Method for suppressing coloration of white asparagus and coloration suppression facility

Abstract

To provide a coloration suppression method and a coloration suppression facility that are capable of suppressing coloration of white asparagus even under an environment exposed to light.SOLUTION: A coloration suppression method includes a first irradiation step of irradiating white asparagus during cultivation or after harvesting with far-red light and light in a wavelength region other than far-red light, and a second irradiation step of irradiating the white asparagus with far-red light alone. The light in the wavelength region other than far-red light is irradiated during work by a worker handling the white asparagus, and the far-red light may be irradiated constantly or intermittently.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and equipment for inhibiting discoloration of white asparagus. [Background technology]

[0002] Growing health preferences and a shift to Westernized food have led to the cultivation of white asparagus in Japan. It is known that white asparagus produces chlorophyll and anthocyanins when exposed to light during cultivation, causing rapid coloring. To prevent this coloring, cultivation involves hilling up soil or using shading film. For example, Patent Document 1 discloses a method for cultivating white asparagus in a field by covering a framework with shading film to block out light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-179417 Summary of the Invention [Problem to be solved by the invention]

[0004] The method of Patent Document 1 is designed to block light from reaching the white asparagus during cultivation, which inevitably means that harvesting and shipping work must also be done in the dark, without lighting, resulting in problems such as poor work efficiency and a heavy burden on workers. Furthermore, even if efforts are made to block light during harvesting and shipping, the asparagus is exposed to sunlight and indoor lighting when sold in stores, making it difficult to maintain its quality over long periods of time.

[0005] The present invention has been made based on this background, and aims to provide a discoloration suppression method and discoloration suppression equipment that can suppress discoloration of white asparagus even in an environment where it is exposed to light. [Means for solving the problem]

[0006] In order to achieve the above object, the coloring suppression method according to the present invention comprises the steps of: A first irradiation step of irradiating white asparagus during cultivation or after harvest with far-red light and light in a wavelength range other than far-red light; a second irradiation step of irradiating the white asparagus with far-red light alone; Includes. [Effects of the Invention]

[0007] According to the present invention, a discoloration suppression method and discoloration suppression equipment can be provided that can suppress discoloration of white asparagus even in an environment where it is exposed to light. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a graph showing the flow of a coloration suppression method according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing the configuration of a greenhouse in which a coloration suppression light source according to an embodiment of the present invention is installed; [Figure 3] 1 is a diagram showing a configuration of a coloration suppression light source according to an embodiment of the present invention; [Figure 4] Graphs (a) and (b) show the differences in the L*, a*, and b* values ​​of white asparagus measured in the illuminated and dark areas in Example 1, with the target periods being May and June, respectively. [Figure 5] 1 is a graph showing changes in outside air temperature in the farm field used in Example 1. [Figure 6] 1 is a graph showing the differences in L* value, a* value, and b* value of white asparagus measured in an irradiated area and a dark area in Example 2. [Figure 7] Graphs (a) to (c) show the L* value, a* value, and b* value of post-harvest white asparagus measured in Example 3. [Figure 8] Graphs (a) to (c) show the L* value, a* value, and b* value of post-harvest white asparagus measured in Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a method and apparatus for inhibiting discoloration of white asparagus according to an embodiment of the present invention will be described in detail with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals.

[0010] The discoloration suppression method according to the embodiment is a method for suppressing discoloration of white asparagus even in an environment where light is present, and is applicable, for example, to the cultivation, harvesting, storage, shipping, and retail sales of white asparagus. By using the discoloration suppression method according to the embodiment, white asparagus, which is prone to discoloration due to light, can be handled in a bright environment, improving the work environment and work efficiency. Furthermore, because discoloration is suppressed even when the asparagus is displayed for long periods of time for retail sales, it is possible to maintain quality over long periods of time and improve yields.

[0011] As shown in FIG. 1 , the discoloration suppression method according to the embodiment includes a first irradiation step of irradiating white light and far-red light, and a second irradiation step of irradiating far-red light alone. White light is a mixture of light of various wavelengths in the visible light range, and does not give humans the sense of color. Visible light is light with wavelengths visible to the human eye, approximately in the wavelength range of 400 nm to 700 nm. Far-red light, unlike red light, is light that is difficult or almost invisible to the human eye, and is light with a wavelength range of 700 nm to 800 nm. As a result of extensive research, the inventors have found that discoloration of white asparagus caused by visible light can be suppressed by irradiating far-red light onto white asparagus using the discoloration suppression method according to the embodiment.

