Preservative for corrosion prevention of perishable berries and preparation method thereof

Abstract

The invention discloses a preservative for corrosion prevention of perishable berries. The main effective part is a water-absorbing fiber polymer obtained by adding a modified filler A in the polymerization process of a polymer mixture, and a water-absorbing fiber sponge block obtained by adsorbing and slowly releasing an active component B. The preparation method comprises the following steps: S1, dispersing PVA, PVP and PAA-PAM in water, adding the modified filler A, and carrying out high-speed stirring dispersion, so as to obtain a modified fiber polymer; s2, preparing the modified fiber polymer into a sponge plate material; s3, adding sodium phosphite, a buffer agent, a disodium hydrogen phosphate hexadecahydrate solution and a hydrogen peroxide solution into water to obtain a slow-release active component B; and S4, spraying the slow-release active component B on the sponge plate material, cutting the sponge plate material into sponge blocks, and carrying out plastic sealing, thereby obtaining the product. According to the preservative, chlorine dioxide gas can be stably released, the adsorption amount of chlorine dioxide reactants can be greatly increased, and the preservative can be suitable for various preservation processes of perishable berries from picking to racking.

Description

Technical Field

[0001] The invention belongs to the field of preservatives, and in particular relates to a preservative for preserving perishable berries and a preparation method thereof. Background Art

[0002] Chlorine dioxide is a substance that has been widely used in various fields such as disinfection, sterilization, and deodorization in recent years. Because of its good diffusivity and low residue, it is harmless and non-irritating to humans, animals, and plants at appropriate effective concentrations; the disinfection product has no teratogenic, mutagenic, or carcinogenic effects. The strong oxidizing property of chlorine dioxide makes it have a broad-spectrum and effective killing effect on most viruses and other pathogenic microorganisms in the air and on the surface of objects. The World Health Organization of the United Nations has classified it as a Class A1 disinfectant, recognizing its effectiveness and safety in a wide range of fields. At the same time, chlorine dioxide is also used in the field of fruit preservation. By releasing trace amounts of chlorine dioxide gas, it can effectively kill molds and other harmful microorganisms in the air that may cause fresh fruits, vegetables, and grains to spoil, thereby playing a role in preservation and antiseptic treatment. For example, for gray mold that appears on moldy fresh fruits, 0.01mg / m 3 High concentration of chlorine dioxide gas can remove mold on the fruit skin in a small space, killing more than 99% of it within 2 hours. At the same time, chlorine dioxide can inhibit the ethylene binding receptors of the fruit skin and the ethylene produced by itself, which can delay the ripening of the fruit to a certain extent, reduce the rate of biochemical reactions inside the fruit, and achieve the purpose of fruit preservation.

[0003] However, in practical applications, chlorine dioxide is relatively difficult to preserve and is prone to decomposition and disproportionation reactions, thereby losing its activity. Conventional chlorine dioxide products are often prepared on-site, using chlorite and acid to obtain chlorine dioxide gas or solution. Air freshener products are made by mixing agent A, which is mainly composed of sodium chlorite, with agent B, which is a mixture of an acid activator, a stabilizer, and a gelling agent, with water. By adjusting the concentration of the reactants and the amount of the matrix, the release of chlorine dioxide gas is controlled to form a stable gel to achieve the effect of air disinfection.

[0004] However, when such products are applied to the field of fruit and vegetable preservation, they usually encounter several problems: First, due to the unique properties of chlorine dioxide, most gel component materials with water-absorbing properties cannot maintain the stable release of chlorine dioxide for a long time. When chlorite is activated, the pH in the solution system will gradually decrease, and the activity of the strong oxidizing substances inside the system will become increasingly greater, causing the stability of the carrier material (especially the hydrogel-like organic polymer material) to be greatly weakened, causing it to be rapidly degraded by chlorine dioxide during the sustained release process, and the carrier loses its water-retaining and solidifying function to intercept chlorine dioxide. This makes the release time of the chlorine dioxide sustained-release agent used for fruit and vegetable preservation fail to meet expectations, and cannot collaboratively complete the entire process of fresh fruits and vegetables from picking to shelving.

