Method for removing fishy smell of minced fillet and improving gel property based on electric field effect and application of method

Abstract

The invention discloses a method for removing fishy smell of minced fillet and improving gel characteristics based on an electric field effect and application of the method, and relates to the technical field of production of minced fillet products. Comprising the following steps: treating surimi rinsing wastewater by utilizing a low-voltage direct-current electric field to obtain rinsing recovery liquid; rinsing the fresh surimi by using the rinsing recovery liquid, and introducing nitrogen microbubbles in the rinsing process to make full contact with the surimi; and rinsing with clear water, and dehydrating to finish the treatment. According to the method disclosed by the invention, the rinsing recovery liquid treated by the electric field is selected and has a synergistic effect with the introduced nitrogen microbubbles, so that the myofibrillar protein content and the moisture content of the rinsed minced fillet are relatively high, and the fat content and fishy smell substances are obviously reduced; the gel strength of the final gel product reaches 493.03 g.cm and meets the 3A-grade surimi standard (the gel strength is greater than or equal to 400 g.cm), and the quality, color and flavor of the surimi gel are effectively improved; the method is simple to operate, high in efficiency and suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of fish paste product production, and in particular to a method for removing fish paste smell and improving gel properties based on electric field effect and application thereof. Background Art

[0002] Surimi products are popular among consumers because of their high protein, low fat, fresh taste, convenience and speed. However, with the problems of overfishing of marine fish resources and the intensification of marine pollution, the raw materials of surimi products have gradually shifted from marine fish to freshwater fish. Although freshwater fish are widely available, they have low myofibrillar protein content, high fat content, strong endogenous protease and cathepsin activity, etc., which lead to poor gel properties (color, gel strength, water holding capacity, etc.) of surimi, greatly limiting its application in surimi processing. The common fishy smell problem of freshwater surimi not only affects the flavor of the product, but also reduces consumer acceptance.

[0003] At present, the main methods for removing fishy smell at home and abroad are to improve the rinsing process, physical method, chemical method and biological method. Although the traditional water rinsing process is simple to operate, it will produce a large amount of fish paste rinsing wastewater containing water-soluble protein, which increases the cost and difficulty of subsequent wastewater treatment. The water rinsing process also has problems such as low fish paste yield and incomplete fishy smell removal. Physical methods (such as sensory masking method) are convenient, effective, low-cost and highly flexible, but their role is only to cover up the fishy substances rather than remove them, and may destroy the original flavor of the fish paste. Although chemical methods (such as acid, alkali, salt, antioxidants and ozone treatment) can effectively reduce the fishy smell of fish paste, there are risks such as chemical residues, high cost and introduction of foreign odors. Although biological methods (such as enzyme preparations or microbial fermentation) can degrade fishy substances, they are mainly suitable for liquid or fermented fish products and have a limited scope of application. Therefore, the development of an efficient and environmentally friendly deodorization technology is of great significance to improving the color and quality of freshwater fish paste products. Summary of the invention

[0004] In view of the deficiencies of the above prior art, the present invention provides a method for removing fishy smell and improving gel properties of fish paste based on electric field effect and its application. The present invention uses the supernatant of fish paste rinsing wastewater treated with a low-voltage DC electric field to rinse the fresh fish paste to be treated, and nitrogen microbubbles are introduced during the rinsing process, which not only effectively reduces the fat content and fishy smell in the fish paste, but also significantly improves the gel strength, water retention and puncture performance of the fish paste products, improves the color of the fish paste products, and meets the 3A fish paste standard of gel strength ≥400 g·cm. It is specifically achieved through the following technologies.

[0005] A method for removing fishy smell from surimi and improving gel properties based on electric field effect, comprising the following steps:

[0006] Take the fish surimi rinsing wastewater, treat it with a low-voltage direct current electric field, and centrifuge to obtain the supernatant to obtain the rinsing recovery liquid;

[0007] The fresh fish paste to be processed is rinsed for the first time using the rinsing recovery liquid; the fresh fish paste to be processed is rinsed for the second time using clean water and left to stand to complete the processing of the fresh fish paste to be processed; during the first rinsing and the second rinsing, nitrogen is introduced throughout the process to generate nitrogen microbubbles to contact the fresh fish paste to be processed.

[0008] The fish paste rinsing wastewater used in the present invention refers to the supernatant obtained by simply decolorizing the initially collected fish paste rinsing wastewater with activated carbon and then subjecting it to centrifugal sedimentation treatment.

[0009] In order to improve the gel properties of surimi products, the present invention uses the rinsing recovery liquid treated by low-voltage DC electric field to rinse the fresh surimi for the first time, and uses clean water for the second rinse; and nitrogen is introduced during the two rinses to generate microbubbles. It is finally found that the synergistic cooperation of the two process steps can significantly improve the gel properties of surimi.

