Preservation method of prefabricated shrimps

Abstract

The invention provides a preservation method of prefabricated shrimps, and belongs to the technical field of aquatic product processing, and the preservation method comprises the following steps: taking shrimp meat, cleaning, pickling and preserving the shrimp meat, and performing pulsed electric field treatment and vacuum slow cooking to obtain the prefabricated shrimps. A pulsed electric field and vacuum slow cooking coupling technology is adopted, and electroporation generated by the pulsed electric field is utilized to promote pickling fresh-keeping liquid to quickly permeate into shrimp meat tissues, so that heat conduction in the vacuum slow cooking process is facilitated, and shrimp meat curing is accelerated; in addition, clove essential oil, sweet leafy vegetable polyphenol and pullulan are compounded for use, a gel network structure of the pullulan and a protective hydration layer of polyphenol-shrimp meat myofibrillar protein can maintain the water holding performance of shrimp muscles, and water loss is reduced; meanwhile, clove essential oil and stevia rebaudian polyphenol can inhibit reproduction of harmful microorganisms through antibacterial and antioxidant effects, the freshness of the prefabricated shrimps is guaranteed, and a new thought is provided for research and development of high-added-value aquatic products.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquatic product processing, and particularly relates to a fresh-keeping method for prefabricated shrimps. Background Art

[0002] Shrimps are deeply favored by consumers because of their delicious meat, rich in amino acids, calcium and magnesium elements required by the human body. Most of the shrimp aquatic products in China are mainly sold fresh. Since shrimps are rich in high protein, high moisture and glycogen content, they provide nutrients for the growth of microorganisms, their own enzyme activity causes autolysis, and exogenous bacteria are easy to reproduce, resulting in easy oxidation and spoilage, juice loss and accelerated deterioration during storage. Therefore, with the expansion of the shrimp consumer group, it is very necessary to develop a prefabricated shrimp with good flavor quality and high nutritional value. Prefabricated shrimps are ready-to-eat or semi-finished foods made from shrimps through processing, including frozen fresh shrimps, flavored canned foods, leisure snacks and nutritional preparations, etc., aiming to solve the problems of inconvenient eating and short shelf life of traditional shrimps. At present, shrimp aquatic products are usually sterilized and enzyme-inactivated by high-temperature heating, which to a certain extent destroys the muscle protein structure and many nutrients of shrimps. At the same time, excessive heat treatment will also cause shrimp muscle hardening and protein and lipid oxidation. Appropriate low-temperature and short-time heat treatment can reduce the water loss in the muscle to a certain extent and effectively maintain the flavor and texture characteristics of the product. Therefore, it is urgent to explore a more efficient preparation and fresh-keeping method for prefabricated shrimps, which can promote the accelerated development of shrimps towards ready-to-eat and functional directions. Summary of the Invention

[0003] Technical problems to be solved: Aiming at the above technical problems, the purpose of the present invention is to provide a fresh-keeping method for prefabricated shrimps, and the steps are as follows: taking the meat of shrimps for cleaning, pickling the shrimp meat and subjecting it to pulsed electric field treatment, and vacuum slow cooking to obtain prefabricated shrimps, belonging to the technical field of aquatic product processing. The present invention adopts the coupling technology of pulsed electric field and vacuum slow cooking, and uses the electroporation generated by the pulsed electric field to promote the rapid penetration of the pickling fresh-keeping liquid into the shrimp meat tissue, which is beneficial to accelerating the ripening of shrimp meat during the vacuum slow cooking process due to heat conduction; in addition, the compound use of clove essential oil, stevia polyphenol and pullulan polysaccharide is adopted. The gel network structure of pullulan polysaccharide and the protective hydration layer of polyphenol-shrimp myofibrillar protein can maintain the water-holding performance of shrimp muscle and reduce water loss; at the same time, clove essential oil and stevia polyphenol can inhibit the reproduction of harmful microorganisms through antibacterial and antioxidant effects, ensuring the freshness of prefabricated shrimps and providing new ideas for the research and development of high-value-added aquatic products.

