JP5476143B2 - Frozen vegetables and processed foods suitable for microwave heating - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a frozen vegetable that is used in the manufacture of processed foods such as retort foods and the like and that does not easily collapse when heated by a microwave oven, and a processed food for microwave heating using the same.

  Processed foods such as retort foods and chilled foods are usually produced by cooking and sterilization (sterilization) by heat treatment in order to enable storage for a certain period of time at normal temperature, chilled, frozen, etc. As a raw material for such processed foods, it is generally performed to use frozen vegetables. The above processed food is also heated in a microwave oven.

  In the above-mentioned form, the applicant of the present invention is a processed food manufactured using a raw material containing frozen vegetables such as frozen potatoes, frozen root vegetables, etc., and for cooking / sterilization (sterilization). When the temperature of the heat treatment to be performed (retort sterilization treatment, etc.) is higher than a certain temperature, the processed food manufactured with the raw material that has not been frozen, or the heat treatment at a temperature lower than the aforementioned certain temperature, including the frozen raw material As compared with processed foods manufactured in this way, it was clearly found that vegetables tend to collapse when heated in a microwave oven.

  And in this patent document, the present applicant immerses frozen potatoes and / or frozen beans having a size of 50 mm square or less in an aqueous calcium solution having a calcium concentration of 19 to 162 mM and 80 ° C. or less, and the frozen potatoes and / or There is provided a method for producing a processed food for heating a microwave, characterized by heat-treating frozen beans or a raw material containing frozen potatoes and / or frozen beans at a temperature exceeding 80 ° C. Prior to the production of frozen potatoes and / or frozen beans as raw materials for this method, enzyme deactivation and sterilization treatment called blanching treatment is usually performed. That is, in the method of Patent Document 1, a treatment with an aqueous calcium solution is performed when thawing frozen vegetables that have been subjected to enzyme deactivation treatment.

  However, when a frozen potato or the like is accommodated in a partially shaped container, the collapse preventing effect in the processed food for heating a microwave oven manufactured by the method of Patent Document 1 is not always satisfactory.

  A standing pouch that can stand by itself may be used as a container for storing retort food that is heated in a microwave oven. In the patent document 2, the present applicant discloses an egg-containing food material containing a standing pouch. Patent Document 2 discloses that a standing pouch containing a contained food material is opened, raw eggs are added and mixed, and heated by a microwave oven in a self-supporting state. A standing pouch is, for example, a self-supporting, formed in a bag shape by two opposing side sheets and a bottom sheet arranged so as to be folded upwardly at the lower end side of the two side sheets. It is a possible container. In a state where the standing pouch is self-supporting, a gap is formed between the bottom sheet and a mounting surface such as a table of a microwave oven. In this case, when the processed food containing the standing pouch is heated by a microwave oven, the ingredients such as vegetables located near the bottom of the standing pouch include microwaves reflected from the microwave oven table in multiple directions. It will be irradiated, and it will become easy to disintegrate because ingredients are heated excessively. In particular, frozen potatoes, frozen carrots and the like are extremely easy to collapse, and it has been difficult to heat a processed food containing these ingredients in a microwave oven in a state where they are contained in a standing pouch. A similar problem occurs when using a cup-type container in which a void is formed below the bottom surface.

  On the other hand, various techniques have been developed for preventing the deformation of ingredients such as vegetables when cooking retort foods. Patent Document 3 discloses a frozen potato produced by slicing and branching a potato having a reducing sugar content of about 1% or less and freezing it for about 12 to 48 hours. According to Patent Document 3, this frozen potato has a feature that it does not lose its shape even after thawing and retort sterilization.

  Patent Document 4 also discloses a technique for maintaining a potato texture by slow freezing. Patent Document 5 discloses a method for producing a frozen vegetable that does not soften or boil when thawing and cooking, and maintains the texture.

  In patent document 5, freezing processing is carried out after the fiber reinforcement | strengthening process which requires the 1st process which processes vegetables at the high temperature of 90 degreeC or more, and the 2nd process heat-processed in the aqueous solution containing calcium. To produce frozen vegetables.

  The present inventors investigated the effects of the above-described prior art for the purpose of solving the problem that frozen potatoes and the like collapse during heating with a microwave oven. As a result, by the techniques disclosed in Patent Documents 3 and 4, it was not possible to obtain a sufficient collapse prevention effect by operating the freezing conditions without performing calcium treatment.

