Salt-less sugar-free aquatic food and preparation method thereof

Abstract

The invention discloses a low-salt sugar-free aquatic food and a preparation method thereof, and belongs to the technical field of aquatic food production. According to the method, fishy smell removal and nutrition retention of aquatic food are realized through multiple mechanisms: firstly, a fishy smell removal solution containing a porous cyclodextrin-pomegranate peel ellagic acid compound is adopted, volatile fishy smell substances are removed through physical embedding and an acid-base neutralization reaction, and decomposition of lysozyme on microbial source fishy smell precursors is promoted in combination with dynamic variable-temperature ultrasound; in the pickling stage, white granulated sugar is replaced by resistant dextrin and stevia rebaudiana extract, and high oleic acid camellia oil is matched to form a water-retaining gel layer, so that the loss of DHA in the frying process can be reduced. According to the method, the grease content is reduced by adopting a sectional frying and centrifugal deoiling process, and the oxidation of the fish meat is inhibited by assisting the L-ascorbyl palmitate. The aquatic food prepared by the invention realizes no addition of chemical preservatives, the salt content is greatly reduced compared with the traditional process, and the aquatic food conforms to the health trend of salt reduction, no sugar and natural preservation.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquatic food production, and particularly relates to a low-salt and sugar-free aquatic food and a preparation method thereof. Background Art

[0002] As an important source of high-quality protein and unsaturated fatty acids, aquatic food occupies a key position in the dietary structure. Hairtail and yellow croaker, as representative varieties of China's marine fishery, have a high market share in their processed products. Hairtail, also known as cutlassfish and ribbonfish, is a deep-sea fish widely distributed in the warm and temperate waters of the world and is one of the four traditional major marine products in China. Hairtail is often made into canned food. Hairtail canned food contains rich nutrients such as protein, trace elements, dietary fiber, etc., which can supplement the nutrients needed by the body. Every 100 grams of hairtail contains 17.7 - 18.4 grams of protein, and the amino acid composition is close to the human body's needs. Among them, the contents of lysine, histidine and alanine are relatively high and are easily absorbed. Its fat content is about 4.6 - 7.4 grams / 100 grams, mainly composed of unsaturated fatty acids, especially DHA and EPA, which can reduce cholesterol, promote brain development, delay Alzheimer's disease, and maintain cardiovascular health. The silver fat on the surface of hairtail contains 6-thioguanine, which has an auxiliary prevention and treatment effect on tumors such as leukemia and gastric cancer, and the contained lecithin can delay the aging of brain cells. Yellow croaker, also known as small yellow croaker, is an important economic fish in China's coastal waters. Its meat is delicate and delicious, and it is rich in high-quality protein and Omega-3 fatty acids. Every 100 grams of yellow croaker contains 17.6 - 18.2 grams of protein, and the fat content is about 3.5 - 5.2 grams. Among them, the contents of DHA and EPA account for 25% - 35% of the total fatty acids, which have significant anti-inflammatory and cardiovascular protection effects. Its contents of trace elements such as calcium and selenium are higher than those of most marine fish, and it is suitable for children and the elderly to eat. Both aquatic products have high processing added value and are ideal raw materials for canned aquatic food.

[0003] The processing technologies of traditional aquatic food all rely on high-salt pickling and high-sugar seasoning to extend the shelf life and cover up the fishy smell, which is contrary to the trend of low-sodium and sugar-free health. To remove the fishy smell of aquatic raw materials, high-temperature frying or chemical treatment is mostly used, resulting in the destruction of heat-sensitive nutrients such as DHA and EPA. Due to the fine muscle tissue of fish meat, fishy smell substances (such as trimethylamine oxide) are more likely to accumulate. The traditional process requires a higher salt concentration to suppress the fishy smell, further increasing the risk of excessive sodium intake. In the anti-corrosion process, chemical preservatives such as sodium benzoate are often added, which is contrary to the trend of reducing salt, sugar-free and natural anti-corrosion in food safety. In addition, after high-temperature sterilization of aquatic raw materials, problems such as loose meat quality and flavor loss are likely to occur, restricting the product quality. Therefore, most current aquatic foods are difficult to meet the needs of modern consumers for healthy foods. Developing a processing technology with low salt and sugar, simple fishy smell removal process and able to retain nutrients is of great significance for improving the quality of aquatic food. Summary of the Invention

[0004] In view of the above situation, to overcome the defects of the prior art, the present invention realizes triple mechanism deodorization of adsorption, neutralization and enzymatic hydrolysis through a composite deodorizing liquid, and uses less salt and no sugar during the pickling process, retaining the flavor and color of hairtail and yellow croaker, and avoiding the use of preservatives.

