Deodorization method of wood frog meat

Abstract

The invention discloses a deodorization method of wood frog meat, and belongs to the technical field of agriculture. The method comprises the following steps: pretreatment of raw materials: taking leg muscles of wood frogs, cutting the leg muscles into meat blocks, and soaking the meat blocks in water for preservation for later use; preparation of a composite deodorization liquid: cleaning and draining coriander and mint leaves, respectively cutting the coriander and the mint leaves into fragments, crushing the fragments, mixing the crushed coriander and the crushed mint leaves in proportion to obtain a mixture, adding the mixture into water for soaking, and filtering after soaking to obtain the composite deodorization liquid; and performing fishy smell removal treatment: soaking the pretreated wood frog meat blocks into the prepared composite fishy smell removal liquid, and performing soaking and fishy smell removal. The deodorization liquid prepared from natural plant raw materials is used for deodorization treatment of the wood frog meat, is safe, environment-friendly and low in cost, and can improve the flavor and taste of the wood frog meat, remove the fishy smell so as to accord with the dietary preference of the public and improve the edible acceptability; the nutrition can be reserved, and high-quality raw materials are provided for developing diversified products such as leisure snacks, prefabricated dishes and quick-frozen foods.

Description

Technical Field

[0001] This invention relates to the field of agricultural technology, and in particular to a method for removing the fishy smell from frog meat. Background Technology

[0002] The forest frog (scientific name: *Ranatemporaria*) is an amphibian belonging to the family Ranidae and genus *Rana*. In China, it is mainly distributed in Northeast China, with broad-leaved forests and mixed coniferous and broad-leaved forests in areas such as the Changbai Mountains and the Lesser Khingan Mountains being preferred habitats. It is also found in parts of North and Northwest China, including parts of Inner Mongolia Autonomous Region, Hebei Province, Shanxi Province, Tianjin Municipality, and Beijing Municipality, where the climate and ecological environment are suitable for its survival and reproduction. As an animal with high economic value, the forest frog's oil has medicinal and nutritional value, and its meat is a highly promising food resource.

[0003] Forest frog meat is rich in various nutrients and is an excellent source of protein. Its protein content is high, and its amino acid composition is well-balanced, containing many essential amino acids to meet the body's normal physiological needs. At the same time, forest frog meat is relatively low in fat and contains unsaturated fatty acids, which help maintain cardiovascular health. Furthermore, the vitamins and minerals it contains further enhance its nutritional value.

[0004] However, because forest frogs typically inhabit damp forests and streamside areas, with a wide range of food sources including various insects and small invertebrates, their long-term exposure to this specific environment and dietary habits results in their meat releasing a strong fishy odor during cooking. This odor severely impacts the sensory quality of forest frog meat, reduces consumer acceptance, and significantly limits its promotion and application in the food processing and consumer markets. From a food processing perspective, the fishy odor makes it difficult to develop diversified products from forest frog meat, hindering the development of related food industries; from a consumer perspective, the strong fishy odor reduces people's willingness to buy forest frog meat, limiting its market share expansion.

[0005] Therefore, it is necessary to deodorize frog meat. However, existing deodorization processes for frog meat have significant shortcomings: some physical deodorization methods (such as blanching and adsorption) easily lead to nutrient loss and incomplete deodorization; chemical deodorization methods (such as using chemical reagents) may leave harmful substances, posing safety hazards; biological deodorization methods (such as enzymatic hydrolysis) are relatively safe, but they are costly, have difficult-to-control reaction conditions, and easily affect the texture of the meat. Based on this, there is an urgent need to develop a simple, low-cost, safe, and environmentally friendly deodorization process for frog meat. Summary of the Invention

[0006] In view of this, the main objective of the present invention is to provide a deodorization process for frog meat to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for removing the fishy smell from frog meat, comprising the following steps: S1. Raw material pretreatment: Take the leg muscles of the forest frog, cut them into chunks, soak them in water to keep them fresh, and set aside. S2. Preparation of compound deodorizing liquid: Wash and drain the coriander and mint leaves, cut them into pieces and crush them, mix the crushed coriander and mint leaves to obtain a mixture, add water to soak, filter after soaking to obtain compound deodorizing liquid; S3. Deodorization treatment: Immerse the pre-treated frog meat pieces in the compound deodorization solution prepared in step S2 and soak to remove the fishy smell. In step S2, the mass ratio of coriander to mint leaves is 1:2~4, and the ratio of the mixture to water is 1~5g:100ml; In step S3, the ratio of frog meat chunks to compound deodorizing solution is 1g:3~8ml, and the soaking time for deodorizing is 20~60min.