  Further, in the technique disclosed in Patent Document 5, in the first step of treatment at high temperature, the enzyme that acts on cell wall reinforcement such as potato is deactivated during the calcium treatment, so that the calcium treatment is performed in the second step. However, a sufficient collapse preventing effect could not be obtained.

JP 2009-33994 A Japanese Patent No. 3729447 JP-A-2-261356 Japanese Patent No. 2657145 Japanese Patent No. 2839455

  An object of this invention is to provide the frozen vegetable which is used for manufacture of processed foods, such as a retort food, and is hard to disintegrate when heated with a microwave oven.

  The inventors have surprisingly found that frozen vegetables obtained by treating raw vegetables that have not been subjected to enzyme deactivation treatment with a calcium ion aqueous solution, blanching treatment, and then slowly freezing them. The present invention has been completed by finding that it has characteristics that do not easily disintegrate even when cooked in the form of processed foods using microwaves and heated in a microwave oven. That is, the present invention includes the following inventions.

(1) a calcium treatment step of treating raw vegetables not subjected to enzyme deactivation treatment with an aqueous solution containing calcium ions;
A blanching step of blanching vegetables after the calcium treatment step;
It is a step of cooling and freezing the vegetables after the blanching step to below -5 ° C, and the time from when the central temperature of the vegetable reaches 0 ° C to -5 ° C is 2 to 72 hours. A method for producing frozen vegetables, comprising a slow freezing step in which cooling is performed.
(2) In the calcium treatment step, further characterized in that the calcium ion concentration of the aqueous solution is 20 to 180 mM, the temperature is 75 ° C. or less, and the treatment time is 5 to 720 minutes. Method.
(3) In the slow freezing process, further cooling is performed so that the time until the core product temperature after the blanching process reaches 10 ° C to 0 ° C is 1 minute to 48 hours. The method of (1) or (2).
(4) The method according to any one of (1) to (3), wherein the vegetable is a potato or a root vegetable.
(5) A frozen vegetable produced by any one of the methods (1) to (4).
(6) Microwave heating, which is obtained by filling a microwave-resistant container with a frozen vegetable or a thawed product produced by any one of the methods (1) to (4) and heat-treating it at a temperature exceeding 80 ° C. Processed food for containers.
(7) The processed food in a container according to (6), wherein the microwave resistant container is a pouch having a sticking part or a folded part of a sheet, or a cup-shaped container having a corner on a side wall or a bottom wall.
(8) The processed food in a container according to (7), wherein the microwave resistant container is a standing pouch.
(9) The method for heating processed food in a container according to (8), wherein the processed food in a container according to (8) is heated by a microwave oven in a state where the upper end side of the standing pouch is opened and left standing.
(11) A processed food for heating in a microwave oven, which is obtained by heat-treating a frozen vegetable produced by the method according to any one of (1) to (4) or a thawed product thereof at a temperature exceeding 80 ° C.

  The frozen vegetable of the present invention has a characteristic that it does not easily collapse even when cooked in the form of processed food and heated in a microwave oven.

FIG. 1A is a plan explanatory view of a standing pouch, and FIG. 1B is a vertical cross-sectional explanatory view taken along line A-A ′ of FIG. Fig.2 (a) shows the cross-sectional schematic diagram in the middle height position (torso part) of the standing pouch 1 filled with the processed food containing frozen vegetable ingredients. FIG. 2B is an enlarged schematic view of the vicinity of the bottom surface 4 of the cross section corresponding to the vertical cross section of FIG. 1B of the standing pouch 1 filled with the processed food. 3A shows a perspective view of a cubic cup-shaped container 30 having a quadrangular cross section, and FIG. 3B shows the middle of the cube cup-shaped container 30 filled with processed food containing frozen vegetable ingredients. The cross-sectional schematic diagram in the height position of is shown. FIG. 4 (a) shows a longitudinal sectional view along the central axis of the cup-shaped container 40 having a circular cross section, and FIG. 4 (b) shows a longitudinal section in a state filled with processed food containing frozen vegetable ingredients. A surface schematic diagram is shown.

1. Ingredients The starting material in the production of the frozen vegetables of the present invention is raw vegetables that have not been subjected to enzyme deactivation treatment. Although the kind of vegetable is not specifically limited, It is preferable to use salmon or root vegetables.

