JP2003012402A - Preserving liquid for leaf, method for preserving leaf, and leaf treated with the same method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preserving plant leaves without discoloration for a long period and also capable of maintaining the flexibility of them even if they are leaves turning red. SOLUTION: This method for preserving plant leaves comprises a process of immersing the leaves in a preserving liquid obtained by dissolving 0.1-3 wt.% L-ascorbic acid and/or its salts and 5-30 wt.% sodium chloride, and a process of preserving the above leaves in a state of being immersed in the preserving liquid at 0-15 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leaf preservative solution suitable for preventing discoloration of red leaves and green leaves and preserving the leaves while maintaining flexibility, and a leaf using the preservative solution. And a leaf preserved by this preservation method.

[0002]

[Prior Art and its Problems] Fresh greenery in spring and autumn foliage in autumn appeal to the mood of the Japanese people, and are added to foods to give the taste and the antibacterial action of the leaves. Many are used. For example, Kakinoha sushi, which is a traditional mackerel sushi wrapped in salted persimmon leaves in the Yoshino region of Nara prefecture, is a representative example.

However, in order to use the leaves of a real plant as described above, imitation products such as plastics and leaves which are dyed with a harmless dye are often used because they are difficult to store and distribute. .

The leaves which have been colored red are poor in flexibility because the aging of the plant body is progressing. Therefore, in order to wrap a food (for example, mackerel sushi) with the leaves that have been colored red, skilled craftsmanship is required. A green persimmon leaf can be used with an automatic wrapping device because of its flexibility, but an autumn foliage cannot use this automatic wrapping device.

The present invention was devised in view of the above circumstances and is capable of preserving plant leaves for a long period of time without fading, and maintaining flexibility even when the leaves are red leaves. It is an object of the present invention to provide a leaf preservation solution capable of producing the same, a leaf preservation method using this preservation solution, and a leaf subjected to this preservation method.

[0006]

The leaf preservation solution according to the present invention comprises 0.1 to 3% by weight of L-ascorbic acid and / or water.
Alternatively, a salt thereof and 5 to 30% by weight of sodium chloride are dissolved.

The leaf preservation method according to the present invention comprises a step of immersing the leaf in the leaf preservation solution and a step of preserving the leaf in the preservation solution at 0 to 15 ° C. Have

In particular, the immersion of the leaves in the preservation solution is
It may be carried out under a reduced pressure of × 10 ^{-1 to} 2.25 Pa.

The leaves subjected to the preservation method of the present invention are preserved by the above method.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a graph showing the effect of preventing discoloration of a preservation method using a leaf preservation solution according to the present invention, and FIG. 2 is a leaf hardness subjected to a preservation method using this preservation solution. FIG. 3 is an explanatory view showing an experimental method for measuring the leaf height, and FIG. 3 is an explanatory view showing an experimental method for measuring the bending strength of leaves subjected to the preservation method using this preservation solution.

The leaf preservation solution according to the embodiment of the present invention is
0.1 to 3% by weight of L-ascorbic acid in water, 5 to 3
It is a solution in which 0% by weight of sodium chloride is dissolved.

Chlorophyll, which is the main constituent of the green color of plant leaves, and anthocyan, which is the main constituent of the crimson color of autumnal leaves, are originally chemically unstable substances and easily discolor by oxidation. It utilizes the antioxidant effect of L-ascorbic acid to prevent discoloration due to oxidation.

[0013] Further, sodium chloride is intended to promote the antioxidant action of L-ascorbic acid and to remove (dehydrate) water from leaf cells by osmotic pressure. Dehydration improves the flexibility of the tissues that make up the leaves. In addition, sodium chloride also has a role of preventing the propagation of various bacteria during storage.

For example, L-ascorbic acid is added to water in an amount of 0.0
Immerse red persimmon leaves in a preservative solution containing 1 to 3% by weight of sodium chloride and 5% by weight of sodium chloride.
It was confirmed by experiments that persimmon leaves retain a bright red color for 40 to 60 days when preserved in. In addition, persimmon leaves are
I used the one from Tone.

Further, when leaves of persimmon leaves which have been red-colored are soaked in a preservative solution in which 1% by weight of L-ascorbic acid and 30% by weight of sodium chloride are dissolved and stored as it is at 5 ° C.,
It was confirmed by experiments that persimmon leaves retain a bright red color after 4 months. Moreover, 20 from the storage solution
It was confirmed that the bright red color was retained for 14 days even when stored at room temperature of ° C. It was also confirmed that the leaves taken out of the storage solution had increased flexibility and were less likely to tear.

As described above, it was confirmed that dissolving at least 0.01% by weight of L-ascorbic acid was sufficient for preventing discoloration of red leaves, but from an economical viewpoint. Considering that, 1% by weight is considered to be cost-effective.

