Preservative with function of prolonging shelf life of fruits and vegetables

Abstract

The invention discloses a preservative with an effect of prolonging the shelf life of fruits and vegetables. The fresh-keeping agent is prepared from the following raw material components in percentage by weight: 3 to 5 percent of essential oil microcapsules, 0.1 to 0.5 percent of 1-methylcyclopropene, 0.5 to 1.5 percent of sodium alginate, 0.01 to 0.05 percent of citric acid, 0.1 to 0.5 percent of calcium chloride, 0.1 to 0.4 percent of glycerol, 0.01 to 0.05 percent of tween-80 and the balance of water. According to the present invention, the prepared fresh-keeping agent is uniformly coated on the fruit body in the fruit soaking manner, such that the protection layer can be formed on the surface of the fruit body, the protection layer is isolated from the outside, the disease invasion can be prevented, the water evaporation can be reduced, the sterilization effect can be provided, the fruit wilting and rotting can be prevented, the ethylene generation can be inhibited, and the shelf life of the fruit and vegetable can be well prolonged. The fresh-keeping agent is prepared from natural raw materials which are free of residues after being used, is free of harmful substances, not only is good in fresh-keeping effect, but also is safe and non-toxic, and consumers can eat the fresh-keeping agent at ease.

Description

Technical Field

[0001] The invention relates to the technical field of fruit and vegetable preservation, and in particular to a preservative capable of extending the shelf life of fruits and vegetables. Background Art

[0002] Fruits and vegetables are the main components of the diet of Chinese residents. They are rich in a variety of essential nutrients for the human body, such as vitamins, inorganic salts and dietary fiber. However, due to their strong seasonality, regionality and perishability, if the storage capacity is poor and the preservation technology is backward, serious losses will inevitably occur. After harvest, fruits and vegetables are still living organisms, with complex life activities such as dormancy, water evaporation and respiration. These activities are closely related to the preservation of fruits and vegetables, affecting and restricting their storage life.

[0003] As we all know, ethylene has the effect of promoting the ripening and aging of fruits and vegetables, so most post-harvest treatment measures focus on controlling the ethylene production of fruits and vegetables. There are many inhibitors for controlling ethylene production in production, such as aminooxyacetic acid (AOA), salicylic acid (SA), 2,5-NBD, silver thiosulfate (STS), aminooxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP). Among them, 1-MCP can inhibit the binding of ethylene receptors of fruits and vegetables to ethylene, thereby slowing down the ripening of fruits and vegetables, thereby extending the shelf life of fruits and vegetables, and has the advantages of non-toxicity, low concentration, high efficiency and easy operation, so it is widely used. In recent years, many studies have found that most natural plant essential oils have good antibacterial and antioxidant activities, and since essential oils usually refer to volatile aromatic substances extracted from plant tissues, they are safe and edible, so the use of natural plant essential oils and 1-methylcyclopropene to prepare preservatives to improve the preservation effect of fruits and vegetables has attracted widespread attention.

[0004] CN115669675A A fruit quality control preservative and a method of use, the invention fruit quality control preservative comprises quality control agent 1, quality control agent 2 and preservative 3; quality control agent 1 comprises imidacloprid, carvacrol, prohexadione calcium and aminoethyl ester; quality control agent 2 comprises food grade potassium pyrosulfate, matrine, prohexadione calcium and peppermint essential oil; preservative 3 comprises 1-methylcyclopropene and acetylsalicylic acid. The invention combines two quality control agents with preservatives and uses them successively, which plays a good role in quality control and preservation. However, the peppermint essential oil in the fruit quality control preservative has strong volatility, and its main components such as menthol and menthone are sensitive to air, sunlight and temperature, which easily leads to rapid loss of effective components during long-term storage or use, and it is difficult to form a sustained and stable antibacterial and antioxidant protective film on the surface of the fruit, which is not conducive to long-term preservation.

[0005] In order to achieve long-term preservation of essential oils, they need to be loaded or embedded. Currently, the emulsion method is commonly used to embed essential oils in hydrophilic polymers and dry them into thin films; or essential oils are mixed with polymers such as starch in the solid state, extruded through a screw extruder, sieved, and made into powder. However, most existing methods have disadvantages in the preparation of solid composites. The amount of essential oil volatilization loss is large, which makes it difficult to control the content of embedded essential oils and increases the cost due to the loss of essential oils. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, the present invention provides a preservative having the function of extending the shelf life of fruits and vegetables. The preservative of the present invention comprises essential oil microcapsules, sodium alginate, 1-methylcyclopropene, citric acid, calcium chloride, glycerol, Tween-80 and water, and the raw material components are reasonably proportioned and used in synergy to achieve the purpose of extending the shelf life of fruits and vegetables, and the essential oil components are protected by forming essential oil microcapsules, so as to protect the essential oil components from the influence of the external environment, and at the same time, the essential oil is slowly released to achieve the effect of long-term preservation.

[0007] To achieve the above object, the present invention provides a preservative with the function of extending the shelf life of fruits and vegetables, which comprises, by weight percentage, 3-5% essential oil microcapsules, 0.1-0.5% 1-methylcyclopropene, 0.5-1.5% sodium alginate, 0.01-0.05% citric acid, 0.1-0.5% calcium chloride, 0.1-0.4% glycerol, 0.01-0.05% Tween-80, and the balance is water.

[0008] Preferably, the 1-methylcyclopropene is in the form of microcapsule granules, wherein the 1-methylcyclopropene content is 1-5%.