[0005] Secondly, the release amount of most chlorine dioxide slow-release materials during the stabilization period cannot meet the needs of fruit and vegetable preservation. The main reason for this problem is that the chlorine dioxide slow-release agent will burst after activation. After a period of burst release, the content of chlorine dioxide effective ingredients in the material will be greatly reduced, and the effect of long-term preservation cannot be achieved. In addition, the high concentration of chlorine dioxide released by the material during the burst release period will cause certain damage to fresh fruits, especially for berries with many anthocyanins. Excessive instantaneous concentration of chlorine dioxide will cause serious degradation, affecting the taste and color of the fruit. But more often in the typical process of picking-cold storage-cold chain transportation-fruit shelving, the fruit has been kept in a low temperature, light-proof and high humidity environment, and the chlorine dioxide slow-release preservative cannot reach the normal activation state, and the concentration of the disinfection and preservation gas it can supply is far from meeting the demand. The reason is that the total mass of chlorine dioxide reactants (i.e., slow-release active ingredients) adsorbed in the chlorine dioxide slow-release agent adsorbed by the slow-release substrate is too small. In order to balance the chemical stability during production, usually too concentrated chlorite solution cannot be adsorbed into the slow-release agent. However, many common slow-release agents have the problem of low water absorption rate for brine. For the same material, the ratio of adsorbed water and brine is nearly 10:1. This sometimes means that there are not enough reactants to support the long-term action of the preservative and the anti-mildew and ripening inhibition, thus failing to achieve the preservation effect. Summary of the invention

[0006] The object of the present invention is to provide a preservative for preserving perishable berries and a preparation method thereof, so as to solve the technical problems existing in the above-mentioned prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A preservative for preserving perishable berries. The main effective part of the preservative is a water-absorbing fiber polymer obtained by adding a modified filler A to a polymer mixture during polymerization, and a water-absorbing fiber sponge block obtained by absorbing and slowly releasing an active ingredient B.

[0009] Furthermore, the modified filler A is an alkaline earth metal-based modified inorganic material with a layered structure.

[0010] Furthermore, the modified filler A is calcium hydrochloride-based bentonite.

[0011] Furthermore, the polymer mixture is composed of the following raw materials in weight percentage: PVA 15% to 25%, PVP 5% to 15%, and PAA-PAM 65% to 80%.

[0012] Furthermore, the sustained-release active ingredient B comprises the following raw materials in percentage by weight: 1% to 18% sodium chlorite, 0.5% to 5.0% potassium dihydrogen phosphate dihydrate or anhydrous potassium dihydrogen phosphate, 0.1% to 1.0% disodium hydrogen phosphate hexahydrate solution, 0.01% to 0.1% 30% hydrogen peroxide solution, and deionized water to make up.

[0013] A preservative for perishable berries, characterized by comprising the following steps:

[0014] S1: PVA, PVP and PAA-PAM are mixed and dispersed in an aqueous solution at 45-65°C, and the modified filler A is added in 3-5 times, and high-stirring dispersion is performed at a speed of 35-45 Hz; after the dispersion is completed, the temperature is raised to 65-80°C and stirring is continued for 1-1.5 hours. After the stirring is completed, the mixture is filtered and dried at 45-55°C to a moisture content of ≤5% to obtain a modified fiber polymer;

[0015] S2: The modified fiber polymer is made into a fiber with a density of 20-35 kg / m by wet spinning, melt blowing or direct bonding. 3 , sponge board material with a thickness of 2 to 2.5 mm;

[0016] S3: adding sodium phosphite, a buffer, a solution of disodium hydrogen phosphate hexadecahydrate, and a hydrogen peroxide solution into deionized water, stirring evenly to fully dissolve the inorganic salt, and adjusting the pH value to 4.5 to 6.5 to obtain a sustained-release active ingredient B;

[0017] S4: Use a nozzle to evenly spray the sustained-release active ingredient B on the sponge board material prepared in S2 at a flow rate of 80-100g / m2 under the conditions of 15-25℃ and humidity ≤50%, so that the sponge board material can fully absorb the sustained-release active ingredient B. After the adsorption is completed, the sponge board material is transferred to a freeze dryer and freeze-dried for 6-8h at -10--25℃ and a vacuum degree of ≤-0.09Mpa. After drying, the temperature is raised at 0-4℃. Finally, the sponge board material is cut into sponge blocks, and the upper and lower surfaces of the sponge blocks are sealed with plastic to obtain a preservative.

[0018] Furthermore, in step S2, the sponge board material is made by melt spraying, and the specific method is: the obtained modified fiber polymer is crushed, isolated from the air to melt it, and then the solvent additive is quickly sprayed into a closed cavity through a nozzle, and the sponge board material is obtained after it is quickly cooled and formed.

