Freshness keeping method and freshness keeping system for fruit and vegetables

Abstract

To realize a method capable of keeping freshness of fruit and vegetables.SOLUTION: A freshness keeping method for fruit and vegetables prolongs by 25% or more a period during which 95% or more of a weight of fruit and vegetables before being irradiated with light is retained, by means of irradiation of light having peak frequency in a range of 256 nm or longer and 297 nm or shorter to fruit and vegetables picked up within 24 hours.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a freshness preservation method and a freshness preservation system for maintaining the freshness of fruits and vegetables. [Background technology]

[0002] There is a known method for maintaining the freshness of fruits and vegetables by irradiating them with light after harvesting. Patent Document 1 discloses a method for maintaining the freshness of fruits and vegetables, including strawberries, by irradiating them with near-infrared light of 700 nm to 2500 nm, for example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-093433 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for methods that can maintain the freshness of fruits and vegetables using wavelengths other than near-infrared light. [Means for solving the problem]

[0005] A method for maintaining the freshness of fruits and vegetables disclosed in one embodiment is a method for extending by 25% or more the time for which fruits and vegetables are maintained at 95% or more of their weight before exposure to light by irradiating the fruits and vegetables within 24 hours after harvest with light having a peak wavelength in the range of 256 nm or more and 297 nm or less. Effect of the Invention

[0006] In at least one of the one or more inventions disclosed in the embodiments, a method for maintaining the freshness of fruits and vegetables can be realized. [Brief description of the drawings]

[0007] [Figure 1]FIG. 1 shows the results of the storage test in Experiment 1. [Figure 2A] FIG. 2A is a photograph showing the state of pores observed with an optical microscope. [Figure 2B] FIG. 2B is a photograph showing the state of pores observed with an optical microscope. [Diagram 3] FIG. 3 shows the results of the storage test in Experiment 2. [Figure 4] FIG. 4 shows the results of the storage test in Experiment 3. [Diagram 5] FIG. 5 shows the results of the storage test in Experiment 4. [Figure 6] FIG. 6 is a diagram showing the results of hardness measurement using the samples of Experiment 4. [Figure 7] FIG. 7 shows the results of antioxidant activity measurement using samples from Experiment 4. [Figure 8] FIG. 8 shows the measurement results of the fisetin content in the samples of Experiment 4. [Figure 9] FIG. 9 is a diagram showing the measurement results of the nitrate nitrogen concentration using the samples of Experiment 4. [Figure 10] FIG. 10 is a diagram showing the spectra of the light sources used in Experiments 1 to 10. As shown in FIG. [Figure 11] FIG. 11 shows the results of the storage test in Experiment 5. [Figure 12] FIG. 12 shows the results of the storage test in Experiment 6. [Figure 13] FIG. 13 shows the results of the storage test in Experiment 7. [Figure 14] FIG. 14 shows the results of the storage test in Experiment 8. [Figure 15] FIG. 15 shows the results of the storage test in Experiment 9. [Figure 16] FIG. 16 shows the results of the storage test in Experiment 10. [Figure 17] FIG. 17 is a diagram showing a light irradiation device that can be used in this embodiment. [Figure 18] FIG. 18 is a system configuration diagram of a freshness preservation system according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] From one perspective, the present invention is a method for maintaining the freshness of fruits and vegetables, which is characterized by irradiating fruits and vegetables within 24 hours after harvest with light having a peak wavelength in the range of 256 nm or more and 297 nm or less, thereby extending by 25% or more the time during which the fruits and vegetables are maintained at 95% or more of their weight before exposure to the light.

[0009] As shown in the experimental examples described below, the present invention is based on the new finding that it is possible to extend the freshness period of fruits and vegetables such as strawberries by irradiating them with light of about 280 nm. In the distribution and storage of fruits and vegetables, maintaining freshness is extremely important because it affects their commercial value. For example, there is a need to extend the freshness period of fruits and vegetables such as strawberries, which do not keep well on the shelf, even by one day.

[0010] The freshness of fruits and vegetables can be evaluated, for example, by the amount of weight loss (in other words, the amount of transpiration). For many fruits and vegetables, if the weight of the fruit or vegetable decreases by 5% or more from the weight at harvest, the quality as a product is significantly impaired. Therefore, in this specification, maintaining freshness is defined as maintaining 95% or more of the weight of the fruit or vegetable within 24 hours after harvest. The number of days for which 95% weight is maintained is used as a freshness index.

[0011] In this embodiment, the fruits and vegetables are irradiated with light in a wavelength range that is effective for extending the time during which they retain at least 95% of their weight, that is, light in a range of 256 nm to 305 nm, more specifically light in a range of 256 nm to 297 nm, more specifically light in a range of 270 nm to 297 nm, which also has a sterilizing effect.

[0012] The light in the above wavelength range may be light extracted by using an optical filter from a light source that emits light having a wide wavelength spectrum, such as a halogen lamp. It may also include light from a light emitting diode (LED) or a laser diode (LD) as a light source, or may consist of such light alone. The use of an LED or LD is preferable from the viewpoint of energy efficiency and economy due to its energy intensiveness, low heat generation, low power consumption, and long life. In addition, it is easy to control or manage the amount of irradiation. By using an LED with a lens, the area to be irradiated can be efficiently irradiated.

[0013] The amount of irradiation (also referred to as the cumulative amount of light) of the above wavelengths is not particularly limited as long as it is an amount effective for extending the time for which the fruit or vegetable is maintained at 95% or more, more preferably 96%, and more preferably 97% or more of its weight. The specific amount of irradiation may vary depending on the type and variety of the fruit or vegetable used, but a specific amount of irradiation is, for example, 5 mJ / cm. 2 More than 100mJ / cm 2 Less than 5 mJ / cm, preferably 5 mJ / cm 2 More than 64mJ / cm 2 Less than or equal to 5 mJ / cm 2 More than 60mJ / cm 2 This irradiation amount is within the range in which the freshness-maintaining effect was confirmed in the experimental example of strawberries described later, but it is considered to be applicable to other fruits and vegetables. In this specification, the "irradiation amount" refers to the irradiation amount on the light-receiving surface of the fruit or vegetable.

[0014] The illuminance of the light having the above wavelength is also not particularly limited as long as it is an amount effective for extending the time for which the fruit or vegetable is maintained at 95% or more, more preferably 96% or more, and more preferably 97% or more of its weight. For example, 0.1 mW / cm 2 More than 100mW / cm 2 Less than 0.1 mW / cm, preferably 0.1 mW / cm 2 More than 50mW / cm 2 Less than or equal to 0.3 mW / cm 2 More than 50mW / cm 2This illuminance is within the range in which the freshness-maintaining effect was confirmed in the experimental example on strawberries described below, but it is believed to be applicable to other fruits and vegetables.

