JP2000308456A - Treating liquid before freezing for vegetable, treatment before freezing, vegetable treated before freezing and the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject treating agent capable of reproducing the fresh flavor of vegetables and further the flavor well after cooking, after thawing and also suitable for a thaw-drying by preparing an aqueous solution with adding a sugar and a sugar alcohol and adjusting the concentrations in specific ranges. SOLUTION: This treating liquid is prepared by adding a sugar and a sugar alcohol for obtaining an aqueous solution of which concentration is adjusted as 10-60 Brix %. In this case, it is preferable to add 100-200 ppm hypochloric acid in the treating liquid before freezing. Also, as the treatment before freezing of the vegetables, it is preferable to immerse the vegetables in the treating liquid before freezing for a prescribed period of time, and further, the vegetables are allowed to be fragile vegetables.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pre-freezing solution, a pre-freezing method and a pre-freezing method for vegetables, which can be excellently frozen even by a general freezing apparatus and are suitable for freeze-drying. Related to processed vegetables.

[0002]

2. Description of the Related Art Conventionally, vegetables have been stored for a long period of time by hot air drying, high pressure heating (retort treatment) or freezing. However, there is a problem that many of the characteristics of the fish disappear.

[0003] On the other hand, in the case of freezing storage in which the water content of vegetables is frozen at a temperature below the freezing point and stored for a long time, the vegetables are frozen after a predetermined pretreatment such as blanching with boiling water for a short time. However, since there is no need to perform heating other than blanching, there is no problem in hot air drying or high pressure heating. However, the cell structure of vegetables is destroyed by the ice crystals generated during freezing, and a large amount of drip flows out during thawing, and the texture (texture) after thawing is completely different from the texture of the original vegetables. Problem. Furthermore, the components undergo chemical changes due to changes in the hydrogen ion concentration (pH) due to changes in the water concentration due to the formation of ice crystals, enzymatic reactions, and the like. There is also the problem of being different. These problems in vegetables are remarkable as compared with animal meat and fish meat, making it difficult to freeze preserve vegetables.

[0004] In order to solve the problem caused by the cryopreservation,
1) Japanese Patent Application No. 58-54796 (JP-A-59-17903)
No. 1) discloses that ingredients such as vegetables and seafood are
A “frozen tool manufacturing method” has been proposed in which surface dehydration is performed in heating oil at 70 ° C. and then quick freezing is performed using, for example, liquid nitrogen. 2) Japanese Patent Application No. 59-99286 (Japanese Unexamined Patent Application Publication No.
Japanese Patent Application Laid-Open No. 0-241875) discloses a method of preparing fresh foods such as fish, shellfish, vegetables and fruits or processed products thereof by using a. Potassium chloride, b. Ethanol, and c. Sorbitol or glycerin or a mixture thereof. The present invention proposes a "method of preserving fresh foods or processed products thereof at low temperatures", which is characterized by preserving the fresh foods or processed foods by immersing them in a solution prepared by adding or pretreating by adding a solution and storing them by freezing or freezing. Similarly, 3) Japanese Patent Application No. 60-1
No. 03842 (Japanese Patent Application Laid-Open No. 61-265078) discloses that a hydrolyzate obtained by decomposing starch into a seasoning-containing liquid containing a predetermined seasoning (soy sauce, miso, sugar, etc.) contains D.
E30 or less (Dextrose Equivalent) was added in an amount of 5% by mass or more, and the liquid and a predetermined amount of vegetables and meats to be frozen were put together in a plastic bag and mixed (pickled) ) After that, they have proposed a “frozen food manufacturing method” in which they are stored frozen. Further, 4) Japanese Patent Application No. 2-131169 (JP-A-4-2737).
No. 5) immerses vegetables in a solution containing at least one of sodium chloride and potassium chloride and ethanol, sorbite, alum, ferrous compound and ascorbic acid, and then heats the vegetables to 100 to 200 ° C. A method for producing frozen vegetables, which is characterized by blanching with frozen edible fat and then freezing.