[0004] Technical solution: A fresh-keeping method for prefabricated shrimps, adopting the coupling technology of vacuum slow cooking and pulsed electric field, specifically includes the following steps: S1. Select fresh and intact shrimps, clean and remove impurities to obtain fresh shrimp meat; S2. Immerse the fresh shrimp meat in the pickling fresh-keeping liquid, and obtain pretreated shrimp meat through pulsed electric field treatment; S3. The pre-processed shrimp meat is packaged and then slowly cooked under vacuum, and then rapidly cooled to obtain the pre-processed shrimp. Furthermore, in step S2, the material-liquid ratio of the fresh shrimp meat to the pickling liquid is 1:(2.5-5). Furthermore, the pickling and preservative liquid in step S2 is prepared by adding water to the pickling material and the preservative. Furthermore, the marinade includes the following components: 5-10% salt, 5-7.5% white sugar, 3-5% soy sauce, 1.5-3% star anise, 0.1-1% cooking wine, and 0.2-0.8% monosodium glutamate, calculated based on the weight of fresh shrimp meat. Furthermore, the preservative comprises the following components: 0.2-1.5% of clove essential oil, 0.5-1% of stevia polyphenols, 1.5-2.5% of pullulan, and the balance being water, calculated based on the weight of the pickling preservative liquid. Furthermore, the conditions for the pulse electric field treatment in step S2 are electric field intensity 1-3 kV / cm, electric field frequency 500-750 Hz, and treatment time 2.5-5 min. Furthermore, the vacuum cooking conditions in step S3 are a cooking temperature of 60-80° C. and a cooking time of 5-15 minutes. Prefabricated shrimp prepared by any of the above methods. Beneficial effects: 1. The present invention utilizes a pulsed electric field and vacuum slow cooking coupling technology to prepare pre-cooked shrimp. The pulsed electric field utilizes a high-intensity electric field to induce electroporation in the shrimp meat tissue, significantly improving its permeability, facilitating the penetration of the marinade into the shrimp meat, accelerating the migration and redistribution of moisture and flavoring substances, and also destroying the integrity of the cell membranes of harmful microorganisms, achieving a certain degree of sterilization effect. In addition, the electroporation effect of the pulsed electric field can promote heat transfer during the vacuum slow cooking process, uniformly heating the shrimp meat, improving the shrimp meat's cooking efficiency and reducing the nutritional loss of the shrimp meat. At the same time, it can further improve the sterilization efficiency, providing a highly effective solution for improving the texture and preserving the nutrition of pre-cooked shrimp. 2. The preservative ingredients of the present invention are a combination of clove essential oil, beet polyphenols and pullulan. On the one hand, the targeted membrane destruction of gram-negative bacteria by clove essential oil and the intracellular free radical scavenging effect of stevia polyphenols complement each other, and they act synergistically in the preservation of pre-prepared shrimp. In addition, pullulan forms a three-dimensional network hydrogel through β-1,6 glycosidic bonds, which limits the contact of microorganisms with the matrix and prolongs the antibacterial effect time. On the other hand, the protective hydration layer formed by the hydrophobic interaction between the pullulan gel network, polyphenols and shrimp myofibrillar proteins constitutes a multi-scale water retention system, which improves the water holding capacity of shrimp muscles and improves the uniformity of water distribution in the interstitial spaces of muscle fibers, thereby reducing juice exudation. DETAILED DESCRIPTION The present invention will be further described below in conjunction with embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments: Embodiment 1 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and wash and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, then weigh 7.5 g of clove essential oil, 7.5 g of stevia leaf polyphenol, 22.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling preservation solution; S3. Immerse 500 g of fresh shrimp meat in 1.5 L of the pickling preservation solution, and perform pulsed electric field treatment at 1.5 kV / cm and 600 Hz for 3 min to obtain pretreated shrimp meat; S4. After packaging the pretreated shrimp meat, vacuum slow cook it at 70 °C for 10 min, and then quickly cool it to obtain prefabricated shrimp. Embodiment 2 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and wash and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, then weigh 10 g of clove essential oil, 10 g of stevia leaf polyphenol, 30 g of pullulan polysaccharide, mix them evenly and add water to make a pickling preservation solution; S3. Immerse 500 g of fresh shrimp meat in 2.0 L of the pickling preservation solution, and perform pulsed electric field treatment at 1.5 kV / cm and 600 Hz for 4 min to obtain pretreated shrimp meat; S4. After packaging the pretreated shrimp meat, vacuum slow cook it at 70 °C for 10 min, and then quickly cool it to obtain prefabricated shrimp. Embodiment 3 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and wash and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, then weigh 12.5 g of clove essential oil, 12.5 g of stevia leaf polyphenol, 37.