Method for prolonging storage period of sturgeon caviar

Abstract

The invention discloses a method for prolonging the storage period of sturgeon caviar, which comprises the following steps: adding a salicornia extract and sodium chloride into the sturgeon caviar, pickling with salt, canning, and storing in an environment of-4 DEG C, the weight ratio of the salicornia extract to the sodium chloride being (35-45): (55-65); the weight ratio of the sturgeon caviar to the salicornia bigelovii extract is 50: (0.9-1.2). The salicornia bigelovii extract is prepared by the following steps: mixing dry salicornia bigelovii powder with water, performing ultrasonic extraction or heating extraction for 1-2 times, centrifuging to obtain supernate, concentrating, and freeze-drying to obtain the salicornia bigelovii extract. According to the method for prolonging the storage period of the sturgeon caviar, phospholipid metabolism is improved by adjusting the proportion of water to salt, then the storage period of the sturgeon caviar is prolonged, and experiments show that the acid value is reduced, the generation of hydrogen peroxide is reduced, the generation of malondialdehyde is reduced, the catalytic oxidation of lipidosome is promoted, and the storage period of the sturgeon caviar is prolonged. The flavor quality and the shelf life of the sturgeon caviar are obviously enhanced.

Description

Technical Field

[0001] The invention relates to a method for prolonging the storage period of sturgeon caviar, belonging to the technical field of fresh-keeping of sturgeon caviar. Background Art

[0002] Sturgeon caviar, a premium food ingredient made from sturgeon roe, is a popular delicacy with its plump, salty flavor and lustrous dark color. However, caviar is prone to spoilage, making preservation a hot topic of research. Traditional preservation methods, such as the use of antioxidants and preservatives, can produce foreign odors, hindering sales. Thermal processing techniques, such as pasteurization, inevitably denature the caviar's proteins, causing a loss of elasticity and affecting its taste. Salting is currently the most common method for processing caviar, but a high-salt diet can pose health risks. Therefore, reducing salt content is an important development direction in the food processing industry. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention provides a method for prolonging the storage period of sturgeon caviar.

[0004] The present invention is achieved through the following technical solutions: A method for extending the storage period of sturgeon caviar comprises adding a samphire extract and sodium chloride to the sturgeon caviar, salting the mixture, canning the mixture, and storing the mixture at -4°C. The weight ratio of the samphire extract to the sodium chloride is (35-45):(55-65), and the weight ratio of the sturgeon caviar to the samphire extract is 50:(0.9-1.2), preferably 50:1.08.

[0005] The salicon carmichaelii extract is prepared by the following method: mixing salicon carmichaelii dry powder with water, performing ultrasonic extraction or heating extraction for 1-2 times, centrifuging to obtain a supernatant, concentrating, and freeze-drying.

[0006] Furthermore, the dry powder of Salicornia herba can be purchased on the market or prepared by oneself: the dry powder of Salicornia herba is obtained by collecting Salicornia herba, washing it, drying it and crushing it.

[0007] Furthermore, the samphire extract is prepared by the following method: taking 9 g of samphire dry powder, adding 100 mL of water, and extracting with 60 W ultrasonic wave for 60 min; centrifuging at 4000 rpm for 20 min, taking the supernatant, adding 50 mL of water to the precipitate, and extracting with 60 W ultrasonic wave for 30 min; centrifuging at 4000 rpm for 20 min, and taking the supernatant; combining the two supernatants, concentrating by rotary evaporation (60°C, 60 rpm), and freeze-drying to obtain the extract.

[0008] Furthermore, the samphire extract is prepared by the following method: taking 9 g of samphire dry powder, adding 100 mL of water, and extracting in a water bath at 60°C for 120 min; centrifuging at 4000 rpm for 20 min, taking the supernatant, adding 50 mL of water to the precipitate, and extracting in a water bath at 60°C for 30 min; centrifuging at 4000 rpm for 20 min, and taking the supernatant; combining the two supernatants, concentrating by rotary evaporation (60°C, 60 rpm), and freeze-drying to obtain the extract.

[0009] Preferably, the weight ratio of the Salicornia herba extract to sodium chloride is 40:60.

[0010] A sturgeon caviar preservative is composed of the above-mentioned samphire extract and sodium chloride, wherein the samphire extract accounts for 35% to 45% and the sodium chloride accounts for 55% to 65%, calculated by weight.

[0011] Preferably, the extract of Salicornia herba accounts for 40% and the sodium chloride accounts for 60%.

[0012] The sturgeon caviar preservative is used in the storage of sturgeon caviar. Specifically, the sturgeon caviar preservative is added to the sturgeon caviar, salted, canned, and stored at -4°C. The weight ratio of the sturgeon caviar to the samphire extract is 50:(0.9-1.2), preferably 50:1.08.

[0013] The present invention extracts the salicornia extract from the salicornia dry powder. The basic characteristics experiment shows that the ash content of the salicornia extract is about 60%, the main inorganic elements are Na, K, Mg, Ca and other inorganic elements, the mineral content is rich, and it is rich in free amino acids, and umami amino acids account for more than 30% of the total free amino acids. The total phenol (3.6% to 3.8%) and total sugar (5.3% to 5.5%) contents are high, and it has a strong antioxidant effect and strong antioxidant stability. There is no significant change after storage at room temperature and away from light for 30 weeks. It is rich in aldehydes, ketones and alcohols, which makes it have a fatty aroma, fruity aroma and malt aroma. In addition, the ultrasonic water extraction extract (SUW) of salicornia and the water bath water extraction extract (SWW) of salicornia are significantly different in nutritional composition. The ash content of SUW is lower than that of SWW, while the total free amino acids and total phenols content are significantly higher than those of SWW ( P The difference is smaller (<0.05). Salicornia herba extract is a mixture of crystals and organic matter. SUW has a smooth and complete crystal structure, uniform crystal size, and overall superior performance to SWW.

[0014] The present invention's method for extending the storage period of sturgeon caviar is based on improving phospholipid metabolism by adjusting the water-salt ratio, thereby extending the storage period of sturgeon caviar. Experiments have shown that with prolonged storage, the total colony count and TBARS of the sturgeon caviar first increase and then decrease, the pH first decreases and then increases, and the TVB-N increases. Compared with the control group, the samphire extract significantly reduced the total colony count, TVB-N, and TBARS of the sturgeon caviar ( P <0.05), which can effectively extend the storage period of sturgeon caviar for more than 2 weeks, and the effect of the 40% SUW treatment group in inhibiting the formation of TVB-N was significantly higher than that of the 40% SWW treatment group. In terms of texture, the elasticity and cohesion of sturgeon caviar showed a trend of first increasing and then decreasing, and the adhesion first decreased and then increased; compared with the control group, the sea lily extract improved the elasticity and cohesion of sturgeon caviar as a whole, and the 40% SWW treatment group had a more obvious effect on improving the elasticity and cohesion of sturgeon caviar, while the color difference fluctuation of sturgeon caviar in the 40% SUW treatment group was smaller. In terms of flavor quality, free amino acids showed an overall upward trend, fatty acids and volatile flavor substances showed an overall trend of first increasing and then decreasing, and odor substances increased rapidly in the later stage of storage; compared with the control group, the sea lily extract significantly reduced the degree of fatty acid oxidation in sturgeon caviar in the middle and late stages of storage (4 to 6 weeks) ( P <0.05), the DHA and EPA contents in the 40% SUW treatment group were significantly higher than those in the 40% SWW treatment group ( P <0.05), the content of off-flavor and flavor substances was significantly reduced ( P <0.05). Meanwhile, the content of some light flavor compounds, such as cream, rose, and floral, increased, indicating that the extract from Salicornia herba can reduce nutritional loss during storage of sturgeon caviar, inhibit lipid oxidation, prolong the optimal flavor release time, and enrich its flavor profile. The sensory quality of sturgeon caviar showed an overall downward trend; compared with the control group, the sensory evaluation results of the experimental group in the late storage period (5-6 weeks) were significantly improved ( P <0.05), indicating that samphire extract can slow the deterioration of the sensory quality of sturgeon caviar. Specifically, phospholipid peroxide levels peaked after six days of storage and decreased after eight days. This suggests that after six days of room temperature storage, phospholipid decomposition exceeded phospholipid formation, leading to significant off-flavor chemicals and a significant quality decline. Adjusting the water-salt ratio in this invention reduced the acid value by 27% to 30%, hydrogen peroxide production by 25%, and malondialdehyde production by 38%, thereby reducing the synthesis and oxidation of unsaturated fatty acids and inhibiting lipid hydrolysis.

