Preparation method of slow-release solid preservative

Abstract

The invention discloses a preparation method of a slow-release solid preservative, and relates to the field of fruit preservation, and the preservative is prepared from the following raw materials in parts by weight: 5-8 parts of chitosan, 2-4 parts of carrageenan, 1-5 parts of sodium citrate, 2-3 parts of silicon dioxide, 3-4 parts of 1-methylcyclopropene, 2-3 parts of chlorine dioxide, 1-2 parts of water and 3-6 parts of baking soda. The preservation method of the slow-release solid preservative comprises the following steps: loading the solid preservative in a non-woven bag, placing the non-woven bag in a foam box or a packaging bag loaded with fruits, and sealing the foam box or the packaging bag. The baking soda in the preservative releases carbon dioxide, 1-methylcyclopropene and chlorine dioxide, and meanwhile, the physiological metabolism of the fruits and the generation of ethylene are effectively inhibited, and pathogenic bacteria are killed, so that the shelf life of the fruits is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of fruit preservation, in particular to a method for preparing a sustained-release solid preservative. Background Art

[0002] As people's demand for fruits in different regions and seasons gradually increases, and fruits face higher requirements in terms of preservation, storage and transportation, it has become necessary to adapt preservatives to preserve fruits. For example, the patented solid preservative with publication number CN107568560A is composed of the following raw materials and their weight ratios: 15-20 parts of sodium polypropionate, 30-35 parts of houttuynia cordata powder, 5-8 parts of trehalose, 10-15 parts of glucose oxidase, 4-6 parts of cinnamon bark extract, 1-2 parts of ginger powder, 4-8 parts of tea polyphenols, 2-4 parts of sodium citrate, and 20-30 parts of starch. The present invention makes the preservative into granules, which is not only easy to store and transport, but also can be easily formulated into a liquid preservative and easy to use. It can effectively inhibit bacteria and resist viruses, and can form a preservative film on the surface of fruits, vegetables, or aquatic products to maintain the freshness of fruits, vegetables, and aquatic products for a long time. Another example is a sublimation-type solid preservative disclosed in patent publication number CN107494706A. The preservative comprises the following raw materials in parts by weight: 10-15 parts potassium iodide, 5-8 parts solid phosphorus, 5-10 parts cellulose, 8-10 parts nisin, 8-10 parts lactoferrin, 1-2 parts adhesive, and 5-10 parts colloid. The preservative mixture is mixed with a sublimation carrier, and the colloid and adhesive are added while stirring to obtain a colloidal preservative. The colloidal preservative is then cured in a 5-10% glucose solution for 24-48 hours and then heated to remove water. The preservative is obtained. A preparation method of the solid preservative is also disclosed. The preservative can release effective preservative ingredients through sublimation of the substances, and has a significant and long-lasting preservative effect. For example, patent publication number CN107047741A discloses a fruit preservative and its preparation method, which relates to the field of fruit preservation technology. The preservative comprises chitosan, beeswax, glycerin, natural plant extracts, calcium chloride, sodium bicarbonate, proanthocyanidins, vitamin E, citric acid, plant growth regulators, and water. The preparation method comprises the following steps: preparing the natural plant extract; preparing an aqueous preservative; preparing a solid preservative powder; and mixing the aqueous preservative and the solid preservative powder to obtain the fruit preservative. The invention is natural and green, has good preservation effects, is safe and non-toxic, is simple to operate, and is low in cost. Most of the above-mentioned existing technologies have improved their overall structure. However, during use, existing solid preservatives are unable to effectively inhibit the physiological metabolism of fruits, produce ethylene, and kill pathogens at the same time, resulting in a short shelf life of fruits. Traditional preservatives (such as sulfur dioxide and nitrites) have the risk of chemical residues and uncontrollable release rates, which can easily lead to excessive concentrations in the early stage or failure in the later stage, and have certain limitations. Summary of the Invention

[0003] The object of the present invention is to provide a method for preparing a sustained-release solid preservative to solve the problems raised in the above-mentioned background art, namely, the inability to effectively inhibit the physiological metabolism of fruits, the production of ethylene, and the killing of pathogens at the same time, resulting in a short shelf life of fruits, and the risk of chemical residues caused by traditional preservatives (such as sulfur dioxide and nitrites) and the uncontrollable release rate, which easily lead to excessive concentration in the early stage or failure in the later stage.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a sustained-release solid preservative, comprising a preservative, wherein the preservative is made from the following raw materials in parts by weight: 5-8 parts of chitosan, 2-4 parts of carrageenan, 1-5 parts of sodium citrate, 2-3 parts of silicon dioxide, 3-4 parts of 1-methylcyclopropene, 2-3 parts of chlorine dioxide, 1-2 parts of water, and 3-6 parts of baking soda.