[0010] The present invention applies a low-voltage DC electric field to the fish surimi rinsing wastewater, which can also promote the rapid aggregation and precipitation of negatively charged protein molecules in the fish surimi rinsing wastewater, thereby achieving efficient solid-liquid separation and protein recovery. 2 O 2 ), when the source of fish surimi rinsing wastewater is tap water, it will also electrolyze to produce hypochlorous acid (HClO) / hypochlorite ions (ClO - ), chlorine and other substances, which can effectively degrade organic matter that produces fishy smell (such as trimethylamine, aldehydes, ketones, etc.), and reduce the fishy smell when rinsing the fresh fish paste to be processed. The nitrogen introduced can also inhibit lipid peroxidation and reduce the generation of fishy substances such as aldehydes (such as hexanal and nonanal) and sulfides.

[0011] The invention utilizes a low-voltage direct current electric field to treat fish paste rinsing wastewater, and uses the treated rinsing recovery liquid for rinsing fresh fish paste, thereby realizing the recycling of water resources and providing a highly efficient and environmentally friendly technical means for fish paste processing enterprises.

[0012] Furthermore, the mass ratio of the fresh fish paste to be processed to the rinsing recovery liquid is 1:(2-6).

[0013] Furthermore, the mass ratio of the fresh fish paste to be processed to the rinsing recovery liquid is 1:4.

[0014] Furthermore, the method of using low-voltage direct current electric field treatment is to treat at 10-30°C and 30-50 V for 20-40 minutes.

[0015] Furthermore, the method of low voltage direct current electric field treatment is to treat at 25°C and 50 V for 30 min.

[0016] Furthermore, the method of taking the supernatant by centrifugation is 8000-10000 r / min for 10-20 min.

[0017] Furthermore, the method of obtaining the supernatant by centrifugation is 10000 r / min for 15 min.

[0018] Furthermore, the first rinsing condition is 4°C±1°C for 1-9 min, and the standing time after rinsing is 10-30 min.

[0019] Furthermore, the first rinsing condition is rinsing at 4° C. for 9 minutes, and the standing time after rinsing is 20 minutes.

[0020] Furthermore, the amount of nitrogen introduced per unit volume of the rinsing recovery liquid is 1.0-3.0 mg / (min·L).

[0021] Furthermore, the amount of nitrogen introduced into the unit volume of the rinsing recovery liquid is 3 mg / (min·L).

[0022] Furthermore, based on any of the above methods for removing fishy smell and improving gel properties of surimi based on electric field effect, after the second rinsing and standing, dehydration, chopping, shaping, heating and cooling are sequentially performed;

[0023] The chopping method is: adding salt and ice water at 4°C±1°C, and chopping at 2000-3000 r / min for 3 minutes.

[0024] Furthermore, the amount of salt added is 1.5-2% of the mass of the dehydrated surimi, and the amount of ice water added is 70-80% of the mass of the dehydrated surimi.

[0025] Furthermore, the heating method is heating in a 30-40°C water bath for 20-40 min, and then heating in a 80-90°C water bath for 10-30 min; the cooling method is cooling in 0-4°C ice water for 10-30 min.

[0026] Furthermore, the heating method is heating in a 40°C water bath for 30 min and then heating in a 90°C water bath for 10 min; the cooling method is cooling in 0°C ice water for 20 min.

[0027] Compared with the prior art, the present invention is beneficial in that:

[0028] 1. The present invention uses a rinsing recovery liquid treated by a low-voltage direct current electric field to play a synergistic role with nitrogen microbubbles, which can not only effectively reduce the fishy smell in the surimi gel product, but also promote the cross-linking between protein molecules, significantly improve the gel properties of the surimi, and the gel strength reaches 493.03 g·cm, which meets the 3A grade surimi standard (gel strength ≥400 g·cm).

[0029] 2. The method provided by the present invention is simple in process, easy to operate, and does not require the addition of any chemical reagents. The rinsing recovery liquid used is obtained by treating the fish paste rinsing wastewater with a low-voltage direct current electric field. Its only oxidation byproduct is water, and organic matter, heavy metals and other substances are very small. It can be directly used for rinsing fresh fish paste or cleaning raw fish, realizing the recycling of wastewater and significantly improving the economic benefits of fish paste and its processing enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a graph showing the effect of different rinsing methods on the water holding capacity of surimi gel. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In some embodiments of the present invention, the method for removing fishy smell from surimi and improving gel properties comprises the following steps:

[0033] Take the fish surimi rinsing wastewater, treat it with a low-voltage direct current electric field, and centrifuge to obtain the supernatant to obtain the rinsing recovery liquid;

[0034] The fresh fish paste to be processed is rinsed for the first time using the rinsing recovery liquid; the fresh fish paste to be processed is rinsed for the second time using clean water and left to stand to complete the processing of the fresh fish paste to be processed; during the first rinsing and the second rinsing, nitrogen is also introduced to generate nitrogen microbubbles to contact the fresh fish paste to be processed.

[0035] Optionally, the fresh minced fish processed by the present invention can be minced fish from any source. In the following specific embodiments, for the sake of comparison, silver carp minced fish purchased from the farmers' market of Huazhong Agricultural University without fish head, fish skin, viscera and fish bones is used.