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling preservation solution; S3. Immerse 500 g of fresh shrimp meat in 2.5 L of the pickling preservation solution, and perform pulsed electric field treatment at 1.5 kV / cm and 600 Hz for 3 min to obtain pretreated shrimp meat; S4. After packaging the pre-treated shrimp meat, it is vacuum sous vide at 70 °C for 10 min and then rapidly cooled to obtain the prefabricated shrimp. Example 4 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and wash and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, then weigh 15 g of clove essential oil, 15 g of stevia leaf polyphenol, 37.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling and preservation solution; S3. Immerse 500 g of fresh shrimp meat in 1.5 L of the pickling and preservation solution, and perform pulsed electric field treatment at 1.5 kV / cm and 600 Hz for 3 min to obtain the pre-treated shrimp meat; S4. After packaging the pre-treated shrimp meat, it is vacuum sous vide at 70 °C for 10 min and then rapidly cooled to obtain the prefabricated shrimp. Example 5 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and wash and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, then weigh 7.5 g of clove essential oil, 15 g of stevia leaf polyphenol, 22.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling and preservation solution; S3. Immerse 500 g of fresh shrimp meat in 1.5 L of the pickling and preservation solution, and perform pulsed electric field treatment at 1.5 kV / cm and 600 Hz for 4 min to obtain the pre-treated shrimp meat; S4. After packaging the pre-treated shrimp meat, it is vacuum sous vide at 70 °C for 10 min and then rapidly cooled to obtain the prefabricated shrimp. Example 6 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and wash and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, then weigh 7.5 g of clove essential oil, 7.5 g of stevia leaf polyphenol, 22.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling and preservation solution; S3. Immerse 500 g of fresh shrimp meat in 1.5 L of the pickling and preservation solution, and perform pulsed electric field treatment at 2.0 kV / cm and 600 Hz for 3 min to obtain the pre-treated shrimp meat; S4. After packaging the pre-treated shrimp meat, it is vacuum sous vide at 70 °C for 10 min and then rapidly cooled to obtain the prefabricated shrimp. Example 7 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and clean and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, and then weigh 7.5 g of clove essential oil, 7.5 g of stevia leaf polyphenols, 22.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling and preservation solution; S3. Immerse 500 g of fresh shrimp meat in 1.5 L of the pickling and preservation solution, and perform pulsed electric field treatment at 1.5 kV / cm and 750 Hz for 4 min to obtain pretreated shrimp meat; S4. After packaging the pretreated shrimp meat, vacuum-slow cook it at 70 °C for 10 min, and then quickly cool it to obtain prefabricated shrimp. Example 8 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and clean and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, and then weigh 7.5 g of clove essential oil, 7.5 g of stevia leaf polyphenols, 22.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling and preservation solution; S3. Immerse 500 g of fresh shrimp meat in 1.5 L of the pickling and preservation solution, and perform pulsed electric field treatment at 1.5 kV / cm and 600 Hz for 3 min to obtain pretreated shrimp meat; S4. After packaging the pretreated shrimp meat, vacuum-slow cook it at 80 °C for 10 min, and then quickly cool it to obtain prefabricated shrimp. Example 9 A preservation method for prefabricated shrimp, comprising the following steps: S1. Select fresh and intact shrimp, shell them to obtain the meat, and clean and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, and then weigh 7.5 g of clove essential oil, 7.5 g of stevia leaf polyphenols, 22.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling and preservation solution; S3. Immerse 500 g of fresh shrimp meat in 1.5 L of the pickling and preservation solution, and perform pulsed electric field treatment at 1.5 kV / cm and 600 Hz for 4 min to obtain pretreated shrimp meat; S4. After packaging the pretreated shrimp meat, vacuum-slow cook it at 70 °C for 10 min, and then quickly cool it to obtain prefabricated shrimp. Comparative Example 1 The difference between this comparative example and Example 5 is that pulsed electric fields are not used. A preservation method for prefabricated shrimps, comprising the following steps: S1. Select fresh and intact shrimps, shell them to obtain the meat, and clean and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, then weigh 7.5 g of clove essential oil, 15 g of stevia leaf polyphenol, 22.5 g of pullulan polysaccharide, mix them evenly and add water to make a pickling and preservation solution; S3. Soak 500 g of fresh shrimp meat in the pickling and preservation solution for 20 min to obtain pretreated shrimp meat; S4. After packaging the pretreated shrimp meat, vacuum-slow cook it at 70 °C for 10 min, and then quickly cool it to obtain prefabricated shrimps. Comparative Example 2 The difference between this comparative example and Example 5 is that clove essential oil, stevia leaf polyphenol, and pullulan polysaccharide are not added. A preservation method for prefabricated shrimps, comprising the following steps: S1. Select fresh and intact shrimps, shell them to obtain the meat, and clean and remove impurities to obtain fresh shrimp meat; S2. Weigh 40 g of table salt, 30 g of granulated