Pickling liquid based on plasma activated water and salicornia europaea plant salt and application of pickling liquid in low-salt air-dried goose processing

Abstract

The invention discloses a pickling liquid based on plasma activated water and salicornia europaea plant salt and application of the pickling liquid in low-salt air-dried goose processing, and is characterized in that the pickling liquid is obtained by dissolving sodium chloride and salicornia europaea plant salt in the plasma activated water; the pickling solution is a plasma activated water mixed solution containing 4-7.2 wt% of sodium chloride and 0.8-4 wt% of salicornia europaea plant salt, and the preparation method of the low-salt air-dried goose further comprises the step of treating pure water by adopting plasma jet equipment taking air as carrier gas to obtain treated plasma activated water. The green low-salt air-dried goose has the advantages that the usage amount of NaCl can be effectively reduced, the salty taste of the air-dried goose is not reduced, meanwhile, the color and luster of the goose are better kept, the taste of the product is improved, the taste is improved, and fat oxidation rancidity is inhibited.

Description

Technical Field

[0001] The invention relates to a method for processing low-salt air-dried goose, in particular to a pickling liquid based on plasma-activated water and samphire plant salt and application of the pickling liquid in the processing of low-salt air-dried goose. Background Art

[0002] Sodium chloride (NaCl) is a commonly used additive in food processing. During the processing of traditional air-dried meat products such as dry-cured ham, air-cured duck, air-dried goose, and air-dried sausage, large amounts of NaCl are required to maintain the texture and color of the meat products and prevent spoilage. Long-term consumption of high-salt foods can lead to conditions such as high blood pressure and blood vessel blockage. Air-dried goose is a traditional Chinese cured and air-dried food, originating in southern China and certain specific regions. It is mainly produced through an air-drying process. The finished goose meat has a rich flavor and a chewy texture. However, traditional air-dried goose processing has several drawbacks, such as uneven drying, inadequate curing, and high salt usage, which affect its quality and safety. Therefore, there is an urgent need to develop salt-reducing curing methods to replace traditional NaCl in the production of air-dried goose products. Currently, common methods for reducing salt in foods include vacuum curing, high-pressure curing, pulse curing, gamma irradiation, potassium salts, calcium salt substitution, and plant salt substitution. Vacuum curing and other methods are difficult to implement due to issues with the compatibility of equipment and raw materials. While hollow salt can reduce salt intake, widespread adoption is likely to be difficult due to taste differences, low acceptance, high costs, and uncertain effectiveness. Therefore, the development of a new, green, air-dried meat processing technology that reduces salt, stabilizes saltiness, and improves quality is urgent.

[0003] Plant salts are gaining attention as an emerging green food. Their potential as a replacement for traditional table salt lies in their rich natural minerals, aroma, flavor, and more sustainable sources. Key plant alternatives include seaweed (such as kelp, laver, and nori), herbs and spices (such as rosemary, garlic, and thyme), bitter plants (such as chicory), and salt-containing plants (such as salt leaves). These plants provide a natural salty flavor and are rich in trace elements (such as potassium, calcium, and magnesium), which can reduce sodium intake and pose lower health risks. Salicornia spp. is considered an effective salt-reducing agent. The mechanism of action of Salicornia spp. as a NaCl substitute can be explained from two perspectives. First, Salicornia spp. is rich in naturally occurring minerals such as sodium, calcium, and magnesium. These components stimulate salt receptors on the tongue, producing a salty taste. Despite its low sodium content, Salicornia spp., through its balanced mineral content, effectively imparts a salty flavor, resulting in a mouthfeel similar to that of table salt. Secondly, using Salicornia herba as a replacement for NaCl can improve the structure of meat products and promote a "salt permeation" effect. These components, by stimulating taste receptors, can enhance the perception of other flavors, particularly umami and seafood, further heightening the salty taste. Furthermore, Salicornia herba grows on non-agricultural land, such as saline-alkali soils, conserves water and tolerates drought, making it highly sustainable. Using Salicornia herba can reduce dependence on traditional table salt. Therefore, developing Salicornia herba salt as a new green salt-reduction technology for food processing meets the demand for low-salt, healthy foods in the modern food industry.

[0004] Since the sea lily plant salt contains a large amount of plant powder tissue, using the sea lily plant salt alone to replace NaCl may lead to unsatisfactory curing effect of air-dried goose, thus affecting the improvement of taste and flavor. Therefore, there is an urgent need for an effective physical processing method to make up for this deficiency, so as to comprehensively improve the overall quality of air-dried goose. In recent years, plasma-activated water (PAW) has gradually attracted attention as a green food processing technology. PAW activates water molecules through plasma discharge, making the water rich in active nitrogen oxides (such as NO2 - 、H2O2、O2 - ), can affect the composition of proteins, lipids, and flavor compounds in the food matrix during meat curing. During meat processing, PAW may promote protein degradation, improve meat texture, and increase free amino acid content, thereby enhancing the flavor of cured meat products. Furthermore, PAW has certain antimicrobial properties, which can improve food safety. Currently, there are no reports on low-salt air-dried goose processing methods based on co-curing with plasma-activated water and Salicornia herbacea salt. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a pickling liquid based on plasma-activated water and samphire plant salt, which can effectively reduce the amount of NaCl used without reducing the saltiness of air-dried goose, while better maintaining the color of goose meat, enhancing the product flavor, improving the mouthfeel, and inhibiting fat oxidation and rancidity, and the application of the pickling liquid in low-salt air-dried goose processing.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a pickling liquid based on plasma-activated water and samphire plant salts, wherein the pickling liquid is obtained by dissolving sodium chloride and samphire plant salts in plasma-activated water, and the pickling liquid is a plasma-activated water mixture containing 4-7.2wt% of sodium chloride and 0.8-4wt% of samphire plant salts.

