JP7319613B2 - Freezing resistance imparting agent for fruit trees, method for improving freezing resistance of fruit trees, and method for recycling food waste - Google Patents

Description

TECHNICAL FIELD The present invention relates to an agent for imparting freeze resistance to fruit trees, a method for improving the freeze resistance of fruit trees, and a method for recycling food waste.

Countermeasures against rapid temperature changes are an important issue in fruit production technology. In particular, many of the citrus fruits grown in Japan are cultivated in relatively warm regions and ripen in winter. For this reason, if exposed to extremely low temperatures on the tree, the quality of the fruit may deteriorate and it may not be possible to ship it. Therefore, from the viewpoint of stabilizing the yield, there is a demand for the development of techniques for improving the frost resistance of fruit trees. For example, Patent Document 1 describes an antifreezing agent containing condensed phosphate as an active ingredient.

Japanese Unexamined Patent Application Publication No. 2004-81028

The antifreezing agent described in Patent Document 1 has been verified in Examples for its effect on cherry trees before fruiting, but its effect on citrus fruits and fruit quality has not been verified. In addition, the discovery of a new substance effective for improving the freeze resistance of fruit trees will expand the range of options for methods for improving the freeze resistance of fruit trees and contribute to the development of the fruit tree industry.

In view of the above circumstances, an object of one aspect of the present invention is to provide a novel freezing resistance imparting agent for fruit trees and a method for improving the freezing resistance of fruit trees.
Another aspect of the present invention aims to provide a novel method for recycling food waste.

Means for solving the above problems are as follows.
<1> An agent for imparting freeze resistance to fruit trees, containing at least one extract selected from the group consisting of coffee and fermented soybeans.
<2> The agent for imparting freezing resistance to fruit trees according to <1>, wherein the fruit trees are citrus fruits .
<3> The agent for imparting freeze resistance to fruit trees according to <1> or <2>, for improving the freeze resistance of fruiting trees.
<4> A method for improving the freezing resistance of fruit trees, comprising the step of bringing the freezing resistance imparting agent for fruit trees according to any one of <1> to <3> into contact with a tree body.
<5> The method for improving freezing resistance of fruit trees according to <4>, wherein the contact is performed when the minimum temperature at night is 5°C or less.
<6> A method for recycling food waste, wherein at least one food waste selected from the group consisting of coffee and fermented soybeans is used to improve the freeze resistance of fruit trees.

An object of one aspect of the present invention is to provide a novel freezing resistance imparting agent for fruit trees and a method for improving the freezing resistance of fruit trees. According to another aspect of the present invention, a novel method for recycling food waste is provided.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. However, the scope of the present invention is not limited by the following description.
In this specification, the numerical range indicated using "to" indicates the range including the numerical values before and after "to" as the minimum and maximum values, respectively.

The agent for imparting freeze resistance to fruit trees of the present invention (hereinafter also simply referred to as agent for imparting cold resistance) contains at least one extract selected from the group consisting of coffee and fermented soybeans.
The present inventors have found that a freeze resistance imparting agent containing at least one extract selected from the group consisting of coffee and fermented soybeans is effective in improving the freeze resistance of fruit trees. In particular, when the agent for imparting freezing resistance is brought into contact with a fruit tree in a fruiting state, even if the fruit is exposed to low temperatures after a long period of time from the contact, freezing and quality deterioration are unlikely to occur, and the freezing resistance is continuously improved. have understood.
Further, the present inventors' studies have revealed that the above effects are achieved without the lowering of the freezing point of the moisture contained in the fruit (supercooling phenomenon). Such knowledge has never been reported before.

Conventionally, the work of wrapping individual fruits to prevent deterioration in quality (in the case of citrus fruits, mainly the occurrence of "sagging" and "pericarp damage" due to cold weather) has become a heavy burden. rice field. In addition, quality deterioration occurred in some fruits even when bagging was performed.
Since the agent for imparting freeze resistance of the present invention can be brought into contact with fruit trees by a method such as spraying, it is possible to significantly save labor compared to manual work such as bagging. In addition, it is possible to reduce the discard rate at the time of shipment sorting, and to improve profitability.

Since the extract contained in the agent for imparting freeze resistance of the present invention is a food-derived component, it has no risk of causing side effects on living bodies and the environment, and is excellent in safety.
The freeze-tolerant agent may contain either the coffee or fermented soybean extract alone, or may contain both the coffee and fermented soybean extracts.