[0012] The first irradiation step is performed for a shorter period than the second irradiation step and is set during the time period when workers handle the white asparagus. The first irradiation step and the second irradiation step are preferably performed consecutively without any interval, but may be performed with an interval between them. Furthermore, the first irradiation step and the second irradiation step may be performed only once in sequence, or may be performed repeatedly in the same order.

[0013] The process consisting of the first irradiation step and the second irradiation step is preferably repeated daily. The irradiation time of the white light is preferably as short as possible within the range that allows for manual operation, in order to avoid discoloration of the white asparagus. White light is preferably irradiated for, for example, 5 minutes to 3 hours per day, preferably 30 minutes to 2 hours per day, for example, 1 hour per day. On the other hand, far-red light may be irradiated continuously or intermittently. For intermittent irradiation, irradiation may be temporarily stopped, for example, during the night. The time for which far-red light irradiation is stopped is, for example, 1 hour to 3 hours per day. In particular, when handling white asparagus after harvest, the irradiation time of far-red light is preferably at least three times the irradiation time of white light and far-red light.

[0014] In order to avoid discoloration of the white asparagus, it is preferable to keep the irradiance of the white light as low as possible within the range that allows workers to work with it. The irradiance of the white light is preferably set so that the illuminance of the white asparagus cultivation surface is within the range of 300 lux to 800 lux. On the other hand, the irradiance of the far-infrared light is preferably equal to or lower than the irradiance of the white light, and more preferably within the range of 1 to 1 / 5 times the irradiance of the white light. As an example, if a light source is to be installed on the ceiling of a greenhouse large enough for a person to stand and walk in, the irradiance of the white light should be 1.9 W / m 2 , the irradiance of far-red light is 1.5W / m 2 Just set it to

[0015] The discoloration suppression method according to the embodiment uses a discoloration suppression light source 1 that is installed in a building where white asparagus is handled and that can brightly illuminate the interior of the building. The building need only have a roof and pillars, and does not necessarily have to have walls, be fixed to the ground, or be durable. Examples of such buildings include greenhouses, storage facilities, workshops, collection points, and sales stores. Below, with reference to FIG. 2, an example of using the discoloration suppression light source 1 in a greenhouse H will be described.

[0016] The greenhouse H comprises a framework F installed on the ground GL and a shading film B that is installed to cover the framework F and is capable of blocking light. Inside the greenhouse H, a discoloration suppression light source 1 supported by the framework F is installed. The discoloration suppression light source 1 is, for example, a straight tube-shaped light source that extends linearly. The discoloration suppression light source 1 extends, for example, in the longitudinal direction of the greenhouse H and is installed above the white asparagus W so that light is irradiated onto the white asparagus W being cultivated.

[0017] Next, the configuration of a coloration-suppressing light source 1 according to an embodiment will be described with reference to Fig. 3. The coloration-suppressing light source 1 includes a white light source 2 that emits white light and a far-red light source 3 that emits far-red light. The white light source 2 is an example of a first light source, and the far-red light source 3 is an example of a second light source. The white light source 2 and the far-red light source 3 are alternately arranged in a straight line inside a light-transmitting housing 4. The white light source 2 and the far-red light source 3 are, for example, bulb-shaped LED (Light Emitting Diode) light sources.

[0018] A far-red LED light source is, for example, an LED light source with a sharp peak around 760 nm. White LED light sources include, for example, a white LED light source with a blue LED chip coated with yellow phosphor, a white LED light source combining red, green, and blue LED chips, and a white LED light source with a blue LED chip coated with red and green phosphors.

[0019] Although each white LED light source has a different light spectrum, they all contain light in the same wavelength range, so any white LED light source can be used. However, considering acquisition costs, it is preferable to use a white LED light source with a blue LED chip coated with yellow phosphor. This white LED light source has a sharp peak around a wavelength of 450 nm and a gentle peak around a wavelength of 570 nm. The sharp peak around 450 nm comes from the blue LED chip, and the gentle peak around 570 nm comes from the yellow phosphor.

