Fruit sunburn prevention agent and method for preventing fruit sunburn

Abstract

To provide a fruit sunburn prevention agent and a method for preventing sunburn on fruit that can suppress the remaining whiteness on the fruit surface while providing sufficient sunburn protection. [Solution] The sunburn prevention agent contains calcium, which is eggshell calcium. The eggshell calcium is mixed with a solvent to form a mixture, which is then applied to the fruit for use.

Description

Technical Field

[0001] The present invention relates to a fruit sunburn preventive agent and a method for preventing fruit sunburn.

Background Art

[0002] For example, fruits such as apples, grapes, peaches, cherries, pears, persimmons, blueberries, oranges, etc., and fruits of vegetables such as watermelons, melons, tomatoes, eggplants, strawberries, cucumbers, etc. may suffer sunburn during cultivation. Sunburn is thought to occur when epidermal cells and the wax layer are heated to a high temperature by sunlight and are altered, resulting in abnormal promotion of transpiration. Fruits with sunburn have a significantly reduced commercial value because their epidermis changes to brown or black.

[0003] As a sunburn prevention measure, shading by covering with a net or a bag may be carried out. However, covering with a net or a bag has poor work efficiency and is not favorable in a production site where the producers are aging.

[0004] Therefore, as another sunburn prevention measure, a technique of spraying a calcium material mainly composed of calcium carbonate or the like onto fruits has also been developed. In this technique, in addition to the shading effect by the sprayed material covering the epidermis of the fruit, it is considered that calcium is absorbed from the epidermis and strengthens the epidermal cells, thereby having an effect of preventing sunburn (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Conventional calcium-based materials primarily consist of calcium carbonate derived from ore. To obtain sufficient light-blocking and sunburn prevention effects with such calcium materials, it is necessary to spray them at such high concentrations that the surface of the fruit turns completely white. In this case, a significant amount of white remains on the surface of the fruit at harvest and shipping, resulting in an unsightly appearance. Furthermore, consumers may mistake the whiteness for pesticides, which also reduces the market value. Therefore, wiping is necessary before shipping, but simply wiping lightly is insufficient to remove the whiteness, leading to a decrease in work efficiency.

[0007] This invention has been made in view of the above problems, and aims to provide a fruit sunburn prevention agent and a method for preventing sunburn on fruit that can suppress the remaining whiteness on the fruit surface while obtaining a sufficient sunburn prevention effect. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, we have come up with the following invention.

[0009] [1] A fruit sunscreen containing eggshell calcium. [2] In the fruit sun protection agent described in [1] above, the mixture of eggshell calcium and solvent is applied to the fruit and used. A fruit sunburn protectant wherein the concentration of eggshell calcium in the mixture at the time of use is 2.5% or less. [3] In the fruit sun protection agent described in [1] or [2] above, the mixture of eggshell calcium and solvent is applied to the fruit and used. A fruit sunburn protectant wherein the concentration of eggshell calcium in the mixture at the time of use is 0.5% or more. [4] A fruit sunscreen according to any one of [1] to [3] above, wherein the biosynthesis of pigments contained in the fruit is promoted by irradiation with ultraviolet light. [5] A fruit sunscreen according to any one of [1] to [4] above, wherein the fruit contains anthocyanin pigments. [6] The fruit sunscreen according to [4] or [5] above, wherein the fruit is an apple or a grape. [7] A method for preventing sunburn on fruit, which involves applying a mixture of eggshell calcium and a solvent to which the concentration of eggshell calcium is 2.5% or less. [Effects of the Invention]

[0010] Eggshell calcium (calcium derived from eggshells) has a porous structure, and when applied to the surface of fruit, it is thought that the temperature rise of the fruit surface is suppressed by the air within the porous structure, even when the fruit is exposed to strong sunlight. Therefore, it is presumed that it can reduce damage to epidermal cells and the wax layer, and compared to conventional mineral-derived calcium carbonate, it is possible to prevent sunburn even at low concentrations. Thus, it is possible to obtain sufficient sunburn prevention while suppressing the remaining whiteness on the surface of the fruit. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram showing the condition on day 1 of the comparative trial. [Figure 2] A diagram showing the condition on the second day of the comparative trial. [Figure 3] A diagram showing the condition on the third day of the comparative trial. [Figure 4] This diagram shows the condition three days after the application of a sunburn prevention agent. [Figure 5] This diagram shows the condition three days after applying a commercially available calcium supplement. [Figure 6] This diagram shows the condition of an untreated individual on the third day. [Modes for carrying out the invention]

[0012] The fruit sunburn prevention agent according to the present invention contains eggshell calcium. Eggshell calcium will be described below. In this specification, unless otherwise specified, mass percent is expressed as percent.