[0015] The irradiation time of light with the above wavelengths is not particularly limited as long as it is effective in extending the time during which 95% or more of the weight of the fruit or vegetable is maintained, and may be, for example, 0.1 to 180 seconds, preferably 2 to 180 seconds, more preferably 2 to 18 seconds. If the irradiation time is too short or too long, the effect of maintaining the weight may not be achieved.

[0016] The time for which the time during which 95% or more of the fruit or vegetable weight is maintained is preferably extended by 25% or more (i.e., 1.25 times) compared to the case of non-irradiation. More preferably, it can be extended by 30% or more, and even more preferably, it can be extended by 50% or more. The time for which the time during which 95% or more of the fruit or vegetable weight is maintained can be calculated by measuring the weight of a light-irradiated sample in which the present invention is implemented and a non-irradiated sample in which the present invention is not implemented. The light-irradiated sample and the non-irradiated sample are the same fruit or vegetable harvested on the same day at the same cultivation field, and other than the presence or absence of light irradiation, for example, the storage conditions are the same. The storage conditions may be any conditions suitable for the fruit or vegetable.

[0017] The light may be irradiated directly onto the surface of the fruit or vegetable, or may be irradiated while the fruit or vegetable is placed in a light-transmitting container. The container may be light-transmitting, and may have an opening for the light to enter.

[0018] The light irradiation may be performed with the fruit or vegetable placed on a mounting member having a mounting surface with an average reflectance of the irradiated light of 20% or more, preferably 30% or more, and more preferably 40% or more. The mounting member may be, for example, a tray or container for storing the fruit or vegetable.

[0019] The light of the above wavelengths may be irradiated as continuous light or as intermittent light (for example, pulsed light). The light of the above wavelengths may be irradiated alone or in combination with light of other wavelengths. In this case, the two types of light may be irradiated simultaneously (as composite light or mixed light) or alternately.

[0020] The light irradiation can be performed within 24 hours, preferably within 12 hours, more preferably within 6 hours after harvesting. The shorter the time after harvesting, the higher the sensitivity of the fruits and vegetables to light, which is preferable. For example, after harvesting, the fruits and vegetables may be placed in a tray or container and irradiated with light from above. In addition, in order to irradiate the back side of the fruits and vegetables (i.e., the side in contact with the placement surface of the storage container) with light, the storage container may have a small opening so that the fruits and vegetables do not fall to the bottom. Alternatively, the bottom of the storage container may be made of a net. Alternatively, the bottom of the storage container may have a light-transmitting window. The light irradiation may be of a conveyor type or a batch type. For example, an irradiation device capable of irradiating light from above a conveyor used in the sorting process of the fruits and vegetables can be used.

[0021] Alternatively, the fruits and vegetables held for harvesting may be inserted into the light irradiation device for a few seconds to irradiate the fruits and vegetables with light before being placed in a designated location. Also, the harvesting robot may be equipped with a light irradiation device, and harvesting and light irradiation may be performed almost simultaneously. Almost simultaneously here means that irradiation begins within one minute after harvesting. This allows light irradiation to be performed immediately after harvesting.

[0022] It is also believed that the freshness-maintaining effect can be obtained by irradiating the fruit with light immediately before harvesting or during cultivation, rather than after harvesting. "Immediately before harvesting" here refers to the period from one week before harvesting to harvesting.

[0023] Light irradiation may be performed after sorting. For example, by sorting by ripeness or blemishes, and selecting fruits and vegetables that are not overripe and have few blemishes and then irradiating them with light, the freshness maintenance period can be extended more effectively. Overripe fruits and vegetables have soft skins that are already prone to blemishes before light irradiation, so the freshness maintenance effect tends to be weak even if they are irradiated with light. In addition, since blemished fruits and vegetables may be unsuitable for sale, it is preferable to exclude such fruits and vegetables from being subjected to light irradiation in advance. This makes it possible to select fruits and vegetables that have a long freshness maintenance period after light irradiation, making them suitable for export.

[0024] The ripeness may be determined, for example, by checking the color of the fruit or vegetable. The color may be quantified by any method depending on the type of fruit or vegetable. Alternatively, the ripeness may be determined by measuring the hardness of the peel. The hardness may be measured by a contact-type needle-type fruit hardness meter or a non-contact measuring device. An example of a non-contact measuring device is a method of measuring hardness by applying compressed air to the fruit or vegetable and measuring the change in indentation over time with a laser distance sensor. This principle is similar to that of an intraocular pressure measuring device. The presence or absence of scratches may be measured by observing with a camera on the fruit sorting machine.

[0025] For non-ripening fruits and vegetables, those with high sugar content may be selected. The sugar content can be measured using a predetermined non-contact sugar content meter.

[0026] If the container for shipping to consumers, such as a pack, is light-transmitting, the material may be irradiated with light while still in the container.

[0027] In the present specification, the fruits and vegetables are not particularly limited. For example, the fruits and vegetables include plants of the Brassicaceae family (particularly Brassica genus and Radish genus), Solanaceae family (particularly Solanaceae genus), Berberidaceae family (particularly Ophiopogon genus), Theaceae family (particularly Theaceae genus), Fabaceae family (particularly Glycine max genus), Rutaceae family (particularly Citrus genus), Vitaceae family (particularly Vitis genus), Rosaceae family (particularly Rubus genus), Asteraceae family (particularly Lamiaceae genus), and Lamiaceae family (particularly Perilla genus). Specific examples of the fruits and vegetables that can be used in the present invention include Arabidopsis thaliana, Podophyllum, tea plant, soybean, sudachi, grape, cabbage, broccoli, komatsuna, bok choy, radish, turnip, tomato, eggplant, strawberry, lettuce, banana, avocado, apple, peach, blueberry, cherry, mango, fig, perilla, and cucumber.

[0028] In this specification, the fruits and vegetables may be fruits and vegetables having UVR8 photoreceptors. As will be described in detail in the experimental examples below, there are at least two mechanisms by which UV irradiation can maintain freshness. One of them is thought to be due to the fact that UV irradiation makes it easier for stomata to close, thereby reducing water evaporation. The other is thought to be due to the fact that UV irradiation inhibits the softening of the skin, thereby reducing water evaporation. Both of these mechanisms are related to the UVR8 photoreceptor, which is a receptor for ultraviolet rays. Since land plants and green algae, including the above-mentioned fruits and vegetables, have UVR8 photoreceptors, it is thought that the reduction in water evaporation due to the maintenance of stomata closure and skin hardness is in principle applicable not only to strawberries but also to post-harvest fruits and vegetables having UVR8 photoreceptors.