[0008] This invention utilizes food deodorizing spices to treat food, which not only aligns with people's dietary and cooking habits but is also simple to operate, low in cost, safe, and environmentally friendly. Cilantro and mint are common plants with unique aromas in daily life. Cilantro contains various volatile aromatic components, such as linalool and carvacrol, which give it its unique fragrance; mint is rich in volatile substances such as menthol and menthone, possessing a cool and refreshing aroma. In food processing, these spices can be used to mask or remove off-odors and improve the flavor of food.

[0009] This invention utilizes a compound deodorizing solution made from coriander and mint to treat frog meat, removing its fishy odor while imparting a unique flavor, providing a new approach and method for deodorizing frog meat. Single-factor experiments were conducted to investigate the effects of deodorizing solution concentration, deodorizing time, and the material-to-liquid ratio on the deodorization effect, initially determining the approximate range of each factor. Based on this, orthogonal experiments were used for optimization, with sensory evaluation as the main indicator, comprehensively considering the gloss, odor, and texture of the frog meat to determine the optimal deodorization process conditions. Simultaneously, to comprehensively and objectively evaluate the deodorization effect, thiobarbituric acid value (TBARS) determination and gas chromatography-ion mobility spectrometry (GC-IMS) were employed to assess the deodorization effect, providing a scientific basis and technical support for the rational development and utilization of frog meat, and contributing to its widespread application in the food industry.

[0010] Furthermore, in step S2, the mass ratio of coriander to mint leaves is 1:3, and the ratio of the mixture to water is 3g:100ml.

[0011] Furthermore, in step S3, the soaking time for deodorizing is 50 minutes.

[0012] Furthermore, in step S3, the ratio of frog meat chunks to the compound deodorizing solution is 1g:5ml.

[0013] Furthermore, in step S1, the size of the meat pieces is 0.5cm×0.5cm~1.5cm×1.5cm, and the water temperature is 0~8℃; In step S2, the fragment length is 0.5~1.5cm.

[0014] Further, in step S2, the mass ratio of coriander and mint leaves is 1:3, and the ratio of the mixture to water is 3g:100ml; In step S3, the ratio of frog meat chunks to compound deodorizing solution is 1g:5ml, and the soaking time for deodorizing is 50min.

[0015] In a second aspect, the present invention provides frog meat prepared by any of the above methods.

[0016] In a third aspect, the present invention provides the application of the above-described frog meat in the preparation of frog jerky, frog jerky, quick-frozen frog meatballs, ready-to-eat frog meat snacks, and quick-frozen frog meat prepared products.

[0017] The method for removing the fishy smell from frog meat provided by this invention has several advantages. First, it improves the flavor and texture of frog meat, removing the fishy smell to suit public dietary preferences and increase its acceptability. Second, it preserves the frog's nutrients, providing high-quality raw materials for developing diverse products such as snacks, pre-prepared dishes, and frozen foods. Third, it helps expand the frog meat consumer market, promotes the upgrading of the frog processing industry, and simultaneously promotes the development of the upstream aquaculture industry, achieving both economic and food resource utilization value.

[0018] The beneficial effects of this invention include at least the following: (1) Significant deodorizing effect: The present invention uses a natural deodorizing liquid made from coriander and mint. Its volatile components, such as linalool, carvacrol, and menthol, can effectively remove fishy substances such as hexanal, pentanal, and propanal from frog meat through masking and neutralization.