[0009] Preferably, the method for preparing the essential oil microcapsules comprises the following steps, measured by weight:

[0010] 10-20 parts of the carrier are added to 20-40 parts of water, and then mixed and stirred at 40-60°C and 10000-13000 rpm for 10-20 minutes to obtain a capsule wall material dispersion 1; 3-8 parts of essential oil are added to the capsule wall material dispersion 1, and then stirred and emulsified at 15000-20000 rpm for 20-30 minutes to obtain an emulsion a; 10-20 parts of maltodextrin are added to 30-70 parts of water, and then mixed and stirred at 50-60°C and 800-1000 rpm; The mixture was stirred for 5-10 minutes to obtain a capsule wall material dispersion 2; emulsion a was added to the capsule wall material dispersion 2, and then stirred and mixed at 12000-18000 rpm for 5-10 minutes to obtain emulsion b; emulsion b was subjected to high-pressure homogenization for 2-3 times at a homogenization pressure of 35-40 MPa to form a fine and uniform emulsion, and then spray-dried at an atomization pressure of 1-1.5 MPa, an inlet air temperature of 160-190° C., and an outlet air temperature of 75-85° C. to obtain essential oil microcapsules.

[0011] Preferably, the essential oil is selected from one or more combinations of cumin essential oil, oregano essential oil and white mustard volatile oil.

[0012] Further preferably, the essential oil is formed by mixing cumin essential oil, oregano essential oil and white mustard volatile oil in a mass ratio of 1-2:1-2:1-2.

[0013] Preferably, the carrier is selected from plant starch, angustifolia gum, or a combination of both.

[0014] Further preferably, the carrier is a mixture of plant starch and angustifolia gum in a mass ratio of 1:1-3.

[0015] Preferably, the plant starch is selected from at least one of mango kernel starch and modified mango kernel starch.

[0016] Preferably, the method for preparing mango kernel starch comprises the following steps:

[0017] The mango kernel is washed, dried and crushed to obtain mango kernel powder, and then the mango kernel powder is mixed with a sodium pyrosulfite aqueous solution with a concentration of 0.15-0.2wt% in a mass ratio of 1:2-10, and soaked for 12-24 hours to obtain a slurry; the obtained slurry is passed through a 100-200 mesh sieve, and then through a 200-300 mesh sieve, and then settled, the supernatant is decanted, the starch layer is resuspended in water, and then centrifuged at 7000-9000rpm for 4-8min, the upper non-white layer is discarded, the lower starch layer is resuspended in water, and then centrifuged again at 7000-9000rpm for 5-8min, the supernatant is discarded, and a white starch precipitate is collected; the obtained starch precipitate is dried in a hot air oven at 40-50℃, and then crushed and passed through a 100-200 mesh sieve to obtain mango kernel starch.

[0018] Preferably, the preparation method of the modified mango kernel starch comprises the following steps:

[0019] The mango kernel is washed, dried and crushed to obtain mango kernel powder, and then the mango kernel powder is mixed with a sodium metabisulfite aqueous solution with a concentration of 0.15-0.2wt% in a mass ratio of 1:2-10, and soaked for 12-24 hours to obtain a slurry; the obtained slurry is passed through a 100-200 mesh sieve, and then through a 200-300 mesh sieve, and then settled, the supernatant is decanted, the starch layer is resuspended in water, and then centrifuged at 7000-9000rpm for 4-8min, the upper non-white layer is discarded, and the lower starch layer is resuspended in water, and then centrifuged again at 7000-9000rpm for 5-8min, the supernatant is discarded, and the white starch precipitate is collected; the obtained starch precipitate is dried in a hot air oven at 40-50℃, and then crushed for 1 The invention relates to a method for preparing mango kernel starch by sieve through a 00-200 mesh sieve to obtain mango kernel starch; mixing the mango kernel starch with water in a mass ratio of 1:5-8 to form a suspension, and dripping a 1-2wt% hydrogen peroxide aqueous solution into the suspension under continuous stirring at 400-600rpm, and reacting at 28-35°C for 1-3h, wherein the mass ratio of the hydrogen peroxide aqueous solution to the starch is 3-7:100; then adding a 0.5-1mol / L sodium hydroxide aqueous solution to adjust the pH to 7-8, filtering, collecting starch precipitates, washing 3-4 times with water 3-5 times the total mass of the starch precipitates, and finally washing 1-2 times with a 90-95wt% ethanol aqueous solution 3-5 times the total mass of the starch precipitates, and drying at 40-50°C for 22-25h to obtain modified mango kernel starch.

[0020] Elaeagnus angustifolia gum is a Chinese medicinal material, derived from the gum exuded from the stems and branches of the Elaeagnus angustifolia plant, with good thickening, emulsification, film-forming and adhesion, while mango kernel starch has high swelling and solubility, and the two have different chemical structures and physical properties. The inventors found that the two can be used in coordination as essential oil microcapsule wall materials, not only can the respective performances be complemented, forming a more uniform and more stable microcapsule wall, but also can improve the mechanical strength and toughness of the microcapsules, making it more tolerant to physical pressure during storage and transportation, reducing the rupture of the microcapsules, and ensuring the sustained release of essential oils. At the same time, the elaeagnus angustifolia gum and mango kernel starch are used in coordination as essential oil microcapsule wall materials, and may have better compatibility with the essential oil components during the preparation process, which helps to improve the dispersibility and uniformity of the essential oils in the microcapsules, improve the embedding efficiency and release control of the essential oils, ensure that the effective ingredients of the essential oils can be evenly distributed on the surface of fruits and vegetables, improve the fresh-keeping effect, and realize the slow release of the essential oils, so as to play a long-term fresh-keeping effect.