[0005] However, in the 1) "Method of manufacturing a frozen tool",
Since vegetables are fried in oil, it is not possible to reproduce the raw flavor or the flavor immediately after blanching (by hot water) even after thawing. Therefore, the use is limited. Furthermore, there is a concern that the oil during storage may deteriorate or deteriorate. In 2), `` Low-temperature preservation method of fresh foods or processed products '', vegetables can be applied to pickles such as shallow pickles, but it is possible to reproduce the raw flavor after thawing and the flavor immediately after blanching. Not suitable for required vegetables. In addition, when the vegetables subjected to the treatment described in this publication are freeze-dried in a vacuum, the vegetables shrink and shrink, and there is a problem that the resilience is not good. Further, in the method of 3), “Frozen food production method”, the use is limited because the seasoning-containing liquid and the vegetables are mixed and frozen. Also, the raw flavor of vegetables or the flavor immediately after blanching cannot be reproduced after thawing. In addition, in the method 4) for producing frozen vegetables, vegetables are fried in oil, so there is the same problem as 1). Regarding the use, in the “Effect of the Invention” part of the specification, “The frozen vegetable (according to the present invention) is suitable, for example, as a material for western food garni (garnish food) or Chinese food”. It indicates that it is suitable or unsuitable for the application. In addition, in the above-mentioned respective freezing methods (pre-freezing treatment), it is impossible to satisfactorily freeze soft vegetables such as bean sprouts and Chinese cabbage, which are particularly difficult to freeze. Similarly, freezing boiled thick radish and bamboo shoots (boiled vegetables), such as bath radish,
It is extremely difficult to freeze well, such as when the tissue becomes spongy.

On the other hand, as a long-term storage method of vegetables other than the above, after freezing vegetables, drying is performed by sublimating ice under vacuum for about 10 to 20 hours while keeping the frozen state. There is vacuum freeze drying (hereinafter referred to as “freeze drying”). This freeze-drying is widely used today because it has many excellent points that are not found in other storage methods, such as good flavor, beautiful appearance, and storage at room temperature.

[0007] However, in addition to the above-mentioned deterioration in quality due to freezing, the freeze-drying has a problem that vegetables shrink during drying and the outer shape cannot be maintained well. There is a problem not to do.
Further, there is a problem that during long-time drying, particularly in the latter half of the drying, a Maillard reaction occurs between the sugar and the amino acid, and the color is browned. These issues are the same as for cryopreservation
Notable for soft vegetables such as bean sprouts and Chinese cabbage. In addition, freeze-drying requires a lot of energy to perform drying over a long period of time, and the product price is somewhat higher than other storage methods. However, there is also a problem that consumers feel that the price of freeze-dried products is higher than it actually is. That is, the price of the freeze-dried product is also displayed based on the product mass (the amount of dry quality), so that the consumer recognizes the price by the unit price per product mass. On the other hand, the freeze-dried product has reduced the mass after drying to about one-twentieth of the mass before drying. Therefore, if the price is calculated per product mass, which is a dry base, for example, one gram of trefoil costs 130 yen, and the negative image that the freeze-dried product is extremely expensive is planted more than necessary. I have.

[0008]

As described above, the conventional freezing pretreatment has a problem that the raw flavor of vegetables and the flavor immediately after blanching cannot be reproduced even after thawing. In addition, freeze-drying has problems in terms of quality such as shrinkage during drying and Maillard reaction, and in terms of the image that the price is high due to a large decrease in mass. Furthermore, vegetables may have Escherichia coli attached to them, and this Escherichia coli may not be able to be killed by commonly used short-time blanching.

[0009] From the above problems, the present invention can reproduce the raw flavor of vegetables, the flavor immediately after blanching, and the flavor after cooking, even after thawing, and is also suitable for freeze-drying. An object of the present invention is to provide a pre-freezing solution, a pre-freezing method for vegetables, a pre-freeze-processed vegetable, and the like.

[0010]

The pretreatment solution for freezing vegetables according to the present invention, which has solved the above problems, has a Brix concentration of 10 to 60% by adding sugar and sugar alcohol.
(Claim 1). Since the pretreatment for freezing has a high osmotic pressure, the concentration of the intracellular solution of the vegetables is increased, and the pretreatment liquid itself also penetrates into the vegetables to lower the eutectic point of the vegetables. In addition, the solid sugar becomes a skeleton when dried,
Maintains shape and prevents extreme mass loss.

Further, the present invention relates to a method for preparing hypochlorous acid from 100 to 2 hours.
The freezing pretreatment liquid according to claim 1, characterized by adding 00 ppm. According to this, E. coli can be killed even with a relatively low concentration of hypochlorous acid in combination with a high concentration of sugar in the pretreatment for freezing.

