Dynamic atmosphere combined with intermittent 1-mcp fumigation storage preservation method

Abstract

The application provides a storage and preservation method of dynamic air conditioning combined with intermittent 1-MCP fumigation, which divides the storage period into three stages of early stage, middle stage and late stage according to the physiological state of autumn month pears after harvesting, and adjusts the air conditioning parameters correspondingly. The high-oxygen environment in the early stage ensures normal respiratory metabolism of the fruit and avoids the generation of peculiar smell by anaerobic respiration. The oxygen is gradually reduced and the carbon is gradually increased in the middle stage to realize smooth transition and reduce physiological stress damage. The low-oxygen and high-carbon dioxide environment in the late stage maximally inhibits respiratory consumption and delays the loss of nutrients. Meanwhile, the intermittent scheme of first fumigation in the warehouse combined with supplementary fumigation every 25-35 days is adopted to maintain the effective concentration of 1-methylcyclopropene and continuously block the ethylene receptor. After the cooperation of the two, the ethylene inhibition effect can be maintained throughout the whole process. The fruit flesh crispness can be maintained above 85% of the initial value after 150 days of storage, and there is no obvious peculiar smell and peel browning. Compared with the existing constant air conditioning scheme, the effective storage period is prolonged by more than 30 days.

Description

Technical Field

[0001] This invention relates to the field of modified atmosphere storage technology for fruits, and in particular to a method for storage and preservation of fruits using dynamic modified atmosphere combined with intermittent 1-MCP fumigation. Background Technology

[0002] The Akizuki pear has a yellowish-brown peel, making it extremely attractive. Its flesh is milky white, with a small core and an edible rate of over 95%. The flesh is fine-textured, crisp, juicy, and sweet, exhibiting good storage properties. However, as a climacteric fruit, the Akizuki pear is prone to softening and spoilage at higher temperatures after harvesting. This results in rapid softening, peel cracking, browning of the flesh, and a short shelf life, severely limiting its commercial value for off-season sales. Existing technologies include methods for preserving Akizuki pears using a low-temperature environment combined with controlled atmosphere and 1-methylcyclopropene. This method first soaks the Akizuki pears in a solution containing preservatives to improve preservation. Then, it is stored at low temperatures in the presence of controlled atmosphere and 1-methylcyclopropene, adjusting the controlled atmosphere to the optimal oxygen / carbon dioxide concentration. Combined with 1-methylcyclopropene, this further reduces ethylene production and the rate of decay. Related studies have shown that Akizuki pears are relatively tolerant of carbon dioxide. Controlled atmosphere storage with 5% oxygen and 3% carbon dioxide or 5% oxygen and 1% carbon dioxide can inhibit fruit softening and maintain good quality of Akizuki pears during refrigeration and shelf life.

[0003] However, the existing technologies still have the following shortcomings. First, the current technologies use constant gas parameters for storage, which cannot match the physiological characteristics of Akizuki pears at different stages after harvest. In the early post-harvest period, the fruit's respiration intensity is high, and ethylene release gradually increases. If it is directly introduced into a low-oxygen environment at this time, it is easy to induce anaerobic respiration, resulting in the accumulation of metabolites such as ethanol and acetaldehyde, which produces an irritating odor in the pulp and destroys the original flavor of the fruit. Second, the 1-methylcyclopropene introduced in the current technology will gradually degrade with the micro-aeration of the storage chamber and adsorption by the fruit tissue. Usually, the effective concentration drops below the threshold after 60 days of storage, which cannot continuously block ethylene receptors, leading to a gradual increase in ethylene release from the fruit, accelerated degradation of the pulp cell wall, and a significant decrease in firmness. Third, a long-term constant carbon dioxide concentration can easily cause chronic physiological damage to the peel cells, inducing chilling injury symptoms such as peel blackening and pulp browning, which is particularly prominent in the later stages of storage when the fruit's resistance decreases. In addition, when the oxygen and carbon dioxide concentration ratio is 5% to 5% or 3% to 3%, the fruit's respiration intensity increases abnormally, the fruit produces an odor, and loses its edible value.

