Natural deep eutectic solvent for improving anti-freezing and water-retaining capacity of aquatic products as well as preparation method and application of natural deep eutectic solvent

Abstract

The invention belongs to the technical field of food processing. The invention provides a natural deep eutectic solvent for improving the anti-freezing and water-retaining capacity of aquatic products and a preparation method and application of the natural deep eutectic solvent, the raw materials of the natural deep eutectic solvent comprise proline and glucose, and the molar mass ratio of the proline to the glucose is (1: 1)-(5: 2). Fresh penaeus vannamei meat is rich in moisture and protein, the protein is mainly myofibrillar protein, and the quality of the penaeus vannamei meat is deteriorated due to the fact that protein degradation, oxidation and freezing denaturation are prone to occurring under the commercial freezing condition. The natural deep eutectic solvent provided by the invention has the advantages of natural and non-toxic raw materials, simple components and simple processing mode. After the penaeus vannamei meat is treated by using the natural deep eutectic solvent provided by the invention, the moisture content and the water holding capacity of the penaeus vannamei meat can be remarkably improved, the oxidative degradation degree of protein is reduced, and the sensory quality and the edible value of a product are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and in particular to a natural deep eutectic solvent for improving the antifreeze and water retention capacity of aquatic products, and a preparation method and application thereof. Background Art

[0002] The world is rich in shrimp resources. As one of them, Penaeus vannamei has a good adaptability to temperature, salinity, etc., reproduces quickly, has strong adaptability to the environment, and has a small demand for nutrients in feed. These advantages allow Penaeus vannamei to be intensively bred and farmed, making it an important economic shrimp species for farming. In 2023, the output of Penaeus vannamei will be 2.1 million tons, of which 1.34 million tons will be farmed in seawater and 760,000 tons will be farmed in freshwater. After the shrimp is caught, freezing, preservation, refrigerated storage and transportation are the main processing methods to ensure the quality of shrimp products and extend the shelf life of the products.

[0003] At present, shrimps are mainly frozen and stored without treatment. This storage method seriously damages the quality of shrimps, resulting in a large loss of nutrients and water in shrimp products. Therefore, the field urgently needs a natural deep eutectic solvent that can improve the antifreeze and water retention capacity of white shrimp as an antifreeze and water retention medium to reduce the destruction of nutrients and water loss during cold storage, transportation and processing. Summary of the invention

[0004] The purpose of the present invention is to provide a natural deep eutectic solvent with improved antifreeze and water retention capacity of white shrimp, as well as a preparation method and application thereof, to reduce oxidative degradation and water loss of white shrimp protein during processing, and to improve the sensory quality and edible value of white shrimp products.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a natural deep eutectic solvent for improving the antifreeze and water-retaining capacity of aquatic products. The raw materials of the natural deep eutectic solvent include proline and glucose, and the molar mass ratio of the proline to the glucose is (1:1) to (5:2).

[0007] Preferably, the natural deep eutectic solvent further contains water, and the amount of water used is 10% to 20% of the total mass of proline and glucose.

[0008] Preferably, the proline is L-proline, the glucose is anhydrous glucose, and the glucose is D-(+)-glucose.

[0009] The present invention also provides application of the natural deep eutectic solvent in improving the antifreeze and water-retaining capacity of aquatic products.

[0010] Preferably, the aquatic product includes Penaeus vannamei.

[0011] The present invention also provides a method for preparing the natural deep eutectic solvent, comprising the following steps: mixing proline, glucose and water to obtain the natural deep eutectic solvent.

[0012] Preferably, the mixing method is stirring.

[0013] Preferably, the stirring method is magnetic stirring; the stirring temperature is 50 to 90° C.; and the stirring speed is 100 to 600 rpm.

[0014] The present invention also provides a method for using the natural deep eutectic solvent, comprising the following steps: vacuum heating the aquatic product, applying the natural deep eutectic solvent on the surface of the aquatic product, freezing, and reheating.

