JP2007129995A - Method for producing food product by joule heating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating method for a solid-liquid mixed food product of solid food and liquid food, which is capable of evenly Joule-heating the food, to provide a method for producing the solid-liquid mixed food product using the treating method and Joule heating, and to provide the solid-liquid mixed food product obtained by the method. <P>SOLUTION: This method for producing the solid-liquid mixed food product comprises (a1) a process of freezing solid food, thawing or unthawing the solid food to be mixed with liquid food to obtain a solid-liquid mixed food product, or (a2) a process of mixing and freezing solid food and the liquid food to obtain a solid-liquid mixed food product, and (b) a process of Joule heating the solid-liquid mixed food product. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a solid-liquid mixed food comprising a solid food and a liquid food using Joule heating, and more particularly to a method for treating a solid-liquid mixed food for Joule heating.

  Joule heating of food is a heating technique for cooking and / or sterilizing or sterilizing food using heat generated by electric resistance (joule heat) generated when a direct current is applied to solid and / or liquid food. .

  Conventional external heating methods based on heat conduction (for example, retort heating methods) often perform excessive heating in comparison with general cooking heating in order to obtain a sufficient sterilizing effect. There was a tendency for the color tone to be lost and the taste of the product to be uniform. On the other hand, the Joule heating method is known as an excellent heating method in which the food is heated from the inside by Joule heat, so that the heating time is relatively short, and the heat deterioration such as flavor and color tone of the food hardly occurs.

  However, in solid-liquid mixed foods consisting of solid foods and liquid foods, the electrical resistivity differs for each type of solid food, and even in the same solid food, the electrical resistivity differs for each part due to structural anisotropy, Furthermore, since the electrical resistivity also changes due to changes in the structure of the structure due to cooking, a uniform electrical resistivity cannot be obtained in the solid-liquid mixed food, which causes uneven heating. This has been one of the major reasons why the Joule heating method has not yet been implemented industrially in solid-liquid mixed food materials (Non-Patent Documents 1 to 4).

In order to solve the above problems, several patent applications have been filed (Patent Documents 1 to 8). Many of them are intended to homogenize the electrical resistivity of the food by pre-processing (heating or dipping) the solid food with the electrolyte solution, or by adjusting the electrical resistivity of the solid food and the liquid food. This is intended for uniform heating in Joule heating. However, in a method of heating in an electrolyte solution, for example, a method of heating a raw vegetable solid food of Patent Document 6 to 40 ° C. or higher to damage the cell wall and increase the conductivity, The rate is not uniform enough, the soaking method takes a long time for the salting process, and the method for adjusting the electrical resistivity of the solid food and the liquid food needs to be processed for each ingredient. Restrictions remained, and it could not be said that the problem was solved sufficiently in practice.
Miki Akiyama: Joule heating technology-its features and applications-, Japan Food Science, 41 (6), 47-53 (2002) Kunihiko Uemura: Basic theory of Joule heating, Japan Food Science, 41 (6), 55-60 (2002) Norihiko Sugie: Joule heating device and its application, Japan Food Science, 41 (7), 83-89 (2002) Ryohei Matsuyama: Sterilization of solid-liquid mixed food by Joule heat treatment system, Japan Food Science, 41 (7), 95-99 (2002) JP-A-60-27349 JP 60-251851 Special table flat 8-504322 JP-A-11-276097 JP 2003-299446 A JP 6-45 JP 7-34720 Japanese Patent No. 3564642

  The present invention provides uniform electrical resistivity variation due to the inherent electrical conductivity of solid foods, due to individual differences in solid foods, due to structural non-uniformity at each part of the solid foods, or due to changes in tissue structure due to heating, etc. Is obtained by a method for treating a solid-liquid mixed food comprising a solid food and a liquid food that enables uniform joule heating of the food, a method for producing the solid-liquid mixed food using the treatment method and Joule heating, and a method for producing the same A solid-liquid mixed food is provided.

(1) The present invention
(A1) After freezing the solid food, the solid food is mixed with liquid food without thawing or thawing to obtain a solid-liquid mixed food, or (a2) After mixing the solid food and liquid food, this is frozen To obtain a solid-liquid mixed food,
And (b) a method for producing a solid-liquid mixed food, comprising a step of joule heating the solid-liquid mixed food.
(2) This invention relates to the manufacturing method of the solid-liquid mixed food of Claim 1 which sterilizes or sterilizes a solid-liquid mixed food by the (b) process of (1).
(3) This invention relates to the solid-liquid mixed food obtained by the manufacturing method of the solid-liquid mixed food as described in (1) or (2).