[0004] Therefore, there is an urgent need in this field for a storage and preservation method that can dynamically adjust the modified atmosphere parameters according to the postharvest physiological rhythm of Akizuki pears and continuously maintain the effective concentration of 1-methylcyclopropene, in order to solve the technical problem that the preservation effect of existing constant modified atmosphere and one-time fumigation schemes decreases significantly in the later stages of storage. Summary of the Invention

[0005] The purpose of this invention is to provide a storage and preservation method that combines dynamic modified atmosphere storage with intermittent 1-MCP fumigation, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a storage and preservation method combining dynamic modified atmosphere packaging with intermittent 1-MCP fumigation, comprising the following steps: After harvesting, keep the stem and stalk of the Akizuki pear and soak it in a preservative solution for 5-10 minutes in the dark. Then take it out and let it dry. Place the soaked Akizuki pear in a low temperature environment of 4-10℃ and relative humidity of 85-90% and store it under artificial atmosphere conditions. The controlled atmosphere storage is divided into three stages according to the storage period, and the gas parameters are dynamically adjusted in each stage as follows: the first 30 days of storage is the early stage, maintaining an oxygen concentration of 5%–8%, a carbon dioxide concentration of 1%–2%, and nitrogen as the balance gas; the 31st–90th days of storage is the middle stage, adjusting to an oxygen concentration of 2%–4%, a carbon dioxide concentration of 2%–4%, and nitrogen as the balance gas; the 91st day of storage to the end of storage is the late stage, adjusting to an oxygen concentration of 1%–2.5%, a carbon dioxide concentration of 3%–5%, and nitrogen as the balance gas. During storage, the first 1-methylcyclopropene fumigation is carried out upon entry into the warehouse, and thereafter fumigation is carried out every 25 to 35 days. The concentration of 1-methylcyclopropene in each fumigation is 0.5 to 2 μL / L, and the fumigation time is 12 to 24 hours.

[0007] Preferably, the preservative solution contains the following concentrations of raw materials: melatonin 0.5–2 mmol / L, citric acid 0.05–0.2 g / L, ferrous sulfate 0.02–0.3 g / L, calcium chloride 0.5–2 g / L, surfactant 0.1–0.5 g / L, with the balance being water.

[0008] Preferably, the surfactant is either laurate or monooleate.

[0009] Preferably, the first 1-methylcyclopropene fumigation is completed within 24 hours after the warehouse is opened, and each subsequent supplementary fumigation is completed within 48 hours before or after the corresponding time point.

[0010] Preferably, the switching of gas parameters at each stage is done gradually, and is completed step by step over 3 to 5 days.

[0011] Preferably, the low-temperature environment is 5-7°C and the relative humidity is 85-90%.

[0012] Preferably, the initial oxygen concentration is 6% to 7% and the carbon dioxide concentration is 1% to 1.5%.

[0013] Preferably, the intermediate oxygen concentration is 3% to 4% and the carbon dioxide concentration is 2.5% to 3%.

[0014] Preferably, the oxygen concentration in the later stage is 1% to 2% and the carbon dioxide concentration is 4% to 5%.

[0015] Preferably, the fumigation is performed every 25 to 35 days instead of every 30 days.

[0016] The present invention achieves the following beneficial technical effects compared to the prior art: This invention provides a storage and preservation method combining dynamic modified atmosphere (MAP) with intermittent 1-MCP fumigation. The storage period is divided into three stages—early, middle, and late—based on the post-harvest physiological state of the Akizuki pear, with corresponding adjustments to the MAP parameters. The early stage uses a high-oxygen environment to ensure normal fruit respiration and metabolism, avoiding anaerobic respiration and off-flavors. The middle stage gradually decreases oxygen and increases carbon dioxide levels for a smooth transition, reducing physiological stress damage. The late stage uses a low-oxygen, high-carbon dioxide environment to maximize the inhibition of respiration and delay nutrient loss. Simultaneously, an intermittent fumigation scheme, combining initial fumigation upon arrival with fumigation every 25-35 days, maintains the effective concentration of 1-methylcyclopropene throughout the process, continuously blocking ethylene receptors. This combination maintains the ethylene inhibition effect throughout the entire storage period. Even after 150 days of storage, the fruit maintains more than 85% of its initial crispness, with no obvious off-flavors or browning of the peel. This extends the effective storage period by more than 30 days compared to existing constant MAP schemes, effectively solving the technical problems of existing constant MAP methods failing to match the physiological needs of different fruit stages and the limited effective period of a single 1-methylcyclopropene fumigation. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] The purpose of this invention is to provide a storage and preservation method that combines dynamic modified atmosphere storage with intermittent 1-MCP fumigation, in order to solve the problems existing in the prior art.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to specific embodiments.