  Potatoes include potatoes and sweet potatoes. As a potato, what kind of potato was frozen as long as it is usually eaten may be used. For example, potato varieties commonly used in processed foods include Hobaku, Sayaka, Baron, Noichi Norin.

  Examples of root vegetables include carrots. As carrots, any kind of carrot may be frozen as long as it is normally eaten.

  Vegetables subjected to the calcium treatment process are raw vegetables that have not been subjected to enzyme deactivation treatment. This is because the cell wall of the vegetable is considered to be strengthened by the calcium treatment, and it is considered that the enzyme (pectin methylesterase) possessed by the vegetable is involved in this cell wall strengthening. The raw vegetables that have not been subjected to enzyme deactivation treatment refer to raw vegetables and those that have not been subjected to treatment to such an extent that pectin methylesterase is deactivated. Typically, it refers to raw vegetables that have not been heat-treated at 80 ° C. or higher, or raw vegetables that have not been subjected to blanching treatment or the like described below.

  Vegetables to be subjected to the calcium treatment step have a size of 50 mm square or less, preferably 9 mm square or more and 50 mm square or less, and a round or cut one can be used. Here, “50 mm square or less” means that one of the ingredients of the vegetable is contained in a virtual cube having a side of 50 mm, and “9 mm square or more” is a virtual cube having a side of 9 mm. It means that one of the ingredients of vegetables is not included in the cube.

2. Method for Producing Frozen Vegetables The frozen vegetables of the present invention are prepared by treating raw vegetables that have not been subjected to enzyme deactivation treatment with an aqueous solution containing calcium ions, and blanching the vegetables after the calcium treatment step. And blanching step and a step of cooling and freezing the vegetable after the blanching step to less than -5 ° C, the time from when the central product temperature of the vegetable reaches 0 ° C to -5 ° C Is produced by a method including a slow freezing step in which the cooling is performed so as to be 2 to 72 hours.

  The mechanism by which the frozen vegetables obtained by this method are resistant to collapse by microwave heating is presumed as follows (however, the scope of the present invention is not limited by this mechanism).

  In the calcium treatment process, pectin methylesterase and the like are involved, and the cell walls of the vegetable cells are strengthened. In the slow freezing process, the internal tissue of the vegetable cells is destroyed by the growth of ice crystals inside the vegetable cells by slow freezing. As a result, a frozen vegetable having a rough internal tissue of the vegetable cell is obtained while maintaining the skeleton of the enhanced cell wall of the vegetable cell.

  In this frozen vegetable, since the cell has a relatively strong cell wall, even when heated at a temperature exceeding 80 ° C., such as retort sterilization, the cell is difficult to contract and the internal tissue of the cell remains rough. Is done. Therefore, when the microwave oven is heated, the internal tissue of the vegetable cell is rough, so that moisture moves within the cell tissue and is easily evaporated through the thin starch film on the cell surface. For this reason, it is considered that the phenomenon that the steam staying in the vegetable cell tissue expands and collapses the cell tissue, that is, the phenomenon that the vegetable collapses due to this phenomenon is unlikely to occur.

  On the other hand, as in Patent Document 1, when calcium treatment is performed on a frozen vegetable after inactivating the enzyme by blanching treatment, pectin methylesterase is deactivated and not involved, so that the cell wall of vegetable cells is enhanced by calcium. Is insufficient. Next, when heating is performed at a temperature exceeding 80 ° C. as in retort sterilization treatment, the vegetable cells shrink during heating, and the inside of the cell tissue is densified. For this reason, at the time of microwave heating, it is estimated that the transpiration of moisture in the cell tissue is hindered, and the steam staying in the cell tissue expands, thereby causing the cell tissue to collapse, thereby causing the vegetables to collapse. .

  Calcium used as an aqueous calcium solution in the present invention can be used regardless of its properties and types as long as it is in the form of a water-soluble salt that can be used in foods. Such water-soluble calcium salts may be used alone or in combination. Examples of water-soluble salts that can be used for commonly distributed foods include calcium lactate and calcium chloride.

  As the calcium aqueous solution, a solution in which a water-soluble calcium salt is dissolved in water so as to have a calcium concentration of 20 to 180 mM can be used, and preferably a calcium concentration of 32 to 97 mM can be used. In addition, a substance other than the water-soluble calcium salt, such as a seasoning such as sodium glutamate, may be present in the calcium aqueous solution as long as it does not inhibit the effect of calcium immersion. The aqueous calcium solution may be in the form of a pretreatment liquid such as a seasoning liquid.