[0007] Furthermore, the pickling liquid is a plasma-activated water mixture containing 4.8 wt % of sodium chloride and 3.2 wt % of Salicornia herbacea plant salt.

[0008] Furthermore, the preparation method of the plasma-activated water is as follows: pure water is treated using a plasma jet device with air as the carrier gas, the gas flow rate is set to 28-32 L / min, the power is set to 680-700 W, and the treatment time is set to 5-15 minutes, and the treated plasma-activated water can be obtained.

[0009] The present invention also provides application of the pickling liquid in preparing low-salt air-dried goose.

[0010] Furthermore, the preparation method of the low-salt air-dried goose comprises the following steps:

[0011] Step 1: Treat pure water with a plasma jet device using air as a carrier gas to obtain treated plasma-activated water;

[0012] Step 2: Immerse the washed goose meat in the pickling solution according to any one of claims 1 to 3, pickle it at a ratio of 1000 to 2000 mL of pickling solution per kilogram of goose meat, and then air-dry it to obtain green low-salt air-dried goose.

[0013] Furthermore, step 1 is specifically as follows: pure water is treated with a plasma jet device using air as a carrier gas, the gas flow rate is set to 28-32 L / min, the power is set to 680-700 W, and the treatment time is set to 5-15 minutes, so as to obtain treated plasma-activated water.

[0014] Furthermore, the pickling liquid in step 2 is a plasma-activated water mixture containing 4.8 wt % of sodium chloride and 3.2 wt % of Salicornia herbacea plant salt.

[0015] Furthermore, the curing temperature of the air-dried goose described in step 2 is 0-4° C., and the curing time is 24 hours.

[0016] Furthermore, the air-drying temperature of the air-dried goose in step 2 is 14-18° C., the relative humidity is 65-70%, and the air-drying time is 2-4 days.

[0017] Compared with the prior art, the advantages of the present invention are: the present invention provides a pickling solution based on plasma-activated water and Salicornia herba plant salt and its application in the processing of low-salt air-dried goose, by optimizing the replacement ratio of Salicornia herba plant salt to sodium chloride, and combining plasma-activated water (PAW) treatment technology, under the premise of significantly reducing the amount of pickling salt, effectively improving the taste quality and overall quality of air-dried goose meat. Through the activation effect of PAW, the degradation of protein in meat is significantly promoted, the activity of endogenous proteases such as Cathepsin is increased, and the degree of unwinding of myofibrillar protein is enhanced, thereby promoting the production of free amino acids, especially the content of umami and sweet amino acids (such as glutamic acid, aspartic acid, alanine, etc.) is significantly improved, directly enhancing the umami and flavor fullness of the product. At the same time, Salicornia herba plant salt is rich in minerals, has a good salty taste compensation effect on the replacement of NaCl, and also cooperates with PAW to improve the water holding capacity and texture characteristics of the product, so that the product has enhanced elasticity in texture and better taste. Sensory evaluation results show that this method outperforms conventional low-salt curing methods in terms of umami, sweetness, chewiness, and overall acceptability, resolving the issues of insufficient flavor and rough texture in existing low-salt meat products. The invention utilizes natural and safe raw materials and a simple processing technique, demonstrating its applicability and potential for industrial promotion.

[0018] In summary, the present invention provides a method for processing low-salt air-dried goose by co-curing with plasma-activated water and samphire salt. Curing the goose with PAW promotes protein degradation, improves goose texture, and facilitates the penetration of the samphire salt. The combined effect of these two methods reduces the NaCl content while maintaining saltiness, enhancing the mouthfeel and flavor of the air-dried goose. This method is environmentally friendly, improves flavor and mouthfeel, and reduces NaCl content, providing technical support for the industrialized production of low-salt air-dried meat products. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Figure 3: Electronic tongue taste test and actual human sensory evaluation results of air-dried geese obtained under different treatment methods; A shows the actual sensory evaluation results (SS1-SS7) of air-dried geese after preliminary screening of different proportions of NaCl replaced by Salicornia herba plant salt; B shows the actual sensory evaluation results of air-dried geese under different treatment groups; C shows the electronic tongue measurement of saltiness intensity of air-dried geese under different treatment groups;

[0020] Figure 2The effects of different curing methods on the moisture distribution of air-dried geese; A is the determination of water holding capacity of air-dried geese in different treatment groups, B is the determination of moisture content of air-dried geese in different treatment groups, C is the determination of moisture distribution of air-dried geese in different treatment groups, and D is the determination of peak areas of each component in moisture distribution of air-dried geese in different treatment groups.