  According to the method of the present invention, variation in the electrical resistance value of the solid food due to the electrical conductivity inherent to the solid food, due to individual differences in the solid food, due to structural heterogeneity for each part of the solid food, or due to changes in the tissue structure due to heating, etc. Is eliminated, and the electric resistance value of the solid food can be made uniform, so that the food can be uniformly heated. Therefore, according to the method of the present invention, it is possible to manufacture, cook, sterilize or sterilize a solid-liquid mixed food consisting of solid food and liquid food by Joule heating.

  Furthermore, the method of the present invention does not require sufficient cooking or excessive heating to obtain a sterilizing or sterilizing effect unlike an external heating method (for example, a retort heating method) by heat conduction, and the solid food is heated by Joule heat. Since the entire interior can be directly heated, the heating time can be shortened. For this reason, the quality of food ingredients such as flavor and color tone is impaired by excessive heating, resulting in a uniform taste and replacing the prevalent external heating methods (for example, retort heating methods). Production of high-quality foods (heat-sterilized or heat-sterilized foods) having a variety of flavors and maintaining quality such as flavor and color tone becomes possible.

  The food used in the present invention means food, and the food used in the present invention includes not only food after cooking but also food material before cooking, food during cooking, or food material. The food used in the present invention includes not only foods for humans but also foods for animals such as livestock animal feed or pet food.

The solid food used in the present invention refers to a food having a certain shape and volume, for example, vegetables such as carrots, daikon, potatoes, onions, celery, cabbage, fruits such as strawberries, apples, soybeans, green peas, Beans such as beans, cereals such as corn, wheat, rice, or fungi such as mushrooms, shiitake, etc., raw vegetable foods including seaweed such as seaweed, kelp, mekabu, etc. or heating, drying, shredding, Plant foods that have been processed such as molding; live animal foods including beef, pork, chicken and other livestock meat such as salmon, salmon, salmon, salmon, salmon, clams, salmon, salmon Animal food that has been processed by heating, drying, shredding, molding, or the like; or a mixture of these raw and / or processed vegetable foods and animal foods, or a combination thereof. It is. Here, the vegetable food means the plant itself or a food obtained from the plant, and the animal food means the animal itself or a food obtained from the animal body.
The solid food used in the present invention is preferably a vegetable food that is generally susceptible to non-uniform heating in Joule heating. In addition, since the non-uniform heating in Joule heating is generally less likely to occur as the size of the solid food is smaller, the size of the solid food used in the present invention is 3 mm or more, more preferably 5 mm, in order to obtain the advantageous effects of the present invention. As described above, those having a diameter or thickness of 10 mm or more are more preferable. Therefore, in general, uneven heating in Joule heating is unlikely to occur, and raw seafood made into minced raw livestock meat or those processed by molding or the like are not included in the solid food of the present invention.

  The liquid food used in the present invention refers to food that contains water and has fluidity, for example, water such as tap water, pure water, ion-exchanged water, mineral water, and electrolytes, seasonings, and thickeners as appropriate. Water comprising, for example, saline, tidal juice, stock, or a mixture of water and fat or an emulsion of water and fat, such as curry sauce, white sauce, Dumigrassauce, tomato sauce, grilled meat sauce Or soups such as consomme soup, potage soup, miso soup and pork soup. Although pure water itself does not have electrical conductivity, most of the solid food originally contains an electrolyte necessary for energization, so that pure water also has electrical conductivity when mixed with solid food. Become. Therefore, pure water is also included in the liquid food.

  Here, electrolytes include sodium chloride, magnesium chloride, calcium chloride, potassium chloride, sodium phosphate, potassium phosphate, potassium carbonate, iron sulfate, etc. It is not limited to these as long as it can be used, and may be used alone or in combination. As mentioned above, most solid foods originally contain the electrolyte necessary to energize, so it may or may not be added to the liquid food, but the concentration of the electrolyte in the case of addition was applied. There is no particular limitation as long as it is a concentration at which electricity can sometimes flow.

  The solid-liquid mixed food used in the present invention is a food containing the above-described solid food and liquid food, and examples of the form include the following. That is, liquid foods such as sauces or soups as a main component, solid-liquid mixed foods in a form containing solid foods therein, or solid foods as main components, and liquids such as water, sauces or soups It is a solid-liquid mixed food in the form of adding food. Specific examples of the former include curry, stew, beef stroganoff, borsch, minestrone, miso soup, Chinese rice sauce, and clam chowder. Specific examples of the latter include various food ingredients for use in other foods, beef bowl ingredients, hamburger, Chikuzenni, meat potato, spaghetti, and the like. In addition, the food of the form which contains approximately equal amounts of solid food and liquid food, such as miscellaneous cooking or rice cake, is also included in the solid-liquid mixed food in the present invention. Therefore, in the solid-liquid mixed food of the present invention, the ratio of the solid food and the liquid food in the solid-liquid mixed food need not be particularly limited, but the amount of the liquid food is the minimum amount necessary for energization. including. In addition, the solid-liquid mixed food of the present invention includes not only food as a finished product but also food ingredients for use in other foods.

