Frozen raw pickled shrimp paste with ice cream-like taste and preparation method thereof

Abstract

The present invention provides a frozen raw pickled shrimp paste with an ice cream-like taste and a preparation method thereof, which specifically includes the preparation of hot-pressed sturgeon cartilage collagen, the preparation of a nano-emulsified solution, the pickling of raw materials, the pickling of shrimp paste and the preparation of frozen raw pickled shrimp paste. The present invention prepares sturgeon cartilage collagen by high-temperature and high-pressure liquefaction technology, combines nano-emulsification and ultra-high pressure cold sterilization treatment technology, and develops a frozen raw pickled shrimp paste that can be eaten raw and has an ice cream-like taste, thereby improving the taste and quality of the shrimp paste.

Description

Technical Field

[0001] The invention belongs to the technical field of aquatic product processing, and particularly relates to frozen raw pickled shrimp paste with an ice cream-like taste and a preparation method thereof. Background Art

[0002] Raw pickled seafood is a traditional food with a long history and unique culture. It not only attracts countless diners with its unique flavor, but also becomes a symbol of regional culture and a treasure of food exploration over the long years. Raw pickled seafood is not just a dish, but also a heritage and embodiment of culture. It represents people's ultimate pursuit of food and deep respect for tradition. Whenever there is a festival celebration or family reunion, a plate of raw pickled seafood with good color, aroma and taste becomes an indispensable part of the table, carrying people's yearning for a better life and good wishes for the future.

[0003] The preparation and consumption of raw pickled shrimp only appear in daily diet. There is no precedent for raw pickled shrimp paste that can be eaten raw, either in the current market or in previous papers and patents. This is mainly because, in the process of making shrimp paste, mincing or chopping the shrimp meat will release a large amount of water, making the shrimp paste have a high moisture content. High moisture content is not conducive to the penetration of salt and the uniform distribution of marinade during the pickling process, thus affecting the pickling effect. At the same time, the tissue structure of shrimp paste is relatively loose and lacks a complete muscle fiber structure. This loose structure makes it difficult for the marinade to form an effective pickling environment inside the minced meat, which easily leads to uneven pickling and affects the flavor and taste of the product. In addition, raw pickled foods usually require a long pickling time to ensure that the marinade fully penetrates into the ingredients. However, for shrimp paste, too long a pickling time may cause excessive water loss, making the shrimp paste dry and hard, while too short a pickling time will not allow the marinade to fully work, affecting the pickling effect. Finally, raw pickled foods are not heated during the production process and are easily contaminated by microorganisms. Moreover, due to the loose structure and high moisture content of shrimp paste, microorganisms are more likely to reproduce and grow in it.

[0004] At present, the frozen food market has broad prospects worldwide. With the increasing demand of consumers for healthy and convenient foods, frozen foods have significant advantages in preserving nutrition and convenient consumption. At the same time, in the food industry, the pursuit of a delicate and soft taste similar to ice cream has become a trend. Many products adjust their formulas and production processes to achieve this unique taste effect. This taste not only enhances the attractiveness of food, but also brings consumers a new eating experience. Therefore, the development of frozen raw marinated shrimp paste that can be eaten raw and has an ice cream taste is an innovative attempt in line with market development trends. However, this also requires that the shrimp paste has a foam structure that emulsifies proteins, oils and other exogenous substances to form a stable bubble coexistence, so as to avoid losing the dense and delicate taste similar to ice cream during the freezing process. On the one hand, the size of ice crystals determines the texture structure of shrimp paste. The smaller the ice crystals, the better the texture of shrimp paste, the more delicate the taste, and the absence of ice residue. On the other hand, the formation, growth and recrystallization of ice crystals will cause the protein in shrimp paste to be easily frozen and denatured, thereby affecting the color, flavor, nutritional value and taste of shrimp paste gel.

[0005] Combining traditional raw pickling technology with the modern taste of ice cream is a cross-border innovation attempt. Traditional raw pickled seafood is well-loved for its unique flavor, while ice cream is famous for its delicate and soft taste. Combining the two can not only retain the freshness of raw pickled seafood, but also give it a new taste experience. Through specific processes and formulas, the shrimp paste has a delicate and soft taste similar to ice cream in a frozen state, which is very rare in seafood products. This taste innovation can attract consumers who pursue novel experiences and meet their diversified needs for food. It can be eaten directly as an appetizer, or as a substitute or ingredient for ice cream, and combined with other ingredients to create more delicious combinations. Secondly, as people's pursuit of health and food continues to improve, this raw pickled shrimp paste that combines tradition and modernity and has a unique taste is expected to occupy a place in the market. It is not only suitable for young people's pursuit of fresh and exciting consumer psychology, but also for those consumers who pay attention to healthy eating. Summary of the invention

[0006] Technical problem to be solved: In view of the above technical problems, the purpose of the present invention is to provide a frozen raw pickled shrimp paste with an ice cream-like taste and a preparation method thereof, which specifically includes the preparation of hot-pressed sturgeon cartilage collagen, the preparation of nano-emulsified solution, the pickling of raw materials, the pickling of shrimp paste and the preparation of frozen raw pickled shrimp paste.