[0015] Preferably, the vacuum heating temperature is 60-80°C; the vacuum heating time is 10-20 minutes;

[0016] The freezing temperature is -50 to -30°C; the freezing time is 16 to 26 hours;

[0017] The reheating method is microwave heating; the reheating temperature is 90-110° C.; and the reheating time is 1-5 minutes.

[0018] The beneficial effects of the present invention are:

[0019] The present invention utilizes low-heat, mild and efficient food processing technology, adopts a natural deep eutectic solvent that improves the antifreeze and water retention capacity of white shrimp, and accurately determines the molar mass ratio of the components, so that the texture of white shrimp is improved, the moisture content is higher, the water holding capacity is stronger, the texture is more compact and juicy, and the taste is more elastic and smooth; the water loss of white shrimp is reduced, and the sensory quality is better. Compared with the traditional thermal processing method and the conventional frozen storage method, the technical scheme of the present application can greatly enhance the water retention capacity in the product and reduce the degree of protein oxidation. Therefore, the white shrimp provided by the present invention has high sensory quality and taste flavor, and its moisture content, cooking loss rate, water molecule state, protein microstructure and tissue structure are verified by experiments, so the technical scheme of the present application can be used for white shrimp products that need antifreeze and water retention. In addition, the raw materials of the natural deep eutectic solvent provided by the present invention are natural proteins and sugar substances, which are green and harmless, simple in composition, simple in processing method, low in cost, and mature in product technology and stable in technology, which are suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1It is a comparison diagram of DSC thermogravimetric curves of Example 1, Example 2, Example 3 and Comparative Example 1;

[0021] Figure 2 It is a comparison diagram of the T2 spectra of Example 1, Example 2, Example 3 and Comparative Example 1;

[0022] Figure 3 It is a comparison diagram of polarity characterization of Example 1, Example 2, Example 3 and Comparative Example 1;

[0023] Figure 4 It is a comparison chart of viscosity characterization of Example 1, Example 2, Example 3 and Comparative Example 1;

[0024] Figure 5 It is a comparison chart of the thawing loss rate of white shrimp in Example 4, Comparative Example 2, Comparative Example 3 and Comparative Example 4;

[0025] Figure 6 It is a comparison chart of the water loss rate of white shrimp in Example 4, Comparative Example 2, Comparative Example 3 and Comparative Example 4;

[0026] Figure 7 It is a comparison chart of the centrifugal water holding capacity of Penaeus vannamei of Example 4, Comparative Example 2, Comparative Example 3 and Comparative Example 4;

[0027] Figure 8 It is a comparison diagram of the T2 spectra of whiteleg shrimp of Example 4, Comparative Example 2, Comparative Example 3 and Comparative Example 4;

[0028] Fig. 9 It is a comparison diagram of pseudo-color imaging of white shrimp in Example 4, Comparative Example 2, Comparative Example 3, and Comparative Example 4;

[0029] Fig.10 It is a comparison diagram of the microscopic tissue structure (HE staining) of whiteleg shrimp in Example 4, Comparative Example 2, Comparative Example 3, and Comparative Example 4. DETAILED DESCRIPTION

[0030] The present invention provides a natural deep eutectic solvent for improving the antifreeze and water-retaining capacity of aquatic products. The raw materials of the natural deep eutectic solvent include proline and glucose, and the molar mass ratio of the proline to the glucose is (1:1) to (5:2).

[0031] In the present invention, the molar mass ratio of proline to glucose is preferably 1:1.

[0032] In the present invention, the natural deep eutectic solvent further contains water, and the amount of water is preferably 10% to 20% of the total mass of proline and glucose, and more preferably 15% of the total mass of proline and glucose.

[0033] In the present invention, the proline is preferably L-proline, the glucose is preferably anhydrous glucose, and the glucose is preferably D-(+)-glucose.