[0005] To achieve the above object, the following technical solutions are adopted: The present invention provides a method for preparing a low-salt and sugar-free aquatic food, comprising the following steps:

[0006] (1) Pretreatment: After removing the heads, tails and internal organs of the fresh aquatic raw materials, first rinse the surface mucus with light brine with a mass percentage of 3-5%, then soak in ice water with a mass percentage of 0.1-0.3% sodium bicarbonate for 3-8 min, and finally treat with an ultrasonic water washer at a frequency of 40 kHz for 2-5 min. After draining, cut into fish pieces 3-5 cm long. The fresh aquatic raw materials include but are not limited to hairtail and yellow croaker;

[0007] (2) Deodorization treatment: Immerse the fish pieces in the composite deodorizing liquid according to the mass ratio of material to liquid of 1:3-1:5, and perform dynamic variable-temperature ultrasonic treatment at 35-45 °C, then rinse and drain;

[0008] The composite deodorizing liquid is composed of the following components by mass percentage: 0.3-0.6% yeast extract, 0.1-0.3% porous cyclodextrin-pomegranate peel ellagic acid complex, 0.02-0.05% lysozyme, 0.01-0.03% L-ascorbic acid 6-palmitate, 3-8% ethanol, and the rest is pure water;

[0009] The porous cyclodextrin-pomegranate peel ellagic acid complex is obtained by dissolving porous cyclodextrin and pomegranate peel ellagic acid in a mass ratio of 1:0.5-2 in an ethanol solution with a volume fraction of 30%, stirring at 40 °C for 4-6 h, and then freeze-drying;

[0010] (3) Pickling: Put the deodorized fish pieces and the pickling material into a vacuum tumbler according to the mass ratio of 10:1-15:1;

[0011] The pickling material is composed of the following components by mass percentage: 5-8% resistant dextrin, 1.5-2.5% stevia extract, 0.8-1.5% low-sodium salt, 2-4% high-oleic acid camellia oil, 1-2% chicken powder, 3-5% oyster sauce, 2-3% cooking wine, 0.3-0.5% pepper powder, 0.5-1.2% compound spice, and the rest is pure water;

[0012] (4) Frying: Specifically includes the following steps:

[0013] Initial frying: Fry the pickled fish pieces in high-oleic acid rapeseed oil at 155-165 °C for 30-45 s;

[0014] Draining: Transfer the fish pieces after the first frying to a vibrating sieve with an amplitude of 3 - 5 mm and a frequency of 50 - 70 times / min for draining for 60 - 120 s;

[0015] Re - frying: Fry in oil at a temperature of 180 - 183 °C for 60 - 90 s, and then process in a centrifugal oil - removing machine at 1200 - 1500 r / min for 1 - 3 min;

[0016] (5) Filling: Load the fried fish pieces and the sauce into a tinplate can, a glass bottle or a high - temperature sterilization bag at a weight ratio of 3:1 - 4:1;

[0017] (6) Exhausting and sealing: Exhaust the filled product and then seal it;

[0018] (7) Sterilizing and cooling: Place the filled product in a sterilization kettle for sterilization and then cool it.

[0019] Among them, the hydrophobic cavity of porous cyclodextrin fixes volatile fishy smell substances such as hexanal and heptanal in fish meat through physical embedding. The phenolic hydroxyl group in punicalagin reacts with trimethylamine (one of the main components of fishy smell) to undergo an acid - base neutralization reaction, generating non - volatile salts and reducing the intensity of fishy smell. The porous structure can protect the antioxidant activity of ellagic acid and delay the off - flavor generated by the oxidation of fish meat fat.

[0020] Resistant dextrin and stevia extract, as dietary fiber - type sugar substitutes, provide adhesiveness and water - retention similar to granulated sugar, avoid the browning reaction caused by traditional high - sugar formulations, form a gel layer on the surface of fish pieces, reduce water loss and oil penetration during frying, and maintain the tenderness of fish meat. Resistant dextrin is not absorbed by the small intestine, and stevia extract, as a prebiotic, both meet the blood sugar control requirements of sugar - free foods.

[0021] High - oleic acid camellia oil reduces the generation of trans - fatty acids during frying, is superior to ordinary vegetable oils. As a fat - soluble medium, it promotes the penetration of spices such as rosemary and garlic powder, enhances the effect of removing fishy smell and increasing fragrance, and at the same time reduces the thermal oxidation loss of unsaturated fatty acids such as DHA and EPA, maintaining the nutritional value of fish meat.

[0022] L - ascorbic acid 6 - palmitate enhances its stability in the oil system through esterification modification, inhibits the oxidative rancidity of fat during frying and storage, and can also chelate metal ions (such as iron and copper) to prevent the color deterioration caused by the oxidation of myoglobin in fish meat.

[0023] Furthermore, the ultrasonic parameters of the dynamic variable - temperature ultrasonic treatment are: dual - frequency alternation, the main frequency is 28 kHz, the auxiliary frequency is 68 kHz, and the power density is 300 - 500 W / m 2 , first heat up to 35 °C, keep warm for 5 - 8 min, then heat up to 42 °C, keep warm for 5 - 8 min, and finally cool down to 38 °C, keep warm for 10 - 15 min.