[0021] The inventors have found that oxidative modification of mango kernel starch can reduce the retrogradation phenomenon of mango kernel starch, that is, the tendency of starch gel to reform a crystalline structure after cooling. Reducing the retrogradation phenomenon helps to maintain the structural integrity of the microcapsules, avoiding hardening or rupture of the microcapsules caused by starch retrogradation during storage, thereby affecting the preservation effect of the preservative. In addition, the oxidatively modified mango kernel starch may have better solubility and swelling capacity than mango kernel starch, which helps to form a uniform emulsion when mixed with angustifolia gum during the preparation process, and then form stable microcapsules during the spray drying process. This stability is conducive to maintaining the encapsulation efficiency of essential oils and extending the shelf life of fruits and vegetables.

[0022] The present invention also provides a method for preparing the above-mentioned preservative having the function of extending the shelf life of fruits and vegetables, comprising the following steps:

[0023] According to weight percentage, 3-5% essential oil microcapsules, 0.5-1.5% sodium alginate, 0.01-0.05% citric acid, 0.1-0.5% calcium chloride, 0.1-0.4% glycerol, 0.01-0.05% Tween-80, 0.1-0.5% 1-methylcyclopropene and the balance water are mixed evenly to obtain a preservative.

[0024] In the preservative of the present invention, sodium alginate can form a hydrogel to form a coating on the surface of fruits and vegetables, thereby blocking oxygen and moisture, and also inhibiting the infection of fruits and vegetables by microorganisms to a certain extent, and having a certain antibacterial effect. In addition, the sodium alginate coating can also slow down the respiration of fruits and vegetables, reduce the decay of fruits and vegetables, and extend the shelf life.

[0025] In the preservative of the present invention, cumin essential oil is a volatile aromatic oil with a strong odor extracted from cumin (Cuminum cyminum L.) seeds, and its main components include cuminaldehyde, cuminone, cuminol, cuminaldehyde, etc., and also contain some terpenoid compounds such as γ-terpinene, etc. Cumin essential oil has a strong inhibitory effect on a variety of post-harvest pathogenic fungi of fruits and vegetables such as Penicillium, Fusarium, Candida albicans, late blight fungi, Rhizopus stolonifera, etc., and can effectively reduce the rot and deterioration of fruits and vegetables caused by microbial infection. And it contains a variety of antioxidant active ingredients, which can play an antioxidant effect by reducing the respiration rate, reducing the accumulation of free radicals, chelating metal ions, inhibiting lipid peroxidation, regulating antioxidant enzyme activity and antioxidant content, etc., delaying the oxidative aging of fruits and vegetables, maintaining the color, flavor and nutritional components of fruits and vegetables, and extending the shelf life of fruits and vegetables. In addition, it can also inhibit the respiration of fruits and vegetables, reduce the respiratory intensity, reduce the consumption of nutrients inside fruits and vegetables, thereby delaying the aging process of fruits and vegetables.

[0026] In the preservative of the present invention, oregano essential oil is a volatile oily liquid with a strong herbal aroma extracted from oregano (Origanum vulgare L.), a plant of the genus Origanum of the Lamiaceae family. Its main components include phenolic compounds such as carvacrol and thymol, and also contain terpene compounds, such as γ-terpinene, p-isopropylbenzyl alcohol, etc. Oregano essential oil has a significant inhibitory effect on a variety of fruit and vegetable pathogens, and the carvacrol and thymol it contains can destroy the cell membrane structure of the pathogen, causing leakage of intracellular substances, thereby inhibiting the growth and reproduction of the pathogen, so in the fresh-keeping process, can effectively reduce the decay phenomenon of fruits and vegetables caused by microbial infection. And the components in the oregano essential oil have antioxidant properties, can remove the free radicals produced by fruits and vegetables during metabolism, can delay the aging process of fruits and vegetables, and keep the color and texture of fruits and vegetables. In addition, it can also affect the metabolism of fruit and vegetable cell walls, maintain the integrity of cell walls by inhibiting the activity of cell wall degrading enzymes, thereby maintaining the hardness of fruits and vegetables, preventing fruits and vegetables from softening and deforming, and extending the shelf life of fruits and vegetables.

[0027] In the preservative of the present invention, the white mustard volatile oil is mainly extracted from the seeds (white mustard) of the cruciferous plant white mustard (Sinapis alba L.), and its components mainly include allyl isothiocyanate and some terpenoid compounds, such as α-pinene, β-pinene, etc. The allyl isothiocyanate in the white mustard volatile oil has significant antibacterial activity, and has a strong inhibitory effect on a variety of pathogens that cause fruit and vegetable rot, such as fungi such as penicillium, aspergillus, and root mold, and can prevent the growth and reproduction of pathogens. In the process of fruit and vegetable preservation, the use of a preservative containing white mustard volatile oil can effectively reduce the infringement of microorganisms on fruits and vegetables and reduce the rot rate of fruits and vegetables. In addition, terpenoid compounds and other ingredients in white mustard volatile oil have antioxidant properties, which can scavenge free radicals produced during the storage of fruits and vegetables, reduce oxidative damage, delay the aging of fruits and vegetables, and extend their shelf life. In addition, white mustard volatile oil can also regulate the respiration of fruits and vegetables, reduce the respiration intensity, thereby reducing the material consumption inside fruits and vegetables and extending the shelf life of fruits and vegetables.