  A method for treating vegetables with an aqueous calcium solution includes immersing the vegetables in an aqueous calcium solution. Vegetables can be immersed in an aqueous calcium solution at a temperature of 75 ° C. or lower, preferably 20 to 70 ° C., more preferably 40 to 65 ° C., for example, for 5 to 720 minutes, preferably 5 to 60 minutes.

  Immersion in an aqueous calcium solution can be performed by a commonly used apparatus or equipment.

  “Branching” in the blanching process refers to heat treatment such as boiled and steamed, which is generally performed when producing frozen vegetables, and stops the action of the enzymes and microorganisms of the vegetables to prevent changes during processing and storage. This process is intended to prevent it.

  Specifically, such blanching is performed under the condition that the core product temperature is maintained at 70 to 95 ° C, preferably 75 to 95 ° C for 1 minute or more, preferably 2 to 30 minutes with hot water or steam. This is done by heating.

  The slow freezing process is a process of cooling and freezing the vegetables after the blanching process (usually the central product temperature of the vegetables immediately after the blanching process is in the range of 70 to 95 ° C) to less than -5 ° C. In addition, cooling is performed so that the time from when the central product temperature of the vegetable reaches 0 ° C. until it reaches −5 ° C. is 2 to 72 hours, preferably 3 to 12 hours.

  By slowly freezing in this manner, ice crystals inside the vegetable cells can be grown, the internal tissue of the vegetable cells can be destroyed, and a coarse tissue having a low density can be formed. When quick freezing is performed outside the slow freezing conditions, the vegetable tissue is likely to collapse during microwave heating. In the present invention, the “center product temperature” refers to the temperature of the portion of the vegetable to be processed that is farthest from the outer surface or the vicinity thereof. It is the temperature of the part, and when it is heated, it is the temperature of the part where the temperature is most difficult to be heated.

  In the slow freezing process, further cooling is performed so that the time until the core product temperature after the blanching process reaches 10 ° C. until it reaches 0 ° C. is 1 minute to 48 hours, preferably 15 minutes to 2 hours. It is more preferable to carry out. Moreover, after the center product temperature of vegetables reaches -5 degreeC, cooling can be continued further, for example, it can be set to -25--80 degreeC.

3. Processed food for microwave oven processing The processed food for microwave oven heating can be prepared by a general means including the frozen vegetable of the present invention or a thawed product thereof. The processed food obtained by heat treatment at a temperature exceeding 80 ° C. containing the frozen vegetable of the present invention or a thawed product thereof is remarkably suppressed even when the food is heated by a microwave oven.

  In the present invention, the “thawed product” refers to a frozen vegetable that has become completely or partially unfrozen. The thawing method and the heating heat source are not particularly limited and can be performed by a commonly used method. For example, it can be performed by thawing frozen vegetables in water at a temperature of 1 to 80 ° C, preferably 20 to 70 ° C. Moreover, it does not specifically limit about the kind of thawing | decompression apparatus, Batch type thawing | decompression using a thawing tank, continuous type thawing | decompression etc. can be utilized.

  The processed food of the present invention is prepared by cooking a raw material containing frozen vegetables or a thawed product thereof alone or together with other raw materials such as sauces, soups, seasonings, spices, and the like (retort) as necessary. Pouch, molding container, etc.), and a temperature exceeding 80 ° C., preferably 90 ° C. to 130 ° C., more preferably 100 ° C. to 130 ° C., for 5 minutes or more, preferably 20 to 100 minutes, It can be manufactured by heat treatment. As such a heat treatment, a retort sterilization treatment can be employed. The processed food can also be prepared as a chilled food or a frozen food. When the intended processing or cooking is substantially performed only by heating by the heat treatment, cooking prior to the heat treatment, etc. to prevent the fire and the texture of ingredients, sauces, etc. from being deteriorated It is not necessary to perform another heat treatment.

  As the manufacturing apparatus used for the above-described heat treatment, any apparatus that is normally used can be used regardless of the type as long as it does not lead to quality deterioration. For example, it can heat-process with the retort sterilizer etc. which are normally used for manufacture of a retort food.

  The processed food for heating a microwave oven of the present invention thus manufactured is in a cooked or semi-cooked state and can be heated using a microwave oven for reheating, finishing cooking, etc. It has the advantage that the vegetables contained in the food are less likely to collapse during microwave heating. The above-described advantages are particularly effectively achieved in a processed food obtained by combining the frozen vegetable of the present invention or a thawed product thereof and a fluid food such as sauce or soup.