[0024] The cavitation effect is generated by dual-frequency alternating ultrasonic waves to promote the penetration of the deodorizing components deep into the muscle fibers. The binding force between the fishy substances and proteins is destroyed by varying the temperature, and the decomposition efficiency of lysozyme on the microbial-source fishy precursors is improved.

[0025] Furthermore, the working parameters of the vacuum tumbler are as follows: under a pressure of -0.08 to -0.1 MPa, an intermittent tumbling mode is adopted, with 5 minutes of forward rotation, 5 minutes of standing still, 5 minutes of reverse rotation, and a total duration of 45 - 60 minutes.

[0026] Furthermore, the compound spice is composed of rosemary powder, garlic powder, and clove extract in a mass ratio of 4 - 6:1.5 - 2:1.

[0027] Among them, carnosic acid in rosemary powder and eugenol in clove extract have broad-spectrum antibacterial effects and can replace chemical preservatives. The sulfides in garlic powder and rosemary terpenoids form a compound aroma to mask the residual fishy smell.

[0028] Furthermore, the sauce is composed of the following components in parts by mass: 80 - 85 parts of softened water, 8 - 12 parts of sugar-free natural sweetener, and 5 - 8 parts of vinegar; the sugar-free natural sweetener is selected from one or more of monk fruit powder, glycyrrhizin, stevioside, mannitol, and hesperidin.

[0029] Furthermore, in the exhaust process, the temperature is raised to 90 - 95 °C at a rate of 1 - 2 °C / min. After maintaining the center temperature of the can ≥ 85 °C, the vacuum is pumped to 0.04 - 0.06 Mpa.

[0030] Furthermore, for the filling step, glass bottles or high-temperature sterilization bags can be used for filling. When using glass bottles for filling, the exhaust and sealing step uses vacuum pumping to exhaust the glass bottles and then seals them. When using high-temperature sterilization bags for filling, the exhaust and sealing step uses vacuum heat sealing to exhaust and seal the high-temperature sterilization bags.

[0031] Furthermore, when using a tinplate can for the filling step, progressive heating is used to exhaust the tinplate can and then seal it;

[0032] In the exhaust process, the temperature is raised to 90 - 95 °C at a rate of 1 - 2 °C / min. After maintaining the center temperature of the can ≥ 85 °C, the vacuum is pumped to 0.04 - 0.06 Mpa;

[0033] The sterilization temperature is 115 - 121 °C, and the sterilization time is 10 - 15 minutes;

[0034] The cooling process is carried out in three stages for segmented cooling as follows:

[0035] Cool from 100 °C to 80 °C, and cool down with water spraying for a duration of 4 - 6 minutes;

[0036] Cool from 80°C to 50°C, cool by air with a wind speed of 3 - 5 m / s for 6 - 10 min;

[0037] Cool from 50°C to room temperature, let it stand for cooling for 20 - 30 min.

[0038] Further, when the filling step uses glass bottles for filling, in the exhaust sealing step, vacuum pumping is used to exhaust the glass bottles and then seal them;

[0039] The sterilization temperature is 105 - 110°C, the sterilization time is 8 - 12 min, and the pressure in the sterilization kettle is 0.12 - 0.15 MPa;

[0040] The cooling step uses segmented water cooling, cooling from 70°C to 40°C in sequence, and then to 25°C. The total cooling time is 20 - 25 min, and a back pressure of 0.1 - 0.12 MPa is applied.

[0041] Further, when the filling step uses high - temperature sterilization bags for filling, in the exhaust sealing step, vacuum heat sealing is used to exhaust and seal the high - temperature sterilization bags. The sterilization temperature is 135°C, the sterilization time is 3 - 5 min, and the pressure in the sterilization kettle is 0.25 - 0.3 MPa;

[0042] The cooling step uses a combination of pressurized air cooling and cold water spraying. The cooling time is 8 - 10 min, and a stepped pressure reduction is implemented during the cooling stage, reducing 0.05 MPa every 2 min. On the other hand, the present invention also provides a low - salt and sugar - free aquatic food product prepared by the described preparation method.

[0043] The beneficial effects of the present invention are:

[0044] (1) In the present invention, pomegranate peel ellagic acid is loaded by porous cyclodextrin. The volatile fishy substances such as hexanal are included in the nanoscale pores of cyclodextrin and fixed by hydrophobic interaction. The pomegranate peel ellagic acid contains active sites such as phenolic hydroxyl groups, which can undergo acid - base neutralization with trimethylamine to be converted into non - fishy non - volatile salts. The hydrophobic cavity of cyclodextrin in the porous cyclodextrin protects its phenolic hydroxyl groups from oxidation. Combined with the enzymatic hydrolysis of microbial - sourced fishy precursors by lysozyme and the promotion of component penetration by dynamic variable - temperature ultrasound, the generation of fishy smell in fish meat is blocked, and the residual fishy smell is significantly lower than that of traditional processes.

