JP2008017770A - Method for producing processed root vegetables, and food containing processed root vegetable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing processed root vegetables comprising a method for preventing root vegetables from getting soft: and to provide a product obtained by the method. <P>SOLUTION: The method for producing processed root vegetables comprises the following process: cooking cut vegetables under such a condition that pectin methylesterase falling in the root vegetables is activated; and soaking the cooked root vegetables in calcium salt to strength its tissues followed by storing the vegetables for a prescribed period of time under the condition free from extreme deterioration in quality so as to prevent the vegetables from getting soft. The method enables production of such root vegetables having sufficient hardness to the teeth after cooked (cooked, sterilized) and improved in breakage strength, and cooked food containing such root vegetables through a simple process without requiring any specific processing method and equipment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a processed root vegetable and a food containing the processed root vegetable, and more specifically, for the cut root vegetable, the pectin methylesterase contained in the root vegetable is activated. After heating under conditions, by carrying out a simple treatment of holding for a certain period of time under conditions where the quality does not deteriorate significantly, it is characterized in that it is a root vegetable with improved breaking strength and improved texture and flavor. The present invention relates to a method for producing root vegetables in which softening is prevented and a food using the processed root vegetables.

  It has been conventionally known that vegetables are softened by heat treatment such as cooking or sterilizing vegetables. This is thought to be due to the degradation of pectin, which is ubiquitous in the cell wall and mesenchymal tissue, due to heating. Therefore, conventionally, in order to prevent softening of these vegetables, the vegetables are preliminarily heated at about 55 ° C. to 70 ° C. before the heat treatment such as cooking or sterilization (generally called preheating). A treatment of immersing in a calcium solution is performed.

  The principle of preventing this vegetable softening is that pectin methylesterase in the plant tissue is activated by the dissociation of potassium ions at a temperature of 50 ° C. or higher, and the methyl ester group of pectin is present in the cell tissue and mesophyll tissue. It is considered that the methyl group is liberated and the carboxyl group is increased, and at the same time, calcium and magnesium ions form a bridge with the carboxyl group to harden the tissue. The following examples are given as prior art that is considered to utilize this principle.

  For example, in the prior literature, (1) sterilization heating of carrots heated at 76.7 ° C. and carrots heated at 100 ° C., and comparing the hardness after that, when heated at 76.7 ° C., There is a description that a hardness of about 4 times that obtained when heated at 100 ° C. was obtained. Such reports are also made for fruits such as carrots, onions, radishes, peppers, cauliflowers, potatoes and cherries (Non-patent Document 1).

  For example, as a method for preventing softening of canned carrots, (2) the preheated (pre-heated) carrots are packed in cans and kept firm even after retort sterilization, and the case of heating at 60 ° C. to 65 ° C. is the most It has been reported that the hardness is maintained, and there is no effect at 50 ° C. or lower and 70 ° C. or higher. Moreover, it has been shown that by preheating carrot in a calcium solution, the hardness of the carrot increased in a short time and became hard (Non-Patent Document 2).

  The prior literature proposed (3) “Preventing softening of vegetables and fruits” by preventing the softening by preheating vegetables or fruits in warm water at 45 to 75 ° C. for 10 to 180 minutes. (Patent Document 1). In other documents, (4) “Vegetable softening prevention method”, after immersing vegetables in a calcium solution at a low temperature, the temperature of the aqueous solution is raised to the range of 40 to 70 ° C. in that state. It is described that softening is prevented by holding for a certain time, that the calcium solution immersion performed at a low temperature is 5 hours or more, and that the holding time at 40 to 70 ° C. is 10 to 180 minutes. (Patent Document 2).

  Other references include (5) “softening prevention vegetable and vegetable softening prevention method” and (6) “vegetable softening prevention method” as a high-concentration sugar solution (60% by weight sugar solution in the examples). ) For a long time (16 hours in the examples), it is described that softening can be prevented (Patent Documents 3 and 4).

  In addition, other documents include (7) “Vegetables heat treatment method”, in order to heat cook and / or heat sterilize vegetables, steam at 60 to 90 ° C. for 5 to 100 minutes in advance. It is described that the taste and texture of vegetables after heating (cooking and sterilization) can be maintained well by direct contact (Patent Document 5).