[0020] The coloration suppression light source 1 includes a user-operable operation switch for individually turning on and off the white light source 2 and the far-red light source 3. The user can operate the white light source 2 at a preset timing to cause the coloration suppression light source 1 to perform a first irradiation step and then a second irradiation step. The coloration suppression light source 1 may be powered by an external power source or may include an internal battery capable of supplying power. The above is the configuration of the coloration suppression light source 1.

[0021] As described above, the discoloration suppression method according to the embodiment includes a first irradiation step of irradiating white asparagus during cultivation or after harvest with far-red light and light in a wavelength range other than far-red light, and a second irradiation step of irradiating white asparagus with far-red light alone. Irradiating white asparagus with far-red light can suppress discoloration of white asparagus caused by light in wavelength ranges other than far-red light, so discoloration of white asparagus can be suppressed even in an environment where it is exposed to light in wavelength ranges other than far-red light.

[0022] The present invention is not limited to the above-described embodiment, and the following modifications are possible.

[0023] (Variation) In the above embodiment, the white light source 2 and the far-red light source 3 are housed in the same housing 4, but the present invention is not limited to this. For example, the white light source 2 and the far-red light source 3 may be housed in separate housings or may be arranged separately.

[0024] In the above embodiment, the white light sources 2 and the far-red light sources 3 are arranged alternately in a straight line, but the present invention is not limited to this. For example, the white light sources 2 and the far-red light sources 3 may be arranged on a circle, or a plurality of white light sources 2 or far-red light sources 3 may be arranged consecutively.

[0025] In the above embodiment, the white light source 2 and the far-red light source 3 are bulb-type LED light sources, but the present invention is not limited to this. For example, the white light source 2 and the far-red light source 3 may be straight-tube LED light sources. In this case, the white light source 2 and the far-red light source 3 may be arranged close to each other in the same housing, or may be arranged at a distance from each other. Furthermore, at least one of the white light source 2 and the far-red light source 3 may be a fluorescent lamp. As a fluorescent lamp that emits far-red light, for example, a fluorescent lamp in which a lithium iron aluminate phosphor is coated on the inside of a fluorescent tube may be used.

[0026] In the above embodiment, the color-suppressing light source 1 is installed on the ceiling of a building, but the present invention is not limited to this. For example, the color-suppressing light source 1 may be installed on the wall of a building or attached to the tip of a stand installed on the ground. The color-suppressing light source 1 may also be installed outside of a building, for example, on a shelf such as a display shelf or a parcel shelf, or in a storage room or refrigerated warehouse installed within a building.

[0027] In the above embodiment, the white light source 2 and the far-red light source 3 are individually turned on and off using an operation switch, but the present invention is not limited to this. For example, the discoloration suppression light source 1 may be communicably connected to a control device (not shown) that individually controls the output of the white light source 2 and the far-red light source 3, thereby configuring a discoloration suppression system that suppresses discoloration of white asparagus during cultivation. The control device includes a memory that stores a program and a processor that executes the program stored in the memory. By executing the program, the processor controls the operation of the white light source 2 and the far-red light source 3 to execute a first irradiation step and then a second irradiation step. Information regarding the start times and durations of the first irradiation step and the second irradiation step may be stored in the memory upon receiving a user's instruction.

[0028] In the above embodiment, white light is used as the light in a wavelength range other than far-red light, but the present invention is not limited to this. For example, the light in a wavelength range other than far-red light may be blue light, green light, yellow light, red light, or a mixed light containing at least one of these lights.

[0029] The above-described embodiments are merely examples, and the present invention is not limited to these. Various embodiments are possible within the scope of the invention as set forth in the claims. The components described in the embodiments and modifications can be freely combined. Furthermore, inventions equivalent to the inventions set forth in the claims are also included in the present invention. [Example]

[0030] The present invention will be specifically described below with reference to examples, although the present invention is not limited to these examples.

