JPH08140570A - Preparation of frozen vegetable - Google Patents

Abstract

PURPOSE: To prepare frozen vegetable giving a cooked food free from softening and boiling collapse after thawing and cooking and having excellent palatability. CONSTITUTION: A whole or roughly cut vegetable is subjected to the tissue strengthening treatment and frozen to prepare a frozen vegetable. This tissue strengthening treatment comprises a process containing the lst step to treat the vegetable at a high temperature and the 2nd step to heat the vegetable in a calcium-containing aqueous solution as essential steps or a process containing the above two steps and the 3rd step to treat the vegetable again at a high temperature. The vegetable is preferably potato. The calcium- containing aqueous solution is preferably an aqueous solution of calcium lactate. A whole or roughly cut vegetable can be frozen by this process without causing the browning of the vegetable, keeping good palatability and preventing the boiling collapse and softening in the thawing and cooking procedures. This process can provide a frozen vegetable for secondary processing, e.g. plain dishes such as boiled meat and potato, a frozen vegetable to be heated for a long period such as the ingredients for Japanese hotchpotch and a frozen vegetable for retort-cooking resistant to the boiling collapse and softening even under severe heating condition such as heating in a retort.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of frozen whole vegetables or large-sized cut vegetables, which are cooked foods having an excellent texture without softening or boiling after thawing and cooking. Regarding the method. The frozen vegetables of the present invention are used for secondary processing used for side dishes such as meat potatoes, for long-term heating for oden seeds, and for retort heating processing.

[0002]

2. Description of the Related Art Many frozen vegetable materials, particularly potatoes, carrots, etc., cannot soften their texture before being frozen because the tissues are softened during cooking. In addition, for this reason, when thawing, cooking, and heating, boiling and melting or collapse occur, resulting in a marked drop in commercial value. For example, potatoes that have not been subjected to a freezing treatment have a soft texture, but after being frozen and thawed, they have a rough texture and are easily crumbled. In addition, vegetables that can be put in oden etc. offered at restaurants and convenience stores are usually boiled for a long time, not to mention frozen products.
Even if cooked from a perishable product that takes time to prepare, it cannot be provided in sufficient quality because it is easily boiled down. Therefore, some kinds of frozen vegetables have not been manufactured, or even if they are manufactured, their size and use are limited, and there are many problems in terms of quality.

As a method for preventing the deterioration of the texture after freezing and thawing, a commonly used method is rapid freezing, or a method of surface-treating using an aqueous solution of an organic acid salt and freezing (Japanese Patent Laid-Open No. 3-32337). )and so on. However, when such a method is used, the effect can be seen with a small cut of about 1 cm square, but "round-cut vegetables" such as potatoes that are still round and carrots that are greatly cut are quickly frozen or surface-treated. The effect of is limited to the surface tissue, the inside is slowly frozen, the internal tissue is denatured, and the texture upon thawing is reduced. In addition, the tissue is softened, and it is boiled down by the heat at the time of thawing, and it is boiled and melted, so that the commercial value is remarkably reduced.

It is considered that the above problems can be solved by strengthening the vegetable tissue so as to cope with the physical changes during freeze-thawing. Regarding the method of strengthening the vegetable tissue, for strengthening the cell wall by binding the pectin substance as a skeleton-forming component of the plant and calcium salt (Food R
esarch 6,449,1941) and that addition of calcium is expected to have an effect on softening by freezing (Journal of the Food Industry Society of Japan 25,213,1978). Also, the action is to activate the pectinesterase possessed by the plant to promote demethylation of the pectic substance, and to bind with the divalent cation containing calcium in the tissue in which the free carboxyl group coexists and harden ( Food Technology, 15, 16
0,1961) has been reported. Further, without adding calcium from the outside, the tissue may be hardened by heating at a temperature of 60 ° C. to 70 ° C. for a maximum of 2 hours (J. AGR. FOOD CHEM., 20, 2, 2. Two
66, 1972).

A patent application utilizing the technology for strengthening these structures is characterized in that at least the surface temperature of the surface is preheated at 45 to 75 ° C. for 10 to 180 minutes with any of water, dilute acidic water and sugar solution. Method for preventing softening of vegetables and fruits (JP-A-54-107542), immersing vegetables in an aqueous calcium solution at a low temperature, and then raising the temperature of the aqueous solution in the range of 40 to 70 ° C. A method for preventing softening of vegetables, which is characterized by holding for a certain period of time (JP-A-60-23).
No. 7957), there is a vegetable collapse prevention method (Japanese Patent Laid-Open No. 3-285651) characterized in that the vegetables are added to a calcium salt aqueous solution and decompressed prior to boiling the vegetables.