[0036] Optionally, the fish paste rinsing wastewater refers to the supernatant obtained by simply decolorizing the initially collected fish paste rinsing wastewater with activated carbon and subjecting it to a centrifugal sedimentation treatment.

[0037] Optionally, the mass ratio of the fresh fish paste to be processed to the rinsing recovery liquid is 1:(2-6); specifically, 1:4 can be selected.

[0038] Optionally, the method of using low-voltage direct current electric field treatment is to treat at 10-30°C and 30-50 V for 20-40 min; specifically, the method can be to treat at 25°C and 50 V for 30 min.

[0039] Optionally, the method of taking the supernatant by centrifugation is 8000-10000 r / min for 10-20 min; specifically, the method of centrifugation can be 10000 r / min for 15 min.

[0040] Optionally, the first rinsing condition is rinsing at 4°C±1°C for 1-9 min, and the standing time after rinsing is 10-30 min; specifically, rinsing at 4°C for 9 min, and the standing time after rinsing is 20 min.

[0041] Optionally, the amount of nitrogen introduced per unit volume of the rinsing recovery liquid is 1.0-3.0 mg / (min·L); specifically, the amount of nitrogen introduced can be 3 mg / (min·L).

[0042] After the above-mentioned treatments of removing the fishy smell and improving the gel properties of the surimi, after the second rinsing and standing, the surimi is further subjected to dehydration, chopping, shaping, heating and cooling treatments in sequence;

[0043] The chopping method is: adding salt and ice water at 4°C±1°C, and chopping at 2000-3000 r / min for 3 minutes.

[0044] Optionally, during chopping, the amount of salt added is 1.5-2% of the mass of the dehydrated fish paste, and the amount of ice water added is 70-80% of the mass of the dehydrated fish paste.

[0045] Optionally, the heating method is heating in a 30-40°C water bath for 20-40 min, and then heating in a 80-90°C water bath for 10-30 min; the cooling method is cooling in 0-4°C ice water for 10-30 min.

[0046] Specifically, the heating method may be heating in a 40° C. water bath for 30 min, and then heating in a 90° C. water bath for 10 min; the cooling method may be cooling in 0° C. ice water for 20 min.

[0047] The following examples and comparative examples are designed according to the experimental actual scheme in Table 1 below.

[0048] Table 1

[0049] Example 1

[0050] The method for removing fishy smell and improving gel properties provided in this embodiment comprises the following steps:

[0051] (1) The surimi rinsing wastewater was treated with a low-voltage direct current electric field (50 V) at 25°C for 30 min, dehydrated and centrifuged at 10,000 r / min for 15 min, and the supernatant was collected to obtain the rinsing recovery liquid.

[0052] (2) First rinsing: Use rinsing recovery liquid to rinse the fresh fish paste. The mass ratio of rinsing recovery liquid to fresh fish paste is 1:4, and the rinsing time is 9 minutes. After rinsing, let it stand for 20 minutes, dehydrate and centrifuge at 10,000 r / min for 15 minutes to obtain the first rinsed fish paste.

[0053] During the first rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0054] (3) Second rinsing: Use clean water instead of the rinsing recovery liquid to rinse the fish paste after the first rinsing. The mass ratio of clean water to the fish paste after the first rinsing is 1:4. The rinsing method is the same as step (2) to obtain the fish paste after the second rinsing.

[0055] During the second rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0056] (4) Based on the mass of the fish paste after the second rinse, add 2% salt and 80% ice water to the fish paste after the second rinse, and chop at 2000 r / min for 3 min.

[0057] (5) Use a sausage stuffer to fill in sausage casings with a diameter of 20 mm and seal the casings to form the sausage.

[0058] (6) The sealed surimi gel was heated in two stages, with the first stage heating temperature at 40°C for 30 min and the second stage heating temperature at 90°C for 10 min to obtain a thermoformed surimi gel.

[0059] (7) Place it in 0℃ ice water and cool for 20 minutes to obtain the final fish paste product.

[0060] Comparative Example 1

[0061] This comparative example provides a method for removing fishy smell from minced fish and improving gel properties. The difference from Example 1 is that the rinsing recovery liquid is replaced with clean water during the first rinsing. Specifically, the following steps are included:

[0062] (1) First rinsing: Use clean water to rinse the fresh surimi. The mass ratio of clean water to fresh surimi is 1:4, and the rinsing time is 9 min. After rinsing, let it stand for 20 min, dehydrate and centrifuge at 10,000 r / min for 15 min to separate the surimi.

[0063] During the first rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0064] (2) Second rinsing: The same as step (3) of Example 1, to obtain fish paste after the second rinsing.

[0065] During the first rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0066] No external electric field treatment was applied during the first rinsing and the second rinsing. The subsequent steps were the same as steps (4) to (7) of the embodiment to obtain the final surimi product.