[0019] Furthermore, in step S4, the cutting size of the sponge block is 20×20 mm.

[0020] Furthermore, in step S4, the upper and lower surfaces of the sponge block are sealed with wax paper or aluminum-plastic cardboard by heat sealing, hot-melt bonding, or adhesive bonding.

[0021] Furthermore, the upper and lower surfaces of the sponge block are sealed with plastic by bonding with wax paper through an adhesive.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention introduces alkaline earth metal-based modified inorganic materials into the polymer mixture, and effectively improves the stability of the preservative through the synergistic effect of the internal conjugate acid-base pair, so that the chlorine dioxide system can be maintained in a suitable release environment, so that the chlorine dioxide gas can be stably released, and at the same time, the adsorption amount of chlorine dioxide reactants can be greatly increased to prevent the occurrence of explosive release. The chlorine dioxide release amount is moderate and will not affect the appearance, color and flavor of fresh fruits. It can be applied to various preservation processes of perishable berries from picking to shelving.

[0024] 2. The preservative of the present invention is quick to produce, low in cost, easy to store and transport, does not require the addition of drugs for activation, can be used immediately after unsealing, is small in size, can be flexibly placed in packaging forms of various specifications, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a curve diagram of chlorine dioxide gas release of the preservative of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are only for the purpose of enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

[0027] A preservative for preserving perishable berries. The main effective part of the preservative is a water-absorbing fiber polymer obtained by adding a modified filler A to a polymer mixture during polymerization, and a water-absorbing fiber sponge block obtained by absorbing and slowly releasing an active ingredient B.

[0028] The modified filler A is 0.25% to 0.45% of calcium hydrochloride-based bentonite or calcium magnesium hydrotalcite sepiolite and other alkaline earth metal-based modified inorganic materials with a layered structure, with a fineness of 120 to 180 meshes and a moisture content of ≤1.0%.

[0029] The polymer mixture is composed of the following raw materials in weight percentage: 15% to 25% of polyvinyl alcohol (PVA), 5% to 15% of polypropylene pyrrolidone (PVP), and 65% to 80% of polyacrylic acid-polyacrylic acid amide (PAA-PAM).

[0030] In another embodiment, the polymer mixture may also use carboxymethyl cellulose CMC and polyethylene glycol PEG. Since the strength of these two polymers is relatively low, the space for adding fillers is relatively limited. In order to ensure uniform dispersion, about 0.01% of anti-settling agent should be added.

[0031] The sustained-release active ingredient B comprises the following raw materials in percentage by weight: 1% to 18% sodium chlorite, 0.5% to 5.0% potassium dihydrogen phosphate dihydrate or anhydrous potassium dihydrogen phosphate, 0.1% to 1.0% disodium hydrogen phosphate hexahydrate solution, 0.01% to 0.1% 30% hydrogen peroxide solution, and deionized water as a supplement.

[0032] A preservative for preserving perishable berries, comprising the following steps:

[0033] S1: PVA, PVP and PAA-PAM are mixed and dispersed in an aqueous solution at 45-65°C, potassium persulfate initiator is added, and modified filler A is added in 3-5 times, and high-stirring dispersion is performed at a speed of 35-45 Hz; after dispersion, the temperature is raised to 65-80°C and stirring is continued for 1-1.5 hours, after stirring, it is filtered, and dried in a circulating air oven at a temperature of 45-55°C until the moisture content is ≤5% as determined by the volatile matter test at 105°C, to obtain a modified fiber polymer;

[0034] S2: The modified fiber polymer is made into a fiber with a density of 20-35 kg / m by wet spinning, melt blowing or direct bonding. 3 , sponge board material with a thickness of 2.0 to 2.5 mm;

[0035] S3: Add sodium phosphite, potassium dihydrogen phosphate dihydrate or anhydrous potassium dihydrogen phosphate, disodium hydrogen phosphate hexadecahydrate solution, and hydrogen peroxide solution into deionized water, stir evenly to fully dissolve the inorganic salt, and adjust the pH value to 4.5-6.5 to obtain the sustained-release active ingredient B, which is sealed and stored in a dark container to avoid direct sunlight and water loss. The product can be stored for ≥30 days;