[0031] Example 1 In Example 1, we investigated the effect of irradiating white asparagus grown outdoors with white light and far-red light on the coloration of the white asparagus. Because white asparagus is not harvested at the same time, we also took into account the difference in coloration depending on the cultivation period.

[0032] To account for differences in color between varieties, two varieties were used for outdoor cultivation: "No. 056" (a line developed by Rakuno Gakuen University), which has a relatively short plant height, thick stems, and early germination, and "Welcome" (Sakata Seed Corporation), which is widely used in domestic production areas except Hokkaido. Seeds were sown between August and October 2020 and grown in 20L pots from 2021 to April 2022. Next, in late April 2022, white asparagus was planted in an open field using a soil nutrient ratio of 20% nitrogen, 15% phosphorus, 18.6% potassium, and 200% dolomitic lime (all units: kg / 10a). After planting, irrigation and pest control were performed as appropriate.

[0033] In the open field, two greenhouse frameworks measuring 2.7 m wide, 2.1 m high, and 9 m long were set up, each covered with shading film, with one greenhouse assigned to an irradiated area and one to a dark area (control). The shading film was White Silver (Tokan Kosan Co., Ltd.). In the irradiated area, a 120 cm long white light capable of selectively emitting far-red light was installed at a height of approximately 2 m in the center of the greenhouse. The white light was irradiated from 9:00 to 10:00 a.m. every day, corresponding to harvest time, and the far-red light was irradiated continuously.

[0034] The white light is a 120cm long straight tube (Tajiri Machinery Co., Ltd.) and is composed of two types of LED chips that emit white light and far-red light, respectively. The white LED chip has a sharp peak around 450nm and a gentle peak around 570nm, while the far-red LED chip has a sharp peak around 760nm. The illuminance of the white light at a position 50cm above the ground was adjusted to 800 lux (approximately 1.9W / m2 in terms of irradiance). 2 The illuminance of the far-infrared light was 1 lux (approximately 1.5 W / m 2 ) The illuminance of the white light was adjusted using a Light Analyzer LA-105 (Japan Medical Instruments Manufacturing Co., Ltd.). The Industrial Safety and Health Regulations stipulate that the illuminance standard for the work surface in an office where workers are constantly employed is 300 lux or more for general office work, so this provides sufficient illuminance.

[0035] White asparagus was harvested from May 9 to June 30, 2022. After harvesting, a spectrophotometer CM-700d (Konica Minolta, Inc.) with a 5 mm diameter circular attachment was placed 5 cm below the top of the harvested young stems, and each color system was measured using the L * a * b * It was quantified using the color space. * a * b * In color space, lightness is expressed as L * Chromaticity, which indicates the value, hue, and saturation, is a * value, b * Expressed as a value. *is the red direction, -a * is the green direction, b * -b is yellow direction * In order to understand the color change due to the presence or absence of irradiation, the L * value, a * value, b * The difference in values ​​was calculated. The survey scale was 60 stems per variety, and there were no replicates for the measurements of lightness and color.

[0036] The results are shown in Figure 4. The vertical axis of the graph, "irradiated area - dark area," represents the value obtained by subtracting the average value of the dark area from the average value of the coloration in the irradiated area. As shown in Figure 4(a), the L of the young stems harvested in May * value, a * value, b * On the other hand, as shown in Figure 4(b), the values ​​of the young stems harvested in June did not change significantly between the light and dark treatments or between varieties. * The values ​​changed towards yellow, and this tendency was particularly noticeable in "No. 056." According to data from the Japan Meteorological Agency shown in Figure 5, the average temperature in the field in May was 11.8°C, with a maximum temperature of 17.5°C and a minimum temperature of 6.5°C, while the average temperature in June was 17.1°C, with a maximum temperature of 22.5°C and a minimum temperature of 12.4°C. It is estimated that the room temperature inside the greenhouse, which is covered with shading film, is even higher than the outside temperature.

[0037] From the above, it can be seen that when white asparagus is grown outdoors using a shading film, irradiating it with white light and far-infrared light when the room temperature inside the greenhouse is relatively low can suppress discoloration of the white asparagus to a level equivalent to that achieved when grown in a dark place.