However, these patent applications do not relate to the technology relating to frozen vegetables. Even if these techniques are applied to the production of frozen vegetables, the vegetables after cutting are liable to be browned by enzymes in the tissue, and if tissue strengthening treatment of vegetables is performed for a long time without any treatment, Browning occurs on the surface of the vegetables, and especially if buds and skins are slightly overgrown, particularly strong browning occurs on those areas. Further, if the strengthening treatment is performed up to the central portion of the tissue, a problem that the surface portion becomes excessively hard when compared with the internal hardness at the time of thawing occurs. Especially in the case of whole vegetables and vegetables that have been cut into large pieces, these problems become prominent, and the above-mentioned technology alone does not cause browning even after thawing, retains a good texture, and does not collapse during cooking during thawing. It is impossible to produce frozen vegetables that do not soften and do not soften.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a frozen product of vegetables in the size of whole or cut into a cooked food having an excellent texture without softening or boiling down after thawing and cooking. Is intended to be manufactured. The present invention is a frozen vegetable for secondary processing used for side dishes such as meat potatoes, frozen vegetables for long-term heating such as oden seeds, and retort heating processing that does not collapse or soften even under severe heating conditions such as retort heating. Intended for the production of frozen vegetables.

[0008]

The present invention is a method for producing a frozen vegetable characterized by subjecting a vegetable having a size as a whole or a large cut to a tissue strengthening treatment and then a freezing treatment. Is the way.

The tissue strengthening treatment requires a first step of treating vegetables at a high temperature and a second step of heat treatment in an aqueous solution containing calcium, and adds a third step of treating again at a high temperature if necessary. Done in process. That is,
The present invention, when freezing a whole or large cut size vegetables, the first step of treating the vegetables at a high temperature and the second step of heat treatment in an aqueous solution containing calcium, if necessary at a high temperature again. A method for producing frozen vegetables, characterized by performing a tissue strengthening treatment comprising a third step of treatment.

The vegetables to which the present invention is applicable may be any vegetables used for heat-processed foods such as prepared foods and oden seeds and retort heat-processed foods. Examples include potato, carrot, burdock, radish, sweet potato, pumpkin, cauliflower and broccoli. In the present invention, it is preferable that the vegetables have a size as a whole or in a large size. The present invention is a vegetable that is used as a whole or cut into large pieces, and has problems such as deterioration in texture that occurs when it is thawed, softening, and simmering. This is a particularly suitable method.

It is possible to obtain a wide variety of frozen vegetables for cooked foods by combining the types and sizes of the above-mentioned vegetables and the conditions for strengthening treatment of vegetable tissues described below. There are various laws. The tissue strengthening treatment of the present invention is a treatment performed under conditions capable of strengthening the vegetable tissue. That is, it is performed under the condition that a frozen product that is a whole or a large cut size does not soften or boil down after being thawed and cooked and has a texture that is excellent in texture after being thawed and cooked. Processing.

[0012] To further explain, depending on whether the final cooked food type is for secondary processing used for side dishes such as meat potatoes, for long-time heating for oden seeds, or for retort heating processing. , The type of vegetable, size, heating temperature, conditions such as time, how to combine the third step before freezing, etc., to adjust the vegetable tissue strengthening processing conditions, that is, the processing conditions of each step, Frozen vegetables, which are cooked foods with an excellent texture, can be produced without softening or boiling down after thawing and cooking.

In the first step, the vegetables are heated in hot water or steam so that the surface temperature is 90 to 100 ° C.
It is a step of processing for a minute. This treatment deactivates the enzyme that causes browning of the vegetable surface and prevents the browning of vegetables. Further, since the surface texture can be softened to some extent to enhance the permeability of calcium, it is possible to prevent only the surface of the vegetables from becoming hard by the second step. Furthermore, by exposing to high temperature, the temperature rise of the central portion of the vegetables can be accelerated and the subsequent heat treatment time can be shortened. Frozen vegetables of the desired quality cannot be produced even if the treatments of the second and subsequent steps are performed without performing the treatment of the first step.