Although sodium chloride can be expected to be effective even at about 5% by weight, the concentration is preferably 20 to 30% by weight, considering that it is stored in a hygienic safe state for a long period of time.

When the step of immersing the leaves in the preservation solution is performed under reduced pressure, oxygen contained in the leaves is removed, so that oxygen causing discoloration can be removed from the leaves in advance. At the same time, the dipping work under reduced pressure has the effect of promoting the penetration of the preservation solution into the leaves. This decompression is 1.5 x 1
It is good to carry out at 0 ^{−1 to} 2.25 Pa (20 to 300 mmHg). With such a reduced pressure, it is possible to expect the effects of removing oxygen and quickly permeating the preservative while preventing the preservative from boiling.

Further, the temperature for storage is preferably as low as possible so that freezing of water contained in leaves destroys tissue cells of the leaves. Since the water content of the leaves freezes at about -2 to -1 ° C, 0 ° C higher than this is set as the lower limit. In addition, as a result of the experiment, the effect of preventing discoloration could be confirmed even at 15 ° C., but it has been confirmed that the effect can be sufficiently obtained at 5 ° C. which is the standard of the low temperature of the household refrigerator. Therefore, considering a device that keeps low temperature,
It is considered cost effective to store at about ℃. Further, 15 ° C. is a general room temperature in late autumn when persimmon leaves are collected. Therefore, use of this preservation solution enables long-term preservation even at room temperature.

The leaves preserved with such a preservation solution are washed with water and desalted before they are used in foods and the like.

Dip in a preservative solution in which 1% by weight of L-ascorbic acid and 30% by weight of sodium chloride are dissolved in water.
Table 1 below shows the color condition of the leaves when stored in. The intensity of the red color is indicated by the a value of the Lab colorimetric system. Also, if the value of a is 30 or more, "keep it vivid" is 2
Those that are 5 or more and less than 30 are represented as "slightly discolored", those that are 20 or more and less than 25 are significantly discolored, and those that are less than 20 are significantly discolored.

[0022]   (Table 1) Number of days since storage Red intensity Strength of apparent appearance of red Evaluation of green on autumn leaves   Immediately after storage 35.04 Maintain vividness Maintain vividness   Save 77 days 33.05 Keep vivid Keep vivid   Save 106 days 33.46 Keep vivid Keep vivid

After the start of storage of the leaves thus stored, 106
Table 2 below shows the color condition of leaves when taken out on the day, washed with water, dehydrated, sealed in a polyethylene bag and kept at 20 ° C. The intensity of the red color is indicated by the a value of the Lab colorimetric system.

[0024]   (Table 2) Number of days after removal Red strength Strength of apparent appearance of red Evaluation of green on autumn leaves   One day after taking out 33.28 Keeping vividness Keeping vividness   2 days after taking out 33.28 Keeping vividness Keeping vividness   3 days after taking out 32.69 Keeping vividness Keeping vividness   6 days after taking out 31.57 Keeping vividness Keeping vividness   14 days after removal 28.06 Fades slightly

As a comparative experiment, the sample was immersed in a preservative solution containing 30% by weight of sodium chloride containing no L-ascorbic acid,
Table 3 below shows the color condition of leaves when stored at 5 ° C. The intensity of the red color is indicated by the a value of the Lab colorimetric system.

[0026]   (Table 3) Number of days since storage Red intensity Strength of apparent appearance of red Evaluation of green on autumn leaves   Immediately after storage 35.04 Maintain vividness Maintain vividness   Save 106 days 24.24 Very faded Very faded

After the start of storage of the leaves thus stored, 106
Table 4 below shows the color condition of leaves when taken out on the day, washed with water, dehydrated, sealed in a polyethylene bag and kept at 20 ° C. The intensity of the red color is indicated by the a value of the Lab colorimetric system.

[0028]   (Table 4) Number of days after removal Red strength Strength of apparent appearance of red Evaluation of green on autumn leaves   1 day after taking out 24.24 Fading considerably   2 days after taking out 23.64 Discolored considerably Discolored considerably   3 days after removal 22.40 Fading considerably Fading considerably   6 days after removal 21.39 Fading considerably Fading considerably   14 days after taking out 19.37 Remarkably fading Fading considerably

As described above, it can be confirmed that if the preservation solution does not contain L-ascorbic acid, the reddish color and the green color have a large degree of fading. The graph shown in FIG. 1 is a summary of the above Tables 1 to 4.

On the other hand, the hardness of leaves, that is, the flexibility will be described. As shown in FIG. 2, a hole 11 of 1.5 cm in the center
Leaves L on a plastic plate 100 with a diameter of 0 and a diameter of 15 cm
While sandwiched from both front and back sides and fixed (Fig. 2 (A)
5) through the hole 110 to the cylinder 120 having a diameter of 5 mm.
When it is lowered at a speed of mm / sec and pressed against the leaf L (Fig. 2
(See (B) and (C)), the strain at which the column 120 contacts the leaf L until the leaf L breaks (see FIG. 2D).
Was measured as.