According to a third aspect of the present invention, there is provided a pre-freezing method according to the present invention, wherein vegetables are immersed in the pre-freezing solution according to the first or second aspect for a predetermined time. According to this, the pre-freezing liquid permeates moderately into the vegetables to be frozen.

Further, the present invention proposes a method for pre-freezing vegetables according to claim 3, wherein the vegetables to be frozen are soft vegetables (claim 4). According to this method, it is possible to perform a favorable freezing process and a subsequent freeze-drying process even on a soft vegetable that is extremely difficult to freeze.
In addition, soft vegetables include bean sprouts, Chinese cabbage, bok choy, three leaves, onions, kyona, komatsuna, udo, nozawana, myoga,
Vegetables with remarkable tissue destruction caused by freezing of cracked radish, radish, etc., and having difficulty in reproducing the raw flavor / texture after thawing or the flavor / texture immediately after blanching. Soft vegetables also include root vegetables such as radish, turnip, carrot, burdock, and bamboo shoots that are cooked as thick-cut vegetables. Even in the case of thick-cut vegetables, the pre-freezing solution penetrates into the inside and suppresses tissue destruction due to growth of ice crystals during freezing.

Further, the present invention relates to claim 3 or claim 4.
(4) A pre-frozen vegetable obtained by the method for pre-freezing vegetables described in (1). The pre-freezing treatment according to the present invention is durable, and it is possible to put the pre-frozen treated vegetables in the distribution process.

Further, the present invention is a frozen vegetable obtained by freezing the frozen pretreated vegetable according to claim 5 (claim 6), and the frozen pretreated vegetable according to claim 5 or Dried vegetables obtained by freeze-drying the frozen vegetables according to claim 6 (claim 7). According to this, the components in the pre-freezing solution have penetrated moderately into the vegetables,
Ice crystal formation in the maximum ice crystal formation zone is suppressed, and tissue destruction during freezing is reduced. In addition, since the components in the pretreatment for freezing become skeletons during freeze-drying, deformation during drying and extreme decrease in mass are suppressed.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a process diagram of freeze-drying including pre-freezing treatment according to the present invention.

<< Description of Pretreatment for Freezing >> The freezing treatment according to the present invention comprises an aqueous solution whose concentration is adjusted to 10 to 60 Brix% by adding sugar and sugar alcohol.

As the sugar, one or more sugars selected from the group consisting of lactose (lactose), maltose (maltose), sucrose (sucrose) and the like are used. Sugar is added for the purpose of lowering the eutectic point of vegetables to prevent the occurrence of tissue damage or the like due to freezing. Among them, lactose and the like do not have a strong sweetness, so that the processed vegetables do not become sweet, and are suitable for use of the pretreatment solution for freezing of the present invention.

Examples of the sugar alcohols (hexitol [hexit]) include sorbitol (D-sorbit), mannose (D-mannitol), idose (D-indit), talose (D-talit), dursit (D-galactose), One or more sugar alcohols selected from the group consisting of alit (D-allose) and the like are used. Sugar alcohol has the effect of lowering the eutectic point of vegetables, similar to the sugars described above, but has another significant effect of giving vegetables more flexibility. Of these, sorbitol is suitable because it is particularly excellent in water retention,
There is no problem even with mannose or idose.

The concentration of the pre-freezing solution is adjusted by adding sugar and sugar alcohol so that the concentration becomes 10 to 60 Brix%. Concentration is 10 Brix%
In the following, sufficient pre-freezing treatment cannot be performed even for a long time. On the other hand, when the concentration is 60 Brix% or more, the difference in osmotic pressure between the vegetables and the pre-freezing solution becomes too large, and the vegetables are dehydrated as if being pickled, and become wilted. It is not preferable in respect of the point. In addition, the sugar does not dissolve sufficiently. Further, when the concentration is high, the surface of the vegetables becomes white due to crystals of sugars such as lactose when freeze-drying is performed, and the vegetables adhere to each other, which is not preferable.

The concentration is 20 to 50 Brix%.
Is more preferable, and still more preferably 30 to 50 Brix%. If the pre-freezing solution is within this concentration range, the desired pre-freezing treatment can be reliably performed in a short time, and thereby, frozen vegetables and dried vegetables of excellent quality can be obtained. The larger the value, the shorter the processing time). When the concentration is 20 Brix% or less,
Although the processing time is prolonged, if the concentration is 10 Brix% or more, the pretreatment for freezing can be reliably performed by setting the processing time longer.

