JP2000116317A - Freezing leaf vegetable and pickle comprising frozen leaf vegetable obtained by the freezing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To freeze a leaf vegetable by a simple operation so as to improve excellent shelf stability and to obtain a high nutritive value and excellent texture by cleaning the leaf vegetable, preserving in salt, dehydrating and quickly freezing the leaf vegetable. SOLUTION: A leaf vegetable is cleaned, the cleaned leaf vegetable is preserved in salt and dehydrated. The dehydrated leaf vegetable is quickly frozen. In the operation, in order to clean the leaf vegetable, preferably one or more of an aqueous solution of hypochlorous acid compound, an aqueous solution of chlorine dioxide, ozonous water and an aqueous solution of a cationic or amphoteric surfactant are used. Preferably, the freezing temperature is -20 to -60 deg.C when the dehydrated leaf vegetable is quickly frozen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for freezing leafy vegetables which can be stored for a long time without deterioration in quality, and to a pickle using frozen leafy vegetables as a main raw material obtained by the method.

[0002]

2. Description of the Related Art Conventionally, refrigeration is mainly known as a method for preserving vegetables. However, since leafy vegetables having voids between leaves are bulky, a large-sized refrigeration apparatus is required and space saving and energy saving are required. In addition, it is difficult to store for 2 to 3 months or longer because the quality is gradually deteriorated with storage while the quality is poor. In addition, frozen vegetables, as typified by mixed vegetables, are widely known.However, freezing raw leafy vegetables in the usual manner causes free water and bound water in cells to produce large ice crystals. There is a problem that the cell membrane is easily broken and it is difficult to maintain the quality. In recent years, various methods of freezing vegetables and pickles using frozen vegetables have been studied. For example, 1) Japanese Patent Publication No. 51-6225 (hereinafter referred to as "A") discloses that vegetables are frozen, thawed, pressed, dehydrated, and vinegared.
A pickle pickled in bran, lees, miso and the like is disclosed. 2) Japanese Patent Laying-Open No. 52-18857 (hereinafter referred to as "B") discloses a freezing method in which vegetables once processed into pickles are packed in a container filled with salt water and frozen. 3) JP-B-63-60989 (hereinafter referred to as "C" publication) discloses a cooling brine or a low-boiling liquefied gas filled in an antifreeze liquid tank having an open upper portion, in which the upper portions of containers, trays, flat plates and the like are opened. Contact one side of the heat transfer means
A refrigeration method is disclosed in which an object to be frozen is brought into contact with the other surface of the heat transfer means and freezing proceeds only from the contact surface with the heat transfer means.

[0003]

However, the above-mentioned conventional freezing methods and pickles have the following problems. 1) Since the pickles described in JP-A No. 1 are generally frozen, the cell membrane of the vegetables is destroyed when the ice crystals grow on the cell membranes during the freezing, and the vegetables are pressed and dehydrated. Since a large amount of minerals and the like flow out, the quality is remarkably deteriorated, such as a decrease in taste and nutritional value, and there is a problem that the texture such as a chewy texture when processed into pickles is deteriorated. 2) The freezing method described in the publication (b) requires a large amount of salted water, which requires a large amount of salted water, because it is immersed in salted water and frozen after being processed into a pickle, and it takes time to thaw. And 1) above. 3) The freezing method described in the publication No. C discloses that freezing proceeds only from the portion in contact with the heat transfer surface, so that when applied to leafy vegetables such as Chinese cabbage having a gap between leaves, it takes a long time to freeze the whole. However, since ice crystals grow and become large, the cell membrane is destroyed, and there is a problem that the taste and nutritional value are inferior.
In addition, there is a problem that freezing and burning are apt to occur and the product yield is low. Furthermore, in order to freeze a large amount of leafy vegetables, a large-sized refrigerant container having a large surface area is required, so that space saving is not achieved, and a long time is required for work, and energy saving is not sufficient. Was.

