Processing method for improving muscle quality of rana nigromaculata and application thereof

Abstract

The invention provides a processing method for improving the muscle quality of rana nigromaculata and application of the processing method, and particularly belongs to the technical field of food processing. The invention provides a rana nigromaculata processing method, which comprises: marinating rana nigromaculata, and carrying out vacuum packaging to obtain vacuum packaged rana nigromaculata; cooking the rana nigromaculata packaged in vacuum at low temperature to obtain the rana nigromaculata; the temperature of the low-temperature cooking is 65-95 DEG C; the low-temperature boiling time is 0.5 to 7 hours. According to the processing method disclosed by the invention, the muscular tissue structure of the rana nigromaculata can be well maintained, the water binding capacity is increased, the delicate flavor is improved, more volatile flavor substances are effectively reserved, the product value is improved, and actual economic benefits are generated for enterprises.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a processing method for improving the muscle quality of black-spotted frog and an application thereof. Background Art

[0002] The scientific name of the black-spotted frog is Pelophylax nigromaculatus. It is an amphibian belonging to the phylum Chordata, class Amphibia, order Anura, family Ranidae, and genus Pelophylax. As a seasonal food, the black-spotted frog has tender meat and delicious taste. It is rich in high-quality protein, a variety of umami amino acids, unsaturated fatty acids, vitamins and other nutrients. It is easily absorbed and utilized by the human body and has extremely high nutritional value. It is sought after by people, but compared with other animal meat tissues, the tissue water content is higher, exceeding 75%, the structure is loose, and the water loss is serious during processing. In addition, the unsaturated fatty acids it is rich in are very easy to oxidize during processing, making it more prone to corruption.

[0003] At present, high temperature and high pressure ripening and sterilization methods are often used in the processing of aquatic leisure foods, although the processing time is short. However, the high processing temperature seriously damages the muscle structure of the black-spotted frog, causing a large amount of water loss, protein denaturation, and irreversible changes in the muscle structure; it also produces harmful carcinogens such as acrylamide and polycyclic aromatic hydrocarbons. Not only does it make the meat of the product dry and astringent, but the reduced water content of the finished product will also affect consumers' evaluation of the product and ultimately affect the selling price. At the same time, the loss of umami amino acids also makes it difficult to maintain the "fresh" characteristics of the black-spotted frog. It can only be covered up with a variety of seasonings and food additives such as "heavy oil, heavy salt, and heavy spicy". Not only does it have a single taste and a poor taste, it is also not good for the health of consumers.

[0004] At present, there is no current national standard for the processing of black-spotted frogs. Most companies still process black-spotted frogs according to the standards of other frogs such as bullfrogs. Bullfrogs are large and have rough meat, and lack umami flavor. Applying the processing standards of bullfrogs to black-spotted frogs will not only make it difficult to reflect the characteristics of the black-spotted frog's tender meat, but will also cause unnecessary waste in production and increase production costs. Therefore, there is a lack of a processing method that can improve the muscle quality of black-spotted frogs. Summary of the invention

[0005] The purpose of the present invention is to provide a processing method for improving the muscle quality of black-spotted frog and its application. The processing method of the present invention can better maintain the muscle tissue structure of black-spotted frog, increase water holding capacity, improve umami taste, effectively retain more volatile flavor substances, improve product value, and generate actual economic benefits for enterprises.

[0006] The present invention provides a method for processing black-spotted frog, comprising the following steps:

[0007] braising the black-spotted frog and vacuum-packing it to obtain vacuum-packed black-spotted frog;

[0008] The vacuum-packed black-spotted frog is low-temperature cooked to obtain the black-spotted frog; the low-temperature cooking temperature is 65-95° C.; the low-temperature cooking time is 0.5-7 hours.

[0009] Preferably, the vacuum packaging conditions include: maintaining the vacuum degree at -95 kPa for 30 to 60 seconds and sealing.

[0010] Preferably, the braising comprises: mixing the black-spotted frog with braising liquid for braising.

[0011] Preferably, the marinating conditions are: marinating at 4° C. for 8 to 12 hours.

[0012] Preferably, the mass ratio of the number of black-spotted frogs to the marinade is 1: (7-10) g.