  Freezing used in the present invention means, for example, freezing moisture in food by placing the food at a temperature below the freezing point. The freezing of the water may be a part of the food, but in order to obtain a sufficient effect of the present invention, it is preferable to freeze most of the water in the food, particularly the solid food. It is well known to those skilled in the art that the time for freezing a solid food can be arbitrarily changed depending on the freezing temperature, the type, size or amount of the food. The freezing method is not limited to freezing methods such as quick freezing method and slow freezing method as long as the water in the solid food can be frozen.

  In addition, when solid food after freezing and liquid food are mixed to make a solid-liquid mixed food, the solid food after freezing will be completely thawed even if mixed with liquid food in the frozen state. You may mix. In addition, when the frozen solid-liquid mixed food is Joule-heated, the frozen solid-liquid mixed food may be Joule-heated in a frozen state or Joule-heated after being completely thawed. Therefore, the state of the solid food or the solid-liquid mixed food when moving from freezing to the next step is not particularly limited. Thawing may be performed in any of solid, gas, and liquid, and the thawing method is not particularly limited. Further, when thawing, gas, liquid, or solid may be heated to promote thawing. Further, the temperature for thawing is not particularly limited.

  The mixing of the solid food and the liquid food used in the present invention means that the solid food and the liquid food are present together. The state in which the solid food and the liquid food are present together may be a state in which the solid food and the liquid food are present together in a part or a state in which the food is present together, but the effect of the present invention is sufficiently obtained. In order to obtain, it is preferable that it exists in the whole together.

  The method of mixing the solid food and the liquid food used in the present invention is not particularly limited as long as the solid food and the liquid food are in a state where they exist together. For example, the method of simply mixing the two or the liquid food The method of immersing in food is mentioned. Here, immersing the solid food in the liquid food means immersing the solid food in the liquid food.

  The mixing ratio of the solid food and the liquid food used in the present invention is not particularly limited, but the amount of the liquid food is the minimum necessary for energizing and preventing excessive heating during energization. Must be present in quantity. Note that the minimum necessary amount varies depending on the energization device that performs Joule heating. Moreover, the temperature at the time of mixing will not be specifically limited if it is the temperature which does not impair the quality of a foodstuff.

When the mixing used in the present invention is immersion, the time during which the solid food is immersed in the liquid food is not particularly limited. The temperature at the time of immersion is not particularly limited as long as it does not impair the quality of the food.
If the immersion is performed not only for mixing the solid food and the liquid food but also for the purpose of penetrating the liquid food into the solid food, it is preferably immersed under heating in order to promote the penetration. Moreover, you may implement under pressure. The immersion under heating may be performed by immersing the solid food in the heated liquid food or by heating from the outside during the immersion.

  When a solid food is immersed in a heated liquid food or heated from the outside during the immersion, the heating temperature may be any temperature that promotes the penetration of the liquid food into the solid food. 30 to 100 ° C, preferably 60 to 100 ° C, more preferably 100 ° C. However, the heating temperature needs to be determined for each food because it is necessary to take into account the boiling and discoloration of the food. It is well known to those skilled in the art that the heating time varies arbitrarily depending on the heating temperature, the type, size or amount of solid food, the type or amount of liquid food, temperature or pressure, and the like. There is no particular limitation as long as it takes time to penetrate the solid food.

  In immersion, when solid food is heated to room temperature (15-30 ° C) or higher, when the heated solid-liquid mixed food is frozen or when Joule heating is performed, it can be frozen in a heated state or Joule heated. Alternatively, it may be frozen after cooling to room temperature or Joule heated. Therefore, the temperature of the solid / liquid mixed food when the heated solid / liquid mixed food is transferred to the next step is not particularly limited. Cooling may be performed in any of solid, gas, and liquid, and the cooling method is not particularly limited. Further, during the cooling process, gas, liquid, and solid may be cooled in order to promote cooling. The temperature for cooling is not particularly limited.

  In addition, even when the mixing used in the present invention is not just immersion but merely mixing solid food and liquid food, penetration of liquid food into the solid food can occur as in the case of immersion. That is, when solid food and liquid food after freezing are mixed, the liquid food penetrates into the solid food during joule heating, and when frozen by mixing solid food and liquid food, During the thawing process and subsequent Joule heating, the liquid food penetrates into the solid food.