[0020] Example 1 A method for storing and preserving Akizuki pears using dynamic modified atmosphere packaging combined with intermittent 1-MCP fumigation, comprising the following steps: Prepare a preservative solution containing 1 mmol / L melatonin, 0.1 g / L citric acid, 0.2 g / L ferrous sulfate, 1 g / L calcium chloride, and 0.2 g / L monooleate, with the remainder being water. After harvesting, retain the stem and stalk of the Akizuki pear and immerse it in the preservative solution for 10 minutes in the dark, then remove and air dry. Store the soaked Akizuki pears in a low-temperature environment of 5–7°C and 85–90% relative humidity under dynamic controlled atmosphere conditions. The first 30 days of storage constitute the initial storage period. The oxygen concentration is 6% and the carbon dioxide concentration is 1.5%. During the 31st to 90th day of storage, the concentration is adjusted to 3% and 3% respectively. From the 91st day of storage to the end of storage, the concentration is adjusted to 2% and 4% respectively. The first 1-methylcyclopropene fumigation is carried out within 24 hours after entering the warehouse, with a concentration of 1 μL / L and a fumigation time of 12 hours. Thereafter, fumigation is carried out once every 30 days, with a concentration of 1 μL / L and a fumigation time of 12 hours, until the end of storage.

[0021] Example 2 A method for storing and preserving Akizuki pears using dynamic modified atmosphere packaging combined with intermittent 1-MCP fumigation, comprising the following steps: Prepare a preservative solution containing 1 mmol / L melatonin, 0.1 g / L citric acid, 0.1 g / L ferrous sulfate, 0.8 g / L calcium chloride, and 0.3 g / L laurate, with the remainder being water. After harvesting, retain the stem and stalk of the Akizuki pear and immerse it in the preservative solution for 8 minutes in the dark, then remove and air dry. Store the soaked Akizuki pears in a low-temperature environment of 5–7°C and 85–90% relative humidity under dynamic controlled atmosphere conditions. The first 30 days of storage are the initial stage, maintaining a high oxygen concentration. The initial concentration of oxygen was 7% and carbon dioxide was 1%. During the middle period of storage (days 31-90), the concentration was adjusted to 4% and 2.5%. During the later period of storage (day 91 to the end of storage), the concentration was adjusted to 1.5% and 4.5%. The first 1-methylcyclopropene fumigation was carried out within 24 hours of entering the warehouse at a concentration of 0.8 μL / L for 16 hours. Thereafter, fumigation was carried out every 28 days at a concentration of 0.8 μL / L for 16 hours until the end of storage.

[0022] Example 3 A method for storing and preserving Akizuki pears using dynamic modified atmosphere packaging combined with intermittent 1-MCP fumigation, comprising the following steps: Prepare a preservative solution containing 0.5 mmol / L melatonin, 0.2 g / L citric acid, 0.2 g / L ferrous sulfate, 1 g / L calcium chloride, and 0.2 g / L monooleate, with the remainder being water. After harvesting, retain the stem and stalk of the Akizuki pear and immerse it in the preservative solution for 10 minutes in the dark, then remove and air dry. Store the soaked Akizuki pears in a low-temperature environment of 5–7°C and 85–90% relative humidity under dynamic controlled atmosphere conditions. The first 30 days of storage are considered the initial stage, maintaining oxygen levels. The initial concentration of oxygen was 5% and the concentration of carbon dioxide was 2%. During the middle period of storage (days 31-90), the concentration was adjusted to 2% and 3.5%. During the later period of storage (day 91 to the end of storage), the concentration was adjusted to 1% and 5%. The first 1-methylcyclopropene fumigation was carried out within 24 hours of entering the warehouse, with a concentration of 1.5 μL / L and a fumigation time of 24 hours. Thereafter, fumigation was carried out every 35 days, with a concentration of 1.5 μL / L and a fumigation time of 24 hours, until the end of storage.

[0023] Comparative Example 1 A method for preserving and keeping Akizuki pears, the steps are as follows: Prepare a preservative solution containing 1 mmol / L melatonin, 0.1 g / L citric acid, 0.2 g / L ferrous sulfate, 1 g / L calcium chloride, 0.2 g / L monooleate, and the remainder water. After harvesting, keep the stem and stalk of the Akizuki pear and soak it in the preservative solution for 10 minutes in the dark, then remove and air dry. Store the soaked Akizuki pears in a low-temperature environment of 5–7℃ and relative humidity of 85–90% under constant artificial controlled atmosphere conditions: 91% nitrogen, 8% oxygen, and 1% carbon dioxide. Fumigate with 1-methylcyclopropene within 24 hours of storage at a concentration of 1 μL / L; no further fumigation is required thereafter.