[0007] Technical solution: A method for preparing frozen raw marinated shrimp paste with an ice cream-like taste, comprising the following steps:

[0008] S1. Preparation of hot-pressed sturgeon cartilage collagen: cut the sturgeon cartilage into small pieces, soak and stir in 0.1mol / L NaHCO3 solution for 0.5-1h, and wash until neutral; soak the washed sturgeon cartilage in 0.1mol / L citric acid solution and stir for 0.5-1h, and wash until neutral; then mix the sturgeon cartilage with distilled water, extract at 115-121°C, 0.07-0.12Mpa for 30-50min, centrifuge, take the supernatant, freeze-dry, and obtain hot-pressed sturgeon cartilage collagen powder, which is refrigerated for later use;

[0009] S2. Preparation of nanoemulsified solution: adding hot-pressed sturgeon cartilage collagen powder to cold water at 4°C, stirring until completely dissolved to obtain a collagen solution, adding egg white, stirring for 30 min until uniformly mixed, obtaining a hot-pressed sturgeon cartilage collagen-egg white mixed solution as the aqueous phase, corn oil as the oil phase, mixing, and adding 2-3% of soft white sugar by mass of the mixed solution, emulsifying, and homogenizing into a crude emulsion; ultrasonicating the crude emulsion under ice-water bath conditions, filtering, and performing high-pressure homogenization treatment at 25 MPa and 20°C. The homogenized emulsion is placed in a refrigerated aging at 4°C for 10-15 h to obtain a nanoemulsified solution;

[0010] S3. Marinating of raw materials: Select fresh shrimps, add seasonings, stir evenly, and marinate at 4°C for 10 hours to obtain marinated shrimps;

[0011] S4. Marinating shrimp paste: add salt to the marinated shrimp, chop and mix until shrimp paste, then add nano-emulsified solution and raw marinade, transfer to an ice cream machine, stir thoroughly at 2800-3000r / min, then add 3% cooked starch, and continue stirring until smooth and uniform; S5. Preparation of frozen raw marinated shrimp paste: take out the shrimp paste when the temperature is -8℃~-10℃, can and package it, and place it in a cold water treatment warehouse for ultra-high pressure treatment, sterilization, quick freezing, and frozen storage to obtain frozen raw marinated shrimp paste.

[0012] Furthermore, in step S1, the solid-liquid ratio of sturgeon cartilage to NaHCO3 solution is 1:(5-10); the solid-liquid ratio of sturgeon cartilage to citric acid solution is 1:(5-10); and the solid-liquid ratio of sturgeon cartilage to distilled water is 1:(4-5).

[0013] Furthermore, in step S1, the centrifugal speed is 8000-10000 r / min, and the centrifugal time is 20-30 min.

[0014] Furthermore, in step S2, the amount of hot-pressed sturgeon cartilage collagen powder added is 50-55wt%; the mass ratio of the egg white to the collagen solution is 1:(5-5.5); and the volume ratio of the oil phase to the water phase is (2-2.5):(7.5-8).

[0015] Furthermore, in step S2, the homogenization speed is 16000 r / min, and the homogenization time is 2-3 min; the ultrasonic power is 300-500 W, and the ultrasonic time is 2-3 min.

[0016] Furthermore, in step S3, the seasoning is 5-10g salt, 3-5g white sugar, 5-10mL cooking wine, 5-10mL light soy sauce, 5-10mL balsamic vinegar, 1-3mL dark soy sauce, 10-20g garlic, 10-15g ginger, 5-10g chili and 10-20g coriander per 100g shrimp.

[0017] Furthermore, in step S4, the salt accounts for 1-2wt% of the pickled shrimp; the nano-emulsified solution accounts for 30-50vt% of the pickled shrimp; and the raw marinade accounts for 10-15vt% of the pickled shrimp.

[0018] Furthermore, the ultrahigh pressure treatment conditions in step S5 are as follows: the pressure is set to 600 MPa, the pressure is increased for 7 minutes, the pressure is maintained for 5 minutes, the pressure is reduced for 1 minute, and the temperature is lower than 15° C. throughout the process.

[0019] Beneficial effects:

[0020] 1. The interaction between egg white and hot-pressed sturgeon cartilage collagen (stabilizer) in the present invention can increase the viscosity of shrimp paste slurry, reduce the fluidity of water near ice crystals, and make ice crystals evenly distributed and small in size, thereby improving the dense taste of frozen raw marinated shrimp paste.

[0021] 2. In order to simulate the dense mouthfeel of ice cream made of frozen marinated shrimp paste, the present invention combines the emulsification, homogenization, aging, refrigeration and freezing stirring in the production steps, emulsifies and combines egg white with corn oil, generates bubbles and ice crystals during the freezing stirring process, and forms a multiphase system of fat globules, bubbles, ice crystals and concentrated clear liquid phase (including sugar, polysaccharide stabilizer, protein, etc.); wherein, the fat network structure formed by corn oil during the freezing process can stabilize the air and maintain the shape, the high fat content will reduce the icy feeling, and the partial aggregation of fat globules will also promote the formation of small ice crystal size. During the whipping process during freezing, the fat globules crystallize and aggregate to form a network that supports bubbles. The bubbles can act as insulators, reduce temperature fluctuations, prevent water from migrating toward the ice crystals, and inhibit the growth of ice crystals.

