JP2022144563A - Frozen vegetable and production method of processed vegetable - Google Patents

Abstract

[PROBLEMS] To provide a method for producing frozen vegetables and processed vegetables sanitarily enriched with γ-aminobutyric acid (GABA).
SOLUTION: A method for producing frozen vegetables characterized by enriching GABA contained in the vegetables by subjecting the vegetables having a water content of 70% by mass or more to a freezing treatment at a temperature of -20°C or lower. be. Further, the method for producing processed vegetables is characterized by subjecting the frozen vegetables obtained by this production method to a thawing treatment. By enriching GABA while rapidly cooling to a low temperature, hygienically enriched GABA-enriched frozen vegetables and processed vegetables can be obtained.
[Selection figure] None

Description

The present invention relates to a method for producing frozen vegetables and processed vegetables enriched with γ-aminobutyric acid.

γ-Aminobutyric acid (GABA) is one of naturally occurring amino acids, and is known to function as an inhibitory neurotransmitter and have bioregulatory functions such as suppression of blood pressure elevation and tranquilizing action. In order to efficiently ingest GABA, GA in foods such as vegetables that are eaten on a daily basis
Attempts have been made to enrich the BA content (eg Non-Patent Documents 1-2).

Hideki Horie and two others, “γ-Aminobutyric acid content in eggplant fruit and its increase due to heating,” Journal of Japan Society for Food Science and Technology, 2013, Vol.60, No.11, p. 661-664. Tadashi Takahashi and others, "Effect of low-temperature treatment on the components of Japanese yam (2nd report)", Proceedings of the 2017 Annual Conference of the Japan Society of Refrigerating and Air Conditioning Engineers, Japan Society of Refrigerating and Air Conditioning Engineers, 2017, D112 (in CD-ROM) .

In the techniques described in Non-Patent Documents 1 and 2, vegetables are kept at a temperature of about -10 to 40°C for a long time, and glutamic acid in vegetables is converted to GABA by the enzymatic action of glutamic acid decarboxylase (GAD) contained in vegetables. to enrich GABA in vegetables. As a result, it is possible to obtain processed vegetables that allow ingestion of a large amount of GABA and have excellent bioregulatory functions.

However, in the conventional technology, GABA is enriched by keeping vegetables in a temperature range where microorganisms propagate, so there is a sanitary risk such as putrefaction. Therefore, the present invention hygienically
An object of the present invention is to provide a production method capable of producing A-enriched frozen vegetables and processed vegetables.

As a result of intensive research and development in order to solve the above problems, the present inventors found that when GABA is enriched at a temperature lower than conventionally practiced, the amount of GABA produced greatly affects the water content of vegetables as raw materials. The inventors have found that this is acceptable, and proceeded with further development, leading to the completion of the present invention.
That is, the above problems are solved by the invention having the following configuration.

[1] A method for producing frozen vegetables, which comprises enriching GABA contained in vegetables by subjecting vegetables having a water content of 70% by mass or more to freezing treatment at a temperature of −20° C. or lower.
[2] The method for producing frozen vegetables according to [1], wherein the freezing treatment is rapid freezing treatment.
[3] The method for producing frozen vegetables according to any one of [1] or [2], wherein the vegetables are fruit vegetables, root vegetables or leafy stem vegetables.
[4] A method for producing processed vegetables, characterized in that the frozen vegetables obtained by the production method according to any one of [1] to [3] are thawed.

The production method of the present invention enriches GABA while keeping vegetables as raw materials at a low temperature of −20° C. or lower, where there is no risk of microbial growth. By this production method, hygienic GABA-enriched frozen vegetables and processed vegetables can be obtained without the risk of microbial growth.

In the method for producing frozen vegetables of the present invention, vegetables with a water content of 70% by mass or more are subjected to a freezing treatment at a temperature of -20°C or lower to obtain frozen vegetables enriched with GABA contained in the vegetables. It is. Further, in the method for producing processed vegetables of the present invention, the frozen vegetables obtained above are thawed to obtain processed vegetables.
The details of the present invention are described below.