[0034] The present invention also provides application of the natural deep eutectic solvent in improving the antifreeze and water-retaining capacity of aquatic products.

[0035] In the present invention, the aquatic product includes Penaeus vannamei.

[0036] The present invention also provides a method for preparing the natural deep eutectic solvent, comprising the following steps: mixing proline, glucose and water to obtain the natural deep eutectic solvent.

[0037] In the present invention, the mixing method is preferably stirring.

[0038] In the present invention, the stirring method is preferably magnetic stirring; the stirring temperature is preferably 50-90°C, more preferably 60-80°C, and further preferably 65°C; the stirring speed is 100-600rpm, more preferably 200-500rpm, and further preferably 300rpm.

[0039] The present invention also provides a method for using the natural deep eutectic solvent, comprising the following steps: vacuum heating the aquatic product, applying the natural deep eutectic solvent on the surface of the aquatic product, freezing, and reheating.

[0040] In the present invention, the temperature of the vacuum heating is preferably 60 to 80° C., more preferably 70° C.; the time of the vacuum heating is preferably 10 to 20 minutes, more preferably 15 minutes;

[0041] The freezing temperature is preferably -50 to -30°C, more preferably -40°C; the freezing time is preferably 16 to 26 hours, more preferably 24 hours;

[0042] The reheating method is preferably microwave heating; the reheating temperature is preferably 90-110° C., more preferably 100° C.; the reheating time is preferably 1-5 min, more preferably 2 min.

[0043] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0044] Example 1

[0045] Add 15% (w / w) distilled water to L-proline and D-(+)-glucose in a molar mass ratio of 2:1, stir evenly, and stir with a magnetic stirrer at 300 rpm at 65°C until a transparent, uniform, viscous liquid is formed.

[0046] Example 2

[0047] Add 15% (w / w) distilled water to L-proline and D-(+)-glucose in a molar mass ratio of 5:2, stir evenly, and stir with a magnetic stirrer at 300 rpm at 65°C until a transparent, uniform, viscous liquid is formed.

[0048] Example 3

[0049] Add 15% (w / w) distilled water to L-proline and D-(+)-glucose in a molar mass ratio of 1:1, stir evenly, and stir with a magnetic stirrer at 300 rpm at 65°C until a transparent, uniform, viscous liquid is formed.

[0050] Example 4

[0051] Fresh whiteleg shrimp were decapped, vacuum-sealed, and steamed at 70°C for 15 min. The shrimps were taken out, the surface moisture was wiped clean, and a natural deep eutectic solvent (Pro:Glc (1:1)) with a molar mass ratio of L-proline and D-(+)-glucose was evenly applied. The shrimps were frozen at -40°C for 24 h, thawed for 10 min, and reheated at 100°C for 2 min.

[0052] Comparative Example 1

[0053] Add 15% (w / w) distilled water to L-proline and D-sorbitol in a molar mass ratio of 1:1, stir evenly, and stir with a magnetic stirrer at 300 rpm at 65°C until a transparent, uniform, viscous liquid is formed.

[0054] Comparative Example 2

[0055] Remove the head, tail and shell of fresh whiteleg shrimp, vacuum seal the shrimp, steam at 70℃ for 15min, take out the shrimp, wipe off the surface moisture, freeze at -40℃ for 24h, thaw for 10min, and reheat at 100℃ for 2min.

[0056] Comparative Example 3

[0057] Remove the head, tail and shell of fresh whiteleg shrimp, seal the shrimp meat as usual, steam at 100℃ for 15min, take out the shrimp meat, wipe off the surface moisture, freeze at -40℃ for 24h, thaw for 10min, and reheat at 100℃ for 2min.

[0058] Comparative Example 4

[0059] Fresh whiteleg shrimps were decapped, headed, tailed and shelled, and the shrimps were sealed in a conventional manner and steamed at 100°C for 15 min. The shrimps were taken out, the surface moisture was wiped clean, Pro:Glc (1:1) was evenly applied, and the shrimps were frozen at -40°C for 24 h, thawed for 10 min, and reheated at 100°C for 2 min.