[0013] <Eggshell Calcium> Eggshell calcium is calcium made from eggshells as raw materials. For example, an egg from which egg white and egg yolk have been removed is washed with water to remove the remaining egg white and eggshell membrane, dried by well-known drying methods such as dry drying or wet drying, and further pulverized with a pulverizer to obtain it. Note that eggshell calcium may also be obtained through various processes such as a sterilization process, a purification process, a process for adjusting the particle size, etc. in addition to the above steps. Also, eggshell calcium may be calcined calcium subjected to high-temperature treatment or uncalcined calcium not subjected to high-temperature treatment.

[0014] From the viewpoints of improving the solubility in water and dispersibility, improving the runoff rate due to rainfall after spraying, preventing clogging of the sprayer, etc., the average particle size of powdery eggshell calcium is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less. Note that the smaller the average particle size of eggshell calcium, the more possible it is to reduce the whiteness when attached to the fruit surface. However, from the viewpoint of suppressing the remaining of eggshell calcium that is difficult to visually recognize or cannot be visually recognized during the wiping operation at the time of harvesting or shipping (suppressing the remaining wiped eggshell calcium that is difficult to visually recognize or cannot be visually recognized), for example, 0.5 μm or more is preferable, 0.8 μm or more is more preferable, and 1 μm or more is even more preferable. In this specification, the average particle size of eggshell calcium is a value measured by laser diffraction.

[0015] The type of raw material of the eggshell calcium used in the present invention is not particularly limited, but chicken eggs are preferable. Note that eggshell calcium may be commercially available, and for example, "Calhope" manufactured by Kewpie Co., Ltd. etc. may be mentioned.

[0016] <Other Components> The sunburn preventive agent is a material containing powdered eggshell calcium or a slurry-like material obtained by mixing eggshell calcium with a solvent (such as water), with eggshell calcium as the main component, and is used after being mixed with a solvent (such as water). In this case, other components may be contained as long as the effects are not impaired. Other components are appropriately selected according to the purpose of use, and examples include antioxidants, pH adjusters, preservatives, colorants, agricultural chemical components, fertilizer components, fragrances, colorants, surfactants (emulsifiers, dispersants), etc. Also, the solvent when making the slurry-like material and the solvent during use are not limited to water, and may be, for example, organic solvents such as alcohol and acetone, or a mixture of water and an organic solvent.

[0017] <Concentration> When indicating the concentration of eggshell calcium in this specification, it refers to the weight percentage of eggshell calcium with respect to the entire mixture when mixed with a solvent such as water during use.

[0018] From the viewpoints of improving the wiping workability during harvesting and shipping and preventing clogging of the sprayer, etc., the concentration of eggshell calcium is preferably 2.5% or less, more preferably 2% or less, and even more preferably 1.5% or less. Also, from the viewpoint of obtaining a sufficient sunburn prevention effect, it is preferably 0.5% or more, more preferably 0.8% or more, and even more preferably 1% or more.

[0019] <Usage method> Mix the sunburn preventive agent containing powdered eggshell calcium or the slurry-like sunburn preventive agent obtained by mixing a solvent and eggshell calcium with a solvent such as water, and attach the prepared mixture to the target fruits. As a method of attachment, it is advisable to spray or atomize with a speed sprayer or a sprayer, or apply with a brush, etc.

[0020] In this case, it is advisable to attach the above mixture to the target fruits during the period when high temperatures at which damage due to sunburn may occur are predicted (for example, July to August, summer). Target fruits include fruits such as apples, grapes, peaches, cherries, pears, persimmons, blueberries, oranges, etc., and vegetables such as watermelons, melons, tomatoes, eggplants, strawberries, cucumbers, etc.

[0021] As described above, eggshell calcium has a porous structure, so it is presumed that applying a mixture with a sunburn prevention agent to the surface of the target fruit will suppress the rise in temperature of the fruit surface even when exposed to strong sunlight. Compared to conventional mineral-derived calcium carbonate, it is possible to prevent sunburn even at low concentrations. Furthermore, due to its porous structure, eggshell calcium dissolves or disperses more easily in water than mineral-derived calcium carbonate, so after application, it is easily washed away from the fruit surface by rainfall, reducing the possibility of sunburn prevention agent remaining on the surface at harvest or shipping. As a result, it is possible to obtain sufficient sunburn prevention while suppressing the remaining whiteness on the fruit surface.