The joule heating of the food used in the present invention means heating the food by using heat generated by electric resistance (joule heat) generated by energizing the food, that is, passing electricity to the food. Joule heating of a mixed food means heating by supplying electricity to a mixed food (solid-liquid mixed food) composed of a solid food and a liquid food.
Therefore, the method for producing a solid-liquid mixed food of the present invention is characterized in that Joule heating is applied to a solid-liquid mixed food containing a solid food having a freezing history as described above. It may be before or after mixing the liquid food. Note that the operation of starting the mixing of the solid food and the liquid food simultaneously with the start of the freezing also occurs because the state in which the solid food and the liquid food exist together occurs prior to the freezing of the solid food and the liquid food. The solid food and liquid food are mixed and then frozen to be included in the process of obtaining the solid-liquid mixed food. Here, the solid food having a freezing history means a solid food having experience of being frozen in the past. In addition, the heating temperature obtained by Joule heating in the present invention and the heating time of Joule heating are not particularly limited. Therefore, the purpose of the Joule heating of the present invention is not particularly limited, and may be simply heating of the solid-liquid mixed food, for cooking, for sterilization, or for sterilization.

  The energization for the Joule heating of the food used in the present invention may be any alternating current as long as it generates Joule heat, but usually an alternating current of commercial frequency is preferably used. It is well known to those skilled in the art that the applied voltage and current value are determined according to the electrical conductivity of the food and the target temperature. An apparatus for joule heating may be manufactured by itself or obtained from the market. An apparatus for joule heating available from the market includes a pressurized chamber type joule heating apparatus (Frontier Co., Ltd.). Engineering), Joule type applicator (manufactured by Izumi Food Machinery Co., Ltd.), and the like.

The solid-liquid mixed food used in the present invention is sterilized by Joule heating. The solid-liquid mixed food is Joule-heated, and the fungus in the food described in "General Food Dictionary 6th Edition" This means that the number is reduced to a problem-free range according to the purpose.
Sterilization of the solid / liquid mixed food used in the present invention by Joule heating means that the solid / liquid mixed food is Joule heated and described in “General Food Dictionary 6th Edition” It means to kill all the microorganisms attached to the.

Verification of Prior Art In Comparative Examples 1 to 3, the effect of heat treatment (Patent Documents 6 and 7) in an electrolyte solution on the Joule heating method in a solid-liquid mixed food is verified.

Comparative Example 1
[Verification of variation by type of solid food]
Experimental method Joule heating device A pressurized chamber type Joule heating device (manufactured by Frontier Engineering Co., Ltd.) was used. This apparatus is composed of a high frequency power supply (frequency fixed at 20 KHZ), a water tank electrode type joule heating device (inside container dimensions: 100 mm × 100 mm × 100 mm) and a pressurized chamber.

Preparation of Sample As a known pretreatment method, Patent Document 7 (Japanese Patent Publication No. 7-34720) in which boil treatment is performed in an electrolyte solution was referred to. The solid food material was cut into a predetermined size (20 mm or 30 mm) and boiled for 10 minutes in 1.2% NaCl solution as an electrolyte solution. After cooling the treated solid food material (25 ° C.), it is mixed with 0.6% NaCl solution as a liquid food material at a certain ratio (solid: liquid = 1: 11, 1: 6 or 1: 2) A heated sample was used.

Operating conditions After the sample was filled to the fixed position of the water tank electrode (position 2 mm below the upper end of the container) according to the instruction manual of the apparatus, the whole chamber was energized at a constant voltage of 100 V while being pressurized with a pressure of 0.25 Mpa. Subsequent energization control was performed by automatic control so that the temperature of the liquid portion was maintained at 121.1 ° C.

Temperature measurement In order to observe the temperature course of the solid part and the liquid part, the temperature sensor attached to the pressurized chamber type Joule heating device was installed in each of the solid part and the liquid part, and the temperature was continuously measured.

Measurement of electrical resistivity (ρ) A needle-shaped (1.5 mm diameter) platinum electrode is inserted into the food material so that the distance between the anode and the cathode is 10 mm, a constant current of 80 mA is passed, and the voltage between the electrodes is measured. Thus, the resistance value was obtained. Furthermore, the electrical resistivity (ρ) was obtained by the following equation.
Electric resistivity (ρ) = resistance value × electrode area / distance between electrodes

Experimental Results Carrots, radishes, potatoes and beef were cut into dies with sides of 20 mm and 30 mm. A boil treatment was performed in a 1.2% NaCl solution, followed by Joule heating. The solid-liquid ratio was 1:11.
As a result, a significant difference was observed in the temperature rise due to Joule heating due to the difference in the type of solid food (see FIG. 1).

  In addition, depending on the type of solid food, the effect of the cut size is different. For carrots, radishes, and beef, the smaller the size, the faster the temperature rise, but for potatoes the effect of size was relatively small (Fig. 2). reference).

  Furthermore, the relationship between the change in electrical resistivity before and after the boil treatment for each type of solid food and the Joule heating rise temperature is shown in Table 1, FIG. 3, and FIG.