[0028] Beneficial effects of the present invention:

[0029] 1. Compared with the prior art, the preservative provided by the present invention is prepared from essential oil microcapsules, sodium alginate, 1-methylcyclopropene, citric acid, calcium chloride, glycerol, Tween-80 and water in a certain ratio. The preservative prepared by the present invention is prepared by selecting natural raw materials that have no residue after use, and does not contain harmful substances. It not only has a good preservative effect, but is also safe and non-toxic, and consumers can eat it with confidence. The preservative of the present application is evenly coated on the fruit body in the form of soaking the fruit, which can form a protective layer on the surface of the fruit body, isolate it from the outside world, prevent disease invasion, reduce water evaporation, and play a bactericidal role at the same time, prevent the fruit from wilting and rotting, and can inhibit the production of ethylene, which can well extend the shelf life of fruits and vegetables.

[0030] 2. Compared with the prior art, the present invention selects galangal gum and mango kernel starch or modified mango kernel starch as microcapsule wall materials to mix with essential oil components, and is used in coordination with maltodextrin, and is prepared by high pressure homogenization and atomization drying methods to obtain essential oil microcapsules, and the essential oil components are protected by forming the form of essential oil microcapsules, and the essential oil components are protected from the influence of the external environment (such as light, oxygen, heat), and the release rate of the essential oil is controlled at the same time, so that the essential oil is slowly released during storage, and the validity period of the essential oil is extended, thereby maintaining the long-term stability and biological activity of the essential oil, which is conducive to improving the fruit and vegetable preservation effect of the preservative. The active ingredients such as cumin essential oil, oregano essential oil, and white mustard volatile oil contained in the essential oil microcapsules have antibacterial and antioxidant properties, can inhibit microbial growth, reduce oxidative damage, delay the aging of fruits and vegetables, and can regulate the respiration of fruits and vegetables, by reducing the respiratory intensity, thereby reducing the material consumption inside fruits and vegetables, extending the shelf life of fruits and vegetables, thereby extending the shelf life of fruits and vegetables. DETAILED DESCRIPTION

[0031] Parameters for specific chemical substances used, sources.

[0032] 1-Methylcyclopropene, dosage form: microcapsule granules, content: 3.3%, brand: Dr. Fresh;

[0033] Mango pits, no special requirements, commercially available;

[0034] Maltodextrin, product number: S11157, from Shanghai Yuanye Biotechnology Co., Ltd.;

[0035] Cumin essential oil, item number: S29819, from Shanghai Yuanye Biotechnology Co., Ltd.;

[0036] Oregano essential oil, item number: S27449, from Shanghai Yuanye Biotechnology Co., Ltd.;

[0037] The preparation method of white mustard volatile oil is as follows: weigh white mustard (commercially available), crush it, and place it in a round-bottom flask; add 5 times the amount of disodium hydrogen phosphate-citric acid buffer solution with a pH of 5, shake it evenly, and then add ascorbic acid to a concentration of 0.5 mmol / L; place it in 50°C constant temperature water for hydrolysis for 3 hours, then add 4 times the amount of water and extract it by steam distillation to obtain white mustard volatile oil, which is a light yellow oily substance, that is, white mustard volatile oil;

[0038] Preparation method of Elaeagnus angustifolia gum: Elaeagnus angustifolia gum is collected from August to September every summer. 100 kg of the collected Elaeagnus angustifolia gum is naturally dried in a cool place and then crushed with a grinder for 120 seconds. A 100-mesh round stainless steel sieve is used to filter the impurities to obtain gum powder, that is, Elaeagnus angustifolia gum.

[0039] Example 1

[0040] A method for preparing a preservative capable of extending the shelf life of fruits and vegetables comprises the following steps:

[0041] According to weight percentage, 4% essential oil microcapsules, 0.3% 1-methylcyclopropene, 1.5% sodium alginate, 0.03% citric acid, 0.3% calcium chloride, 0.3% glycerol, 0.03% Tween-80 and the balance water are mixed evenly to obtain a preservative.

[0042] The preparation method of the essential oil microcapsules comprises the following steps:

[0043] Add 15 parts by weight of galangal gum to 35 parts by weight of water, and then stir at 50°C and 12000 rpm for 15 minutes to obtain capsule wall material dispersion 1; add 6 parts by weight of essential oil to the above-mentioned capsule wall material dispersion 1, and then stir and emulsify at 18000 rpm for 25 minutes to obtain emulsion a; add 15 parts by weight of maltodextrin to 50 parts by weight of water, and then stir and mix at 50°C and 900 rpm for 8 minutes to obtain capsule wall material dispersion 2; add emulsion a to the above-mentioned capsule wall material dispersion 2, and then stir and mix at 15000 rpm for 8 minutes to obtain emulsion b; high-pressure homogenize emulsion b at a homogenization pressure of 38 MPa for 3 times to form a fine and uniform emulsion, and then spray-dry at an atomization pressure of 1.2 MPa, an inlet air temperature of 180°C, and an outlet air temperature of 82°C to obtain essential oil microcapsules.

[0044] The essential oil is prepared by mixing cumin essential oil, oregano essential oil and white mustard volatile oil in a mass ratio of 2:1:1.

[0045] Example 2

[0046] A method for preparing a preservative having the function of extending the shelf life of fruits and vegetables, which is different from Example 1 in that the method for preparing the essential oil microcapsules comprises the following steps:

[0047] 15 parts by weight of mango kernel starch are added to 35 parts by weight of water, and then mixed and stirred at 50°C and 12000 rpm for 15 minutes to obtain a capsule wall material dispersion 1; 6 parts by weight of essential oil are added to the above-mentioned capsule wall material dispersion 1, and then stirred and emulsified at 18000 rpm for 25 minutes to obtain emulsion a; 15 parts by weight of maltodextrin are added to 50 parts by weight of water, and then mixed and stirred at 50°C and 900 rpm for 8 minutes to obtain a capsule wall material dispersion 2; emulsion a is added to the above-mentioned capsule wall material dispersion 2, and then stirred and mixed at 15000 rpm for 8 minutes to obtain emulsion b; emulsion b is subjected to high-pressure homogenization 3 times under the condition of a homogenization pressure of 38 MPa to form a fine and uniform emulsion, and then spray-dried under the conditions of an atomization pressure of 1.2 MPa, an air inlet temperature of 180°C, and an air outlet temperature of 82°C to obtain essential oil microcapsules.

