阅读说明：本技术 一种梭子蟹涂膜保鲜方法 (Coating preservation method for swimming crabs ) 是由 王世光 张小军 许丹 于 2019-11-29 设计创作，主要内容包括：本发明公开了一种梭子蟹涂膜保鲜方法,包括以下步骤：(1)冷风吹干；(2)喷雾润面；(3)自然晾干；(4)静电喷雾涂膜；(5)冷风成膜；(6)真空包装冷藏。本发明通过冷风吹干、喷雾润面、自然晾干、静电喷雾涂膜、冷风成膜多个步骤联合处理,在梭子蟹表面形成均匀、透明的涂膜,提高了梭子蟹的外观品质,延长了梭子蟹的保鲜期(相比直接进行真空包装微冻保鲜,可延长保鲜期8～10天),且操作简单,成本低,适合大批量操作。(The invention discloses a coating preservation method for portunids, which comprises the following steps: (1) drying by cold air; (2) spraying and moistening the noodles; (3) naturally drying; (4) electrostatic spray coating; (5) forming a film by cold air; (6) and (5) vacuum packaging and refrigerating. According to the invention, through the combined treatment of multiple steps of cold air blow-drying, surface moistening by spraying, natural airing, electrostatic spray coating and cold air film forming, a uniform and transparent coating is formed on the surface of the portunid, the appearance quality of the portunid is improved, the preservation period of the portunid is prolonged (compared with the direct vacuum packaging and micro-freezing preservation, the preservation period can be prolonged by 8-10 days), and the method is simple to operate, low in cost and suitable for large-scale operation.)

1. A coating preservation method for portunids is characterized by comprising the following steps:

(1) drying with cold air: cleaning fresh portunids, draining water, and blowing the body surfaces of the portunids to be dry and anhydrous by cold air;

(2) spraying and moistening the noodles: carrying out spray treatment on the body surface of the swimming crabs in the step (1) by using slightly acidic electrolyzed water containing phytic acid/chitosan slow-release particles and trehalose to keep the body surface of the swimming crabs moist but not drip;

(3) naturally airing: spreading the portunids in the step (2), and naturally airing the portunids until the surfaces of the portunids are dried;

(4) electrostatic spray coating: uniformly spraying the coating preservation solution on the surface of the portunid in the step (3) in an electrostatic spraying manner;

(5) cold air film forming: performing cold air film forming on the portunid in the step (4);

(6) vacuum packaging and refrigerating: putting the portunid with the film formed on the surface into a transparent packaging bag, vacuumizing, sealing and preserving by micro-freezing.

2. The coating preservation method for the swimming crabs according to claim 1, wherein the temperature of the cold air in the step (1) is 5 to 20 ℃.

3. The coating preservation method of swimming crabs according to claim 1, wherein in the step (2), the phytic acid/chitosan sustained-release particles are prepared by the following method: dissolving chitosan in an acetic acid solution, and filtering after swelling to obtain a chitosan acetic acid solution; adding phytic acid into the sodium tripolyphosphate solution, uniformly stirring, adjusting the pH value to 4.5-5.5, adding the phytic acid into the chitosan acetic acid solution at one time under the stirring state, and filtering and drying after reaction to obtain the phytic acid/chitosan particles.

4. The coating preservation method of swimming crabs according to claim 3, wherein the mass concentration of the acetic acid solution is 1 to 1.2%, the chitosan concentration in the chitosan acetic acid solution is 2 to 4mg/ml, and the mass ratio of the phytic acid to the chitosan is 1: (4-5), wherein the mass ratio of the sodium tripolyphosphate to the chitosan is 1: (3-4), the reaction temperature is 20-25 ℃, and the reaction time is 4-6 min.

5. The coating preservation method of swimming crabs according to claim 1, wherein in the step (2), the pH of the slightly acidic electrolyzed water is 5.0 to 6.5.

6. The coating preservation method of swimming crabs according to claim 1, wherein in the step (3), the natural airing temperature is controlled to be 5-20 ℃.

7. The coating preservation method of swimming crabs according to claim 1, wherein in the step (4), the coating preservation solution comprises the following components by mass percent: 0.3-0.5% of NPS polysaccharide, 0.01-0.03% of sodium dehydroacetate, 1-3% of propylene glycol and the balance of water.

8. The coating preservation method of swimming crabs according to claim 1, wherein in the step (5), the temperature of the cold air is 5 to 15 ℃, and the air speed is controlled to be 1 to 2 m/s.

9. The coating preservation method of swimming crabs according to claim 1, wherein in the step (6), the slightly freezing and refrigerating temperature is-4 to-5 ℃.

Technical Field

The invention relates to a swimming crab preservation method, in particular to a swimming crab film coating preservation method.