[0029] According to the experimental results described below, when strawberries are irradiated with light having a peak wavelength of 280 nm, the UVR8 photoreceptor responds to the UV rays, and in addition to the above-mentioned effects, the DPPH radical scavenging activity value and fisetin content, which contribute to antioxidant properties, are increased, and the nitrate nitrogen concentration is reduced. Therefore, the freshness preservation method of this embodiment can impart functions favorable to human health to fruits and vegetables.

[0030] (Light irradiation device) The light irradiation device may be capable of irradiating fruits and vegetables with light of a specified wavelength. The light irradiation device may be an existing quality inspection device that uses X-rays or infrared rays to which a light-emitting device such as an LED is attached. These inspection devices operate in a protected structure to ensure inspection accuracy and human safety. The structure is such that the worker is not irradiated with the irradiated light, so there is no need to provide a separate light-shielding structure.

[0031] In this embodiment, the ultraviolet light irradiated is invisible to the human eye, so it may be difficult to visually determine whether or not irradiation is in progress. For this reason, for safety reasons, visible light may be irradiated simultaneously with ultraviolet light irradiation. The photon flux density of visible light is, for example, 300 μmol / m 2 / s or less, preferably 100 μmol / m 2 Alternatively, a wavelength conversion member that is excited by ultraviolet light and emits light may be disposed at the location where ultraviolet light is irradiated, so that it is possible to check whether ultraviolet light is being irradiated or not.

[0032] 17 shows an example of a light irradiation device used in this embodiment. The light irradiation device 100 is a batch-type light irradiator, and includes an LED module 10, a stage 90 on which fruits and vegetables 20 as irradiation targets are placed, an LED power supply 30, a sequencer 40, and multiple fans 50. In order to make the internal structure easier to understand, the front door is omitted in the illustration.

[0033] The LED module 10 has LEDs 12, an LED mounting substrate 14, and a heat sink 16. The number of mounted LEDs may be any number that can ensure the required amount of irradiation, and may be, for example, about 100 to 200. The heat sink 16 is a member for dissipating heat generated when the LEDs are driven. Metal materials such as aluminum and copper can be suitably used as the material for the heat sink 16.

[0034] A plurality of fans 50 are provided above the heat sink 16 to cool the heat sink 16. The sequencer 40 can control the output of the LEDs 12 according to a predetermined program, and can also control the fans 50 in conjunction with the driving state of the LEDs 12.

[0035] A jack 80 whose height can be changed vertically is provided below the stage 90, and the structure is such that the distance from the light-emitting surface of the LED 12 to the object to be irradiated can be adjusted. A measuring tape 60 for checking height provided on the side of the stage 90 can measure the distance from the light-emitting surface of the LED 12 to the object to be irradiated.

[0036] Fruit or vegetable 20 is placed directly or indirectly on stage 90. In Fig. 17, fruit or vegetable 20 is placed on stage 90 while being placed on placement surface 72 of tray 70. Light emitted from LED 12 is irradiated in the direction indicated by the arrow in Fig. 17 onto the surface of fruit or vegetable 20.

[0037] (Freshness preservation system) An example of a system (freshness preservation system 1000) using the freshness preservation method of this embodiment will be described. Fruits and vegetables are delivered to consumers, for example, from growers such as farmers to shipping organizations such as agricultural cooperatives, from the shipping organizations to wholesale markets, and from the wholesale markets to retailers such as supermarkets and greengrocers. Alternatively, fruits and vegetables may be delivered to consumers from growers such as farmers to food processors, and from the food processors to retailers such as supermarkets and convenience stores as processed foods. In particular, processed foods that are mass-produced in a particular season, such as strawberries for cakes during the Christmas season, may be stored in large quantities as raw materials at food processors for a certain period of time.

[0038] As shown in Fig. 18, freshness preservation system 1000 has cultivation space 300 (such as farmland or a plant factory) for cultivating fruits and vegetables owned by one or more cultivators 201, and management space 400 for fruits and vegetables owned by user 202 of the freshness preservation method of this embodiment. Management space 400 also has collection space 401 for collecting fruits and vegetables, irradiation space 402 in which light irradiation device 100 is installed and the freshness preservation method of this embodiment is performed on the fruits and vegetables, and storage space 403 for storing the fruits and vegetables on which the freshness preservation method of this embodiment has been performed. Furthermore, management space 400 also has processed food production space 404 for processing the stored fruits and vegetables to make processed foods. Furthermore, user 202 may have cultivation space 405 for cultivating fruits and vegetables himself.

[0039] In the freshness preservation system 1000, a user 202 of a management space 400 collects a plurality of fruits and vegetables cultivated by one or a plurality of growers 201 in a collection space 401, carries the collected plurality of fruits and vegetables to an irradiation space 402, and the light irradiation device 100 irradiates light onto each of the plurality of fruits and vegetables brought there. The plurality of fruits and vegetables irradiated with light by the light irradiation device 100 are stored in a storage space 403 under appropriate temperature control. A required number of fruits and vegetables are carried from the plurality of fruits and vegetables stored in the storage space 403 to a processed food production space 404, where processed foods are produced by processing the fruits and vegetables. The produced processed foods are delivered to a store 500 managed by the user 202 or a store 500 that has a contract with the user 202. The contract between the user 202 and the store 500 may be a normal sales contract or a franchise contract.

[0040] In the freshness preservation method of the present embodiment, it is preferable that the time from harvesting of fruits and vegetables to irradiation with ultraviolet light is short. For example, irradiation with ultraviolet light is preferably performed within 24 hours after harvesting, and more preferably within 12 hours after harvesting. Therefore, it is preferable that the user 202 collects fruits and vegetables from the grower 201 who can transport the fruits and vegetables to the collection space 401 within a predetermined preferable time after harvesting. For example, it is possible to select the grower 201 by setting an upper limit on the straight-line distance from the management space 400 or the collection space 401. For example, the target cultivation space 405 may be within 100 km from the management space 400 or the collection space 401. In addition, since it is preferable to collect the fruits and vegetables within a shorter time from harvesting, it is preferable to collect the fruits and vegetables from the cultivation spaces 300, 405 within a range of 20 km, preferably within 5 km, and more preferably within 1 km from the management space 400 or the collection space 401. Incidentally, even when the user 202 himself grows and harvests fruits and vegetables in the cultivation space 405, it is preferable that the distance from the management space 400 or the collection space 401 to the cultivation space 405 satisfies the above-mentioned condition.