[0013] Preferably, the marinade comprises the following raw materials for preparation in parts by weight: 1500-2000 parts of water, 400-600 parts of extremely fresh soy sauce, 200-300 parts of pickled peppers, 200-300 parts of lemon slices, 100-150 parts of minced garlic, 50-75 parts of shredded ginger, 50-75 parts of chicken powder, 50-75 parts of oyster sauce and 30-45 parts of pepper oil.

[0014] Preferably, the low temperature cooking temperature is 72-76° C.; the low temperature cooking time is 45-60 min.

[0015] The present invention also provides application of the processing method described in the above technical solution in improving the muscle quality of black-spotted frog and / or enhancing the umami taste.

[0016] Preferably, the improving the muscle quality of black-spotted frog includes maintaining the muscle tissue structure of black-spotted frog and / or improving the water retention of muscle; the improving the water retention of muscle includes increasing the water retention of muscle and increasing the water content of muscle.

[0017] The present invention also provides application of the processing method described in the above technical solution in effectively retaining volatile flavor substances of black-spotted frog.

[0018] The present invention provides a processing method for improving the quality of black-spotted frog muscle. The processing method of the present invention is a vacuum low-temperature slow cooking processing method. The black-spotted frog muscle prepared by the processing method of the present invention has a higher water content, stronger water retention of the muscle, and a high sensory evaluation score, especially taste, color and appearance, which have significant advantages compared with the control group; in addition, the electronic tongue results show that the black-spotted frog muscle obtained by the processing method of the present invention has a stronger umami taste, far exceeding the traditional braising method; and the processing method of the present invention detects more volatile flavor substances, which are 56, while the control group only detects 32, the control group has a single flavor, and the black-spotted frog prepared by the processing method of the present invention has a richer flavor; finally, the flavor nucleotide results show that the content of the flavor nucleotide of the present invention is greater than that of the control group, and the TAV value is significantly improved. The umami taste of the black-spotted frog obtained by the processing method of the present invention is better than that of the traditional braising group. The better moisture content and product flavor of the present invention can actually improve the product value and generate actual economic benefits for the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 The moisture content result diagram provided by the present invention;

[0021] Figure 2 The water holding capacity result diagram provided by the present invention;

[0022] Figure 3 A sensory score radar chart provided by the present invention;

[0023] Figure 4 This is the electronic tongue radar diagram provided by the present invention. DETAILED DESCRIPTION

[0024] The present invention provides a method for processing black-spotted frog, comprising the following steps:

[0025] braising the black-spotted frog and vacuum-packing it to obtain vacuum-packed black-spotted frog;

[0026] The vacuum-packed black-spotted frog is low-temperature cooked to obtain the black-spotted frog; the low-temperature cooking temperature is 65-95° C.; the low-temperature cooking time is 0.5-7 hours.

[0027] The present invention stews black-spotted frogs and vacuum packs them to obtain vacuum-packed black-spotted frogs. The present invention further includes pre-treating the black-spotted frogs before stewing. In a specific embodiment, the pre-treatment includes peeling, removing internal organs, soaking and cleaning. The present invention has no special provisions for pre-treatment, and conventional methods can be used. In a specific embodiment, the stewing includes: mixing the black-spotted frogs with marinade for stewing. In a specific embodiment, the stewing conditions are: marinating at 4°C for 8 to 12 hours. In a specific embodiment, the mass ratio of the number of the black-spotted frogs to the marinade is 1: (7 to 10) g. In a specific embodiment, the marinade includes the following raw materials for preparation in parts by weight: 1500-2000 parts of water, 400-600 parts of extremely fresh soy sauce, 200-300 parts of pickled peppers, 200-300 parts of lemon slices, 100-150 parts of minced garlic, 50-75 parts of shredded ginger, 50-75 parts of chicken powder, 50-75 parts of cooking oil and 30-45 parts of pepper oil. The marinade of the present invention can remove fishy smell, enhance freshness and flavor. After the raw materials of the marinade of the present invention are mixed, they are soaked at 4°C for 1-2 hours to obtain a marinade product. In a specific embodiment, the vacuum packaging conditions include: maintaining a vacuum degree of -95kpa for 30-60s and sealing. The present invention adds the marinade and the black-spotted frog into a vacuum bag, seals it and heats it. The vacuum environment can accelerate the marinade to enter the meat and improve the efficiency of marinating. At the same time, the vacuum bag can be directly used as the packaging of the product, which can not only intuitively reflect the color and appearance of the final product. Its good sealing properties can also protect the black-spotted frog from contact with the outside air, effectively avoiding secondary contamination during food storage and extending the shelf life.

