindrical probe. The speed before testing was 1.9 mm / s, the testing speed was 1 mm / s, and the speed after testing was 1.9 mm / s. The compression ratio was 30%, and the interval between two tests was 5 s. Table 3 shows that there was no significant difference in hardness among the groups, and the change with the number of days was also not significant (p > 0.05). With increasing storage days, the overall hardness of all groups decreased, possibly due to increased spoilage and the decomposition of structural proteins in the meat, leading to a looser texture. On day 18 of storage, the group treated with the combined low-temperature plasma and EGCG showed the highest hardness value, indicating that the hardness was well maintained.

[0159] Table 3. Effects of different treatment conditions on the hardness changes of salt-baked chicken during storage. ;

[0160] Note: A, for the same storage days, different capital letters indicate significant differences between treatment groups (p < 0.05); a, within the same treatment group, different lowercase letters indicate significant differences at different storage times (p < 0.05).

[0161] Colorimetric value test:

[0162] After calibration with a standard white board, the color values ​​of the salt-baked chicken before and after treatment were detected using a CR-400 colorimeter. Each sample was tested 5 times at different locations and the average value was taken.

[0163] As shown in Table 4-6, single low-temperature plasma treatment, EGCG treatment, and combined low-temperature plasma and EGCG treatment all reduced the initial L* value by 8.80, 9.16, and 7.35, respectively. However, with the increase of days, the L* value of each group was greater than that of the untreated group, thus slowing down the further decrease of the L* value.

[0164] On day 0, the a* value of the untreated group was 3.18, which was reduced to 1.73 by EGCG treatment alone, resulting in a whiter meat texture. The a* value of the group treated with a combination of low-temperature plasma and EGCG was 2.67, higher than the EGCG-only group, indicating that the combined treatment with low-temperature plasma and EGCG can reduce the adverse effects of EGCG aqueous solution soaking on the redness value of salt-baked chicken. The b* value showed no significant change. The combined treatment with low-temperature plasma and EGCG effectively maintained the color of the salt-baked chicken during storage.

[0165] Table 4. Effects of different treatment conditions on the change of L* value of salt-baked chicken during storage. ;

[0166] Table 5. Effects of different treatment conditions on the changes in a* value of salt-baked chicken during storage. ;

[0167] Table 6. Effects of different treatment conditions on the change of b* value of salt-baked chicken during storage. ;

[0168] Note: A~D, under the same storage days, different uppercase letters indicate significant differences between treatment groups (p < 0.05); a~d, within the same treatment group, different lowercase letters indicate significant differences at different storage times (p < 0.05).

[0169] This invention addresses the technical shortcomings of using low-temperature plasma technology alone in processing meat products like salt-baked chicken. While effective in sterilization, it can induce lipid oxidation, leading to deterioration in product color and nutritional quality. The invention discovers that combining low-temperature plasma treatment with EGCG treatment can effectively leverage the high sterilization efficiency of low-temperature plasma while simultaneously inhibiting its oxidative degradation effects. The test results above effectively demonstrate this finding. This invention, based on a method for improving the edibility and safety of salt-baked chicken using low-temperature plasma and EGCG treatment, is expected to maximize the preservation of its sensory and nutritional qualities while ensuring the microbial safety of salt-baked chicken, thereby improving the industrial production quality of salt-baked chicken and promoting technological progress in the industry.

[0170] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the palatability and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment, characterized in that: Fresh chicken is used as raw material. After cleaning, removing hair, fat and tendons, it is marinated with salt and cooking wine, then braised in prepared braising liquid. After being treated by dielectric barrier discharge type low-temperature plasma equipment and soaked in EGCG solution, it is vacuum packaged and refrigerated. The electric field discharge frequency of the dielectric barrier discharge type low-temperature plasma equipment is controlled at 25-35 kHz and the discharge voltage is controlled at 40-60 kV. The EGCG solution soaking treatment uses an EGCG aqueous solution with a mass concentration of 0.05-0.15% and a soaking time of 10-15 min.

2. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The discharge time of the dielectric barrier discharge type low-temperature plasma device is 60-180 s.

3. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The electric field discharge frequency of the dielectric barrier discharge type low-temperature plasma device is 25-30kHz.

4. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The discharge voltage of the dielectric barrier discharge type low-temperature plasma device is 40-50 kV.

5. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The discharge of the dielectric barrier discharge type low-temperature plasma device is carried out at room temperature, with air as the working gas.

6. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The EGCG immersion treatment was carried out at a temperature of 4-30℃.

7. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The mass ratio of EGCG to salt-baked chicken is 1:400-3:

400.

8. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The marinating time is 2-4 hours; the braising time is 20-30 minutes.

9. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The refrigerated storage temperature is 4-8℃, and the storage time is within 18 days.

10. The method for improving the edibility and safety of salt-baked chicken based on low-temperature plasma and EGCG treatment according to claim 1, characterized in that: The braising temperature is 90-95℃, and the braising time is 20-30 minutes.

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