  When the methods (3) to (7) are used, softening after heating (cooking and sterilization) can be prevented to some extent. However, this type of method requires a long treatment time or a high-concentration solution when a vegetable that is sufficiently hard after heating and has a firm texture is required. There was a problem that it became inefficient in industrial production. In addition, the vegetables treated with such a high concentration calcium solution for a long time are hardened, but unlike the original vegetable flavor and texture, for example, in carrots, after being heated (cooked and sterilized), There was a problem of having a muscular texture like that left behind.

  In addition to the technique for improving the hardness after heating (cooking and sterilization) by preheating as described above, calcium solution immersion, or a combination thereof, the following known techniques can be cited. For example, in the prior literature, as a “method for preventing cooking of vegetables”, prior to heating (cooking and sterilization) of vegetables, the vegetables are put into a calcium salt aqueous solution and subjected to reduced pressure treatment, thereby reducing the cooking errors. It is described to prevent (Patent Document 6).

  In another document, as a “food material reforming method”, the food material is immersed in a solution containing the enzyme and pressurized at 1.04 to 50 atm or less to penetrate the enzyme into the food material. And improving the hardness by causing an enzyme reaction inside the food material (Patent Document 7). In addition, in other documents, the hardness after cooking of vegetables subjected to high pressure treatment (400 MPa) is improved from that of untreated, by using calcium soaking and high pressure treatment (400 MPa) in combination, Further, it is described that the hardness after heating is improved (Non-patent Document 3).

  However, when the above method is used, pressure operation such as reduced pressure or high pressure is required, so there is a disadvantage that an expensive processing device is required, and since it is a complicated processing step, an inexpensive vegetable raw material is used. There is also a drawback that it is not cost effective when is required. Therefore, in this technical field, special processing methods and equipment such as high-concentration solution soaking, long-time soaking treatment, pressure operation and the like are not required for treating vegetables, and it is simpler and easier. New processing technology that can produce vegetables that have a natural crunchy texture and flavor that does not feel stiff, with sufficient crunchiness after heating (cooking and sterilization) The development of was strongly sought.

JP 54-107542 A JP 60-237957 A Japanese Patent Laid-Open No. 9-327276 Japanese Patent Laid-Open No. 10-327794 JP-A-11-155513 JP-A-3-285651 JP 2004-89181 A Pectin Its Science and Food Texture, Takaaki Manabe, Kobo Shobo, p. 76-79 (2001) Prevention of softening of canned carrots, Toyo Shokuhin Junior College Research Report, No. 23, p. 47-56 (2000) Non-Enzymatic Depolymerization of Carrot Pectin: Toward a Better Understanding of Carrot Texture During Thermal Processing, Journal of Food Science, Vol. 71, No. 1, E1-E9, 2006

  In such a situation, in view of the prior art, the present inventors aim to develop a method for preventing softening of vegetables by a simple method without requiring a special treatment method and equipment. As a result of intensive research, the cut root vegetables were treated so that the pectin methylesterase contained in the root vegetables was activated, and then immersed in calcium salt in the same or another process for tissue strengthening treatment. After implementing, it discovered that the breaking strength of root vegetables could be improved by implementing a simple process of holding for a certain period of time, and completed the present invention.

  The present invention does not require a special treatment method and equipment, is simpler, has a sufficient crunchiness after heating (cooking and sterilization), has improved breaking strength, and does not feel streak. An object of the present invention is to provide a method for producing a root vegetable that prevents softening and enables the production of a root vegetable having a natural texture and flavor, and a food using the processed root vegetable.