[0022] 3. The hot-pressed sturgeon cartilage collagen nanoemulsified solution added to the frozen raw marinated shrimp paste of the present invention can be specifically adsorbed with ice crystals, and electrostatic interaction plays a major role in the adsorption and binding process with the basal surface, edge surface and secondary edge surface of the ice crystals, so that the ice crystals can only grow further between the adsorbed antifreeze protein molecules, thereby bending the ice surface, increasing the surface curvature and causing the freezing point to drop. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A schematic diagram of the route;

[0024] Figure 2 Comparison of residual catalase activity among blank group, commercial antifreeze group and nanoemulsified solution group;

[0025] Figure 3 This is a comparison chart of DPPH free radical scavenging activity between vitamin C and nanoemulsified solution group;

[0026] Figure 4 This is a comparison chart of the difference in emulsion stability index among the blank group, commercial antifreeze group and nanoemulsified solution group;

[0027] Figure 5 The difference diagram of sensory evaluation of frozen raw marinated shrimp paste among commercial ice cream group, blank group, commercial antifreeze group, nanoemulsion solution group 30%, nanoemulsion solution group 40% and nanoemulsion solution group 50%;

[0028] Figure 6 The difference diagram of texture characteristics among commercial ice cream group, blank group, commercial antifreeze group, nanoemulsion solution group 30%, nanoemulsion solution group 40% and nanoemulsion solution group 50%;

[0029] Figure 7 The scanning electron microscopy difference images of the commercial ice cream group, the blank group, the commercial antifreeze group, the nanoemulsion solution group 30%, the nanoemulsion solution group 40%, and the nanoemulsion solution group 50% are shown;

[0030] Figure 8 This is a graph showing the difference in glass transition temperatures of the commercial ice cream group, blank group, BSA group, commercial antifreeze group, nanoemulsion solution group 30%, nanoemulsion solution group 40%, and nanoemulsion solution group 50%. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are explanations of the present invention and the present invention is not limited to the following embodiments:

[0032] Example 1

[0033] A method for preparing frozen raw pickled shrimp paste with an ice cream-like taste comprises the following steps:

[0034] S1. Preparation of hot-pressed sturgeon cartilage collagen: Sturgeon cartilage was cut into pieces with a chopper at room temperature with a volume of about 1 cm 3The washed sturgeon cartilage was soaked in 0.1mol / L NaHCO3 solution at a solid-liquid ratio of 1:5 and stirred for 0.5h to wash until neutral; the washed sturgeon cartilage was soaked in 0.1mol / L citric acid solution at a solid-liquid ratio of 1:5 and stirred for 0.5h to wash until neutral; the sturgeon cartilage was mixed with distilled water at a ratio of 1:4, extracted at 115°C and 0.07Mpa for 30min, centrifuged at 8000r / min for 20min, the supernatant was taken, freeze-dried to obtain hot-pressed sturgeon cartilage collagen powder, and refrigerated for later use;

[0035] S2. Preparation of nanoemulsified solution: at 4°C, add 50 wt.% of hot-pressed sturgeon cartilage collagen powder to cold water, stir until completely dissolved to obtain a collagen solution, add egg white (the mass ratio of egg white to collagen solution is 1:5), stir for 30 min until uniformly mixed, obtain a hot-pressed sturgeon cartilage collagen-egg white mixed solution as the aqueous phase, corn oil as the oil phase, mix according to an oil-water ratio of 2:8, add 3% of the mass of the mixed solution of soft white sugar, emulsify, homogenize at 16000 r / min for 2 min, and prepare a crude emulsion; ultrasonicate the crude emulsion for 2 min (ultrasonic power 300 W) under ice-water bath conditions to obtain a nanoemulsified solution, filter, and perform high-pressure homogenization at 25 MPa and 20°C. The homogenized emulsion is placed in a refrigerated aging at 4°C for 10 h;

[0036] S3. Marinating of raw materials: Select fresh shrimps for use, add about 5g salt, 5g sugar, 5mL cooking wine, 10mL light soy sauce, 10mL balsamic vinegar, 1mL dark soy sauce, 10g garlic, 10g ginger, 5g chili, and 10g coriander for use per 100g shrimps, add the seasoning to the processed shrimps according to the formula ratio, stir evenly, marinate at 4°C for 10h, and obtain marinated shrimps and raw marinade;

[0037] S4. Marinated shrimp paste: add 1.5wt.% salt to the marinated shrimp, chop and mix until the shrimp paste is complete, add 30vt.% nanoemulsified solution and 10vt.% raw marinade to an ice cream machine, stir at 2800r / min, add 3% cooked starch, and continue stirring until smooth and uniform;

[0038] S5. Preparation of frozen raw pickled shrimp paste: Take out the shrimp paste when the temperature is -8°C to -10°C, can and package it, and place it in a cold water treatment chamber for ultra-high pressure treatment. The pressure is set to 600MPa, increase the pressure for 7 minutes, maintain the pressure for 5 minutes, and reduce the pressure for 1 minute. The temperature is lower than 15°C throughout the process. Sterilize it, freeze it using air blast quick freezing technology, and store it in a frozen state to obtain frozen raw pickled shrimp paste (nanoemulsified solution group 30%).

[0039] Example 2

[0040] A method for preparing frozen raw pickled shrimp paste with an ice cream-like taste comprises the following steps:

[0041] S1. Preparation of hot-pressed sturgeon cartilage collagen: Sturgeon cartilage was cut into pieces with a chopper at room temperature with a volume of about 1 cm 3 The washed sturgeon cartilage was soaked in 0.1mol / L NaHCO3 solution at a solid-liquid ratio of 1:5 and stirred for 0.5h to wash until neutral; the washed sturgeon cartilage was soaked in 0.1mol / L citric acid solution at a solid-liquid ratio of 1:5 and stirred for 0.5h to wash until neutral; the sturgeon cartilage was mixed with distilled water at a ratio of 1:4, extracted at 115°C and 0.07Mpa for 30min, centrifuged at 8000r / min for 20min, the supernatant was taken, freeze-dried to obtain hot-pressed sturgeon cartilage collagen powder, and refrigerated for later use;