First, vegetables used as raw materials in the present invention are vegetables with a water content of 70% by mass or more.
Vegetables such as fruit vegetables, root vegetables, and leafy stem vegetables can be preferably used. Root vegetables include carrots, burdock, Japanese radish, potatoes, and turnips; leafy and stem vegetables include cabbage, Chinese cabbage, celery, asparagus, green onions, garlic, and broccoli;
Green soybeans, fava beans, green peas, snow peas, green beans, pumpkins, corn, eggplants, green peppers, green peppers, okra, and the like. The term "vegetables" refers to the edible parts of the vegetable, mainly root and tuber root vegetables, leaf and stem vegetables, and fruits and seeds of fruit vegetables.
Use vegetables that have not undergone enzyme deactivation treatment. Enzyme deactivation treatment is a treatment to deactivate glutamic acid decarboxylase contained in vegetables by, for example, heat-treating vegetables with hot water or steam. Vegetables subjected to such treatment are not suitable as they do not produce GABA.

The moisture content of vegetables should be 70% by mass or more. The water content of vegetables may be controlled by making the vegetables absorb water. As for the water absorption method, methods such as immersion in water and exposure to a high-humidity environment can be used. Vegetables containing a moisture content of 70% by mass or more at the time of harvest may be used as they are, but as shown in the examples below, 80% by mass or more is preferable because the amount of GABA produced increases, and the desired GABA The amount of water may be adjusted according to the production amount.

Next, the vegetables with a moisture content of 70% by mass or more are subjected to freezing treatment at a temperature of -20°C or lower to obtain frozen vegetables. From the start of cooling until the vegetable temperature reaches the cooling temperature and freezes,
GABA is produced from glutamic acid by the enzymatic action of glutamic acid decarboxylase contained in vegetables, and as a result, frozen vegetables enriched with GABA are obtained.

The temperature for the freezing treatment is not particularly limited as long as it is −20° C. or lower, and may be appropriately selected according to the capacity of the refrigerating apparatus to be used. As the freezing treatment method, various methods such as a normal freezer (air blast method) that freezes using air as a refrigerant, and a quick freezing treatment such as liquid freezing can be adopted. In particular, when quick freezing is used, the temperature is lowered in a short period of time, so that the hygienic risk due to microbial growth can be further reduced. In addition, since cell destruction of vegetables can be further suppressed during freezing, deterioration of texture can be suppressed. When the quick freezing process is performed, it is preferable to perform the freezing process so that the temperature of the vegetables is lowered to -5°C or less within 30 minutes, and a quick freezing process such as liquid freezing can be preferably used.

In addition, it is preferable to keep the vegetables under anaerobic conditions when performing the cooling treatment. This is G
This is because the enzymatic action of AD is exhibited more strongly under anaerobic conditions. In order to freeze vegetables under anaerobic conditions, for example, the inside of a freezer may be replaced with an inert gas during cooling, or the vegetables may be degassed or packaged with an inert gas.

The obtained frozen vegetables are hygienic because they are enriched with GABA while being frozen at a low temperature of -20° C. or less without the risk of microbial growth. Therefore, the frozen vegetables can be easily kept at a low temperature and distributed as a frozen food with high preservability. In addition, since the obtained frozen vegetables are quickly frozen so as to suppress the cell destruction of the vegetables, deterioration in quality such as texture (hardness, shape, etc.) is suppressed, and the texture is excellent even after thawing.

The obtained frozen vegetables may be thawed and used as GABA-enriched processed vegetables. Any thawing method can be used according to the cooking method. For example, in order to enjoy a texture close to that of the original vegetables, it is preferable to defrost them at a low temperature. Also, when cooking with heat, it may be thawed by boiling or high-temperature steam. By either method, it is possible to sanitarily savor processed vegetables enriched with GABA.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

First, frozen vegetables were prepared using cabbage as leafy and stem vegetables, radish and carrots as root vegetables, and edamame and corn as fruit vegetables. In the examples, unless otherwise specified, the vegetables used were commercial products that had not been subjected to heat treatment such as enzyme deactivation treatment after harvesting.