[0015] The present invention also investigated potential metabolic pathways to explore the molecular processes underlying the interactions between essential amino acids, phospholipids, and unique flavor components in sturgeon caviar after adjusting the water-salt ratio. When the water-salt ratio of sturgeon caviar is adjusted, protein breakdown produces a large number of amino acids (such as glutamic acid, arginine, leucine, and lysine) and their derivatives, which interact with lipid oxidation products. Phospholipid breakdown and free fatty acid oxidation are the primary mechanisms of lipid oxidation in caviar. PC and PE are the primary phospholipids, containing oleic and linoleic acids, and are important precursors for the production of aroma chemicals. Adjusting the water-salt ratio promotes lipase-catalyzed oxidation, leading to the production of unique volatile compounds, significantly enhancing the flavor quality and shelf life of sturgeon caviar.

[0016] Various terms and phrases used herein have the general meanings that are well known to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : Sample images of SUW and SWW, where the left side is SUW and the right side is SWW.

[0018] Figure 2 : Equivalent salty concentration of SUW aqueous solutions with different concentrations, where the abscissa is the concentration of the Salicornia herba extract solution, in mg / mL.

[0019] Figure 3 : Flavor radar chart of NaCl aqueous solutions with different concentrations.

[0020] Figure 4 : Flavor radar charts of SUW aqueous solutions with different concentrations.

[0021] Figure 5 : Flavor radar chart of SUW aqueous solution and SWW aqueous solution.

[0022] Figure 6 : Determination results of inorganic elements in Salicornia herba extracts.

[0023] Figure 7 : Flavor radar chart of SUW aqueous solutions with different replacement ratios.

[0024] Figure 8 : Determination results of free amino acid content in Salicornia herba extract.

[0025] Figure 9 : Determination results of components of Salicornia herba extract.

[0026] Figure 10 : Volatile flavor fingerprint of Salicornia herba extract.

[0027] Figure 11: Microstructure observation results of Salicornia herba extract, where the left, middle and right are NaCl, SUW and SWW respectively.

[0028] Figure 12 : Determination results of antioxidant capacity changes of Salicornia herba extracts.

[0029] Figure 13 : Changes in bacterial colonies during storage of sturgeon caviar.

[0030] Figure 14 : pH changes of sturgeon caviar during storage.

[0031] Figure 15 : Changes of TVB-N content in sturgeon caviar during storage. Letters are used to indicate significant differences.

[0032] Figure 16 : Changes of TBARS content in sturgeon caviar during storage. Letters are used to indicate significant differences.

[0033] Figure 17 : Texture changes of sturgeon caviar during storage, where the left, middle, and right are elasticity, cohesion, and adhesion, respectively; letters are used to indicate significant differences.

[0034] Figure 18 : Color changes of sturgeon caviar during storage, including L*, a*, b*, and ∆E from left to right and from top to bottom.

[0035] Figure 19 : Heat map of changes in free amino acid content in sturgeon caviar during storage, where Na: control group; 4U: 40% SUW treatment group; 4W: 40% SWW treatment group.

[0036] Figure 20 : Changes in the content of different fatty acids in sturgeon caviar during storage, where the left, middle, and right are the control group, SUW group, and SWW group, respectively.

[0037] Figure 21 : Changes in fatty acid content of sturgeon caviar during storage.

[0038] Figure 22 : Fingerprint of flavor changes in sturgeon caviar during storage.

[0039] Figure 23 : Changes in volatile compounds of sturgeon caviar during storage.

[0040] Figure 24 : Differences in phospholipid content of sturgeon caviar during storage.

[0041] Figure 25 : VIP images of sturgeon caviar during storage (SUW group and control group).

[0042] Figure 26 : VIP images of sturgeon caviar during storage (SWW group and control group).

[0043] Figure 27 : Correlation analysis between flavor compounds and characteristic phospholipids in sturgeon caviar during storage. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the embodiments. However, the scope of the present invention is not limited to the following embodiments. Those skilled in the art will appreciate that various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention.

[0045] Unless otherwise specified, the instruments, reagents, and materials used in the following examples are all conventional instruments, reagents, and materials available in the prior art and can be obtained through regular commercial channels. The experimental methods and detection methods used in the following examples are all conventional experimental methods and detection methods available in the prior art, unless otherwise specified.

[0046] The dried powder of Salicornia herbacea used in the present invention was purchased from Lvyuan Salt Soil Agricultural Science and Technology Co., Ltd. in Yancheng, Jiangsu Province, and the Russian sturgeon caviar was purchased from Xunlong Science and Technology Co., Ltd. in Quzhou, Zhejiang Province.

[0047] Experiment 1 Study on the basic properties of Salicornia herba extract (1) In this experiment, ultrasonic water extraction and water bath water extraction were used to extract the extract of Salicornia herba.

[0048] Ultrasonic water extraction method: take 9 g of Samphire dry powder, add 100 mL of pure water, and extract at 60 W ultrasonically for 60 min; centrifuge at 4000 rpm for 20 min, take the supernatant, add 50 mL of pure water to the precipitate, and extract at 60 W ultrasonically for 30 min; centrifuge at 4000 rpm for 20 min, take the supernatant; combine the two supernatants, concentrate by rotary evaporation (60℃, 60 rpm), and freeze-dry to obtain the Samphire ultrasonic water extract, abbreviated as SUW, with an extraction yield of 32.99%±0.35%.

[0049] Water bath extraction method: take 9 g of Samphire dry powder, add 100 mL of pure water, and extract in a water bath at 60℃ for 120 min; centrifuge at 4000 rpm for 20 min, take the supernatant, add 50 mL of pure water to the precipitate, and extract in a water bath at 60℃ for 30 min; centrifuge at 4000 rpm for 20 min, take the supernatant; combine the two supernatants, concentrate by rotary evaporation (60℃, 60 rpm), and freeze-dry to obtain the Samphire water bath extract, abbreviated as SWW, with an extraction yield of 31.61%±0.22%.

[0050] Sample pictures of SUW and SWW are as follows Figure 1 As shown, SUW is light green in color and SWW is light yellow-green in color.

[0051] (2) Determination of equivalent saltiness concentration based on water-salt ratio Sensory Saltiness Measurement: Twenty panelists aged 20 to 35 years (9 female and 11 male) were selected. All panelists were untrained but had experience in sensory evaluation. Before participating in the sensory evaluation, panelists were provided with coded NaCl solutions at concentrations of 30 mmol / L, 40 mmol / L, 50 mmol / L, 60 mmol / L, and 70 mmol / L and asked to rank the solutions from saltiest to least salty. Panelists who correctly ranked the solutions were further tested. Ultimately, 11 panelists were selected for the sensory evaluation: 6 female and 5 male, aged 20 to 33 years. Panelists had no issues with taste or smell and had abstained from food or beverages for at least one hour before the sensory evaluation began.