The surface temperature can be measured by embedding a minute thermocouple in the surface, measuring the surface temperature, attaching a surface thermometer to the surface, removing the vegetables from the heating device, and immediately using infrared radiation thermometer and thermometer. There are a method of measuring with a graph and the like, a method of applying a pigment whose color changes with temperature to vegetables and measuring with a color change, and a method of estimating the surface temperature by measuring the temperature inside the vegetables. In addition, since the surface temperature rises rapidly to the ambient temperature after the heating is started, it is possible to control the first step by the ambient temperature.

The first step is similar to a normal blanching operation, except that the blanching is cooled immediately after heating, while the first step is required to maintain a heated state. ing. Further, this treatment corresponds to preheating in the treatment of the next second step, and is greatly different from the normal blanching treatment in that less heat is applied. Frozen vegetables that are prepared only by normal blanching treatment do not have a good texture, and both thawing and cooking and heating take time, and the processing time is longer than when using raw vegetables. It takes a long time.

Among the treatment conditions, the surface temperature of 90 ° C. or lower is not sufficient to obtain the effect, and the enzyme involved in browning, such as polyphenol oxidase, is not inactivated and browning occurs. In addition, if the heating time is 2 minutes or less, heat is not even transferred to a part within a few mm from the surface that influences browning, and sufficient change is not observed in the tissue, causing browning. On the other hand, if heated for more than 5 minutes, heat will be transferred to the inside and browning can be prevented, but the structure will change too much, making it impossible to strengthen the structure in the next second step, and heating after thawing will cause collapse of the texture. Will decrease.

The second step of the present invention is a step which is carried out by immediately transferring the vegetables treated in the first step into a heated calcium solution and holding the central temperature at 55 ° C to 75 ° C for 10 to 90 minutes. is there. As the central temperature, the temperature of the product temperature center, that is, the temperature of the part (of vegetables) having the slowest temperature change was measured.
By this treatment, the pectinesterase possessed by the plant is activated to promote the demethylation of the pectic substance, and the released carboxyl group can bind to calcium in the coexisting tissue to strengthen the tissue of vegetables. If this treatment is not carried out, for example, before freezing, it is simply heated sufficiently to an edible state and then frozen and thawed, that is, if only the third step in the present invention is performed, the tissue is extremely thawed. Only products that tend to soften and crumble can be obtained.

The calcium used in the second step of the present invention may be any of calcium lactate, calcium sulfate, calcium chloride, calcium acetate, calcium carbonate and the like as long as it is water-soluble and harmless to the human body, but the solubility and taste are From the viewpoint, calcium lactate is preferable. The calcium solution used is preferably heated to a temperature of 60 ° C to 75 ° C.

The calcium concentration and treatment time in the second step differ depending on the degree of heating required after thawing. In a preferred embodiment of the present invention, vegetables that have been round or cut into large pieces are heated in hot water or steam in the first step.
After heating the surface to ~ 100 ° C and holding for 2-5 minutes,
In the second step, the core temperature is 55 ° C in an aqueous solution containing calcium.
~ 75 ° C for 10 to 90 minutes, the central temperature is 85 ° C in the third step
It is a method for producing frozen vegetables in which multi-step heating and freezing are performed by such a combination, in which the material is frozen at −95 ° C. and then frozen and stored. Even if the vegetables are round or cut into large pieces, the texture after thawing can be retained and the softening by boiling can be prevented even during reheating for cooking.

The frozen vegetables which are the object of the present invention are, for example, frozen vegetables for secondary processing. In the case of a cooking material used for stews, curries, oden to be served immediately after cooking, meat potatoes, etc., that is, a secondary processing material, it is held at a predetermined temperature for 10 to 30 minutes with a calcium concentration of 6 to 16 mM. In the case of a material for secondary processing, it is important that the treatment of the second step is not performed excessively and the surface is not made too hard. That is,
In the first step of the present invention, vegetables are first subjected to a surface temperature of 90 to 10
After treatment at 0 ° C for 2-5 minutes, in the second step 6-16m
Central temperature 55 ° C to 75 in an aqueous solution containing calcium of M
It is a method for producing a frozen vegetable for secondary processing, which is a treatment at 10 ° C for 10 to 180 minutes, preferably 10 to 30 minutes, heating in the third step until the central portion reaches 85 ° C to 95 ° C, and then freezing.