[0019] (2) Complete nutrient retention: This process does not require high-temperature treatment, but only removes the fishy smell by soaking at room temperature, thus avoiding the loss of nutrients caused by physical deodorization methods. According to TBARS, the malondialdehyde content in the frog meat after deodorization decreased from 36.25 mg / kg to 31.63 mg / kg, and the degree of lipid oxidation was reduced.

[0020] (3) Safe, environmentally friendly and low cost: The deodorizing raw materials are natural edible plants with no risk of chemical reagent residues, which meet the food safety requirements; coriander and mint are widely available and inexpensive, and the deodorizing liquid preparation and deodorizing process are simple to operate without complicated equipment, making them suitable for large-scale production and application.

[0021] (4) Unique flavor optimization: The natural aroma components in the deodorizing liquid can give the frog meat a fresh herbal and fruity flavor, enrich the flavor layers of the product, enhance consumer acceptance, and lay the foundation for the development of diversified products such as snacks, pre-cooked dishes, and frozen foods from frog meat.

[0022] (5) Promote industrial development: This process solves the core technical bottleneck of industrialized processing of frog meat, which can promote the large-scale development of frog farming industry, enhance the economic value of frog products, and achieve a win-win situation for food resource utilization and economic benefits. Attached Figure Description

[0023] Figure 1 The effect of deodorizing solution concentration on the sensory evaluation of frog meat.

[0024] Figure 2 The effect of deodorization time on the sensory evaluation of frog meat.

[0025] Figure 3 The effect of feed-to-liquid ratio on the sensory evaluation of frog meat.

[0026] Figure 4 This is the standard curve for malondialdehyde.

[0027] Figure 5 This is a two-dimensional GC-IMS spectrum of volatile components in the sample. Explanation: The entire graph has a blue background. The red vertical line at 1.0 on the horizontal axis represents the RIP peak (reacting ion peak, normalized). The vertical axis represents the gas chromatographic retention time (s), and the horizontal axis represents the relative migration time (normalized, au). Each point on either side of the RIP peak represents a volatile organic compound. The color represents the peak intensity, ranging from blue to red; the darker the color, the greater the peak intensity.

[0028] Figure 6 This is a GC-IMS differential spectrum of volatile components in the sample.

[0029] Figure 7 This is a fingerprint spectrum of volatile components in the sample. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0032] The following specific embodiments illustrate the solution proposed in this invention: Example 1 1. Experimental materials: Forest frog samples were collected from Jiaohe City, Jilin Province. 2. Reagents and Instruments: 20% trichloroacetic acid (TCA) solution: Fujian Weizhenyuan Pharmaceutical Technology Co., Ltd.; thiobarbituric acid (TBA) solution: Shanghai Aladdin Biochemical Technology Co., Ltd.; n-ketones, 2-butanone, 2-pentanone, 2-hexanone, 2-heptanone, 2-octanone and 2-nonanone (all analytical grade): Shanghai Aladdin Biochemical Technology Co., Ltd.; 99.999% nitrogen, 20 mL headspace vial: Shandong Haineng Scientific Instruments Co., Ltd.; MXT-WAX capillary column (30 m × 0.53 mm, 1.0 μm): Restek Inc., USA.

[0033] The experimental equipment used is shown in Table 1.

[0034] Table 1. List of Instruments and Equipment

[0035] 3. Optimization of the process for removing the fishy smell from frog meat: 3.1 Raw material pretreatment: Take the meat from the frog's legs and cut it into 1 cm x 1 cm pieces. To ensure the freshness of the frog meat, soak the cut pieces in ice water before proceeding to the next step of deodorizing.

[0036] 3.2 Preparation of deodorizing solution: First, wash fresh cilantro and mint leaves thoroughly and drain. Then, chop each leaf into approximately 1 cm pieces and grind them using a food processor with a 60-mesh sieve. Next, mix the mint leaves and cilantro in a 1:3 mass ratio and soak them in distilled water at room temperature for 60 minutes. Using 100 mL of distilled water as a standard, the added solids should range from 1 to 6 g (i.e., 1, 2, 3, 4, or 5 g / 100 mL). After soaking, filter the solution through a sieve. The resulting filtrate will be a cilantro-mint compound deodorizing solution of varying concentrations.