[0005] Further preferably, the weight portion of the chitosan is 6-7 parts, the weight portion of the carrageenan is 3 parts, the weight portion of the sodium citrate is 3-4 parts, the weight portion of the silicon dioxide is 2.5 parts, the weight portion of the 1-methylcyclopropene is 3.5 parts, the weight portion of the chlorine dioxide is 2.5 parts, the weight portion of the water is 1.5 parts, and the weight portion of the baking soda is 3-6 parts.

[0006] Further preferably, the preparation method of the preservative comprises the following steps: S1: taking out chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene and chlorine dioxide respectively according to the ratio; S2: putting chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, chlorine dioxide and water in the corresponding ratio into a granulator for granulation, and controlling the temperature of the granulator at 20-40°C to form solid particles.

[0007] Further preferably, the granulation conditions of the granulator are as follows: the temperature is controlled at 20-40° C., the rotation speed is 20-50 r / min, the granulation time is 10-30 min, and the granulator granulates to prepare solid particles.

[0008] More preferably, the solid particles are soaked in a baking soda solution for 30-60 minutes, and then placed in an oven to dry for 1-12 hours to obtain a solid preservative.

[0009] More preferably, the solid preservative is placed in a non-woven bag and placed in a sealed foam box or packaging bag for transporting the fruit. The preservative effectively releases carbon dioxide, 1-methylcyclopropene, and chlorine dioxide, while simultaneously inhibiting the physiological metabolism of the fruit, the production of ethylene, and killing pathogens, thereby extending the shelf life of the fruit. More preferably, the fruit is a climacteric or non-climacteric fruit.

[0010] More preferably, the chitosan has a deacetylation degree of ≥50% and a molecular weight of 50,000-300,000 Da.

[0011] Further preferably, the method further comprises the following steps: (a) acid-modifying the formed solid preservative; (b) dissolving the antibacterial agent and the antioxidant in an ethanol-water solution, and ultrasonically loading the antibacterial agent and the antioxidant onto the solid preservative; (c) coating the surface of the solid preservative with an ethyl cellulose-propolis composite film using a fluidized bed spraying technique; and (d) adding an adhesive and pressing the solid preservative into shape.

[0012] Further preferably, the solid preservative is immersed in a 5% citric acid solution, ultrasonically treated at 60°C for 2h, washed until neutral, and dried at 110°C; an ethanol-water (1:1 v / v) mixed solution is prepared, and the active ingredient is added to dissolve; the activated carrier is immersed in the solution (solid-liquid ratio 1:5), ultrasonicated at 40kHz for 30min, and vacuum dried at 60°C; ethyl cellulose and propolis (mass ratio 9:1) are dissolved in acetone and spray-coated in a fluidized bed (inlet air temperature 50°C, atomization pressure 0.2MPa); Add 5% hydroxypropyl methylcellulose (HPMC) as a binder and press into tablets with a diameter of 5mm and a thickness of 2mm, or granulate into 20-40 mesh particles. Use acid-modified solid preservatives to load natural antibacterial / antioxidant ingredients and coat with a pH-responsive ethyl cellulose-propolis composite film to achieve environmentally adaptive and controlled release of active ingredients. This preservative is long-lasting and safe, and can extend the storage period of respiratory climacteric fruits to 21 days and the shelf life of non-respiratory climacteric fruits to 15 days, significantly reducing the loss rate of fresh food.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The method for preparing a sustained-release solid preservative comprises placing 5-8 parts of chitosan, 2-4 parts of carrageenan, 1-5 parts of sodium citrate, 2-3 parts of silicon dioxide, 3-4 parts of 1-methylcyclopropene, 2-3 parts of chlorine dioxide, and 1-2 parts of water into a granulator for granulation to prepare solid particles, then soaking the solid particles in a solution of 3-6 parts of baking soda, and then drying to obtain the solid preservative. The solid preservative is placed in a non-woven bag and placed in a sealed foam box or packaging bag for fruit transportation. The preservative releases carbon dioxide, 1-methylcyclopropene, and chlorine dioxide, while effectively inhibiting the physiological metabolism of the fruit, the production of ethylene, and killing pathogens, thereby extending the shelf life of the fruit. Furthermore, by loading natural antibacterial / antioxidant ingredients into an acid-modified solid preservative and coating it with a pH-responsive ethyl cellulose-propolis composite film, the environmentally adaptive and controllable release of active ingredients is achieved. This preservative is long-lasting and safe, and can extend the storage period of respiratory climacteric fruits to 21 days and the shelf life of non-respiratory climacteric fruits to 15 days, significantly reducing the loss rate of fresh food and improving overall practicality. DETAILED DESCRIPTION