[0036] S4: Use a saline spray nozzle treated with corrosion inhibitor to spray the sustained-release active ingredient B at a rate of 80-100 g / m at 15-25°C and a humidity of ≤50%. 2 The flow rate is evenly sprayed on the sponge board material prepared in S2, so that the sponge board material can fully absorb the sustained-release active ingredient B. After the adsorption is completed, the sponge board material is quickly transferred to a freeze dryer and freeze-dried for 6 to 8 hours at -10 to -25°C and a vacuum degree of ≤-0.09Mpa. After drying, it is heated in a refrigerator at 0 to 4°C. Finally, the sponge board material is cut into sponge blocks with a size of 20×20 mm, and the upper and lower surfaces of the sponge blocks are sealed with wax paper or aluminum-plastic cardboard by heat sealing, hot-melt bonding, or adhesive bonding to obtain a preservative.

[0037] After the sponge block is sealed with plastic, the top surface can be printed with artistic shapes or manufacturer logos, and product certificate information can also be printed, and the bottom surface can be attached with double-sided self-adhesive stickers.

[0038] The preservative should be stored in a refrigerator at 0-4℃. Before being put into use, it should be kept in a nitrogen-filled plastic sealed bag and stored in a light-proof environment at ≤25℃ for ≥90 days.

[0039] The principle of the present invention is: the alkaline earth metal-based modified inorganic material with a layered structure is conducive to the alkaline earth metal providing slow-release acid and alkali substances adsorbed on its layered structure, so that the active ingredient B with slow-release of chlorine dioxide is maintained in a stable chemical environment, so that its concentration, pH and the amount of reaction by-products can be controlled within a suitable range. The calcium-based bentonite modified with hydrochloric acid can maintain the pH value of the system between 4.0 and 6.0 for a long time. In this pH range, the slow-release rate is the most stable, so that chlorine dioxide can be released stably.

[0040] In the polymer polymerization process, alkaline earth metal-based modified inorganic materials are introduced to enable the alkaline earth metal-based modified inorganic materials to be embedded in the cross-linked and entangled polymer segments. Since part of the space in each polymer segment is blocked by fillers, the extent of entanglement and contraction is reduced compared to the formula without fillers. The pore spacing between the segments can accommodate the anions and cations of inorganic salts with larger molecular diameters to enter the system, so that it has more space to absorb salt water, increase its adsorption of salt water, and significantly increase the adsorption of chlorine dioxide reactants. At the same time, due to the increase in inorganic components, the rigidity of the entire system is enhanced and the flexibility is reduced, making it more conducive to processing.

[0041] The following is a more specific example.

[0042] Example 1

[0043] A preservative for preserving perishable berries. The main effective part of the preservative is a water-absorbing fiber polymer obtained by adding a modified filler A to a polymer mixture during polymerization, and a water-absorbing fiber sponge block obtained by absorbing and slowly releasing an active ingredient B.

[0044] The modified filler A is 0.25% calcium hydrochloride-based bentonite.

[0045] The polymer mixture is composed of the following raw materials in weight percentage: PVA 25%, PVP 5%, PAA-PAM 70%.

[0046] The sustained-release active ingredient B comprises the following raw materials in percentage by weight: 10% sodium chlorite, 3% potassium dihydrogen phosphate dihydrate, 0.4% disodium hydrogen phosphate hexadecahydrate solution, 0.01% 30% hydrogen peroxide solution, and deionized water as a supplement.

[0047] A preservative for preserving perishable berries, comprising the following steps:

[0048] S1: PVA, PVP and PAA-PAM are mixed and dispersed in an aqueous solution at 50°C, potassium persulfate initiator is added, and modified filler A is added three times, and high-stirring dispersion is performed at a speed of 40 Hz; after dispersion, the temperature is raised to 70°C and stirring is continued for 1 hour, and after stirring, the mixture is filtered and dried in a circulating air oven at a temperature of 50°C to a moisture content of ≤5% to obtain a modified fiber polymer;

[0049] S2: The modified fiber polymer is made into a sponge board material by a melt spraying method. The specific method is as follows: the obtained modified fiber polymer is crushed, and after being isolated from air to melt, a solvent additive is quickly sprayed into a closed cavity through a nozzle, and after it is quickly cooled and formed, a density of 25kg / m 3 , sponge board material with a thickness of 2mm;