[0048] The essential oil is prepared by mixing cumin essential oil, oregano essential oil and white mustard volatile oil in a mass ratio of 2:1:1.

[0049] The preparation method of mango kernel starch comprises the following steps:

[0050] The mango core is washed, dried and crushed to obtain mango core powder, and then the mango core powder is mixed with a sodium pyrosulfite aqueous solution with a concentration of 0.16wt% in a mass ratio of 1:8, and soaked for 18 hours to obtain a slurry; the obtained slurry is passed through a 100-mesh sieve, then through a 300-mesh sieve, and then settled, the supernatant is decanted, the starch layer is resuspended in water, and then centrifuged at 8000rpm for 5min, the upper non-white layer is discarded, and the lower starch layer is resuspended in water, and then centrifuged again at 8000rpm for 5min, the supernatant is discarded, and the white starch precipitate is collected; the obtained starch precipitate is dried in a hot air oven at 45°C, and then crushed and passed through a 100-mesh sieve to obtain mango core starch.

[0051] Example 3

[0052] A method for preparing a preservative having the function of extending the shelf life of fruits and vegetables, which is different from Example 1 in that the method for preparing the essential oil microcapsules comprises the following steps:

[0053] 15 parts by weight of modified mango kernel starch are added to 35 parts by weight of water, and then mixed and stirred at 50°C and 12000 rpm for 15 minutes to obtain a capsule wall material dispersion 1; 6 parts by weight of essential oil are added to the above-mentioned capsule wall material dispersion 1, and then stirred and emulsified at 18000 rpm for 25 minutes to obtain emulsion a; 15 parts by weight of maltodextrin are added to 50 parts by weight of water, and then mixed and stirred at 50°C and 900 rpm for 8 minutes to obtain a capsule wall material dispersion 2; emulsion a is added to the above-mentioned capsule wall material dispersion 2, and then stirred and mixed at 15000 rpm for 8 minutes to obtain emulsion b; emulsion b is subjected to high-pressure homogenization 3 times under the condition of a homogenization pressure of 38 MPa to form a fine and uniform emulsion, and then spray-dried under the conditions of an atomization pressure of 1.2 MPa, an air inlet temperature of 180°C, and an air outlet temperature of 82°C to obtain essential oil microcapsules.

[0054] The essential oil is prepared by mixing cumin essential oil, oregano essential oil and white mustard volatile oil in a mass ratio of 2:1:1.

[0055] The preparation method of the modified mango kernel starch comprises the following steps:

[0056] The mango kernel is washed, dried, and crushed to obtain mango kernel powder, and then the mango kernel powder is mixed with a sodium metabisulfite aqueous solution with a concentration of 0.16wt% in a mass ratio of 1:8, and soaked for 18 hours to obtain a slurry; the obtained slurry is passed through a 100-mesh sieve, and then through a 300-mesh sieve, and then settled, the supernatant is decanted, the starch layer is resuspended in water, and then centrifuged at 8000rpm for 5min, the upper non-white layer is discarded and the lower starch layer is resuspended in water, and then centrifuged again at 8000rpm for 5min, the supernatant is discarded, and the white starch precipitate is collected; the obtained starch precipitate is dried in a hot air oven at 45°C, and then crushed The method comprises the steps of: passing the mixture through a 100-mesh sieve to obtain mango kernel starch; mixing the mango kernel starch with water in a mass ratio of 1:7 to form a suspension, and dropping a 1.5 wt% hydrogen peroxide aqueous solution into the suspension under continuous stirring at 500 rpm, and reacting the mixture at 30°C for 2.5 hours, wherein the mass ratio of the hydrogen peroxide aqueous solution to the starch is 5:100; then adding a 1 mol / L sodium hydroxide aqueous solution to adjust the pH to 8, filtering, collecting the starch precipitate, washing the mixture with water 4 times the total mass of the starch precipitate for 5 times, and finally washing the mixture with a 95 wt% ethanol aqueous solution 4 times the total mass of the starch precipitate for 2 times, and drying the mixture at 45°C for 24 hours to obtain the modified mango kernel starch.

[0057] Example 4

[0058] A method for preparing a preservative having the function of extending the shelf life of fruits and vegetables, which is different from Example 1 in that the method for preparing the essential oil microcapsules comprises the following steps:

[0059] 15 parts by weight of a carrier are added to 35 parts by weight of water, and then the mixture is stirred at 50°C and 12000 rpm for 15 minutes to obtain a capsule wall material dispersion 1; 6 parts by weight of essential oil are added to the above-mentioned capsule wall material dispersion 1, and then the mixture is stirred and emulsified at 18000 rpm for 25 minutes to obtain an emulsion a; 15 parts by weight of maltodextrin are added to 50 parts by weight of water, and then the mixture is stirred at 50°C and 900 rpm for 8 minutes to obtain a capsule wall material dispersion 2; emulsion a is added to the above-mentioned capsule wall material dispersion 2, and then the mixture is stirred and mixed at 15000 rpm for 8 minutes to obtain an emulsion b; emulsion b is subjected to high-pressure homogenization 3 times under a homogenization pressure of 38 MPa to form a fine and uniform emulsion, and then the emulsion is spray-dried under an atomization pressure of 1.2 MPa, an air inlet temperature of 180°C, and an air outlet temperature of 82°C to obtain essential oil microcapsules.