[0014] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0015] Example 1: The present invention provides the following technical solution: A method for preparing a sustained-release solid preservative, comprising a preservative, wherein the preservative is made of the following raw materials in parts by weight: chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, chlorine dioxide and water.

[0016] The weight portion of the chitosan is 6 parts, the weight portion of the carrageenan is 3 parts, the weight portion of the sodium citrate is 3 parts, the weight portion of the silicon dioxide is 2.5 parts, the weight portion of the 1-methylcyclopropene is 3.5 parts, the weight portion of the chlorine dioxide is 2.5 parts, the weight portion of the water is 1.5 parts; the weight portion of the baking soda is 4 parts; The preparation method of the preservative comprises the following steps: S1: Chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, and chlorine dioxide are weighed according to the respective proportions; S2: Chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, chlorine dioxide, and water in the corresponding proportions are placed in a granulator for granulation to obtain solid granules; S3: The solid granules are soaked in a baking soda solution and then dried to obtain a solid preservative. The chitosan has a degree of deacetylation of ≥50% and a molecular weight of 50,000-300,000 Da. The granulation conditions of the granulator are as follows: a temperature of 20-40°C, a rotation speed of 20-50 rpm, a granulation time of 10-30 minutes, a soaking time of 30-60 minutes, and a drying time of 1-12 hours. The solid preservative is packed in a non-woven bag and is used to preserve the fruit in sealed foam boxes or packaging bags during fruit transportation. The fruit is a respiratory climacteric type or a non-respiratory climacteric type fruit. The preservative can release carbon dioxide, 1-methylcyclopropene and chlorine dioxide, while effectively inhibiting the physiological metabolism of the fruit, the production of ethylene and killing pathogens, thereby extending the shelf life of the fruit.

[0017] Example 2: The weight parts of the chitosan are 5 parts, the weight parts of the carrageenan are 2 parts, the weight part of the sodium citrate is 1 part, the weight parts of the silicon dioxide are 2 parts, the weight parts of the 1-methylcyclopropene are 3 parts, the weight parts of the chlorine dioxide are 2 parts, the weight part of the water is 1 part; the weight part of the baking soda is 5 parts; The preparation method of the preservative comprises the following steps: S1: Chitosan, carrageenan, sodium citrate, silica, 1-methylcyclopropene, and chlorine dioxide are prepared according to the respective proportions. S2: Chitosan, carrageenan, sodium citrate, silica, 1-methylcyclopropene, chlorine dioxide, and water are placed in a granulator for granulation to obtain solid granules. S3: The solid granules are soaked in a baking soda solution and then dried to obtain a solid preservative. The chitosan has a degree of deacetylation of ≥50% and a molecular weight of 50,000-300,000 Da. The granulation conditions of the granulator are as follows: a temperature of 20-40°C, a rotation speed of 20-50 rpm, a granulation time of 10-30 minutes, a soaking time of 30-60 minutes, and a drying time of 1-12 hours. The solid preservative is packed in a non-woven bag and is used to preserve the fruit in sealed foam boxes or packaging bags during fruit transportation. The fruit is a climacteric or non-climacteric type. The preservative releases carbon dioxide, 1-methylcyclopropene and chlorine dioxide, while effectively inhibiting the physiological metabolism of the fruit, the production of ethylene and killing pathogens, thereby extending the shelf life of the fruit.

