Post-harvest variable-temperature storage method for kiwi fruits

Abstract

The invention discloses a postharvest variable-temperature storage method for kiwi fruits, which relates to the technical field of fruit and vegetable preservation and comprises the following steps of fruit picking, warehousing and pre-cooling, variable-temperature storage and ventilation. According to the method, stable ripening of the kiwi fruits can be achieved through variable-temperature treatment, the problem of fruit quality easily caused by a traditional chemical ripening method is avoided, the kiwi fruits ripened through the method are uniform in after-ripening, bright in color and luster and excellent in taste, the fruit quality is remarkably improved, the fresh-keeping period of the kiwi fruits is further remarkably prolonged, and the kiwi fruits are suitable for large-scale popularization and application. According to the method, the loss of the kiwi fruits in the postharvest treatment and storage process can be remarkably reduced through scientific temperature-variable ripening and storage management, and the economic benefit is improved.

Description

Technical Field

[0001] The invention relates to the technical field of fruit and vegetable preservation, and in particular to a temperature-variable storage method for post-harvest kiwifruit. Background Art

[0002] Kiwi, also known as kiwi fruit, is a perennial deciduous woody vine. It is popular for its sweet and sour taste, low calories, high vitamin C, dietary fiber and various mineral nutrients. It has now become one of the important types of fruit.

[0003] As a perishable fruit, kiwifruit is easily affected by factors such as temperature, humidity, and gas concentration during post-harvest storage, which can lead to problems such as fruit quality degradation and decay. Although traditional low-temperature storage technology can delay kiwifruit aging to a certain extent, it has defects such as short shelf life and large flavor changes. Ice temperature storage technology is an emerging physical preservation method that can effectively extend the shelf life of kiwifruit by storing it in a temperature range near the freezing point of the fruit, but it requires high accuracy in temperature control.

[0004] As a perishable fruit, kiwifruit is easily affected by factors such as temperature, humidity, and gas concentration during post-harvest storage, which can lead to problems such as fruit quality degradation and decay. Although traditional low-temperature storage technology can delay kiwifruit aging to a certain extent, it has defects such as short shelf life and large flavor changes. Ice temperature storage technology is an emerging physical preservation method that can effectively extend the shelf life of kiwifruit by storing it in a temperature range near the freezing point of the fruit, but it requires high accuracy in temperature control. Summary of the invention

[0005] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0006] A method for storing kiwifruit after harvest at variable temperature comprises the following steps:

[0007] S1. Select kiwifruits with moderate maturity and no pests and diseases for harvest, grade them, remove unqualified fruits, pile them in the field for 3 to 4 hours, and transport them back for pre-cooling.

[0008] S2. Install and debug the temperature control system, humidity control system, ventilation system, monitoring components and alarm system components of the storage room to ensure that each system can work normally and coordinate with each other.

[0009] S3. Put the kiwifruit into turnover boxes, with each box containing 9 to 11 kilograms and a height of less than 30 cm. After the field heat dissipates under the shade shed, put them into storage at 4 to 5 in the morning.

[0010] S4. Pre-cool the fruit in a warehouse at 0℃ to 1℃ for 2 to 3 days, stack the fruit when its temperature is close to the storage temperature, quickly transport the pre-treated kiwifruit to the storage room, and turn on the refrigeration equipment to quickly drop the temperature in the storage room to the freezing point of the kiwifruit -0.5℃ to 0℃.

[0011] S5. Use the temperature control system to dynamically control the temperature in the storage room at 0.5℃ to 0.8℃, which is the freezing point of kiwi fruit. The monitoring components and alarm system monitor the temperature, humidity and gas concentration parameters in the storage room in real time, and send out alarm signals in abnormal situations so that timely measures can be taken.

[0012] S6. Ventilation system: Ventilate the room regularly to keep the oxygen concentration between 2% and 3%, the carbon dioxide concentration between 4% and 6%, and the ethylene concentration below 30 micrograms per liter.

[0013] S7. Monitor the temperature, humidity and gas concentration in the storage room in real time through the monitoring component, and automatically adjust the storage conditions according to the monitoring results.