[0067] Comparative Example 2

[0068] This comparative example provides a method for removing fishy smell from minced fish and improving gel properties. The difference from Example 1 is that the rinsing recovery liquid is replaced with clean water during the first rinsing, and an external electric field (50 V) is applied during the first rinsing process; and nitrogen microbubbles are not introduced during the second rinsing. Specifically, the following steps are included:

[0069] (1) First rinsing: Use clean water to rinse the fresh surimi. The mass ratio of clean water to fresh surimi is 1:3, and the rinsing time is 3 min. After rinsing, let it stand for 20 min, dehydrate and centrifuge at 10000 r / min for 15 min to obtain the first rinsed surimi. Apply a 50 V external electric field during the first rinsing process.

[0070] (2) Second rinsing: Rinse the surimi for the second time with clean water, the mass ratio of clean water to fresh surimi being 1:3, and the rinsing time being 3 min. After rinsing, let it stand for 20 min, dehydrate and centrifuge at 10,000 r / min for 15 min, and separate the surimi for the second rinse.

[0071] The subsequent steps are the same as steps (4) to (7) of Example 1 to obtain the final surimi product.

[0072] Comparative Example 3

[0073] This comparative example provides a method for removing fishy smell from minced fish and improving gel properties. The difference from Example 1 is that the rinsing recovery liquid is replaced with clean water during the first rinsing, and the clean water is replaced with the rinsing recovery liquid during the second rinsing. Specifically, the following steps are included:

[0074] (1) The surimi rinsing wastewater was treated with a low-voltage direct current electric field (50 V) at 25°C for 30 min, dehydrated and centrifuged at 10,000 r / min for 15 min, and the supernatant was collected to obtain the rinsing recovery liquid.

[0075] (2) First rinsing: Use clean water to rinse the fresh surimi. The mass ratio of clean water to fresh surimi is 1:4, and the rinsing time is 9 min. After rinsing, let it stand for 20 min, dehydrate and centrifuge at 10,000 r / min for 15 min to separate the surimi for the first rinse.

[0076] During the first rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0077] (3) Second rinsing: The surimi from the first rinse is rinsed with the rinsing recovery liquid. The mass ratio of the rinsing recovery liquid to the surimi from the first rinse is 1:4, and the rinsing time is 9 min. After rinsing, the surimi is allowed to stand for 20 min, and then dehydrated and centrifuged at 10,000 r / min for 15 min to obtain the surimi from the second rinse.

[0078] During the second rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0079] The subsequent steps are the same as steps (4) to (7) of Example 1 to obtain the final surimi product.

[0080] Comparative Example 4

[0081] This comparative example provides a method for removing fishy smell from minced fish and improving gel properties. The difference from Example 1 is that the rinsing recovery liquid is replaced with clean water during the first rinsing, and an external DC electric field is introduced. Specifically, the following steps are included:

[0082] (1) First rinsing: Use clean water to rinse the fresh surimi. The mass ratio of clean water to fresh surimi is 1:4, and the rinsing time is 9 min. After rinsing, let it stand for 20 min, dehydrate and centrifuge at 10,000 r / min for 15 min to separate the surimi for the first rinse.

[0083] During the first rinsing process, nitrogen was generated and introduced using a microbubble generator at a rate of 3 mg / (min·L) to generate nitrogen microbubbles so that the nitrogen microbubbles were in full contact with the raw fish paste; a 50 V DC electric field was also applied.

[0084] (2) Second rinsing: Use clean water to rinse the fish paste after the first rinse. The mass ratio of clean water to the fish paste after the first rinse is 1:4, and the rinsing time is 9 minutes. After rinsing, let it stand for 20 minutes, dehydrate and centrifuge at 10,000 r / min for 15 minutes to obtain the second rinsed fish paste.

[0085] During the second rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0086] The subsequent steps are the same as steps (4) to (7) of Example 1 to obtain the final surimi product.

[0087] Comparative Example 5

[0088] This comparative example provides a method for removing fishy smell from minced fish and improving gel properties. The difference from Example 1 is that the clean water is replaced with rinsing recovery liquid during the second rinsing. Specifically, the following steps are included:

[0089] (1) The surimi rinsing wastewater was treated with a low-voltage direct current electric field (50 V) at 25°C for 30 min, dehydrated and centrifuged at 10,000 r / min for 15 min, and the supernatant was collected to obtain the rinsing recovery liquid.

[0090] (2) First rinsing: Use rinsing recovery liquid to rinse the fresh fish paste. The mass ratio of rinsing recovery liquid to fresh fish paste is 1:4, and the rinsing time is 9 min. After rinsing, let it stand for 20 min, dehydrate and centrifuge at 10,000 r / min for 15 min, and separate the first rinsed fish paste.

[0091] During the first rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0092] (3) Second rinsing: The surimi from the first rinse is rinsed with the rinsing recovery liquid. The mass ratio of the rinsing recovery liquid to the surimi from the first rinse is 1:4, and the rinsing time is 9 min. After rinsing, the surimi is allowed to stand for 20 min, and then dehydrated and centrifuged at 10,000 r / min for 15 min to obtain the surimi from the second rinse.