[0045] (2) In the present invention, resistant dextrin and stevia extract are used to replace white granulated sugar. Resistant dextrin can thicken and maintain the shape, replacing the adhesiveness of sugar. Through the composite gel composed of resistant dextrin and stevia extract, water loss is reduced during frying, the Maillard reaction between reducing sugar and amino acid during frying is blocked, the color of the food is improved. Camellia oil is used to carry the fat-soluble components of spices to penetrate into the fish meat, synergistically decompose the fishy smell protein with cooking wine, and through the vacuum tumbling process, ensure uniform penetration of the liquid mixture.

[0046] (3) Glutathione in yeast extract and lysozyme synergistically inhibit bacteria. L-ascorbyl palmitate, as a fat-soluble antioxidant, stably exists in camellia oil, inhibits the oxidation of fish meat while chelating metal ions, and maintains the color of fish meat. The process of the present invention has no additives such as sodium benzoate, meeting the healthy trend of low salt, sugar-free, and natural preservation. Description of the Drawings

[0047] Figure 1 It is the determination result of the fishy smell removal effect of Examples 1-3 and Comparative Examples 1-3 of the present invention.

[0048] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. Detailed Embodiments

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0050] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for illustrative purposes and do not limit the content of this application.

[0051] The experimental methods in the following embodiments are all conventional methods unless otherwise specified. The test materials used in the following embodiments are all obtained from commercial channels unless otherwise specified.

[0052] All comparative examples and embodiments of the present invention are filled and produced in tinplate cans.

[0053] Example 1

[0054] A preparation method of a low-salt and sugar-free aquatic food, comprising the following steps:

[0055] (1) Pretreatment: After removing the head, tail and internal organs of fresh hairtail, first rinse the surface mucus with 3% light brine by mass percentage, then soak it in 0.1% sodium bicarbonate ice water for 3 min, and finally treat it with an ultrasonic water washer at a frequency of 40 kHz for 2 min. After draining, cut it into 3-cm fish blocks;

[0056] (2) Deodorization treatment: Immerse the fish blocks in the compound deodorizing liquid at a material-liquid mass ratio of 1:3, perform dynamic temperature-changing ultrasonic treatment at 35 °C, and then perform rinsing and draining;

[0057] The compound deodorizing liquid is composed of the following components by mass percentage: 0.3% yeast extract, 0.1% porous cyclodextrin-pomegranate peel ellagic acid complex, 0.02% lysozyme, 0.01% L-ascorbic acid 6-palmitate, 3% ethanol, and the rest is pure water;

[0058] The porous cyclodextrin-pomegranate peel ellagic acid complex is obtained by dissolving porous cyclodextrin and pomegranate peel ellagic acid in a 30% volume fraction of ethanol solution at a mass ratio of 1:0.5, stirring at 40 °C for 4 h, and then freeze-drying;

[0059] (3) Pickling: Put the deodorized fish blocks and the pickling material into a vacuum tumbler at a mass ratio of 10:1;

[0060] The pickling material is composed of the following components by mass percentage: 5% resistant dextrin, 1.5% stevia extract, 0.8% low-sodium salt, 2% high-oleic acid camellia oil, 1% chicken powder, 3% oyster sauce, 2% cooking wine, 0.3% pepper powder, 0.5% compound spice, and the rest is pure water;

[0061] (4) Frying: Specifically includes the following steps:

[0062] Initial frying: Fry the pickled fish blocks in high-oleic acid rapeseed oil at 155 °C for 30 s;

[0063] Draining: Transfer the fish blocks after initial frying to a vibrating sieve with an amplitude of 3 mm and a frequency of 50 times / min for 60 s of draining;

[0064] Re-frying: Fry in oil at 180 °C for 60 s, and then treat with a centrifugal oil separator at 1200 r / min for 1 min;

[0065] (5) Canning: Pack the fried fish blocks and the sauce into a tinplate can at a weight ratio of 3:1;

[0066] (6) Exhausting and sealing: Exhaust the tinplate can by progressive heating, and then seal it;

[0067] (7) Sterilization and cooling: Place the canned product in a sterilization kettle for sterilization to obtain the low-salt and sugar-free aquatic food product.

[0068] The ultrasonic parameters of the dynamic variable-temperature ultrasonic treatment are as follows: dual-frequency alternation, main frequency 28 kHz, auxiliary frequency 68 kHz, and power density 300 W / m 2 , first heat up to 35 °C, keep warm for 5 min, then heat up to 42 °C, keep warm for 5 min, and finally cool down to 38 °C, keep warm for 10 min.

[0069] The working parameters of the vacuum tumbler are as follows: adopt the intermittent tumbling mode under a pressure of -0.08 MPa, rotate forward for 5 min, stand still for 5 min, rotate backward for 5 min, and the total duration is 45 min.