[0041] For example, by collecting fruits and vegetables within a specified time after harvesting (however, the specified time is within 24 hours after harvesting) in a management space 400 which includes a collection space 401 for collecting fruits and vegetables, an irradiation space 402 for irradiating light onto the fruits and vegetables, and a temperature-controlled storage space 403 for storing the fruits and vegetables, light can be irradiated at an early stage of distribution, thereby effectively maintaining the freshness of the fruits and vegetables.

[0042] Fruit and vegetables are collected from the cultivation spaces 300, 405 to a collection space 401. The collection space 401 is preferably temperature controlled. The fruit and vegetables are transported to the collection space 401 by the grower 201, the user 202, or a transporter.

[0043] One or more light irradiation devices 100 are installed in the irradiation space 402. In order to irradiate the fruits and vegetables with light as soon as possible after harvesting, it is preferable that the collection space 401 and the irradiation space 402 are installed in the same building. Furthermore, the collection space 401 may be included in the irradiation space 402. In other words, one space may be both the collection space 401 and the irradiation space 402.

[0044] The irradiation of the fruits and vegetables with ultraviolet light by the light irradiation device 100 is preferably performed within 24 hours, preferably within 12 hours, and more preferably within 6 hours after the fruits and vegetables are harvested. In the irradiation space 402, the light irradiation device 100 performs irradiation of ultraviolet light according to the above-mentioned freshness preservation method.

[0045] The fruits and vegetables irradiated with ultraviolet light by the light irradiation device 100 are stored in a storage space 403. The storage space 403 is preferably installed in the same building as the irradiation space 402. The storage space 403 is preferably not only temperature-controlled but also humidity-controlled. By completing the process from collection to storage of the fruits and vegetables within one facility or factory, the freshness of the fruits can be effectively maintained.

[0046] Before the fruits and vegetables are irradiated with light, an identifier for identifying the fruits and vegetables may be attached to the fruits and vegetables or to a container such as a tray or container in which the fruits and vegetables are stored. The identifier is linked to various information required for light irradiation. By reading the identifier before light irradiation, appropriate light irradiation can be performed. For example, by linking the harvest time with the identifier, fruits and vegetables that have been harvested for more than 24 hours can be excluded from the light irradiation targets, and only fruits and vegetables that have been harvested for less than 24 hours can be irradiated with light. Alternatively, by linking information on the height of the fruits and vegetables with the identifier, the illuminance and irradiation distance can be controlled. Alternatively, by linking with the light irradiation history, it is possible to prevent the fruits and vegetables from being irradiated multiple times by mistake or being shipped without being irradiated.

[0047] The management space 400 may have a processed food production space 404. In the processed food production space 404, for example, fruits and vegetables are cut and processed into jellies, yogurt, Western confectionery, Japanese confectionery, and the like using the fruits and vegetables. As a preferred form of the freshness preservation system 1000, a user 202 who produces and sells processed foods collects and stores the fruits and vegetables. This is because a person who produces processed foods needs to keep a certain amount of stock of ingredients for the production, and it is desirable to maintain the freshness of fruits and vegetables that do not keep well as long as possible. Therefore, it is preferable that the irradiation space 402 and the storage space 403 are installed in the same building as the processed food production space 404 owned by a user who produces and sells processed foods. Note that the expression "installed in the same building" has been used so far, but this meaning does not only mean that they are installed in a single physical building, but also includes that they are installed in one of multiple buildings when multiple buildings are gathered on a site.

[0048] The freshness preservation system 1000 may further include an irradiation space 302 having a light irradiation device 100 within or adjacent to the cultivation space 301. For example, the user 202 may lend the light irradiation device 100 to the cultivator 201, so that the cultivator 201 can set up the irradiation space 302 in or near the cultivation space 301. The cultivator 201 uses the light irradiation device 100 to irradiate light onto fruits and vegetables harvested in the cultivation space 301, and transports the fruits and vegetables that have been irradiated with light, in other words, the fruits and vegetables on which the freshness preservation method has been performed, to the management space 400. The fruits and vegetables transported to the management space 400 are stored in the storage space 403 without the need to perform the freshness preservation method in the management space 400.

[0049] The results of Experiments 1 to 10 will be described in detail below using strawberries, cucumbers, and broccoli as examples. The emission spectra of the 280 nm LED used in Experiments 1 to 4 and Experiments 7 to 10, the 254 nm lamp and 310 nm LED used in Experiment 5, and the 270 nm LED used in Experiment 6 are shown in Fig. 10. As mentioned above, the present invention is not limited to strawberries, cucumbers, and broccoli, but can also be applied to other fruits and vegetables. EXAMPLES

[0050] (Experiment 1) Strawberries that had been harvested for about two hours were irradiated with LED light with a peak wavelength of 280 nm. Pechika Honoka, a perennial strawberry for harvesting in summer and autumn, was used for the strawberries. The strawberries were placed on a wire mesh and irradiated from both sides with LEDs installed above and below. The irradiation conditions, such as the amount of irradiation, illuminance, and irradiation time, are as shown in Table 1.

[0051] [Table 1]

[0052] After light irradiation, eight strawberries for each irradiation condition were placed in food packs and stored in a thermostatic chamber at 15°C. The relative humidity was approximately 60%. The food packs were made of polystyrene resin and were stored with the lids closed. Even when the lids were closed, the food packs were not airtight, allowing air to enter and exit. Before storage (storage days 0), and 2, 3, 4, 5, 6, and 10 days after the start of storage, the food packs were removed from the thermostatic chamber and their weights were measured and their appearances were checked. Weights were measured for each food pack together, and the weights of the food packs measured beforehand were subtracted from the measured values ​​to calculate the weight of 8 strawberries.

[0053] The results are shown in Figure 1. Under conditions 2 and 3, weight loss was significantly reduced compared to condition 1. Calculation of the number of days for which 95% weight was maintained, an index of freshness, showed that while condition 1 showed 4 days, conditions 2 and 3 showed an extension to 8 to 10 days. In other words, conditions 2 and 3 showed 2 to 2.5 times the freshness-maintaining effect compared to condition 1. Furthermore, visual observation showed that conditions 2 and 3 had a glossier appearance than condition 1, even after 10 days of storage. On the other hand, conditions 4 to 6 showed no significant advantage over condition 1. In appearance observation, light scorching of the skin was confirmed after about one day under condition 6. Light scorching here refers to a state in which the skin turns brownish when observed with the naked eye, and the occurrence of light scorching renders the fruit unfit for commercial sale. The illuminance of this result (mW / cm 2 ) was measured using a photodiode sensor (type: PD300-UV: Ophir) whose sensitivity was calibrated to the peak wavelength of the LED used. 2 ) is the illuminance (mW / cm 2 The illuminance and dose in this specification can be measured or calculated in the same manner.