[0021] Figure 3 The effects of different pickling methods on the activity of endogenous proteases in air-dried geese; A is the activity of cathepsin B in air-dried geese of different treatment groups, B is the activity of cathepsin L in air-dried geese of different treatment groups, C is the activity of cathepsin H in air-dried geese of different treatment groups, D is the activity of dipeptidase I and dipeptidase IV in air-dried geese of different treatment groups, and E is the activity of alanine amidopeptidase in air-dried geese of different treatment groups;

[0022] Figure 4 To study the effects of different curing methods on the hydrolysis degree of air-dried goose protein;

[0023] Figure 5 Effects of different curing methods on pH (A) and TBARS (B) of air-dried goose. DETAILED DESCRIPTION

[0024] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments. 1. Specific embodiments

[0026] Example 1: A method for processing low-salt air-dried goose by co-curing with plasma-activated water and samphire plant salt, comprising the following steps:

[0027] Step 1: Place 500 mL of pure water in a beaker and treat it using a plasma jet device with air as the carrier gas. Set the gas flow rate to 28-32 L / min, the power to 680-700 W, and the treatment time to 10 min to obtain treated plasma-activated water (PAW).

[0028] Step 2: Sodium chloride and Salicornia herbacea salt are added to plasma-activated water to obtain a curing solution, and the washed goose meat is immersed in the curing solution. The goose meat is cured at a rate of 1500 mL of curing solution per kilogram of goose meat, and then air-dried to obtain a green low-salt air-dried goose. The curing solution is a mixture containing 4.8 wt% sodium chloride and 3.2 wt% Salicornia herbacea salt, which is designated as SS6 (SAL-PAW group: PAW + NaCl 4.8% + Salicornia herbacea salt 3.2%).

[0029] Example 2 is the same as Example 1, except that the pickling liquid is a mixture containing 7.2 wt % of sodium chloride and 0.8 wt % of Salicornia herbacea plant salt, denoted as SS3.

[0030] Example 3 is the same as Example 1, except that the pickling liquid is a mixture containing 6.4 wt% of sodium chloride and 1.6 wt% of Salicornia herba plant salt, denoted as SS4.

[0031] Example 4 is the same as Example 1, except that the pickling liquid is a mixture containing 5.6 wt % of sodium chloride and 2.4 wt % of Salicornia herbacea plant salt, denoted as SS5.

[0032] Example 5 is the same as Example 1, except that the pickling liquid is a mixture containing 4 wt% sodium chloride and 4 wt% of Salicornia herba plant salt, denoted as SS7.

[0033] Comparative Example 1: Sodium chloride was added to pure water to obtain a curing solution with a NaCl mass percentage of 8%. The washed goose meat was immersed in the curing solution for curing. The washed and drained goose meat was marinated at a rate of 1500 mL of curing solution per kilogram of goose meat, and then air-dried to obtain air-dried goose, which was recorded as SS1 (control group CK: pure water + NaCl 8%).

[0034] Comparative Example 2: Sodium chloride was added to plasma-activated water to obtain a curing solution with a NaCl mass percentage of 8%. The washed goose meat was immersed in the curing solution for curing. The washed and drained goose meat was marinated at a rate of 1500 mL of curing solution per kilogram of goose meat and then air-dried to obtain air-dried goose, designated as SS2 (PAW group: PAW + NaCl 8%).

[0035] Comparative Example 3: Sodium chloride and samphire plant salt were added to pure water to obtain a curing liquid, and the washed goose meat was immersed in the curing liquid for curing. The washed and drained goose meat was marinated at a rate of 1500 mL of curing liquid per kilogram of goose meat, and then air-dried to obtain a green low-salt air-dried goose, wherein the curing liquid was a mixture containing 4.8 wt% of sodium chloride and 3.2 wt% of samphire plant salt, recorded as the SAL group: pure water + NaCl 4.8% + samphire plant salt 3.2%.

[0036] 2. Analysis of experimental results.

[0037] 1. Sensory evaluation of air-dried geese with different treatments and electronic tongue test results

[0038] The pre-treated goose meat was marinated in different curing solutions. After marinating for 24 hours, the meat was drained and placed in an air dryer for drying. The air-drying process employed a temperature of 16°C, a humidity of 68%, and air-drying for 72 hours. After air-drying, the air-dried goose meat was removed and steamed in water at 100°C for 0.5 hours before being sliced ​​into thin slices. Ten food sensory professionals were recruited to rate the air-dried goose samples for bitterness, off-flavor, saltiness, umami, texture, and overall acceptability. Each panelist conducted the evaluation individually, with no communication between panelists. Panelists were required to rinse their mouths between samples to eliminate intergroup interference. The ratings were scored on a 9-point scale, with 9 indicating very satisfied and 1 indicating very dissatisfied.

[0039] Ten grams of air-dried goose sample was mixed with 50 mL of 40°C distilled water. After homogenization at 12,000 rpm for 1 minute, the mixture was centrifuged at 3,000 g for 10 minutes. The supernatant was collected and placed in the solution for taste testing using an electronic tongue taste sensor. NaCl solutions at concentrations of 0.1%, 0.3%, and 0.5% were used as salty standards and controls.