[0037] 3.3 Single-factor experimental design: Effect of deodorizing solution concentration on the deodorization effect of frog meat: Five samples after treatment were randomly selected and soaked for 30 min with deodorizing solutions of concentrations of 1 g / 100 mL, 2 g / 100 mL, 3 g / 100 mL, 4 g / 100 mL and 5 g / 100 mL respectively, at a material-to-solution ratio of 1:3, to determine the optimal deodorizing solution concentration.

[0038] Effect of deodorization time on the deodorization effect of frog meat: Five samples after processing were randomly selected and deodorized for 20 min, 30 min, 40 min, 50 min and 60 min respectively at 25±2℃ under the conditions of deodorization solution concentration of 3 g / 100mL and material-to-liquid ratio of 1:3, so as to determine the optimal deodorization time.

[0039] Effect of material-liquid ratio on deodorization of frog meat: Five samples after treatment were randomly selected and tested at material-liquid ratios of 1:2, 1:3, 1:4, 1:5, and 1:6 under the conditions of a deodorization solution concentration of 3 g / 100 mL and a deodorization time of 30 min, respectively, to determine the optimal material-liquid ratio.

[0040] 3.4 Orthogonal Experiment Optimization Based on the results of the single-factor deodorization experiment, a three-factor, three-level orthogonal experiment was conducted, selecting the deodorization solution concentration, deodorization time, and material-to-liquid ratio. The optimal combination of deodorization conditions was selected using Table 2.

[0041] Table 2 Orthogonal Level Table

[0042] 3.5 Sensory Evaluation Methods Sensory evaluation was conducted on the frog meat after deodorization, using a 100-point scale for each component. The evaluation was based on Table 3, with each component assigned a maximum score. The scores from all components were then combined to form a final 100-point result.

[0043] Table 3 Sensory Rating Criteria

[0044] 4. Optimal selection of deodorization process for frog meat 4.1 Results of Single-Factor Experiments Single-factor experiments were conducted to investigate the effects of deodorizing solution concentration, deodorizing time, and feed-to-liquid ratio on the sensory evaluation of frog meat. The specific results are as follows: (1) Effect of deodorizing solution concentration on sensory evaluation of frog meat: Under the conditions of a fixed deodorization time of 30 min and a material-to-liquid ratio of 1:3, experiments were conducted with different deodorizing solution concentrations. The results are as follows: Figure 1 As shown.

[0045] When the concentration of the deodorizing solution increased from 1 g / 100 mL to 3 g / 100 mL, the total sensory score showed an upward trend, reaching a peak at 3 g / 100 mL; further increasing to 4-5 g / 100 mL, the total score decreased. Therefore, the optimal deodorizing solution concentration for frog meat is 3 g / 100 mL.

[0046] (2) Effect of deodorization time on sensory evaluation of frog meat: Under the conditions of a fixed deodorization solution concentration of 3 g / 100 mL and a material-to-liquid ratio of 1:3, different deodorization times were set for the experiment, and the results are as follows: Figure 2 As shown.

[0047] The total sensory score initially increased and then decreased over time, reaching its highest value at 50 minutes and then significantly decreasing at 60 minutes. Therefore, the optimal time for removing the fishy smell from frog meat is 50 minutes.

[0048] (3) Effect of feed-to-liquid ratio on sensory evaluation of frog meat: Under the conditions of a fixed deodorizing solution concentration of 3 g / 100 mL and a deodorizing time of 30 min, different feed-to-liquid ratios were tested, and the results are as follows: Figure 3 As shown.

[0049] The total sensory score initially increased and then decreased with increasing feed-to-liquid ratio, reaching a peak at a ratio of 1:5, and then significantly decreased at 1:6. Therefore, the optimal feed-to-liquid ratio of 1:5 yields the best deodorizing effect for frog meat.

[0050] In conclusion, the optimal overall quality of frog meat is achieved when the deodorizing solution concentration is 3 g / 100 mL, the time is 50 min, and the material-to-liquid ratio is 1:5.