[0014] More preferably, during harvesting in S1, the fruits are picked from the separation layer between the fruit stalk and the fruit, and small fruits, rotten fruits, diseased fruits, deformed fruits and injured fruits are removed.

[0015] More preferably, the fruits are graded according to weight in S1, with the small fruit type starting at 70g to 75g and the large fruit type starting at 80g to 85g.

[0016] More preferably, in the initial storage stage in S5, the temperature is 0°C to 2°C to mitigate chilling injury to the fruit, and as the storage time increases, the temperature is gradually lowered to -0.5°C to -1°C to extend the shelf life.

[0017] More preferably, in the initial stage of storage in S5, the temperature is set at -0.8°C to -0.5°C, and as the storage time increases, the temperature is gradually lowered to -1.2°C to 0.8°C to extend the shelf life.

[0018] It is further preferred that the ventilation system in S6 ventilates once every 5 to 7 days, and does so at night or in the early morning to reduce the impact on the temperature in the storage room.

[0019] More preferably, an adsorption-type preservative is placed in the turnover box in S3, and the preservative is replaced regularly.

[0020] Further preferably, the monitoring component in S7 includes a sensor network unit, a data acquisition unit, a processing unit, and a control execution unit, and the monitoring component is connected to a temperature control system, a humidity control system, a ventilation system, and an alarm system component.

[0021] Compared with the prior art, the present invention has the following advantages: through temperature-changing treatment, the stable ripening of kiwifruit can be achieved, and the fruit quality problems easily caused by the traditional chemical ripening method are avoided. The kiwifruit fruits ripened by the method of the present invention are uniformly ripened, bright in color, and excellent in taste, and the fruit quality is significantly improved. Furthermore, the shelf life of kiwifruit is significantly extended, the loss due to decay is reduced, and the original flavor and nutritional components of kiwifruit are maintained. Furthermore, the market value and competitiveness of kiwifruit are improved, and the energy consumption and cost during storage are reduced. Through scientific temperature-changing ripening and storage management, the loss of kiwifruit fruits during post-harvest processing and storage can be significantly reduced, thereby improving economic benefits. DETAILED DESCRIPTION

[0022] A method for storing kiwifruit after harvest at variable temperature comprises the following steps:

[0023] S1. Select kiwifruits with moderate maturity and no pests and diseases for harvest, grade them, remove unqualified fruits, pile them in the field for 3 to 4 hours, and transport them back for pre-cooling.

[0024] S2. Install and debug the temperature control system, humidity control system, ventilation system, monitoring components and alarm system components of the storage room to ensure that each system can work normally and coordinate with each other.

[0025] S3. Put the kiwifruit into turnover boxes, with each box containing 9 to 11 kilograms and a height of less than 30 cm. After the field heat dissipates under the shade shed, put them into storage at 4 to 5 in the morning.

[0026] S4. Pre-cool the fruit in a warehouse at 0℃ to 1℃ for 2 to 3 days, stack the fruit when its temperature is close to the storage temperature, quickly transport the pre-treated kiwifruit to the storage room, and turn on the refrigeration equipment to quickly drop the temperature in the storage room to the freezing point of the kiwifruit -0.5℃ to 0℃.

[0027] S5. Use the temperature control system to dynamically control the temperature in the storage room at 0.5℃ to 0.8℃, which is the freezing point of kiwi fruit. The monitoring components and alarm system monitor the temperature, humidity and gas concentration parameters in the storage room in real time, and send out alarm signals in abnormal situations so that timely measures can be taken.

[0028] S6. Ventilation system: Ventilate the room regularly to keep the oxygen concentration between 2% and 3%, the carbon dioxide concentration between 4% and 6%, and the ethylene concentration below 30 micrograms per liter.

[0029] S7. Monitor the temperature, humidity and gas concentration in the storage room in real time through the monitoring component, and automatically adjust the storage conditions according to the monitoring results.