[0060] Experimental Example 1

[0061] The thermal stability of Example 1, Example 2, Example 3 and Comparative Example 1 at low temperature was measured by differential scanning calorimetry (DSC). About 10 mg of NADES was packaged in a standard aluminum crucible, indium element was used as a standard reference, nitrogen was used as a protective gas, and the temperature was measured at 10 ° C min -1 Heat flow variation of NADES between 25 and -60℃ at a cooling rate of .

[0062] DSC shows the thermal stability of NADES with different components and molar mass ratios at low temperatures. Figure 1 The glass transition temperatures of Example 1, Example 2, Example 3 and Comparative Example 1 are between -56.3 and -46.0°C, while commercial freezing and household storage freezing are usually between -20 and -40°C, so that they all have the potential for cryoprotection in theory, and do not freeze at low temperatures, but only undergo a typical glass transition.

[0063] Experimental Example 2

[0064] Low field nuclear magnetic resonance (LF-NMR) was used to measure the transverse relaxation time (T2) of Example 1, Example 2, Example 3 and Comparative Example 1. The CPMG sequence was sampled with a sampling frequency of 200 kHz, a pre-amplification gear of 2, a cumulative number of 6, and an echo number of 10,000.

[0065] The T2 relaxation time intuitively shows the difficulty of hydrogen protons rotating under the magnetic field radio frequency pulse, thus reflecting the strength of the hydrogen bond binding in the system. The results are as follows Figure 2 As shown, Example 1, Example 2, and Example 3 all have a smaller T2 relaxation time than Comparative Example 1, indicating that the hydrogen bond strength in the system is higher than that in Comparative Example 1, thereby achieving a better effect of retaining water.

[0066] Experimental Example 3

[0067] Nile red staining method was used to characterize the polarity of Example 1, Example 2, Example 3 and Comparative Example 1. 10 mg of Nile red was dissolved in 10 mL of anhydrous ethanol, 50 μL was accurately measured, and 2 mL of Example 1 was added. The other three comparative examples were subjected to the same method, vacuum dried to remove ethanol, and the maximum absorption wavelength (λmax) was recorded by ultraviolet spectrophotometry. The polarity E NR Calculated as 28594 / λmax.

[0068] Nile Red exhibits a greater red shift in the maximum absorption band in more polar solutions. NR Indicates that E NRThe smaller the value, the greater the polarity. The greater the polarity, the stronger the hydrophilicity. Figure 3 As shown, the polarity shows a trend of Example 1≈Example 2>Example 3>Comparative Example 1, and the polarity of sugar-based NADES is larger, while the polarity of alcohol-based NADES is smaller. This indicates that sugar-based NADES has a greater hydrophilicity than alcohol-based NADES, making it easier for NADES to hydrate and thus retain water.

[0069] Experimental Example 4

[0070] The rotational rheometer was used to measure the viscosity of Example 1, Example 2, Example 3 and Comparative Example 1 under varying shear rates. After the instrument was automatically zeroed under no-load conditions, the S63 rotor was selected to measure the viscosity at a continuous speed.

[0071] Viscosity directly reflects the difficulty of molecular movement in the system, which also reflects the strength of hydrogen bonding in the NADES system to a certain extent. Figure 4 At different shear rates, Example 1, Example 2, Example 3 and Comparative Example 1 all exhibit stable apparent viscosity, that is, the viscosity does not change with the change of shear rate, and Figure 4 It is also clearly shown that the viscosities of Example 1, Example 2, and Example 3 are greater than that of Comparative Example 1, and the greater the viscosity, the stronger the hydrogen bonding effect, which makes the hydrogen bonding effect of Example 1, Example 2, and Example 3 higher than that of Comparative Example 1.