[0051] 4.2 Optimization Results of Orthogonal Experiments This experiment employed a three-factor, three-level orthogonal design and an optimal process combination. The factors were the deodorizing solution concentration (A), deodorizing time (B), and material-to-liquid ratio (C), with specific levels set as follows: A1 (2 g / 100mL), A2 (3 g / 100mL), A3 (4 g / 100mL); B1 (40 min), B2 (50 min), B3 (60 min); C1 (1:4), C2 (1:5), C3 (1:6). The orthogonal experiment results are shown in the table below: Table 4 Results of the Three-Factor, Three-Level Orthogonal Experiment

[0052] Table 4 shows that the order of primary and secondary factors affecting the deodorization of frog meat is: C>A>B, i.e., material-to-liquid ratio>deodorizing solution concentration>deodorization time. Therefore, the material-to-liquid ratio has the greatest impact on the deodorization of frog meat, leading to the optimal deodorization conditions being A2B2C2. This combination did not appear in the orthogonal experiment. To verify the reliability of the above results, a three-group verification experiment was conducted together with the highest sensory score combination A2B2C3 from the orthogonal experiment. The experimental data are as follows: Table 5 Results of the optimal deodorization combination experiment

[0053] As shown in Table 5, the overall sensory score of combination A2B2C2 is higher than that of combination A2B2C3. Therefore, the optimal deodorization conditions for frog meat are A2B2C2, namely, a deodorization solution concentration of 3 g / 100 mL, a deodorization time of 50 min, and a material-to-liquid ratio of 1:5.

[0054] 5. Evaluation of the effectiveness of the deodorization process for frog meat 5.1 Determination of thiobarbituric acid value of frog meat before and after deodorization treatment 5.1.1 Measurement Method The TBARS value was determined according to GB5009.181-2016 "National Food Safety Standard - Determination of Malondialdehyde in Food" with slight modifications. 5 g of frog meat (before and after deodorization) was weighed and placed in a 50 mL centrifuge tube. 12.5 mL of 20% trichloroacetic acid (TCA) solution was added. The mixture was homogenized at 10000 r / min for 20 s, then centrifuged at 5500 r / min for 15 min. The supernatant was collected after filtration. 2.50 mL of the filtrate was transferred to a 25 mL colorimetric tube, and 2.5 mL of 0.02 mol / L TBA solution was added. The mixture was boiled in a water bath for 10 min, then cooled to room temperature, and the absorbance was measured at 532 nm. Each sample was tested three times, and the average value was taken. 12.5 mL of 20% TCA solution was added to a 50 mL centrifuge tube (without frog meat), and the absorbance was measured simultaneously following the above procedure. A standard curve was plotted using malondialdehyde (MDA) as the standard substance. The TBARS value was represented by the MDA content in frog meat and calculated according to the following formula: X = (C × V) / m In the formula: X — Malondialdehyde content in the sample (mg / kg); c — the concentration of malondialdehyde in the sample solution obtained from the standard series curve (μg / mL). V—The final volume of the sample solution (mL); m — the mass (g) of the final sample solution.

[0055] Table 6 Dilution gradient of MDA stock solution

[0056] 5.1.2 Plotting the Standard Curve The standard curve results for malondialdehyde (MDA) are as follows: Figure 4 ,Depend on Figure 4 We know that the regression equation is y = 0.0747x + 0.0109, R0 2 =0.9994.

[0057] 5.1.3 Analysis of Thiobarbituric Acid Value (TBARS) Results The average absorbance of frog meat before deodorization was 0.1392, and the average absorbance after deodorization was 0.1254. According to the regression equation and formula, the malondialdehyde (MDA) content of frog meat before and after deodorization was 36.25 mg / kg and 31.63 mg / kg, respectively. Therefore, the decrease in MDA content indicates a decrease in the total lipid oxidation product (TBA) value and a reduction in the content of lipid oxidation products. This suggests that the deodorization process reduced the degree of lipid oxidation in frog meat to some extent.