[0004] The present invention solves the above-mentioned conventional problems, and provides a method for freezing leafy vegetables, which can obtain frozen leafy vegetables having excellent preservability, high nutritive value and excellent texture by a simple operation, and The objective is to provide a pickle that is excellent in umami and retains excellent nutritional value by using the frozen leafy vegetables obtained thereby.

[0005]

In order to solve the above-mentioned conventional problems, a method for freezing leafy vegetables according to the present invention comprises a washing step of washing the leafy vegetables, and a salt for pickling the leafy vegetables washed in the washing step. It has a configuration including a pickling step, a draining step of draining the leafy vegetables pickled in the salting step, and a freezing step of rapidly freezing the leafy vegetables drained in the draining step. With this configuration, leafy vegetables that are difficult to store for a long time in refrigeration can be stored for a long time without deterioration in quality. In addition, since free water and bound water in cells are frozen in a very short time by rapid freezing, the ice crystals become extremely fine, so that the cell membrane of leafy vegetables is not destroyed, and it is placed in cells and tissues such as fibers. The nutrients and umami components contained therein can be kept in the leafy vegetables without flowing out. Since ice crystals do not grow due to rapid freezing, destruction of tissues such as cells of fibers is prevented, and as a result, texture can be maintained, and cells and fibers are destroyed by growth of ice crystals as in the conventional case, and umami components flow out. And the problem of texture loss. Further, the pickles of the present invention have a configuration in which the frozen leafy vegetables obtained by the above-mentioned freezing method are the main raw materials. With this configuration,
It has almost the same chewyness and taste as fresh vegetables, and you can eat pickles of excellent quality and nutritional value using high quality frozen leafy vegetables with flavor, nutritional value and texture throughout the season.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A method for freezing leafy vegetables according to claim 1 of the present invention comprises a washing step of washing the leafy vegetables, a salting step of salting the leafy vegetables washed in the washing step. It has a configuration including a draining step of draining the leafy vegetables pickled in the salting step, and a freezing step of rapidly freezing the leafy vegetables drained in the draining step. According to this configuration, the surface of the leafy vegetables and various germs can be removed in the washing step, so that there is an effect that deterioration in quality can be suppressed. The salting step removes excess water and softens the leaves, so large vegetables such as Chinese cabbage can be reduced by half.
Since the volume can be reduced to about １ ／ and the refrigeration efficiency can be increased, there is an effect that space saving and energy saving during freezing and storage can be improved. Since excess water can be removed in the draining step, it is possible to reduce the size and weight, to save energy during freezing, and to reduce the transportation cost. In addition, because of the rapid freezing in the freezing step, ice crystals do not grow in the leafy vegetables, which can prevent cell membrane destruction and can be preserved without reducing the taste and nutritional value. Have. It has the effect that inexpensive and delicious seasonal leafy vegetables can be stored for a long time without deteriorating the quality. Since it is in a slightly pickled state by salting, it can be processed into various pickles immediately by seasoning with a predetermined seasoning liquid or the like.

Here, leaf vegetables include cabbage, Chinese cabbage,
Nozawana, Takana, wasabi leaves, mustard greens, green onions and the like are used. In addition, although it is not leafy vegetables, onions and the like can also be used. The washing step may include, if necessary, a hypochlorite compound such as sodium hypochlorite, a bactericidal compound such as chlorine dioxide, ozone water, hydrogen peroxide water, or a cationic or amphoteric surfactant. Using the water containing the above chemicals, the leafy vegetables are washed by dipping or shaking. In the salting step, although it depends on the type of leafy vegetables, etc., the leafy vegetables are pickled with 1 to 30% by weight of salt, and if necessary, washed with water after salting to remove excess salt. In the draining step, the salted leafy vegetables are arranged in a colander or the like and drained naturally or by applying pressure as necessary. In the freezing process, the leafy vegetables are conveyed to a tunnel-type freezer on a belt conveyor, and air blasting, in which low-temperature air is sprinkled, semi-air blasting, or liquid refrigerant freezing, in which liquid nitrogen, liquefied carbon dioxide, liquid freon, etc. are sprinkled, etc. It is preferable to perform rapid freezing, but if rapid freezing can be performed, it may be performed in a batch method or the like in which the liquid is kept in a low-temperature liquid or gas at a predetermined temperature for a certain time.