  A particularly preferred embodiment of the processed food of the present invention is that the frozen vegetable of the present invention or a thawed product thereof is filled in a microwave-resistant container and heat-treated at a temperature exceeding 80 ° C., and the processed food in a microwave heating container is obtained. (That is, the processed food is hermetically housed in the microwave-resistant container, subjected to heat sterilization, etc., and can be heated in the microwave using the container at the time of eating). The microwave-resistant container can be a microwave-permeable bag-like or molded container that can maintain the physical properties that can hold the contents even when heated with the contents, and can be sealed. That's fine. The size and shape of the container are not particularly limited, but it is generally desirable to have a size corresponding to one meal. The microwave resistant container is preferably a retort container such as a retort pouch when retort sterilization is employed as the heat treatment.

  Examples of the material of the microwave-resistant container include aluminum oxide vapor deposited PET / Nylon / CPP (casting polypropylene), silicon oxide aluminum vapor deposited PET / Nylon / CPP, aluminum oxide vapor deposited PET / CPP, silicon oxide aluminum vapor deposited PET / CPP, and the like. Illustrated. Here, aluminum oxide and silicon oxide are barrier layers. In addition, containers molded from paper laminated with plastic sheets such as polyethylene and polypropylene can also be used, but are not limited to these, and appropriate ones should be used according to the type of target product. Can do.

  As a microwave-resistant container, a pouch formed by one or a plurality of microwave-permeable sheet-like members and having a sticking part or a folding part of the sheet-like member, or having a corner on a side wall or a bottom wall A microwave permeable cup-shaped container can be used. When normal processed food containing vegetables is stored in such a container and heated in a microwave oven, microwaves are applied to the vegetables present at the corners of the cup-shaped container or the pasted or folded portion of the sheet-shaped member in the pouch. There was a problem that vegetables heated from multiple directions and overheated easily collapse. However, the processed food of the present invention is advantageous because the vegetables are not easily collapsed even if the vegetables are stored in such a container and heated in a microwave oven. Therefore, according to the present invention, the processed food is stored in a standing pouch or cup-shaped container, and the upper end side of the pouch is opened and self-supported when eating, or the upper opening of the cup-shaped container is opened. In the state, it becomes possible to realize a form of a processed food in a microwave heating container that can be heated by a microwave oven.

  An example of the microwave resistant container is a standing pouch formed by a plurality of microwave-permeable sheet-like members. The standing pouch is a self-supporting pouch, for example, a bag-like shape formed by two opposing side sheets and a bottom sheet disposed so as to be folded upwardly at the lower end side of the two side sheets. Are formed.

  FIG. 1 shows an example of a standing pouch. FIG. 1A is a plan explanatory view of a standing pouch, and FIG. 1B is a vertical cross-sectional explanatory view taken along line A-A ′ of FIG.

  The standing pouch is a general bottom gusset type standing pouch 1, and the bottom sheet 4, which is folded upward on the lower ends of the two opposing side sheets 2, 3, Attached by the inner lower end and the bottom sticking part 5 of a substantially ship bottom type or a substantially inverted trapezoidal type, and the side sheets 2 and 3 are stuck by the side edge sticking parts 6 and 7 at both side edges. And formed into a bag shape. Both bottom sticking part 5 and side edge sticking parts 6 and 7 can be formed by normal heat sealing. The side sheet and the bottom sheet may be formed by folding one sheet member, or may be formed by two or three sheet members (FIG. 1 is an example of the latter, but this is not limitative). Not)

  FIG. 2 shows a state in which the processed food containing frozen vegetable ingredients 21 to 25 (thawed by processing, hereinafter referred to as vegetable ingredients) obtained by the manufacturing method of the present invention is filled in the standing pouch 1. Show. FIG. 2 (a) shows the middle height of the standing pouch 1 filled with processed food 27 containing vegetable ingredients (the portion excluding vegetable ingredients indicates fluid food such as sauce). The cross-sectional schematic diagram in is shown. FIG. 2B is an enlarged schematic view of the vicinity of the bottom surface 4 of the cross section corresponding to the vertical cross section of FIG. 1B of the standing pouch 1 filled with the processed food 27. The microwaves during microwave heating are schematically shown by arrows. As shown in FIGS. 2 (a) and 2 (b), the vegetable ingredients 21 and 23 located in the vicinity of the side edge sticking part 6 and the bottom sticking part 5 are vegetable ingredients 22 and 24 located in the vicinity of the center of the pouch. In comparison, microwaves are irradiated from multiple directions. Moreover, the vegetable ingredient 25 located near the folding part of the bottom sheet 4 also receives the microwave reflected by the table 26 in the microwave oven in addition to the microwave from the horizontal direction. As described above, in the pouch having the sticking part or the folding part of the sheet, microwaves are applied to the vegetable ingredient located near the sticking part or the folding part from multiple directions. By using this frozen vegetable, even if the ingredients exist in such a position, the ingredients are prevented from collapsing.