[0093] During the second rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0094] The subsequent steps are the same as steps (4) to (7) of Example 1 to obtain the final surimi product.

[0095] Comparative Example 6

[0096] This comparative example provides a method for removing fishy smell from minced fish and improving gel properties. The difference from Example 1 is that the rinsing recovery liquid is replaced with ordinary minced fish rinsing wastewater during the first rinsing.

[0097] Ordinary fish paste rinsing wastewater is the wastewater obtained after rinsing fresh fish paste with clean water and removing the fish paste. The mass ratio of clean water to fresh fish paste is 1:4, and the rinsing time is 9 minutes; after rinsing, it is left to stand for 20 minutes and dehydrated by centrifugation at 10,000 r / min for 15 minutes.

[0098] The specific steps include:

[0099] (1) First rinsing: Ordinary surimi rinsing wastewater was used to rinse the fresh surimi. The mass ratio of ordinary surimi rinsing wastewater to fresh surimi was 1:4, and the rinsing time was 9 min. After rinsing, the surimi was allowed to stand for 20 min, dehydrated and centrifuged at 10,000 r / min for 15 min, and the surimi for the first rinse was separated.

[0100] During the first rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0101] (3) Second rinsing: Use clean water to rinse the fish paste after the first rinse. The mass ratio of clean water to the fish paste after the first rinse is 1:4, and the rinsing time is 9 minutes. After rinsing, let it stand for 20 minutes, dehydrate and centrifuge at 10,000 r / min for 15 minutes to obtain the second rinsed fish paste.

[0102] During the second rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0103] The subsequent steps are the same as steps (4) to (7) of Example 1 to obtain the final surimi product.

[0104] Comparative Example 7

[0105] This comparative example provides a method for removing fishy smell from minced fish and improving gel properties. The difference from Example 1 is that during the first rinsing, the rinsing recovery liquid is replaced with ordinary minced fish rinsing wastewater, and an external DC electric field is introduced. Specifically, the following steps are included:

[0106] (1) First rinsing: Ordinary surimi rinsing wastewater was used to rinse the fresh surimi. The mass ratio of ordinary surimi rinsing wastewater to fresh surimi was 1:4, and the rinsing time was 9 min. After rinsing, the surimi was allowed to stand for 20 min, dehydrated and centrifuged at 10,000 r / min for 15 min, and the surimi for the first rinse was separated.

[0107] During the first rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles so that the nitrogen microbubbles were in full contact with the raw material surimi; and a 50 V DC electric field was also applied.

[0108] (2) Second rinsing: Use clean water to rinse the fish paste after the first rinse. The mass ratio of clean water to the fish paste after the first rinse is 1:4, and the rinsing time is 9 minutes. After rinsing, let it stand for 20 minutes, dehydrate and centrifuge at 10,000 r / min for 15 minutes to obtain the second rinsed fish paste.

[0109] During the second rinsing process, a microbubble generator was used to generate and introduce nitrogen at a rate of 3 mg / (min·L) to generate nitrogen microbubbles, which were then fully contacted with the raw fish paste.

[0110] The subsequent steps are the same as steps (4) to (7) of Example 1 to obtain the final surimi product.

[0111] Comparative Example 8

[0112] This comparative example provides a method for removing fishy smell from minced fish and improving gel properties. The difference from Example 1 is that the rinsing recovery liquid is replaced with ordinary minced fish rinsing wastewater during the first rinsing, and an external DC electric field is introduced, and nitrogen microbubbles are not introduced during the first and second rinsing. Specifically, the following steps are included:

[0113] (1) First rinsing: Ordinary surimi rinsing wastewater was used to rinse the fresh surimi. The mass ratio of ordinary surimi rinsing wastewater to fresh surimi was 1:4, and the rinsing time was 9 min. After rinsing, the surimi was allowed to stand for 20 min, dehydrated and centrifuged at 10,000 r / min for 15 min, and the surimi for the first rinse was separated. A 50 V DC electric field was also applied during the first rinse.

[0114] (2) Second rinsing: Use clean water to rinse the fresh surimi. The mass ratio of clean water to the surimi after the first rinse is 1:4, and the rinsing time is 9 minutes. After rinsing, let it stand for 20 minutes, dehydrate and centrifuge at 10,000 r / min for 15 minutes to obtain the surimi after the second rinse.

[0115] The subsequent steps are the same as steps (4) to (7) of Example 1 to obtain the final surimi product.

[0116] Test Example 1: Color analysis of the surimi products prepared in the above examples and comparative examples

[0117] The color analysis of the surimi gel of Example 1 and Comparative Examples 1-8 was performed as follows: the color of the surimi gel sample was measured using a high-precision spectrophotometer. The sample was cut into uniform slices with a height of 20 mm and a thickness of 5 mm, and its L* (brightness), a* (redness), and b* (blueness) values ​​were measured. Four parallels were measured for each group of samples. The calculation formula of the whiteness value W is as follows:

[0118] .

[0119] Table 2 Effects of different rinsing methods on the color of surimi gel

[0120]

[0121] Note: Different letters indicate significant differences among samples (P < 0.05).