The method for freezing leafy vegetables according to the second aspect of the present invention is the method for freezing leafy vegetables according to the first aspect, wherein the washing step includes an aqueous solution of a hypochlorite compound, an aqueous solution of chlorine dioxide,
It has a configuration in which one or more of ozone water and an aqueous solution of a cationic or amphoteric surfactant is used. With this configuration, it is possible to kill germs attached to leafy vegetables with many voids between leaves in a short time and suppress deterioration in quality, and to easily reduce the amount of residual drug to a safe value by washing with water. Has the effect of being able to. Here, the aqueous solution of hypochlorous acid compound or aqueous solution of chlorine dioxide may be used alone or as a mixed aqueous solution thereof.
ppm, preferably 0.01 to 10 ppm is used. As the concentration becomes lower than 0.01 ppm, the sterilizing power tends to be inferior and sufficient sterilization cannot be performed. As the concentration becomes higher than 10 ppm, a long time is required for washing with water and the amount of residual chlorine tends to increase. Not preferred. Ozone water having a concentration of 0.1 to 15 ppm, preferably 1.3 to 10 ppm is used. 1.
When the amount is less than 3 ppm, the bactericidal properties tend to be lacking, and when the amount exceeds 10 ppm, there is a tendency to deteriorate the environment due to ozone odor and the like.

The method for freezing leafy vegetables according to claim 3 of the present invention is the method for freezing leafy vegetables according to claim 1 or 2, wherein the freezing temperature in the freezing step is −20 ° C. to −60 ° C., preferably − It has a configuration of 30 ° C to -60 ° C. With this configuration, leafy vegetables can be quickly frozen, and the combined water and free water of the tissue are frozen into small ice crystals and do not damage cell membranes or tissues, so they have little effect on texture and taste. Has an action. Since damage to tissues such as cell membranes can be prevented, there is an effect that umami components, nutrients, and texture can be prevented from being impaired. here,
As the refrigerating device, one that directly acts on a low-temperature refrigerant or cooling air is preferably used. A continuous refrigerating device such as a tunnel type is particularly preferably used. This has the effect that continuous production of frozen leafy vegetables can be achieved and productivity and workability can be significantly increased. As the freezing temperature becomes higher than -30 ° C, free water and bound water in the cells tend to form large ice crystals, and the cell membrane tends to be destroyed. Any of these is not preferable since the burden increases and a tendency to lack energy saving properties appears.

A pickle according to a fourth aspect of the present invention has a constitution in which a frozen leafy vegetable obtained by the method for freezing a leafy vegetable according to any one of the first to third aspects is used as a main raw material. ing. With this configuration, seasonal leafy vegetables with good taste and inexpensiveness can be provided with stable quality throughout the four seasons, so that there is an effect that high-quality pickles can be obtained. In particular, since lactic acid fermentation is used, sourness becomes stronger as ripening progresses, so even in the case of kimchi that is not suitable for long-term storage, it can be added to the optimal time considering the selling time etc. It can be suitably used.

Hereinafter, the present invention will be described in more detail with reference to examples.

(Example 1) Chinese cabbage was used as a leaf vegetable, and as a preparation step, a cut was made in the core of the root of the leaf vegetable from which the soiled outer leaves had been removed, and the leaf vegetable was split vertically by hand. As a washing step, 0.
After being immersed in a 5 ppm aqueous solution of sodium hypochlorite for several minutes, it was washed twice with running water. Next, as a salting step, 5 to 7 wt% of salt based on the weight of Chinese cabbage was dusted and allowed to stand for 12 hours. The Chinese cabbage pickled in the salting step was washed with running water or pickling to adjust the salt content to 1 to 4 wt%. In the freezing step, a predetermined amount is separated into vats, and the inside of a tunnel type freezer at -40 ° C to -30 ° C is set to 1
The mixture was passed through in 5 to 40 minutes and rapidly frozen. The frozen Chinese cabbage obtained as described above was packed in a bag, a predetermined number was packed in a box, and stored in a freezer at −20 ° C. After 12 months in the freezer, they were thawed and inspected for quality. As a result, no seepage of water was observed, and it was found that an appropriate water content was maintained. Also, no yellowing or browning of the leaves was observed, indicating that there was almost no deterioration in quality.

