Method for improving content of flavor dipeptide in salted fish

Abstract

The invention provides a method for improving the content of flavor dipeptide in salted fish. The method comprises the following steps: pretreating fish to obtain fish blocks; uniformly smearing the fish blocks with table salt to obtain the smeared fish blocks; placing the coated fish blocks in a vacuum package, and vacuumizing to obtain vacuum-packaged fish blocks; performing ultrahigh-pressure pretreatment on the fish blocks subjected to vacuum packaging to obtain the fish blocks subjected to ultrahigh-pressure treatment; and pickling the fish blocks subjected to ultrahigh pressure treatment for natural fermentation to obtain the pickled fish blocks with improved flavor dipeptide content. According to the method disclosed by the invention, the abundance of microorganisms during pickling is adjusted by combining ultrahigh-pressure pretreatment with natural fermentation, so that the content of the flavor dipeptides Val-Ile, Val-Leu, Pro-Lys, Asp-Val, Ile-Glu, Lys-Gly and Ser-Phe in the pickled fish blocks is improved, and finally, the purpose of improving the taste of the pickled fish is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of aquatic product processing, and in particular to a method for improving the content of flavor dipeptides in pickled fish. Background Art

[0002] Pickling is an important way of processing fish, the purpose of which is to extend the shelf life and derive products with unique flavor and taste. At the same time, microorganisms and endogenous enzyme micro-fermentation during pickling also provide an effective way to form the unique flavor and taste of pickled products. Traditional pickled fish uses natural osmosis to infiltrate salt or other pickling liquid into the product to achieve the effect of extending the shelf life. Because it is necessary to ensure that the product does not deteriorate during the pickling process, a higher salt concentration is usually used for pickling (usually 5-10%), which makes the pickled product too salty and requires multiple rehydration and thorough washing before it can be processed and eaten. High-salt environment is also not conducive to the hydrolysis of microorganisms and enzymes, resulting in poor taste of pickled fish. At the same time, excessive intake of products with too high salt content will increase the risk of cardiovascular disease. Therefore, how to reduce the salt content to increase the flavor and health attributes while ensuring the food safety of the product is of great significance to both manufacturers and consumers.

[0003] Ultrahigh pressure, which uses water or other liquids as pressure transmission media to apply pressure stress to food, is a new type of non-thermal sterilization technology and a technology that promotes salt pickling penetration. Pressure-mediated destruction of muscle fiber structure will increase the penetration rate of salt between tissues. Therefore, studies have shown that ultrahigh pressure technology can be used to shorten the pickling time and extend the shelf life of pickled products. These processing pressures are usually within 300-700 MPa, and this pressure range has a significant killing effect on microorganisms in food. In addition, studies have shown that pressure treatment between 250-300 MPa is the pressure for myofibrillar protein denaturation. The myofibrillar protein denaturation and muscle tissue structure changes caused by pressure will make meat products white. For fish meat, whitening often means ripening or deterioration, and consumers often cannot accept such products.

[0004] Therefore, it is of great significance to develop a new technology to solve the shortcomings of pickled fish products such as poor quality, high salt content, and uneven pickling, while effectively avoiding the ripening phenomenon caused by ultra-high pressure. Summary of the invention

[0005] The present disclosure provides a method for improving the content of flavor dipeptides in pickled fish by regulating the abundance of microorganisms during pickling through ultra-high pressure pretreatment pickling combined with natural fermentation, so as to at least solve the above technical problems existing in the prior art.

[0006] According to a first aspect of the present disclosure, there is provided a method for improving the content of flavor dipeptides in pickled fish, comprising the following steps: S1, pre-processing the fish to obtain fish pieces; S2, evenly coating the fish pieces with salt to obtain coated fish pieces; S3, placing the smeared fish pieces in a vacuum package and evacuating the package to obtain vacuum-packaged fish pieces; S4, subjecting the vacuum-packed fish pieces to ultra-high pressure pretreatment to obtain ultra-high pressure treated fish pieces; wherein the ultra-high pressure pretreatment pressure is 50-250 MPa, and the time is 5-15 min; S5. marinating the fish pieces after the ultrahigh pressure treatment and performing natural fermentation to obtain marinated fish pieces with improved content of flavor dipeptides.