[0050] S3: adding sodium phosphite, a buffer, a sodium hydrogen phosphate hexadecahydrate solution, and a hydrogen peroxide solution into deionized water, stirring evenly to fully dissolve the inorganic salt, and adjusting the pH value to 5.9 to obtain a sustained-release active ingredient B;

[0051] S4: Use a saline spray nozzle treated with corrosion inhibitor to spray the sustained-release active ingredient B at 85 g / m 2The flow rate is evenly sprayed on the sponge board material prepared in S2, so that the sponge board material can fully absorb the sustained-release active ingredient B. After the adsorption is completed, the sponge board material is quickly transferred to a freeze dryer and freeze-dried for 8 hours at -25°C and a vacuum degree of ≤-0.09Mpa. After drying, it is heated in a refrigerator at 4°C. Finally, the sponge board material is cut into sponge blocks with a size of 20×20mm, and the upper and lower surfaces of the sponge blocks are sealed with wax paper by bonding with an adhesive to obtain a preservative.

[0052] Example 2

[0053] A preservative for preserving perishable berries. The main effective part of the preservative is a water-absorbing fiber polymer obtained by adding a modified filler A to a polymer mixture during polymerization, and a water-absorbing fiber sponge block obtained by absorbing and slowly releasing an active ingredient B.

[0054] The modified filler A is 0.3% calcium hydrochloride-based bentonite.

[0055] The polymer mixture is composed of the following raw materials in weight percentage: PVA 15%, PVP 10%, PAA-PAM 75%.

[0056] The sustained-release active ingredient B comprises the following raw materials in percentage by weight: 5% sodium chlorite, 0.5% potassium dihydrogen phosphate dihydrate, 0.8% disodium hydrogen phosphate hexadecahydrate solution, 0.05% 30% hydrogen peroxide solution, and deionized water as a supplement.

[0057] A preservative for preserving perishable berries, comprising the following steps:

[0058] S1: PVA, PVP and PAA-PAM are mixed and dispersed in an aqueous solution at 45°C, potassium persulfate initiator is added, and modified filler A is added in 4 portions, and high-stirring dispersion is performed at a speed of 45 Hz; after dispersion, the temperature is raised to 75°C and stirring is continued for 1.5 hours, and after stirring, the mixture is filtered and dried in a circulating air oven at a temperature of 45°C to a moisture content of ≤5% to obtain a modified fiber polymer;

[0059] S2: The modified fiber polymer is used to make a sponge board material by a melt spraying method. The specific method is as follows: the obtained modified fiber polymer is crushed, and after being isolated from air to melt, a solvent additive is quickly sprayed into a closed cavity through a nozzle, and after it is quickly cooled and formed, a density of 20kg / m 3 , sponge board material with a thickness of 2.2mm;

[0060] S3: adding sodium phosphite, a buffer, a sodium hydrogen phosphate hexadecahydrate solution, and a hydrogen peroxide solution into deionized water, stirring evenly to fully dissolve the inorganic salt, and adjusting the pH value to 6.5 to obtain a sustained-release active ingredient B;

[0061] S4: Use a saline spray nozzle treated with corrosion inhibitor to spray the sustained-release active ingredient B at 80 g / m 2 The flow rate is evenly sprayed on the sponge board material prepared in S2, so that the sponge board material can fully absorb the sustained-release active ingredient B. After the adsorption is completed, the sponge board material is quickly transferred to a freeze dryer and freeze-dried for 6 hours at -15°C and a vacuum degree of ≤-0.09Mpa. After drying, it is heated in a refrigerator at 0°C. Finally, the sponge board material is cut into sponge blocks with a size of 20×20mm, and the upper and lower surfaces of the sponge blocks are sealed with wax paper by heat sealing to obtain a preservative.

[0062] Example 3

[0063] A preservative for preserving perishable berries. The main effective part of the preservative is a water-absorbing fiber polymer obtained by adding a modified filler A to a polymer mixture during polymerization, and a water-absorbing fiber sponge block obtained by absorbing and slowly releasing an active ingredient B.

[0064] The modified filler A is 0.45% calcium hydrochloride-based bentonite.

[0065] The polymer mixture is composed of the following raw materials in weight percentage: PVA 20%, PVP 15%, PAA-PAM 65%.

[0066] The sustained-release active ingredient B comprises the following raw materials in percentage by weight: 1% sodium chlorite, 5.0% anhydrous potassium dihydrogen phosphate, 0.5% disodium hydrogen phosphate hexahydrate solution, 0.08% 30% hydrogen peroxide solution, and deionized water as a supplement.