[0030] The temperature-variable treatment can achieve stable ripening of kiwifruit, and the fruit quality problems easily caused by the traditional chemical ripening method are avoided. The kiwifruit fruits ripened by the method of the present invention are uniformly ripened, bright in color, and excellent in taste, and the fruit quality is significantly improved. Furthermore, the shelf life of the kiwifruit is significantly extended, the rot loss is reduced, and the original flavor and nutritional components of the kiwifruit are maintained. Furthermore, the market value and competitiveness of the kiwifruit are improved, and the energy consumption and cost in the storage process are reduced. Through scientific temperature-variable ripening and storage management, the loss of kiwifruit fruits in the post-harvest processing and storage process can be significantly reduced, thereby improving the economic benefits.

[0031] Embodiment 1

[0032] A method for storing kiwifruit after harvest at variable temperature comprises the following steps:

[0033] S1. Select kiwifruits with moderate maturity and no pests and diseases for harvest, grade them, remove unqualified fruits, pile them in the field for 3 hours, and transport them back for pre-cooling.

[0034] S2. Install and debug the temperature control system, humidity control system, ventilation system, monitoring components and alarm system components of the storage room to ensure that each system can work normally and coordinate with each other.

[0035] S3. Put the kiwifruit into turnover boxes, with 10 kg in each box and a height of less than 30 cm. After the field heat dissipates under the shade shed, put them into storage between 4 and 5 in the morning.

[0036] S4. Pre-cool the fruit in a warehouse at 0℃ to 1℃ for 2 days, stack the fruit when its temperature is close to the storage temperature, quickly transport the pre-treated kiwifruit to the storage room, and turn on the refrigeration equipment to quickly drop the temperature in the storage room to the freezing point of kiwifruit -0.5℃.

[0037] S5. Use the temperature control system to dynamically control the temperature in the storage room at 0.5°C, the freezing point of kiwi fruit. The monitoring components and alarm system monitor the temperature, humidity and gas concentration parameters in the storage room in real time, and send out alarm signals in abnormal situations so that timely measures can be taken.

[0038] S6. Ventilation system: Ventilate the room regularly to keep the oxygen concentration at 2%, the carbon dioxide concentration at 4%, and the ethylene concentration below 30 micrograms / liter.

[0039] S7. Monitor the temperature, humidity and gas concentration in the storage room in real time through the monitoring component, and automatically adjust the storage conditions according to the monitoring results.

[0040] Embodiment 2

[0041] A method for storing kiwifruit after harvest at variable temperature comprises the following steps:

[0042] S1. Select kiwifruits with moderate maturity and no pests and diseases for harvest, grade them, remove unqualified fruits, pile them in the field for 4 hours, and transport them back for pre-cooling.

[0043] S2. Install and debug the temperature control system, humidity control system, ventilation system, monitoring components and alarm system components of the storage room to ensure that each system can work normally and coordinate with each other.

[0044] S3. Put the kiwifruit into turnover boxes, with 11 kg in each box and a height of less than 30 cm. After the field heat dissipates under the shade shed, put them into storage at 5 am.

[0045] S4. Pre-cool the fruit in a warehouse at 0℃ to 1℃ for 3 days, stack the fruit when its temperature is close to the storage temperature, quickly transport the pre-treated kiwifruit to the storage room, and turn on the refrigeration equipment to quickly drop the temperature in the storage room to 0℃, the freezing point of the kiwifruit.

[0046] S5. Use the temperature control system to dynamically control the temperature in the storage room at 0.8°C, the freezing point of kiwi fruit. The monitoring components and alarm system monitor the temperature, humidity and gas concentration parameters in the storage room in real time, and send out alarm signals in abnormal situations so that timely measures can be taken.

[0047] S6. Ventilation system: Ventilate the room regularly to keep the oxygen concentration at 3%, the carbon dioxide concentration at 6%, and the ethylene concentration below 30 micrograms / liter.

[0048] S7. Monitor the temperature, humidity and gas concentration in the storage room in real time through the monitoring component, and automatically adjust the storage conditions according to the monitoring results.