[0052] Sample Preparation: Prepare 500 mL of SUW aqueous solutions at concentrations of 3 mg / mL, 5 mg / mL, 7 mg / mL, and 9 mg / mL, respectively. Use chlorophyll to adjust the color until no significant difference is visible to the naked eye. Reference Solution Preparation: Prepare 300 mL of NaCl aqueous solutions at concentrations of 30 mmol / L, 40 mmol / L, 50 mmol / L, 60 mmol / L, 70 mmol / L, 80 mmol / L, and 90 mmol / L, respectively. The reference solutions are scored 30, 40, 50, 60, 70, 80, and 90 points, respectively, and the samples are scored on a 100-point scale. Sensory Preparation: Prepare 50 mL sample cups and add 20 mL of the above prepared solutions to each cup. Prepare the samples. Label the four sample solutions with a three-digit random number and present them in random order along with all the reference solutions to the panelists. The panelists will score the samples based on the scores assigned to the reference solutions. The results are averaged.

[0053] Electronic Tongue Saltiness Measurement: The reference solution and sample solution (sample solution without chlorophyll coloring) used in this sensory evaluation were subjected to electronic tongue testing. 35 mL of the test solution was dispensed into a dedicated electronic tongue testing cup, and taste data was collected at room temperature according to the standard testing procedure. Electronic tongue parameters: The sample measurement was set to continuously record the potential value for 30 seconds; followed by two rapid rinses, each lasting 3 seconds; and then the potential value of the reference solution was measured to obtain aftertaste data. After completing these steps, the entire testing process was repeated four times, the data from the first cycle was discarded, and the average of the subsequent three cycles was used as the final result.

[0054] Figure 2 The sensory salinity results of SUW aqueous solutions with different concentrations are shown. The salinity is positively correlated with the concentration. As the concentration increases, the salinity of the sea salicornia extract increases. The salinity of the four concentrations of SUW aqueous solutions used in the experiment ranges from 36 to 92 mmol / L NaCl. The error bar of 7 mg / mL is the smallest, which is the most stable point for the sensory evaluation. The subsequent comparison test of the salinity difference between SUW and SWW will be carried out at this concentration. Using SUW concentration and equivalent salinity as the calibration curve, the sensory equivalent salinity equation of SUW is obtained as: Y=9.477X+5.886, R 2 =0.9906 (Y: equivalent salty concentration, mmol / L NaCl; X: SUW concentration, mg / mL).

[0055] Combined with electronic tongue to evaluate the saltiness effect of Salicornia herba extract, the reference solution for sensory evaluation was first tested by electronic tongue, and the results were as follows: Figure 3 The flavor radar chart of NaCl aqueous solutions with different concentrations shows that the electronic tongue saltiness value is positively correlated with the NaCl concentration. As the concentration increases, the saltiness increases. Using the NaCl concentration and electronic tongue saltiness as a standard curve, the relationship equation between NaCl concentration and electronic tongue saltiness is obtained: Y=0.112X-3.082, R 2 =0.9969 (Y: electronic tongue saltiness value; X: NaCl concentration, mmol / L), which served as the basis for the subsequent calculation of the relationship between the electronic tongue saltiness of the Salicornia herba extract and the NaCl concentration.

[0056] The sensory evaluation experimental group and 50 mmol / L NaCl solution were subjected to electronic tongue measurement and obtained Figure 4 The following is a flavor radar chart of SUW aqueous solutions of different concentrations. As SUW concentration increases, saltiness also increases. The electronic tongue saltiness of 3 mg / mL SUW (8.23±0.04) is higher than that of 50 mmol / L NaCl (2.65±0.00). Substituting the electronic tongue saltiness of the experimental group into the equation for the relationship between NaCl concentration and electronic tongue saltiness (Y=0.112X-3.082, R 2 =0.9969) The electronic tongue saltiness value can be converted into NaCl concentration, and the equivalent saltiness equation of SUW electronic tongue is further obtained: Y=11.285X+67.508, R2 =0.9909 (Y: equivalent saltiness concentration, mmol / L NaCl; X: SUW concentration, mg / mL).

[0057] (3) Comparative analysis of salinity between SUW and SWW Sensory evaluation: 20 tasters (including 12 females and 8 males) were selected for paired comparison tests. Sample preparation: 500 mL of SUW aqueous solution and SWW aqueous solution with a concentration of 7 mg / mL were prepared respectively. Sensory preparation: During the sensory evaluation, the tasters will randomly obtain 2 samples. The sample combinations may be AB, BA, AA, BB. Each sample combination has an equal chance of being evaluated. Use three random codes to name each sample. During the sensory evaluation, the tasters are required to evaluate in order from left to right and fill in the questionnaire to answer "same" or "different". The statistical results are shown in Table 1. The χ is calculated according to the formula 2 , if χ 2 >χ0 2 (3.84), it proves that there is a significant difference between the two ( P <0.05).

[0058] .

[0059]

[0060] Electronic tongue verification: The two samples for sensory evaluation were subjected to electronic tongue measurement using the same method.

[0061] SUW and SWW are extracts of Salicornia herba extracted by different methods. There may be certain differences in the salinity of the two. The difference was compared using the concentration with the smallest error bar in the sensory equivalent salinity experiment (7 mg / mL). A combination of electronic tongue and artificial sensory methods was used to determine whether there was a significant difference in the salinity of SUW and SWW. Figure 5 This is the flavor radar chart of SUW aqueous solution and SWW aqueous solution measured by electronic tongue. It can be seen that the difference in saltiness between SUW and SWW is not obvious. After analyzing the data, the saltiness between the two is significantly different ( P <0.05), but the difference is extremely small (0.2), and the electronic tongue system believes that the difference is less than 0.5, which means that there is no difference between the two in actual sensory perception.

[0062] The results of the paired comparison test of the difference between 0.7 mg / mL SUW aqueous solution and 0.7 mg / mL SWW aqueous solution are shown in Table 2.

[0063]

[0064] χ 2 =0.27<3.84, indicating that there is no significant difference in the saltiness between SUW and SWW ( P <0.05). Based on the electronic tongue and sensory results, it can be judged that there is no difference in saltiness between SUW and SWW.

[0065] The above results indicate that the conclusions of sensory saltiness and electronic tongue saltiness of SUW are also applicable to SWW, and the saltiness results of SUW can represent the two Salicornia herba extracts extracted in this study.

[0066] (4) Analysis of inorganic element content Sample pretreatment: 0.2 g of SUW and SWW, respectively, were placed in a digestion tube. 5 mL of concentrated nitric acid and 0.5 mL of 30% H₂O₂ solution were added. The mixture was thoroughly mixed and allowed to stand at room temperature for 2 h (until the solution became clear and no sample powder was observed). The samples were then digested in a digestion oven. Digestion conditions were: 160°C for 15 min, 170°C for 15 min, and 180°C until 1 mL of liquid remained. The liquid was transferred to a 25 mL volumetric flask. The digestion tube was rinsed with 10 mL of ultrapure water twice. The combined solutions were then brought to a total volume of 25 mL with ultrapure water. A certain volume of the diluted solution was diluted to the appropriate ratio, and 5 mL was passed through a 0.22 μm aqueous filter membrane. The filtered solution was then analyzed by inductively coupled plasma mass spectrometry.