[0067] A preservative for preserving perishable berries, comprising the following steps:

[0068] S1: PVA, PVP and PAA-PAM were mixed and dispersed in an aqueous solution at 60°C, potassium persulfate initiator was added, and modified filler A was added in 5 times, and high-stirring dispersion was performed at a speed of 35 Hz; after dispersion, the temperature was raised to 80°C and stirring was continued for 1.2 hours, and after stirring, the mixture was filtered and dried in a circulating air oven at a temperature of 55°C to a moisture content of ≤5% to obtain a modified fiber polymer;

[0069] S2: The modified fiber polymer is used to make a sponge board material by a melt spraying method. The specific method is as follows: the obtained modified fiber polymer is crushed, and after being isolated from air to melt, a solvent additive is quickly sprayed into a closed cavity through a nozzle, and after it is quickly cooled and formed, a density of 35kg / m 3 , sponge board material with a thickness of 2.5mm;

[0070] S3: adding sodium phosphite, anhydrous potassium dihydrogen phosphate, disodium hydrogen phosphate hexadecahydrate solution, and hydrogen peroxide solution into deionized water, stirring evenly to fully dissolve the inorganic salt, and adjusting the pH value to 4.5 to obtain a sustained-release active ingredient B;

[0071] S4: Use a saline spray nozzle treated with corrosion inhibitor to spray the sustained-release active ingredient B at 90 g / m 2 The flow rate is evenly sprayed on the sponge board material prepared in S2, so that the sponge board material can fully absorb the sustained-release active ingredient B. After the adsorption is completed, the sponge board material is quickly transferred to a freeze dryer and freeze-dried for 7 hours at -20°C and a vacuum degree of ≤-0.09Mpa. After drying, it is heated in a refrigerator at 1°C. Finally, the sponge board material is cut into sponge blocks with a size of 20×20mm, and the upper and lower surfaces of the sponge blocks are sealed with plastic by hot-melt bonding of aluminum-plastic cardboard to obtain a preservative.

[0072] Example 4

[0073] A preservative for preserving perishable berries. The main effective part of the preservative is a water-absorbing fiber polymer obtained by adding a modified filler A to a polymer mixture during polymerization, and a water-absorbing fiber sponge block obtained by absorbing and slowly releasing an active ingredient B.

[0074] The modified filler A is 0.4% calcium hydrochloride-based bentonite.

[0075] The polymer mixture is composed of the following raw materials in weight percentage: PVA 15%, PVP 5%, PAA-PAM 80%.

[0076] The sustained-release active ingredient B comprises the following raw materials in percentage by weight: 15% sodium chlorite, 1% anhydrous potassium dihydrogen phosphate, 0.1% disodium hydrogen phosphate hexahydrate solution, 0.1% 30% hydrogen peroxide solution, and deionized water as a supplement.

[0077] A preservative for preserving perishable berries, comprising the following steps:

[0078] S1: PVA, PVP and PAA-PAM are mixed and dispersed in an aqueous solution at 65°C, potassium persulfate initiator is added, and modified filler A is added three times, and high-stirring dispersion is performed at a speed of 40 Hz; after dispersion, the temperature is raised to 65°C and stirring is continued for 1 hour, and after stirring, the mixture is filtered and dried in a circulating air oven at a temperature of 50°C to a moisture content of ≤5% to obtain a modified fiber polymer;

[0079] S2: The modified fiber polymer is made into a fiber with a density of 30kg / m by wet spinning. 3 , sponge board material with a thickness of 2mm;

[0080] S3: adding sodium phosphite, anhydrous potassium dihydrogen phosphate, disodium hydrogen phosphate hexadecahydrate solution, and hydrogen peroxide solution into deionized water, stirring evenly to fully dissolve the inorganic salt, and adjusting the pH value to 5.5 to obtain a sustained-release active ingredient B;

[0081] S4: Use a saline spray nozzle treated with corrosion inhibitor to spray the sustained-release active ingredient B at a rate of 100 g / m at 25°C and a humidity of ≤50%. 2 The flow rate is evenly sprayed on the sponge board material prepared in S2, so that the sponge board material can fully absorb the sustained-release active ingredient B. After the adsorption is completed, the sponge board material is quickly transferred to a freeze dryer and freeze-dried for 6.5 hours at -18°C and a vacuum degree of ≤-0.09Mpa. After drying, it is heated in a refrigerator at 2°C. Finally, the sponge board material is cut into sponge blocks with a size of 20×20mm, and the upper and lower surfaces of the sponge blocks are sealed with plastic cardboard by bonding with an adhesive to obtain a preservative.