(Example 2) Kimchi was produced by using one frozen cabbage obtained in Example 1 (about 3 kg of fresh leaves). First, 3 cups of boiled and dried, 100 g of salted Ami,
2 tablespoons of honey, 1 tablespoon of kelp tea, 10 tablespoons of powdered pepper,
2 teaspoons of salt, 5 portions of ground garlic, 20 g of grated ginger
Was prepared. Next, 400 g of shredded radish was sprinkled with 1 tablespoon of salt and squeezed, and seri and green onion were cut into 4 to 5 cm pieces each. The frozen Chinese cabbage was naturally thawed or thawed with running water and squeezed. Dried Chinese cabbage was sprinkled with sauce, sandwiched between leaves of thawed Chinese cabbage, sealed tightly in a container, and then immersed at 10 ° C for 1 day to obtain kimchi. The kimchi obtained as described above was fed to 10 test subjects together with a normal kimchi produced by the same method except that non-frozen Chinese cabbage was used. As a result, the impression that everyone was "very delicious without any difference in texture and taste" was obtained. From this, it was found that a high-quality pickle with excellent nutritional value, which is almost the same as fresh leafy vegetables, can be obtained.

[0013]

As described above, according to the first aspect of the present invention, 1) dirt and germs attached to the surface of leafy vegetables can be removed by the washing step, so that quality deterioration is prevented. can do. 2) Excessive moisture can be removed by the salting step, and the leaves can be softened and reduced in volume, thus being excellent in energy saving and space saving. 3) Since excess water can be removed, the weight can be reduced,
The cost of transportation can be reduced. 4) Because of rapid freezing, destruction of cell membranes can be minimized, and the taste and nutritional value are excellent. 5) Inexpensive and delicious seasonal leafy vegetables can be stored for a long period of time without deterioration in quality and have excellent preservability. 6) Since it is salted and lightly pickled, it can be easily processed into various pickles by seasoning it with a predetermined seasoning liquid or the like.

According to the second aspect of the present invention,
In addition to the effects of the first aspect of the present invention, it is possible to kill germs attached to the surface of leafy vegetables in a short time, so that unnecessary deterioration in quality can be avoided and safety is excellent.

According to the third aspect of the present invention,
In addition to the effects of the first or second aspect of the present invention, the leaf vegetables can be rapidly frozen, so that the destruction of the cell membrane is suppressed, and the frozen leaf vegetables excellent in texture, taste and nutritional value are obtained.

According to the invention described in claim 4 of the present invention,
Since frozen leafy vegetables of stable quality can be used throughout the four seasons, high quality pickles can be obtained.

Claims (4)

[Claims] A washing step of washing the leafy vegetables, a salting step of salting the leafy vegetables washed in the washing step, and a draining step of draining the leafy vegetables salted in the salting step. A freezing step of rapidly freezing the leafy vegetables drained in the draining step. 2. The method according to claim 1, wherein at least one of an aqueous solution of a hypochlorite compound, an aqueous solution of chlorine dioxide, an aqueous solution of ozone, and an aqueous solution of a cationic or amphoteric surfactant is used in the washing step. How to freeze leafy vegetables. 3. The freezing temperature in the freezing step is -20.
The method for freezing leafy vegetables according to claim 1 or 2, wherein the temperature is in the range of -30 ° C to -60 ° C. 4. A pickle comprising, as a main material, a frozen leafy vegetable obtained by the method for freezing a leafy vegetable according to any one of claims 1 to 3.