The concentration of the extract contained in the agent for imparting freezing resistance is not particularly limited, and can be selected according to the type and variety of fruit trees, the method of use, and the like. Further, the freeze resistance imparting agent may be in the form of a concentrated liquid and diluted with water or the like before use. If necessary, the freeze resistance imparting agent may further contain a component such as a spreading accelerator.

The method of obtaining the extract contained in the agent for imparting freeze resistance is not particularly limited.
For example, coffee or fermented soybean, which is the raw material of the extract, is mixed with a solvent, the extract is dissolved in the solvent, and then the residue is separated by centrifugation, filtration, etc. to turn the extract into a solution (extract liquid). may be obtained as The type of solvent is not particularly limited, and may be water or a water-soluble solvent such as alcohol, preferably water.
When the raw material contains salt content, it is preferable to carry out a treatment (desalting) to remove the salt content.

The type of coffee used as a raw material for the extract is not particularly limited, and can be selected from those that are generally used as a raw material for coffee as a beverage. From the viewpoint of effective utilization of food waste, the raw material coffee may be the residue left over after brewing coffee as a beverage, unnecessary inventory, or the like.

The type of fermented soybean used as the raw material of the extract is not particularly limited, and can be selected from general fermented soybean foods such as miso and soy sauce. From the viewpoint of effective utilization of food waste, the fermented soybean as a raw material may be a residue generated when producing a fermented soybean food, an unnecessary inventory, or the like.

The method of using the antifreeze improver is not particularly limited. For example, it can be used under the conditions described in relation to the method for improving the freezing resistance of fruit trees, which will be described later.

<Method for improving freeze resistance of fruit trees>
The method for improving the freeze resistance of fruit trees of the present invention (hereinafter also simply referred to as the method for improving the freeze resistance) includes the step of bringing the above-described freeze resistance imparting agent of the present invention into contact with tree bodies.

According to the method for improving freeze resistance of the present invention, the freeze resistance of fruit trees is effectively improved.
It is preferable that the freeze resistance imparting agent is brought into contact with the fruiting tree. By bringing the freeze-resistant agent into contact with the fruiting tree body, deterioration in the quality of the fruit can be effectively suppressed.

The method of contacting the frost resistance imparting agent with the tree body is not particularly limited. For example, it may be sprayed on trees by a general method. The part of the tree that is brought into contact with the agent for imparting frost resistance is not particularly limited, and may be fruits, leaves, branches, trunks, or the like. From the viewpoint of suppressing quality deterioration of the fruit, it is preferable to bring the freeze-tolerant agent into contact with at least the surface of the fruit.

The type of fruit tree with which the agent for imparting freeze resistance is brought into contact is not particularly limited, and can be selected from citrus fruits, peach, persimmon, pear, grape, apple, kiwi, plum, mango, and the like. From the viewpoint of sufficiently obtaining the effect of improving the freeze resistance, the fruit tree with which the agent for imparting freeze resistance is brought into contact is preferably of a type whose fruit matures in a low temperature period, and is more preferably a citrus fruit.

The number of times the frost resistance imparting agent is brought into contact with the tree body is not particularly limited. Since the agent for imparting freeze resistance of the present invention contains an extract obtained from coffee or fermented soybean, it can be used without limiting the number of times in consideration of the effects on the living body and the environment. From the viewpoint of effectively improving the frost resistance, the contact of the frost resistance imparting agent with the tree body is preferably carried out two or more times, more preferably three or more times.

There is no particular limitation on the timing of contacting the tree body with the agent for imparting freezing resistance. For example, it is effective to contact at least once when the lowest temperature at night is 5°C or less, but in order to prepare for cold weather damage out of season, it is also effective to contact when the lowest temperature is over 5°C at night. is.

<How to reuse food waste>
The food waste recycling method of the present invention (hereinafter also simply referred to as the recycling method) comprises using at least one food waste selected from the group consisting of coffee and fermented soybeans to improve the freeze resistance of fruit trees. This is a method of reusing food waste.

In recent years, an increase in the amount of food waste has become a social problem, and studies on methods for effectively utilizing food waste have been advanced in many fields.
In the recycling method of the present invention, at least one food waste selected from the group consisting of coffee and fermented soybeans is used to improve the freeze resistance of fruit trees.