[0028] After obtaining the vacuum-packed black-spotted frog, the present invention performs low-temperature cooking on the vacuum-packed black-spotted frog to obtain the black-spotted frog; the temperature of the low-temperature cooking is 65-95°C; the time of the low-temperature cooking is 0.5-7h. Processing within the above temperature and time range, the product has less nutritional loss, good sensory properties, and can also achieve the effect of inactivating enzymes and microorganisms in traditional processing, and retain the juice in the black-spotted frog muscle without loss; below 65°C, the meat cannot be fully mature, and above 95°C, the appearance, color and taste are poor. The lower processing temperature has less damage to proteins and amino acids, which can not only maintain the integrity of the muscle structure and improve the water retention of the black-spotted frog muscle, but also reduce the loss of volatile flavor substances and increase the umami taste. In a specific embodiment, the temperature of the low-temperature cooking is 72-76°C; the time of the low-temperature cooking is 45-60min. Under the above temperature and time of the present invention, the obtained black-spotted frog meat has better quality. In a specific embodiment, after the low-temperature cooking, the present invention also includes cooling. In a specific embodiment, the cooling includes spraying to cool down to room temperature. The room temperature in the present invention refers to 20-25°C.

[0029] The present invention also provides the use of the processing method described in the above technical solution in improving the muscle quality of black-spotted frog and / or improving the umami taste. In a specific embodiment, the improvement of the muscle quality of black-spotted frog includes maintaining the muscle tissue structure of black-spotted frog and improving the water retention of the muscle; the improvement of the water retention of the muscle includes increasing the water retention of the muscle and increasing the water content of the muscle. The black-spotted frog muscle prepared by the processing method of the present invention has a higher water content and a stronger water retention of the muscle. The black-spotted frog muscle obtained by the processing method of the present invention has a richer umami taste, far exceeding the traditional braising method.

[0030] The present invention also provides the use of the processing method described in the above technical solution in effectively retaining the volatile flavor substances of black-spotted frog. The processing method of the present invention detected more volatile flavor substances, 56 kinds, while the control group only detected 32 kinds, and the flavor of the control group was single. The black-spotted frog prepared by the processing method of the present invention has a richer flavor.

[0031] In order to further illustrate the present invention, a processing method for improving the muscle quality of black-spotted frog provided by the present invention and its application are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0032] Example 1

[0033] The black-spotted frog products are processed by vacuum low-temperature slow cooking. The details are as follows:

[0034] (1) Preparation of marinade

[0035] Mix 1500g water, 400g Wei Ji Xian soy sauce, 200g pickled peppers, 200g lemon slices, 100g minced garlic, 50g shredded ginger, 50g chicken powder, 50g oyster sauce and 30g Sichuan pepper oil, and soak at 4°C for 2h to make the marinade.

[0036] (2) Pretreatment of black-spotted frog raw materials

[0037] The freshly slaughtered black-spotted frogs were skinned and visceralized, and the processed black-spotted frogs were placed in a flowing clear water pool for 2 hours to soak and remove blood. The processed black-spotted frogs were then washed clean of dirt, and placed in a food-grade high-temperature resistant vacuum bag with a pre-prepared marinade at a ratio of 10 black-spotted frogs to 100g of marinade for vacuum sealing for standby use, and the vacuum condition was to maintain a vacuum degree of -95kpa for 60s and then thermoplastic seal. The pre-processed and sealed black-spotted frog product to be processed was obtained.

[0038] (3) Low temperature pickling

[0039] The black-spotted frog product to be processed, which has been pre-sealed with marinade, is placed in a 4°C refrigerator and marinated at low temperature for 12 hours.

[0040] (4) Low temperature slow cooking

[0041] The pre-treated and sealed black-spotted frog product is placed in a preheated low-temperature slow-cooking water tank and cooked for 45 to 60 minutes at 72 to 76° C. After the heat treatment is completed, the product is sprayed to cool down to room temperature to obtain the final product.