[0122] The color results of the surimi gel treated with different rinsing methods are shown in Table 2 above. It can be seen that whether adding 1 part of rinsing recovery liquid or 2 parts of rinsing recovery liquid, the whiteness value is slightly improved compared with Comparative Example 1. Therefore, adding rinsing recovery liquid during the rinsing process of the surimi will not have an adverse effect on the color of the surimi gel sample, and can improve the whiteness of the surimi gel to a certain extent and improve the color of the surimi gel.

[0123] Test Example 2: Texture analysis of the surimi products prepared in the above examples and comparative examples

[0124] The texture analysis of the surimi gel of Example 1 and Comparative Examples 1-8 was performed. The specific analysis method was as follows: the surimi gel sample was cut into a cylinder of 10×10×20 mm, and the surimi gel strength was measured using a texture analyzer. Measurement parameters: probe model was P / 2.5S, puncture distance was 15 mm, pre-measurement speed was 2 mm / s, test speed was 1 mm / s, and post-measurement speed was 2 mm / s. Four parallels were set for each group, and the test results were averaged.

[0125] Table 3 Effects of different rinsing methods on the properties of surimi gel

[0126]

[0127] Note: Different letters indicate significant differences among samples (P < 0.05).

[0128] The gel properties of surimi corresponding to different rinsing methods are shown in Table 3. The gel strength of surimi of Example 1 reaches a maximum of 493.03 g cm, which is 15.83% higher than that of Comparative Example 1, 19.73% higher than that of Comparative Example 2, 3.51% higher than that of Comparative Example 3, 9.78% higher than that of Comparative Example 4, 6.58% higher than that of Comparative Example 5, 18.61% higher than that of Comparative Example 6, 12.78% higher than that of Comparative Example 7, and 22.41% higher than that of Comparative Example 8.

[0129] By comparing Example 1 with Comparative Example 1, or comparing Example 1 with Comparative Example 6, it can be seen that when only nitrogen is introduced during rinsing and no electric field is applied, the effect of improving the gel strength of the surimi is not as good as that of Example 1, regardless of whether clean water or ordinary surimi rinsing wastewater is used for the first rinsing.

[0130] By comparing Example 1 with Comparative Example 4, or Example 1 with Comparative Example 7, it can be seen that when nitrogen is introduced during rinsing and an electric field is applied during the first rinsing, the effect of improving the gel strength of the surimi is not as good as that of Example 1, and Comparative Example 4 is stronger than Comparative Example 1, and Comparative Example 7 is stronger than Comparative Example 6. This shows that even if an electric field is applied during the first rinsing, the improvement of the gel strength of the surimi is relatively limited. This may be because the application of an electric field during the first rinsing process causes thermal denaturation of local proteins, destroys the protein structure, and reduces its gel strength.

[0131] By comparing Comparative Examples 1, 2 and 4, or Comparative Examples 6-8, it can be seen that no matter whether clean water or ordinary fish paste rinsing wastewater is used, the lack of any of the two processes of "applying an electric field during rinsing" and "introducing nitrogen" will affect the final fish paste gel performance.

[0132] By comparing Example 1 and Comparative Example 3, it can be seen that when the order of rinsing recovery liquid and clean water is changed, when clean water is used first and then rinsing recovery liquid is used, the gel strength of the surimi cannot be improved to the maximum extent. This may be because the rinsing recovery liquid is used for the first rinsing, and some of the protein contained in it can form a protective layer, reducing the initial loss of protein in the fresh surimi, and then the second clean water rinsing further removes impurities, thereby improving the gel strength of the surimi; while the first rinsing uses clean water, which will dissolve and wash away a large amount of soluble protein, resulting in a large initial loss of protein, resulting in a weaker final gel network structure.

[0133] By comparing Example 1 and Comparative Example 5, it can be seen that when the clean water in the second rinse is replaced with the rinse recovery liquid, the fish paste gel performance is worse than that in Example 1. This may be because the rinse recovery liquid is used again in the second rinse, which will cause excessive oxidation of myofibrillar protein and affect the fish paste gel performance.

[0134] After analysis, it may be because:

[0135] Nitrogen (N 2 ) as an inert gas can protect the free sulfhydryl (-SH) in the active center of transglutaminase (TGase) from inactivation, inhibit the rupture of lysosomal membrane, reduce the content of cathepsins, and delay its degradation of myofibrillar protein; thereby enhancing the protein cross-linking degree and ultimately improving the gel strength of fish paste.

[0136] The rinse recovery liquid treated with low-voltage DC electric field can promote the moderate expansion of the myofibril structure of the surimi gel, exposing more hydrophobic groups, thereby enhancing the protein cross-linking degree and further improving the gel strength of the surimi. 2 ) may activate endogenous enzymes (such as transglutaminase, TGase) and promote protein cross-linking. In addition, the rinsing recovery liquid contains a part of small molecule peptides or denatured proteins, which may also be adsorbed to the surface of fresh surimi during the rinsing process, filling the gaps in the gel network and improving the performance and texture of surimi gel.