[0040] like Figure 1 As shown in Figure A, the sensory radar chart shows that the saltiness of the SS2 group is higher than that of the SS1 group, indicating that PAW curing enhances saltiness in the human taste experience, likely due to changes in the meat's texture. As the NaCl ratio gradually decreases and the salt content of the Salicornia herb increases, the saltiness decreases, reaching a level similar to that of the SS6 group. Other indicators demonstrate that PAW significantly enhances the sensory experience and overall acceptability. Sensory evaluations of different replacement ratios show that the SS4 group is well-received by consumers, both in terms of reducing the sodium chloride ratio and overall acceptability.

[0041] like Figure 1 As shown in Figure B, sensory evaluation results show that the SAL group showed a slight decrease in saltiness compared to the control group (CK). This is because the same amount of Salicornia plant salt is less salty than sodium chloride, indicating that Salicornia plant salt can compensate for the loss of saltiness caused by the reduction of sodium chloride, but cannot completely replace it. At the same time, freshness and taste scores improved, demonstrating the effectiveness of reducing salt and increasing freshness. However, the overall effect was still inferior to the control group. The PAW group cured with plasma-activated water (PAW) showed a slight increase in saltiness, reduced off-flavor, and improved overall acceptability. Combining SAL with PAW maintained similar saltiness compared to the control group, but significantly improved umami, taste, and overall acceptability. This is primarily because curing with plasma-activated water loosens the myofibril structure, making it easier for salt to penetrate. Overall, combining SAL with PAW significantly improves the sensory attributes and physicochemical quality of meat.

[0042] like Figure 1 As shown in Figure C, the electronic tongue saltiness graph shows that the saltiness of the Salicornia herbacea plant salt deviated significantly from that of the CK control group and decreased compared to the salty standard, indicating that some saltiness was lost during processing. The saltiness of the PAW and SAL-PAW groups was similar to that of the CK group, a result consistent with the sensory evaluation.

[0043] 2. Effects of different treatments on the texture, water holding capacity, moisture content and low-field nuclear magnetic resonance (LF-NMR) of air-dried goose

[0044] (1) Texture analysis: Texture analysis TPA was performed using a TA-XTplus mass analyzer equipped with a cylindrical probe (P / 50, 50 mm in diameter). The goose meat was cut into 2 cm × 2 cm × 2 cm cubes. The following conditions were used for analysis: pre-test speed 2.00 mm / s; trigger force 5 g; test speed 1.00 mm / s; post-test speed 1.00 mm / s. The data acquisition rate was 200 pps. The hardness, elasticity, viscosity and chewiness of the goose meat in the different salt replacement groups were measured. Each group was tested 3 times and the average value was taken. The results are shown in Table 1.

[0045] Table 1 Texture determination results of air-dried goose obtained by different curing methods

[0046]

[0047] Note: In the table, ac: different letters indicate significant differences among different treatment groups (p<0.05).

[0048] As shown in Table 1, the results of this study indicate that low-salt treatment (SAL group) significantly reduced the product's hardness (P < 0.05) by regulating endogenous enzyme activity, promoting proteolysis, and altering the myofibrillar protein network structure, while also improving its elasticity and softness. Notably, the plasma-activated water (PAW) treatment group, rich in nitrogen oxides, may have accelerated myofibrillar protein degradation by activating cathepsin activity, thereby effectively improving the tenderness of air-dried goose products. When SAL and PAW form a synergistic treatment system, they jointly act on protein structure modification through salt ion regulation and the mediation of bioactive ingredients, not only significantly optimizing the product's texture properties but also forming a unique taste profile. This innovative process, based on the synergistic effect of salt replacement and PAW, provides an important technical reference for modernizing the quality of traditional air-dried meat products.

[0049] (2) Water-holding capacity: First, weigh the centrifuge tube (m1). Place 2 g of goose meat in the centrifuge tube and weigh both together (m2). Immediately place the weighed sample in a centrifuge and centrifuge at 8000 rpm for 10 min at 4°C. After discarding the supernatant, weigh the centrifuge tube containing the goose meat (m3). Calculate the water-holding capacity using the following equation: Water-holding capacity (%) = (m3 - m1) / (m2 - m1) * 100.

[0050] like Figure 2 As shown in Figure A, the water-holding capacity of the SAL, PAW, and SAL-PAW groups was significantly improved compared to the control group, CK. This indicates that the treatment significantly improved the product's texture, specifically by reducing hardness and increasing elasticity. This improves the dry and tough texture of traditional air-dried goose and enhances its tenderness and juiciness. The combined SAL-PAW treatment achieved even greater results. Previous studies have shown a positive correlation between water-holding capacity and the proteolysis index, further confirming the effectiveness of this treatment.

[0051] (3) Moisture content determination: Take 2g of air-dried goose sample and place it on a moisture content meter at 105℃ until the sample is completely evaporated. The ratio of the difference in sample mass before and after measurement to the sample mass before measurement is the moisture content of the sample.

[0052] like Figure 2 As shown in Figure B, the moisture content of the SAL, PAW, and SAL-PAW groups all increased significantly, with the SAL group showing a more pronounced effect. This trend is consistent with the water-holding capacity indicator. Increasing moisture content also improves the taste and flavor of air-dried goose meat, retains nutrients, and makes it more popular with consumers.