[0058] 5.2 Analysis of the differences in volatile components of frog meat before and after deodorization treatment Gas chromatography-ion mobility spectrometry (GC-IMS) was used to analyze the volatile substances in frog meat that had not undergone deodorization and frog meat obtained after deodorization using the optimized process. Trace volatile organic compounds were detected by measuring trace volatile components in solid samples.

[0059] 5.2.1 Sample Preparation Take fresh, untreated frog meat and place it in a headspace bottle, seal it, and name it LW28-0001 (frog meat without deodorization). Process the deodorized frog meat obtained according to the optimal process, weigh out the same amount of frog meat and place it in a headspace bottle, seal it, and name it LW28-0002 (frog meat after deodorization).

[0060] 5.2.2 Sample Preparation Weigh 2 g of sample and place it in a 20 mL headspace vial. Incubate at 60 °C for 20 min before injecting the sample.

[0061] 5.2.3 Headspace injection conditions Incubation temperature: 60℃; Incubation time: 20 min; Injection volume: 500 µL; Splitless injection; Incubation speed: 500 r / min; Injection needle temperature: 85℃.

[0062] 5.2.4 GC Conditions Column temperature: 60℃; Carrier gas: High-purity nitrogen (purity ≥99.999%); Programmed pressure ramp: Initial flow rate 2.0 mL / min, held for 2 min, linearly increased to 10.0 mL / min within 8 min, linearly increased to 100.0 mL / min within 10 min, held for 20 min. Chromatographic run time: 40 min; Injector temperature: 80℃. Gas chromatographic conditions are shown in Table 7.

[0063] Table 7 Gas Chromatography Conditions

[0064] 5.2.5 IMS Conditions Ionization source: tritium source (3H); migration tube length: 53 mm; electric field strength: 500 V / cm; migration tube temperature: 45℃; drift gas: high-purity nitrogen (purity ≥99.999%); flow rate: 75.0 mL / min; positive ion mode.

[0065] 5.2.6 Data Processing A mixed standard of six ketones was tested, and calibration curves for retention time and retention index were established. Then, the retention index of the target substance was calculated based on its retention time. The target substance was qualitatively analyzed by searching and comparing the GC retention index (NIST2020) database and the IMS migration time database built into the VOCal software.

[0066] Two-dimensional spectra, differential spectra, fingerprint spectra, and PCA plots of volatile components were generated using plugins such as Reporter, Gallery Plot, and Dynamic PCA in the VOCal data processing software, for comparison of volatile organic compounds between samples.

[0067] 5.2.7 GC-IMS Differential Spectrum Analysis Before and After Deodorization Treatment like Figure 5 As shown, there are certain differences in the volatile organic compounds among different samples. To further visually compare the differences in volatile components among the samples, the spectrum of sample LW28-0001 was selected as a reference, and the spectra of other samples were subtracted from the reference to obtain a comparison chart of the differences between the samples, as shown below. Figure 6 As shown in the figure. If the volatile organic compound (VOC) content in the target sample and the reference sample is the same, the background after subtraction is white. Red indicates that the concentration of the substance in the target sample is higher than that in the reference sample, and blue indicates that the concentration of the substance in the target sample is lower than that in the reference sample. As can be seen from the figure, some VOCs have decreased, indicating that the content of flavor compounds after deodorization treatment is significantly lower than that of frog meat without deodorization.