The frozen vegetable which is the object of the present invention is a frozen vegetable for oden seeds which is provided in a state of being boiled for a long time at over-the-counter sales or specialty stores. When used for cooking such as oden for a long period of time, the calcium concentration is 6 to 16 mM.
Hold at a predetermined temperature for 0 to 50 minutes. That is, the present invention first treats vegetables in the first step at 90 to 100 ° C. for 2 to 5 minutes, and then in the second step in an aqueous solution containing 6 to 16 mM calcium at a central temperature of 55 to 75 ° C. for 20 to 50. It is a method for producing frozen vegetables that do not soften and soften even after being heated for a long time by ordinary heating and cooking processing such as oden, which is processed by heating for 3 minutes and heating in the third step so that the central temperature is 85 to 90 ° C and then frozen. .

The frozen vegetable which is the object of the present invention is, for example, a frozen vegetable for retort heating processing. To provide the ingredients for the retort food, the second step is a calcium concentration of 13-
The core temperature is maintained at a predetermined temperature for 30 to 90 minutes at 50 mM. It is important to increase the calcium concentration in the second step and increase the treatment time so that the retort can withstand the harsh heating. The third step can be omitted. In this case, the present invention is a method for producing frozen vegetables for retort heating processing, wherein the third step is omitted and frozen vegetables are processed. That is, according to the present invention, in the first step, vegetables are first treated at a surface temperature of 90 to 100 ° C. for 2 to 3 minutes, and then in the second step, an aqueous solution containing 13 to 50 mM calcium is used at 60 to 75 ° C. At a central temperature of 55 to 75 ° C and 30 to
This is a method for producing frozen vegetables which is not boiled down and softened even if it is heated in a retort for 90 minutes after it is frozen. The obtained frozen vegetables are optimal as a material for retort pouch foods.

If the concentration is lower than these conditions or for a short time, the tissue strengthening is not sufficient, the texture corresponding to the application cannot be obtained, and it is not possible to prevent simmering. Further, if the concentration is higher than this and the time is longer, the tissue becomes excessively hard and the texture and taste are not preferable.

The treatment in the third step is mainly carried out so that the heating before eating can be completed in a short time and the material can be used as a cooking material with an excellent texture. As mentioned above, it is not necessary to perform this step for cooking where heating for the purpose of sterilization for a long time at high temperature and high pressure such as retort heating is not necessary, but when using it for cooking ingredients etc., the third step The processing of becomes necessary. When this step is not performed, that is, when only the tissue strengthening treatment using calcium or the like is performed, that is, when the treatment of the second step in the present invention is performed, a streaky texture is given at the time of thawing and it is eliminated. In order to do so, heating for a longer period of time is required than usual cooking and heating (90 to 100 ° C. for 15 to 30 minutes). As for the actual processing conditions, if the heating is terminated when the central portion of the vegetables reaches 90 ° C., a desirable texture is obtained. If the heating is not sufficient, it takes a long time to cook after thawing and the texture becomes streaky and rough. In addition, if the heating time is too long, thawing and softening will occur during thawing.

In addition, the vegetables processed at the time of the third step are subjected to usual cooking (seasoning and heating) processing and frozen,
It is also possible to produce cooked frozen foods such as meat potatoes, curries, oden and stewed foods. In this case, the third step of the method for producing frozen vegetables of the present invention is the heating and cooking step.

As for the cooling method before freezing, if a vacuum cooler is used, the cooling can be carried out quickly, but the desired quality product can also be obtained by cooling in water, leaving it in the air or cooling it by blowing air. be able to. Freezing and storage are done using a normal blast freezer,
Other freezing treatments may be used. In any case, quick freezing gives better quality.

[0027]

EXAMPLES The present invention will be described with reference to examples. The invention is in no way limited by this example.

Example 1 (heating conditions in the first step and browning prevention effect) 10 per piece
A strip of 0 g of raw potato peeled and exposed was exposed to tap water as a whole for 30 minutes, and then heated to each surface temperature as the treatment of the first step and held for each hour. Then, as a treatment of the second step, the mixture was placed in a 16 mM calcium lactate solution at 70 ° C. and held for 30 minutes so that the central temperature was 55 ° C. to 70 ° C. Next, as the third stage treatment, the center temperature is set to 90 ° C. and the ambient temperature is set to about 95 ° C. for about 20 ° C.
It was heated for 1 minute, and then blown and frozen at -40 ° C.
After storing at -30 ° C for 1 week, it was thawed at 95 ° C for 30 minutes to obtain the results shown in Table 1. In addition, as a comparison, the same treatment was carried out for those without the first step and those with only the third step, and the results are shown in Table 1. The temperature was measured using a Yokogawa Denki Co., Ltd. (μR1000 type, K type thermocouple) temperature recorder. The surface temperature was measured by embedding a thermocouple in the vegetable surface portion, and the center temperature was measured at the product temperature center, that is, the temperature of the vegetable where the temperature change was the slowest.