[0042] S2. Preparation of nanoemulsified solution: at 4°C, add 50 wt.% of hot-pressed sturgeon cartilage collagen powder to cold water, stir until completely dissolved to obtain a collagen solution, add egg white (the mass ratio of egg white to collagen solution is 1:5), stir for 30 min until uniformly mixed, obtain a hot-pressed sturgeon cartilage collagen-egg white mixed solution as the aqueous phase, corn oil as the oil phase, mix according to an oil-water ratio of 2:8, add 3% of the mass of the mixed solution of soft white sugar, emulsify, homogenize at 16000 r / min for 2 min, and prepare a crude emulsion; ultrasonicate the crude emulsion for 2 min (ultrasonic power 300 W) under ice-water bath conditions to obtain a nanoemulsified solution, filter, and perform high-pressure homogenization at 25 MPa and 20°C. The homogenized emulsion is placed in a refrigerated aging at 4°C for 10 h;

[0043] S3. Marinating of raw materials: Select fresh shrimps for use, add about 5g salt, 5g sugar, 5mL cooking wine, 10mL light soy sauce, 10mL balsamic vinegar, 1mL dark soy sauce, 10g garlic, 10g ginger, 5g chili, and 10g coriander for use per 100g shrimps, add the seasoning to the processed shrimps according to the formula ratio, stir evenly, marinate at 4°C for 10h, and obtain marinated shrimps and raw marinade;

[0044] S4. Marinated shrimp paste: add 1.5wt.% salt to the marinated shrimp, chop and mix until the shrimp paste is complete, add 40vt.% nanoemulsified solution and 10vt.% raw marinade to an ice cream machine, stir at 2800r / min, add 3% cooked starch, and continue stirring until smooth and uniform;

[0045] S5. Preparation of frozen raw pickled shrimp paste: Take out the shrimp paste when the temperature is -8°C to -10°C, can and package it, and place it in a cold water treatment chamber for ultra-high pressure treatment. The pressure is set to 600MPa, increase the pressure for 7 minutes, maintain the pressure for 5 minutes, and reduce the pressure for 1 minute. The temperature is lower than 15°C throughout the process. Sterilize it, freeze it using air blast quick freezing technology, and store it in a frozen state to obtain frozen raw pickled shrimp paste (40% of nanoemulsified solution group).

[0046] Example 3

[0047] A method for preparing frozen raw pickled shrimp paste with an ice cream-like taste comprises the following steps:

[0048] S1. Preparation of hot-pressed sturgeon cartilage collagen: Sturgeon cartilage was cut into pieces with a chopper at room temperature with a volume of about 1 cm 3 The washed sturgeon cartilage was soaked in 0.1mol / L NaHCO3 solution at a solid-liquid ratio of 1:5 and stirred for 0.5h to wash until neutral; the washed sturgeon cartilage was soaked in 0.1mol / L citric acid solution at a solid-liquid ratio of 1:5 and stirred for 0.5h to wash until neutral; the sturgeon cartilage was mixed with distilled water at a ratio of 1:4, extracted at 115°C and 0.07Mpa for 30min, centrifuged at 8000r / min for 20min, the supernatant was taken, freeze-dried to obtain hot-pressed sturgeon cartilage collagen powder, and refrigerated for later use;

[0049] S2. Preparation of nanoemulsified solution: at 4°C, add 50 wt.% of hot-pressed sturgeon cartilage collagen powder to cold water, stir until completely dissolved to obtain a collagen solution, add egg white (the mass ratio of egg white to collagen solution is 1:5), stir for 30 min until uniformly mixed, obtain a hot-pressed sturgeon cartilage collagen-egg white mixed solution as the aqueous phase, corn oil as the oil phase, mix according to an oil-water ratio of 2:8, add 3% of the mass of the mixed solution of soft white sugar, emulsify, homogenize at 16000 r / min for 2 min, and prepare a crude emulsion; ultrasonicate the crude emulsion for 2 min (ultrasonic power 300 W) under ice-water bath conditions to obtain a nanoemulsified solution, filter, and perform high-pressure homogenization at 25 MPa and 20°C. The homogenized emulsion is placed in a refrigerated aging at 4°C for 10 h;

[0050] S3. Marinating of raw materials: Select fresh shrimps for use, add about 5g salt, 5g sugar, 5mL cooking wine, 10mL light soy sauce, 10mL balsamic vinegar, 1mL dark soy sauce, 10g garlic, 10g ginger, 5g chili, and 10g coriander for use per 100g shrimps, add the seasoning to the processed shrimps according to the formula ratio, stir evenly, marinate at 4°C for 10h, and obtain marinated shrimps and raw marinade;

[0051] S4. Marinated shrimp paste: add 1.5wt.% salt to the marinated shrimp, chop and mix until the shrimp paste is formed, add 50vt.% nanoemulsified solution of shrimp mass and 10vt.% raw marinade to an ice cream machine, stir thoroughly at 2800r / min, add 3% cooked starch, and continue stirring until smooth and uniform;

[0052] S5. Preparation of frozen raw pickled shrimp paste: Take out the shrimp paste when the temperature is -8°C to -10°C, can and package it, and place it in a cold water treatment chamber for ultra-high pressure treatment. The pressure is set to 600MPa, increase the pressure for 7 minutes, maintain the pressure for 5 minutes, and reduce the pressure for 1 minute. The temperature is lower than 15°C throughout the process. Sterilize it, freeze it using air blast quick freezing technology, and store it in a frozen state to obtain frozen raw pickled shrimp paste (nano-emulsified solution group 50%).