[0068] 5.2.8 Fingerprint analysis of volatile flavor compounds before and after deodorization treatment Figure 7 The study presents complete information on volatile organic compounds (VOCs) in two groups of samples (LW28-0001, frog meat without deodorization, and LW28-0002, frog meat after deodorization), laying the foundation for subsequent comparative analysis of each VOC component among different samples. The figure clearly shows a significant difference in VOC content between the frog meat before and after deodorization. Specifically: 1) LW28-0001 contains high levels of propionic acid, benzaldehyde, E-2-nonenal, E-2-octenal, Z-4-heptenal, E-2-hexenal, E-2-pentenal, 3-methyl-2-butenal, nonanal, octanal, heptanal, hexanal, pentanal, butanal, propional, 1-octen-3-ol, 1-hexanol, Z-2-penten-1-ol, 1-pentanol, 1-penten-3-ol, 1-propanol, 2-propanol, 1-octen-3-one, 3-octanone, 1-hydroxy-2-propanone, 3-hydroxy-2-butanone, 2-heptanone, 1-penten-3-one, 2-hexanone, 2-pentanone, 2-butanone, acetone, ethyl hexanoate, 2-acetylfuran, 2-pentylfuran, 2,3-dimethylpyrazine, diallyl sulfide, and other substances. 2) LW28-0002 contains high levels of substances such as 3-methyl-1-butanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 2-pentanol, ethanol, 3-octanol, Z-3-hexenol, phenylacetaldehyde, citronellol, 3-methylbutanal, 2-methylpropanal, acetal, 6-methyl-5-hepten-2-one, 3-penten-2-one, isomenthone, 1,8-cineole, ethyl 3-hydroxyhexanoate, o-xylene, and dimethyl sulfide.

[0069] Therefore, compared with the control group, the content of some substances in the frog meat sample decreased after the deodorization treatment, indicating that the deodorization treatment will reduce some of the volatile components in the frog meat, thereby changing its flavor.

[0070] 5.2.9 Classification and peak volume percentage of volatile substances before and after deodorization treatment The volatile components in the samples were determined using GC-IMS technology. A total of 57 volatile components with 72 peaks were identified in the two samples. The detailed list of volatile components is shown in Table 8.

[0071] Table 8. Description of volatile components, peak intensities, and odors in the samples.

[0072] Note: Formula; RI retention index; Rt retention time; Dt migration time; RIPrel indicates normalization of RIP; numbers indicate unidentified signal peaks.

[0073] Further analysis of Table 8 reveals a comparative analysis of volatile substances in frog meat before and after deodorization (Table 9). Table 9 shows that the deodorization treatment significantly altered the odor characteristics of the frog meat. On one hand, the amount of fishy-smelling substances decreased significantly, particularly aldehydes (especially short-chain aldehydes such as hexanal, pentanal, and propionaldehyde). These substances are the main components of aquatic fishy odor; for example, hexanal originates from fat oxidation, and propionaldehyde has a strong pungent odor. The content of sulfur-containing compounds (such as diallyl sulfide) also decreased, reducing the typical characteristics of "fishy smell." On the other hand, aroma compounds were reconstructed. The addition or increased content of alcohols (such as 3-methyl-1-butanol), ketones (isomenthone), and terpenes (citronellol, 1,8-cineole) provided fruity, refreshing, and herbal aromas, forming a new aroma balance and masking the residual fishy smell. The increase in esters (such as ethyl 3-hydroxyhexanoate) and pyrazines (2,3-dimethylpyrazine) brought fruity and nutty aromas, enhancing the flavor complexity. Before deodorization, frog meat primarily exhibited a "fatty, pungent, and grassy" odor; after deodorization, it shifted to a "fruity, refreshing, and herbal" aroma, meeting the deodorization objective. In summary, the deodorization treatment significantly reduced the content of volatile substances related to fishy odor (aldehydes, sulfur-containing compounds) in frog meat and optimized the odor characteristics by generating or enriching aroma compounds such as alcohols, ketones, and terpenes, thus verifying the effectiveness of the deodorization process.

[0074] Table 9. Comparative Analysis of Volatile Compounds in Frog Meat Before and After Deodorization

[0075] In this context, the suffixes M and D represent the monomer and dimer of the same substance, respectively.

[0076] The optimal deodorization process for frog meat determined by this patent is as follows: a coriander-mint compound deodorizing solution with a mass concentration of 3 g / 100 mL, a treatment time of 50 min, and a material-to-liquid ratio of 1:5. Thiobarbituric acid (TBA) values ​​were measured before and after the deodorization treatment of the frog meat. The decrease in malondialdehyde (MDA) content indicated a reduction in TBA values ​​and a decrease in the content of lipid oxidation products. This demonstrates that the deodorization process employed in this patent has a certain inhibitory effect on lipid oxidation in frog meat and can improve its quality to some extent. Analysis of volatile substances in frog meat before and after deodorization using gas chromatography-ion mobility spectrometry (GC-IMS) revealed that alcohols and aldehydes are the main sources of the fishy smell in frog meat, and their content was significantly reduced after deodorization.