[0067] Inductively coupled plasma mass spectrometry (ICP-MS) detection conditions: After the instrument was ignited and stabilized for approximately 30 minutes, high-purity argon was used as the carrier gas. Experimental conditions were: plasma RF power maintained at 1550 W, and the plasma gas flow rate controlled at 15.0 L / min. The spray chamber temperature was maintained at 2°C, and the sampling depth was set at 8.0 mm. The experiment was repeated three times, and the results were averaged.

[0068] Figure 6 The inorganic element composition of samphire extract is shown in Figure 2. The main inorganic elements in samphire extract are Na, K, and Mg, with the Na content being approximately 47.85% of that of table salt. Ca also contributes a certain saltiness, but at a lower level. Combined with the equivalent salinity equation for samphire extract, the sodium-reducing effect of samphire extract was calculated. The results show that the sodium-reducing effect of samphire extract is above 60%. As the replacement salinity increases, the sodium-reducing effect of samphire extract decreases. At the same salinity as 4% NaCl, the sodium-reducing effect of samphire extract is approximately 63.47%.

[0069] (5) Optimal replacement ratio of Salicornia herba extract The sensory ranking experiment was conducted in accordance with GB / T 12315-2008.

[0070] Sensory Evaluation: Personnel Selection: As described above, 12 sensory tasters (7 female and 5 male) were ultimately selected. Sample Preparation: The experiment stipulated that all samples had a theoretical salinity of 50 mmol / L NaCl. 50 mmol / L NaCl served as the blank group, while 30% KCl and 10% MgCl2 served as the control group. SUW with salinity substitutions of 30%, 40%, 50%, 60%, and 70% served as the experimental group. Each group was prepared with 500 mL of aqueous solution. 50 mL sample cups were prepared, and 20 mL of the prepared solution was added to each cup, ready for use. The eight sample solutions were labeled with a three-digit random code and presented in random order to the tasters. The tasters then ranked all samples based on saltiness and summed the results.

[0071] Electronic tongue test: The 8 sample solutions used in this sensory evaluation were subjected to electronic tongue test using the same method.

[0072] Figure 7 This is a flavor radar chart of SUW aqueous solutions at different replacement ratios, as measured by an electronic tongue. The saltiness results show no difference in saltiness between 50 mmol / L NaCl, 30% KCl, and 10% MgCl2. The saltiness values ​​are similar, but increasing with increasing SUW replacement ratios increases. The saltiness of 40% SUW replacement is closest to that of the blank control, representing the optimal replacement ratio as measured by the electronic tongue. Based on the sensory and electronic tongue results, a 40% replacement with samphire extract is the optimal replacement ratio, and this ratio will be used in future sturgeon caviar storage experiments.

[0073] (6) Determination of free amino acids Weigh 2.0 g of each SUW and SWW into an ampoule, add 15 mL of 0.02 mol / L hydrochloric acid, and sonicate for 5 min. Centrifuge at 5000 rpm for 10 minutes at 4°C, and collect the supernatant. Repeat the above procedure for precipitation. Combine the supernatants from both centrifugations and dilute to 50 mL with ultrapure water. Pipette 2 mL of this dilute solution, add an equal volume of 5% sulfosalicylic acid solution, and centrifuge (10000 rpm, 4°C, 10 min). Pass the supernatant through a 0.22 μm aqueous filter and transfer to a liquid phase vial for later use. Analyze using an automated amino acid analyzer. Perform three replicates, and average the results.

[0074] The results of free amino acid content determination of the salicornia extract are shown in Figure 8. The amino acids with higher content are glutamic acid, aspartic acid, proline, serine, and arginine. The umami free amino acid content in the salicornia extract accounts for more than 30% of the total free amino acids, indicating that free amino acids are an important factor in the salty taste of the salicornia extract. The free amino acid content of SUW is significantly higher than that of SWW ( P<0.05), indicating that it is more nutritious. In addition, samphire extract also contains other important amino acids such as taurine (Tau) and gamma-aminobutyric acid (GABA).

[0075] (7) Determination of composition The moisture content of the Salicornia herba extract was determined using the direct drying method specified in GB 5009.3-2016. The ash content of the samples was quantitatively analyzed according to the high-temperature ignition method specified in GB 5009.4-2016. The protein content of the samples was determined and calculated using a protein content detection kit (Coomassie Brilliant Blue method). The total sugar content was determined using the phenol-sulfuric acid method. The total flavonoids content was determined according to SN / T 4592-2016. The total phenol content was determined using the Folin-phenol method.

[0076] The results of the determination of the components of the extract of Salicornia herba are as follows Figure 9 As shown in the figure, it can be concluded that the main components of the extract of Salicornia herba are inorganic salts, with ash accounting for about 60%; it is rich in total sugar and total flavonoids, with the total sugar content being about 6% and the total flavonoid content being about 3.8%. The content of protein, total phenols and total flavonoids in SUW is significantly higher than that in SWW ( P <0.05), the nutrient content of SUW was higher.

[0077] (8) Gas phase-ion mobility spectrometry (GC-IMS) 1.0 g of SUW and SWW samples were weighed into headspace vials, 1 mL of ultrapure water was added, and the mixture was thoroughly mixed. The mixed samples were then incubated in a thermostatic shaker at 60°C, 500 rpm, for 20 minutes. High-purity nitrogen (≥99.999%) was used as the carrier gas, with the inlet temperature set at 85°C. A 500 μL injection was performed in splitless mode. A RESTEK MXT-5 capillary column (15 m × 0.53 mm × 1 μm) was used, the column temperature set at 60°C, and the analysis time was set to 25 minutes. The carrier gas flow rate gradient program was as follows: 2.0 mL / min for 2 minutes, then a constant increase to 10 mL / min over 10 minutes, a constant increase to 100 mL / min over 20 minutes, and finally a constant increase to 150 mL / min over 25 minutes. The ion mobility spectrometer operated at 45°C.

[0078] The volatile flavor compounds of the extract of Salicornia herba were analyzed by GC-IMS. Figure 10 As shown. A total of 39 flavor components were analyzed, including 20 aldehydes, 5 ketones, 2 alcohols and 12 other compounds. Aldehydes have a low flavor threshold and contribute more to flavor. The aldehydes with higher content in the extract of Salicornia are ( E )-2-pentenal ("strawberry, fruit, tomato"), (E )-2-heptenal ("fat"), 3-methylbutanal ("malt"), make the whole extract of samphire present fat, fruit and malt aroma. Compared with SWW, SUW has more aldehydes. E,E The contents of volatile flavor compounds such as )-2,4-heptadienal ("fat") and heptanal ("green, fat") are significantly higher than those in SWW, making the fatty aroma of SUW stronger.

[0079] (9) Scanning electron microscopy analysis SUW, SWW, and NaCl were ground into fine powder and passed through a 200-mesh sieve for later use. A layer of conductive adhesive was applied under the sample holder, and the powder was evenly sprinkled onto the adhesive. Loose surface particles were removed using an air sweeping method. A 10 nm gold film was then deposited using a magnetron sputtering device to enhance conductivity. Micromorphology was characterized using a high-resolution scanning electron microscope at an accelerating voltage of 10 kV, with a working distance set at 10 mm and images acquired using a secondary electron detector.