<Frozen vegetables using cabbage>
(Example 1-1)
After removing about 3 surface layers of the cabbage, cut out the lower half so as not to include the core part, cut it radially into 16 equal parts, collect a part for analysis, and degas packaging the rest (film thickness 0 .08
mm), and subjected to liquid freezing treatment by immersing it in an alcohol solution held at a liquid temperature of -20 ° C. for 7 days in a refrigerator (Hoshizaki Denki, HRF-150ZF3), and the frozen vegetables of Example 1-1. Obtained.
In addition, when cabbage is subjected to liquid freezing treatment under the above conditions, the product temperature drops to -5°C in about 10 minutes.
The temperature reached -10°C after 15 minutes and -20°C after 20 hours. The cooling rate is the same for the following examples using cabbage.

(Example 1-2)
The cabbage cut out in the same manner as in Example 1-1 is dried in a low temperature dryer (cool dry machine,
DV-5P) and dried for a total of 41 hours while continuously changing the temperature and holding time of the dryer from 25° C. for 20 hours, 30° C. for 20 hours, and 35° C. for 1 hour. After drying, a portion was sampled for analysis, degassed and packaged in the same manner as in Example 1-1, and subjected to liquid freezing treatment to obtain frozen vegetables of Example 1-2.

(Comparative Example 1-1)
Frozen vegetables of Comparative Example 1-1 were obtained in the same manner as in Example 1-2 except that the time of holding at 35 ° C. in Example 1-2 was changed to 32 hours and drying was performed for a total of 72 hours.

(Comparative Example 1-2)
The liquid freezing treatment in Example 1-2 was performed using a liquid freezer (Technican, S-220
W) was used to obtain frozen vegetables of Comparative Example 1-2 in the same manner as in Example 1-2, except that the vegetables were immersed in an alcohol solution maintained at -10°C.

<Frozen vegetables using radish>
(Example 2-1)
Frozen vegetables of Example 2-1 were obtained in the same manner as in Example 1-1, except that radish (tuberous root) was used as the vegetable and cut into a cylindrical shape with a diameter of 2 cm and a length of 4 cm as a sample. When the radish was liquid-frozen under these conditions, the product temperature dropped to -5°C or lower in about 10 minutes, reached -10°C in 15 minutes, and -20°C in 17 hours. The cooling rate is the same for the following examples using radish.

(Example 2-2)
After cutting the radish in the same manner as in Example 2-1, the radish was immersed in distilled water maintained at 5° C. for 24 hours. After immersion, wipe off the moisture adhering to the surface, take a part for analysis,
The frozen vegetables of Example 2-2 were obtained by carrying out deaeration packaging and liquid freezing treatment in the same manner as in Example 2-1.

(Comparative Example 2-1)
After drying the radish cut out in the same manner as in Example 2-1 for 72 hours in the same manner as in Comparative Example 1-1, it was degassed and packaged in the same manner as in Example 1-1 and subjected to liquid freezing treatment. -1 frozen vegetables were obtained.

(Comparative Example 2-2)
Frozen vegetables of Comparative Example 2-2 were obtained in the same manner as in Comparative Example 1-2, except that the radish cut out in the same manner as in Example 2-1 was used as the sample.

<Frozen vegetables using carrots>
(Example 3-1)
Degassed packaging and liquid freezing treatment were performed in the same manner as in Example 1-1 except that carrots were used as vegetables and were cut into cylinders with a diameter of 3 cm and a length of 5.5 cm to form samples. Got frozen vegetables. When carrots were subjected to liquid freezing under these conditions, the temperature of the carrots dropped to -5°C or lower in about 25 minutes, reached -10°C in 30 minutes, and -20°C in 13 hours. The cooling rate is the same for the following examples using carrots.

(Example 3-2)
Frozen vegetables of Example 3-2 were obtained in the same manner as in Example 2-2, except that the vegetables used in Example 2-2 were changed to carrots cut out in the same manner as in Example 3-1.