The sugar is 7-55 Brix%, preferably 15-55 Brix%, more preferably 25-4 Brix.
It is added in the range of 5 Brix%. If the sugar concentration is too low, sufficient pretreatment for freezing cannot be performed even if it takes time, and if it is too high, vegetables will be dehydrated.
On the other hand, the sugar alcohol is added within a range of 1 to 10 Brix%, preferably 3 to 7 Brix%. If the concentration of the sugar alcohol is too low, the vegetables will not be supple, while if the concentration is too high, the vegetables will be too sweet.

The sugar and sugar alcohol (hereinafter referred to as "sugar etc.")
) Penetrates into the tissue of the vegetable to lower the eutectic point of the liquid present in the tissue of the vegetable, thereby inhibiting the growth of ice crystals and forming ice crystals. Fine, no tissue damage due to freezing. In terms of phenomena, it is the largest ice crystal formation zone.
The rate of ice crystal formation at 1 ° C. to −5 ° C. decreases, and the plateau (flat portion appearing at −1 ° C. to −5 ° C.) in the freezing curve of the product temperature and the freezing time becomes unclear. In addition, at the time of thawing, in addition to the protection of the tissue of vegetables from damage due to the formation of ice crystals, the production of drip is further suppressed because sugar and the like have good water retention. Furthermore, the chemical reaction by the enzyme is also suppressed. In addition, since the formation of ice crystals is suppressed due to a drop in the eutectic point or the like, thawing can be performed relatively quickly. Therefore, according to the pre-freezing solution of the present invention, excellent freezing of vegetables can be performed.

On the other hand, at the time of freeze-drying, sugar or the like plays a role of a shape-retaining material, and shrinkage during drying is suppressed. In addition, sugars and the like prevent excessive drying of vegetables, so that the mass of the freeze-dried product does not significantly decrease (even if moisture remains to some extent, the moisture does not adversely affect the quality). Therefore, when the unit price of the freeze-dried product per mass is calculated, the price can be reduced to 1/2 to 3/4 as compared with the conventional freeze-dried product. Therefore, it is possible to improve the negative image based on the conventional preconception that the freeze-dried product is extremely expensive, and there is an advantage that the use of the freeze-dried product is expanded. In addition, the amount of water to be sublimated is reduced,
There is an advantage that the drying time is shortened and the energy required for drying can be reduced. Furthermore, the shortening of the drying time reduces the time of exposure to high temperatures, especially at the end of drying, so that the Maillard reaction, which tends to occur during this time, can be suppressed, and the browning of the product can be effectively suppressed. There is also a big benefit of being able to do it.

The pretreatment solution for freezing according to the present invention is added with 100 to 200 ppm of hypochlorous acid, if necessary. In some cases, Escherichia coli is sterilized by adding a small amount of hypochlorous acid thereto. This sterilization of Escherichia coli cannot be performed sufficiently when the concentration of hypochlorous acid is 100 ppm or less, and when it is 200 ppm or more, there is a problem that chlorine odor is transferred to vegetables. Therefore, the concentration of hypochlorous acid in the pretreatment for freezing is 100 to 200 pp.
m is suitable.

By the way, when sprouts were immersed in the pre-freezing solution without addition of hypochlorous acid for 3 hours, the coliform group (E. coli) was positive.
When sprouts were immersed for 1 hour after adding 50 ppm of hypochlorous acid, the coliform group (E. coli) was negative. At this time, the number of general viable bacteria was within 1000 / g. These results are data obtained when blanching for 30 seconds is performed before the freezing pretreatment step. To sterilize coliform bacteria using only hypochlorous acid, 2
A hypochlorous acid concentration of 50 to 500 ppm is required, but in an aqueous solution of a high-concentration sugar or the like, even a low-concentration hypochlorous acid can surely sterilize coliform bacteria.

Salt may be added to the pre-freezing solution as needed. This is because the addition of salt improves the taste of vegetables. Another advantage is that the restoration speed is increased. The amount of salt added is preferably 1 to 7% by mass based on the pretreatment solution for freezing. If the amount is less than 1% by mass, there is no effect of adding salt, and if the amount is more than 7% by mass, the vegetables become salty, though depending on the use of the vegetables.