[0053] Performance Test:

[0054] (i) Pure water was used as the blank group, an aqueous solution containing 2% sucrose and 2% sorbitol was used as the commercial antifreeze group, and the nanoemulsified solution prepared in Example 2 was used as the nanoemulsified solution group.

[0055] 1. Thermal hysteresis activity

[0056] Take 5μL of sample solution and seal it in a crucible. Place the sealed crucible in a DSC device to measure the thermal hysteresis activity of the sample. The initial temperature is set to 20℃, and the temperature is lowered to -20℃ at a rate of 5℃ / min and maintained for 2min; then the temperature is raised to 20℃ at the same rate and maintained for 2min to obtain the melting curve of the hydrolyzate. Then the temperature is lowered to -20℃ at the same rate again and maintained for 2min, and then the temperature is raised at a rate of 1℃ / min until the solution is partially molten. The temperature at this moment is called the retention temperature. Maintain it for 2min, and finally raise the temperature to 20℃ at a rate of 1℃ / min. The thermal hysteresis activity is calculated according to the formula:

[0057] THA=T h -T0

[0058] Where THA is thermal hysteresis activity; T h is the retention temperature, ℃; T0 is the initial crystallization temperature, ℃.

[0059] Table 1 Differences in thermal hysteresis activity of emulsions

[0060]

[0061]

[0062] Thermal hysteresis activity refers to the ability of a substance to lower the freezing point of a solution without affecting its melting point, and the difference between the freezing point and the melting point is the magnitude of the thermal hysteresis activity. Substances with thermal hysteresis activity can effectively inhibit the growth of ice crystals. The greater the thermal hysteresis activity, the more significant the effect. Therefore, thermal hysteresis activity can be used to determine the strength of the antifreeze activity of the nanoemulsified solution. From the results in Table 1, it can be seen that compared with the blank group samples, the nanoemulsified solution has a higher thermal hysteresis activity (THA) and a lower ice crystal content (Φ), indicating that the nanoemulsified solution has a higher antifreeze activity. Applying the nanoemulsified solution to shrimp slippery foods with a subsequent ice cream taste can effectively inhibit the growth and melting of ice crystals.

[0063] 2. Antifreeze activity

[0064] Dilute the catalase solution with pH7.0, 0.05mol / L PBS buffer, mix equal amounts of 0.2mg / mL catalase solution and 0.1% (w / v) solution to be tested, and mix equal amounts of 0.2mg / mL catalase dilution and 0.05mol / L PBS buffer in the control group to obtain two groups of 0.1mg / mL catalase mixed solutions to be tested, and measure the initial enzyme activity of catalase respectively. Put it in the refrigerator for 3h, take it out and thaw it in a water bath at 25℃, put it in the refrigerator for 3h and thaw it in a water bath, freeze it for 3h, and then thaw it in a water bath, freeze it repeatedly for 3 times, and measure the residual enzyme activity of catalase.

[0065] Catalase activity determination: adjust the initial concentration of hydrogen peroxide to an absorbance of 0.58 to 0.54 at 240 nm, use a micropipette to take 2.90 mL of hydrogen peroxide solution of appropriate concentration into a quartz cuvette, add 0.1 mL of the 0.1 mg / mL catalase mixture to be tested, use 0.05 mol / L PBS buffer as a reference, measure the absorbance at 240 nm, perform three parallel experiments, and record the time (t) required for the absorbance value to drop from 0.45 to 0.40. The calculation formula is as follows:

[0066] Catalase activity (U / mg) = (3.45*dilution factor)*t / 0.1

[0067] Freezing has a great influence on the quality of shrimp paste. By measuring the residual activity of catalase after freeze-thaw treatment, the antifreeze activity of the nanoemulsified solution can be obtained ( Figure 2 ). Compared with the blank group, the commercial antifreeze and nanoemulsion solution have good antifreeze activity. The nanoemulsion solution contains collagen products with hydrophilic groups (hydroxyl, carboxyl and amino substituents) on the side chains, which have strong inhibitory activity on ice recrystallization, low ice growth rate and small ice crystal size.

[0068] 3.DPPH free radical scavenging activity

[0069] The 1,1-diphenyl-2-pyridine (DPPH) free radical scavenging activity of vitamin C and nanoemulsified solution was determined using a kit.

[0070] from Figure 3 It can be seen that the antioxidant activity of the nanoemulsified solution is equivalent to that of vitamin C. Free radicals (-OH) will appear during the freezing process of shrimp paste. -OH is extremely unstable and can react with protein during the freezing process of aquatic products to destroy the original structure of the protein, causing changes in the properties of the protein, thereby reducing the quality of the aquatic products. The nanoemulsified solution can provide electrons to convert -OH into a more stable group, reduce the occurrence of oxidation reactions, inhibit the damage of oxidation to fat and protein during frozen storage, and maintain the taste and quality of shrimp paste.

[0071] (ii) The emulsion prepared in Example 2 without adding hot-pressed sturgeon cartilage collagen was used as the blank group, the aqueous solution containing 2% sucrose and 2% sorbitol was used as the commercial antifreeze group, and the nanoemulsified solution prepared in Example 2 was used as the nanoemulsified solution group.