[0070] The compound spice is composed of rosemary powder, garlic powder, and clove extract in a mass ratio of 4:1.5:1.

[0071] The sauce is composed of the following components in parts by mass: 80 parts of softened water, 8 parts of glycyrrhizin, and 5 parts of vinegar.

[0072] During the exhaust process, heat up to 90 °C at a rate of 1 °C / min. After maintaining the center temperature of the tank ≥ 85 °C, evacuate to 0.04 Mpa.

[0073] The sterilization temperature is 115 °C and the sterilization time is 10 min. The cooling process is carried out in the following three stages:

[0074] Cool from 100 °C to 80 °C, cool down with water spray, and the duration is 4 min;

[0075] Cool from 80 °C to 50 °C, cool down with air, the wind speed is 3 m / s, and the duration is 6 min;

[0076] Cool from 50 °C to room temperature, stand still to cool down, and the duration is 20 min.

[0077] Example 2

[0078] A method for preparing a low-salt and sugar-free aquatic food, comprising the following steps:

[0079] (1) Pretreatment: After removing the head, tail, and internal organs of fresh hairtail, first rinse the surface mucus with 5% light brine by mass percentage, then soak it in 0.3% sodium bicarbonate ice water by mass percentage for 8 min, and finally treat it with an ultrasonic water washer at a frequency of 40 kHz for 5 min. After draining, cut it into 5-cm fish pieces;

[0080] (2) Deodorization treatment: Immerse the fish pieces in the compound deodorizing liquid according to the mass ratio of material to liquid of 1:5, carry out dynamic variable-temperature ultrasonic treatment at 45 °C, and then carry out rinsing and draining;

[0081] The compound deodorizing liquid is composed of the following components by mass percentage: 0.6% yeast extract, 0.3% porous cyclodextrin-pomegranate peel ellagic acid complex, 0.05% lysozyme, 0.03% L-ascorbic acid 6-palmitate, 8% ethanol, and the rest is pure water;

[0082] The porous cyclodextrin-pomegranate peel ellagic acid complex is obtained by dissolving porous cyclodextrin and pomegranate peel ellagic acid in an ethanol solution with a volume fraction of 30% at a mass ratio of 1:2, stirring at 40 °C for 6 h, and then freeze-drying;

[0083] (3) Pickling: Put the deodorized fish blocks and the pickling agent into a vacuum tumbler at a mass ratio of 15:1;

[0084] The pickling agent is composed of the following components by mass percentage: 8% resistant dextrin, 2.5% stevia extract, 1.5% low-sodium salt, 4% high-oleic acid camellia oil, 2% chicken powder, 5% oyster sauce, 3% cooking wine, 0.5% pepper powder, 1.2% compound spice, and the rest is pure water;

[0085] (4) Frying: Specifically includes the following steps:

[0086] Initial frying: Fry the pickled fish blocks in high-oleic acid rapeseed oil at 165 °C for 45 s;

[0087] Draining: Transfer the fish blocks after initial frying to a vibrating sieve with an amplitude of 5 mm and a frequency of 70 times / min for draining for 120 s;

[0088] Re-frying: Fry in oil at 183 °C for 90 s, and then treat with a centrifugal oil separator at 1500 r / min for 3 min;

[0089] (5) Canning: Put the fried fish blocks and the sauce into a tinplate can at a weight ratio of 4:1;

[0090] (6) Exhausting and sealing: Exhaust the tinplate can by progressive heating, and then seal it;

[0091] (7) Sterilizing and cooling: Put the canned product into a sterilization kettle for sterilization to obtain the low-salt and sugar-free aquatic food.

[0092] The ultrasonic parameters of the dynamic variable-temperature ultrasonic treatment are: dual-frequency alternation, main frequency 28 kHz, auxiliary frequency 68 kHz, power density 500 W / m 2 First, heat up to 35 °C, keep warm for 8 min, then heat up to 42 °C, keep warm for 8 min, and finally cool down to 38 °C, keep warm for 15 min.

[0093] The working parameters of the vacuum tumbler are: adopt the intermittent tumbling mode under a pressure of -0.1 MPa, tumble forward for 5 min, stand still for 5 min, tumble backward for 5 min, and the total duration is 60 min.

[0094] The compound spice is composed of rosemary powder, garlic powder, and clove extract in a mass ratio of 6:2:1.

[0095] The sauce is composed of the following components in parts by mass: 85 parts of softened water, 12 parts of stevioside, and 8 parts of vinegar.

[0096] During the exhaust process, the temperature is raised to 95°C at a rate of 2°C / min. After maintaining the central temperature of the tank ≥85°C, it is evacuated to 0.06 Mpa.

[0097] The sterilization temperature is 121°C and the sterilization time is 15 min. The cooling process is carried out in the following three stages:

[0098] Cool from 100°C to 80°C, cool down by water spraying, with a duration of 6 min;

[0099] Cool from 80°C to 50°C, cool down by air cooling, with a wind speed of 5 m / s and a duration of 10 min;

[0100] Cool from 50°C to room temperature, cool down by standing still, with a duration of 30 min.