[0082] Example 5

[0083] A preservative for preserving perishable berries. The main effective part of the preservative is a water-absorbing fiber polymer obtained by adding a modified filler A to a polymer mixture during polymerization, and a water-absorbing fiber sponge block obtained by absorbing and slowly releasing an active ingredient B.

[0084] The modified filler A is 0.35% calcium hydrochloride-based bentonite.

[0085] The polymer mixture is composed of the following raw materials in weight percentage: PVA 18%, PVP 12%, PAA-PAM 70%.

[0086] The sustained-release active ingredient B comprises the following raw materials in percentage by weight: 18% sodium chlorite, 0.8% potassium dihydrogen phosphate dihydrate, 1.0% disodium hydrogen phosphate hexadecahydrate solution, 0.02% 30% hydrogen peroxide solution, and deionized water as a supplement.

[0087] A preservative for preserving perishable berries, comprising the following steps:

[0088] S1: PVA, PVP and PAA-PAM are mixed and dispersed in an aqueous solution at 50°C, potassium persulfate initiator is added, and modified filler A is added in 4 portions, and high-stirring dispersion is performed at a speed of 35 Hz; after dispersion, the temperature is raised to 80°C and stirring is continued for 1.5 hours, and after stirring, the mixture is filtered and dried in a circulating air oven at 50°C to a moisture content of ≤5% to obtain a modified fiber polymer;

[0089] S2: The modified fiber polymer is directly bonded to form a density of 35kg / m 3 , sponge board material with a thickness of 2.4mm;

[0090] S3: adding sodium phosphite, a buffer, a sodium hydrogen phosphate hexadecahydrate solution, and a hydrogen peroxide solution into deionized water, stirring evenly to fully dissolve the inorganic salt, and adjusting the pH value to 6.2 to obtain a sustained-release active ingredient B;

[0091] S4: Use a saline spray nozzle treated with corrosion inhibitor to spray the sustained-release active ingredient B at a rate of 95 g / m 2 The flow rate is evenly sprayed on the sponge board material prepared in S2, so that the sponge board material can fully absorb the sustained-release active ingredient B. After the adsorption is completed, the sponge board material is quickly transferred to a freeze dryer and freeze-dried for 7.5 hours at -10°C and a vacuum degree of ≤-0.09Mpa. After drying, it is heated in a refrigerator at 3°C. Finally, the sponge board material is cut into sponge blocks with a size of 20×20mm, and the upper and lower surfaces of the sponge blocks are sealed with wax paper by hot-melt bonding to obtain a preservative.

[0092] 1. Detection of chlorine dioxide release of preservative

[0093] According to the method of Example 1, a preservative was prepared, unpacked, and placed in an environment of 0-4°C. Eight tablets were placed in a simulated 2.5L sealed space, and the chlorine dioxide gas release was detected. The chlorine dioxide release curve of the preservative was recorded and plotted. Figure 1 shown.

[0094] from Figure 1 It can be seen that the preservative of the present invention can stably release chlorine dioxide gas for more than 15 days at a concentration below 20 ppm, indicating that the preservative of the present invention has good sustained-release performance and stability, and can meet the needs of fruit and vegetable preservation.

[0095] 2. Detection of preservation status and instantaneous concentration accumulation of preservative chlorine dioxide

[0096] In the sealed space, 8 hollow plastic fruit baskets containing 100-120 g of fresh blueberries were placed to fill a carton of about 5 L without leaving any gaps. A piece of preservative prepared according to the method of Example 1 was placed at the bottom of each plastic fruit box.

[0097] The cartons were placed in a refrigerator at 4±0.5℃ with circulating air, and stored in another refrigerator compartment together with the control group without preservatives.

[0098] In order to confirm the protective effect on fruits with scars, one of the top blueberries in four of the eight fruit boxes was damaged artificially to cause scars. The status of the experimental group and the control group was recorded on days 1, 7, 10, 14, and 20, and the instantaneous concentration accumulation of chlorine dioxide was measured, as shown in Table 1.