[0072] 1. Emulsion particle size

[0073] The fresh and refrigerated aged nanoemulsified solutions prepared in proportion were dispersed in water, and the particle size distribution of the ice cream emulsion was measured using a laser particle size analyzer. The measurement results were expressed in D [4,3] Indicates that the calculation formula of the discrete degree PCD is as follows:

[0074] PCD=[D [4,3] (Emulsion after refrigeration)-D [4,3] (Fresh lotion)] / [D [4,3] (Lotion after refrigeration)

[0075] Table 2 Difference in emulsion particle size

[0076]

[0077] The emulsion system of ice cream is required to be stable under static conditions before production, and the fat globules will become unstable and partially aggregate during low-temperature whipping, thereby forming a stable network structure. As can be seen from the results in Table 2, the D [4,3] The D of the fresh emulsion in the blank group was the smallest. [4,3] The maximum value indicates that the emulsion stability is relatively poor. The nanoemulsified solution is easier to combine with egg white protein and oil during the homogenization process to maintain the stability of the emulsion. Based on this property, the nanoemulsified solution is applied to the raw marinated shrimp paste with the taste of ice cream to obtain shrimp paste with a denser and more delicate taste.

[0078] 2. Emulsion viscosity

[0079] The viscosity of the emulsion aged at 4°C was measured using a DV2T viscometer, using a rotor RV3 at a speed of 100 r / min.

[0080] Table 3 Difference in emulsion viscosity

[0081]

[0082] Increasing the viscosity of the emulsion can prevent the growth and recrystallization of ice crystals, thereby reducing its rough tongue feeling, making the finished product tissue lubricated, with good water absorption and not easy to melt. As shown in Table 3, the viscosity of the blank group is lower than that of the commercial antifreeze group and the nanoemulsion solution group, and the emulsion viscosity of the nanoemulsion solution is the highest. There is no significant difference in the viscosity of the emulsions after cold storage aging between the commercial antifreeze group and the nanoemulsion solution group, and the blank group is the lowest. Emulsions with higher viscosity can maintain a better shape during subsequent processing, slow down their melting rate, and increase the swelling rate, making the shrimp paste taste smoother. Nanoemulsion solution has strong water absorption and water retention, and when added to the emulsion, it increases its viscosity. In shrimp paste, stabilizers can gradually combine with water, connect with a large number of water molecules through hydrogen bonds, form a three-dimensional network structure, limit the fluidity of the remaining water phase, and make the emulsion produce a certain viscosity and spatial barriers to prevent the diffusion of water, thereby reducing the dissolution rate and the crystallization rate, thereby inhibiting the growth of ice crystals.

[0083] 3. Emulsion stability

[0084] The weighed liquid was diluted with distilled water to an appropriate multiple, centrifuged (4°C, 3500 rpm, 15 min), and the absorbance before and after centrifugation was measured, with the wavelength set at 785 nm. The stability index R was calculated according to the formula:

[0085] Stability index (R) = A 12 / A 11

[0086] Where: A 11 is the absorbance before centrifugation, A 12 Absorbance after centrifugation

[0087] from Figure 4It can be seen that the R value (stability index) of the blank group is 0.513, the R value (stability index) of the commercial antifreeze group is 0.742, and the R value (stability index) of the nanoemulsified solution is the largest, which is 0.876. Comparing the R value with 1, generally speaking, the closer the R value is to 1, the better and more stable the emulsion is; the greater the deviation from 1, the more it means that the internal structure of the protein molecules in the emulsion has changed, so that the original internal hydrophobic groups are exposed to the outside, the hydrophobic force is enhanced, or the emulsifier structure has been damaged to a certain extent, and a small part of the surfactants have aggregated, which reduces the solubility of the emulsion and the emulsification stability.

[0088] (III) The commercial ice cream group was composed of frozen ice cream purchased from the market; the blank group was composed of frozen raw marinated shrimp paste prepared by the emulsion without adding hot-pressed sturgeon cartilage collagen in Example 2; the commercial antifreeze group was composed of frozen raw marinated shrimp paste prepared by an aqueous solution containing 2% sucrose and 2% sorbitol (addition amount was 40%); the nanoemulsion solution group 30%, the nanoemulsion solution group 40% and the nanoemulsion solution group 50% prepared by the frozen raw marinated shrimp paste in Examples 1-3.

[0089] 1. Sensory evaluation

[0090] A 40-member sensory evaluation team was set up to conduct sensory evaluation on the frozen raw marinated shrimp paste. The product was sensory evaluated based on four aspects: color, smell, taste, and texture state. The evaluation of each dimension used a 25-point system for color, a 25-point system for smell, a 25-point system for taste, and a 25-point system for texture state. The evaluation indicators are shown in Table 4 below.

[0091] Table 4 Sensory evaluation table of frozen raw pickled shrimp paste

[0092]

[0093] from Figure 5 It can be seen that with the increase of the concentration of nanoemulsified solution, the sensory evaluation score of shrimp paste first increased and then decreased. When the nanoemulsified solution was added at 40vt.%, the sensory evaluation score was the highest, indicating that the quality of raw pickled shrimp paste was the best; when the concentration of nanoemulsified solution was increased, the sensory evaluation score decreased, mainly because the nanoemulsified solution affected the taste of raw pickled shrimp paste and covered up the fresh taste of shrimp paste. During the sensory evaluation, the sensory personnel described the raw pickled shrimp paste with the addition of nanoemulsified solution as having a delicate, smooth and dense taste similar to ice cream.