  From FIG. 3, the electrical resistivity of vegetables was decreased by the boil treatment with the electrolyte solution, but the electrical resistivity was increased in the case of beef. In the case of meat, it was thought that the boil treatment caused the meat tissue to shrink, which increased the electrical resistivity. Moreover, the variation in electrical resistivity before and after the boil treatment was the same for both vegetables and meat, and in particular, no improvement in variation (small variation) was observed.

Furthermore, as shown in FIG. 4, a very significant negative correlation was recognized between vegetables and meats between the electrical resistivity after boil treatment and the elevated temperature due to Joule heating. However, the regression coefficients were clearly different between vegetables and beef, suggesting that vegetables are more susceptible to electrical resistivity.
As described above, a large difference was observed in the temperature rise characteristics by Joule heating depending on the type of solid food.

Comparative Example 2
[Verification of variation due to differences in individuals and parts]
In order to verify the variation in more detail, we examined carrots, which are considered to be the most susceptible to variations. An upper part or an intermediate part of one carrot was cut into a die having a side of 30 mm, and the carrot with the part distinguished was subjected to a boil treatment in an electrolyte solution as in Comparative Example 1, followed by Joule heating. The solid-liquid ratio was 1: 6. This experiment was repeated seven times, and the degree of variation due to the difference between individuals and the difference between the sites was verified.

As a result, a significant difference was observed between individuals and sites in the electrical resistivity after boiling treatment and the temperature increase due to Joule heating (see Table 2 and FIG. 5). In addition, the electrical resistivity of the raw carrot before the boil treatment was about 3.3 to 3.8 with no significant difference between the upper part and the middle part.
Moreover, as a result of verifying the relationship between the electrical resistivity of the raw material portion after the boil treatment and the temperature rise due to the Joule heating treatment, a large negative correlation was found between them (see FIG. 6).
As described above, the electrical resistivity before and after the boil treatment was almost the same between individuals and parts, but after the boil treatment, the electrical resistivity greatly varies, which causes uneven heating. Was confirmed.

Comparative Example 3
[Verification of variation by raw material size]
Using the carrot middle part, it was cut into dies with sides of 10 mm, 15 mm, 20 mm and 30 mm. The electrical resistivity of the raw carrot was 3.3. After performing the boil treatment in the electrolyte solution as in Comparative Example 1, Joule heating was performed. The solid-liquid ratio was 1: 2.

As a result, due to the difference in carrot size, a significant difference was found in the electrical resistivity after boiling treatment in the electrolyte solution and the temperature rise due to Joule heating (see Table 3, FIG. 7, FIG. 8, FIG. 9). .
Moreover, as a result of verifying the relationship between the electrical resistivity of the raw material after the boil treatment and the temperature rise due to the Joule heating treatment, a large negative correlation was found between them (see FIG. 10).
As described above, the electrical resistivity was 3.3, which was almost equal before the boil treatment, but the electrical resistivity was different after the boil treatment, and there was a large difference between the carrot cut size and the electrical resistivity. A positive correlation was observed, and it was confirmed that the cut size of carrot had an effect on the variation in elevated temperature during Joule heating.

Problems of Joule Heating of Solid-Liquid Mixed Food by Conventional Heat Treatment Method Obtained from Results of Comparative Examples 1 to 3 <1> Solid foods each have a specific electrical resistivity.
<2> Depending on the solid food, there is structural non-uniformity, so the electrical resistivity varies depending on the part.
<3> Depending on the solid food, the tissue structure changes with heating, so the electrical resistivity also changes.
<4> Depending on the solid food, the size of the solid food is greatly affected by the size of the electrolyte solution treatment, which causes variations in electrical resistivity.
<5> The electrical resistivity of the solid food has a large negative correlation with the temperature rise characteristic of Joule heating. Therefore, in the Joule heating of the solid-liquid mixed system, the temperature rise characteristics of the individual food materials are different, and the heating history varies to the extent that it becomes a practical problem.
Therefore, in the conventional heat treatment method, due to non-uniform heating, due to the inherent electrical conductivity of the solid food, due to individual differences in the solid food, due to structural heterogeneity at each solid food part, or due to heating of the tissue structure It cannot be said that the variation in the electrical resistivity of solid food due to changes or the like has been sufficiently eliminated in practice.

  Next, the present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

[Effect of freezing and boiling on electrical resistivity]
The carrot site was not particularly selected, and was cut into dies having a prescribed size (20 mm, 30 mm). Cut carrots were randomly divided into frozen and untreated groups. The freezing process was performed by cooling in a freezer at −40 ° C. for 12 hours. Thereafter, the frozen carrots were boiled in 1.2% NaCl solution for 10 minutes in the same manner as in Comparative Example 1, and the electrical resistivity of each was measured. The results are shown in Table 4. The variation is expressed as a coefficient of variation.