[0024] Comparative Example 2 A method for preserving and keeping Akizuki pears, the steps are as follows: Prepare a preservative solution containing 1 mmol / L melatonin, 0.1 g / L citric acid, 0.2 g / L ferrous sulfate, 1 g / L calcium chloride, 0.2 g / L monooleate, and the remainder water. After harvesting, keep the stem and stalk of the Akizuki pear and soak it in the preservative solution for 10 minutes in the dark, then remove and air dry. Store the soaked Akizuki pears in a low-temperature environment of 5–7℃ and relative humidity of 85–90% under constant artificial controlled atmosphere conditions: 92% nitrogen, 5% oxygen, and 3% carbon dioxide. Fumigate with 1-methylcyclopropene within 24 hours of storage at a concentration of 1 μL / L; no further fumigation is required thereafter.

[0025] Comparative Example 3 A method for preserving and keeping Akizuki pears, the steps are as follows: Prepare a preservative solution containing 1 mmol / L melatonin, 0.1 g / L citric acid, 0.2 g / L ferrous sulfate, 1 g / L calcium chloride, and 0.2 g / L monooleate, with the remainder being water. After harvesting, keep the stem and stalk of the Akizuki pear and soak it in the preservative solution for 10 minutes in the dark, then remove and air dry. Store the soaked Akizuki pears in a low-temperature environment of 5–7℃ and relative humidity of 85–90% under dynamic controlled atmosphere conditions: Days 1–30 of storage (early stage) maintain an oxygen concentration of 6% and a carbon dioxide concentration of 1.5%; days 31–90 (middle stage) adjust the oxygen and carbon dioxide concentrations to 3%; and days 91 to the end of storage (late stage) adjust the oxygen and carbon dioxide concentrations to 2% and 4%. However, do not perform 1-methylcyclopropene fumigation after storage.

[0026] Comparative Example 4 A method for preserving and keeping Akizuki pears, the steps are as follows: Prepare a preservative solution containing 1 mmol / L melatonin, 0.1 g / L citric acid, 0.2 g / L ferrous sulfate, 1 g / L calcium chloride, 0.2 g / L monooleate, and the remainder water. After harvesting, keep the stem and stalk of the Akizuki pear and soak it in the preservative solution for 10 minutes in the dark, then remove and air dry. Store the soaked Akizuki pears in a low-temperature environment of 5–7℃ and relative humidity of 85–90% under constant controlled atmosphere conditions: 91% nitrogen, 8% oxygen, and 1% carbon dioxide. Within 24 hours of storage, perform the first 1-methylcyclopropene fumigation at a concentration of 1 μL / L for 12 hours. Thereafter, perform supplementary fumigation every 30 days at a concentration of 1 μL / L for 12 hours.

[0027] Comparative Example 5 Akizuki pears that have not undergone any treatment were used as comparative example 5.

[0028] The storage quality test results of Akizuki pears in Examples 1-3 and Comparative Examples 1-5 of the present invention are shown in Table 1.

[0029] Table 1. Effects of different storage methods on the quality of Akizuki pears

[0030] Note: Crispness retention rate is calculated based on fruit crispness of 100% at the time of storage; browning index 0 indicates no browning, 1 indicates complete browning; "—" indicates that the comparison ratio could not continue to be effectively stored after 120 days, and data for 150 days were not measured.

[0031] Table 1 shows that Comparative Example 1, using a constant modified atmosphere combined with a single 1-methylcyclopropene fumigation, had a water loss rate of 3.42% and a fruit crispness retention rate of 78.6% after 120 days of storage. Although this delayed the deterioration of fruit quality to some extent, the quality declined significantly after 120 days, making further effective storage impossible. Comparative Example 2, using different constant modified atmosphere parameters, yielded similar results to Comparative Example 1, with a water loss rate of 3.49% and a crispness retention rate of 76.3% after 120 days of storage. Comparative Example 3, using dynamic modified atmosphere but without 1-methylcyclopropene fumigation, experienced a water loss rate of 5.12% and a rot rate of 2.13% after 120 days of storage. The fruit crispness retention rate was only 65.2%, accompanied by a slight off-odor. This indicates that 1-methylcyclopropene plays an irreplaceable role in delaying the deterioration of Akizuki pear quality. Comparative Example 4, using a constant controlled atmosphere combined with intermittent 1-methylcyclopropene supplementary fumigation, showed a water loss rate of 3.38% and a crispness retention rate of 80.1% after 120 days of storage, which was superior to the single fumigation scheme of Comparative Example 1. This indicates that intermittent supplementary fumigation is beneficial for maintaining the preservation effect in the later stages of storage. However, due to the constant controlled atmosphere parameters, it cannot match the physiological needs of the fruit at different stages, and its crispness retention rate after 120 days of storage is still significantly lower than that of the embodiments of the present invention. Comparative Example 5, without any treatment, showed a water loss rate of 12.45% and a rot rate as high as 30.21% after 120 days of storage, with a crispness retention rate of only 41.5%, indicating that Akizuki pears are difficult to store for a long time without any preservation treatment.