[0101] Example 3

[0102] A method for preparing a low-salt and sugar-free aquatic food, comprising the following steps:

[0103] (1) Pretreatment: After removing the head, tail, and internal organs of fresh hairtail, first rinse the surface mucus with 4% brine by mass percentage, then soak it in 0.2% sodium bicarbonate ice water for 5 min, and finally treat it with an ultrasonic water washer at a frequency of 40 kHz for 3 min. After draining, cut it into 4-cm fish pieces.

[0104] (2) Deodorization treatment: Immerse the fish pieces in the compound deodorant liquid at a material-liquid mass ratio of 1:4, perform dynamic temperature-changing ultrasonic treatment at 40°C, and then rinse and drain.

[0105] The compound deodorant liquid is composed of the following components in mass percentage: 0.45% yeast extract, 0.2% porous cyclodextrin-pomegranate peel ellagic acid complex, 0.035% lysozyme, 0.02% L-ascorbic acid 6-palmitate, 5.5% ethanol, and the rest is pure water;

[0106] The porous cyclodextrin-pomegranate peel ellagic acid complex is obtained by dissolving porous cyclodextrin and pomegranate peel ellagic acid in a mass ratio of 1:1.25 in an ethanol solution with a volume fraction of 30%, stirring at 40°C for 5 h, and then freeze-drying.

[0107] (3) Marinating: Put the deodorized fish pieces and the marinating material into a vacuum tumbler at a mass ratio of 12.5:1;

[0108] The pickling agent is composed of the following components by mass percentage: 6.5% resistant dextrin, 2% stevia extract, 1.15% low-sodium salt, 3% high-oleic camellia oil, 1.5% chicken powder, 4% oyster sauce, 2.5% cooking wine, 0.4% pepper powder, 0.85% compound spice, and the rest is pure water;

[0109] (4) Frying: Specifically, it includes the following steps:

[0110] Initial frying: Place the pickled fish pieces in high-oil sauerkraut rapeseed oil at 160 °C and fry for 37.5 s;

[0111] Draining: Transfer the fish pieces after initial frying to a vibrating sieve with an amplitude of 4 mm and a frequency of 60 times / min for 90 s of draining;

[0112] Re-frying: Fry in oil at 181.5 °C for 75 s, and then process in a centrifugal oil separator at 1350 r / min for 2 min;

[0113] (5) Canning: Pack the fried fish pieces and the sauce into a tinplate can according to a weight ratio of 3.5:1;

[0114] (6) Exhausting and sealing: Exhaust the tinplate can by progressive heating, and then seal it;

[0115] (7) Sterilization and cooling: Place the canned product in a sterilization kettle for sterilization to obtain the low-salt and sugar-free aquatic food.

[0116] The ultrasonic parameters of the dynamic variable-temperature ultrasonic treatment are: dual-frequency alternation, main frequency 28 kHz, auxiliary frequency 68 kHz, power density 400 W / m 2 , first heat up to 35 °C, keep warm for 6.5 min, then heat up to 42 °C, keep warm for 6.5 min, and finally cool down to 38 °C, keep warm for 12.5 min.

[0117] The working parameters of the vacuum tumbler are: adopt the intermittent tumbling mode under a pressure of -0.09 MPa, rotate forward for 5 min, stand still for 5 min, rotate backward for 5 min, and the total duration is 52.5 min.

[0118] The compound spice is composed of rosemary powder: garlic powder: clove extract = 5:1.75:1 by mass ratio.

[0119] The sauce is composed of the following components by mass: 82.5 parts of softened water, 10 parts of monk fruit powder, and 6.5 parts of vinegar.

[0120] During the exhausting process, heat up to 92.5 °C at a rate of 1.5 °C / min, maintain the center temperature of the can ≥ 85 °C, and then evacuate to 0.05 Mpa.

[0121] The sterilization temperature is 118°C and the sterilization time is 12.5 min. The cooling process is carried out in three stages as follows:

[0122] Cool from 100°C to 80°C, cool down by water spraying for 5 min;

[0123] Cool from 80°C to 50°C, cool down by air cooling with a wind speed of 4 m / s for 8 min;

[0124] Cool from 50°C to room temperature, cool down by standing for 25 min.

[0125] Comparative Example 1

[0126] In this comparative example, a 1% sodium chloride solution by mass fraction was used to remove fishy smell, and the rest was the same as in Example 3.

[0127] Comparative Example 2

[0128] In this comparative example, a chemical method was used to remove fishy smell, that is, a mixed solution of 0.5% citric acid and 0.3% sodium metabisulfite by mass fraction was used as the fishy smell removing liquid, and the rest was the same as in Example 3.

[0129] Comparative Example 3

[0130] In this comparative example, the porous cyclodextrin-punicalagin complex was not prepared, but porous cyclodextrin and punicalagin were added separately, and the rest was the same as in Example 3.