[0053] (4) Determination of moisture distribution and proportion in air-dried goose samples using a low-field nuclear magnetic resonance analyzer: After instrument calibration, 4 g of sample was placed in a 25 mm NMR tube, and the spin-spin relaxation time (T2) was measured using a Carr-Purcell-Meibo-Gill (CPMG) pulse sequence. Typical pulse parameters were set as follows: spectral width of 200 kHz, wait time of 1500 ms, RF delay time of 0.002 ms, 16 scans, 10,000 echoes, and an echo time of 0.4 ms.

[0054] like Figure 2 Middle C and Figure 2As shown in Figure D, low-field nuclear magnetic resonance (NMR) technology revealed the highest and most variable levels of immobile water across all groups. Compared to the control group (CK), the immobile water content in the treated groups was significantly increased (p < 0.05). This indicates that structural changes, combined with the effects of the samphire, increase the water content within the myofibrils. Compared to free water, the presence of immobile water allows meat products to release an appropriate amount of water during chewing, improving the taste and making them more tender and juicy.

[0055] 3. Effects of different treatments on protease activity of air-dried goose myofibrillar protein

[0056] Cathepsin activity assay: 0.5 g of air-dried goose sample was accurately weighed and added with 2.5 mL of 50 mM sodium citrate buffer (containing 0.2% Triton X-100 and 1 mM ethylenediaminetetraacetic acid (EDTA), pH 5.0). The sample was homogenized three times at 12,000 rpm on ice for 10 s each time. The sample was then centrifuged at 12,000 g for 20 min at 4°C. The supernatant was collected and filtered for the activity of cathepsins B, L, and H. Protein concentration in the supernatant was determined using a BCA protein assay kit. N-CBZ-Arg-Arg-AMC, L-Arg-AMC, and N-CBZ-phe-Arg-AMC were used as substrates for the activity assays of cathepsins B, H, and B+L, respectively. One unit of enzyme activity (U) was defined as the amount of enzyme required to produce 1 nmol of 7-amino-4-methylcoumarin (AMC) per minute per mg of protein at 37°C.

[0057] To determine dipeptidyl peptidase I (DPP I) activity, 2 g of muscle sample, free of visible fat and connective tissue, was added to 20 mL of 100 mM sodium acetate buffer (pH 5.5) and homogenized three times at 10,000 rpm for 10 seconds each at 4°C. The homogenate was centrifuged at 12,000 g for 20 minutes at 4°C, and the supernatant was collected and filtered. Protein content in the filtered supernatant was determined using a BCA protein assay kit. DPP I activity was also determined using a fluorogenic substrate assay. The reaction mixture consisted of 100 μL of enzyme extract, 100 μL of 100 mM sodium acetate buffer containing 5 mM DTT, and 0.5 mM Gly-Arg-AMC. The enzyme extract and fluorogenic substrate mixture was added to a 96-well plate and incubated at 37°C for 30 minutes. Fluorescence was measured at λex = 355 and 460 nm. One unit of enzyme activity (U / mg protein) is defined as the amount of enzyme required to hydrolyze 1 nmol of substrate per mg of protein per minute at 37°C.

[0058] Dipeptidase IV (DPPIV): 2 g of muscle sample, free of visible fat and connective tissue, was added to 20 mL of 100 mM sodium phosphate buffer (pH 7.5) and homogenized three times at 10,000 rpm for 10 seconds each at 4°C. The homogenate was centrifuged at 12,000 g for 20 minutes at 4°C, and the supernatant was collected and filtered. Protein content in the filtered supernatant was determined using a BCA protein assay kit. DPPIV activity was also determined using a fluorogenic substrate assay. The reaction mixture consisted of 100 μL of enzyme extract, 50 mM Tris-HCl buffer (containing 5 mM DTT, pH 8.0), and 0.5 mM Gly-Pro-AMC. The reaction mixture containing the enzyme extract and fluorogenic substrate was added to a 96-well plate and incubated at 37°C for 30 minutes. Fluorescence was measured at λex = 355 and λex = 460 nm. One unit of enzyme activity (U / mg protein) was defined as the amount of enzyme required to hydrolyze 1 nmol of substrate per mg of protein per minute at 37°C.

[0059] Alanyl aminopeptidase activity assay: 2 g of meat (without visible fat or connective tissue) was minced and suspended in 20 mL of 50 mM phosphate buffer (containing 5 mM ethylene glycol tetraacetic acid (EGTA, pH 7.5)). Homogenize the mixture three times at 12,000 rpm for 10 seconds each at 4°C. The homogenate was then centrifuged at 12,000 g for 20 minutes at 4°C, and the supernatant was collected and filtered. The protein content of the filtered supernatant was determined using a BCA protein assay kit. Alanyl aminopeptidase activity was determined using a specific substrate assay with 0.5 mM alanyl-AMC.