<< Description of Pre-freezing Method >> The pre-freezing method of the present invention will be described with reference to the process chart shown in FIG. The pre-freezing treatment of the present invention is usually performed after a blanching step.

1) (Pre-processing; S1) Vegetables are washed with water,
Pre-processing such as draining and, if necessary, cutting to an appropriate size is performed. Further, a sterilization step using an aqueous solution of hypochlorous acid or the like may be provided during this pre-processing step.

2) (Blanching; S2) Blanching is carried out in the same manner as ordinary blanching by putting vegetables washed in hot water at 90 to 100 ° C. Blanching deactivates enzymes that are active at low temperatures. Blanching is performed for tens of seconds to several minutes. Note that vegetables used as boiled vegetables are heated to the core as needed. In addition, for items that require drilling, such as bamboo shoots, drilling is performed in this step.

3) (Pre-cooling; S3) Pre-cooling is performed to remove rough heat immediately after blanching, thereby preventing excessive blanching. The pre-cooling may be performed by immersing the vegetables in water or by blowing clean air on the vegetables. Note that this pre-cooling can be omitted, and in some cases, the pre-cooling may not be performed after the blanching, and the process may proceed to the next freezing pre-treatment step.

4) (Pre-freezing treatment; S4) Vegetables that have been subjected to blanching and, if necessary, pre-cooling are immersed in the above-mentioned pre-freezing treatment liquid. The immersion time varies depending on the concentration of the pre-freezing solution, the type of vegetables, and the cutting conditions, but is 20 minutes for the early one and 5 hours for the late one. Although the water temperature is not particularly limited, it is not necessary to particularly heat or cool. Regarding the immersion time, if this time is short, sugar or the like does not sufficiently penetrate into the tissue of the vegetable, causing tissue damage during freezing. On the other hand, when immersed for a long time, there arises a problem that vegetables are withered. The time required for immersion is the case of uncut vegetables. For example, bean sprouts and the like require a relatively long time (about one hour or more) because cutting processing is not usually performed. On the other hand, in the case of finely cut vegetables, it can be processed in a relatively short time (20 minutes to 1 hour). Care must be taken when immersing cut vegetables as they tend to wither. By the way, when hypochlorous acid is added to the pre-freezing solution, it is preferable to perform the immersion for one hour or more. This is because sterilization of the coliform group is ensured.

When the vegetables are pre-cooled by immersing them in water or the like, it is preferable to sufficiently drain the vegetables by, for example, a centrifugal dehydrator. This is for preventing a decrease in the concentration of the pretreatment solution for freezing due to excess water attached to vegetables. Further, if the vegetables are drained (dehydrated) to a state where the water content is slightly insufficient, the vegetables can be encouraged to absorb the freezing pretreatment liquid. On the other hand, when pre-cooling is performed using clean air, there is an advantage that excess moisture is removed during pre-cooling. Thus, the pre-freezing treatment time can be reduced. During immersion in the pretreatment for freezing, it is preferable to occasionally agitate the whole. This is because the concentration of the pretreatment for freezing in the portion that is in contact with the vegetables is reduced by the water that has permeated from the vegetables.

5) (Washing; S5) After immersing in the pre-freezing solution for a predetermined time, the vegetables are taken out and washed with water. This is to stop the pre-freezing process. Vegetables washed with water are sufficiently drained by a centrifugal dehydrator as needed. By performing the draining sufficiently, the vegetables can be frozen more quickly than when the drainage is not performed. This is because excess water attached to vegetables causes a large thermal load when the vegetables are frozen. The vegetables that have been pre-frozen may be shipped as commodities (such as cut vegetables suitable for the manufacture of frozen foods) after the washing (draining as necessary) is completed (S5-a, b). This is because the pre-freezing treatment according to the present invention is persistent.

6) (Frozen; S6) After washing with water (preferably washing and draining), the vegetables are divided into appropriate amounts and shapes (they may be separated and then dewatered) and frozen in a freezer. Do. The freezer may be a natural convection type, a forced convection type, or a contact type, and the freezing method is not particularly limited. This is because sugars and the like have penetrated into the vegetables to be frozen, so that tissue destruction can be avoided even without quick freezing. The vegetables that have been frozen may be packed at this stage and shipped as commodities (S6-a, b). In the freezing, self-freezing may be performed by the force of a vacuum in the next freeze-drying. In this case, the above-mentioned freezer is not required.