The present invention for solving the above-described problems comprises the following technical means.
(1) After treating the cut root vegetables under conditions such that the pectin methylesterase contained in the root vegetables is activated, and performing a tissue strengthening treatment by immersing in calcium salt in the same or another step, A method for producing a processed root vegetable that prevents softening, characterized in that the root vegetable is improved in breaking strength after heat treatment by being held for a certain period of time under conditions in which the quality is not significantly deteriorated.
(2) The method for producing processed root vegetables that prevents softening according to (1) above, wherein the root vegetables are maintained for a certain period of time at 0 ° C. to 10 ° C., which is a condition in which the quality is not significantly deteriorated.
(3) Production of processed root vegetables in which root vegetables are heat-treated at 60 ° C. to 85 ° C. for 10 minutes to 10 seconds as an activation treatment of the pectin methyl esterase, wherein softening of the root vegetables according to (1) is prevented. Method.
(4) The method for producing processed root vegetables that prevents softening according to (1) above, wherein the acid solution is immersed before, during, or during the pectin methylesterase activation treatment.
(5) The method for producing processed root vegetables that prevents softening according to (4), wherein the acid solution is a citric acid solution.
(6) A cut root vegetable characterized in that the breaking strength after cooking and / or sterilization is improved using the processed root vegetable produced by the method according to any one of (1) to (5) above Or food containing cut root vegetables.
(7) After treating the cut root vegetables under conditions that activate the pectin methylesterase contained in the root vegetables, and after performing tissue strengthening treatment by immersing in calcium salt in the same or another step Heat-treated food containing root vegetables characterized in that processed root vegetables are prepared by holding for a certain period of time under conditions that do not significantly degrade the quality, and then the food containing the obtained processed root vegetables is heat-treated Manufacturing method.

Next, the present invention will be described in more detail.
The present invention is a method for producing a processed root vegetable in which softening is prevented, wherein the cut root vegetable is treated under conditions such that pectin methylesterase contained in the root vegetable is activated, and is the same or different process After being subjected to tissue strengthening treatment by immersing in calcium salt at, the root vegetables with improved breaking strength after heat treatment are maintained by maintaining for a certain period of time under conditions where the quality is not significantly deteriorated. is there. In addition, the present invention is a cut root vegetable or a food containing cut root vegetable, and the breaking strength after cooking and / or sterilization is improved using the processed root vegetable produced by the above-described method. It is characterized by this. Furthermore, the present invention is a method for producing a cooked food, wherein the cut root vegetables are treated under conditions such that the pectin methylesterase contained in the root vegetables is activated, and the same or different steps. After processing the tissue strengthening treatment by immersing in calcium salt, prepare processed root vegetables by holding for a certain period of time under the condition that the quality does not deteriorate significantly, and then heat-treat the food containing the obtained processed root vegetables It is characterized by doing.

  The present invention relates to a method for producing root vegetables in which softening is prevented. The cut root vegetables are subjected to pectin methylesterase activation treatment contained in the root vegetables, and further subjected to tissue strengthening treatment such as immersion in calcium salt. After being carried out, it is a simple process of maintaining for a certain period of time under conditions where the quality does not deteriorate significantly, for example, freezing and drying do not occur, or under the condition of no decay, and there is sufficient texture after heating (cooking, sterilization). The root vegetables are characterized in that the breaking strength is improved and a natural crunchy and flavor-free flavor is obtained.

  As a method of holding for a certain period of time under the condition that the quality is not significantly deteriorated, a method of holding the root vegetables for a certain period of time under a condition in which freezing or drying does not occur and decay does not proceed is exemplified. If the temperature is too low, there is a possibility of freezing, and if it is too high, there is a concern that drying and decay will proceed. Therefore, a method of holding at 0 ° C. to 10 ° C. for a certain period is preferable. Examples of the holding means include a refrigerator, a constant temperature storage, a low temperature storage, a constant temperature storage, and an incubator. In the present invention, performing the process of holding for a certain period under the condition that the quality is not significantly deteriorated means that the above-described process is performed.

  Examples of the activation treatment of pectin methyl esterase include a method of heating root vegetables under heating conditions such that the pectin methyl esterase enzyme is not active. For example, in the case of 15 mm dice carrots, For example, heating conditions of 10 to 10 minutes, 65 ° C. for 30 seconds to 3 minutes, 70 ° C. for 15 seconds to 2 minutes, and 85 ° C. for about 10 seconds to 1 minute can be exemplified.

  As the heating condition, it is necessary to select a suitable condition as appropriate depending on the type of the root vegetable, the cut size, the processing scale, and the performance of the processing equipment. Further, the heating medium may be any of steam, hot water immersion, far infrared, microwave, hot air, etc., preferably steam and hot water immersion are exemplified.