[0094] 2. Texture characteristics

[0095] The texture analyzer was used to measure the hardness, chewiness, and adhesiveness of the sample. The sample was taken out from the refrigerator after hardening for 48 hours for measurement. The parameter conditions were: the probe descending speed was 2mm / s, the measurement speed was 3mm / s, the probe test distance was kept at 15mm, the trigger force was pressed down into the shrimp paste with 10g, and the probe type was selected as TA / 45C. The two-cycle distance measurement method was used in the experiment, and the same sample was measured 3 times.

[0096] Texture is an important indicator for measuring raw marinated shrimp paste. The determination of texture can provide a clearer judgment on the structural changes of raw marinated shrimp paste. Figure 6 The results show that compared with ice cream, the overall hardness, chewiness, and adhesion of raw pickled shrimp paste are higher, which may be because raw pickled shrimp paste contains shrimp meat fibers, which is different from the emulsion-inflated frozen state of ice cream. Hardness is one of the important indicators of raw pickled shrimp paste texture, which can clearly compare the difference in the taste of raw pickled shrimp paste. Compared with the blank group, the raw pickled shrimp paste with commercial antifreeze and nanoemulsion solution added has a lower hardness. This is because commercial antifreeze and nanoemulsion solution have the effect of inhibiting the growth of ice crystals, and the ice crystals are less and smaller, so the hardness will be reduced.

[0097] Chewiness, or the bite in sensory evaluation, is a more intuitive feeling about raw marinated shrimp paste. The chewiness is correlated with the degree of consumer acceptance. The high chewiness is due to the fact that the shrimp paste slurry presents a relatively stable and compact structure, high hardness, high viscosity, and is not easy to soften, reflecting a strong bite. From the results, it can be seen that the blank group has the largest chewiness, the commercial antifreeze group and the nanoemulsion solution group have smaller chewiness, and the chewiness is the smallest when the nanoemulsion solution is added at 40vt.%. Therefore, according to the results of hardness and chewiness, it can be seen that the addition of nanoemulsion solution can give the raw marinated shrimp paste a delicate and dense ice cream taste. However, excessive use of nanoemulsion solution will cause excessive viscosity and even form a strong gel, which will not only reduce the foaming property, but also have a serious impact on the quality of the shrimp paste.

[0098] 3. Color difference

[0099] The color of the sample was measured by a colorimeter to measure the brightness (L * ) and the color components red and blue (a * and b * )’s chromaticity value.

[0100] Table 5 Grouping of color difference experiment of frozen raw pickled shrimp paste

[0101]

[0102] As can be seen from Table 5, the brightness value (L value) of the commercial ice cream group is the largest, while the a value and b value are both near 0, indicating that the color is color-free. Compared with all treatment groups, the brightness (L value) of the blank group without addition is the lowest, and the a value is also low, indicating that the brightness of the raw pickled shrimp paste in the blank group is darker and the color is white. Compared with the commercial antifreeze group, the addition of the nanoemulsion solution is better in terms of brightness and blueness. When the addition amount of the nanoemulsion solution is 40vt.%, the brightness value and blueness value reach the maximum value, and increasing the addition amount does not significantly improve, indicating that the addition of the nanoemulsion solution is beneficial to maintaining the color of the raw pickled shrimp paste.

[0103] 4. Scanning electron microscopy

[0104] After freeze-drying and vacuum gold spraying of each group of samples, images of the samples were taken with a scanning electron microscope at an accelerating voltage of 20Kv to observe the microscopic morphology and structure of the samples.

[0105] from Figure 7 The results of scanning electron microscopy show that the samples all show ice crystals of different sizes in microscopic morphology. The ice crystals in the blank group and the commercial ice cream group are larger, and there is no significant difference in the size of the ice crystals between the two groups; the size of the ice crystals in the raw pickled shrimp paste shows a decreasing trend with the increase in the amount of nanoemulsified solution added; when the nanoemulsified solution is 40vt.%, the ice crystals in the raw pickled shrimp paste are significantly reduced, and the size of the ice crystals is relatively uniform; when the amount of nanoemulsified solution added is increased, there is no significant difference in the ice crystals in the shrimp paste, indicating that when the amount of nanoemulsified solution added is greater than 40vt.%, it has begun to show recrystallization inhibition activity. Nanoemulsified solution can inhibit the growth of ice crystals, and it may contain peptide sequences similar to ice structural proteins.

[0106] 5. Glass transition temperature Tg

[0107] BSA group: The hot-pressed sturgeon cartilage collagen was replaced with bovine serum albumin without antifreeze activity, and the emulsion was made according to the preparation method, and the added amount was 40vt.% to make frozen raw marinated shrimp paste.

[0108] Weigh about 5 mg of sample and seal it in an aluminum crucible and place it in the sample pool. Use an empty aluminum crucible as a control, cool it with liquid nitrogen, and measure the glass transition temperature of the sample with DSC (differential scanning calorimeter). The experimental measurement procedure is: the initial equilibrium temperature is room temperature, cool down to -8°C at a rate of 10°C / min, keep the temperature constant for 2 minutes, then heat up to 10°C at a rate of 10°C, anneal at this temperature for 30 minutes, then cool down to -80°C at a rate of 10°C / min, keep the temperature constant for 2 minutes, and then heat up to 40°C at a rate of 10°C.

[0109] Since the Tg of shrimp paste is generally between -25 and -35℃, which is much lower than its actual storage temperature, during freezing, the ice crystals of shrimp paste continue to grow, and then recrystallize, affecting its taste. The increase in glass transition temperature can enhance the ability of shrimp paste to inhibit ice crystal recrystallization and resist melting, and can also improve its storage stability.