[0080] The microstructure of the extract of Salicornia herba was observed by scanning electron microscopy. Figure 11 As shown. Salicornia extract is a mixture of organic matter and crystalline particles, with the crystalline particles embedded in the organic matter. Comparison of the microstructures of Salicornia extracts extracted by ultrasonic extraction and waterbath extraction revealed that the crystal structure of SUW is sharp, with smooth, complete cubes and tetrahedrons, a more pronounced crystal structure, and a relatively uniform size distribution. In contrast, SWW exhibits irregular crystal morphology, uneven size, and some crystal aggregation.

[0081] (10) Antioxidant assay DPPH free radical scavenging assay: Samples were prepared into aqueous solutions of varying concentrations (0.125, 0.25, 0.5, 1, 2, and 4 mg / mL). A 0.1 mg / mL DPPH working solution was prepared in ethanol. Equal volumes of the sample solution and DPPH working solution were thoroughly mixed and allowed to react in the dark at room temperature for 30 minutes. The absorbance at 515 nm was measured using a microplate reader. The positive control was VC. Sample blank group A0 consisted of an equal volume of anhydrous ethanol substituted for DPPH. Control group A1 consisted of an equal volume of anhydrous ethanol substituted for the sample solution. Control blank group A2 consisted of anhydrous ethanol.

[0082] DPPH free radical scavenging rate (%) = .

[0083] The samples were prepared into aqueous solutions at different concentrations (6.25, 12.5, 25, 50, 100, and 200 mg / mL). 100 μL of the sample solution was transferred to an EP tube. Equal volumes of FeSO₄ solution (9 M) and salicylic acid-ethanol solution (9 M) were added, respectively, and vortexed to mix thoroughly. 100 μL of H₂O₂ solution (9 M) was added and vortexed again to mix thoroughly. The mixed solution was incubated at 37°C for 30 minutes, and the absorbance at 510 nm was measured using a microplate reader. VC was used as a positive control. For the blank group A0, an equal volume of ultrapure water was used instead of the sample. For the control group A1, an equal volume of pure ultrapure water was used instead of the H₂O₂ solution.

[0084] Hydroxyl radical scavenging rate (%) = .

[0085] The samples were prepared into aqueous solutions of different concentrations (0.125, 0.25, 0.5, 1, 2, and 4 mg / mL). ABTS working solution: 10 mL of 0.33 mg / mL K2S2O8 aqueous solution was prepared, 0.01925 g of ABTS was added, mixed, and reacted at room temperature in the dark for 12 h. Dilute to A before use. 734 nm The absorbance was 0.700 ± 0.020. The sample solution was mixed with ABTS working solution at a ratio of 1:4 (v:v). The reaction was allowed to proceed for 10 minutes at room temperature in the dark. The absorbance at 734 nm was measured using a microplate reader. VC was used as a positive control. Sample blank group A0 consisted of an equal volume of ultrapure water replacing ABTS. Control group A1 consisted of an equal volume of ultrapure water replacing the sample solution. Control blank group A2 consisted of ultrapure water.

[0086] ABTS clearance (%) = .

[0087] The extracts of Salicornia herba (SUW and SWW) were stored at room temperature and away from light (30 weeks), and the changes in their antioxidant capacity were determined according to the above method. The results are as follows: Figure 12 The DPPH scavenging rate, hydroxyl radical scavenging rate, and ABTS scavenging rate at the maximum value of SUW and SWW did not change significantly, indicating that storage at room temperature and in the dark for 30 weeks had little effect on the antioxidant capacity of the Salicornia herba extract and that the Salicornia herba extract had good storage stability.

[0088] Experiment 2 Effects of Salicornia herba extract on the storage quality of sturgeon caviar The effect of samphire extract on the storage quality of sturgeon caviar was studied by treating it with samphire extract. The experiment was designed with 3 groups: 40% SUW treatment group (SUW group), 40% SWW treatment group (SWW group), and control group. The SUW group was operated as follows: 2.7 g of preservative (composed of 40% SUW and 60% sodium chloride, i.e. 1.08 g SUW and 1.62 g sodium chloride) was added to 50 g of sturgeon caviar, mixed with salt, marinated, canned, and stored at -4°C for 6 weeks, with regular sampling and testing.

[0089] The SWW group was operated as follows: 2.7 g of a preservative (composed of 40% SWW and 60% sodium chloride, i.e., 1.08 g SWW and 1.62 g sodium chloride) was added to 50 g of sturgeon caviar, mixed with salt, and canned. The caviar was then stored at -4°C for 6 weeks, with regular sampling and testing.

[0090] The control group was treated by adding 2.7 g of sodium chloride to 50 g of sturgeon caviar, salting it, storing it at -4°C for 6 weeks, and taking samples regularly for testing.

[0091] The sampling test items and results are detailed below.

[0092] (1) Effect of Salicornia herba extract on the freshness of sturgeon caviar during storage In the 0th week (i.e. before storage), 2nd week, 3rd week, 4th week, 5th week and 6th week of storage, samples were taken to detect the total colony count, pH, TVB-N content and TBARS content.

[0093] Total colony count determination: The total colony count of sturgeon caviar was determined using the plate count method. Accurately weigh 5.0 g of caviar and add 45 mL of sterile saline solution to homogenize for 120 seconds. Continuously dilute the homogenized sample solution with sterile saline to the appropriate multiple and select the appropriate ratio for inoculation. Inoculate 1 mL of the sample solution into 15 mL of PCA medium, vortex to mix, and allow to solidify. The solidified plate was then inverted and incubated in a 27°C incubator for 48 hours. The colony units formed on the plate were counted. Three replicates were made for each dilution, and the results were averaged.

[0094] pH determination: Homogenize 5.0 g of caviar with 45 mL of ultrapure water in a food homogenizer for 120 seconds. Let stand for 30 minutes, then filter and measure the pH of the supernatant. Repeat three times and average the results.

[0095] Determination of volatile basic nitrogen: The TVB-N content of sturgeon caviar was determined in accordance with the third method of the national standard GB 5009.228-2016.

[0096] Malondialdehyde determination: The malondialdehyde content of sturgeon caviar was determined according to the second method of national standard GB 5009.181-2016.

[0097] The changes of bacterial colonies during storage of sturgeon caviar are as follows: Figure 13 As shown. With the extension of storage time, the total colony count of sturgeon caviar showed a trend of first increasing and then decreasing. The total colony count of the control group reached a maximum of 6.13 lg (CFU / g) at the 4th week, exceeding the national standard for fresh meat [<6 lg (CFU / g)]. After 4 weeks, the total colony count steadily decreased and remained at a high level [>5.5 lg (CFU / g)]. The decrease in the total colony count may be related to the death of thermophilic bacteria during long-term refrigeration in the late storage period, and the psychrophilic bacteria became the dominant spoilage bacteria. The total colony count of the experimental group from 2 to 6 weeks was significantly lower than that of the control group ( P <0.05), reaching the maximum [<5.5 lg(CFU / g)] on the 3rd week, and then rapidly decreasing after 3 weeks. Before 3 weeks, the total colony count in the 40% SWW treatment group was significantly lower than that in the 40% SUW treatment group. After 4 weeks, the total colony count in the 40% SUW treatment group was significantly lower than that in the 40% SWW treatment group, indicating that SWW had a better inhibitory effect on the dominant microorganisms in the early stage of storage, while SUW had a better inhibitory effect on the dominant microorganisms in the late stage of storage.