  The acid solution immersion can be performed either before or after the treatment for activating pectin methylesterase or during the treatment. In this case, any acid can be used as long as it can be used for preventing browning, such as citric acid, acetic acid, gluconic acid, ascorbic acid, strongly acidic water, and electrolytic hyposulfite. For example, when the citric acid solution is immersed in a 15 mm die of carrot, the concentration of the citric acid solution is 0.03 to 1.0% by weight (pH 4 to 2.2), preferably 0.05 to 0.2% by weight. % (PH 3.4 to 2.7).

  It is possible to carry out immersion with various solutions (for example, vitamin E) for preventing deterioration of quality such as oxidation, before, during or after the activation of pectin methylesterase. It is also possible to activate the pectin methylesterase enzyme by freezing and thawing as appropriate.

  Examples of the tissue strengthening treatment include a method of accelerating the binding between a carboxyl group in pectin and calcium by immersing root vegetables in a calcium salt solution. The tissue strengthening treatment can be performed either before or after the treatment for activating pectin methylesterase or during the treatment. Any calcium salt can be used as long as it can be used as food, such as calcium chloride, calcium lactate, calcium carbonate, and calcium acetate.

  For example, when the calcium chloride solution is immersed in a carrot with a 15 mm die, the concentration is suitably 0.1 to 4.0% by weight, 5 to 75 ° C. for 5 to 120 minutes, preferably 0.25 to 1.0% by weight and 55 to 65 ° C. for 10 to 30 minutes. As for the processing conditions, it is necessary to select optimal conditions appropriately depending on the type of root vegetables to be processed, the cut size, the processing scale, the performance of the processing equipment, and the like.

  As heat treatment conditions to be carried out after the above treatment, in the case of pressure heat treatment, 101 ° C. to 140 ° C., 90 minutes to 3 minutes, preferably 115 ° C. to 130 ° C., 30 minutes to 10 minutes, high temperature short time treatment 100 ° C. to 140 ° C., 5 minutes to 2 seconds, preferably 110 ° C. to 135 ° C., 3 minutes to 2 seconds, in the case of low temperature treatment, 55 ° C. to 100 ° C., 90 minutes to 5 minutes, preferably 70 ° C. to 100 ° C. C., 60 minutes to 10 minutes are exemplified.

  The present invention is used as a half-processed ingredient or ingredient for preservative foods as a kind of root vegetables, and can be applied to all root vegetables that tend to soften after heating (after cooking and sterilization). More effective effects can be obtained by applying to root vegetables such as burdock.

The present invention has the following effects.
(1) Softening of root vegetables can be prevented by carrying out a simple treatment in which tissue strengthening treatment is used in combination with pectin methyl esterase enzyme remaining in root vegetables and then held under a certain condition. .
(2) According to the present invention, even after heating (cooking and sterilization), the crunch remains sufficiently, that is, the breaking strength is improved and the natural crunch that does not feel mushy, and the root vegetable becomes flavored. Can be obtained.
(3) Processed root vegetables that have been subjected to the above treatment to prevent softening and cooked foods using the root vegetables can be manufactured and provided.

  EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.

  After peeling off commercially available carrots (variety: Koyo No.2), cut the meat part into 15 mm dice and immerse it in hot water set at 85 ° C. for 1 minute to activate pectin methylesterase And cooled with cooling water (20 ° C.) for 3 minutes. Thereafter, this was dipped in a 0.5 wt% calcium chloride solution (20 ° C.) for 60 minutes to perform tissue strengthening treatment, and then a carrot that was kept in a refrigerator at 4 ° C. for 48 hours was produced.

  The carrot after being held in the refrigerator was filled and sealed in a retort pouch together with a curry sauce, and then sterilized by heating under pressure at 122 ° C. for 23 minutes. After sterilization under pressure and heat, the pouch was immersed in cooling water at 20 ° C. and cooled for 12 hours. Then, carrots were taken out from the curry sauce, pierced strength was measured with a rheometer (YAMADEN RE-3305), and breaking strength and breaking strain rate were calculated. The measurement conditions were a load cell load amount of 2 kgf, a 3 mm diameter circular plunger, and a penetration speed of 1 mm / s.