(Comparative Example 3-1)
Carrots cut out in the same manner as in Example 3-1 were dried for 72 hours in the same manner as in Comparative Example 1-1,
After deaeration packaging, liquid freezing treatment was performed to obtain frozen vegetables of Comparative Example 3-1.

(Comparative Example 3-2)
Frozen vegetables of Comparative Example 3-2 were obtained in the same manner as in Comparative Example 1-2, except that carrots cut out in the same manner as in Example 3-1 were used as samples.

<Frozen vegetables using edamame>
(Example 4)
Edamame (with pods) is rubbed with salt, washed with water, drained, and then partly collected for analysis, the rest is degassed and packaged (film thickness 0.08 mm), and the liquid temperature is measured in the same manner as in Example 1-1. The frozen vegetables of Example 4 were obtained by subjecting them to liquid freezing treatment by immersing them in an alcohol solution maintained at -20°C for 10 days.

(Comparative Example 4)
Frozen vegetables of Comparative Example 4 were obtained in the same manner as in Example 4, except that the edamame soybeans (with pods) in Example 4 were preliminarily boiled for 1 minute to inactivate the enzyme.

<Frozen vegetables using corn>
(Example 5)
Using corn as a vegetable, removing the bracts from the spikes to obtain a sample, degassing packaging and liquid freezing treatment in the same manner as in Example 1-1 except that the period of immersion in the alcohol solution was set to 15 days. 5 frozen vegetables were obtained.

<Water content and GABA content>
Next, the obtained frozen vegetables were thawed by immersing them in ice water while still in the degassed packaging, opened, and a part of the vegetables were collected to measure the water content and GABA content. In addition, edamame (Example 4, Comparative Example 4)
and corn (Example 5) were thawed by boiling for 6 minutes and 5 minutes, respectively, while still packaged. GAB after boiling under the same conditions for the sample before freezing
It used for the measurement of A content.
The water content and GABA content were measured by the following methods.

(Measurement of moisture content)
Moisture content was measured by a dry method. Freeze-dry the collected sample for 7 days (ULVAC,
DFM-10N-04), and the water content was calculated from the weight change before and after that. In addition, Example 4
, For Example 5 and Comparative Example 4, the value described in the Standard Tables of Food Composition in Japan 2020 Edition (8th Edition) (Ministry of Education, Culture, Sports, Science and Technology) was used as the water content.

(Measurement of GABA content)
GABA content was measured by amino acid analysis after pretreatment as follows.
Pretreatment (for cabbage, radish or carrot): 0.02N after crushing the sample
Hydrochloric acid was added and extraction was performed with shaking overnight while the temperature was kept at 5°C. Thereafter, the supernatant obtained by centrifugation was adjusted to a constant volume with 0.02N hydrochloric acid, filtered through a filter (0.2 μm, PTFE), and diluted appropriately to obtain a solution which was subjected to amino acid analysis.
Pretreatment (for edamame or corn): First, pods were removed from edamame, and grains were collected from corn as samples. After the sample was freeze-dried and pulverized, an 80% ethanol solution was added and extracted with shaking. After that, the supernatant after centrifugation was collected, and the centrifugal residue was subjected to the same extraction operation twice, combined with the previously collected supernatant to a constant volume, and filtered through a filter (0.2 μm, PTFE). The obtained filtrate was fractionated, the solvent was removed by drying under reduced pressure, and hydrochloric acid was added to dilute the filtrate to a final concentration of 0.02 N. The obtained solution was subjected to amino acid analysis.
Amino acid analysis: 10 μL of the analytical solution obtained by the above pretreatment is further diluted with 70 μL of borate buffer, 20 μL of AccQ-Tag ^™ Ultra reagent (Waters) is added, immediately stirred, and then at 55°C. Fluorescence derivatization of GABA by warming for 10 minutes,
Liquid chromatography (Waters, ACQUITY UPLC H-Class (
Separate quantification was performed using a detector: PDA/QDa)).