[0098] The pH changes of sturgeon caviar during storage are as follows: Figure 14 As shown in the figure, during storage, the pH of caviar first decreased and then increased with increasing storage period. The pH of the control group decreased from 6.17 to 5.97, then began to rise rapidly from the fourth week, ultimately reaching 6.17. The pH of the 40% SUW-treated group decreased from 6.07 to 6.02, then began to rise from the fifth week, reaching 6.11 by the sixth week. The pH of the 40% SWW-treated group decreased from 6.08 to 6.03, then began to rise from the fifth week, reaching 6.12 by the sixth week. The pH increase in the experimental groups (0.09) during the later stages of storage was significantly lower than that in the control group (0.2).

[0099] The changes of TVB-N content in sturgeon caviar during storage are as follows Figure 15 As shown in Figure 2, the TVB-N content of sturgeon caviar increased with the extension of storage time. From the second week onwards, the TVB-N content of the experimental group was significantly lower than that of the control group ( P <0.05), on the 6th week, the TVB-N content in the 40% SUW treatment group was significantly lower than that in the 40% SWW treatment group ( P <0.05).

[0100] The changes of TBARS content in sturgeon caviar during storage are as follows: Figure 16As shown in the figure, the TBARS value of sturgeon caviar increases with storage time and stabilizes after the fourth week. Hydroperoxide is unstable and easily decomposes, leading to an increase in malondialdehyde content. Moderate lipid oxidation can bring a characteristic flavor to sturgeon caviar, while excessive oxidation will bring a rancid and fishy odor, resulting in a decrease in the flavor quality of the caviar. Throughout the storage period, the TBARS value of the experimental group was significantly lower than that of the control group ( P <0.05), the difference was even greater in the later storage period (4-6 weeks), and there was no significant difference between 40% SUW and 40% SWW ( P >0.05), the extract of Salicornia herba can slow down the lipid oxidation rate of sturgeon caviar during storage, reduce the generation of small molecules such as aldehydes and ketones, and significantly reduce the degree of lipid oxidation in the later stage of storage, which is beneficial to the maintenance of flavor quality in the later stage of storage.

[0101] (2) Effect of Salicornia herbacea extract on the textural properties of sturgeon caviar during storage The elasticity, cohesion, and adhesion of sturgeon caviar were measured using a texture analyzer. The procedure was as follows: eight randomly selected caviar samples were placed in a circular shape. The displacement rate was set to 60 mm / min, the dynamic load threshold was limited to 50 N, the initial trigger force was 0.15 N, the secondary compression was set to 20% deformation, and the time interval was 2 seconds. The procedure was repeated three times for each sample group, and the results were averaged.

[0102] The color parameters L*, a*, and b* of the samples were measured using a 3nh colorimeter. The measurements were repeated three times, and the average of the results was taken to calculate the ∆E value.

[0103] .

[0104] The texture changes of sturgeon caviar during storage Figure 17 As shown. During the entire storage period, the overall elasticity showed a trend of first increasing and then decreasing, and the elasticity reached its highest point at 2 weeks. The elasticity of the experimental group was better than that of the control group. The 40% SWW treatment group performed better in terms of elasticity. At the 2nd week, the elasticity of the 40% SWW treatment group reached 0.47 mm, while that of the control group was 0.43 mm. The gap between the two gradually widened with time, reaching 0.33 mm and 0.26 mm respectively at the 6th week. As the storage period prolonged, the cohesion of the experimental and control groups showed an overall fluctuating downward trend. At the 3rd to 4th week, the cohesion of the experimental group was significantly higher than that of the control group ( P <0.05), and tended to be the same from the 5th to the 6th week. On the 3rd week, the 40% SWW treatment group was significantly higher than the 40% SUW treatment group ( P<0.05). Adhesion plays a very important role in the quality evaluation of sturgeon caviar. Appropriate adhesion can better showcase the flavor and delicate texture of sturgeon caviar. The adhesion of sturgeon caviar containing salsa chinensis extract fluctuated during storage. From 0 to 2 weeks, there was no significant difference in adhesion between the experimental group and the control group ( P >0.05), at 3-4 weeks, the adhesion of the control group was significantly higher than that of the experimental group ( P <0.05), the adhesion of the experimental group on the 6th week was significantly higher than that of the control group ( P <0.05).

[0105] The color changes of sturgeon caviar during storage are as follows: Figure 18 As shown. The L*, a*, and b* values ​​of sturgeon caviar showed an overall fluctuating downward trend during storage. At 0 w, the L* and b* of the experimental group were lower than those of the control group, and the difference was more obvious. Among them, the low L* may be related to other substances such as sugars in the samphire extract. These substances will absorb moisture on the surface of the caviar, thereby reducing the brightness at 0 w; the low b* may be related to the color of the samphire extract itself. As the storage time prolonged, the L*, a*, and b* between the experimental group and the control group showed a fluctuating downward trend, and the color of the sturgeon caviar gradually deteriorated. The degree of color change in the experimental group was lower than that in the control group, and the growth rate of ∆E slowed down significantly. In the late storage period (5-6 w), the ∆E of the experimental group was significantly lower than that of the control group ( P <0.05). This suggests that the extract from Salicornia herba may slow the color deterioration of caviar during storage by inhibiting microbial activity and protein degradation, thereby better preserving its sensory quality. Compared to the 40% SWW treatment, the 40% SUW treatment exhibited less color fluctuation, suggesting that SUW is superior in maintaining the color stability of sturgeon caviar products.

[0106] (3) Effect of Salicornia herba extract on the flavor characteristics of sturgeon caviar during storage 0.5 g of sturgeon caviar sample was mixed with 20 mL of chloroform-methanol (v:v, 2:1) solution, extracted statically in a 4°C refrigerator for 2 h, and then filtered. The filtrate was mixed with 10 mL of normal saline and centrifuged (4000 rpm, 4°C, 10 min). The lower layer was dried under nitrogen purge to obtain total lipids. The total lipid sample was dissolved in 3 mL of 0.125 mol / L KOH-methanol solution, vortexed, and heated in a 60°C water bath for 30 min. The saponified sample solution was cooled to room temperature, and an equal volume of boron trifluoride-methanol solution was added. The water bath heating cycle was repeated. Once the solution cooled to room temperature, 1 mL of ultrapure water and 2 mL of n-hexane were added, mixed, and the layers separated. The supernatant was collected and the supernatants were combined. The resulting solution was nitrogen purge to constant weight, transferred to a 10 mL volumetric flask, made up to volume with n-hexane, and filtered through a 0.22 μm organic filter membrane for GC-MS analysis of fatty acid content.

[0107] GC conditions: An HP-5ms column (30 m × 0.25 mm × 0.25 mm) was used, with high-purity helium as the carrier gas at a flow rate of 1.5 mL / min. The temperature program was set as follows: 60°C for 1 min, followed by a gradient increase at 10°C / min, 3°C / min, and 6°C / min to 160°C, 200°C, and 280°C, each held for 5 min, 10 min, and 5 min, respectively. The injection volume was 1 μL.

[0108] MS conditions were set as follows: electron energy, ion source temperature, solvent excision time, and mass scan range were set to 70 eV, 250°C, 2 min, and 35–500 m / z, respectively. Quantitative analysis was achieved using the NIST08 spectral library search results and a standard curve obtained under the same conditions.