Background

Swimming crabs, commonly called white crabs, belong to the crustacea, the decapetalous and the discidae, have tender meat, delicious taste and rich nutrition, and are deeply loved by consumers. The portunids are extremely easy to die after being captured, and meanwhile, crab meat protein is decomposed under the action of enzyme and microorganism to generate alkaline nitrogen-containing substances such as ammonia, amines and the like, so that the freshness and the quality of the portunids are rapidly reduced, and the portunids are further putrefy.

The prior preservation technology for portunids mainly comprises freezing, fluidized ice, air conditioning, ice storage and the like, wherein the freezing can cause the portunids to be consumed, and juice is lost during thawing, so that the original flavor can not be maintained; the air conditioning operation is complex, the cost and the requirement on equipment are high, and the air conditioning operation is not suitable for large-scale application; the ice storage is to embed the swimming crabs in ice blocks for storage, and is the most common preservation method in the market at present, but the ice storage needs a large amount of ice blocks, is inconvenient to transport, and has short preservation period.

The coating preservation technology has been applied to the field of aquatic product preservation as a new technology, but is still in the exploration stage. At present, the swimming crabs at least have the following problems when the coating preservation technology is applied, so that the application of the swimming crabs is limited and the swimming crabs cannot be popularized: (1) the formed coating film has poor glossiness and transparency, and the appearance quality of the swimming crabs can be directly influenced; (2) the shells of the swimming crabs are hard and smooth, the coating liquid is difficult to be uniformly attached to the body surfaces of the swimming crabs to form films, and the film forming effect is poor, so that the actual preservation effect is poor; (3) the method is characterized in that the surface of the swimming crabs is coated by adopting a soaking mode, the swimming crabs have a large amount of water and microorganisms, the soaking coating pollutes coating liquid, and the concentration of the coating liquid is changed.

Therefore, the development of a coating preservation method suitable for portunids has important practical significance.

Disclosure of Invention

The invention aims to solve the problems of the existing swimming crab coating preservation technology, and provides a swimming crab coating preservation method which is simple to operate, low in cost, suitable for large-scale operation, capable of improving the appearance quality of swimming crabs and effectively prolonging the shelf life of the swimming crabs.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention relates to a coating preservation method for swimming crabs, which comprises the following steps:

(1) drying with cold air: cleaning fresh swimming crabs, draining water, and blowing the body surfaces of the swimming crabs to be dry and anhydrous by adopting cold air. According to the invention, cold air is adopted to blow the body surface of the swimming crabs to be dry and anhydrous, so that the slightly acidic electrolyzed water containing phytic acid/chitosan slow-release particles and trehalose can be uniformly attached to the body surface of the swimming crabs in the subsequent spraying and surface moistening procedures.

(2) Spraying and moistening the noodles: and (3) carrying out spray treatment on the body surface of the swimming crabs in the step (1) by using slightly acidic electrolyzed water containing phytic acid/chitosan slow-release particles and trehalose to keep the body surface of the swimming crabs moist but not drip. The invention creatively adds a step of spraying and moistening the noodles, and has two main purposes: firstly, the portunids are subjected to bacteria reduction treatment to prolong the preservation period of the portunids, and secondly, the surface microscopic morphology of the portunids is changed, so that phytic acid/chitosan slow-release particles with positive charges are attached to the surfaces of the portunids, and when the subsequent electrostatic spray coating is carried out, the coating preservation solution (with negative charges) can directly and quickly fly to the phytic acid/chitosan slow-release particles, thereby greatly reducing the loss of fog drops with small particle size, and being beneficial to the uniform attachment of the coating preservation solution and the formation of uniform coating; in the invention, the slightly acidic electrolyzed water containing the phytic acid/chitosan slow-release particles and the trehalose is used as the spray liquid, has excellent sterilization effect, is safe and harmless, and is favorable for dissolving and dispersing the phytic acid/chitosan slow-release particles; the phytic acid/chitosan slow-release particles have positive charges and have excellent antioxidant effect and antibacterial effect, and the phytic acid can inhibit the color fading of the swimming crabs, so that the sensory quality of the swimming crabs is improved, and the freshness date of the swimming crabs is prolonged; the trehalose can improve the fluidity of the subacid electrolyzed water and improve the adhesive property of the subacid electrolyzed water, in addition, a layer of non-hygroscopic protective film can be formed on the surface of the portunid after the trehalose is dried, the preservation period of the portunid can be prolonged, and the trehalose can not be hydrolyzed and discolored, and can not influence the appearance color and luster of the portunid.

(3) Naturally airing: and (3) spreading the swimming crabs in the step (2), and naturally airing the swimming crabs until the surfaces of the swimming crabs are dry.

(4) Electrostatic spray coating: and (4) uniformly spraying the coating preservation solution on the surface of the portunid in the step (3) in an electrostatic spraying manner. The invention adopts electrostatic spray coating, can reduce the waste of fresh-keeping liquid for coating, and the formed coating is uniform and firm in combination with swimming crabs, and improves the performance of the coating.