[0022] In particular, for fruits whose harvest season is from summer to autumn (for example, for apples, very early varieties such as "Hayate" and "Hanaiwai," early varieties such as "Beni Natsu" and "Shinano Red," and mid-season varieties such as "Tsugaru" and "Honoka"), the period from application of sunburn prevention agents to harvest tends to be shorter, and the fruits are less likely to be exposed to rain, compared to fruits whose harvest season is in winter (for example, for apples, late varieties such as "Fuji" and "Kinsei"). Therefore, with conventional mineral-derived calcium carbonate agents, in order to obtain sufficient sunburn prevention, both the concentration used and the period after application tend to result in a large proportion of the fruit surface remaining whitish at the time of harvest or shipment. In contrast, with sunburn prevention agents, since less whitish residue remains on the fruit surface after application, it is possible to use them while obtaining sufficient sunburn prevention even for fruits where the period from application to harvest tends to be short.

[0023] Furthermore, eggshell calcium is naturally derived, designated as a food additive, and its safety for human consumption has been proven at a food-grade level. Therefore, even if the sunburn prevention agent is visibly present on the surface of the fruit, it is expected to prevent a decline in consumer purchasing intent.

[0024] Furthermore, by using eggshells, which were previously considered waste from edible chicken eggs, as a raw material for sunburn prevention agents, it is possible to reduce the environmental burden and improve the product image and value of fruits treated with sunburn prevention agents.

[0025] For fruits that are colored by anthocyanin pigments, such as apples, grapes, strawberries, blueberries, and eggplants, sunburn inhibitors can be used during the fruit coloring period (mainly just before harvest, more specifically from one week to one month before harvest).

[0026] Here, fruits colored by these anthocyanin pigments require sunlight (ultraviolet light) for their coloration (biosynthesis of anthocyanin pigments). Conventional calcium materials have the problem that spraying them turns the surface of the fruit completely white, blocking sunlight and resulting in poor fruit coloration, which can also lead to a decrease in commercial value.

[0027] In contrast, with sunburn prevention agents, even at low concentrations, sufficient sunburn prevention is achieved as described above. As a result, the surface of the fruit does not become significantly white, and since the solution becomes transparent when dissolved in water, it is possible to expose the fruit surface to an appropriate amount of sunlight (ultraviolet rays). This makes it possible to promote coloring while providing sufficient sunburn prevention for fruits that require sunlight for coloring.

[0028] In particular, for fruits harvested from summer to autumn, the fruit coloring period often coincides with the period when sunburn damage is most likely to occur (summer). Therefore, with conventional mineral-derived calcium carbonate agents, even though sunburn is likely to occur, the use of calcium carbonate agents was often refrained from in order to prioritize coloring. In contrast, sunburn prevention agents can provide sufficient sunburn protection without hindering coloring.

[0029] Furthermore, any fruit containing anthocyanin pigments can be expected to promote coloring, and preferably the fruit has anthocyanin pigments as its main pigment. Other fruits may also contain flavonoid pigments such as chalcones, flavones, and flavonols as other pigments. The form of the anthocyanin pigment in the fruit may be anthocyanidins (cyanidin, peonidin, pelargonidin, delphinidin, malvidin, petunidin, etc.) consisting only of the aglycone portion that is not bound to sugars or organic acids, or anthocyanins to which sugars or organic acids are bound. The type of sugar or organic acid bound to the anthocyanidin is not limited.

[0030] Furthermore, if the fruit contains pigments that require sunlight (ultraviolet rays) for biosynthesis, or pigments whose biosynthesis is promoted by irradiation with sunlight (ultraviolet rays), then both a sunburn prevention effect and a color-promoting effect can be expected. These pigments may be flavonoid pigments other than anthocyanins, carotenoid pigments, betalain pigments, or chlorophyll pigments. More specifically, any fruit whose commercial value changes depending on the amount and form of the pigment whose biosynthesis is promoted by irradiation with sunlight (ultraviolet rays) is suitable, and more specifically, sunburn prevention agents are suitable for fruits that turn red, blue, purple, or black at the time of shipment.

[0031] Furthermore, sunburn prevention agents can also be used as calcium supplements for fruit. In other words, by applying sunburn prevention agents to fruit, calcium can be absorbed through the epidermis, strengthening the epidermal cells, resulting in firmer fruit, and potentially improving taste and shelf life. Supplementing fruit with calcium is thought to be most effective in improving taste and shelf life when done just before harvest, when the fruit has grown and matured significantly. From this perspective, the fact that sunburn prevention agents do not leave much whiteness even when used just before harvest is a desirable effect. Therefore, for example, for fruits that require sunlight for coloring, spraying them just before harvest can provide sufficient sunburn prevention while minimizing whiteness at harvest and shipping, further promoting coloring, and potentially improving taste and shelf life. [Examples]

[0032] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0033] <Example 1> A mixture was prepared by mixing 5 kg of powdered eggshell calcium (manufactured by Kewpie Corporation) with 495 L of water. Specifically, 495 L of water was placed in a 500 L tank (inside a speed sprayer), 5 kg of powdered eggshell calcium was added and mixed well to obtain the mixture of Example 1 (eggshell calcium concentration 1%).