[0109] The heat map of changes in free amino acid content of sturgeon caviar during storage is shown in Figure 2. Figure 19 As shown in Figure 2, the amount of free amino acids showed an overall upward trend with the extension of storage time. In the early storage period, the content of free amino acids in the 40% SUW treatment group was significantly higher than that in the control group, while the content in the 40% SWW treatment group was significantly lower than that in the control group ( PGlutamic acid was the most abundant amino acid in the free amino acids of sturgeon caviar. On week 4, the glutamate contents in the control, 40% SUW, and 40% SWW groups were 117.26±2.59, 114.78±0.68, and 111.83±0.19 mg / 100 g, respectively. Although the glutamate content in the control group was slightly higher than that in the experimental group, the difference was not significant. On week 5, the glutamate contents in the control, 40% SUW, and 40% SWW groups reached 134.14±0.33, 123.79±0.51, and 120.92±1.06 mg / 100 g, respectively. The free amino acid content in the control group increased rapidly. The free amino acid content in the control group increased at a faster rate than that in the experimental group, and its free amino acid content was generally higher than that in the experimental group during the middle and late stages of storage (weeks 4-6).

[0110] Changes in the content of different fatty acids in sturgeon caviar during storage Figure 20 The results show that fatty acid content changes dynamically throughout storage, influenced and regulated by multiple factors, including microbial activity, lipid hydrolysis, and fatty acid oxidation. With extended storage, fatty acids undergo oxidative degradation, producing volatile compounds such as aldehydes and ketones, leading to a decrease in the fatty acid content of sturgeon caviar. The total amount of fatty acids in the control group decreased significantly by the sixth week, indicating that fatty acid production in the control group was lower than fatty acid decomposition, indicating more severe lipid deterioration.

[0111] Changes in fatty acid content of sturgeon caviar during storage Figure 21A total of 17 free fatty acids were detected. Palmitic acid (C16:0) and oleic acid (C18:1n-9t) were the highest content saturated and monounsaturated fatty acids, respectively. Linoleic acid (C18:2n-6t), DHA (C22:6n-3), and EPA (C20:5) were the highest content polyunsaturated fatty acids. DHA and EPA have been shown to have positive effects on brain development and are present in high concentrations in caviar fatty acids. The DHA and EPA contents of the experimental group were generally higher than those of the control group. At the 6th week, the fatty acid content of the control group decreased rapidly, and the difference in DHA and EPA between the experimental and control groups reached its maximum. At this time, the EPA contents of the control group, 40% SUW treatment group, and 40% SWW treatment group were 3.36±0.35 mg / 100 g, 4.54±0.37 mg / 100 g, and 4.37±0.31 mg / 100 g, respectively; the DHA contents of the control group, 40% SUW treatment group, and 40% SWW treatment group were 14.32±0.66 mg / 100 g, 20.08±0.84 mg / 100 g, and 18.61±0.27 mg / 100 g, respectively. The results showed that the 40% SUW treatment group had higher DHA and EPA contents and a lower degree of oxidation of unsaturated fatty acids.

[0112] GC-IMS: 1.0 g of lyophilized sturgeon caviar powder was accurately weighed and placed in a headspace vial. 1 mL of physiological saline was added and mixed thoroughly. The mixed sample was incubated in a thermostatic shaker for 20 min (60°C, 500 rpm). High-purity nitrogen (≥99.999%) was used as the carrier gas. The inlet temperature was set at 85°C. A 500 μL sample was injected in splitless mode. A RESTEK MXT-5 capillary column (15 m × 0.53 mm × 1 μm) was used. The column temperature was set at 60°C, and the analysis time was set to 25 min. The carrier gas flow rate gradient program was: 2.0 mL / min for 2 min, followed by a constant increase of 1 mL / min, 9 mL / min, 10 mL / min, and finally 10 mL / min, 100 mL / min, and 150 mL / min. The ion mobility spectrometer operated at 45°C.

[0113] Gas chromatography-mass spectrometry (GC-MS): 1.0 g of lyophilized sturgeon caviar powder was accurately weighed and placed in a headspace vial. 3 mL of saturated saline was added and mixed thoroughly. 2-methyl-3-heptanone solution was used as the internal standard. The mixture was incubated at 60°C for 30 min. GC conditions: An HP-5MS column (60 m × 0.25 mm × 0.25 μm) was used, and high-purity nitrogen (≥99.999%) was used as the carrier gas. The gradient temperature program was as follows: 50°C for 3 min, then 3°C / min to 100°C for 2 min, then 6°C / min to 180°C for 2 min, and finally 10°C / min to 250°C for 3 min. MS conditions: electron energy, ion source temperature, and mass scan range were set to 70 eV, 230°C, and 35–500 m / z, respectively. The relative contents of flavor compounds were calculated using the following formula using the NIST08 spectral library search results.

[0114] Relative content of compound = internal standard concentration ( )× .

[0115] After GC-IMS analysis, the Figure 22 The fingerprint is shown in Figure 2. GC-IMS results show that there are 21 volatile flavor compounds in sturgeon caviar, including 5 ketones, 5 aldehydes, 5 alcohols, and 6 other compounds. A large number of volatile flavor compounds are produced or increased in content at 2 weeks, for example ( E )-2-heptenal, ( E )-2-pentenal, 2-hexenal, 1-penten-3-one, 2-hexenol, 2-methyl-1-butanol, etc., reached the maximum at the 4th week and then decreased. The content of 2-pentanone, acetone, ethyl acetate, diethylmethylamine, n-butanol, etc. continued to increase with the extension of storage period. At 4 weeks, ( E )-2-heptenal ("fatty, almond-like"), ( EThe caviar's flavor reached its peak at 2-pentenal ("fruity, strawberry"), 2-hexenal ("green, apple"), 1-penten-3-one ("fishy, ​​pungent"), 2-hexenol ("green, wine-like, fruity"), and 2-methyl-1-butanol ("malty"), indicating its richest flavor. The content of these volatile compounds decreased significantly after 4 weeks, with the rate of decline in the experimental group being slower than that in the control group, extending the optimal flavor release period. Between 5 and 6 weeks, the content of 2-pentanone ("fruity, ethereal"), acetone ("ethereal"), n-butanol ("medicinal, fruity"), ethyl acetate ("pineapple"), and diethylmethylamine ("roasted, barbecued") further increased. A slight off-flavor developed in the late stages of storage, with the off-flavor compounds in the experimental group significantly lower than in the control group. The samphire extract inhibited the deterioration of the caviar's flavor. The overall content of flavor substances in the experimental group showed a trend of being lower than that in the control group. However, the content of 2,3-butanedione ("creamy"), 2-ethyl-1-hexanol ("rose scent, green"), and ethyl propionate ("floral scent") in the experimental group was significantly higher than that in the control group, bringing a fresh flavor to the sturgeon caviar and enriching the flavor profile of the sturgeon caviar.

[0116] Changes in volatile compounds during storage of sturgeon caviar Figure 23 As shown. A total of 21 volatile flavor substances were detected, including 3 aldehydes, 13 alcohols, 3 ketones, and 2 acids. Aldehydes contribute more to flavor due to their lower threshold, among which hexanal, ( E )-2-hexenal, ( Z )-4-heptenal provides flavors such as "fat, green, and cream". Among the flavor substances in the control group, 1-penten-3-ol ("buttery, pungent"), ( E The levels of 1-2-penten-1-ol ("mushroom flavor") and 1-octen-3-ol ("mushroom flavor") reached their highest levels on the 5th week. These substances can produce unpleasant flavors such as "pungent" and "mushroom-like," indicating that the caviar flavor deteriorated significantly by the 5th week. The experimental group had lower levels of these volatile compounds than the control group at the 5th week. The levels of 1-butanol ("medicinal, fruity") and acetic acid ("sour") reached their highest levels on the 6th week, indicating further flavor deterioration. These levels were lower in the experimental group than in the control group. The addition of Salicornia extract slowed the flavor degradation of sturgeon caviar.