[0007] In one embodiment, the flavor dipeptide includes Val-Ile, Val-Leu, Pro-Lys, Asp-Val, Ile-Glu, Lys-Gly and Ser-Phe. Specifically, the improvement in the content of the flavor dipeptide is reflected in the reduction of bitter dipeptides Val-Ile, Val-Leu and Pro-Lys, the increase of umami dipeptides Ile-Glu, Lys-Gly and Ser-Phe, and the increase of the content of sour dipeptide Asp-Val.

[0008] In one embodiment, the content of the flavor dipeptide is improved by regulating the abundance of microorganisms during pickling, wherein the microorganisms include Macrococcus caseolyticus , Carnobacterium divergens , Vagococcus riverine , Psychrobacter maritimus , Psychrobacter urativorans and Soonwooa from Buenaventura .

[0009] In one embodiment, the pretreatment in step S1 includes descaling, deveining, deboning, cleaning and cutting.

[0010] In one embodiment, the amount of salt added in step S2 is 1.5-2.5% by mass.

[0011] In a preferred embodiment, the added amount of the salt is 2% by mass.

[0012] In one embodiment, the vacuuming time in step S3 is 30-40 s, and the vacuum packaging state is maintained for 30-60 min.

[0013] In a preferred embodiment, the vacuuming time is 35 s, and the vacuum packaging state is maintained for 60 min.

[0014] In a preferred embodiment, the ultrahigh pressure pretreatment in step S4 is performed at a pressure of 100 MPa for 10 min.

[0015] In one embodiment, the pickling method in step S5 is dry pickling, the pickling temperature is 4° C., and the time is 36-52 hours.

[0016] In a preferred embodiment, the pickling temperature is 4° C. and the time is 36 h.

[0017] According to a second aspect of the present disclosure, provided is a pickled fish block prepared according to the above method.

[0018] According to an implementable embodiment of the present disclosure, at least the following beneficial effects are achieved: (1) The present invention regulates the microorganisms in pickling by combining ultra-high pressure pretreatment with natural fermentation Macrococci caseolytic , Carnobacterium divergens , Vagococcus fluvialis , Psychrobacter maritime , Psychrobacter urativorans and Soonwooa buanensis The abundance of flavor dipeptides Val-Ile, Val-Leu, Pro-Lys, Asp-Val, Ile-Glu, Lys-Gly and Ser-Phe in pickled fish blocks can be improved, thereby achieving the purpose of improving the taste of pickled fish.

[0019] (2) The ultra-high pressure pretreatment disclosed in the present invention is a short-time pressure treatment, which avoids excessive damage to the fish tissue structure caused by long-time pressure treatment. At the same time, the natural fermentation is a dry-salted natural fermentation, which makes the small molecular compounds produced during the salting process more effectively intercepted, and reduces the amount of salt added while ensuring the taste.

[0020] (3) The ultra-high pressure pretreatment disclosed in the present invention adopts ultra-high pressure within 250 MPa, which not only reasonably uses ultra-high pressure to promote pickling and has the advantage of regulating microorganisms, but also avoids the ripening phenomenon caused by pressure, making the product more in line with actual needs.

[0021] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. DETAILED DESCRIPTION

[0022] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0023] Example 1 In this example, Culter alba ( Alburn knife ) was used as an example to marinate fish chunks. The specific process is as follows: (1) After descaling, removing internal organs and bones of the fish, washing and cutting into pieces, a fish fillet is obtained; (2) adding salt in an amount of 2% by mass to evenly coat the fish pieces to obtain coated fish pieces; (3) placing the coated fish fillet in a vacuum packaging bag and performing vacuum extraction for 35 seconds and maintaining the vacuum packaging state for 60 minutes to obtain a vacuum-packed fish fillet; (4) placing the vacuum-packed fish pieces in an ultra-high pressure generating device for ultra-high pressure treatment at a pressure of 100 MPa for 10 min to obtain ultra-high pressure treated fish pieces; (5) The fish pieces after the ultrahigh pressure treatment are taken out and placed in a 4°C environment for marinating for 36 hours for natural fermentation, wherein the marinating is dry marinating to obtain marinated fish pieces.