[0032] Examples 1-3 of this invention employ a dynamic controlled atmosphere combined with intermittent 1-methylcyclopropene supplementary fumigation scheme. After 120 days of storage, the water loss rate was below 2.8%, the fruit crispness retention rate was above 87%, and no rot or off-odor occurred. After 150 days of storage, the water loss rate of Examples 1-3 was controlled below 4.1%, the rot rate was below 0.3%, the fruit crispness retention rate was above 83%, and no off-odors such as ethanol were produced, with only slight browning of the peel. These results demonstrate that this invention, by dividing the storage period into three stages according to the post-harvest physiological state of Akizuki pears and adjusting the controlled atmosphere parameters accordingly, and employing an intermittent scheme combining initial fumigation upon arrival with periodic supplementary fumigation, achieves precise control over the entire storage process of Akizuki pears. This effectively solves the technical problems of existing technologies where constant controlled atmosphere cannot match the physiological needs of fruits at different stages and the limited effective period of a single 1-methylcyclopropene fumigation. It extends the effective storage period by more than 30 days compared to existing constant controlled atmosphere schemes, and maintains better fruit quality.

[0033] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.

Claims

1. A storage and preservation method combining dynamic modified atmosphere storage with intermittent 1-MCP fumigation, characterized in that, Includes the following steps: After harvesting, keep the stem and stalk of the Akizuki pear and soak it in a preservative solution for 5-10 minutes in the dark. Then take it out and let it dry. Place the soaked Akizuki pear in a low temperature environment of 4-10℃ and relative humidity of 85-90% and store it under artificial atmosphere conditions. The controlled atmosphere storage is divided into three stages according to the storage period, and the gas parameters are dynamically adjusted in each stage as follows: the first 30 days of storage is the early stage, maintaining an oxygen concentration of 5%–8%, a carbon dioxide concentration of 1%–2%, and nitrogen as the balance gas; the 31st–90th days of storage is the middle stage, adjusting to an oxygen concentration of 2%–4%, a carbon dioxide concentration of 2%–4%, and nitrogen as the balance gas; the 91st day of storage to the end of storage is the late stage, adjusting to an oxygen concentration of 1%–2.5%, a carbon dioxide concentration of 3%–5%, and nitrogen as the balance gas. During storage, the first 1-methylcyclopropene fumigation is carried out upon entry into the warehouse, and thereafter fumigation is carried out every 25 to 35 days. The concentration of 1-methylcyclopropene in each fumigation is 0.5 to 2 μL / L, and the fumigation time is 12 to 24 hours.

2. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 1, characterized in that, The preservative solution contains the following concentrations of raw materials: melatonin 0.5–2 mmol / L, citric acid 0.05–0.2 g / L, ferrous sulfate 0.02–0.3 g / L, calcium chloride 0.5–2 g / L, surfactant 0.1–0.5 g / L, with the remainder being water.

3. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 2, characterized in that, The surfactant is either laurate or monooleate.

4. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 1, characterized in that, The first 1-methylcyclopropene fumigation is completed within 24 hours of the warehouse entry, and each subsequent supplementary fumigation is completed within 48 hours before or after the corresponding time point.

5. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 1, characterized in that, The switching of gas parameters at each stage is done gradually, over a period of 3 to 5 days.

6. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 1, characterized in that, The low-temperature environment is 5–7°C and the relative humidity is 85–90%.

7. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 1, characterized in that, The initial oxygen concentration was 6%–7%, and the carbon dioxide concentration was 1%–1.5%.

8. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 1, characterized in that, The intermediate-term oxygen concentration is 3%–4%, and the carbon dioxide concentration is 2.5%–3%.

9. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 1, characterized in that, The oxygen concentration in the later stage is 1% to 2%, and the carbon dioxide concentration is 4% to 5%.

10. The storage and preservation method of dynamic modified atmosphere combined with intermittent 1-MCP fumigation according to claim 1, characterized in that, The requirement to supplement fumigation every 25-35 days is now changed to supplementing fumigation every 30 days.

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