[0029]

[Table 1]

Example 2 (Calcium concentration and retort resistance) 100 g per piece
The raw potatoes obtained by peeling off the buds were exposed to tap water as they were for 30 minutes, and then placed in hot water at 90 ° C. for 2 minutes as the first step. Then, as the second step, 7
The mixture was placed in a calcium lactate solution having a concentration of 0 ° C., treated for 60 minutes, cooled, and then frozen at −40 ° C. After storing at -30 ℃ for 1 week, add 200 ml of oden soup stock to 2 potatoes.
Put the pieces and convert the temperature of the center of the potato to 121 ° C and heat for 11 minutes (F ₀ = 11, 121 ° C 60 minutes)
The results shown in Table 2 were obtained by heating the retort so that

[0031]

[Table 2]

Example 3 100 g of raw potatoes, which had been peeled and sprouted, were exposed to tap water as a whole for 30 minutes, treated under the conditions shown in Table 3, frozen by blowing at -40 ° C, After storing at 30 ° C. for 30 days and thawing under each condition, the results shown in Table 4 were obtained.

[0033]

[Table 3]

[0034]

[Table 4]

Example 4 (Heating conditions and texture of the third step) 100 g of raw potatoes were peeled from each piece and exposed to tap water as they were for 30 minutes. The mixture was placed in hot water at 90 ° C. and treated for 2 minutes so that the temperature became 0 ° C. Then, as a second step, the mixture was placed in a 16 mM calcium lactate solution at 70 ° C. and held for 30 minutes so that the central part was at 55 ° C. to 70 ° C., and as a third step, in hot water at 95 to 100 ° C.
Each heating time shown in (4) was maintained and set as the indicated center temperature. Then, it was cooled, and after cooling, it was frozen at -40 ° C. -30 ° C
After being stored for 1 week at 95 ° C., it was heated in hot water at 95 ° C. for 30 minutes and evaluated, and the results shown in Table 5 were obtained.

[0036]

[Table 5]

Example 5 (Cooking Meat Potatoes with Frozen Potato Treated under Secondary Processing Conditions) Peel and peel the potatoes into four pieces,
Using the water-exposed material as a material, heat it in hot water at 90 ° C. for 2 minutes so that the surface temperature becomes 90 ° C. as a one-step treatment, and as a second step treatment in 6 mM calcium lactate at 70 ° C. 1 so that the central part is between 55 ℃ and 70 ℃
Hold for 5 minutes, center temperature is 90 ° C as the third treatment
Was heated at 95 ° C. for 20 minutes. Then, it cooled and frozen at -40 degreeC. Stored at -30 ° C for 1 week.

This frozen potato, onion, and beef were added to a pan at a ratio of 5: 3: 1 and fried, and soy sauce, mirin, sugar, and bonito concentrated extract were mixed at a ratio of 5: 2: 1: 0.1. In addition, meat potatoes were prepared for 25 minutes.

For comparison, (1) raw potatoes, (2) first stage only, (3) second stage only, (4) third stage only, and then frozen. (5) A meat jaguar was prepared in the same manner by using only the first-stage and second-stage treatments and then the frozen treatment as a material.
Upon evaluation, the results shown in Table 6 were obtained.

[0040]

[Table 6]

Further evaluation was carried out using a material which was frozen and stored at −20 ° C. for 3 months, and the same result was obtained. In addition, after performing the first and second-stage treatments, the same cooking operation was performed to prepare meat potatoes, which were frozen, thawed in hot water after frozen storage, and the meat potatoes cooked using raw potatoes were The texture was comparable to that of potatoes.

Example 6 (Cooking of Oden Using Frozen Potatoes Treated Under Long-Term Heating Conditions) After radish and potatoes were washed with water, peeled, and sprout removed, pieces were cut to about 50 to 100 g or left as a whole. In the first step, the surface temperature was 100 ° C. for 3 minutes, and in the second step, the central portion was kept at 55 ° C. to 70 ° C. for 40 minutes in an aqueous solution containing 16 mM calcium lactate at 70 ° C. Heated visually at 95 ° C. for 30 minutes. Then, it was frozen at -40 ° C. Put the ingredients frozen at -30 ℃ for 1 week in water, mirin, soy sauce, concentrated bonito extract, 90: 3: 0.5: 1 into Odenashi soup and put it in the frozen state together with other oden ingredients. It was boiled for 60 minutes while boiling. After that, the liquid temperature was raised to 90 ° C. and the mixture was boiled for 6 hours. For comparison, oden was similarly prepared and evaluated for (1) those subjected to only the first-stage treatment, (2) those subjected to only the second-stage treatment, and (3) those subjected to only the third-stage treatment. went. The results are shown in Table 7.