[0034] The mixture from Example 1 was sprayed onto apples on the tree before they turned red. After waiting for them to dry, five apples were harvested and stored in apple caps in a sunny location. Subsequently, sunburn, degree of coloring, and whiteness due to calcium were visually evaluated. The evaluation criteria were as follows:

[0035] • Evaluation of sunburn +++: Many individuals have severely discolored brown areas in the sun. Severe sunburn. ++: Many individuals show brown discoloration in areas exposed to sunlight. Moderate sunburn. +: Some individuals have brown discoloration in areas exposed to sunlight. Mild sunburn. -: No sunburn.

[0036] • Evaluation of color +++: Many individuals are colored red. ++: Many individuals are faintly colored red. +: Some individuals have a faint reddish tint. -: No coloring.

[0037] • Evaluation of whitening caused by calcium (necessity of wiping) +++: Completely white. Wiping required. ++: The entire surface has a slightly whitish tint. Wiping is necessary. +: Some areas have a whitish tint. No wiping is necessary, or only a light wipe is needed. -: None. No wiping required.

[0038] <Comparative Example 1> A mixture was prepared by mixing 20 kg of commercially available calcium carbonate derived from ore (limestone) with 480 L of water. Specifically, 480 L of water was placed in a 500 L tank (inside a speed sprayer), 20 kg of powdered calcium carbonate was added and mixed thoroughly to obtain the mixture of Comparative Example 1 (calcium carbonate concentration 4%).

[0039] Apples that were still on the tree before they turned red were sprayed with the mixture from Comparative Example 1. After waiting for them to dry, five apples were harvested and stored in apple caps in a sunny place. Subsequently, sunburn, degree of coloring, and whiteness due to calcium were visually evaluated. The evaluation criteria were the same as those for Example 1 described above.

[0040] <Comparative Example 2> Five apples were harvested before they turned red and were not sprayed with any of the mixtures. They were then placed in apple caps and stored in a sunny location. Subsequently, the degree of sunburn, coloring, and whitening due to calcium were visually evaluated. The evaluation criteria were the same as those for Example 1 and Comparative Example 1 described above.

[0041] Note that Example 1, Comparative Example 1, and Comparative Example 2 all used apples (Tsugaru variety) from the same tree.

[0042] [Table 1]

[0043] ·result As shown in Table 1, Figures 1-3, and Figure 6, in Comparative Example 2, sunburn symptoms appeared from day 1, and after 3 days, 4 out of 5 fruits showed severe sunburn symptoms, with one of them turning white due to sunburn (a more severe sunburn symptom, with the inside of the fruit also degenerating). However, after 3 days, the exposed parts of all fruits turned red.

[0044] On the other hand, in Comparative Example 1, as shown in Table 1, Figures 1-3, and Figure 5, although the sunburn symptoms were reduced compared to Comparative Example 2, sunburn symptoms occurred in all five individuals. Furthermore, some individuals did not show coloration even after 3 days, and the coloration was worse than in Example 1 and Comparative Example 2. The surface remained completely white even after 3 days.

[0045] In contrast, in Example 1, as shown in Table 1, Figures 1-3, and Figure 4, none of the individuals showed any signs of sunburn. Furthermore, the coloring was similar to that of Comparative Example 2, demonstrating an effect of preventing sunburn while promoting coloring. In addition, the whitening of the surface was mild, and wiping was either unnecessary or only required a light wipe.

Claims

1. A fruit sunscreen containing eggshell calcium.

2. The mixture of eggshell calcium and solvent is applied to the fruit and used. The fruit sunburn preventative according to claim 1, wherein the concentration of eggshell calcium in the mixture at the time of use is 2.5% or less.

3. The fruit sunburn preventative according to claim 2, wherein the concentration of eggshell calcium in the mixture at the time of use is 0.5% or more.

4. The fruit sunburn protectant according to any one of claims 1 to 3, wherein the biosynthesis of pigments contained in the fruit is promoted by irradiation with ultraviolet light.

5. A fruit sunscreen containing eggshell calcium, The aforementioned fruit contains anthocyanin pigments, and is used as a sunscreen for fruit.

6. The fruit sunscreen according to claim 4 or claim 5, wherein the fruit is an apple or a grape.

7. A method for preventing sunburn on fruit involves applying a mixture of eggshell calcium and a solvent, with the mixture being applied to the fruit so that the concentration of eggshell calcium is 2.5% or less.

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