[0054] These results suggest that light with a peak wavelength of 280 nm can be applied to harvested strawberries at a rate of 18 mJ / cm 2 ~54mJ / cm 2 It was found that the weight loss during storage at 15°C can be reduced by irradiating both sides with an irradiation dose of 180 mJ / cm. 2 ~414mJ / cm 2 No such effect was observed in the range

[0055] After the storage test was completed, the strawberries under conditions 1 and 3 were observed using an optical microscope, and it was found that the percentage of closed stomata was higher under condition 3 than under condition 1. Specifically, the percentage of closed stomata was 50% under condition 1, whereas the percentage of closed stomata was 76% under condition 3. Figures 2A and 2B are photographs showing the state of stomata observed under an optical microscope. Figure 2A is a photograph of the stomata in a closed state, and Figure 2B is a photograph of the stomata in an open state.

[0056] One of the mechanisms of the weight loss reduction is thought to be the reduction in water evaporation due to stomatal closure. It is thought that the UV response of UVR8 photoreceptors, which have an absorption peak at 280 nm, is involved in the promotion of stomatal closure by irradiation with light with a peak wavelength of 280 nm.

[0057] (Experiment 2) Next, experiment 2 was conducted, in which the irradiation conditions were changed from experiment 1. The changes from experiment 1 were that one-sided irradiation was performed by turning on only the upper LED without turning on the lower LED, and that the irradiation amount and illuminance were changed accordingly, as shown in Table 2. Apart from that, the same equipment was used as in experiment 1, and the freshness-maintaining effect was confirmed under the same conditions. The storage method and weight measurement method were also the same as in experiment 1.

[0058] [Table 2]

[0059] The results are shown in Figure 3. Under conditions 3 to 5, weight loss was significantly reduced compared to condition 1. Calculation of the number of days for 95% weight retention, an index of freshness, showed that while it was 3 days under condition 1, it was extended to 4.4 to 6 days under conditions 3 to 5. In other words, conditions 3 to 5 showed approximately 1.5 to 2 times the freshness retention effect compared to condition 1. On the other hand, conditions 2 and 6 did not show any significant advantages over condition 1.

[0060] From these results, it was found that after harvesting, strawberries were exposed to light with a peak wavelength of 280 nm at 5 mJ / cm 2 ~50mJ / cm 2 It was found that the weight loss during storage at 15°C can be reduced by irradiating one side with an irradiation dose of 1 mJ / cm. 2 and 100mJ / cm 2 In this case, no such effect was observed.

[0061] From the results of Experiments 1 and 2, the optimal irradiation dose when using light with a peak wavelength of 280 nm is 5 mJ / cm 2 ~54mJ / cm 2 It turns out it was nearby.

[0062] (Experiment 3) Next, in order to investigate the effect of irradiation time, experiment 3 was carried out with a fixed irradiation amount. The changes from experiment 2 were that the irradiation amount and illuminance were changed as shown in Table 3. In addition, the number of strawberries placed in one food pack was changed to 15. Other than that, the freshness-maintaining effect was confirmed under the same conditions as experiment 2.

[0063] [Table 3]

[0064] The results are shown in Figure 4. Under conditions 2 to 4, weight loss was significantly reduced compared to condition 1. Calculation of the number of days for 95% weight retention, an index of freshness, showed that while condition 1 was 1.6 days, conditions 2 to 4 extended this to approximately 2 days. In other words, conditions 2 to 4 showed approximately 1.25 times the freshness retention effect compared to condition 1. On the other hand, condition 5 did not show any significant advantage over condition 1.

[0065] These results show that even with the same single-sided irradiation and the same amount of irradiation, the effect of maintaining freshness decreases as the irradiation time increases. It was found that weight loss during storage at 15°C can be reduced by irradiating one side of harvested strawberries with light with a peak wavelength of 280 nm for less than 180 seconds, preferably 18 seconds or less. It is thought that if the irradiation time is too long, it may damage the skin through the accumulation of active oxygen species, which may impair the skin's moisturizing effect.

[0066] The reason why the number of days to maintain 95% weight in condition 1 was shorter than in experiments 1 and 2 is thought to be because experiment 3 was conducted in the later stages of strawberry harvest, which caused the skin to soften and resulted in a large amount of water evaporating from the skin.

[0067] (Experiment 4) In order to confirm whether there are differences in freshness-maintaining effects depending on the strawberry variety, Kaorino, a seasonal strawberry harvested in winter and spring, was used, unlike in Experiments 1 to 3. As with Experiment 2, the same equipment as in Experiment 1 was used for LED irradiation, and one-sided irradiation was performed by turning on only the upper LED without turning on the lower LED. The irradiation conditions are as shown in Table 4.

[0068] [Table 4]

[0069] After the light irradiation, 10 strawberries for each irradiation condition were placed in the same food packs as in Experiment 1 and stored in a thermostatic chamber at 10°C. The relative humidity was about 45%. The weight measurement method was the same as in Experiment 1.

[0070] The results are shown in Figure 5. All of conditions 2 to 4 were able to reduce weight loss compared to condition 1. Calculating the number of days for which 95% weight was maintained, an index of freshness, showed that while condition 1 was 5 days, conditions 2 to 4 extended this to 6.4 to 7 days. In other words, conditions 2 to 4 showed a freshness maintenance effect that was approximately 1.3 to 1.4 times greater than condition 1.

[0071] From these results, it was found that the effect was reproduced with roughly the same amount of irradiation even if the variety was different, but there were some differences in the amount of irradiation depending on the variety. In experiment 4 using Kaorino, the effect was not observed in experiment 2 using Pechika Honoka, with an irradiation of 100 mJ / cm 2 Even so, the effect of maintaining freshness is obtained.

[0072] Using the samples from Experiment 4, after the storage test was completed, the peel hardness was measured and the components were analyzed. . (hardness measurement) For the hardness measurement, we used a digital simple push-pull gauge S9500 series and an electric stand MODEL-2257 manufactured by Aiko Engineering Co., Ltd. The tip was cylindrical (diameter Φ2 mm) and the pressing speed was 60 mm / min.