[0137] It can be seen that the synergistic cooperation of the two process steps can promote the cross-linking between protein molecules in surimi, thereby significantly improving the gel properties of surimi.

[0138] Test Example 3: Water holding capacity analysis of the surimi products prepared in the above examples and comparative examples

[0139] The surimi gel of Example 1 and Comparative Examples 1-8 was subjected to water holding capacity analysis. The specific method was as follows: the surimi gel was cut into slices with a thickness of about 5 mm, and the mass m was accurately weighed. 0 Wrap the sample with 3 layers of filter paper and place it at the bottom of the centrifuge tube. Centrifuge at 5000 r / min for 15 min. After centrifugation, take out the sample and weigh the mass m again. 1 The water holding capacity (WHC) of surimi gel is calculated according to the following formula:

[0140] ;

[0141] Where: m 0 is the mass of surimi gel, in g; m 1 is the mass of the sample surimi gel after centrifugation, in g.

[0142] The water holding capacity of surimi gel under different rinsing methods is shown in Figure 2. Figure 1 It can be seen that compared with comparative examples 1-8, the water holding capacity of the surimi gel can be significantly improved by first using the rinsing recovery liquid and then rinsing (P < 0.05).

[0143] This may be because the combined effect of the rinsing recovery liquid and the nitrogen gas process promotes cross-linking between protein molecules, enhances the stability of the protein network, and binds more water in the gel network. Using clean water for the second rinse can remove excess ions and small molecular impurities accumulated in the recovery liquid to prevent them from interfering with protein cross-linking.

[0144] Test Example 4: Sensory evaluation of the surimi products prepared in the above examples and comparative examples

[0145] The surimi gels of Example 1 and Comparative Examples 1-8 were subjected to sensory evaluation, and the specific method was as follows:

[0146] Ten students majoring in food were selected, with a male-female ratio of 1:1 and aged between 20 and 30 years. According to GB / T 16291.1-2012, their odor recognition and observation abilities were trained, and then the fish surimi gel samples were sensory evaluated. According to the sensory analysis terminology of GB / T 10221-2012 and the sensory evaluation guide of GB / T 37062-2018 for aquatic products, the fish surimi gel was evaluated in terms of earthy smell, inherent smell of fish meat, fishy smell, and sour taste. The odor intensity was evaluated on a scale of 0-10, with 1 point indicating that the odor was very light and 10 points indicating that the odor was very strong. The final score of the odor was averaged.

[0147] The results of the gel strength of surimi treated with different rinsing methods are shown in Table 4 below.

[0148] Table 4 Descriptive sensory evaluation of the odor of surimi gel treated by different rinsing methods

[0149]

[0150] Note: Different letters indicate significant differences among samples (P < 0.05).

[0151] As can be seen from Table 4 above, earthy smell is one of the most important factors affecting the flavor of freshwater fish, mainly caused by geosmin and trimethylamine (TMA). As can be seen from Table 4, using fish surimi rinsing recovery liquid to rinse fish surimi (Example 1, Comparative Example 3, Comparative Example 5) can significantly reduce the earthy smell of fish surimi gel, among which Example 1 has the most significant effect. The fishy smell is caused by aldehyde compounds (such as hexanal and nonanal) produced by the oxidation of unsaturated fatty acids in freshwater fish, which is the characteristic flavor of oxidized fish oil. Example 1 significantly reduces the fishy smell of fish surimi gel, indicating that this treatment method has the best deodorization effect. Compared with other comparative examples, Example 1 uses fish surimi rinsing recovery liquid to rinse fish surimi to significantly increase the fishy aroma of fish surimi gel.

[0152] It can also be seen from Table 4 that rinsing the surimi with the surimi rinsing recovery liquid (Example 1, Comparative Example 3, Comparative Example 5) can significantly reduce the rancid smell of the surimi gel, among which only the surimi gel in Example 1 has the lowest rancid smell. This may be because the active ingredients in the rinsing recovery liquid (such as low concentration of chloride ions, residual protease, etc.) can effectively inhibit the formation of trimethylamine, a fishy substance, and the second rinsing with clean water can remove the volatile fishy substances (such as TMA and piperidine compounds) that have been formed in the surimi.

[0153] Test Example 5: Volatile component test of the surimi products prepared in the above examples and comparative examples

[0154] The surimi gels of Example 1 and Comparative Examples 1-8 were tested for volatile components, and the specific testing method was as follows:

[0155] (1) Solid phase microextraction: Place 3.0 g of sample in a 20 mL headspace vial, add 6 mL of saturated NaCl and 10 μL of internal standard TMP (100 mg / kg), place in a magnetic rotor, and quickly cover. Then place in a 60°C magnetic stirring water bath for 30 min. Then insert the aged extraction head into the headspace of the sample bottle.

[0156] (2) Adsorb at 60°C for 30 min, insert into the GC injection port for desorption for 5 min, and perform GC-MS analysis. All samples were measured in triplicate.