7) (Freeze-drying; S7) Freeze-drying is performed according to a normal process. However, since sugar and the like have penetrated into the vegetable tissue by pre-freezing treatment, the amount of water to be removed is determined according to the present invention. Significantly less than vegetables without pre-freezing treatment.

For example, when the pre-freezing treatment according to the present invention was not performed, the mass before drying was 10 kg, but after drying the mass was reduced to 0.5 to 0.7 kg (yield 5 to 0.7 kg). 7%). On the other hand, when the freezing treatment according to the present invention was performed, the mass before drying was 10 kg, but the mass after drying was 2-3 kg (yield 20
３０30%). That is, the amount of water to be removed is clearly smaller when the pre-freezing treatment is performed. This allows
It is possible to significantly improve product yield and reduce energy by shortening the drying time. Also, the reduction in the amount of water to be removed means that the load on the cold trap of the freeze dryer is reduced, and the amount of raw materials charged into the freeze dryer can be increased. Therefore,
The product cost can be significantly reduced, and the negative image of the consumer can be reduced.

Since the shortening of the drying time can reduce unnecessary heating of the already dried portion in the latter stage of the drying, it suppresses the browning due to the Maillard reaction and the decomposition and deterioration of heat-sensitive components. There are also quality benefits, such as being able to do so. In addition, shrinkage during drying is greatly suppressed due to the reduced amount of water to be removed and the presence of sugar, which is a solid content that has penetrated into the tissue. The dried freeze-dried product is packaged with a packaging material having gas barrier properties and shipped as a product (S7-a, b).

8) (Others) The freeze-dried product is water
It is reconstituted with warm water or hot water and eaten as it is or cooked. However, in addition to the absorption of water-absorbing (water-retentive) sugar inside the tissue due to pre-freezing, shrinkage during drying may occur. Because it is greatly suppressed, the tissue is well preserved and has very good resilience. Moreover, since the occurrence of tissue damage during freezing is suppressed, the texture of the freeze-dried vegetables immediately after blanching remains well. Furthermore, it also has flexibility. Also, when thawing is performed after freezing, the occurrence of dripping is small, and the texture immediately after blanching remains well.

[0040]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples. Note that, of the present embodiment, the first embodiment and the second embodiment
This is when freeze-drying was performed on vegetables that had been subjected to pre-freezing treatment.

(Example 1) Freeze-drying of bean sprouts The pretreatment for freezing in the present example was as follows.
The liter was adjusted. Solution A: Pre-freezing solution having a total concentration of 20 Brix% by adding sorbitol to a 17 Brix% lactose aqueous solution Solution B: Total concentration of 38 Brix by adding sorbitol to a 35 Brix% lactose aqueous solution Pre-freezing solution C which becomes a freezing pre-treatment solution whose total concentration becomes 50 Brix% by adding sorbitol to a 35 Brix% lactose aqueous solution

The sprouts (1 kg) are washed and drained →
Blanching (30 seconds in hot water at 95 ° C) →
Rinsing and draining → Pre-freezing treatment (immersed in the pre-freezing solution for 3 hours) → Rinsing and draining from the pre-freezing solution → Freezing (overnight in an atmosphere of -30 ° C) → Freeze-drying Was done. The draining was performed at 200 rpm for 15 seconds using a centrifugal dehydrator. The draining was performed at 600 rpm for 2 minutes using a centrifugal dehydrator.

The pre-freezing treatment was carried out by immersing bean sprouts in solution A for 3 hours (product treated with solution A), immersed in solution B for 3 hours (product treated with solution B), and immersed in solution C for 3 hours (C Liquid-treated product). The freeze-drying conditions were a pressure of 13.3 to 66.5 Pa (0.1 to 0.5 torr), a cold trap temperature of -45 ° C, and a drying time of 18 hours. As a target product, freeze-drying was also performed on the bean sprouts without the pre-freezing treatment according to the present invention. The target product was processed by the same process as the product of the present invention, except that the pre-freezing treatment was not performed. However, the amount of the target product charged to the freeze dryer was previously reduced so that the drying time of the target product was 18 hours.