[0073] The results of measuring the skin hardness are shown in Figure 6. The graph shows the average value and standard deviation for 10 pieces each. For reference, the data on the day of harvest is shown. While condition 1 was the reference, that is, the skin hardness tended to be lower than that on the day of harvest, conditions 2 to 4 tended to maintain the skin hardness. In particular, condition 3 (irradiation dose 50 mJ / cm 2 ) was also found to have a significant difference by t-test.

[0074] One of the mechanisms by which skin firmness is maintained is thought to be that intracellular nitric oxide produced in response to ultraviolet light by the UVR8 photoreceptor acts as a signal to suppress the activity of skin-degrading enzymes, thereby reducing water evaporation.

[0075] It is also believed that the inactivation of the function of the peel decomposition enzyme is due to the fact that amino acids (especially tyrosine and tryptophan) that form cell wall decomposition enzymes and pectin decomposition enzymes that soften the peel have an absorption peak at 280 nm. It is believed that these amino acids may have been denatured by irradiating light with a peak wavelength of 280 nm, deactivating the function of the peel decomposition enzymes. This is thought to be unrelated to UVR8, but it is known that the tissues of fruits and vegetables universally contain cell wall decomposition enzymes and pectin decomposition enzymes, regardless of plant species, which soften the peel, epidermis, and entire tissues and are involved in the deterioration of freshness due to moisture evaporation. Therefore, it is thought that this effect also applies in principle not only to strawberries but also to all post-harvest fruits and vegetables.

[0076] (Antioxidant measurement) Antioxidative activity was measured by the DPPH radical scavenging activity measurement method. The measurement sample was extracted with an ethanol aqueous solution and the supernatant was used. The results were expressed as DPPH radical scavenging activity values ​​and calculated in Trolox equivalents.

[0077] The results of the antioxidant activity measurement are shown in Figure 7. Condition 2 (10 mJ / cm 2 ) and condition 3 (50 mJ / cm 2 ) It was confirmed that the antioxidant properties of both conditions were greater than those of condition 1.

[0078] (Fisetin content measurement) The fisetin content was measured using liquid chromatography-mass spectrometry (quadrupole type). The sample was extracted with an aqueous ethanol solution, and the supernatant was used. The column used was an ACQUITY UPLC HSS T3 (2.1 mm x 100 mm), with a column temperature of 40°C, a mobile phase of 50 mM ammonium formate aqueous solution containing 0.1% formic acid and methanol, and a flow rate of 0.3 mL / min. The mass spectrometry conditions were ESI Negative mode, SIR (precursor ion m / z 284.9).

[0079] The fisetin content measurement results are shown in Figure 8. Condition 1 was below the detection limit of the analytical device, but condition 2 (10 mJ / cm 2 ) and condition 3 (50 mJ / cm 2) increased significantly.

[0080] (Nitrate nitrogen concentration measurement) The nitrate nitrogen concentration was measured using the NO2 / NO3 Assay Kit-CII (Colorimetric) - Griess Reagent Kit - (Dojindo Chemical Industries, Ltd.). The measurement samples were treated according to the instructions for the kit.

[0081] The results of the nitrate nitrogen concentration measurement are shown in Figure 9. 2 ) was found to have decreased by approximately 60% compared to condition 1.

[0082] (Consideration of measurement results) From the above measurement results, it can be seen that antioxidant properties and fisetin, which are beneficial health components, increased in Experiment 4. Regarding antioxidant properties, the intake of fruits and vegetables with high antioxidant properties is recommended in order to remove the increased active oxygen in the human body and suppress aging and lifestyle-related diseases. In addition, fisetin is known to have many physiologically active effects, such as antitumor, antioxidant, anti-inflammatory, anti-angiogenic, hyperlipidemia, and neuroprotection.

[0083] Also, in experiment 4, it can be seen that the concentration of nitrate nitrogen decreases. Nitrate nitrogen itself is not harmful to humans at normal intake levels. However, when nitrate nitrogen is reduced in the body and converted into nitrite ions, it is said that there is a possibility that it may cause methemoglobinemia, a type of respiratory inhibition, or convert into nitroso compounds, which are carcinogenic substances.

[0084] Therefore, the increase in antioxidant activity and fisetin, and the decrease in nitrate nitrogen concentration are favorable for human health. The mechanism of these effects is thought to be the ultraviolet response of the UVR8 photoreceptor, which has an absorption peak at 280 nm.

[0085] (Experiment 5) In order to confirm whether there is a difference in the freshness-maintaining effect depending on wavelengths other than 280 nm, an experiment was conducted in which the wavelength was changed. The strawberries used were Kaorino, a seasonal strawberry harvested in winter and spring. As in experiment 2, the same equipment as in experiment 1 was used for LED irradiation, and one-sided irradiation was performed by turning on only the upper LED and not turning on the lower LED. The irradiation conditions are as shown in Table 4.

[0086] [Table 5]

[0087] The 254 nm lamp used was Cosmo Bio Co., Ltd. / Model No. 3116 0065 1. After the light irradiation, 10 strawberries for each irradiation condition were placed in the same food packs as in Experiment 1 and stored in a thermostatic chamber at 10°C. The relative humidity was about 45%. The weight measurement method was the same as in Experiment 1. The wavelength was measured by measuring the emission spectrum using a multichannel detector (model: PMA-11C7473: Hamamatsu Photonics). The wavelength in this specification can be measured in the same manner.

[0088] The results are shown in Figure 11. No effect of reducing weight loss was observed under any of conditions 2 to 5. From these results, it was found that the 254 nm lamp and 310 nm LED had no effect on maintaining freshness.

[0089] (Experiment 6) Strawberries that had been harvested for about two hours were irradiated with LED light with a peak wavelength of 270 nm. A Berry Pop Tin was used for the strawberries. As in Experiment 2, the same equipment as in Experiment 1 was used for LED irradiation, and one-sided irradiation was performed by turning on only the upper LED and not turning on the lower LED. The irradiation conditions are shown in Table 6.

[0090] [Table 6]

[0091] After light irradiation, 13 strawberries for each irradiation condition were placed in the same food packs as in Experiment 1 and stored in a thermostatic chamber at 6°C. The relative humidity was approximately 76%. Weights were measured before storage (i.e., 0 days of storage) and after 7 days of storage. The weight measurement method was the same as in Experiment 1.

[0092] The results are shown in Figure 12. Under condition 2, weight loss was significantly reduced compared to condition 1. When the number of days to maintain weight at which the weight change rate reached 98% was calculated, it was 4.7 days under condition 1 and 6.2 days under condition 2. In other words, condition 2 showed a freshness maintenance effect that was 1.32 times that of condition 1. Therefore, the number of days to maintain 95% weight, which is an index of freshness, can be expected to be extended by approximately 1.3 times.