The food waste used in the recycling method of the present invention may be a residue obtained in the manufacturing process of coffee as a beverage or fermented soybean foods (miso, soy sauce, etc.), unnecessary inventory, etc. may be

As a method of using food waste to improve the freeze resistance of fruit trees in the recycling method of the present invention, specifically, the above-mentioned freeze resistance imparting agent is prepared from food waste and applied to the tree body. A contact method is mentioned.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these Examples.

<Preparation of antifreeze agent>
(1) 10 g of miso (rice miso) and 30 ml of distilled water were added to a 50 ml conical tube and stirred to obtain an aqueous solution of miso. Next, centrifugation was performed at 12,000 rpm for 15 minutes to remove salt from the aqueous solution, and the supernatant was removed. 30 ml of distilled water was added to the precipitate, and centrifugation was performed twice in the same manner as above. After that, the supernatant was removed from the precipitate and the precipitate was transferred to a 300 ml Erlenmeyer flask. 40 ml of distilled water was added to one tube of precipitate, and the mixture was heated at 100° C. for 30 minutes. The heated solution was centrifuged at 12,000 rpm for 15 minutes and filtered (using No. 5 filter paper) to prepare a miso extract.

(2) A 2.5-fold amount of hot water was added to the residue (coffee grounds) after coffee extraction to obtain an extract. Extraction was carried out at 95° C. for 60 minutes using a pressure cooker and the high pressure apparatus described above. After the extraction, the residue of the coffee grounds and the extract were separated by filter filtration, and the fractional molecular weight was adjusted to 5 kDa or less with an ultrafiltration device. Furthermore, filter sterilization was performed with a 0.22 μm filter to prepare a coffee grounds extract.

(3) The miso extract and the coffee grounds extract obtained in (1) and (2) above are mixed at the ratio (volume basis) shown in Table 1 to obtain the dilution ratio (volume basis) shown in Table 1. A freezing resistance imparting agent was prepared by diluting with water as follows.

<Evaluation of freeze resistance improvement effect>
(1) As the effect of improving the freeze resistance by the freeze resistance imparting agent, the occurrence of freezing of the fruit was evaluated by the following tests.
Two cultivars of "Shiranui" and "Nantsukai" in fruiting state were used as test subjects.
On November 15th, November 29th, December 13th, December 24th, January 7th, February 4th and February 18th (conducted in fields in Nagasaki Prefecture in 2018), freeze resistance was given The agent was sprayed on the tree body (including the surface of the fruit). The control group was left unsprayed.

"Shiranui" fruits (harvested on March 1) and "Nantsukai" fruits (harvested on March 5) harvested from the trees after spraying are cooled at -5.0 ° C in the incubator (6 hours )bottom. After performing the same cooling test four times, the occurrence of freezing of the fruit was examined. Table 1 shows the results.

The "minimum temperature" listed in Table 1 is the temperature measured by inserting a thermocouple inside the fruit.
The "central pore" and "transverse diameter" described in Table 1 are the arithmetic mean values of the actual measurements of the fruit used in the test.
The "frozen ratio" shown in Table 1 is the arithmetic mean value of the numerical values obtained by cutting the fruit along the equatorial plane and examining the ratio of the frozen part from a perspective.
The "sugar content" shown in Table 1 is the arithmetic mean of the measured values of the fruits used in the test.

As shown in Table 1, in both the "Shiranui" and "Nantsukai" cultivars, the percentage of occurrence of freezing in the fruit of the group sprayed with the antifreezing agent was lower than that of the control group. The sugar content of the fruit in the group to which the anti-freezing agent was sprayed and the control group were almost the same.

(2) As the effect of improving the freeze resistance by the freeze resistance imparting agent, the occurrence of deterioration in fruit quality was evaluated by the following tests.
Specifically, under the same conditions as the test described above, the occurrence of floating skin (a phenomenon in which the peel and pulp separate) and swelling (a phenomenon in which the pulp tissue loses moisture) after cooling in the incubator was examined. rice field. Table 2 shows the results.

Note 1: Coffee grounds: miso ratio (volume basis) of 1: 1 and 1: 0.5,
Same amount for each Note 2: Spray the same amount of 100-fold dilution and 250-fold dilution Note 3: Use the same amount of 100-fold dilution and 250-fold dilution and scatter

Occurrence of floating skin or swelling described in Table 2 was evaluated according to the following criteria from the condition of the pulp when observing the cross section when the fruit was bisected horizontally.
0: No floating skin or swelling occurred in any pulp.
1: Less than 20% of the pulp has floating skin or swelling.
2: 20% or more and less than 50% of the pulp has floating skin or swelling.
3: Over 50% of the pulp has floating skin or swelling.