[0072] Experimental Example 5

[0073] Remove the head, tail and shell of fresh white shrimp, weigh it, and record it as M1. After cooking Example 4, Comparative Example 2, Comparative Example 3 and Comparative Example 4, wipe off the surface moisture and record the weight as M2. After thawing from frozen storage, the weight is recorded as M3, and the weight after reheating is recorded as M4. Accurately weigh 5.0g, cut it into pieces, put it into a centrifuge tube with two pieces of filter paper, centrifuge it at 4000rpm for 10min, and the weight of the shrimp meat after centrifugation is recorded as M5. The thawing loss rate is calculated by (M2-M3) / M2, the water loss rate is calculated by (M1-M4) / M1, and the water holding capacity is calculated by (5-M5) / 5.

[0074] The thawing loss rate can show the extent of mechanical damage of the muscle protein of Penaeus vannamei by ice crystals during the frozen storage process, the water loss rate shows the water holding capacity of the muscle protein of Penaeus vannamei during the entire processing process, and the water holding capacity clearly shows the water retention capacity of Penaeus vannamei after the entire processing process. The thawing loss rate, water loss rate and water holding capacity of Example 4 and Comparative Examples 2, 3 and 4 are shown in the following table. Figure 5 , 6 , 7. Figure 5As shown in the figure, under the same temperature treatment conditions, the thawing loss rate of Example 4 coated with NADES is significantly lower than that of Comparative Example 2, indicating that the white shrimp treated with Example 4 is less damaged by ice crystals produced by frozen storage, thereby achieving better antifreeze and water retention effects. However, the shrimps in Comparative Examples 3 and 4 have undergone high-temperature cooking in the early stage, and the myofibrillar protein has undergone severe thermal denaturation, and the spatial structure of the protein has changed greatly. The severe denaturation that the protein has undergone before freezing has limited the mechanical damage of the protein to the protein caused by the growth of ice crystals during subsequent freezing. However, the thawing loss rate of Comparative Example 4 coated with NADES is still significantly lower than that of Comparative Example 3, which also shows that NADES can effectively protect the shrimp protein from low temperature damage to a certain extent. Figure 6 It shows that the water loss rate of Example 4 in the entire processing technology is significantly lower than that of Comparative Examples 2, 3 and 4. Figure 7 It shows that the water holding capacity of Comparative Examples 2, 3 and 4 is lower than that of Example 4, while it shows that after treatment with Example 4, the water holding capacity of white shrimp can be better improved and its water loss can be reduced.

[0075] Experimental Example 6

[0076] The transverse relaxation time (T2) of Example 4, Comparative Example 2, Comparative Example 3 and Comparative Example 4 was measured by low-field nuclear magnetic resonance (LF-NMR). The CPMG sequence was sampled with a sampling frequency of 200 kHz, a pre-release gear of 2, a cumulative number of 6, and an echo number of 10000. The nuclear magnetic imaging software was called to analyze the moisture distribution and state. After the prescan, the scout located the sample position, scanned the image, and used pseudo-color processing.

[0077] The T2 spectrum shows the difference in the ratio of non-flowing water between Example 4 and Comparative Example 2, Comparative Example 3, and Comparative Example 4. The pseudo-color imaging diagram intuitively shows the water distribution and state of the white shrimp. The results are as follows: Figure 8 , 9 As shown. Figure 8 As shown, the T2 peak of Example 4 is higher than that of Comparative Examples 2, 3 and 4, indicating that Example 4 has a higher proportion of immobile water, and less water is converted and migrated from immobile water to free water, thereby reducing the water loss of white shrimp. Fig. 9 ) The darker the dark red part, the higher the water content of the part, and the harder it is for the water to be lost. The figure also shows that the dark red part of Example 4 has a larger area, while Comparative Example 2, Comparative Example 3, and Comparative Example 4 have a larger area of ​​dark blue parts, which represents that more non-flowing water is transformed and migrated to free water, verifying the conclusion of the T2 spectrum.