Further, as shown in FIG. 3, when both ends of the leaf L are held by hand and slowly wound on the longer side of the leaf (see FIG. 3).
(See (A)), and the diameter of the ring formed by the leaves L at the limit of breaking the leaves L (see FIGS. 3B and 3C) was measured as the leaf bending strength. The results of these measurements are shown in Table 5. Sample 1 is a salted green persimmon leaf (a persimmon leaf that is commonly used for persimmon leaf sushi), sample 2 is a persimmon leaf immediately after collection, and sample 3 is a red leafed persimmon leaf on the 77th day of storage. And

[0032]   (Table 5)                       Sample 1 Sample 2 Sample 3 Breaking strain (mm) 2.60 2.15 2.66 Leaf bending strength (cm) 1 cm or less 10 cm or so 1 cm or less

From the results of this experiment, the sample 77, the preservation 77
It can be confirmed that the persimmon leaves which had red leaves on the day have almost the same properties as the salted green persimmon leaves that are usually used for persimmon leaf sushi.

Although L-ascorbic acid is used in the above-mentioned embodiment, the same effect can be obtained with L-ascorbic acid stearic acid ester or salts of L-ascorbic acid such as sodium L-ascorbic acid. Can be expected. They are also safe because they are permitted by the Food Sanitation Law.

[0035]

EFFECTS OF THE INVENTION The leaf preservation solution according to the present invention is 0.1% in water.
˜3 wt% L-ascorbic acid and / or its salts and 5 to 30 wt% sodium chloride are dissolved.

It was confirmed that when leaves were dipped in this preservation solution and kept at 0 to 15 ° C., the vividness and flexibility of the red color were maintained for a long period (at least 106 days). Also,
Even if it is taken out from the preservation solution after that, for at least 6 days,
It was confirmed that the vividness and flexibility of the crimson color were maintained.
Thus, by using this leaf preservation solution, the red leaves can be preserved for a long period of time and the flexibility can be maintained. Also, the vividness and flexibility of the color can be maintained even after taking out from the storage solution. Therefore, by using this leaf preservation solution, it is possible to use leaves that have been colored red in autumn in winter, which has been impossible until now, as food supplements in winter. Being able to use it in the winter means that it can be used for New Year's cuisine, which requires a great deal of congratulations, so it can be said to bring new demand. In particular, since persimmon leaves that are simply colored leaves lack flexibility, when trying to wrap a food product (for example, mackerel sushi), skilled craftsmanship was required and the automatic packaging device could not be used. The automatic packaging device can be used as long as it is stored in this storage solution.

On the other hand, the method for preserving leaves according to the present invention comprises a step of immersing the leaves in the preservative solution for the leaves and a step of keeping the leaves in the preservative solution at 0 to 15 ° C. I have it.

[0038] According to this storage method, it is possible to maintain a leaf which retains a bright red color and flexibility for a long period of time.

Particularly, the immersion of the leaves in the preservation solution is 1.5 × 1.
When the pressure is reduced to 0 ^{-1 to} 2.25 Pa, oxygen that causes discoloration can be removed from the leaves in advance, and at the same time, the penetration of the preservation solution into the leaves can be promoted. Further, when the pressure is reduced to such a level, it is possible to expect the effects of removing oxygen and quickly permeating the preservative while preventing the preservative from boiling.

Furthermore, the leaves subjected to the preservation method characterized by being preserved by the above-mentioned method can maintain the crimson color and the flexibility which are known for a long period of time. Therefore, it becomes possible to wrap the food using the automatic packaging device.

[Brief description of drawings]

FIG. 1 is a graph showing the effect of preventing discoloration of a storage method using a leaf storage solution according to the present invention.

FIG. 2 is an explanatory diagram showing an experimental method for measuring the hardness of leaves subjected to a storage method using this storage solution.

FIG. 3 is an explanatory diagram showing an experimental method for measuring the bending strength of leaves that have been subjected to a storage method using this storage solution.

Claims (4)

[Claims] 1. A leaf preservation solution characterized in that 0.1 to 3% by weight of L-ascorbic acid and / or its salts and 5 to 30% by weight of sodium chloride are dissolved in water. 2. A step of immersing a leaf in the leaf preservation solution according to claim 1, and 0 in a state where the leaf is immersed in the preservation solution.
A method for preventing discoloration of leaves, comprising the step of maintaining the temperature at -15 ° C. 3. The immersion of the leaves in the preservation solution is 1.5 × 1.
The leaf preservation method according to claim 2, wherein the preservation is performed under a reduced pressure of 0 ^{-1 to} 2.25 Pa. 4. A leaf subjected to a preservation method, which is preserved by the method according to claim 2 or 3.