[0099] Table 1 Fresh-keeping status and instantaneous accumulation value of chlorine dioxide concentration

[0100]

[0101]

[0102] As can be seen from Table 1, the preservative of the present invention can play an obvious preservative effect on fresh blueberries in various states, and can extend the shelf life from 7 to 10 days to at least 14 days. It also has a significant inhibitory effect on the further decay and mildew of scarred fruits and the rapid spread to nearby fruits, and has a good preservative effect.

[0103] The accumulation of chlorine dioxide is moderate and maintained at 5-20 mg / m 3 The time within the concentration range is greater than 20 days, and the fruit does not discolor due to oxidation, which makes it highly safe.

[0104] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A preservative for perishable berries, characterized in that: The main effective part of the preservative is the absorbent fiber polymer obtained by adding the modified filler A to the polymer mixture during the polymerization process, and the absorbent fiber sponge block obtained by absorbing and slowly releasing the active ingredient B.

2. A preservative for perishable berries according to claim 1, characterized in that: The modified filler A is an alkaline earth metal-based modified inorganic material with a layered structure.

3. A preservative for perishable berries according to claim 2, characterized in that: The modified filler A is calcium hydrochloride-based bentonite.

4. A preservative for perishable berries according to claim 1, characterized in that: The polymer mixture is composed of the following raw materials in weight percentage: PVA 15%-25%, PVP 5%-15%, PAA-PAM 65%-80%.

5. The preservative for perishable berries according to claim 1, characterized in that: The sustained-release active ingredient B comprises the following raw materials in percentage by weight: 1% to 18% sodium chlorite, 0.5% to 5.0% potassium dihydrogen phosphate dihydrate or anhydrous potassium dihydrogen phosphate, 0.1% to 1.0% disodium hydrogen phosphate hexahydrate solution, 0.01% to 0.1% 30% hydrogen peroxide solution, and deionized water as a supplement.

6. A preservative for preserving perishable berries according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: PVA, PVP and PAA-PAM are mixed and dispersed in aqueous solution at 45-65°C, and modified filler A is added in 3-5 portions, and high-stirring dispersion is performed at a rotation speed of 35-45 Hz; After the dispersion is completed, the temperature is raised to 65-80°C and stirring is continued for 1-1.5 hours. After the stirring is completed, the mixture is filtered and dried at 45-55°C until the moisture content is ≤5% to obtain a modified fiber polymer. S2: The modified fiber polymer is made into a fiber with a density of 20-35 kg / m by wet spinning, melt blowing or direct bonding. 3 , sponge board material with a thickness of 2 to 2.5 mm; S3: adding sodium phosphite, a buffer, a solution of disodium hydrogen phosphate hexadecahydrate, and a hydrogen peroxide solution into deionized water, stirring evenly to fully dissolve the inorganic salt, and adjusting the pH value to 4.5 to 6.5 to obtain a sustained-release active ingredient B; S4: Use a nozzle to evenly spray the sustained-release active ingredient B on the sponge board material prepared in S2 at a flow rate of 80-100g / m2 under the conditions of 15-25℃ and humidity ≤50%, so that the sponge board material can fully absorb the sustained-release active ingredient B. After the adsorption is completed, the sponge board material is transferred to a freeze dryer and freeze-dried for 6-8h at -10--25℃ and a vacuum degree of ≤-0.09Mpa. After drying, the temperature is raised at 0-4℃. Finally, the sponge board material is cut into sponge blocks, and the upper and lower surfaces of the sponge blocks are sealed with plastic to obtain a preservative.

7. A preservative for perishable berries according to claim 6, characterized in that: In step S2, the sponge board material is made by melt spraying, specifically, the modified fiber polymer is crushed, isolated from air to melt it, and then a solvent additive is quickly sprayed into a closed cavity through a nozzle, and the sponge board material is obtained after it is quickly cooled and formed.

8. A preservative for perishable berries according to claim 6, characterized in that: In step S4, the sponge block is cut to a size of 20×20 mm.

9. A preservative for perishable berries according to claim 6, characterized in that: In step S4, the upper and lower surfaces of the sponge block are sealed with wax paper or aluminum-plastic cardboard by heat sealing, hot-melt bonding, or adhesive bonding.

10. A preservative for perishable berries according to claim 9, characterized in that: The upper and lower surfaces of the sponge block are sealed with plastic by bonding with wax paper through an adhesive.

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