sugar, 15 g of soy sauce, 10 g of star anise, 5 g of cooking wine, 3 g of monosodium glutamate, mix them evenly and add water to make a pickling solution; S3. Soak 500 g of fresh shrimp meat in 1.5 L of the pickling solution, and perform pulsed electric field treatment at 1.5 kV / cm and 600 Hz for 4 min to obtain pretreated shrimp meat; S4. After packaging the pretreated shrimp meat, vacuum-slow cook it at 70 °C for 10 min, and then quickly cool it to obtain prefabricated shrimps. Performance test (1) Cooking loss rate For the prefabricated shrimps in vacuum packaging, denoted as M1, after opening the vacuum bag after preparation, wipe off the moisture on the surface of the shrimp meat and in the vacuum bag with a gauze, and then weigh it (including the semi-shelled scallops and the vacuum bag), denoted as M2; calculate its cooking loss rate, cooking loss rate (%) = (M1 - M2) / M1 × 100%. (2) Sensory evaluation Select 10 people (5 males and 5 females) to form an evaluation group, and score the juice color, odor, juiciness, elasticity, hardness, and overall acceptability of the prefabricated shrimps according to Table 1, where the higher the score, the better the sensory quality of the prefabricated shrimps. Table 1 Sensory scoring criteria for prefabricated shrimps Table 2 Cooking loss rate and sensory evaluation of Examples 1-9, Comparative Example 1 and Comparative Example 2 As can be seen from Table 2, the cooking loss rate and sensory evaluation of Examples 1-9 are superior to those of Comparative Example 1 and Comparative Example 2, indicating that the electroporation effect generated by pulsed electric fields during the preparation of prefabricated shrimp can promote the rapid entry of the pickling preservation liquid into the shrimp meat tissue. At the same time, the slow-cooking process under vacuum makes the shrimp meat more flavorful, thereby improving the sensory quality of the shrimp meat. The gel network formed by pullulan in the pickling preservation liquid can adsorb the water in the shrimp meat, and the protective hydration layer formed by the hydrophobic interaction between steviol polyphenols and shrimp myofibrillar protein can further reduce water loss, thereby reducing the cooking loss rate of prefabricated shrimp and further ensuring the sensory quality of prefabricated shrimp. (3) Storage test of prefabricated shrimp The prefabricated shrimp prepared in Example 5, Comparative Example 1 and Comparative Example 2 were stored at 4°C, and the juice loss rate, total number of colonies, volatile basic nitrogen content (TVB-N), and texture properties were measured on the 30th day of storage. Among them, the total number of colonies was determined according to GB4789.2-2022; the volatile basic nitrogen was determined by GB5009.228-2016, and the thiobarbituric acid value was determined by GB / T35252-2017. Table 3 Test results of prefabricated shrimp indicators in Example 5, Comparative Example 1 and Comparative Example 2 Example 5 Comparative Example 1 Comparative Example 2 Total number of colonies (CFU / g) 15 84 105 TVB-N (mg / 100g) 6.35 17.72 20.31 Elasticity (mm) 1.42 0.74 0.45 Chewiness (mJ) 8.44 5.38 3.88 Juice loss rate (%) 4.97 8.24 15.83 As can be seen from Table 3, the total number of colonies, TVB-N, elasticity, chewiness and juice loss rate of the prefabricated shrimp prepared in Example 5 were significantly lower than those of Comparative Example 1 and Comparative Example 2 after being stored at 4°C for 30 days, indicating that the polyphenol substances in clove essential oil and stevia leaf polyphenols in the present invention can effectively inhibit the reproduction of harmful microorganisms during the storage of prefabricated shrimp. And the pulsed electric field treatment can achieve a certain bactericidal effect by using the electric field effect. The vacuum environment provided by vacuum packaging is also not conducive to the growth and reproduction of harmful microorganisms. In addition, polyphenol substances have good antioxidant ability, reducing the corruption degree of proteins and fats in prefabricated shrimp, and at the same time giving prefabricated shrimp a longer shelf life. The gel network of pullulan and the protective hydration layer formed by the hydrophobic interaction between polyphenols and shrimp myofibrillar protein constitute a multi-scale water retention system, ensuring less juice loss during storage, so that the prefabricated shrimp has good elasticity and chewiness, and endowing the prefabricated shrimp with good fresh quality. The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Any person skilled in the art can, without departing from the spirit and technical solutions of the present invention, make many possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above, or modify them into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solutions of the present invention still fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A preservation method for prefabricated shrimps, characterized in that, The vacuum slow cooking coupled pulsed electric field technology is used, which specifically includes the following steps: S1. Select fresh, whole shrimp, clean and remove impurities to obtain fresh shrimp meat; S2. The fresh shrimp meat was soaked in a pickling solution and treated with a pulsed electric field to obtain pretreated shrimp meat; S3. The pre-processed shrimp meat is packaged and then slowly cooked under vacuum, and then rapidly cooled to obtain the pre-processed shrimp.