[0060] The alanyl aminopeptidase activity assay system consists of 150 μL of enzyme extract, 100 μL of 50 mM sodium dihydrogen phosphate buffer (pH 6.5), 2 mM β-mercaptoethanol, and 0.5 mM alanyl-AMC. The enzyme-substrate mixture is incubated at 37°C for 30 min. Alanyl aminopeptidase activity is measured at λex = 355 and λem = 460 nm, respectively. Each aminopeptidase activity assay is performed in triplicate. One unit (U) of enzyme activity is defined as the amount of enzyme required to hydrolyze 1 nmol of substrate per minute per mg of protein at 37°C.

[0061] Changes in muscle protease activity, especially cathepsin B, cathepsin L, dipeptidase, and aminopeptidase, are key determinants of the sensory and flavor quality of dry-cured ham. Cathepsins B and L are considered to be the main proteases that contribute to protein degradation and flavor formation in dry-cured ham. Figure 3 Middle A, Figure 3 Middle B and Figure 3As shown in Figure C, compared with the control group, all treatment groups significantly increased the enzymatic activity of cathepsin B+L, while no statistical difference was observed in the activity of cathepsin H. It is speculated that the difference in cathepsin H may be due to the stronger binding properties of cathepsin H in the muscle matrix, which makes it difficult to be released.

[0062] In the protein degradation system, dipeptidase I and IV are key hydrolases, and their activity levels directly affect the efficiency of protein degradation and the generation of flavor precursors. Figure 3 As shown in Figure D, the activities of dipeptidase I in the PAW group and SAL-PAW group were increased by 25.25% and 37.64% respectively compared with the control group, while the activities of dipeptidase IV increased by 18.16% and 30.36%, indicating that the combined treatment of SAL and PAW can produce a synergistic effect and significantly improve the activity of dipeptidase.

[0063] Alanyl aminopeptidase is the most abundant aminopeptidase in meat processing, accounting for 80-83% of the total aminopeptidase activity in skeletal muscle sarcoplasm. Therefore, studying the activity of this enzyme is of great significance. Figure 3 As shown in Figure E, both the PAW and SAL treatments showed significant increases in alanyl aminopeptidase activity, effectively increasing free amino acid content and improving the flavor of air-dried goose. Mechanistically, SAL treatment may optimize the enzymatic reaction microenvironment by regulating muscle tissue water activity (Aw value), while PAW treatment, through the abundant reactive oxygen species (ROS) and reactive nitrogen species (RNS) in its curing liquid, effectively enhances myocyte membrane permeability and promotes the release of endogenous proteases. Combined SAL-PAW treatment exhibits a significant synergistic enhancement effect through the dual pathways of physical osmotic pressure regulation and the action of chemically active substances, providing a new theoretical basis for optimizing traditional meat processing.

[0064] 4. Effects of different treatments on the hydrolysis index of air-dried goose protein

[0065] 0.7 g of air-dried goose sample was weighed and added to 7 mL of cold distilled water, and homogenized at 12000 rpm for 30 seconds. 300 μl of extract was added to 1200 μl of 12.5% ​​trichloroacetic acid solution, vortexed at 4°C for 15 minutes, and centrifuged at 2000 g for 10 minutes. After adjusting the pH of the supernatant to 9.0, 180 μl of fluorescamine was added and incubated at 25°C in the dark for 1 hour. Finally, the fluorescence intensity was measured using a fluorescence spectrophotometer at λex = 375 nm and λex = 475 nm. A standard curve was drawn using different concentrations of glycine (50-50 mM glycine) to calculate the amino content in the air-dried goose extract. At the same time, before trichloroacetic acid treatment, the total protein concentration in the air-dried goose extract was determined using a BCA kit. The proteolysis index (PI%) is expressed as the percentage of the N-terminal α-amino content of the air-dried goose sample relative to the total protein content.

[0066] The protein hydrolysis index (PI) has an important influence on the tenderness and flavor of meat products during meat processing. Figure 4 As shown, compared with the control (CK) group, the proteolytic index in both the SAL and PAW groups showed significant increases (p < 0.05), reaching 32.78% and 33.42%, respectively. The SAL-PAW combined treatment group showed even greater results, with an increase of 62.6%. These results confirm that both Salicornia herbacea salt and plasma-activated water effectively activate the protein degradation system, and that their combined treatment produces a significant synergistic effect. Notably, this synergistic effect is highly consistent with data from previous experiments demonstrating increased protease activity, suggesting that enhanced enzyme activity directly drives a systemic improvement in proteolytic capacity. PAW treatment also alters the myofibril structure of air-dried goose, making it easier for Salicornia herbacea salt to penetrate and act within the meat product, effectively improving product quality. Mechanistically, PAW treatment disrupts the physical structure of air-dried goose meat products and increases the permeability of the myofibril matrix. These changes in myofibril structure facilitate the penetration of components in the Salicornia herbacea salt into the deeper layers of the muscle cells, further optimizing the microenvironment for endogenous proteases by modulating ion channel activity and cell membrane potential. The above synergistic mechanism ultimately makes the product effect of the SAL-PAW combined treatment group optimal.