Table 1 shows the results of measuring the water content and the GABA content before freezing (immediately before degassing packaging) and after thawing the frozen vegetables of Examples and Comparative Examples. For Examples 4 and 5 and Comparative Example 4, the values are measured per unit weight of dry powder.
Table 1 also summarizes the items and freezing treatment temperature conditions. The GABA increase/decrease ratio in the table is a value represented by GABA content after thawing/GABA content before freezing. Since the GABA content of each sample before freezing also increases during the immediately preceding drying treatment, the effect of increasing GABA by freezing treatment was compared based on the GABA increase/decrease ratio.

Focusing on the relationship between the water content and the GABA increase/decrease ratio for the samples that were frozen at -20°C in Table 1, the GABA increase/decrease ratio was 1 when the water content was about 70% or more in any item.
It can be seen that the For example, Comparative Example 1-1 has a water content of 37.5% by mass and a GABA increase/decrease ratio of 1.00, so GABA does not increase at all due to the freezing treatment, but the water content of Example 1-2 is 73.4%. sample, the GABA increase/decrease ratio increased to 1.11. From this, if the water content of vegetables is about 70% or more, GAB will be effective when frozen at -20 ° C.
It can be seen that A is enriched.
Also, as seen in Examples 1-1, 2-1, 2-2, 3-1 and 3-2, when the water content of vegetables is about 80% or more, 2. High G of about 5 to 4.4
The ABA increase/decrease ratio is shown, and it can be seen that GABA can be further enriched.
In addition, the GABA content was not enriched in Comparative Example 4 in which the enzyme was deactivated.

Although the mechanism by which the GABA content is effectively enriched under the condition that the water content is 70% or more is not clear, it is speculated as follows. As the temperature of vegetables is lowered and the freezing of water progresses, glutamic acid and glutamic acid decarboxylase are concentrated by freeze concentration, and GABA
The enzymatic reaction that produces is more likely to occur. When the cooling progresses and the temperature of the vegetables reaches about -20°C, most of the moisture freezes, and the enzymatic reaction almost stops here. At this time, vegetables with a low moisture content will quickly drop to -20°C, so they will be frozen with almost no enzymatic reaction, and vegetables with a high moisture content will take a certain amount of time to drop to -20°C. It is thought that the enzymatic reaction proceeds in
At this time, it is considered that the water content of the vegetables is about 70% or more, in which the balance between the time required for the enzymatic reaction and the time until freezing is just right.

Next, the quality of the obtained frozen vegetables when thawed was confirmed. As a result, the samples (Comparative Example 1-2, Comparative Example 2-2 and Comparative Example 3-2) subjected to cooling treatment at -10 ° C. were partially GA
Although the BA content increased, clear softening was observed, and all were inferior in quality. On the other hand, in the examples (Examples 1-1 to 5) in which the freezing treatment was performed at -20 ° C., compared with the case of freezing at -10 ° C., changes from before processing such as softening were suppressed. It was superior to the above comparative examples in terms of hardness, shape, color, and the like.
In addition, although it was confirmed that the GABA content was enriched in Comparative Example 3-1,
Due to its low water content, it was extremely hard and completely unsuitable for eating.

As described above, according to the method for producing frozen vegetables and the method for producing processed vegetables of the present invention, -20
GABA-enriched frozen vegetables and processed vegetables can be obtained in a safe environment with no risk of microbial growth. These frozen vegetables are produced under conditions that suppress tissue destruction of the vegetables, and can be enjoyed as processed vegetables with excellent quality such as texture by defrosting them as they are by any method.

Claims (4)

A method for producing frozen vegetables, characterized by enriching γ-aminobutyric acid contained in vegetables by subjecting vegetables having a water content of 70% by mass or more to freezing treatment at a temperature of -20°C or lower. 2. The method for producing frozen vegetables according to claim 1, wherein the freezing process is quick freezing process. 3. The method for producing frozen vegetables according to claim 1, wherein the vegetables are fruit vegetables, root vegetables or leafy stem vegetables. A method for producing processed vegetables, characterized in that the frozen vegetables obtained by the production method according to any one of claims 1 to 3 are thawed.