[0018] Example 3: The weight parts of the chitosan are 8 parts, the weight parts of the carrageenan are 4 parts, the weight parts of the sodium citrate are 5 parts, the weight parts of the silicon dioxide are 3 parts, the weight parts of the 1-methylcyclopropene are 4 parts, the weight parts of the chlorine dioxide are 3 parts, the weight parts of the water are 2 parts; the weight parts of the baking soda are 6 parts; The preparation method of the preservative comprises the following steps: S1: Chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, and chlorine dioxide are taken out according to the respective proportions; S2: Chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, chlorine dioxide, and water in the corresponding proportions are placed in a granulator for granulation to obtain solid preservative granules; S3: The solid granules are soaked in a baking soda solution and then dried to obtain the solid preservative. The temperature of the granulator is controlled at 20-40°C, the degree of deacetylation of the chitosan is ≥50%, and the molecular weight is 50,000-300,000 Da. The granulation conditions of the granulator are as follows: temperature controlled at 20-40°C, rotation speed of 20-50 r / min, granulation time of 10-30 minutes, soaking time of 30-60 minutes, and drying time of 1-12 hours. The solid preservative is packed in a non-woven bag and is used to preserve the fruit in sealed foam boxes or packaging bags during fruit transportation. The fruit is a climacteric or non-climacteric type. The preservative releases carbon dioxide, 1-methylcyclopropene and chlorine dioxide slowly, while effectively inhibiting the physiological metabolism of the fruit, the production of ethylene and killing pathogens, thereby extending the shelf life of the fruit.

[0019] Example 4: The weight parts of the chitosan are 7.5 parts, the weight parts of the carrageenan are 3.5 parts, the weight parts of the sodium citrate are 4.5 parts, the weight parts of the silicon dioxide are 2.5 parts, the weight parts of the 1-methylcyclopropene are 3.5 parts, the weight parts of the chlorine dioxide are 2.5 parts, the weight parts of the water are 1.8 parts; the weight parts of the baking soda are 3.5 parts; The preparation method of the preservative comprises the following steps: S1: Chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, and chlorine dioxide are taken out according to the respective proportions; S2: Chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, chlorine dioxide, and water in the corresponding proportions are placed in a granulator for granulation to obtain solid preservative granules; S3: The solid granules are soaked in a baking soda solution and then dried to obtain the solid preservative. The temperature of the granulator is controlled at 20-40°C to form a solid preservative, wherein the chitosan has a deacetylation degree of ≥50% and a molecular weight of 50,000-300,000 Da. The granulation conditions of the granulator are as follows: a temperature of 20-40°C, a rotation speed of 20-50 r / min, a granulation time of 10-30 minutes, a soaking time of 30-60 minutes, and a drying time of 1-12 hours. The solid preservative is packed in a non-woven bag and is used to preserve the fruit in sealed foam boxes or packaging bags during fruit transportation. The fruit is a climacteric or non-climacteric type. The preservative releases carbon dioxide, 1-methylcyclopropene and chlorine dioxide, while effectively inhibiting the physiological metabolism of the fruit, the production of ethylene and killing pathogens, thereby extending the shelf life of the fruit.

[0020] Example 5: Based on Example 1, the following steps are also included: (a) Acid modification of a molded solid preservative; (b) Dissolving an antimicrobial agent and an antioxidant in an ethanol-water solution and ultrasonically loading them onto the solid preservative; (c) Coating the solid preservative with an ethyl cellulose-propolis composite film using a fluidized bed spray technique; (d) Adding an adhesive and performing compression molding.

[0021] The solid preservative was immersed in a 5% citric acid solution, ultrasonically treated at 60°C for 2 hours, washed until neutral, and dried at 110°C. An ethanol-water (1:1 v / v) mixed solution was prepared, and the active ingredient was added to dissolve it. The activated carrier was immersed in the solution (solid-to-liquid ratio 1:5), ultrasonicated at 40kHz for 30 minutes, and vacuum-dried at 60°C. Ethyl cellulose and propolis (mass ratio 9:1) were dissolved in acetone and spray-coated using a fluidized bed (inlet air temperature 50°C, atomization pressure 0.2 MPa). 5% hydropropyl methylcellulose (HPMC) was added as a binder and pressed into tablets with a diameter of 5 mm and a thickness of 2 mm, or granulated into 20-40 mesh particles. The acid-modified solid preservative was loaded with natural antibacterial / antioxidant ingredients and coated with a pH-responsive ethyl cellulose-propolis composite film to achieve environmentally adaptive and controllable release of the active ingredients. This long-lasting and safe preservative can extend the storage life of climacteric fruits to 21 days and the shelf life of non-climacteric fruits to 15 days, significantly reducing the loss rate of fresh food.