2. The preservation method of prefabricated shrimp according to claim 1, characterized in that: In step S2, the material-liquid ratio of the fresh shrimp meat to the pickling and preservative liquid is 1:(2.5-5).

3. A preservation method for prefabricated shrimp according to claim 1, characterized in that: In step S2, the pickling and preservative liquid is prepared by adding water to the pickling material and the preservative.

4. A preservation method for prefabricated shrimp according to claim 1, characterized in that, The marinade comprises the following components, calculated based on the weight of fresh shrimp meat: 5-10% of table salt, 5-7.5% of white sugar, 3-5% of soy sauce, 1.5-3% of star anise, 0.1-1% of cooking wine and 0.2-0.8% of monosodium glutamate.

5. The method for preserving pre-cooked shrimp according to claim 1, characterized in that: The preservative comprises the following components: 0.2-1.5% of clove essential oil, 0.5-1% of stevia leaf polyphenol, 1.5-2.5% of pullulan, and the balance is water, calculated based on the weight of the pickling preservative liquid.

6. The fresh-keeping method of the prefabricated shrimp according to claim 1, characterized in that: The conditions for the pulse electric field treatment in step S2 are: electric field intensity 1-3 kV / cm, electric field frequency 500-750 Hz, and treatment time 2.5-5 min.

7. A fresh-keeping method for prefabricated shrimp according to claim 1, characterized in that: The vacuum cooking conditions in step S3 are a cooking temperature of 60-80° C. and a cooking time of 5-15 minutes.

8. Pre-cooked shrimp prepared according to the method according to any one of claims 1 to 7.

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