[0131] Comparative Example 4

[0132] In this comparative example, resistant dextrin was not added during the pickling process, and the rest was the same as in Example 3.

[0133] Comparative Example 5

[0134] In this comparative example, stevia extract was not added during the pickling process, and the rest was the same as in Example 3.

[0135] Test Example 1

[0136] Determination of fishy smell removal effect

[0137] The trimethylamine residue in the hairtail after fishy smell removal treatment in Examples 1 - 3 and Comparative Examples 1 - 3 was detected by spectrophotometry, and the results are shown in Figure 1 .

[0138] According to the detection results of spectrophotometry, the trimethylamine residue in hairtail in Examples 1-3 was significantly lower than that in the comparative examples. In the examples, the porous cyclodextrin-pomegranate peel ellagic acid complex was used to reduce fishy smell through the mechanisms of physical adsorption and chemical neutralization. Combined with dynamic variable-temperature ultrasonic treatment, it accelerated the penetration of the deodorizing components into the deep layer of muscle, reducing the trimethylamine residue to the lowest level. Lysozyme decomposed the microbial-derived fishy smell precursors, further reducing the generation of fishy smell. In Comparative Example 1, only relying on the penetration of brine, it could not neutralize trimethylamine or adsorb volatile fishy smell substances. Although citric acid and sodium metabisulfite in Comparative Example 2 could remove fishy smell in the short term, they damaged the fish tissue structure and easily caused some fishy smell substances to remain. In Comparative Example 3, the adsorption efficiency of porous cyclodextrin and pomegranate peel ellagic acid alone was low, proving that the combination of porous cyclodextrin and pomegranate peel ellagic acid could play a better role in removing fishy smell.

[0139] Test Example 2

[0140] Detection of physical and chemical indexes

[0141] The physical and chemical indexes of the canned foods prepared in Examples 1-3 and Comparative Examples 1-5 were detected, and the results are shown in Table 1.

[0142] As can be seen from Table 1, Examples 1-3 were superior to Comparative Examples 1-5 in terms of health indexes, nutrient retention and texture properties, as follows:

[0143] In the examples, low-sodium salt and natural spices were used to replace the traditional high-salt formula, and the sodium content was significantly reduced;

[0144] The combined inhibition of lipid oxidation by high-oleic acid camellia oil (and L-ascorbic acid 6-palmitate) was carried out, so the peroxide value of the canned foods prepared in the examples was also lower. In Examples 4-5, due to the lack of the water-retaining effect of resistant dextrin or stevia extract, the water loss during frying exacerbated lipid oxidation;

[0145] Resistant dextrin and stevia extract formed a gel layer, reducing water evaporation and oil penetration during frying. Therefore, the water loss rate and oil absorption rate in the examples were lower than those in the comparative examples;

[0146] In the present invention, the pickling agent was evenly penetrated through the vacuum tumbling process. Combined with the thickening effect of resistant dextrin, the tenderness and elasticity of the fish meat were the best;

[0147] The present invention also reduced the destruction of thermosensitive fatty acids. In Examples 4-5, due to the lack of the water-retaining effect of resistant dextrin or stevia extract, the local high temperature during frying exacerbated the oxidation of DHA / EPA.

[0148] Table 1 Detection results of physical and chemical indexes of Examples 1-3 and Comparative Examples 1-5

[0149]

[0150]

[0151] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0152] The above description of the present invention and its embodiments is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual application is not limited thereto. In general, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design similar ways and embodiments to this technical solution without creative efforts, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a low-salt and sugar-free aquatic food, characterized in that: The following steps are involved: (1) Pretreatment: After removing the head, tail and internal organs of fresh aquatic raw materials, first wash the surface mucus with 3-5% by mass salt water, then soak in 0.1-0.3% by mass sodium bicarbonate ice water for 3-8 minutes, and finally treat with an ultrasonic water washing machine at a frequency of 40kHz for 2-5 minutes, drain and cut into 3-5cm fish pieces, the fresh aquatic raw materials include but are not limited to hairtail and yellow croaker; (2) Deodorization: immerse the fish pieces in a composite deodorization liquid at a feed-liquid mass ratio of 1:3-1:5, perform dynamic temperature-variable ultrasonic treatment at 35-45°C, and then rinse and drain; The composite deodorizing liquid is composed of the following components in percentage by mass: 0.3-0.6% yeast extract, 0.1-0.3% porous cyclodextrin-pomegranate peel ellagic acid complex, 0.02-0.05% lysozyme, 0.01-0.03% L-ascorbic acid 6-palmitate, 3-8% ethanol, and the rest is pure water; The porous cyclodextrin-pomegranate peel ellagic acid complex is obtained by dissolving porous cyclodextrin and pomegranate peel ellagic acid in a mass ratio of 1:0.5-2 in a 30% volume fraction ethanol solution, stirring at 40° C. for 4-6 hours, and then freeze-drying. (3) Pickling: put the deodorized fish pieces and the pickling material into a vacuum tumbling machine at a mass ratio of 10:1-15:1; The pickling material is composed of the following components in percentage by mass: 5-8% resistant dextrin, 1.5-2.5% stevia extract, 0.8-1.5% low sodium salt, 2-4% high oleic camellia oil, 1-2% chicken powder, 3-5% oyster sauce, 2-3% cooking wine, 0.3-0.5% pepper powder, 0.5-1.2% compound spices, and the rest is pure water; (4) Frying: specifically comprising the following steps: Initial frying: deep fry the marinated fish pieces in high oleic rapeseed oil at 155-165℃ for 30-45s; Drain the oil: transfer the fish pieces after initial frying to a vibrating screen with an amplitude of 3-5 mm and a frequency of 50-70 times / min to drain the oil for 60-120 seconds; Re-frying: fry in oil at 180-183℃ for 60-90s, then process in a centrifugal de-oiling machine at 1200-1500r / min for 1-3min; (5) Filling: Put the fried fish pieces and sauce into tinplate cans, glass bottles or high-temperature sterilization bags at a weight ratio of 3:1-4:1; (6) Exhaust and seal: exhaust the product after filling and then seal it; (7) Sterilization and cooling: Place the filled product into a sterilizer for sterilization and then cool it.