[0049] Specifically, during harvesting in S1, the fruits are picked from the abscission layer between the fruit stalk and the fruit, and small fruits, rotten fruits, diseased fruits, deformed fruits and injured fruits are removed.

[0050] Specifically, in S1, the fruits are graded according to weight, with small fruits starting at 70g to 75g and large fruits starting at 80g to 85g.

[0051] Furthermore, in S4, the pretreated kiwifruit is transported to a storage warehouse, and refrigeration is turned on to reduce the respiration and metabolic activities of the fruit.

[0052] Exemplarily, at the initial stage of storage in S5, the temperature is 0°C to 2°C to mitigate chilling injury to the fruit, and as the storage time increases, the temperature is gradually lowered to -0.5°C to -1°C to extend the shelf life.

[0053] Exemplarily, at the initial stage of storage in S5, the temperature is set at -0.8°C to -0.5°C, and as the storage time increases, the temperature is gradually lowered to 1.2°C to 0.8°C to extend the shelf life.

[0054] Specifically, the ventilation system in S6 is ventilated once every 5 to 7 days, and is carried out at night or in the early morning to reduce the impact on the temperature in the storage room.

[0055] Specifically, an adsorption-type preservative is placed in the turnover box in S3, and the preservative is replaced regularly. Furthermore, the adsorption-type preservative can be an ethylene adsorbent made by soaking vermiculite or perlite as a carrier in a saturated potassium permanganate solution. Preferably, ozone can be used to degrade ethylene for preservation, and the preservative is replaced regularly.

[0056] Specifically, the monitoring component in S7 includes a sensor network unit, a data acquisition unit, a processing unit, and a control execution unit, and the monitoring component is connected to the temperature control system, the humidity control system, the ventilation system, and the alarm system components.

[0057] Furthermore, the temperature in the storage room is monitored in real time by the temperature control system, and the data is uploaded to the data acquisition unit and the processing unit. Specifically, when the temperature exceeds the preset range, for example, the suitable temperature for kiwi storage is -0.5°C to 0.5°C, the system will automatically start or shut down the refrigeration equipment to adjust the temperature.

[0058] Furthermore, the humidity control system is used to monitor the humidity level in the storage room. For example, when kiwifruit is stored, the relative humidity should be maintained above 90% to prevent water loss and wrinkling of the skin. The temperature control system will automatically adjust the humidification or dehumidification equipment according to the reading of the humidity sensor to maintain a suitable humidity environment.

[0059] Furthermore, the control execution unit automatically adjusts the environmental conditions in the storage room according to the data analysis results, such as controlling the temperature by adjusting the refrigeration equipment, adjusting the humidity by the humidification or dehumidification equipment, and adjusting the gas concentration by filling nitrogen or releasing oxygen.

[0060] Furthermore, the ventilation system monitors the oxygen and carbon dioxide concentrations in the storage room. Furthermore, in order to ensure that the kiwifruit is stored in a low-oxygen and high-carbon dioxide environment to extend the shelf life, the system will adjust the operating status of the nitrogen filling or oxygen release equipment in real time to maintain the oxygen concentration between 2% and 3%, and the carbon dioxide concentration between 3% and 5%. At the same time, the system will also monitor the ethylene concentration to ensure that it is lower than 0.02ppm to prevent the kiwifruit from ripening and rotting prematurely.

[0061] Furthermore, in S7, the temperature in the storage room is automatically adjusted according to a preset temperature change strategy to achieve precise control and dynamic change of temperature. Furthermore, the data collected by the sensor network unit is transmitted to the data acquisition unit and the processing unit via wired or wireless means, and the unit centrally processes and analyzes the data to determine whether the current storage environment meets the preset conditions.

[0062] Furthermore, when the temperature, humidity or gas concentration in the storage room exceeds the preset range and lasts for a certain period of time (such as set to several minutes to several hours), the alarm system triggers an alarm. The alarm form includes but is not limited to sound alarms, flashing lights, and text messages or email notifications sent to managers. After receiving the alarm, the manager can quickly view the specific parameters through the remote monitoring interface and take corresponding treatment measures.