Comparative Example 1-A
After peeling off commercially available carrot (variety: Koyo No.2), the meat part was cut into a 15 mm die, immersed in hot water set at 85 ° C. for 1 minute, and then cooled with cooling water (20 ° C.) for 3 minutes. . Then, after immersing this in a 0.5 wt% calcium chloride solution (20 ° C.) for 60 minutes, ginseng (which was sterilized under pressure and heat immediately after immersion in the calcium chloride solution) was prepared. . Thereafter, the breaking strength / breaking strain rate was calculated in the same manner as in Example 1 to obtain Comparative Example 1-A.

Comparative Example 1-B
After peeling off commercially available carrot (variety: Koyo No.2), the meat part was cut into a 15 mm die and then immersed in a 0.5 wt% calcium chloride solution (20 ° C.) for 60 minutes without heat treatment. In addition, carrots kept in a refrigerator at 4 ° C. for 48 hours were prepared. Thereafter, the breaking strength / breaking strain rate was calculated in the same manner as in Example 1 to obtain Comparative Example 1-B.

Comparative Example 1-C
After peeling off commercially available carrot (variety: Koyo No.2), the meat part was cut into a 15 mm die and then immersed in a 0.5 wt% calcium chloride solution (20 ° C.) for 60 minutes without heat treatment. After that, ginseng (which was sterilized by heating under pressure immediately after immersion in calcium chloride) was prepared. Thereafter, the breaking strength / breaking strain rate was calculated in the same manner as in Example 1 to obtain Comparative Example 1-C.

Comparative Example 1-D
After peeling off commercially available carrot (variety: Koyo No.2), the meat part was cut into a 15 mm die, then immersed in hot water set at 85 ° C for 1 minute, and then cooled with cooling water (20 ° C) for 3 minutes did. Furthermore, the carrot kept for 48 hours in the 4 degreeC refrigerator was produced. Thereafter, the breaking strength / breaking strain rate was calculated in the same manner as in Example 1 to obtain Comparative Example 1-D.

Comparative Example 1-E
After peeling off commercially available carrot (variety: Koyo No.2), the meat part was cut into a 15 mm die, then immersed in hot water set at 85 ° C. for 1 minute, and cooled with cooling water (20 ° C.) for 3 minutes. Thereafter, carrots (no pressure heat sterilization was performed immediately after heating at 85 ° C. for 1 minute) without any holding period were prepared. Thereafter, the breaking strength / breaking strain rate was calculated in the same manner as in Example 1 to obtain Comparative Example 1-E.

The results are shown below.
Breaking strength (× 10 ⁴ Pa) Breaking strain rate (%)
Example 1 16 10
Comparative Example 1-A 13 9
Comparative Example 1-B 8 12
Comparative Example 1-C 7 12
Comparative Example 1-D 8 10
Comparative Example 1-E 8 10

  In the case of carrots using both weak heating (85 ° C.-1 min) and calcium solution immersion (tissue strengthening), the crunch (breaking strength) after pressurizing and heating sterilization is further maintained by holding it in a refrigerator at 4 ° C. for 48 hours. It turns out that it can improve. Moreover, the carrot after pressurizing and heat-sterilizing did not feel a muscular flavor, and it was natural. In addition, in only calcium solution immersion at 20 ° C. (Comparative Examples 1-B and C) and only weak heating (Comparative Examples 1-D and E), even after holding at 4 ° C., after the heat treatment It was found that no hardness improvement effect was observed.

  After peeling off commercially available carrots (variety: Koyo No.2), the meat part was cut into 15 mm dice and immersed in a 0.5 wt% calcium chloride solution set at 60 ° C. for 10 minutes. After performing the activation treatment and the tissue strengthening treatment, it was cooled with cooling water (20 ° C.) for 3 minutes. Furthermore, the carrot kept for 48 hours in the 4 degreeC refrigerator was produced. The carrot after being held in the refrigerator was filled and sealed in a retort pouch together with a curry sauce, and then sterilized by heating under pressure at 122 ° C. for 23 minutes. After sterilization under pressure and heat, the pouch was immersed in cooling water at 20 ° C. and cooled for 12 hours. Then, carrots were taken out from the curry sauce, pierced strength was measured with a rheometer (YAMADEN RE-3305), and breaking strength and breaking strain rate were calculated. The measurement conditions were a load cell load amount of 2 kgf, a 3 mm diameter circular plunger, and a penetration speed of 1 mm / s.