The occurrence rate of floating skin or hanging up described in Table 2 is a value obtained by multiplying the value obtained by dividing the number of fruits corresponding to the above criteria 1 to 3 by the number of samples and multiplying by 100.
The floating skin or swelling index described in Table 2 is a value calculated by the following formula.
Index = {(1 x number of fruits of reference 1) + (2 x number of fruits of reference 2) + (3 x number of fruits of reference 3)} / (3 x number of samples) x 100

The significant difference described in Table 2 was calculated by the Mann-Whitney test for the floating skin or swelling index, and by the t-test for the other items. NS indicates no significant difference, * indicates a significant difference at the 5% level, and ** indicates a significant difference at the 1% level.

As shown in Table 2, in both the "Shiranui" and "Nantsukai" varieties, the fruit of the group sprayed with the antifreezing agent had a lower rate of floating skin and swelling than the control group.
The above results demonstrate that the freeze resistance improver of the present invention sustainably improves the freeze resistance of fruit trees.

<Consideration of the mechanism of the effect of improving freeze resistance>
In order to examine the mechanism by which the freeze resistance improver of the present invention improves the freeze resistance of fruit trees, the following tests were conducted.
The miso extract and the coffee grounds extract prepared by the above-described method were each diluted with water to a dilution ratio of 500 times (on a volume basis) to prepare cold resistance imparting agents.

As a composition for comparison, an aqueous solution of melanoidin was prepared. Melanoidins are substances obtained by the reaction of reducing sugars and amino acids, and are reported to have the effect of promoting the supercooling phenomenon of water (for example, JP-A-2019-6883). The melanoidin used in this example was synthesized by the method described in the example of the above publication using glucose as a reducing sugar and glycine as an amino acid.

Under the same conditions as the test described above, a freeze-tolerant agent containing miso extract (group A), a freeze-tolerant agent containing coffee grounds extract (group B), and a comparative composition containing melanoidin (group C) were prepared as follows: Shiranui” (January 16th, January 19th, January 20th, January 27th, January 29th, February 1st, February 14th, February 17th and February 18th) (Implemented in fields in Nagasaki Prefecture in 2017). The control was no spraying (group D), and the fruits were harvested on February 20th for all groups.

The harvested fruits (8 for each group) were cooled in an incubator (internal temperature set to -6.0°C for 7 hours). After conducting the same cooling test twice, the occurrence of freezing of the fruit was investigated. Table 3 shows the results.

"Minimum temperature", "central pore", "transverse diameter", "freezing ratio" and "sugar content" shown in Table 3 are values obtained in the same manner as the items shown in Table 1.
The "time from the start of cooling to freezing" in Table 3 is the time from the start of cooling to the time when it is assumed that the fruit is frozen from the value indicated by the thermocouple inserted in the fruit.
The "frozen portion" in Table 3 is the arithmetic mean value of the measured diameters of the portion of the fruit where freezing occurred.

As shown in Table 3, the fruits of group A sprayed with the freeze-tolerant agent containing miso extract and group B sprayed with the freeze-tolerant agent containing coffee grounds extract were sprayed with the comparative composition containing melanoidin. The percentage of freezing of the fruit was lower than that of the group C and the non-sprayed group D.
Group C, to which the melanoidin-containing comparative composition was sprayed, had a minimum temperature comparable to that of the other groups, and no supercooling-enhancing effect (decrease in minimum temperature) was observed.
From the above results, it was found that the decrease in the percentage of frozen fruit due to the pre-harvest spraying of the antifreeze agent was not due to the supercooling promotion effect.

Claims (5)

A freeze-tolerant agent for citrus fruit trees containing an extract of miso . The agent for imparting freeze resistance to fruit trees according to claim 1 , for improving the freeze resistance of fruiting trees. A method for improving the freezing resistance of fruit trees, comprising the step of bringing the freezing resistance imparting agent for fruit trees of claim 1 or 2 into contact with a tree body. 4. The method for improving the frost resistance of fruit trees according to claim 3 , wherein said contact is carried out when the lowest temperature at night is 5°C or less. A method for reusing food waste, wherein the food waste of miso is used to improve the freeze resistance of fruit trees that are citrus fruits.