[0042] Specific experimental group and control group conditions

[0043] Experimental group 1: food-grade vacuum bag packaging, processing time: 45 min, processing temperature: 76°C, feed-liquid ratio: 100 g marinade for every 10 black-spotted frogs and white-striped frogs;

[0044] Experimental group 2: food-grade vacuum bag packaging, processing time: 60 min, processing temperature: 76°C, feed-liquid ratio: 100 g marinade for every 10 black-spotted frogs and white-striped frogs;

[0045] Experimental group 3: food-grade vacuum bag packaging, processing time: 45 min, processing temperature: 72°C, feed-liquid ratio: 100 g marinade for every 10 black-spotted frogs and white-striped frogs;

[0046] Experimental group 4: food-grade vacuum bag packaging, processing time: 45 min, processing temperature: 72°C, feed-liquid ratio: 75 g marinade for every 10 black-spotted frogs and white-striped frogs;

[0047] Traditional stewed control group 1: No vacuum packaging was performed, and the frogs were directly boiled in 100℃ boiling water for 15min. After the heat treatment, the frogs were placed in the stewed sauce at 4℃ for 12h.

[0048] Traditional stewed control group 2: No vacuum packaging was performed, the black-spotted frogs were cooked in a 100°C stew for 15 min, and then the stewed black-spotted frogs and the stew were stewed at 4°C for 12 h.

[0049] Evaluation of key indicators of vacuum low-temperature slow cooking processing black-spotted frog products

[0050] Moisture content determination:

[0051] The test adopts GB 5009.3-2016 "National Food Safety Standard Determination of Water in Food". The constant weight of the aluminum box is recorded as m 3 Take the final product, chop it up and take 5.00g, put it in an aluminum box, cover it, and weigh it accurately. The mass is recorded as m 1 Place in a 105℃ drying oven, with the bottle cap tilted on the side of the bottle, dry for 4 hours, cover and take out, put in a dryer to cool for 0.5 hours, and weigh. Repeat the above operation until the difference between the two masses does not exceed 2 mg, which is a constant weight, recorded as m 2 The moisture content in the sample is calculated according to formula (1):

[0052]

[0053] Where:

[0054] X——water content in the sample, in g / 100g;

[0055] m 1 ——The mass of the weighing bottle and the sample, in g;

[0056] m 2 ——The mass of the weighing bottle and the sample after drying, in g;

[0057] m 3 ——The mass of the weighing bottle, in g.

[0058] (When the moisture content is ≥1g / 100g, the calculation result shall be rounded to three significant figures; when the moisture content is <1g / 100g, the calculation result shall be rounded to two significant figures).

[0059] The results were compared with those obtained by traditional braising.

[0060] Determination of water holding capacity:

[0061] Take the final product, chop it into pieces to get about 10g of minced frog meat, and weigh it accurately (m 1 , accurate to 0.0001g). Put absorbent cotton in the centrifuge tube, wrap the minced frog meat with two layers of filter paper and put it in the centrifuge tube. After accurate balancing, centrifuge at 20℃ and 5000r / min for 25min, control the water on the filter paper for 30min, and then accurately weigh the weight of the frog meat after centrifugation (m 2 , accurate to 0.0001g). The water holding capacity is calculated according to formula (2):

[0062]

[0063] Where:

[0064] X——water holding capacity, in %;

[0065] m 1 ——The mass of black-spotted frog meat before centrifugation, in g;

[0066] m 2 ——The mass of black-spotted frog meat after centrifugation, in g;

[0067] Determination of texture:

[0068] The frog leg meat was cut into cylinders with a diameter of 2.0 cm and a height of 2.0 cm, and the texture profile analysis (TPA) mode was used to determine the texture characteristics of the processed black-spotted frog meat. The test conditions were as follows: P / 36R flat-bottomed cylindrical probe; pre-test rate 2 mm / s; test rate 5 mm / s; post-test rate 5 mm / s; compression degree 50%; dwell time between two compressions 5s; trigger type automatic; trigger force 10g. Hardness, springiness, cohesiveness, gumminess, and chewiness were selected as evaluation indicators.

[0069] Sensory Rating:

[0070] Table 1 Sensory rating table

[0071]

[0072]

[0073] According to the information in the sensory evaluation table in Table 1, the product quality is scored.