  Compared to the electrical resistivity of raw carrots, it was again confirmed that the carrot group that had been boiled in the electrolyte solution without being subjected to refrigeration was greatly affected by size, although the electrical resistivity decreased. It was. It was also confirmed that the coefficient of variation, which is an index indicating the variation, was not improved as compared with raw carrots. On the other hand, it was confirmed that the group that had been subjected to the boil treatment in the electrolyte solution after the refrigeration treatment had a lower electrical resistivity, and the influence of the size and the site was small. Also, the coefficient of variation was greatly improved compared to raw carrots.

[Effect of process change on electrical resistivity]
Next, the process conditions before and after the freezing process in the carrot process were changed and the effect was confirmed. The measurement of electrical resistivity is the same as in Comparative Example 1. The results are shown in Table 5.

Treatment method A; Freezing → Immediately boil treatment in electrolyte solution → Water cooling (1 minute)
B: Freezing → Thaw at room temperature → Boil treatment in electrolyte solution → Water cooling (1 minute)
C: Freezing → Thawing in running water → Boil treatment in electrolyte solution → Water cooling (1 minute)
D: Branching treatment (90 ° C., 3 minutes) → Freezing → Boil treatment in electrolyte solution → Water cooling (1 minute)

  In processes A, B and D, a large effect of freezing treatment was recognized. In the process C, the effect of the freezing treatment was recognized, but the degree of the effect was small compared to the previous three processes A, B and D.

[Effect of freezing and immersion treatment on electrical resistivity]
Instead of the boil treatment in the electrolyte solution, the electrolyte solution treatment condition was a dipping treatment at room temperature, and the effect of the freezing treatment was verified.

The carrot site was not particularly selected and was cut into dies of a prescribed size. Cut carrots were randomly divided into frozen and untreated groups. The freezing process was performed by cooling in a freezer at −40 ° C. for 12 hours. Each group was immersed in a 1.2% NaCl solution, and the electrical resistivity was measured at regular intervals to evaluate the permeability of the electrolyte solution. The start (0 hour) in Table 6 means a raw carrot or a carrot after thawing, which is not immersed in a 1.2% NaCl solution. The immersion temperature was about 25 ° C. Furthermore, for the frozen processed product, after being immersed for 2 hours, Joule heat treatment was performed in a state where the mixing ratio of the carrot after immersion and the 0.6% NaCl solution as the liquid food material was 1:11 or 1: 6, and the freezing treatment was performed. The effect was confirmed.
The measurement results of electrical resistivity are shown in Table 6 and FIG.

  From the above results, it was confirmed that the carrots subjected to the freezing treatment rapidly decreased in electrical resistivity by the soaking treatment, and the variation became small, and reached a plateau at the time of soaking for 2 hours. On the other hand, the electrical resistivity of the carrots not subjected to the freezing treatment hardly decreased even when immersed for 8 hours.

  Further, the frozen carrot was soaked for 2 hours, and then subjected to Joule heat treatment. The temperature of two specimens was measured for each of the 20 mm die and the 30 mm die, but the results showed little variation, and an extremely uniform temperature increase and F value increase could be confirmed. The results are shown in FIG. In particular, at the temperature of FIG. 12, two specimens of 20 mm dice and two specimens of 30 mm dice are shown, but each overlaps one line.

  As described above, in the combination of the freezing process and the dipping process, as in the case of the combination of the freezing process and the boil process, a decrease in electrical resistivity and a uniform electrical resistance value could be obtained. From this result, regarding the electrical resistivity, the effect of the freezing treatment of the material is obvious, and the freezing treatment at the room temperature immersion treatment of this example is more than the difference between the freezing treatment at the time of boiling treatment of Example 1 and the case of no treatment. There was a further marked difference in the presence or absence of. As a result, it was confirmed that extremely uniform heating could be performed in the subsequent Joule heating.

[Effect of order of refrigeration during pretreatment process on electrical resistivity and Joule heating]
Next, in Examples 1 to 3, since the boil treatment or the immersion treatment was performed after the freezing treatment, and the effect on the electrical resistivity and Joule heating was confirmed, in this embodiment, the order of the pretreatment process before energization, It changed into the order which performs a freezing process after performing a boil process or an immersion process, and confirmed the effect on an electrical resistivity and a Joule heating.