[0038] Example 2 In Example 2, the effect of irradiating white asparagus with white light and far-red light during forced cultivation on the coloration of the white asparagus was examined.

[0039] For forced cultivation, four varieties were used: "Taiho Wase" (Pioneer Ecoscience Co., Ltd.), "No. 056," "Suguderu 2" (Pioneer Ecoscience Co., Ltd., where the "2" is a Roman numeral), and "Welcome." Seeds were sown in October 2021, and then transplanted in May 2022 into polyethylene bags (65 cm long, 45 cm wide) filled with 20 L of medium made from an equal mixture of lightweight Pot Ace (Katakura Co-op Agri Co., Ltd.) and Tokachi Bark No. 1 (FOREX Mori Sangyo Co., Ltd.). The seeds were planted in polyethylene bags to facilitate subsequent transportation.

[0040] Next, the white asparagus planted in the polyethylene bags was cultivated in a greenhouse with the room temperature controlled at 15 to 25°C, while irrigation and pest control with pesticides were performed as appropriate. From mid-November 2022, a vinyl greenhouse with the same configuration as in Example 1 was installed in the greenhouse with the room temperature controlled at 10 to 15°C, and the white asparagus was transferred into the greenhouse together with the bags. In the greenhouse, white light was irradiated from 9 to 10 a.m. every day, and far-red light was continuously irradiated. The survey scale was 20 stems per variety, and measurements of brightness and chromaticity were repeated three times. Other conditions were the same as in Example 1.

[0041] The results are shown in Figure 6. The "irradiated area - dark area" on the vertical axis of the graph represents the value obtained by subtracting the average value of the dark area from the average coloration value of the irradiated area, as in Figure 4. The vertical bars on the graph represent the standard error (n=3). "NS" on the graph indicates no significant difference by t-test, and "**" indicates a significant difference at the 1% level.

[0042] Young stem L * There was no difference in the values ​​between the irradiated and dark areas or between varieties, but the L * The value has decreased. * There was no difference in the values ​​between the irradiated and dark areas, but there was a significant difference between the varieties. * The red coloring is due to the expression of anthocyanin pigments. *There were some changes in the values ​​between the illuminated and dark areas, which is thought to be due to the effects of white light and far-red light, but no significant differences were observed between varieties. Because the cultivation took place during the winter when the room temperature was low, the expression of anthocyanin pigments was promoted in some varieties. * Although the value increased, the b * It is believed that there was no difference in the values.

[0043] In Example 2, multiple comparisons were performed using a Tukey test (at a 1% level), and for cultivars that showed significant differences in mean values, letters were used in Figure 6 to indicate which groups showed significant differences. Sugdel 2, which had the largest mean value on the blue side, was marked with an a, and Wellcome, which had no significant difference from Sugdel 2, had the second largest mean value on the blue side, so it was marked ab by adding a b to the a. No. 056, which had no significant difference from Wellcome, had the third largest mean value on the blue side, so it was marked bc by adding a c to the b. There was a significant difference between Wellcome and Taiho Wase, so it was marked c alone. There were significant differences between different letters, specifically between the three groups: a and c, a and bc, and ab and c.

[0044] From the above, it can be seen that even in forced cultivation using shading film, irradiating white light and far-infrared light can suppress discoloration of white asparagus more than simply exposing it to sunlight, and in particular, by cultivating white asparagus varieties that express less anthocyanin pigments while maintaining room temperature in a greenhouse, discoloration of the white asparagus can be suppressed to a level equivalent to that achieved when grown in a dark place.

[0045] Example 3 In Example 3, the effects of irradiating harvested white asparagus with white light and far-red light on the coloration of the white asparagus were examined.

[0046] The test materials used were young "Welcome" white asparagus stems, 24 cm long and weighing 30–35 g, harvested in the early morning of June 30, 2022. First, the test materials were stored in a dark place at 5°C after harvest. On July 2, they were placed upright in a basin filled with tap water so that they could be irrigated through the cut end. Next, the test materials were placed in the first artificial climate chamber, where white light and far-red light were irradiated directly from the side. The irradiation times were 0, 1, 3, and 5 hours, respectively. Next, the test materials were placed in the second artificial climate chamber, where far-red light was irradiated directly from the side. The irradiation times were 0, 3, 9, and 15 hours, three times longer than the previous irradiation time. All test materials were placed 20 cm away from the light source in the artificial climate chamber. Each artificial climate chamber was an LH-411S (Japan Medical Instruments Manufacturing Co., Ltd.), and the room temperature was set to 25°C.