[0074] Electronic tongue:

[0075] Preheat the water bath to 40℃, add 200mL of pure water to the beaker and put it into the 40℃ water bath (with plastic wrap attached to the beaker mouth), take out the complete thigh meat from the finished products of the 6 groups, accurately weigh 50g of frog leg meat from each group, put it into the meat grinder and stir for 1min, then add 4 times the volume of pure water (40℃ insulation) and stir for 1min, divide the meat and water mixture into equal weights and centrifuge it at 3000r / min for 10min, let it stand, wait for the two phases to separate obviously, take out the supernatant and filter it several times, which is the sample solution to be tested, cool it to room temperature and then test it on the machine. Set the test conditions as follows: take the raw black-spotted frog sample as the reference solution. Place the sensor in the reference solution and return it to zero for 30s, then start the umami test. The test time is 30s, and after the test, wash it with the reference solution for 3s, and then perform the aftertaste test again for 30s. Repeat each sample 4 times, and take the last 3 times as the test result.

[0076] GC-MS volatile flavor compounds detection:

[0077] HS-SPME conditions: 4 g of minced braised black-spotted frog thigh meat and 2-methyl-3-heptanone (1.68 μg / μL, 1.5 μL) were added to a 20 ml headspace vial. The sample was incubated at 55°C for 10 min, extracted with the HS-SPME injection needle for 45 min, and then desorbed at 250°C for 3 min in splitless mode.

[0078] GC-MS conditions: chromatographic column: HP-5MS quartz capillary column (30m×0.25mm, 0.25μm); injection port temperature: 250℃. Temperature program: 40℃ for 3min, 2℃ / min to 70℃, 3℃ / min to 130℃, 10℃ / min to 230℃, and hold for 10min. Carrier gas (He) flow rate: 1.0mL / min; ionization mode: electron ionization: electron energy: 70eV; transfer line temperature: 280℃; ion source temperature: 200℃; mass scanning range: m / z 50-450.

[0079] Qualitative and quantitative analysis: The test used MS spectral library (NIST17-1.lib) similarity search for qualitative analysis, retaining compounds with a matching degree of more than 80, and using the peak area normalization method to calculate the relative content of volatile flavor substances.

[0080] Flavor nucleotide detection: Sample preparation and pretreatment: Accurately weigh 5 g of stewed and cooled black-spotted frog thigh meat into a 50 ml centrifuge tube, add 10 ml of 5% HClO precooled in a 4°C refrigerator for 40 min, 4 The solution was homogenized and centrifuged at 10000r / min for 10min at 4℃. The supernatant was taken and placed in another centrifuge tube. The above steps were repeated to combine the supernatants from the two centrifuges. The pH was adjusted to 6.5 with 1mol / L KOH solution, and the volume was made up to 50ml with ultrapure water. The solution was centrifuged again at 10000r / min for 10min at 4℃. 1ml of the supernatant was filtered through a 0.22μm aqueous filter membrane for HPLC analysis.

[0081] Liquid chromatography conditions: Column: C 18 Reverse phase chromatography column; mobile phase is KH 2 PO 4 :K 2 HPO 4 Solution (0.025 mol / L, pH 6.5) (1:1, V / V); flow rate 0.5 ml / min; isocratic sequential elution 30 min; detection wavelength 260 nm; injection volume 10 μL; column temperature 40°C.

[0082] result

[0083] 1. Moisture content

[0084] The moisture content results are as follows Figure 1 As shown, from Figure 1 It can be seen that the moisture content of the black-spotted frog muscle processed by vacuum low-temperature slow cooking is significantly higher than that of the traditional stewed control group, and the increase rate is 9.97% compared with the control group. This proves that the black-spotted frog muscle processed by vacuum low-temperature slow cooking has a higher moisture content.

[0085] 2. Water holding capacity

[0086] The water holding capacity results are as follows Figure 2 As shown. Figure 2 It can be seen that the water holding capacity of the black-spotted frog muscles in each group treated with vacuum low-temperature slow cooking was significantly improved compared with the traditional marinated control group, and the improvement rate reached 33.82% compared with the control group, proving that the black-spotted frog muscles processed by vacuum low-temperature slow cooking have stronger water holding capacity.