[0060] The essential oil is prepared by mixing cumin essential oil, oregano essential oil and white mustard volatile oil in a mass ratio of 2:1:1.

[0061] The carrier is a mixture of mango kernel starch and angustifolia gum in a mass ratio of 1:2.

[0062] The preparation method of the mango kernel starch is consistent with that in Example 2.

[0063] Example 5

[0064] A method for preparing a preservative having the function of extending the shelf life of fruits and vegetables, which is different from Example 1 in that the method for preparing the essential oil microcapsules comprises the following steps:

[0065] 15 parts by weight of a carrier are added to 35 parts by weight of water, and then the mixture is stirred at 50°C and 12000 rpm for 15 minutes to obtain a capsule wall material dispersion 1; 6 parts by weight of essential oil are added to the above-mentioned capsule wall material dispersion 1, and then the mixture is stirred and emulsified at 18000 rpm for 25 minutes to obtain an emulsion a; 15 parts by weight of maltodextrin are added to 50 parts by weight of water, and then the mixture is stirred at 50°C and 900 rpm for 8 minutes to obtain a capsule wall material dispersion 2; emulsion a is added to the above-mentioned capsule wall material dispersion 2, and then the mixture is stirred and mixed at 15000 rpm for 8 minutes to obtain an emulsion b; emulsion b is subjected to high-pressure homogenization 3 times under a homogenization pressure of 38 MPa to form a fine and uniform emulsion, and then the emulsion is spray-dried under an atomization pressure of 1.2 MPa, an air inlet temperature of 180°C, and an air outlet temperature of 82°C to obtain essential oil microcapsules.

[0066] The essential oil is prepared by mixing cumin essential oil, oregano essential oil and white mustard volatile oil in a mass ratio of 2:1:1.

[0067] The carrier is a mixture of modified mango kernel starch and angustifolia gum in a mass ratio of 1:2.

[0068] The preparation method of the modified mango kernel starch is consistent with that of Example 3.

[0069] Comparative Example 1

[0070] A method for preparing a preservative capable of extending the shelf life of fruits and vegetables comprises the following steps:

[0071] 4% essential oil, 0.3% 1-methylcyclopropene, 1.5% sodium alginate, 0.03% citric acid, 0.3% calcium chloride, 0.3% glycerol, 0.03% Tween-80 and the balance water are mixed uniformly to obtain a preservative.

[0072] The essential oil is prepared by mixing cumin essential oil, oregano essential oil and white mustard volatile oil in a mass ratio of 2:1:1.

[0073] Comparative Example 2

[0074] A method for preparing a preservative capable of extending the shelf life of fruits and vegetables comprises the following steps:

[0075] 1.5% sodium alginate, 0.3% 1-methylcyclopropene, 0.03% citric acid, 0.3% calcium chloride, 0.3% glycerol, 0.03% Tween-80 and the balance water are mixed uniformly to obtain a preservative.

[0076] Test Example 1

[0077] Select blueberry fruits of uniform size, free of mechanical damage, and free of pests and diseases from the same batch of harvest as the fruits to be preserved. Soak the selected blueberries in the preservative solution prepared by Examples 1-5 and Comparative Examples 1-2 of the present invention for preservation treatment for 5 minutes, then take them out, dry them at room temperature, put them into PE boxes (80 per box), and wrap them with PE preservative film as the experimental group; in addition, blueberries that have not been preserved are used as the control group; the number of experimental groups in each experimental group and the control group is 10 boxes. Store each group of blueberry fruits at a humidity of 50% and room temperature, and test them once after 3 days, 7 days, and 14 days of storage, respectively. Test and record the number of rotten fruits and the fruit loss rate of each group of blueberries during storage, and calculate the rot rate and fruit loss rate. Among them, blueberry fruits are considered rotten when they become moldy, the texture of the flesh collapses, and the color of the flesh changes from white to brown; the rotten fruits are picked out and accumulated for the next statistics. The calculation formula for the rot rate and loss rate of the fruit is as follows:

[0078] Rot rate (%) = number of rotten fruits / total number of fruits × 100%;

[0079] Loss rate (%) = (total mass of fruit before storage - total mass of fruit after storage) / total mass of fruit before storage × 100%;

[0080] The specific test results are shown in Table 1.

[0081] Table 1

[0082]

[0083] As shown in Table 1, compared with the control group, the fresh-keeping effects of Examples 1-5 and Comparative Examples 1-2 are obvious, and the fruit rot rate and loss rate are significantly reduced, indicating that the fresh-keeping agent prepared by the present invention can prolong the shelf life of fruits and vegetables; by comparing Examples 1-5 and Comparative Examples 1-2, it is found that the fruit rot rate and loss rate of Examples 1-5 are significantly lower than those of Comparative Examples 1-2; by comparing Examples 1-5, it is found that the fruit rot rate and loss rate of Examples 4-5 are significantly lower than those of Examples 1-3, among which the fruit rot rate and loss rate of Example 5 are the lowest, and the rot rate of the fruit after storage at room temperature for 14 days is only 15.26%, and the loss rate is only 9.80%. The reason may be that the cumin essential oil, oregano essential oil and white mustard volatile oil introduced in the essential oil microcapsules contain a variety of compounds with antibacterial and antifungal activity. These ingredients can inhibit or kill microorganisms that cause blueberry decay, and can effectively reduce the decay rate of blueberries by reducing the growth of pathogens. In addition, the antioxidant components in the essential oils can neutralize free radicals, reduce oxidative stress, and protect blueberry cells from oxidative damage. This protective effect delays cell aging and deterioration, thereby reducing quality loss. At the same time, the essential oil microcapsules may reduce the metabolic rate of blueberries by affecting their respiration, slowing down the ripening and aging process. For example, the ingredients in the essential oils can inhibit the production of ethylene and reduce the respiration rate of blueberries, thereby delaying their ripening and decay. In addition, as wall materials, galangal gum and modified mango kernel starch can form a protective film on the surface of blueberries, which can reduce water evaporation and the invasion of external microorganisms, maintain the freshness and hardness of blueberries, and reduce weight loss. In addition, the wall material can control the release rate of the essential oil, so that the essential oil is released slowly during storage, extending the shelf life of the essential oil and improving the preservation effect.