[0078] Experimental Example 7

[0079] Hematoxylin-eosin staining was used to analyze the microstructure of Example 4 and Comparative Examples 2, 3, and 4. The second segment of the shrimp sample was cut into small pieces of 0.2 cm × 0.2 cm × 0.2 cm, and fixed with 4% paraformaldehyde solution overnight. After gradient alcohol dehydration, the sample was embedded in paraffin, and after dewaxing and washing, HE staining was performed and observed at 200 times.

[0080] HE staining can intuitively show the microscopic tissue results of Example 4 and Comparative Examples 2, 3 and 4, mainly the bending and breaking of myofibrillar protein and the size of the gaps. The results are as follows: Fig.10 As shown. The myofibrillar proteins in Example 4 are neat, coherent and closely arranged, with smaller gaps. However, due to the loss of NADES cryoprotection, the ice crystals in Comparative Example 4 are damaged to a certain extent, and the pores are larger than those in Example 4. Comparative Examples 3 and 4 are more severely thermally denatured, resulting in the phenomenon of myofibrils being fragmented, and the muscle tissue of the white shrimp is destroyed. The deterioration of the tissue structure causes a large amount of water loss.

[0081] It can be seen from the above embodiments that the present invention provides a natural deep eutectic solvent for improving the antifreeze and water-retaining capacity of aquatic products, and a preparation method and application thereof. The raw materials of the natural deep eutectic solvent include proline and glucose, and the molar mass ratio of proline and glucose is (1:1) to (5:2). Fresh white shrimp meat contains rich water and protein, of which myofibrillar protein is the main protein. Under commercial freezing conditions, protein degradation, oxidation and freezing denaturation are prone to occur, resulting in deterioration of the quality of the shrimp meat product. The raw materials of the natural deep eutectic solvent provided by the present invention are natural and non-toxic, with simple ingredients and simple processing methods. After the white shrimp meat is treated with the natural deep eutectic solvent provided by the present invention, the moisture content and water holding capacity of the white shrimp meat can be significantly improved, the degree of protein oxidation degradation can be reduced, and the sensory quality and edible value of the product can be improved.

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A natural deep eutectic solvent for improving the antifreeze and water retention capacity of aquatic products, characterized in that: The raw materials of the natural deep eutectic solvent include proline and glucose, and the molar mass ratio of the proline to the glucose is (1:1) to (5:2).

2. The natural deep eutectic solvent according to claim 1, characterized in that: The natural deep eutectic solvent also contains water, and the amount of the water is 10% to 20% of the total mass of proline and glucose.

3. The natural deep eutectic solvent according to claim 1 or 2, characterized in that: The proline is L-proline, the glucose is anhydrous glucose, and the glucose is D-(+)-glucose.

4. Use of the natural deep eutectic solvent according to any one of claims 1 to 3 in improving the antifreeze and water retention capacity of aquatic products.

5. The use according to claim 4, characterized in that: The aquatic product includes whiteleg shrimp.

6. A method for preparing the natural deep eutectic solvent according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: mixing proline, glucose and water to obtain a natural deep eutectic solvent.

7. The preparation method according to claim 6, characterized in that: The mixing method is stirring.

8. The preparation method according to claim 7, characterized in that: The stirring method is magnetic stirring; the stirring temperature is 50-90° C.; and the stirring speed is 100-600 rpm.

9. A method for using the natural deep eutectic solvent according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: after vacuum heating treatment of the aquatic product, applying a natural deep eutectic solvent on the surface of the aquatic product, freezing, and reheating.

10. The method of use according to claim 9, characterized in that: The vacuum heating temperature is 60 to 80°C; the vacuum heating time is 10 to 20 minutes; The freezing temperature is -50 to -30°C; the freezing time is 16 to 26 hours; The reheating method is microwave heating; the reheating temperature is 90-110° C.; and the reheating time is 1-5 minutes.

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