The carrot site was not particularly selected and was cut into a 20 mm size die. The cut carrot was boiled with 1.2% NaCl solution for 10 minutes as an electrolytic solution treatment, and then subjected to a freezing treatment. The freezing process was performed by cooling in a freezer at −40 ° C. for 12 hours. The treated carrots were thawed and then mixed with a 0.6% NaCl solution as a liquid food material at a ratio of 1:11 to prepare a Joule-heated sample. The following experiment was performed as a control.
Control 1 (frozen → boiled); Joule heated control 2 (boil only) of sample boiled for 10 minutes with 1.2% NaCl solution after freezing; sample boiled for 10 minutes with 1.2% NaCl solution Joule heating control 3: untreated (raw carrot) joule heating

  Table 7 shows the measurement results of four samples for each experiment. In order to evaluate the variation associated with each treatment, the electrical resistivity is used as an index before Joule heating, the temperature rises when Joule heating is performed for 4 minutes as an index during temperature rise, and the F value during 6 minutes heating is used as an index for cumulative heating history. Adopted. The F value is the heating time (minutes) required to kill a certain concentration of microorganisms at a constant temperature, and is usually the heating lethal time at 121.1 ° C.

The above results are summarized as follows.
In the coefficient of variation indicating the variation in electrical resistivity measured before Joule heating, the test product (boil treatment → freezing treatment, 0.08) was smaller than control 3 (raw, 0.13), but control 1 (freezing treatment). → Boil treatment, larger than 0.04) and similar to Control 2 (only boil treatment, 0.07).

  However, as for the variation (coefficient of variation) in temperature rise during Joule heating, the test product (boil treatment → freezing treatment, 0.04) is comparable to the control 1 (freezing treatment → boil treatment, 0.04), It was slightly less than controls 2 (boil treatment only, 0.07) and 3 (raw, 0.06).

  As for the F value variation (coefficient of variation), which is a cumulative index of Joule heating, the test product (boil treatment → freezing treatment, 0.37) is from Control 1 (freezing treatment → boil treatment, 0.24). Although slightly larger, it was clearly smaller than controls 2 (boil treatment only, 0.85) and 3 (raw, 0.73).

Furthermore, FIG. 13 shows a comparison of the temperature rise and F value over time between the test product (boil treatment → freezing treatment) and control 2 (only boil treatment). As shown in FIG. 13, even when observed over time, the test product (FIG. 13 (A); boil treatment → freeze treatment) has less variation than Control 2 (FIG. 13 (B); boil treatment only). It could be confirmed. In particular, in the F value of FIG. 13C, it can be seen that the four lines of the test product (freezing process after the electrolyte solution treatment) are smaller in variation than the four lines of the control 2 (only the electrolyte solution treatment). .
From this, it was confirmed that the order of the freezing treatment was effective before or after the boil treatment.

  In addition, even when the electrolyte solution treatment is not the boil treatment but the immersion treatment shown in Example 3 (freezing treatment → dipping treatment), the dipping treatment is performed before the freezing treatment as in the case of the boil treatment in this experiment. Even so, it is clear that it is effective. However, when the immersion treatment is performed before the freezing treatment (immersion treatment → freezing treatment), it may be necessary for those skilled in the art to change the immersion time shown in Example 3 (freezing treatment → immersion treatment). Obviously.

[Effect of freezing treatment for various solid foods on electrical resistivity and Joule heating]
As described above, a new finding has been obtained that the electrical resistivity of a solid food can be made uniform by performing a freezing treatment and a boil treatment or an immersion treatment with an electrolyte solution. Therefore, the effect on various solid foods was verified.

  In particular, carrots, radishes, potatoes and beef were cut into dies with sides of 20 mm and 30 mm without selecting the parts. After the freezing process in process A, Joule heating was performed and compared with the unprocessed (no freezing process) data. The solid-liquid ratio was 1:11. As a result, it was confirmed that by performing the freezing treatment, the electrical resistivity was lowered and the variation in electrical resistivity depending on the type and size of the solid food was obviously reduced. (See Table 8).

  That is, by performing the boil treatment with the electrolyte solution after the freezing treatment, faster uniform heating was expected in the subsequent Joule heating step. In fact, as a result of Joule heating, it was confirmed that the variation in temperature rise due to the type of solid food was clearly reduced (see FIG. 14).

  In the experiment without freezing treatment (untreated), although there was a difference in the degree depending on the type of solid food, it was affected by the cut size, and the smaller the size, the faster the temperature rise was observed (FIG. 15). Inside untreated). It was confirmed that the refrigeration treatment was effective even for variations in size (freezing in FIG. 15). The temperature rise pattern and F value data are shown in FIG.

The method of the present invention makes it possible to use the Joule heating method for a solid-liquid mixed food comprising a solid food and a liquid food.
By the method of the present invention, it is possible to produce a high-quality food (heat-sterilized or heat-sterilized food) having a rich variety of flavors while maintaining the original flavor and color tone instead of retort heating.