[0084] By comparing Example 4 in which galangal gum and mango kernel starch were selected as wall materials for preparing essential oil microcapsules, it was found that Example 5 in which galangal gum and modified mango kernel starch were selected as wall materials for preparing essential oil microcapsules could more effectively reduce the mass loss rate and decay rate of blueberries during storage at room temperature. The reason for this may be that compared with mango kernel starch, oxidative modification can improve the mechanical properties of mango kernel starch, such as tensile strength and ductility. This enhanced mechanical property helps to form a tougher and more stable microcapsule wall, thereby better protecting the essential oil during storage and handling, reducing the rupture of the microcapsules, and ensuring the continuous release and effectiveness of the essential oil. In addition, oxidized mango kernel starch may have better barrier properties due to the change in its chemical structure, especially the barrier to water vapor and oxygen, which helps to reduce the water loss and oxidation reaction of blueberries, thereby reducing mass loss and decay rate.

[0085] Test Example 2

[0086] Select the screw peppers of the same batch of harvested ones with uniform length, no mechanical damage, and no diseases and insect pests as the vegetables to be preserved. Soak the selected screw peppers in the preservative solution prepared by Examples 1-5 of the present invention and Comparative Examples 1-2 for preservation treatment for 8 minutes, then take them out, dry them at room temperature, and pack them into boxes (500 per box) as the experimental group; in addition, the screw peppers that have not been preserved are used as the control group; the number of experimental groups in each experimental group and the control group is 10 boxes. Store each group of screw peppers at a humidity of 50% and 8°C, and test them once after 7 days, 14 days, 21 days, and 28 days of storage, test and record the wilting of the screw pepper fruits in each group during the storage period, and calculate the wilting rate. Among them, the wilting is considered to be obvious volume shrinkage of the screw pepper fruit, wrinkles on the epidermis, softening of the fruit texture, and loosening of the connection between the fruit and the fruit stalk; the wilted fruits are counted and put back into the corresponding treatment box. The calculation formula of the wilting rate of the fruit is as follows:

[0087] Wilting rate (%) = number of wilting fruits / total number of fruits × 100%;

[0088] The specific test results are shown in Table 2.

[0089] Table 2

[0090]

[0091] As can be seen from Table 2, compared with the control group, the wilting rate of the screw pepper fruits in Examples 1-5 and Comparative Examples 1-2 is significantly reduced, indicating that the preservative prepared by the present invention can maintain the hardness of fruits and vegetables, prevent fruits and vegetables from softening and deforming, and extend the shelf life of fruits and vegetables. Comparing Examples 1-5 and Comparative Examples 1-2, it is found that the fruit wilting rate of Example 1-5 is significantly lower than that of Comparative Example 1-2; Comparing Examples 1-5, it is found that the fruit wilting rate of Examples 4-5 is significantly lower than that of Example 1-3, among which Example 5 has the lowest fruit wilting rate, and the rot rate of screw pepper fruits after 28 days of storage is only 1.57%. The reason for the analysis may be that the introduction of essential oil microcapsules is conducive to the long-term preservation of fruits and vegetables. Essential oil microcapsules can cooperate with other raw material components to form a protective film on the surface of screw pepper fruits. This film can reduce water evaporation and the invasion of external microorganisms, maintain the freshness and hardness of the fruit, and reduce the wilting rate of the fruit. In addition, during the preservation process, the essential oil microcapsules can control the release rate of the essential oils, so that the essential oils are slowly released during storage, achieving a long-term preservation effect. The active ingredients contained in the essential oil microcapsules, such as cumin essential oil, oregano essential oil, and white mustard volatile oil, have antibacterial and antioxidant properties, which can inhibit the growth of microorganisms, reduce oxidative damage, and delay the aging of fruits and vegetables; and may also affect the metabolism of the cell walls of fruits and vegetables, by inhibiting the activity of cell wall degrading enzymes, maintaining the integrity of the cell walls, thereby maintaining the hardness of fruits and vegetables, preventing fruits and vegetables from softening and deforming, and at the same time regulating the respiration of fruits and vegetables, by reducing the respiration intensity, thereby reducing the material consumption inside fruits and vegetables and extending the shelf life of fruits and vegetables.

Claims

1. A preservative having the function of extending the shelf life of fruits and vegetables, characterized in that: Calculated by weight percentage, the invention comprises 3-5% essential oil microcapsules, 0.1-0.5% 1-methylcyclopropene, 0.5-1.5% sodium alginate, 0.01-0.05% citric acid, 0.1-0.5% calcium chloride, 0.1-0.4% glycerol, 0.01-0.05% Tween-80, and the balance is water.