[0022] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0023] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a sustained-release solid preservative, comprising a preservative, characterized in that: The preservative is prepared from the following raw materials in parts by weight: 5-8 parts of chitosan, 2-4 parts of carrageenan, 1-5 parts of sodium citrate, 2-3 parts of silicon dioxide, 3-4 parts of 1-methylcyclopropene, 2-3 parts of chlorine dioxide, 1-2 parts of water and 3-5 parts of baking soda.

2. The method for preparing a sustained-release solid preservative according to claim 1, characterized in that: The weight portion of the chitosan is 6-7 parts, the weight portion of the carrageenan is 3 parts, the weight portion of the sodium citrate is 3-4 parts, the weight portion of the silicon dioxide is 2.5 parts, the weight portion of the 1-methylcyclopropene is 3.5 parts, the weight portion of the chlorine dioxide is 2.5 parts, the weight portion of the water is 1.5 parts, and the weight of the baking soda is 3-6 parts.

3. The method for preparing a sustained-release solid preservative according to claim 1, characterized in that: The preparation method of the preservative comprises the following steps: S1: Weigh chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, chlorine dioxide, water, and baking soda according to the ratio; S2: Chitosan, carrageenan, sodium citrate, silicon dioxide, 1-methylcyclopropene, chlorine dioxide, and water in corresponding proportions are placed in a granulator at a temperature of 20-40°C to form solid granules. The solid granules are then soaked in a baking soda solution for 30-60 minutes, then dried in an oven for 1-12 hours to obtain a solid preservative.

4. The method for preparing a sustained-release solid preservative according to claim 3, wherein: The granulation conditions of the granulator are as follows: temperature controlled at 20-40° C., rotation speed at 20-50 r / min, granulation time at 10-30 min, soaking at 30-60 min, and drying at 1-12 h.

5. The method for preparing a sustained-release solid preservative according to claim 4, characterized in that: The solid preservative is packed in a non-woven bag, placed in a foam box or packaging bag for fruit storage or transportation and sealed, thereby playing the role of fruit freshness preservation.

6. The method for preparing a sustained-release solid preservative according to claim 5, characterized in that: The preservative releases carbon dioxide, 1-methylcyclopropene and chlorine dioxide, while effectively inhibiting the physiological metabolism of fruits, the production of ethylene and killing pathogens, thereby extending the shelf life of fruits.

7. The method for preparing a sustained-release solid preservative according to claim 5, characterized in that: The fruits are climacteric and non-climacteric fruits.

8. The method for preparing a sustained-release solid preservative according to claim 6, characterized in that: The chitosan has a deacetylation degree of ≥50% and a molecular weight of 50,000-300,000 Da.

9. The method for preparing a sustained-release solid preservative according to claim 7, characterized in that: The following steps are also included: (a) subjecting the formed solid preservative to acid modification treatment; (b) dissolving the antibacterial agent and the antioxidant in an ethanol-water solution and loading them onto a solid preservative with the aid of ultrasound; (c) coating the surface of the solid preservative with an ethyl cellulose-propolis composite film using a fluidized bed spraying technique; (d) Adding a binder and pressing into shape.

10. The method for preparing a sustained-release solid preservative according to claim 8, characterized in that: The solid preservative was immersed in a 5% citric acid solution, ultrasonically treated at 60°C for 2 hours, washed until neutral, and dried at 110°C; Prepare an ethanol-water (1:1 v / v) mixed solution and add the active ingredient to dissolve; The activated support was immersed in the solution (solid-to-liquid ratio 1:5), ultrasonicated at 40 kHz for 30 min, and dried in a vacuum at 60 °C; Ethyl cellulose and propolis (mass ratio 9:1) were dissolved in acetone and spray-coated using a fluidized bed (inlet air temperature 50 °C, atomization pressure 0.2 MPa); Add 5% hydroxypropyl methylcellulose (HPMC) as a binder and press into tablets with a diameter of 5 mm and a thickness of 2 mm, or granulate into 20-40 mesh particles.