[0024] Example 2 In this example, Culter alba ( Alburn knife ) was used as an example to marinate fish chunks. The specific process is as follows: (1) After descaling, removing internal organs and bones of the fish, washing, and cutting into pieces, a fish fillet is obtained; (2) adding salt in an amount of 2% by mass to evenly coat the fish pieces to obtain coated fish pieces; (3) placing the coated fish fillet in a vacuum packaging bag and performing vacuum extraction for 35 seconds and maintaining the vacuum packaging state for 60 minutes to obtain a vacuum-packed fish fillet; (4) placing the vacuum-packed fish pieces in an ultra-high pressure generating device for ultra-high pressure treatment at a pressure of 250 MPa for 10 min to obtain ultra-high pressure treated fish pieces; (5) The fish pieces after the ultrahigh pressure treatment are taken out and placed in a 4°C environment for marinating for 36 hours for natural fermentation, wherein the marinating is dry marinating to obtain marinated fish pieces.

[0025] Comparative Example In this comparative example, Culter alba ( Alburn knife) was used as an example to marinate fish chunks. The specific process is as follows: (1) After descaling, removing internal organs and bones of the fish, washing and cutting into pieces, a fish fillet is obtained; (2) adding salt in an amount of 9% by mass to evenly coat the fish pieces to obtain coated fish pieces; (3) placing the coated fish fillet in a vacuum packaging bag and performing vacuum extraction for 35 seconds and maintaining the vacuum packaging state for 60 minutes to obtain a vacuum-packed fish fillet; (4) taking out the vacuum-packed fish pieces and placing them in a 4°C environment for marinating for 36 hours for natural fermentation, wherein the marinating is dry marinating, to obtain marinated fish pieces.

[0026] Test example 1. Detection of the content of flavor dipeptides in pickled fish cubes treated with different pressures The peak areas of the flavor dipeptides Val-Ile, Val-Leu, Pro-Lys, Asp-Val, Ile-Glu, Lys-Gly and Ser-Phe in the pickled fish obtained in Examples 1 and 2 and the comparative example were detected. The specific method was: extracting with 70% methanol water internal standard extract to obtain an extract; detecting the extract by ultra-high performance liquid chromatography and tandem mass spectrometry, processing the mass spectrometry data by software Analyst 1.6.3, obtaining the peak areas of 7 flavor dipeptides, and further obtaining the contents of Val-Ile, Val-Leu, Pro-Lys, Asp-Val, Ile-Glu, Lys-Gly and Ser-Phe.

[0027] The results are shown in Table 1. The results show that ultrahigh pressure treatment (Example 1) can reduce the accumulation of bitter dipeptides (Val-Ile, Val-Leu and Pro-Lys) in pickled fish chunks, increase the enrichment of umami dipeptides (Ile-Glu, Lys-Gly and Ser-Phe) in pickled fish chunks, and increase the sour dipeptide (Asp-Val) to neutralize the bitterness, thereby achieving a synergistic flavor enhancement effect.

[0028] Table 1 Contents of flavor dipeptides in pickled fish cubes treated with different pressures

[0029] The taste description comes from the experimental data statistics of related peptides in http: / / tastepeptides-meta.com.

[0030] 2. Correlation analysis between 7 flavor dipeptides and 6 microorganisms in pickled fish The correlation between the seven flavor dipeptides and the six microorganisms in the pickled fish obtained in Examples 1 and 2 and the comparative example was analyzed using the official website of Major Biotechnology (https: / / cloud.majorbio.com), and the results were obtained. p value and R value.

[0031] p The results of the values ​​are shown in Table 2. The results show that the seven flavor dipeptides Macrococcus caseolyticus , Carnobacterium divergens , Vagococcus fluvialis , Psychrobacter maritimus , Psychrobacter urativorans and Soonwooa buanensis There is a significant correlation ( P <0.05) Table 2 Flavor dipeptides and six microorganisms p value

[0032] P When the value is <0.05, it is considered that the dipeptide and bacteria have statistical significance and a significant correlation exists.

[0033] The results of R values ​​are shown in Table 3 , which show that different types of microorganisms contribute differently to the formation of different flavor dipeptides, e.g. Carnobacterium divergens There is a completely positive correlation with the formation of Lys-Gly (umami taste) and a highly negative correlation with the formation of Pro-Lys (bitter taste).