  The processed food of the present invention accommodated in the standing pouch is, for example, opened partly or entirely on the upper end side of the standing pouch, heated in a microwave oven in a state of being self-supported on the turntable of the microwave oven, can do. The processed food of the present invention contained in the standing pouch can be distributed in a sealed state, and the consumer opens a part or all of the upper end side of the pouch and heats the pouch together with the microwave to eat. Is possible.

  In FIG. 3, one Embodiment of the cup-shaped container which has a corner | angular part in a side wall and a bottom wall is shown. FIG. 3 (a) shows a perspective view of a cubic cup-shaped container 30 having a square cross section, and FIG. 3 (b) shows frozen vegetable ingredients 32 and 33 (thawed by processing) obtained by the production method of the present invention. Medium height of the cubic cup-shaped container 30 filled with the processed food 34 (the portion excluding the vegetable ingredients indicates a fluid food such as a sauce) including the one in a fresh state, hereinafter referred to as vegetable ingredients. The cross-sectional schematic diagram in a position is shown. Compared with the vegetable ingredient 33 located in the container center part vicinity, the vegetable ingredient 32 located in the corner | angular part of the side wall 31 will receive a microwave from many directions. By using the frozen vegetable of the present invention, even if the ingredients exist at the corners, the ingredients are prevented from collapsing.

  FIG. 4 shows an embodiment of a cup-shaped container having a corner on the bottom wall. FIG. 4 (a) shows a longitudinal sectional view along the central axis of the cup-shaped container 40 having a circular cross section, and FIG. 4 (b) shows a frozen vegetable ingredient (by processing) obtained by the production method of the present invention. The longitudinal cross-sectional schematic diagram in the state filled with the processed food 46 (The part except a vegetable ingredient shows fluid foods, such as a sauce) containing the thing of the thawed | decompressed state and hereafter called a vegetable ingredient is shown. A corner portion is formed by the side wall 41 and the bottom wall 42 at the peripheral edge of the bottom wall 42. The vegetable ingredients 43 located at the corners receive microwaves reflected by the table 45 in the microwave oven as compared with the vegetable ingredients 44 located near the center of the container. Will receive. By using the frozen vegetable of the present invention, even if the ingredients exist at the corners, the ingredients are prevented from collapsing.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, the scope of the present invention is not limited to the form of an Example.

Example 1: Heating in a microwave oven in a standing pouch (1) Preparation of frozen potatoes Raw potatoes (variety: Sayaka, reducing sugar content: about 3%) were cut into 19 mm squares and 1% calcium chloride solution (60 ° C) After being immersed in calcium concentration 90.1 mM for 30 minutes and subjected to calcium treatment, blanching treatment (boiled in water) at 85 ° C. for 5 minutes was performed.

  Thereafter, the potatoes were cooled to a product temperature of 10 ° C. with cooling water, placed in cardboard, and slowly frozen in a freezer at a temperature of −26 ° C. At this time, it takes 1.5 hours for the product temperature in the center of the potato to fall from 10 ° C. to 0 ° C., 7 hours for the temperature to fall from 0 ° C. to −5 ° C., and −5 ° C. to −26 ° C. It took 23 hours to drop to -26 ° C, and reached -26 ° C 31.5 hours after the start of slow freezing.

(2) Preparation of a retort food containing a standing pouch The frozen potato was immersed in warm water at 40 ° C. and thawed, and 30 g of potato with the drained water and 150 g of cream stew sauce were filled into a standing retort pouch, and a retort sterilizer At 122 ° C. for 25 minutes.