Comparative Example 2
After peeling off commercially available carrot (variety: Koyo No.2), the meat part was cut into a 15 mm die and immersed in a 0.5 wt% calcium chloride solution set at 60 ° C. for 10 minutes, followed by cooling water (20 ) For 3 minutes. Thereafter, the carrots of this treatment were taken as carrots without any holding period (calcium chloride soaked and subjected to pressure heat sterilization immediately after cooling) in the same manner as in Example 2 above, and the breaking strength and breaking strain ratio were determined. The result was calculated as Comparative Example 2.

The results are shown below.
Breaking strength (× 10 ⁴ Pa) Breaking strain rate (%)
Example 2 26 10
Comparative Example 2 15 9

  In the case of carrots subjected to a heat treatment in a calcium solution for a short time, it was found that the texture (breaking strength) after pressurization and heat sterilization can be further improved by holding in a refrigerator at 4 ° C. for 48 hours. Moreover, the carrot after pressurizing and heat-sterilizing did not feel a muscular flavor, and it was natural.

  After peeling off commercially available radish, cut into 15 mm dice, soaked in 0.5 wt% calcium chloride solution (60 ° C.) for 10 minutes, and after pectin methylesterase activation treatment and tissue strengthening treatment, Cooled with cooling water (20 ° C.) for 3 minutes. Thereafter, the radish was prepared by holding it in a refrigerator at 4 ° C. for 48 hours.

  The radish stored in the refrigerator was filled and sealed in a retort pouch together with curry sauce, and then sterilized by heating under pressure at 122 ° C. for 23 minutes. After sterilization under pressure and heat, the pouch was immersed in cooling water at 20 ° C. and cooled for 12 hours. Then, the radish was taken out from the curry sauce, pierced strength was measured with a rheometer (YAMADEN RE-3305), and the breaking strength and breaking strain rate were calculated. The measurement conditions were as follows: the load cell load was 2 kgf, a circular plunger with a diameter of 3 mm, and a penetration speed of 1 mm / s.

Comparative Example 3-A
After peeling a commercially available radish, it was cut into a 15 mm die, immersed in a 0.5 wt% calcium chloride solution (60 ° C.) for 10 minutes, and then cooled with cooling water (20 ° C.) for 3 minutes. Thereafter, a holding period was not set at all (pressure sterilization was performed immediately after cooling) to prepare radishes. Thereafter, the breaking strength / breaking strain rate was calculated in the same manner as in Example 3 to obtain Comparative Example 3-A.

Comparative Example 3-B
After peeling a commercially available radish, it was cut into a 15 mm die and immersed in hot water set at 90 ° C. for 5 minutes (branching treatment). Then, the radish kept for 48 hours in the 4 degreeC refrigerator was produced. After storage, the breaking strength / breaking strain rate was calculated in the same manner as in Example 3 to obtain Comparative Example 3-B.

Comparative Example 3-C
After peeling a commercially available radish, it was cut into a 15 mm die and immersed in hot water set at 90 ° C. for 5 minutes (branching treatment). Thereafter, a holding period was not set at all (pressure sterilization was performed immediately after immersion) to produce radishes. Thereafter, the breaking strength and breaking strain rate were calculated in the same manner as in Example 3 to obtain Comparative Example 3-C.

The results are shown below.
Breaking strength (× 10 ⁴ Pa) Breaking strain rate (%)
Example 3 64 19
Comparative Example 3-A 37 16
Comparative Example 3-B 13 15
Comparative Example 3-C 12 14

  The cut radish can be heat-treated in a calcium solution for a short time and then kept in a refrigerator at 4 ° C. for 48 hours to further improve the breaking strength after sterilization under pressure, that is, the texture of the teeth. It was also found that the radish obtained in this way does not feel unnatural texture such as streak. On the other hand, in the radish that had been subjected to the blanching treatment, no improvement in tooth response was observed even when kept at 4 ° C.