[0063] Furthermore, when the temperature, humidity, and gas concentration in the storage room are monitored to be beyond the preset range, the alarm system and communication module will immediately sound an alarm and notify the management personnel via mobile phone text messages, emails, or remote monitoring interfaces.

[0064] Based on the changes in physiological and biochemical characteristics of kiwifruit during ripening, especially the changes in sugar, acidity, hardness and characteristic compounds (such as anthocyanins), a multi-parameter comprehensive evaluation model is designed. The model will combine spectral analysis, chromatographic analysis and machine learning algorithms to accurately predict the maturity of kiwifruit.

[0065] Specifically, sugar content: The sugar content of kiwifruit is one of the important indicators to measure its maturity. As the fruit matures, the sugar content will gradually increase.

[0066] Acidity: As the fruit ripens, the acidity usually decreases gradually, in contrast to the changes in sugar content.

[0067] Hardness: Fruit hardness is an important criterion for judging whether kiwifruit is suitable for picking and eating. As the maturity increases, the hardness will gradually decrease.

[0068] Content of characteristic compounds: Changes in the content of pigments such as anthocyanins can also reflect the maturity of kiwifruit.

[0069] Detection and analysis

[0070] 1. Use ultraviolet, visible or infrared spectroscopy technology to quickly and non-destructively detect the reflection spectrum or transmission spectrum of the kiwifruit surface, and infer the sugar and acidity chemical composition information inside the fruit through the change of absorbance or reflectance at characteristic wavelengths. Specifically, it includes a spectrometer, a light source, a detector, and optical fiber components to collect spectral data of kiwifruit.

[0071] 2. Use high performance liquid chromatography (HPLC) technology to conduct qualitative and quantitative analysis of characteristic compounds in kiwifruit, such as determining the types and contents of anthocyanins, for the separation and quantitative analysis of characteristic compounds in kiwifruit.

[0072] 3. Combined with the above detection data, BP neural network and random forest machine learning algorithm are used to establish a kiwifruit maturity prediction model. By training and learning a large amount of sample data, the prediction accuracy and generalization ability of the model are improved. Specifically, it includes computers, data processing software and machine learning algorithm libraries for processing spectral and chromatographic data, and building and training prediction models.

[0073] Testing process

[0074] 1. Select representative kiwifruit samples, remove surface dust and impurities, and maintain sample integrity.

[0075] 2. Use the spectrum acquisition system to perform spectral scanning on the kiwifruit to obtain its reflection spectrum or transmission spectrum data.

[0076] 3. After appropriate treatment of the kiwifruit samples, chromatographic analysis was performed using a high performance liquid chromatograph to determine the content of characteristic compounds.

[0077] 4. Input the spectral and chromatographic data into the data processing and analysis system for preprocessing, feature extraction and model prediction.

[0078] 5. Based on the output results of the prediction model, determine the maturity level of the kiwifruit or give a specific maturity prediction value.

[0079] To infer the storage time of kiwifruit under different storage conditions and present it in tabular form.

[0080] Table 1: Comparison of kiwifruit storage temperature and storage time

[0081]

[0082] Condition 1: Colder temperature, higher humidity, and lower oxygen concentration can theoretically extend the storage time, but care should be taken to avoid frost damage and mildew caused by excessive humidity.

[0083] Condition 2: Both temperature and humidity are set to moderate values, and the oxygen concentration is also moderate. Under this condition, the storage time range may be wider, depending on the kiwifruit variety and management level.

[0084] Condition three: slightly higher temperature and slightly higher oxygen concentration (upper limit) may result in slightly shorter storage time.

[0085] Condition 4: Keeping the temperature and humidity unchanged but adjusting the gas concentration (reducing oxygen and slightly increasing carbon dioxide) may extend the storage time, but it needs to be monitored to avoid anaerobic respiration problems.

[0086] Condition 5: Simultaneously increasing humidity and adjusting gas concentration (moderate oxygen, slightly lower carbon dioxide) can theoretically significantly extend storage time, but this requires strict management and monitoring to ensure optimal storage conditions.