[0077] Comparative Example 1 The only difference between Comparative Example 1 and the optimal process in Example 1 is that coriander was not added, and the amount of coriander was replaced with an equal amount of mint leaves. The sensory evaluation and volatile matter content of the frog meat treated in Comparative Example 1 were performed using the method of Example 1, and the results are shown in Tables 10 and 11.

[0078] Table 10 Sensory scores of frog meat before and after treatment in Comparative Example 1

[0079] Table 11 Comparative Analysis of Volatile Compounds in Frog Meat Before and After Treatment in Comparative Example 1

[0080] According to the results analysis, the sensory properties and volatile substances of the frog meat were improved after the deodorization treatment by using peppermint leaves alone, but there was still a large difference compared with Example 1.

[0081] Comparative Example 2 The only difference between Comparative Example 1 and the optimal process in Example 1 is that coriander is replaced with scallions in equal amounts, and mint leaves are replaced with ginger in equal amounts; that is, traditional deodorizing foods are used for deodorization. Sensory evaluation and volatile matter detection were performed on the frog meat treated in Comparative Example 2 using the method of Example 1. The results are shown in Tables 12 and 13.

[0082] Table 12 Sensory scores of frog meat before and after treatment in Comparative Example 2

[0083] Table 13 Comparative Analysis of Volatile Compounds in Frog Meat Before and After Treatment in Comparative Example 2

[0084] According to the results analysis, the sensory quality of frog meat processed using existing technology before and after deodorization is far inferior to that of the processing method in Example 1, and the removal effect of volatile substances is also poor.

[0085] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0086] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for removing the fishy smell from frog meat, characterized in that, Includes the following steps: S1. Raw material pretreatment: Take the leg muscles of the forest frog, cut them into chunks, soak them in water to keep them fresh, and set aside. S2. Preparation of compound deodorizing liquid: Wash and drain the coriander and mint leaves, cut them into pieces and crush them, mix the crushed coriander and mint leaves in a certain proportion to obtain a mixture, add water to soak, filter after soaking to obtain compound deodorizing liquid; S3. Deodorization treatment: Immerse the pre-treated frog meat pieces in the compound deodorization solution prepared in step S2 and soak to remove the fishy smell. In step S2, the mass ratio of coriander to mint leaves is 1:2~4, and the ratio of the mixture to water is 1~5g:100ml; In step S3, the ratio of frog meat chunks to compound deodorizing solution is 1g:3~8ml, and the soaking time for deodorizing is 20~60min.

2. The method according to claim 1, characterized in that, In step S2, the mass ratio of coriander to mint leaves is 1:3, and the ratio of the mixture to water is 3g:100ml.

3. The method according to claim 1, characterized in that, In step S3, the soaking time for deodorizing is 50 minutes.

4. The method according to claim 1, characterized in that, In step S3, the ratio of frog meat chunks to compound deodorizing solution is 1g:5ml.

5. The method according to claim 1, characterized in that, In step S1, the size of the meat pieces is 0.5cm×0.5cm~1.5cm×1.5cm, and the water temperature is 0~8℃; In step S2, the fragment length is 0.5~1.5cm.

6. The method according to any one of claims 1-5, characterized in that, In step S2, the mass ratio of coriander and mint leaves is 1:3, and the ratio of the mixture to water is 3g:100ml; In step S3, the ratio of frog meat chunks to compound deodorizing solution is 1g:5ml, and the soaking time for deodorizing is 50min.

7. Forest frog meat prepared by any one of the methods described in claims 1 to 6.

8. The use of the frog meat according to claim 7 in the preparation of frog jerky, frog meat preserves, quick-frozen frog meatballs, ready-to-eat frog meat snacks, and quick-frozen prepared frog meat products.

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