  After peeling commercially available burdock, cut to 15 mm thickness, soak for 10 minutes in 0.5 wt% calcium chloride solution (60 ° C.), perform pectin methylesterase activation treatment and tissue strengthening treatment, then cool water Cooled at (20 ° C.) for 3 minutes. Thereafter, the processed burdock was produced by holding it in a refrigerator at 4 ° C. for 48 hours.

  After the burdock stored in the refrigerator was filled and sealed in a retort pouch together with a curry sauce, it was sterilized by heating under pressure at 122 ° C. for 23 minutes. After sterilization under pressure and heat, the pouch was immersed in cooling water at 20 ° C. and cooled for 12 hours. Thereafter, the burdock was taken out from the curry sauce, pierced strength was measured with a rheometer (YAMADEN RE-3305), and the breaking strength and breaking strain rate were calculated. The measurement conditions were as follows: the load cell load was 2 kgf, a circular plunger with a diameter of 3 mm, and a penetration speed of 1 mm / s.

Comparative Example 4
After peeling off a commercially available burdock, it was cut to a thickness of 15 mm, immersed in a 0.5 wt% calcium chloride solution (60 ° C.) for 10 minutes, and then cooled with cooling water (20 ° C.) for 3 minutes. Thereafter, a burdock was produced without any holding period (pressure sterilization was performed immediately after cooling). Thereafter, the breaking strength and breaking strain rate were calculated in the same manner as in Example 4 to obtain Comparative Example 4.

The results are shown below.
Breaking strength (× 10 ⁴ Pa) Breaking strain rate (%)
Example 6 53 14
Comparative Example 6 33 12

  The cut burdock is heat-treated in a calcium solution for a short time, and then kept in a refrigerator at 4 ° C. for 48 hours, so that the breaking strength after pressure sterilization can be greatly improved. It was found that the burdock thus obtained felt a very firm texture even after sterilization under pressure.

  As described above in detail, the present invention relates to a method for preventing softening of root vegetables and its product, and according to the present invention, in a state in which the pectin methylesterase enzyme of the root vegetables remains, a tissue strengthening treatment is used in combination. By the simple treatment of holding under a certain condition, softening of root vegetables can be prevented. According to the present invention, even after heating (cooking and sterilization), the crunch remains sufficiently, that is, the breaking strength is improved and the natural crunch that does not feel streaky, the root vegetables that are flavored, and the root vegetables A cooked food product containing the same can be produced and provided.

Claims (7)

  After processing the cut root vegetables under conditions that activate the pectin methylesterase contained in the root vegetables, and after performing tissue strengthening treatment by immersing in calcium salt in the same or another step, the quality is remarkably high. A method for producing processed root vegetables that prevents softening, characterized in that the root vegetables are improved in breaking strength after heat treatment by holding them for a certain period of time under conditions that do not deteriorate.   The method for producing processed root vegetables with softening prevented according to claim 1, wherein the root vegetables are held for a certain period of time at 0 ° C to 10 ° C, which is a condition in which the quality is not significantly deteriorated.   The method for producing processed root vegetables according to claim 1, wherein the root vegetables are heat-treated at 60 ° C to 85 ° C for 10 minutes to 10 seconds as the activation treatment of the pectin methylesterase.   The method for producing a processed root vegetable that prevents softening according to claim 1, wherein the acid solution is immersed before, during or after the pectin methylesterase activation treatment.   The method for producing a processed root vegetable that prevents softening according to claim 4, wherein the acid solution is a citric acid solution.   Cut root vegetables or cut root vegetables characterized in that the breaking strength after cooking and / or sterilization is improved using the processed root vegetables produced by the method according to any one of claims 1 to 5. Containing food.   The cut root vegetables are treated under conditions that activate the pectin methylesterase contained in the root vegetables, and after the tissue strengthening treatment is performed by immersing in calcium salt in the same or different process, the quality is significantly improved. A method for producing a heat-treated food containing root vegetables characterized in that processed root vegetables are prepared by holding for a certain period of time under conditions that do not deteriorate, and then the food containing the obtained processed root vegetables is heat-treated .