[0093] These results demonstrate that 270 nm light has the same freshness-maintaining effect as 280 nm light.

[0094] The mechanism for maintaining freshness is thought to involve the UVR8 photoreceptor, just as with 280 nm, and therefore it is believed to be effective in the wavelength range of 256 to 400 nm, which is the main wavelength range detected by the UVR8 photoreceptor, with an even greater effect in the range of 256 to 297 nm, and an even more notable effect in the range of 265 to 297 nm.

[0095] (Experiment 7) Three cucumbers that had been harvested for about six hours were irradiated with LED light with a peak wavelength of 280 nm. As in experiment 2, the same equipment as in experiment 1 was used for LED irradiation, and one-sided irradiation was performed by turning on only the upper LED and not turning on the lower LED. The irradiation conditions are shown in Table 7.

[0096] [Table 7]

[0097] After light irradiation, the cucumbers were placed in polystyrene foam storage trays according to the irradiation conditions and stored in a thermostatic chamber at 23°C. The relative humidity was approximately 40%. Weights were measured before storage (i.e., 0 days of storage) and after 1 and 2 days of storage. The weights were measured together for three cucumbers taken out of the storage tray.

[0098] The results are shown in Figure 13. Under condition 2, weight loss was significantly reduced compared to condition 1. When the number of days for weight retention at which the weight change rate reached 95% was calculated, it was 1 day under condition 1, whereas it was 1.27 days under condition 2. In other words, condition 2 showed a freshness retention effect that was 1.27 times greater than that of condition 1.

[0099] These results show that irradiating cucumbers with 280 nm light has the same effect on maintaining their freshness as strawberries. The mechanism of freshness maintenance is thought to involve the UVR8 photoreceptor, just like in strawberries.

[0100] (Experiment 8) A single broccoli head that had been harvested for approximately six hours was irradiated with LED light with a peak wavelength of 280 nm. As in experiment 2, the same equipment as in experiment 1 was used for LED irradiation, and one-sided irradiation was performed by turning on only the upper LED and not turning on the lower LED. The irradiation conditions are shown in Table 8.

[0101] [Table 8]

[0102] After light irradiation, the broccoli were placed in polystyrene foam storage trays according to the irradiation conditions and stored in a thermostatic chamber at 23°C. The relative humidity was approximately 40%. Weight measurements were taken before storage (i.e., 0 days of storage) and two days after the start of storage. Weight measurements were taken of one broccoli taken out of the storage tray.

[0103] The results are shown in Figure 14. Under condition 2, weight loss was significantly reduced compared to condition 1. When the number of days for weight retention at which the weight change rate reached 95% was calculated, it was 0.61 days under condition 1, while it was 0.77 days under condition 2. In other words, condition 2 was 1.26 times more effective at maintaining freshness than condition 1. Furthermore, visual observation showed that yellowing of flower buds was reduced under condition 2 compared to condition 1 after 2 days of storage.

[0104] These results show that 280 nm light irradiation can help maintain the freshness of broccoli, just as it does for strawberries. The mechanism of freshness maintenance is thought to involve the UVR8 photoreceptor, just like for strawberries.

[0105] (Experiment 9) The strawberries were placed in a light-transmitting container and irradiated with LED light. An experiment was conducted in which strawberries were stored in storage materials. A berry pop tin was used for the strawberries. Approximately two hours after harvest, LED light with a peak wavelength of 280 nm was irradiated through a translucent container onto the strawberries. As in experiment 2, the same equipment as in experiment 1 was used for LED irradiation, and one-sided irradiation was performed by turning on only the upper LED and not turning on the lower LED. The irradiation conditions are as shown in Table 9.

[0106] [Table 9]

[0107] The light-transmitting container was a food pack, and the amount of irradiation and illuminance were the values ​​that actually hit strawberries. 15 strawberries were placed in each food pack, 5 pieces per pack, for each irradiation condition. The food pack was made of polystyrene resin, and the lid of the food pack was closed, but not airtight, allowing air to enter and exit.

[0108] After light irradiation, each food pack was placed in P-Plus (registered trademark, manufactured by Sumitomo Bakelite), an MA packaging material, and stored in a constant temperature bath at 23°C. Weight measurements were taken before storage (i.e., 0 days of storage) and after 7 days of storage. Weight measurements were taken by removing the food pack from the P-Plus (registered trademark), measuring each food pack together, and then adding up the weights. The weight of the food pack, which had been measured previously, was subtracted from the measured weight to calculate the weight of the 15 strawberries.

[0109] The results are shown in Figure 15. Under condition 2, weight loss was significantly reduced compared to condition 1. The number of days for weight retention at which the weight change rate reached 99% was calculated to be 2.5 days under condition 1 and 4.1 days under condition 2. In other words, condition 2 showed a freshness retention effect that was 1.64 times greater than that of condition 1. Therefore, the number of days for 95% weight retention, which is an index of freshness, can be expected to be extended by approximately 1.6 times. Visual observation showed that mold generation was reduced under condition 2 compared to condition 1 after 7 days of storage. The mold generation rate was 87% under upper limit 1, but decreased to 40% under condition 2.

[0110] These results show that exposure to 280 nm light and packaging in MA packaging materials helps maintain freshness, and in particular reduces the growth of mold.

[0111] It is believed that the reduction in mold growth is due to the sterilization of mold and the improvement of plant immunity. The main factor in the mold sterilization effect is the generation of CPD (cyclobutane pyrimidine dimer) and 6-4PP (6-4 type photoproduct), which indicate DNA damage in mold. It is believed that the most notable effect is in the wavelength range of 256 nm to 297 nm, which is absorbed by DNA. In addition, the plant immunity-improving effect is thought to be a systemically acquired anti-fungal effect that occurs when the UVR8 photoreceptor receives LED light and secretes salicylic acid and other substances throughout the body. This is supported by the fact that the mold growth reduction effect was observed even on the back side of the strawberry, i.e., the side not exposed to LED light. Therefore, it is thought to be effective in the wavelength range of 256nm to 400nm, which is the main range detected by the UVR8 photoreceptor, and is even more effective in the range of 256nm to 297nm, and even more pronounced in the range of 265nm to 297nm. Since mold often grows on damaged areas of fresh produce such as strawberries, it is suggested that shining LED light on damaged areas would be more effective.

[0112] It is preferable to irradiate the translucent container with light before placing it in the MA packaging material, as this improves workability. By irradiating the container with light, it is possible to prevent damage to the fruits and vegetables during handling.