2. The preservative having the function of extending the shelf life of fruits and vegetables as claimed in claim 1, characterized in that: The 1-methylcyclopropene is in the form of microcapsule granules, wherein the content of 1-methylcyclopropene is 1-5%.

3. The preservative having the function of extending the shelf life of fruits and vegetables as claimed in claim 1, characterized in that: The preparation method of the essential oil microcapsules comprises the following steps, measured by weight: 10-20 parts of the carrier are added to 20-40 parts of water, and then mixed and stirred at 40-60°C and 10000-13000 rpm for 10-20 minutes to obtain a capsule wall material dispersion 1; 3-8 parts of essential oil are added to the capsule wall material dispersion 1, and then stirred and emulsified at 15000-20000 rpm for 20-30 minutes to obtain an emulsion a; 10-20 parts of maltodextrin are added to 30-70 parts of water, and then mixed and stirred at 50-60°C and 800-1000 rpm; The mixture was stirred for 5-10 minutes to obtain a capsule wall material dispersion 2; emulsion a was added to the capsule wall material dispersion 2, and then stirred and mixed at 12000-18000 rpm for 5-10 minutes to obtain emulsion b; emulsion b was subjected to high-pressure homogenization for 2-3 times at a homogenization pressure of 35-40 MPa to form a fine and uniform emulsion, and then spray-dried at an atomization pressure of 1-1.5 MPa, an inlet air temperature of 160-190° C., and an outlet air temperature of 75-85° C. to obtain essential oil microcapsules.

4. The preservative having the function of extending the shelf life of fruits and vegetables as claimed in claim 1, characterized in that: The essential oil is selected from one or more combinations of cumin essential oil, oregano essential oil and white mustard volatile oil; the essential oil is prepared by mixing cumin essential oil, oregano essential oil and white mustard volatile oil in a mass ratio of 1-2:1-2:1-2.

5. The preservative having the function of extending the shelf life of fruits and vegetables as claimed in claim 3, characterized in that: The carrier is selected from one or a combination of plant starch and angustifolia gum; the carrier is a mixture of plant starch and angustifolia gum in a mass ratio of 1:1-3.

6. The preservative having the function of extending the shelf life of fruits and vegetables as claimed in claim 5, characterized in that: The plant starch is selected from at least one of mango kernel starch and modified mango kernel starch.

7. The preservative having the function of extending the shelf life of fruits and vegetables as claimed in claim 6, characterized in that: The preparation method of mango kernel starch comprises the following steps: The mango kernel is washed, dried and crushed to obtain mango kernel powder, and then the mango kernel powder is mixed with a sodium pyrosulfite aqueous solution with a concentration of 0.15-0.2wt% in a mass ratio of 1:2-10, and soaked for 12-24 hours to obtain a slurry; the obtained slurry is passed through a 100-200 mesh sieve, and then through a 200-300 mesh sieve, and then settled, the supernatant is decanted, the starch layer is resuspended in water, and then centrifuged at 7000-9000rpm for 4-8min, the upper non-white layer is discarded, the lower starch layer is resuspended in water, and then centrifuged again at 7000-9000rpm for 5-8min, the supernatant is discarded, and a white starch precipitate is collected; the obtained starch precipitate is dried in a hot air oven at 40-50℃, and then crushed and passed through a 100-200 mesh sieve to obtain mango kernel starch.

8. The preservative having the function of extending the shelf life of fruits and vegetables as claimed in claim 6, characterized in that: The preparation method of the modified mango kernel starch comprises the following steps: The mango kernel is washed, dried and crushed to obtain mango kernel powder, and then the mango kernel powder is mixed with a sodium metabisulfite aqueous solution with a concentration of 0.15-0.2wt% in a mass ratio of 1:2-10, and soaked for 12-24 hours to obtain a slurry; the obtained slurry is passed through a 100-200 mesh sieve, and then through a 200-300 mesh sieve, and then settled, the supernatant is decanted, the starch layer is resuspended in water, and then centrifuged at 7000-9000rpm for 4-8min, the upper non-white layer is discarded, and the lower starch layer is resuspended in water, and then centrifuged again at 7000-9000rpm for 5-8min, the supernatant is discarded, and the white starch precipitate is collected; the obtained starch precipitate is dried in a hot air oven at 40-50℃, and then crushed for 1 The invention relates to a method for preparing mango kernel starch by sieve through a 00-200 mesh sieve to obtain mango kernel starch; mixing the mango kernel starch with water in a mass ratio of 1:5-8 to form a suspension, and dripping a 1-2wt% hydrogen peroxide aqueous solution into the suspension under continuous stirring at 400-600rpm, and reacting at 28-35°C for 1-3h, wherein the mass ratio of the hydrogen peroxide aqueous solution to the starch is 3-7:100; then adding a 0.5-1mol / L sodium hydroxide aqueous solution to adjust the pH to 7-8, filtering, collecting starch precipitates, washing 3-4 times with water 3-5 times the total mass of the starch precipitates, and finally washing 1-2 times with a 90-95wt% ethanol aqueous solution 3-5 times the total mass of the starch precipitates, and drying at 40-50°C for 22-25h to obtain modified mango kernel starch.

9. The method for preparing the preservative having the function of extending the shelf life of fruits and vegetables according to any one of claims 1 to 8, characterized in that: The following steps are involved: According to weight percentage, 3-5% essential oil microcapsules, 0.5-1.5% sodium alginate, 0.01-0.05% citric acid, 0.1-0.5% calcium chloride, 0.1-0.4% glycerol, 0.01-0.05% Tween-80, 0.1-0.5% 1-methylcyclopropene and the balance water are mixed evenly to obtain a preservative.

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