[0047] Next, the test material was stored in a dark place at room temperature of 25°C for 24 hours. The color space chromaticity was measured four times: immediately before the test, after the end of irradiation with white light and far-red light, after the end of irradiation with far-red light, and after storage in a dark place, under the same conditions as in Example 1. The illuminance of the white light near the hand (near the work surface) was adjusted to 800 lux (approximately 1.9 W / m in irradiance). 2 The illuminance of far-infrared light was 5 lux (approximately 10 W / m 2 The survey scale was 10 stems per variety, with no replication for measurements of brightness and color.

[0048] The results are shown in Figure 7. The vertical bars in the graph indicate the standard deviation (n=10). As shown in Figure 7(a), * As shown in Figure 7(b), there was no difference in the values ​​depending on the irradiation time of white light and far-red light. * The values ​​did not differ depending on the irradiation time of white light or far-red light, but they decreased slightly with each irradiation time. * There was no difference in the values ​​depending on the irradiation time of white light or far-red light, but there was a tendency for the values ​​to increase slightly over time regardless of the irradiation time.

[0049] From the above, it can be understood that if the irradiation time of harvested white asparagus with far-red light is approximately three times the irradiation time of white light and far-red light, the effect of irradiation with white light on the coloration of white asparagus is minimal.

[0050] Example 4 In Example 4, white light was irradiated for one hour every day, and far-red light was irradiated constantly to examine the effect of irradiation of white light and far-red light on the coloration of harvested white asparagus. Other conditions were the same as in Example 3. The survey scale was 10 stalks per variety, and measurements of brightness and chromaticity were repeated three times.

[0051] The results are shown in Figure 8. The vertical bars in the graph indicate the standard error (n=3). Also, "NS" in the graph means that there is no significant difference by t-test, "*" means that there is a significant difference at the 5% level, and "**" means that there is a significant difference at the 1% level. As shown in Figure 8(a), * As shown in Figure 8(b), there was no difference in the values ​​whether or not white light or far-red light was irradiated. * In both the irradiated and dark areas, the values ​​became lower one day after the start of the test than immediately after the start of the test, and thereafter remained unchanged. * There was no difference in the values ​​regardless of whether white light or far-red light was irradiated or not.

[0052] From the above, it can be seen that when harvested white asparagus is irradiated with white light for one hour every day and with far-red light constantly, the discoloration of the white asparagus can be suppressed to the same extent as when it is stored in a dark place. [Explanation of symbols]

[0053] 1 Color suppression light source 2 white light source 3 Far-red light source

Claims

1. a first irradiation step of irradiating white asparagus during cultivation or after harvest with far-red light and light in a wavelength range other than far-red light; a second irradiation step of irradiating the white asparagus with far-red light alone; A method for inhibiting discoloration, comprising:

2. Light in a wavelength range other than far-red light is irradiated during the handling of the white asparagus, and the far-red light is irradiated constantly or intermittently. The method for inhibiting discoloration according to claim 1 .

3. Light in wavelength ranges other than far-red light is irradiated within a range of 5 minutes to 3 hours per day. The method for inhibiting discoloration according to claim 2.

4. Light in wavelength ranges other than far-red light is white light. The method for inhibiting discoloration according to claim 1 .

5. The illuminance at the position where the white asparagus is present is set within a range of 300 lux to 800 lux. The method for inhibiting discoloration according to claim 1 .

6. A stain suppression system installed in a light-shielded building, a first light source that irradiates white asparagus during cultivation or after harvest with light in a wavelength range other than far-red light; a second light source that irradiates the white asparagus with far-red light; a control device that is communicably connected to the first light source and the second light source, and that controls the first light source and the second light source so that the first light source and the second light source irradiate far-red light and light in a wavelength range other than far-red light, and then irradiate far-red light alone; Discoloration suppression equipment.

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