(5) Cold air film forming: and (4) performing cold air film forming on the portunids in the step (4).

(6) Vacuum packaging and refrigerating: putting the portunid with the film formed on the surface into a transparent packaging bag, vacuumizing, sealing and preserving by micro-freezing.

Preferably, in the step (1), the cold air temperature is 5-20 ℃.

Preferably, in the step (2), the phytic acid/chitosan sustained-release particles are prepared by the following method: dissolving chitosan in an acetic acid solution, and filtering after swelling to obtain a chitosan acetic acid solution; adding phytic acid into the sodium tripolyphosphate solution, uniformly stirring, adjusting the pH value to 4.5-5.5, adding the phytic acid into the chitosan acetic acid solution at one time under the stirring state, and filtering and drying after reaction to obtain the phytic acid/chitosan particles. The phytic acid has excellent antioxidation, but is very easy to oxidize and deliquesce, so that the phytic acid is embedded into capsule particles by taking chitosan as a carrier of the phytic acid and crosslinking the chitosan and sodium tripolyphosphate to solve the problem that the phytic acid is easily oxidized by air and deliquesced, the activity of the phytic acid can be protected, the phytic acid can be slowly released, and the freshness date of the swimming crabs can be prolonged; according to the invention, the sodium tripolyphosphate solution and the phytic acid are mixed and then added into the chitosan acetic acid solution at one time, so that the dispersion uniformity of the phytic acid can be ensured, the sodium tripolyphosphate can be rapidly diffused in the chitosan acetic acid solution, and the sodium tripolyphosphate is prevented from being diffused slowly in the chitosan acetic acid solution to cause overhigh local concentration and cause relatively large particle size to generate flocculent precipitate.

Preferably, the mass concentration of the acetic acid solution is 1-1.2%, the chitosan concentration in the chitosan acetic acid solution is 2-4 mg/ml, and the mass ratio of the phytic acid to the chitosan is 1: (4-5), wherein the mass ratio of the sodium tripolyphosphate to the chitosan is 1: (3-4), the reaction temperature is 20-25 ℃, and the reaction time is 4-6 min.

Preferably, in the step (2), the pH of the slightly acidic electrolyzed water is 5.0 to 6.5.

Preferably, in the step (3), the natural airing temperature is controlled to be 5-20 ℃.

Preferably, in the step (4), the coating preservation solution consists of the following components in percentage by mass: 0.3-0.5% of NPS polysaccharide, 0.01-0.03% of sodium dehydroacetate, 1-3% of propylene glycol and the balance of water. The inventor finds that the NPS polysaccharide has good film-forming property, is colorless and tasteless after forming a film on the surface of the portunid, has good transparency, is difficult to see by naked eyes, obviously enhances the glossiness, is beneficial to improving the sensory quality of the portunid, and has incomparable advantages compared with other film-forming agents, so the NPS polysaccharide is adopted as a film-forming substance in the invention; the propylene glycol is used as a plasticizer, so that the mechanical property of the coating film can be improved; sodium dehydroacetate is a safe food mildew-proof and antiseptic preservative, and is beneficial to prolonging the preservation period of portunids; the coating preservation solution disclosed by the invention is simple in formula, safe and harmless in components, good in water solubility and film forming property, and capable of prolonging the preservation period of the swimming crabs.

Preferably, in the step (5), the temperature of the cold air is 5-15 ℃, and the air speed is controlled to be 1-2 m/s.

Preferably, in the step (6), the temperature of the micro-freezing refrigeration is-4 to-5 ℃.

Preferably, in the step (2), phytic acid/chitosan slow-release particles and trehalose are preferably used in slightly acidic electrolyzed water, and in the step (2), the temperature of the slightly acidic electrolyzed water is 5-10 ℃.

Therefore, the invention has the following beneficial effects: the method has the advantages that the uniform and transparent coating is formed on the surface of the portunid through the combined treatment of multiple steps of cold air blow-drying, surface moistening by spraying, natural airing, electrostatic spraying coating and cold air film forming, so that the appearance quality of the portunid is improved, the preservation period of the portunid is prolonged (the preservation period can be prolonged by 8-10 days compared with the direct vacuum packaging and micro-freezing preservation), the operation is simple, the cost is low, and the method is suitable for large-scale operation.

Drawings

FIG. 1 is a graph showing a comparison of the change tendency of sensory evaluation of the crabs in example 1, comparative examples 1 to 2 and the blank example.

FIG. 2 is a graph showing a comparison of the change tendency of TVB-N values of the blue crabs in example 1, comparative examples 1 to 2 and a blank example.

Detailed Description

The invention is further described with reference to the following figures and detailed description.