(3) Microwave heating The upper part of the standing retort pouch was opened and heated in a microwave oven (RE-SX50 manufactured by Sharp Corporation) for 2 minutes and 30 seconds in a self-standing state. The shape of the potato after heating is "The potato is not cracked and has no cracks.""The potato is not cracked but has cracks.""The potato is cracked by a quarter to a half." Based on the number of retort pouches each shape was confirmed, the scale and frequency of potato decay during heating were confirmed.

  As a result, when the number N of retort pouches was confirmed to be 40, all 40 pieces were found to have no potato cracks or cracks. From this, it was confirmed that the collapse during heating was suppressed.

Comparative Example 1: Calcium treatment after blanching treatment Raw potatoes (variety: Sayaka, reducing sugar content: about 3%) were cut into 19 mm squares, and blanching treatment (boiled) for 5 minutes at 85 ° C. After the treatment, it was immersed in a 1% calcium chloride solution (calcium concentration 90.1 mM) at 60 ° C. for 30 minutes for calcium treatment. After the subsequent slow freezing, a retort food containing a standing pouch was prepared in the same manner as in Example 1 and heated in a microwave oven.

  The magnitude and frequency of potato decay during heating were confirmed in the same manner as in Example 1. Of the number of retort pouches used for confirmation, N = 40, 24 potatoes were not cracked or cracked, potatoes were not cracked, 7 were cracked, 4 were potatoes Nine of them were broken in half to half.

Comparative Example 2: IQF quick freezing, the same as in Example 1 except that the potatoes cooled after the blanching treatment heated in a microwave oven in the standing pouch were snap frozen at -30 ° C with an IQF device instead of slow freezing. A retort food containing a standing pouch was prepared and heated in a microwave oven.

  When the potato is frozen, it takes 6 minutes for the product temperature at the center of the potato to drop from 10 ° C. to 0 ° C., for 8 minutes to drop from 0 ° C. to −5 ° C., and from −5 ° C. to −15 ° C. It took 7 minutes for the temperature to fall to -26 ° C. 1.5 hours after the start of slow freezing.

  The number of retort pouches N = 40 was confirmed for the scale and frequency of potatoes being heated in a microwave oven. As a result, potatoes were not broken and 12 were not cracked, potatoes were not cracked, but 20 were cracked, and potatoes were cracked in a quarter or a half. There were 8 things.

Example 2: Frozen ginseng was prepared in the same manner as in Example 1 using raw ginseng material cut into 7 g of chopped parts instead of frozen ginseng potatoes. (Calcium treatment, blanching treatment and slow freezing were carried out under the same conditions). In this case, the time for the product temperature in the center of the carrot during freezing to pass through each temperature zone was the same as in the case of the potato in Example 1.

  A retort food containing a standing pouch was prepared in the same manner as in Example 1 except that the above frozen carrot was used instead of the frozen potato.

  When the microwave oven was heated in the same manner as in Example 1, the scale and frequency of the carrot during heating was confirmed by the number N of retort pouches = 40. As a result, all 40 pieces were not carrots cracked or cracked. These confirmed that the collapse during heating was suppressed.

1 .. Standing pouch 30 ... Cup-shaped container 40 having corners on side walls ... Cup-shaped containers 21-25, 32, 33, 43, 44 ... having corners on bottom wall

Claims (6)

A calcium treatment step of treating raw vegetables not subjected to enzyme deactivation treatment with an aqueous solution containing 20 to 70 ° C. calcium ions under normal pressure ;
A blanching step of blanching vegetables after the calcium treatment step;
It is a step of cooling and freezing the vegetables after the blanching step to below -5 ° C, and the time from when the central temperature of the vegetable reaches 0 ° C to -5 ° C is 2 to 72 hours. A method for producing frozen vegetables, comprising a slow freezing step in which cooling is performed. In calcium treatment step, the calcium ion concentration of the aqueous solution is 20～180MM, further characterized in that processing time is 5 to 720 minutes, The method of claim 1.   In the slow freezing step, further cooling is performed so that the time from when the central product temperature of the vegetable after the blanching step reaches 10 ° C to 0 ° C is 1 minute to 48 hours, The method of claim 1 or 2.   The method according to claim 1, wherein the vegetable is a potato or a root vegetable.   The frozen vegetables manufactured by the method in any one of Claims 1-4.   Processed food in a microwave heating container obtained by filling a microwave-resistant container filled with the frozen vegetables produced by the method according to any one of claims 1 to 4 and heat-treating it at a temperature exceeding 80 ° C. .

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