[0087] Through the above theoretical model design and mechanism implementation scheme, the rapid and accurate detection of kiwifruit maturity can be achieved, which has the advantages of non-destructive, rapid and efficient, and can meet the needs of the kiwifruit industry for fruit quality control. At the same time, with the continuous advancement of technology and continuous optimization of the model, the detection accuracy and stability will be further improved, providing more powerful technical support for the development of the kiwifruit industry.

[0088] This specific embodiment is merely an explanation of the invention and is not a limitation of the invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as they are within the scope of protection of the invention, they are protected by patent law.

Claims

1. A method for storing kiwifruit after harvest at variable temperature, characterized in that: The following steps are involved: S1. Select kiwifruits with moderate maturity and no pests and diseases for harvest, grade them, remove unqualified fruits, pile them in the field for 3 to 4 hours, and transport them back for pre-cooling; S2. Install and debug the temperature control system, humidity control system, ventilation system, monitoring components and alarm system components of the storage room to ensure that each system can work normally and coordinate with each other; S3. Put the kiwifruit into turnover boxes, each box contains 9 to 11 kg, the height is less than 30 cm, and put them into storage at 4 to 5 am after the field heat dissipates under the shade shed; S4. Pre-cool the fruit in a 0℃ to 1℃ warehouse for 2 to 3 days, stack the fruit when the temperature is close to the storage temperature, quickly transport the pre-treated kiwifruit to the storage room, and turn on the refrigeration equipment to quickly drop the temperature in the storage room to the freezing point of the kiwifruit -0.5℃ to 0℃; S5. Using the temperature control system, the temperature in the storage room is dynamically controlled at 0.5°C to 0.8°C, which is the freezing point of the kiwi fruit. The monitoring component and the alarm system monitor the temperature, humidity and gas concentration parameters in the storage room in real time, and send out an alarm signal in abnormal situations so that timely measures can be taken; S6. Ventilation system: Regular ventilation and ventilation should be carried out to keep the oxygen concentration in the storage room between 2% and 3%, the carbon dioxide concentration between 4% and 6%, and the ethylene concentration below 30 micrograms / liter; S7. Monitor the temperature, humidity and gas concentration in the storage room in real time through the monitoring component, and automatically adjust the storage conditions according to the monitoring results.

2. The method for storing kiwifruit after harvest at variable temperature according to claim 1, characterized in that: During harvesting in S1, the fruits are picked from the fruit stalk and the abscission layer of the fruit, and small fruits, rotten fruits, diseased fruits, deformed fruits and injured fruits are removed.

3. The method for storing kiwifruit after harvest at variable temperature according to claim 1, characterized in that: In the S1, the fruits are graded according to weight, with small fruits starting at 70g to 75g and large fruits starting at 80g to 85g.

4. The method for storing kiwifruit after harvest at variable temperature according to claim 1, characterized in that: In the initial storage stage of S5, the temperature is 0°C to 2°C to mitigate the chilling injury of the fruit. As the storage time increases, the temperature is gradually reduced to -0.5°C to -1°C to extend the shelf life.

5. The method for storing kiwifruit after harvest at variable temperature according to claim 1, characterized in that: In the initial stage of storage in S5, the temperature is set at -0.8°C to -0.5°C, and as the storage time increases, the temperature is gradually lowered to -1.2°C to 0.8°C to extend the shelf life.

6. The method for storing kiwifruit after harvest at variable temperature according to claim 1, characterized in that: The ventilation system in S6 is ventilated once every 5 to 7 days, and is carried out at night or in the early morning to reduce the impact on the temperature in the storage room.

7. The method for storing kiwifruit after harvest at variable temperature according to claim 1, characterized in that: In the turnover box in S3, an adsorption type preservative is placed, and the preservative is replaced regularly.

8. The method for storing kiwifruit after harvest at variable temperature according to claim 1, characterized in that: The monitoring component in S7 includes a sensor network unit, a data acquisition unit, a processing unit, and a control execution unit, and the monitoring component is connected with a temperature control system, a humidity control system, a ventilation system, and an alarm system component.

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