[0087] 3. Texture

[0088] Table 2 Texture

[0089] Group Hardness / gf elasticity Chewability / gf Cohesion Experimental Group 1 <![CDATA[289.51±23.42 c ]]> <![CDATA[0.75±0.02 a ]]> <![CDATA[130.68±10.48 b ]]> <![CDATA[0.60±0.50 b ]]> Experimental Group 2 <![CDATA[267.12±25.76 d ]]> <![CDATA[0.72±0.05 a ]]> <![CDATA[121.83±12.78 b ]]> <![CDATA[0.64±0.06 b ]]> Experimental Group 3 <![CDATA[272.92±10.76 d ]]> <![CDATA[0.72±0.12 a ]]> <![CDATA[130.25±10.98 b ]]> <![CDATA[0.66±0.13 b ]]> Experimental Group 4 <![CDATA[270.08±32.91 d ]]> <![CDATA[0.69±0.09 a ]]> <![CDATA[125.46±2.67 b ]]> <![CDATA[0.68±0.08 b ]]> Control group 1 <![CDATA[365.69±25.01 b ]]> <![CDATA[0.48±0.10 b ]]> <![CDATA[192.63±8.91 a ]]> <![CDATA[1.10±0.09 a ]]> Control group 2 <![CDATA[391.32±23.00 a ]]> <![CDATA[0.45±0.11 b ]]> <![CDATA[204.30±11.76 a ]]> <![CDATA[1.16±0.07 a ]]>

[0090] The texture characteristics can directly reflect the changes in the tissue structure characteristics of the hind leg muscles of the black-spotted frog after vacuum low-temperature slow cooking. Table 2 shows the texture changes of different experimental groups and control groups. It can be seen that the hardness, chewiness, and cohesion of the experimental group treated with vacuum low-temperature slow cooking are significantly lower than those of the traditional stewed control group, while the elasticity value is significantly higher than that of the control group. This shows that the black-spotted frog meat that has been stewed with vacuum low-temperature slow cooking has a better chewy feeling and excellent elasticity, and has a better tissue structure than the traditional stewed processing.

[0091] 4. Sensory evaluation

[0092] Sensory score radar chart Figure 3 The sensory evaluation score table is shown in Table 3.

[0093] Table 3 Sensory evaluation score table

[0094] Group taste odor Taste Color Appearance Experimental Group 1 8.93 9 9.43 9.29 6.29 Experimental Group 2 8.36 8.79 8.5 7.93 6.5 Experimental Group 3 6.5 8.57 8.71 8.57 7.43 Experimental Group 4 8.36 8.5 8.5 8.64 4.64 Control group 1 8.64 8.43 0.29 1.86 0.43 Control group 2 8.7 9.4 0.3 3.6 1

[0095] Figure 3 In the table, the area of ​​each group represents the score of the corresponding group. It can be seen that the total scores of the experimental groups are greater than those of the control group, indicating that the scores of the black-spotted frogs processed by vacuum low-temperature slow cooking technology are greater than those of the traditional stewed control group. According to Table 3, although the taste and smell scores of the traditional stewed control group are better, the appearance, color and taste of the frogs after processing are worse than those of the experimental group.

[0096] 5. Electronic tongue

[0097] Figure 4 The electronic tongue radar chart can objectively draw the difference between different groups through the analysis of electronic sensory organs. Figure 4 It can be seen that the specific flavor types of each experimental group and the control group are basically the same. However, the umami value of the experimental group far exceeds that of the control group, while the saltiness and bitterness are just the opposite. This shows that the umami taste of the black-spotted frog muscle processed by vacuum low-temperature slow cooking technology is more intense, far exceeding the traditional braising method.

[0098] 6.GC-MS

[0099] The results are shown in Table 4.

[0100] Table 4 Volatile flavor substances

[0101]

[0102]

[0103]