[0117] LC / MS was performed using a ZORBOX Eclipse Plus C18 column (Waters, Milford, USA, 100 mm × 2.1 mm × 1.8 μm). 1 g of phospholipids was mixed with 15 mL of chloroform / methanol (v / v = 2:1) and then 5 mL of ultrapure water was added. The mixture was incubated at 4°C for 1 hour and centrifuged at 5000 rpm for 10 minutes. The bottom layer was retained and repeatedly extracted with 10 mL of organic solvent. The weight was then uniformly weighed under nitrogen. A 20 μL mixture of each sample was prepared as a quality control sample for similar analysis.

[0118] The differences in phospholipid content of sturgeon caviar during storage are as follows: Figure 24 As shown in Figure 3, there were significant differences in PC and PE levels among the different groups. The changes in the concentrations of the top 30 metabolites under 40% SUW and NaCl and 40% SWW and NaCl conditions were monitored, as shown in Figure 3. Figure 25 、 Figure 26 The results showed that the fat content of the samples treated with Salicornia herba extract was significantly higher than that of the control group. VIP analysis identified several key differential lipids, including PE (15:2 / 18:3), PC (16:0 / 20:5), PC (14:1 / 20:4), PE (26:8 / 18:2CHO), PC (22:5 / 22:6), PC (22:1), PE (18:0 / 21:5CHO), PC (18:1), and PE (26:8 / 18:1 COOH), all with VIP > 2.

[0119] Phospholipids, the lipid class, showed the greatest variation. The fatty acid composition and acylation positions in phospholipids contribute to the formation of various flavor compounds. Correlation analysis elucidated the molecular mechanism of the interaction between phospholipids and specific flavor compounds, focusing on key differential lipids and six characteristic flavor compounds. Figure 2 As shown, Figure 27 Significant positive correlations were observed between major flavor compounds (including hexanal, (E)-2-hexenal, (Z)-4-heptenal, and 3-methyl-1-butanol) and PC and PE (containing oleic acid (18:1), α-linolenic acid (18:3), arachidonic acid (20:4), eicosapentaenoic acid (EPA, 20:5), and docosahexaenoic acid (DHA, 22:6)). PC and PE lipids and their degradation products, such as fatty acids and aldehydes, can serve as precursors for the biosynthesis or thermal degradation of specific flavor compounds. Notably, phospholipids containing C18:1, C20:5, and C22:6 chains are catalyzed by phospholipases to produce fatty acids, which are subsequently oxidatively degraded into flavor compounds. Elevated concentrations of PC and PE phospholipids may provide additional precursors for the synthesis of these specific aromatic compounds.

[0120] Example 1 Method for Prolonging the Storage Period of Sturgeon Caviar SUW group: 3.0 g of a preservative (composed of Salicornia herba extract SUW and sodium chloride, with SUW accounting for 40% and sodium chloride accounting for 60%, i.e., SUW: 1.20 g, sodium chloride: 1.80 g) was added to 50 g of sturgeon caviar (the weight ratio of sturgeon caviar to SUW was 50:1.2), mixed with salt, and canned and stored at -4°C for 6 weeks.

[0121] The operation of the SWW group is the same as the above method.

[0122] Example 2 Method for Prolonging the Storage Period of Sturgeon Caviar SUW group: 2.3 g of a preservative (composed of Salicornia herba extract SUW and sodium chloride, with SUW accounting for 40% and sodium chloride accounting for 60%, i.e., SUW: 0.92 g, sodium chloride: 1.38 g) was added to 50 g of sturgeon caviar (the weight ratio of sturgeon caviar to SUW was 50:0.92), and the fish were salted, canned, and stored at -4°C for 6 weeks.

[0123] The operation of the SWW group is the same as the above method.

[0124] The above examples are provided to those skilled in the art to fully disclose and describe how to implement and use the claimed embodiments, rather than to limit the scope of the disclosure herein. Modifications that are obvious to those skilled in the art will fall within the scope of the appended claims.

Claims

1. A method for extending the storage period of sturgeon caviar, characterized in that: Adding samphire extract and sodium chloride to sturgeon caviar, salting, canning, and storing in an environment at -4°C; wherein the weight ratio of samphire extract to sodium chloride is (35-45):(55-65), and the weight ratio of sturgeon caviar to samphire extract is 50:(0.9-1.2); The salicon carmichaelii extract is prepared by the following method: mixing salicon carmichaelii dry powder with water, performing ultrasonic extraction or heating extraction for 1-2 times, centrifuging to obtain a supernatant, concentrating, and freeze-drying.

2. A method for prolonging the storage period of sturgeon caviar according to claim 1, characterized in that: The extract of Salicornia herba is prepared by the following method: taking 9 g of dry powder of Salicornia herba, adding 100 mL of water, and extracting with ultrasound at 60 W for 60 min; centrifuging, taking the supernatant, adding 50 mL of water to the precipitate, and extracting with ultrasound at 60 W for 30 min; centrifuging, taking the supernatant; combining the two supernatants, concentrating by rotary evaporation, and freeze-drying to obtain the extract.

3. The method for prolonging the storage period of sturgeon caviar according to claim 1, characterized in that: The extract of Salicornia herba is prepared by the following method: taking 9 g of dry powder of Salicornia herba, adding 100 mL of water, extracting in a water bath at 60°C for 120 min; centrifuging, taking the supernatant, adding 50 mL of water to the precipitate, extracting in a water bath at 60°C for 30 min; centrifuging, taking the supernatant; combining the two supernatants, concentrating by rotary evaporation, and freeze-drying to obtain the extract.

4. The method for prolonging the storage period of sturgeon caviar according to claim 1, wherein: The weight ratio of the Salicornia herba extract to sodium chloride is 40:

60.

5. The method for prolonging the storage period of sturgeon caviar according to claim 1, characterized in that: The weight ratio of the sturgeon caviar to the samphire extract is 50:1.

08.

6. A sturgeon caviar preservative, characterized by: The invention is composed of a samphire extract and sodium chloride, wherein the samphire extract accounts for 35% to 45% and the sodium chloride accounts for 55% to 65%, calculated by weight percentage; The salicon carmichaelii extract is prepared by the following method: mixing salicon carmichaelii dry powder with water, performing ultrasonic extraction or heating extraction for 1-2 times, centrifuging to obtain a supernatant, concentrating, and freeze-drying.

7. The sturgeon caviar preservative according to claim 6, characterized in that: The extract of Salicornia herba is prepared by the following method: taking 9 g of dry powder of Salicornia herba, adding 100 mL of water, and extracting with ultrasound at 60 W for 60 min; centrifuging, taking the supernatant, adding 50 mL of water to the precipitate, and extracting with ultrasound at 60 W for 30 min; centrifuging, taking the supernatant; combining the two supernatants, concentrating by rotary evaporation, and freeze-drying to obtain the extract.

8. The sturgeon caviar preservative according to claim 6, characterized in that: The extract of Salicornia herba is prepared by the following method: taking 9 g of dry powder of Salicornia herba, adding 100 mL of water, extracting in a water bath at 60°C for 120 min; centrifuging, taking the supernatant, adding 50 mL of water to the precipitate, extracting in a water bath at 60°C for 30 min; centrifuging, taking the supernatant; combining the two supernatants, concentrating by rotary evaporation, and freeze-drying to obtain the extract.

9. The sturgeon caviar preservative according to claim 6, characterized in that: The samphire extract accounts for 40%, and sodium chloride accounts for 60%.

10. Use of the sturgeon caviar preservative according to any one of claims 6 to 9 in the storage of sturgeon caviar.

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