[0043]

[Table 7]

Example 7 Carrots were washed with water, peeled, cut into pieces each having a size of about 50 g, treated in the first step for 2 minutes so that the surface temperature was 90 ° C., and then in the second step, 16 mM calcium lactate. The core portion was kept at 55 ° C. to 70 ° C. for 30 minutes in an aqueous solution containing, and heated in the third stage until the central temperature reached 95 ° C., and then frozen at −40 ° C. The material stored frozen at -30 ° C for 1 week was thawed in slightly boiling water to prepare carrots for garnishing. For comparison, (1) only the first-stage treatment, (2) the second-stage treatment, and (3) the third-stage treatment were prepared and evaluated. Table 8 shows the results.

[0045]

[Table 8]

[0046]

INDUSTRIAL APPLICABILITY Frozen vegetables, which are cooked foods having an excellent texture without softening or boiling after being thawed and cooked, can be produced. It is possible to produce frozen vegetables that do not turn brown when they are whole vegetables or vegetables that are cut into large pieces, retain a good texture, and do not soften when cooked during thawing. Frozen vegetables for secondary processing used for side dishes such as meat potatoes, frozen vegetables for long-term heating such as oden seeds,
It is possible to provide frozen vegetables for retort heating processing that do not collapse or soften even under severe heating conditions such as retort heating.

[Procedure amendment]

[Submission date] July 10, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

If the surface temperature is lower than 90 ° C. among the treatment conditions, the effect is not sufficient, and the enzyme involved in browning, such as polyphenol oxidase, cannot be inactivated, and browning occurs. In addition, the heating time is not yet 2 minutes
When it is full , heat is not even transmitted to a part within a few mm from the surface that influences browning, and sufficient change is not seen in the tissue, causing browning. On the other hand, if heated for more than 5 minutes, heat will be transferred to the inside and browning can be prevented, but the structure will change too much, making it impossible to strengthen the structure in the next second step, and heating after thawing will cause collapse of the texture. Will decrease.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

The frozen vegetable which is the object of the present invention is, for example, a frozen vegetable for retort heating processing. To provide the ingredients for the retort food, the second step is a calcium concentration of 13-
The core temperature is maintained at a predetermined temperature for 30 to 90 minutes at 50 mM. It is important to increase the calcium concentration in the second step and increase the treatment time so that the retort can withstand the harsh heating. The third step can be omitted. In this case, the present invention is a method for producing frozen vegetables for retort heating processing, wherein the third step is omitted and frozen vegetables are processed. That is, according to the present invention, in the first step, vegetables are first treated at a surface temperature of 90 to 100 ° C. for 2 to 3 minutes, and then in the second step, an aqueous solution containing 13 to 50 mM calcium is used at 60 to 75 ° C. 30 at ( center temperature 55-75 ° C )
It is a method for producing a frozen vegetable which is not boiled down and softened even when heated in a retort which is processed by freezing for 90 minutes. The obtained frozen vegetables are optimal as a material for retort pouch foods.

Claims (5)

[Claims] 1. A method for producing frozen vegetables, which comprises subjecting vegetables having a size of a whole circle or a large cut size to a tissue strengthening treatment and then a freezing treatment. 2. The frozen vegetable according to claim 1, wherein the tissue strengthening treatment is carried out in a step in which a first step of treating vegetables at a high temperature and a second step of heat treatment in an aqueous solution containing calcium are essential. Production method. 3. The tissue strengthening treatment requires at least a first step of treating vegetables at a high temperature, a second step of heat treating in an aqueous solution containing calcium, and a third step of treating again at a high temperature. The method for producing frozen vegetables according to claim 1, which is carried out in a step. 4. The vegetables according to claim 1, 2 or 3.
Alternatively, the method for producing frozen vegetables according to 3). 5. The method for producing frozen vegetables according to claim 1, wherein the aqueous solution containing calcium is an aqueous solution in which calcium lactate is dissolved.