Comparison of heating characteristics by type of solid food. The relationship between the energization time and the temperature rise when a solid food (carrot, daiko, potato, beef) cut into 30 mm dies is boil heated in an electrolyte solution and then Joule heated is shown. Relationship between cut size and joule heating temperature rise by type of solid food. The relationship between the energization time and the temperature rise for each solid food when a solid food (carrot, daiko, potato, beef) cut into 20 mm or 30 mm dies is boil heated in an electrolyte solution and then Joule heated is shown. Comparison of electrical resistivity before and after boiling heat treatment in electrolyte solution according to the type of solid food. The electrical resistivity before heat treatment of the solid food (carrot, daiko, potato, beef) cut into 20 mm or 30 mm dies shown in Table 1 and the electrical resistivity after boiling the solid food in an electrolyte solution The relationship is shown. Relationship between electrical resistivity and temperature rise after boiling heat treatment in electrolyte solution. Electric resistivity after boiling heat treatment in electrolyte solution of solid food (carrot, daiko, potato, beef) cut into 20mm or 30mm dice shown in Table 1 and temperature increase due to Joule heating (° C / 4 min energization) Shows the relationship. Variation due to differences in individuals and parts. The relationship between the energization time and the temperature rise in Joule heating after the upper part or middle part of the carrot cut into 30 mm dies is subjected to the boil heating treatment in the electrolyte solution is shown for each individual. The relationship between the electrical resistivity of the raw material parts and the temperature rise. The relationship between the electrical resistivity after boiling heat processing in the electrolyte solution for every number of experiment shown in Table 2, and the temperature rise (degreeC / 4-minute energization) by Joule heating is shown. The effect of carrot size. The relationship between the energization time and temperature rise in Joule heating after carrying out the boil heating process in the electrolyte solution for the intermediate part of the carrot cut into 10 mm, 15 mm, 20 mm, and 30 mm dice is shown. Relationship between carrot size and electrical resistivity. The relationship between the electrical resistivity after carrying out the boil heat processing of the intermediate part of the carrot cut to 10 mm, 15 mm, 20 mm, and 30 mm dice | dies shown in Table 3 in an electrolyte solution, and the cut size of a carrot is shown. The relationship between carrot size and temperature rise. The temperature rise in Joule heating after energizing the middle part of the carrots cut into 10 mm, 15 mm, 20 mm, and 30 mm dies shown in Table 3 in the electrolyte solution (energization for 4 minutes) and the cut size of the carrot Show the relationship. Relationship between electrical resistivity and temperature rise. Relationship between electrical resistivity after boiling heat treatment of carrots cut into 10mm, 15mm, 20mm and 30mm dies shown in Table 3 in an electrolyte solution and temperature rise due to Joule heating (° C / 4 min energization) Indicates. Change over time of electrical resistivity when immersed in electrolyte solution. The relationship between the average value of electrical resistivity of Table 6 and the immersion time is shown. Confirmation of freezing treatment effect. A sample obtained by immersing the frozen carrot for 2 hours was subjected to Joule heat treatment. Two samples were measured for each of the 20 mm die and the 30 mm die. In the case of a 20 mm die, the solid-liquid ratio is 1:11, and in the case of a 30 mm die, it is 1: 6. The time-dependent change of the measured temperature (A) and F value (B) is shown. Comparison of temperature and F value over time of Joule heating of carrot (test product) subjected to freezing treatment after boiling treatment in electrolyte solution and carrot treated only with boiling treatment in electrolyte solution (control 2). The time-dependent changes in the temperature and F value of the test product ((A); boil treatment → freezing treatment) and control 2 ((B); boil treatment only) in Table 7 are shown. Effect of freezing treatment on variation due to the type of solid food. Energization time and temperature rise when solid food (carrot, daiko, potato, beef) cut into 30mm dies is boiled and heated in an electrolyte solution and then subjected to freezing and joule heating or without freezing Shows the relationship. Effect of freezing treatment on the variation in type or size of solid food. When solid food (carrot, daiko, potato, beef) cut into 20 mm or 30 mm dies is frozen and then boiled in an electrolyte solution and joule heated or after boiled and heated in an electrolyte solution without freezing In the case of Joule heating, the relationship between energization time and temperature rise (A1, B1, C1, D1) or the relationship between energization time and F value (A2, B2, C2, D2) is shown for each type of solid food. .

Claims (3)

(A1) a step of freezing the solid food, and then mixing the liquid with a liquid food without thawing or thawing, or (a2) mixing the solid food with the liquid food and then freezing it To obtain a solid-liquid mixed food,
And (b) a method for producing a solid-liquid mixed food, comprising a step of joule heating the solid-liquid mixed food.   The method for producing a solid-liquid mixed food according to claim 1, wherein the solid-liquid mixed food is sterilized or sterilized by the step (b).   The solid-liquid mixed food obtained by the manufacturing method of the solid-liquid mixed food of Claim 1 or Claim 2.