[Results] The appearance (shape and color) of the freeze-dried bean sprouts subjected to the pre-freezing treatment according to the present invention is as follows:
All of the B-treated and C-treated products were good. On the other hand, the target product was brownish in color and shrunk in shape, and was in the form of a withered straw chip. The freeze-dried bean sprouts subjected to the pre-freezing treatment according to the present invention were successfully restored with hot water at 80 ° C. in about 2 minutes. All of the three pre-freezing treatments were able to satisfactorily reproduce the characteristic texture of the crisp bean sprouts immediately after blanching, but the B-liquid treated product and the C liquid-treated product were excellent. On the other hand, the target product did not sufficiently restore even with the lapse of time, and the texture was not able to reproduce the characteristic feeling of bean sprouts with a crisp texture at all.
Regarding the taste, the liquid C-treated product to which about 15 Brix% of sorbitol was added was sweetened due to the concentration thereof, but the liquid A-treated product and the liquid B-treated product had a good taste. On the other hand, the target product was unbearable to taste. Then, when these results were combined, the A liquid treated product and the B liquid treated product were excellent.

The frozen product was thawed with running water and eaten. Good results corresponding to the freeze-drying result were obtained. On the other hand, when the target product was thawed in the same manner, the tissue was remarkably destroyed, and was unbearable to taste.

(Example 2) Freeze-drying of Chinese cabbage The pretreatment for freezing in this example is the same as the solution A and B in Example 1.
Liquid and liquid C were used. Chinese cabbage (1 kg) was cut into a size of about 1 cm square. This was freeze-dried under the same steps and conditions as in Example 1. However, blanching was performed in hot water at 95 ° C. for 60 seconds. As a target product, Chinese cabbage without the pre-freezing treatment according to the present invention was also used in Example 1.
The freeze-drying was performed in the same manner as in the case of the target product.

[Results] The appearance (color and shape) of the freeze-dried Chinese cabbage subjected to the pre-freezing treatment according to the present invention was as follows:
The liquid-treated product and the C-liquid treated product were all good. on the other hand,
The target product was shrinking and deforming. In addition, the freeze-dried Chinese cabbage that has been subjected to the pre-freezing treatment according to the present invention can be well restored in about 2 to 3 minutes by hot water of 80 ° C., and reproduce the unique texture of the fresh Chinese cabbage immediately after blanching. However, the B-liquid treated product and the C-liquid treated product were excellent.
On the other hand, the target product did not fully restore over time, and the texture was completely different from that immediately after blanching.
Regarding the taste, the liquid C-treated product to which about 15 Brix% of sorbitol was added was sweetened due to the concentration thereof, but the liquid A-treated product and the liquid B-treated product had a good taste. On the other hand, as in the case of the sprouts of Example 1, the target product was unbearable to taste. And
Compiling the results, the A liquid treated product and the B liquid treated product were excellent.

The frozen Chinese cabbage was thawed with running water and eaten. As in the case of the bean sprouts in Example 1, good results corresponding to the results of the freeze-drying were obtained. On the other hand, when the target product was thawed in the same manner, the tissue was remarkably destroyed, and was unbearable to taste.

(Example 3) Freezing of thick-sliced radish The liquids A and B used in Examples 1 and 2 were used as the pretreatment for freezing in this example. The radish is peeled → cut (1 to 4 cm in thickness) → cut off (square) → blanching (30 to 1 hour and a half) →
Pretreatment for freezing (2 to 3 hours) → washing and draining after removal from the pretreatment for freezing → freezing (in a -30 ° C atmosphere overnight). here,
Blanching is 1 hour 2 when radish thickness is 4cm
It was cooked for about 0 minutes until the fire passed. This time is appropriately adjusted depending on the thickness of the material and the like.
In order to promote the pre-freezing treatment, the pre-freezing treatment was performed by placing the radish that had remained hot in the pre-freezing pre-treatment liquid. In addition,
As a target product, after blanching of radish not subjected to the pre-freezing treatment of the present invention, washing and draining were performed and frozen. These samples were subjected to natural thawing to measure the change in mass before and after thawing, etc., and thawed in a microwave oven for sensory evaluation.

[Results] The frozen radish (the solution treated with the solution A and the solution treated with the solution B) which had been subjected to the pre-freezing treatment according to the present invention was thawed, but the amount of drip was slight and the internal structure was good. It was also very organoleptically satisfactory. On the other hand, for products that are not subjected to pre-freezing treatment,
Dripping occurred remarkably, and the internal structure became porous like a sponge. And sensually,
In particular, the palatability was poor. In addition, the freeze-drying was performed on the A liquid-treated product according to the procedure of Example 1, and good drying was performed.