[0110] Depend on Figure 8 It can be seen that the Tg of the ice cream group is -27.84℃, the Tg of the blank group is -31.69℃, and the Tg of the control group is -29.93℃, with no significant difference between the two; when the amount of nanoemulsified solution added is 40vt.%, g begins to increase significantly; but after exceeding 0.5%, the degree of Tg increase is small. With the increase in the amount of nanoemulsified solution added, the Tg of raw pickled shrimp paste tends to increase. This may be due to the fact that the nanoemulsified solution is adsorbed on the surface of ice crystals as a stabilizer. The higher the adsorption coverage of the nanoemulsified solution on the surface of ice crystals, the stronger the effect of the nanoemulsified solution on inhibiting the continued growth of ice crystals, and the longer the time required for the shrimp paste to undergo partial glass transition, and the higher the Tg of the shrimp paste measured. Since the nanoemulsified solution increases the Tg of the shrimp paste, it inhibits the growth and recrystallization of shrimp paste ice crystals, so that the quality of the shrimp paste during the freezing process is improved.

[0111] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing frozen raw pickled shrimp paste with an ice cream-like taste, characterized in that: The following steps are involved: S1. Preparation of hot-pressed sturgeon cartilage collagen: cut the sturgeon cartilage into small pieces, soak and stir in 0.1 mol / L NaHCO3 solution for 0.5-1h, and wash until neutral; soak the washed sturgeon cartilage in 0.1 mol / L citric acid solution and stir for 0.5-1h, and wash until neutral; then mix the sturgeon cartilage with distilled water, extract at 115-121°C, 0.07-0.12Mpa for 30-50 min, centrifuge, take the supernatant, freeze-dry, and obtain hot-pressed sturgeon cartilage collagen powder, which is refrigerated for later use; S2. Preparation of nanoemulsified solution: add hot-pressed sturgeon cartilage collagen powder to cold water at 4°C, stir until completely dissolved to obtain collagen solution, add egg white, stir for 30 min until evenly mixed, obtain hot-pressed sturgeon cartilage collagen-egg white mixed solution as water phase, corn oil as oil phase, mix, add 2-3% of the mass of the mixed solution of soft white sugar, emulsify, homogenize into a coarse emulsion; ultrasonicate the coarse emulsion under ice water bath conditions, filter, and perform high pressure homogenization treatment under 25 MPa and 20°C conditions. The homogenized emulsion is placed in a refrigerated aging at 4°C for 10-15h to obtain a nanoemulsified solution; the amount of hot-pressed sturgeon cartilage collagen powder added in step S2 is 50-55wt%; the mass ratio of the egg white to the collagen solution is 1:(5-5.5); the volume ratio of the oil phase to the water phase is (2-2.5):(7.5-8); S3. marinating the raw materials: selecting fresh shrimps, adding seasonings, stirring evenly, and marinating at 4°C for 10 h to obtain marinated shrimps; S4. Marinating the shrimp paste: Add salt to the marinated shrimp, chop and mix until the shrimp paste is formed, add the nano-emulsified solution and the raw marinade, transfer to an ice cream machine, stir thoroughly at 2800-3000 r / min, add 3% cooked starch, and continue stirring until the mixture is smooth and uniform; S5. Preparation of frozen raw pickled shrimp paste: Take out the shrimp paste when the temperature is -8°C~-10°C, can and package it, and place it in a cold water treatment warehouse for ultra-high pressure treatment, sterilization, quick freezing, and frozen storage to obtain frozen raw pickled shrimp paste.

2. The method for preparing frozen raw pickled shrimp paste with an ice cream-like taste according to claim 1, characterized in that: In step S1, the material-liquid ratio of sturgeon cartilage to NaHCO3 solution is 1:(5-10); the material-liquid ratio of sturgeon cartilage to citric acid solution is 1:(5-10); and the material-liquid ratio of sturgeon cartilage to distilled water is 1:(4-5).

3. The method for preparing frozen raw pickled shrimp paste with an ice cream-like taste according to claim 1, characterized in that: In step S1, the centrifugal speed is 8000-10000 r / min, and the centrifugal time is 20-30 min.

4. The method for preparing frozen raw pickled shrimp paste with an ice cream-like taste according to claim 1, characterized in that: In the step S2, the homogenization speed is 16000 r / min, and the homogenization time is 2-3 min; the ultrasonic power is 300-500 W, and the ultrasonic time is 2-3 min.

5. The method for preparing frozen raw pickled shrimp paste with ice cream-like taste according to claim 1, characterized in that: In step S3, the seasoning is 5-10 g of salt, 3-5 g of white sugar, 5-10 mL of cooking wine, 5-10 mL of light soy sauce, 5-10 mL of balsamic vinegar, 1-3 mL of dark soy sauce, 10-20 g of garlic, 10-15 g of ginger, 5-10 g of chili and 10-20 g of coriander per 100 g of shrimp.

6. The method for preparing frozen raw pickled shrimp paste with ice cream-like taste according to claim 1, characterized in that: In step S4, the salt accounts for 1-2wt% of the pickled shrimp; the nano-emulsified solution accounts for 30-50vt% of the pickled shrimp; and the raw marinade accounts for 10-15vt% of the pickled shrimp.

7. The method for preparing frozen raw pickled shrimp paste with ice cream-like taste according to claim 1, characterized in that: The ultrahigh pressure treatment conditions in step S5 are as follows: the pressure is set to 600 MPa, the pressure is increased for 7 minutes, the pressure is maintained for 5 minutes, the pressure is reduced for 1 minute, and the temperature is lower than 15° C. throughout the process.

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