[0113] (Experiment 10) To investigate the effects of light after irradiation, an experiment was conducted to confirm whether there was any difference in the freshness-maintaining effect by storing the strawberries for a certain period of time under indoor lighting after irradiation with 280 nm LED light. A Berry Pop tin was used for the strawberries. Strawberries that had been harvested for approximately two hours were irradiated with LED light with a peak wavelength of 280 nm. As with experiment 2, the same equipment as in experiment 1 was used for LED irradiation, and one-sided irradiation was performed by turning on only the upper LED and not turning on the lower LED. The irradiation conditions are as shown in Table 10.

[0114] [Table 10]

[0115] After the light irradiation, eight strawberries for each irradiation condition were placed in the same food packs as in Experiment 1 and incubated at approximately 20 μmol / m 2The specimens were stored for 1 hour under room lighting at 3500 s and in a cardboard box away from room lighting, and then stored in a thermostatic chamber at 6°C. The relative humidity was approximately 76%. Weights were measured before storage (i.e., on day 0 of storage) and after 5 and 10 days of storage. The weight measurement method was the same as in Experiment 1.

[0116] The results are shown in Figure 16. Under conditions 2 and 3, weight loss was significantly reduced compared to condition 1. When the number of days for 95% weight retention, an index of freshness, was calculated, it was 4 days under condition 1, 5 days under condition 2, and 6.4 days under condition 3. In other words, compared to condition 1, condition 2 showed a 1.25-fold increase in freshness retention effect, and condition 3 showed a 1.6-fold increase in freshness retention effect.

[0117] From these results, it became clear through experimental examples that weight loss during storage at 6°C can be further reduced by irradiating strawberries with 280 nm light and then blocking indoor lighting after the light irradiation. This is thought to be because the blue light contained in indoor lighting acts on stomatal opening, suppressing the effect of reducing water evaporation.

[0118] Through the contents described so far in this specification, the following technical matters are disclosed. (Section 1) A method for maintaining the freshness of fruits and vegetables, comprising irradiating fruits and vegetables within 24 hours after harvest with light having a peak wavelength in the range of 256 nm or more and 297 nm or less, thereby extending by 25% or more the time during which the fruits and vegetables maintain at least 95% of their weight before exposure to said light. (Section 2) The integrated light quantity of the light is 5 mJ / cm 2 More than 100mJ / cm 2 Item 1. A method for maintaining the freshness of fruits and vegetables, comprising: (Section 3) The integrated light quantity of the light is 5 mJ / cm 2 More than 60mJ / cm 2 Item 3. A method for maintaining the freshness of fruits and vegetables according to item 1 or 2, which is as follows: (Section 4) Item 4. The method for preserving the freshness of fruits and vegetables according to any one of Items 1 to 3, wherein the light is irradiated to the fruits and vegetables while the fruits and vegetables are placed on a mounting member having a mounting surface with an average light reflectance of 20% or more. (Section 5) Item 5. The method for preserving the freshness of fruits and vegetables according to any one of items 1 to 4, wherein the light is irradiated onto the fruits and vegetables in a state where the fruits and vegetables are placed in a light-transmitting container. (Section 6) Item 6. The method for preserving the freshness of fruits and vegetables according to any one of Items 1 to 5, wherein the fruits and vegetables are strawberries. (Section 7) Item 7. The method for maintaining the freshness of fruits and vegetables according to Item 6, wherein the fisetin content of the strawberries after the light irradiation is greater than the fisetin content of the strawberries before the light irradiation. (Section 8) Item 7. The method for maintaining the freshness of fruits and vegetables according to Item 6, wherein the DPPH radical scavenging activity value of the strawberry after the light irradiation is higher than the DPPH radical scavenging activity value of the strawberry before the light irradiation. (Section 9) Item 7. The method for maintaining the freshness of fruits and vegetables according to Item 6, wherein the nitrate nitrogen concentration of the strawberries after the light irradiation is lower than the nitrate nitrogen concentration of the strawberries before the light irradiation. [Explanation of symbols]

[0119] 100 Light irradiation device 10 LED Module 12 LED 14 LED mounting board 16 Heat sink 20 Fruits and vegetables 30 LED power supply 40 Sequencer 50 Fans 60 Major 70 Tray 72 Placement surface 80 Jack 90 Stages

Claims

1. A method for maintaining the freshness of fruits and vegetables, comprising irradiating fruits and vegetables within 24 hours after harvest with light having a peak wavelength in the range of 256 nm or more and 297 nm or less, thereby extending by 25% or more the time during which the fruits and vegetables maintain at least 95% of their weight before exposure to the light.

2. The integrated light amount of the light is 5 mJ / cm ２ More than 100mJ / cm ２ Below is the The method for maintaining the freshness of fruits and vegetables according to claim 1.

3. The integrated light amount of the light is 5 mJ / cm ２ More than 60mJ / cm ２ Below is the The method for maintaining the freshness of fruits and vegetables according to claim 1.

4. 2. The method for maintaining the freshness of fruits and vegetables according to claim 1, wherein the light is irradiated to the fruits and vegetables while the fruits and vegetables are placed on a mounting member having a mounting surface with an average light reflectance of 20% or more.

5. The method for maintaining freshness of fruits and vegetables according to claim 1 , wherein the light is irradiated onto the fruits and vegetables in a state where the fruits and vegetables are placed in a light-transmitting container.

6. 2. The method for preserving the freshness of fruits and vegetables according to claim 1, wherein the fruits and vegetables are strawberries.

7. 7. The method for maintaining the freshness of fruits and vegetables according to claim 6, wherein a fisetin content in the strawberries after the light irradiation is greater than a fisetin content in the strawberries before the light irradiation.

8. 7. The method for maintaining the freshness of fruits and vegetables according to claim 6, wherein the DPPH radical scavenging activity value of the strawberries after the irradiation with light is increased compared to the DPPH radical scavenging activity value of the strawberries before the irradiation with light.

9. 7. The method for maintaining the freshness of fruits and vegetables according to claim 6, wherein the nitrate nitrogen concentration in the strawberries after the irradiation with light is lower than the nitrate nitrogen concentration in the strawberries before the irradiation with light.

10. A freshness preservation system owned by a user who processes fruits and vegetables cultivated by a grower in a cultivation space to manufacture and sell processed foods, A collection space for collecting the fruits and vegetables; an irradiation space having a light irradiation device that performs the freshness preservation method according to any one of claims 1 to 9, and in which the freshness preservation method is performed on the collected fruits and vegetables; A storage space for storing the fruits and vegetables for which the freshness preservation method has been performed; A freshness preservation system comprising: a processed food production space for producing processed foods using the fruits and vegetables stored in the storage space.

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