[0067] 5. Effects of different treatments on the free amino acid content of air-dried goose

[0068] One gram of chopped air-dried goose meat was homogenized with 25 mL of trichloroacetic acid (5 g / 100 mL) and sonicated at room temperature for 20 minutes. After standing for 2 hours, the mixture was filtered through double-layer filter paper and centrifuged at 12,000 × g for 30 minutes at 4°C. 400 μL of the supernatant was then transferred to a vial for derivatization and analyzed using an amino acid analyzer. An Agilent Hypersil ODS column (5 μm, 4 × 250 mm) was used, with a mobile phase flow rate of 1 mL / min and a column temperature of 30°C. The mobile phase consisted of phosphate buffer (0.01 M, pH 2.3) at a flow rate of 0.8 mL / min. The detection wavelength was 210 nm. The free amino acid (FAA) content was then determined by high-performance liquid chromatography (HPLC), with pre-column derivatization performed. The results are shown in Table 2.

[0069] Table 2 Effects of different curing methods on the composition and content of free amino acids in the obtained air-dried goose

[0070]

[0071]

[0072] Note: In the table, ac: different letters indicate significant differences among different treatment groups (p<0.05).

[0073] Table 2 shows the free amino acid (FAA) content in air-dried goose under different treatments. The increase in free amino acids can compensate for the reduced saltiness caused by salt reduction and improve the nutritional value of the meat product, confirming previous data. The total FAA content in the SAL-PAW group was significantly higher than in the other groups, indicating that this treatment effectively promotes protein degradation and releases more free amino acids. The PAW and SAL groups also exhibited higher total FAA content, suggesting that both PAW and the samphire plant salt have a certain promoting effect. Glutamic acid (Glu) and aspartic acid (Asp), the primary umami amino acids, were significantly increased compared to the CK group. Serine (Ser), proline (Pro), glycine (Gly), threonine (Thr), and alanine (Ala), the sweet-tasting amino acids, were significantly increased in the treated groups compared to the control group. While bitter amino acids increased slightly with protein hydrolysis, the increase was minimal and did not negatively impact the product's flavor. After treatment with Salicornia herbacea salt and plasma-activated water (PAW), the SAL-PAW group showed the highest total free amino acid content. This is likely due to the organic substances in the Salicornia herbacea salt, such as minerals like calcium and magnesium, which effectively improve water activity (Aw), thereby promoting enzymatic hydrolysis, releasing more free amino acids, and further enhancing the taste of the meat product. The active substances in PAW can promote protein degradation, releasing more free amino acids, and enhancing the umami and sweetness of the meat. Furthermore, PAW may also accelerate protein hydrolysis by increasing cell membrane permeability and enhancing the leakage of endogenous proteases. This indicates that this combined treatment method effectively addresses the high salt content, dry and hard texture, and poor flavor of traditional air-dried goose.

[0074] 6. Effects of different treatments on pH, TBARS and color of air-dried goose

[0075] 2g of air-dried goose meat was added to 18mL of deionized water and homogenized twice at 8000r / min for 30s each time. The pH value of each goose meat sample was then measured using a pH meter, with each sample tested three times.

[0076] For the fat oxidation rate (TBARS) assay, 4 g of air-dried goose meat was accurately weighed and 36 mL of 10% (v / v) trichloroacetic acid (TCA) was added. The mixture was homogenized at 8000 rpm / min for 1 min, followed by centrifugation at 8000 rpm for 10 min. 2 mL of the supernatant was mixed with 2 mL of 0.02 mol / L thiobarbituric acid solution, heated at 90°C for 40 min, and then cooled to room temperature. The absorbance of 200 μL of the supernatant was measured at 532 nm. Color difference was measured using a CR-440 colorimeter and expressed as L* (lightness), a* (redness), and b* (yellowness) parameters in CIELabsystem. The goose meat was sliced ​​into uniform thin slices (4 cm × 4 cm × 2 cm) before each measurement. Each meat sample was measured six times in parallel.

[0077] pH is an important indicator for measuring the quality of meat products. Changes in pH can affect the interaction between proteins, thereby affecting protein structure and other functional properties. Figure 5 As shown in Figure A, the pH values ​​of the SAL-PAW, PAW, and SAL groups were all lower than those of the control group. The results indicate that the pH value of the PAW group decreased due to the presence of abundant nitrogen oxides in the PAW solution. These substances are highly acidic in water, which leads to a decrease in the pH value of the water. These substances not only degrade the protein in the meat products, but also generate hydrogen ions (H + ), causing the pH value to decrease. However, the pH value after the combined treatment (SAL-PAW) was lower than that of the group using PAW alone, indicating that the natural minerals (calcium and magnesium) in the sea salt may have buffered the acidity of PAW, thereby maintaining a moderate acidic environment, which is conducive to the degradation of protein and the release of umami amino acids. pH can reflect the freshness of meat, and meat contains a large number of microorganisms. Under the decomposition and metabolism of these microorganisms, they consume the protein and sugar substances in the meat to produce acidic substances, which lowers the pH. If the pH drops too much, it will have an adverse effect on the quality of meat products. NaCl has the effect of inhibiting the growth of spoilage microorganisms, and the use of SAL-PAW combined treatment for pickling in this study did not increase the degree of spoilage of meat products, indicating that it has achieved the effect of reducing salt and preventing spoilage.