2. The method for preparing the low-salt and sugar-free aquatic food according to claim 1, characterized in that: The ultrasonic parameters of the dynamic temperature-variable ultrasonic treatment are: dual-frequency alternation, main frequency 28kHz, auxiliary frequency 68kH, power density 300-500W / m 2 , first raise the temperature to 35℃, keep it warm for 5-8min, then raise the temperature to 42℃, keep it warm for 5-8min, and finally cool down to 38℃, keep it warm for 10-15min.

3. The method for preparing the low-salt and sugar-free aquatic food according to claim 2, characterized in that: The working parameters of the vacuum tumbling machine are: intermittent tumbling mode under a pressure of -0.08 to -0.1 MPa, forward rotation for 5 minutes, rest for 5 minutes, reverse rotation for 5 minutes, and a total time of 45-60 minutes.

4. The method for preparing the low-salt and sugar-free aquatic food according to claim 3, characterized in that: The composite spice is composed according to the mass ratio of rosemary powder: garlic powder: clove extract = 4-6: 1.5-2:

1.

5. The method for preparing the low-salt and sugar-free aquatic food according to claim 4, characterized in that: The sauce is composed of the following components in parts by mass: 80-85 parts of softened water, 8-12 parts of sugar-free natural sweetener and 5-8 parts of vinegar; the sugar-free natural sweetener is selected from one or more of monk fruit powder, glycyrrhizin, stevioside, mannitol and hesperidin.

6. The method for preparing the low-salt and sugar-free aquatic food according to claim 1, characterized in that: When a tinplate can is used in the filling step, the tinplate can is vented by progressive heat and then sealed; The exhaust process is heated to 90-95°C at a rate of 1-2°C / min, and after the center temperature of the tank is maintained at ≥85°C, the vacuum is drawn to 0.04-0.06Mpa; The sterilization temperature is 115-121°C and the sterilization time is 10-15min; The cooling process is performed in three stages: Cool from 100℃ to 80℃, cool with water for 4-6min; Cool from 80℃ to 50℃, air cooling, wind speed 3-5m / s, duration 6-10min; Cool from 50℃ to room temperature and let it stand to cool for 20-30 minutes.

7. The method for preparing the low-salt and sugar-free aquatic food according to claim 1, characterized in that: When the filling step adopts glass bottle filling, the exhaust and sealing step adopts vacuum pumping to exhaust the glass bottle and then seals it; The sterilization temperature is 105-110°C, the sterilization time is 8-12min, and the pressure in the sterilization kettle is 0.12-0.15MPa; The cooling step adopts segmented water cooling, cooling from 70°C to 40°C, and then to 25°C in sequence, with a total cooling time of 20-25 minutes, and applying a back pressure of 0.1-0.12 MPa.

8. The method for preparing the low-salt and sugar-free aquatic food according to claim 1, characterized in that: When the filling step adopts a high-temperature sterilization bag for filling, the exhaust and sealing step adopts vacuum heat sealing to exhaust and seal the high-temperature sterilization bag, the sterilization temperature is 135°C, the sterilization time is 3-5min, and the pressure in the sterilization autoclave is 0.25-0.3MPa; The cooling step adopts a combination of pressurized air cooling and cold water spraying, the cooling time is 8-10 minutes, and the pressure is reduced in a step-by-step manner during the cooling stage, reducing by 0.05 MPa every 2 minutes.

9. A low-salt and sugar-free aquatic food, characterized by: The invention is prepared by the preparation method according to any one of claims 1 to 8.

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