(Embodiment 4) Freezing of bamboo shoots The pretreatment for freezing in this embodiment is the same as the solution A and B in Example 3.
The liquid was used. Bamboo shoots are peeled → drilled / boiled → cut (3mm to 4cm thick) → pre-freezing (30
〜3 hours) → Washing and draining from the pre-freezing solution → freezing (overnight in an atmosphere of −30 ° C.). Here, the drilling and boiling were performed until the drilling was sufficiently removed. In addition, as a target product, bamboo shoots not subjected to the pre-freezing treatment of the present invention,
After the cut, water washing and draining were performed to freeze. These samples were subjected to natural thawing to measure the change in mass before and after thawing, etc., and were subjected to sensory evaluation by thawing in a microwave oven.

[Results] The frozen bamboo shoots (solution A treated and solution B treated) which had been subjected to the pre-freezing treatment according to the present invention were thawed.
The amount of drip was slight and the internal structure was good. It was also very organoleptically satisfactory.
On the other hand, with respect to the target product not subjected to the pre-freezing treatment, dripping occurred remarkably and the mouthfeel was inferior.

Example 5 10 Brix% Concentration A pre-freezing treatment was carried out with a pre-freezing solution having a total concentration of 10 Brix% by adding sorbitol to a 7 Brix% lactose aqueous solution. The processing procedure is based on the first to fourth embodiments. As a comparative example, a freezing treatment was performed in the same manner as in Example 5 with a pretreatment solution for freezing in which the total concentration was 5 brix% by adding sorbitol to a 4 brix% lactose aqueous solution. Table 1 shows the conditions of the freezing pretreatment and the results.

[0054]

[Table 1]

As shown in Table 1, in Example 5, both freezing and freeze-drying were successfully performed. On the other hand, in the comparative example, the pre-freezing treatment could not be sufficiently performed even when the immersion was performed over time. Therefore, loss and browning were conspicuous in freeze-drying. Thus, the concentration of the pre-freezing solution was 1
Good freezing pretreatment can be performed even at 0 Brix%.

(Others) In addition to the above examples, tests were conducted on various items such as matsutake mushrooms, shiitake mushrooms, eggplants, lotuses, capets, various root vegetables and pods. As a result, items that are considered difficult to freeze or freeze-dry can be satisfactorily frozen, while items that are considered to be one step more difficult to freeze or freeze-dry have the same quality as conventional products. Was significantly improved.

Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the means and methods described above, and achieves the object of the present invention and has the effects of the present invention. Changes can be made as appropriate within the scope.

[0058]

As described above, according to the pre-freezing treatment of the present invention, it is possible to perform freezing satisfactorily without destroying the vegetable tissue. In addition, even in the case of freeze-drying, the texture immediately after blanching could be sufficiently reproduced with respect to soft vegetables such as bean sprouts and Chinese cabbage which could not be dried at all in the past. Furthermore,
Good freezing and freeze-drying can also be performed on thick-sliced boiled vegetables and the like.

The amount of addition of hypochlorous acid was about half that in the case of sterilization using hypochlorous acid alone. Further, since the amount of hypochlorous acid added can be suppressed, no chlorine odor is left on vegetables.

[Brief description of the drawings]

FIG. 1 is a process diagram of freeze-drying including pre-freezing treatment according to the present invention.

Claims (7)

[Claims] 1. A pretreatment solution for freezing vegetables comprising an aqueous solution whose concentration is adjusted to 10 to 60% by brix by adding sugar and sugar alcohol. 2. The method according to claim 1, wherein the pretreatment for freezing comprises adding hypochlorous acid to the solution.
2. The composition according to claim 1, wherein the amount is from 0.00 to 200 ppm.
4. A pretreatment solution for freezing vegetables according to item 1. 3. A pre-freezing method for vegetables, comprising immersing vegetables in the pre-freezing solution according to claim 1 for a predetermined time. 4. The pre-freezing method for vegetables according to claim 3, wherein the vegetables are soft vegetables. 5. A pre-frozen vegetable obtained by the method for pre-freezing vegetables according to claim 3 or 4. 6. A frozen vegetable obtained by freezing the frozen pretreated vegetable according to claim 5. 7. Vegetables that have been pre-frozen according to claim 5 or dried vegetables obtained by freeze-drying the frozen vegetables according to claim 6.