[0078] like Figure 5Figure B shows the effect of curing with different curing solutions on the TBARS value of air-dried goose. The TBARS value of meat products reflects the degree of fat oxidation and is an important indicator of their quality. Excessively high TBARS values ​​can lead to unpleasant odors, such as rancidity. This study investigated the effects of different treatments on fat oxidation in air-dried goose by measuring the TBARS values ​​of different curing groups. Experimental data showed that curing with Salicornia plant salt slightly increased the TBARS value of air-dried goose compared to the control group (CK). This is likely due to the reduced NaCl content, which intensifies the growth of putrefactive microorganisms and increases fat oxidation, leading to adverse effects. However, the PAW group significantly reduced its TBARS value, likely due to its higher nitrite content. Nitrite, through its antioxidant effects and inhibition of microbial growth, reduces fat oxidation, thereby maintaining a lower TBARS value. The values ​​for the combined SAL-PAW treatment group demonstrate that this combined curing solution not only prevents fat spoilage but also reduces sodium chloride intake, improving product quality overall.

[0079] Color is the consumer's intuitive feeling about air-dried goose meat and affects the consumer's acceptance.

[0080] Table 3 Effects of different curing methods on the skin color of air-dried goose

[0081]

[0082] Note: In the table, ac: different letters indicate significant differences among different treatment groups (p<0.05).

[0083] As shown in Table 3, the PAW group had the highest skin brightness (L*), while the SAL and SAL-PAW groups had the lowest. This may be due to the brown color of the Salicornia herb salt itself, which reduced the skin brightness after curing. In the PAW group, the rich active substances in the curing liquid may have reduced the degree of oxidative deterioration in the dried goose, making the skin brighter. The higher redness values ​​(a*) in the SAL and SAL-PAW groups are also related to the reddish-brown color imparted by the Salicornia herb salt to the dried goose surface.

[0084] The red color of meat products is caused by nitrosohemoglobin produced by the reaction of myoglobin and NO.

[0085] Table 4 Effects of different curing methods on the color of air-dried goose internal muscle

[0086]

[0087] Note: In the table, ac: different letters indicate significant differences among different treatment groups (p<0.05).

[0088] Table 4 shows that the brightness (L*) of the cured air-dried goose meat was similar. The redness (a*) values ​​of the PAW and SAL-PAW groups were significantly higher than those of the CK group. This may be because the PAW-cured air-dried goose contains sufficient nitrite, which can induce the reaction between myoglobin and NO. The increased a* value in the SAL group may be due to the infiltration of salts from the Salicornia herb. The increased b* value may be related to the formation of myoglobin in the meat. The nitrite generated during plasma treatment can oxidize myoglobin to metmyoglobin, thereby promoting the increase in b* value.

[0089] The above description is not intended to limit the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by persons of ordinary skill in the art within the spirit and scope of the present invention shall also fall within the scope of protection of the present invention.

Claims

1. A pickling solution based on plasma-activated water and Salicornia herbacea plant salt, characterized by: The pickling liquid is obtained by dissolving sodium chloride and samphire salt in plasma-activated water. The pickling liquid is a plasma-activated water mixture containing 4-7.2 wt % of sodium chloride and 0.8-4 wt % of samphire salt.

2. The pickling liquid based on plasma-activated water and Salicornia herba plant salt according to claim 1, characterized in that: The pickling liquid is a plasma-activated water mixture containing 4.8 wt % of sodium chloride and 3.2 wt % of samphire plant salt.

3. The pickling liquid based on plasma activated water and Salicornia herba plant salt according to claim 1, characterized in that The preparation method of the plasma-activated water is as follows: pure water is treated by a plasma jet device using air as a carrier gas, with the gas flow rate set at 28-32 L / min, the power at 680-700 W, and the treatment time at 5-15 min to obtain the treated plasma-activated water.

4. Use of the pickling liquid according to any one of claims 1 to 3 in preparing low-salt air-dried goose.

5. The use according to claim 4, characterized in that The preparation method of the low-salt air-dried goose comprises the following steps: Step 1: Treat pure water with a plasma jet device using air as a carrier gas to obtain treated plasma-activated water; Step 2: Immerse the washed goose meat in the pickling solution according to any one of claims 1 to 3, pickle it at a ratio of 1000 to 2000 mL of pickling solution per kilogram of goose meat, and then air-dry it to obtain green low-salt air-dried goose.

6. The use according to claim 4, characterized in that Step 1 is specifically as follows: pure water is treated with a plasma jet device using air as a carrier gas, with the gas flow rate set to 28-32 L / min, the power to 680-700 W, and the treatment time to 5-15 min, to obtain treated plasma-activated water.

7. The use according to claim 4, characterized in that: The pickling liquid in step 2 is a plasma-activated water mixture containing 4.8 wt % of sodium chloride and 3.2 wt % of Salicornia herbacea plant salt.

8. The use according to claim 4, characterized in that: The curing temperature of the air-dried goose described in step 2 is 0-4° C., and the curing time is 24 hours.

9. The use according to claim 4, characterized in that: The air-drying temperature of the air-dried goose in step 2 is 14-18° C., the relative humidity is 65-70%, and the air-drying is performed for 2-4 days.

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