[0034] Table 3 R values ​​of flavor dipeptides and six microorganisms

[0035] The R value represents the statistical index of the correlation between flavor dipeptides and the six microorganisms, and the value range is between -1 and 1, where 0 means no correlation, 1 means a completely positive correlation, and -1 means a completely negative correlation.

[0036] 3. Abundance detection of six microorganisms in pickled fish The abundance of six kinds of microorganisms (the taxonomic pedigrees are shown in Table 4) in the pickled fish blocks obtained in Examples 1, 2 and the comparative example was detected. The specific method was as follows: the total genomic DNA of the microorganisms in the pickled fish blocks was extracted using the EZNA® Soil DNA Kit DNA extraction kit (Omega, USA), and the 16S rRNA gene V3-V4 variable region was PCR amplified using the upstream primer 338F and the downstream primer 806R carrying the Barcode sequence using the DNA as a template. Sequencing was performed using the Miseq PE300 / NovaSeq PE250 platform of Illumina Company, and the abundance of the six kinds of microorganisms in the pickled fish blocks obtained in Examples 1, 2 and the comparative example was counted.

[0037] The results are shown in Table 5 , which indicate that pressure can regulate the abundance of these microorganisms in fish marination, for example, high pressure (250 MPa) promoted Macrococcus Caseolyticus growth, inhibit Carnobacterium diverging The growth of Macrococcus caseolyticus , Carnobacterium diverging and Vagococcus fluvialis growth and inhibit Psychrobacter maritime , Psychrobacter urativorans and Soonwooa buanensis Growth 。

[0038] Table 4 Taxonomic spectrum of six microorganisms

[0039] Table 5 Abundance of six microorganisms in different pressure-cured fish cubes

[0040] As described above, the present invention improves the content of flavor dipeptides in pickled fish by regulating the abundance of microorganisms during pickling through ultrahigh pressure pretreatment combined with natural fermentation, thereby achieving the purpose of improving the taste of pickled fish.

[0041] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of this disclosure can be achieved, and this document is not limited here.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0043] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for improving the content of flavor dipeptides in pickled fish, characterized in that: The method comprises the following steps: S1, pre-processing the fish to obtain fish pieces; S2, using salt to evenly apply the fish pieces to obtain the applied fish pieces; wherein the amount of salt added is 2% by mass percentage; S3, placing the smeared fish pieces in a vacuum package and evacuating the package to obtain vacuum-packaged fish pieces; S4, subjecting the vacuum-packed fish pieces to ultra-high pressure pretreatment to obtain ultra-high pressure treated fish pieces; wherein the ultra-high pressure pretreatment pressure is 100-250 MPa, and the time is 10 min; S5, pickling the fish pieces after ultrahigh pressure treatment and performing natural fermentation to obtain pickled fish pieces with improved content of flavor dipeptides; wherein the improved content of flavor dipeptides is achieved by regulating the abundance of microorganisms during pickling, and the microorganisms include Macrococcus caseolyticus , Carnobacterium divergens , Vagococcus fluvialis , Psychrobacter maritimus , Psychrobacter urativorans and Soonwooa buanensis .

2. The method according to claim 1, characterized in that The flavor dipeptides include Val-Ile, Val-Leu, Pro-Lys, Asp-Val, Ile-Glu, Lys-Gly and Ser-Phe; the improvement in the content of the flavor dipeptides is reflected in reducing the content of the bitter dipeptides Val-Ile, Val-Leu and Pro-Lys, increasing the umami dipeptides Ile-Glu, Lys-Gly and Ser-Phe, and increasing the content of the sour dipeptide Asp-Val.

3. The method according to claim 1, characterized in that The ultra-high pressure pretreatment in step S4 is performed at a pressure of 100 MPa for 10 min.

4. The method according to claim 1, characterized in that The pickling temperature in step S5 is 4° C. and the pickling time is 36 h.

5. The method according to claim 1, characterized in that The vacuuming time in step S3 is 35 s, and the vacuum packaging state is maintained for 60 min.

6. The method according to claim 1, characterized in that The pretreatment in step S1 includes descaling, de-eviscerating, deboning, washing and cutting into pieces.

7. Provide a pickled fish block prepared by the method according to any one of claims 1 to 6.

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