[0157] Chromatographic (GC) conditions: The temperature program was an initial temperature of 40 °C, maintained for 3 min, then increased to 90 °C at a rate of 5 °C / min, maintained for 5 min, then increased to 250 °C at a rate of 10 °C / min, maintained for 6 min, and the injection port temperature was maintained at 250 °C;

[0158] Mass spectrometry (MS) conditions: EI ion source, electron energy 70 eV; ion source temperature 250 °C, ion scan range 35-500 m / z, detector voltage 1000 V.

[0159] (3) Volatile compounds were compared and analyzed using the NIST Chemistry WebBook mass spectral library and the Willey standard library in a triple quadrupole gas chromatograph-mass spectrometer (Agilent Instruments, Singapore, model: 7000D). The substance with the highest matching degree was the target volatile flavor substance. The concentration of each volatile compound in the sample was quantified by the ratio of the peak area of ​​each compound to the internal standard compound, in μg / kg.

[0160] The fishy smell of freshwater fish mainly comes from volatile compounds such as aldehydes, alcohols, and ketones produced by unsaturated fatty acids, among which hexanal, nonanal, decanal, 1-octen-3-ol, and 1-octen-3-one are the main flavor-active volatile substances. The results of the volatile components of fish paste treated with different rinsing methods are shown in Table 5.

[0161] Table 5 Effects of different rinsing methods on the volatile components of surimi gel

[0162] Note: Different letters indicate significant differences among samples (P < 0.05).

[0163] From Table 5 above, it can be seen that the hexanal concentration of Comparative Example 1 is 263.78 μg / kg, the nonanal concentration is 556.34 μg / kg, the decanal concentration is 439.23 μg / kg, the 1-octen-3-ol concentration is 793.32 μg / kg, and the 1-octen-3-one concentration is 31.56 μg / kg. Compared with Comparative Example 1, after treatment with different rinsing methods, the contents of hexanal, nonanal and decanal, 1-octen-3-ol and 1-octen-3-one can be significantly reduced, among which Example 1 has the largest degree of reduction. This may be because the dual effects of rinsing recovery liquid and nitrogen introduction further degrade the residual odor substances and inhibit fat oxidation and microbial activity. Nitrogen microbubbles hinder the binding of odor molecules to proteins through surface adsorption.

[0164] The above specific embodiments describe the implementation of the present invention in detail, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, the technical solution of the present invention can be modified and changed in many simple ways, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A method for removing fishy smell from surimi and improving gel properties based on electric field effect, characterized in that: The following steps are involved: Take the fish surimi rinsing wastewater, treat it with a low-voltage direct current electric field, and centrifuge to obtain the supernatant to obtain the rinsing recovery liquid; The fresh fish paste to be processed is rinsed for the first time using the rinsing recovery liquid; the fresh fish paste to be processed is rinsed for the second time using clean water and left to stand to complete the processing of the fresh fish paste to be processed; during the first rinsing and the second rinsing, nitrogen is introduced throughout the process to generate nitrogen microbubbles to contact the fresh fish paste to be processed.

2. The method for removing fishy smell from surimi and improving gel properties based on electric field effect according to claim 1, characterized in that: The mass ratio of the fresh fish paste to be processed to the rinsing recovery liquid is 1:(2-6).

3. The method for removing fishy smell from surimi and improving gel properties based on electric field effect according to claim 1, characterized in that: The method of using low voltage direct current electric field treatment is to treat at 10-30°C and 30-50 V for 20-40 min.

4. The method for removing fishy smell from surimi and improving gel properties based on electric field effect according to claim 1, characterized in that: The method of taking the supernatant by centrifugation is 8000-10000 r / min for 10-20 min.

5. The method for removing fishy smell from surimi and improving gel properties based on electric field effect according to claim 1, characterized in that: The first rinsing condition is 4°C±1°C for 1-9 min, and the standing time after rinsing is 10-30 min.

6. The method for removing fishy smell from surimi and improving gel properties based on electric field effect according to claim 1, characterized in that: The nitrogen flow rate per unit volume of the rinsing recovery liquid is 1.0-3.0 mg / (min·L).

7. The method for removing fishy smell from surimi and improving gel properties based on electric field effect according to any one of claims 1 to 6, characterized in that: After the second rinsing and standing, dehydration, chopping, shaping, heating and cooling are performed in sequence; The chopping method is: adding salt and ice water at 4°C±1°C, and chopping at 2000-3000 r / min for 3 min.

8. The method for removing fishy smell from surimi and improving gel properties based on electric field effect according to claim 7, characterized in that: The amount of salt added is 1.5-2% of the mass of the dehydrated surimi, and the amount of ice water added is 70-80% of the mass of the dehydrated surimi.

9. The method for removing fishy smell from surimi and improving gel properties based on electric field effect according to claim 7, characterized in that: The heating method is heating in a 30-40° C. water bath for 20-40 min, and then heating in a 80-90° C. water bath for 10-30 min; the cooling method is cooling in 0-4° C. ice water for 10-30 min.

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