[0104] From Table 4, we can see the main volatile flavor substances of each group, among which the bold ones are key flavor substances with higher content, while the underlined ones are the main volatile flavor substances, which are second in content but still the main substances of product flavor. A total of 56 volatile flavor substances were detected in the experimental group, of which linalool, myristic aldehyde, diallyl sulfide, D-limonene and sorbic acid were the key flavor substances. Only 32 volatile flavor substances were detected in the control group. Although the content of its main flavor substances was high, they were mainly linalool, citral, D-limonene, sorbic acid, etc., which accounted for a large proportion of the total content of flavor substances in the group. For example, the citral in control group 2 is a flavor substance derived from lemon. Because the heating temperature of the control group is high, the citral in the lemon is released in large quantities, resulting in a high content and a relatively single flavor. Linalool in control group 1 mainly comes from the pickled peppers in the marinade. Also because of the higher marinating temperature, its content is higher than that of other volatile flavor substances, which will make the flavor of the pickled peppers too strong, thus affecting the overall sensory experience of the finished product and covering up the "fresh" characteristics of the black-spotted frog. The flavor substance content of the experimental group is more balanced. For example, volatile flavor substances such as geranyl aldehyde, myricetin, and dianthus oxalis do not decompose in large quantities at a lower marinating temperature. At the same time, the experimental group contains a variety of alkane substances, providing a rich and complex flavor. The overly strong flavor of lemon and pickled peppers will affect the original freshness of the black-spotted frog.

[0105] 7. Flavor nucleotides

[0106] The results are shown in Tables 5 and 6.

[0107] Table 5 Taste characteristics and taste thresholds of flavor nucleotides

[0108] Flavor nucleotides Taste characteristics Taste threshold (mg / 100g) GMP-Guanylate Umami 12.50 IMP-Inosinic Acid Umami 25.00 AMP Umami / Sweetness 50.00

[0109] Table 6 Flavor nucleotide content and TAV value

[0110]

[0111] Table 5 shows the taste characteristics and taste thresholds of flavor nucleotides. Flavor nucleotides are an important source of umami flavor in aquatic products, among which GMP, AMP and IMP are the main sources of umami flavor. Calculating the TAV value of each group based on the taste threshold can better reflect the difference in umami flavor between the groups. As can be seen from Table 6, the content of the three nucleotides in each experimental group is greater than that in the control group, and its TAV value has also increased significantly. It can be considered that the umami flavor of the black-spotted frog processed by vacuum low-temperature slow cooking technology is better than that of the traditional marinated group.

[0112] in conclusion

[0113] Compared with the traditional black-spotted frog processing technology, the processing method of the present invention can better maintain the muscle tissue structure of the black-spotted frog, increase water holding capacity; protect free amino acids, improve umami taste; and better maintain volatile flavor substances. Better moisture content and product flavor can actually improve product value and generate actual economic benefits for the enterprise. The vacuum bag can be used as the final packaging of the product, significantly reducing the processing steps and reducing production costs.

[0114] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for processing black-spotted frog, characterized in that: The following steps are involved: braising the black-spotted frog and vacuum-packing it to obtain vacuum-packed black-spotted frog; The vacuum-packed black-spotted frog is low-temperature cooked to obtain the black-spotted frog; the low-temperature cooking temperature is 65-95° C.; the low-temperature cooking time is 0.5-7 hours.

2. The processing method according to claim 1, characterized in that: The vacuum packaging conditions include: maintaining the vacuum degree at -95 kPa for 30 to 60 seconds and sealing.

3. The processing method according to claim 1, characterized in that: The braising comprises: mixing the black-spotted frog with braising sauce for braising.

4. The processing method according to claim 3, characterized in that: The marinating conditions are: marinating at 4° C. for 8 to 12 hours.

5. The processing method according to claim 3, characterized in that: The mass ratio of the number of black-spotted frogs to the marinade is 1: (7-10) g.

6. The processing method according to claim 3, characterized in that: The marinade comprises the following raw materials in parts by weight: 1500-2000 parts of water, 400-600 parts of extremely fresh soy sauce, 200-300 parts of pickled peppers, 200-300 parts of lemon slices, 100-150 parts of minced garlic, 50-75 parts of shredded ginger, 50-75 parts of chicken powder, 50-75 parts of oyster sauce and 30-45 parts of pepper oil.

7. The processing method according to claim 1, characterized in that: The low temperature cooking temperature is 72-76° C.; the low temperature cooking time is 45-60 minutes.

8. Use of the processing method according to any one of claims 1 to 7 in improving the muscle quality and / or enhancing the umami taste of Rana nigromaculata.

9. The use according to claim 8, characterized in that: The improving of the muscle quality of black-spotted frog includes maintaining the muscle tissue structure of black-spotted frog and / or improving the water retention of muscle; the improving of the water retention of muscle includes increasing the water retention of muscle and increasing the water content of muscle.

10. Use of the processing method according to any one of claims 1 to 7 in effectively retaining volatile flavor substances of Rana nigromaculata.

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