JP2016067262A - Radiation sterilization method for packed fresh meat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation sterilization method for fresh meat, by which deterioration of fresh meat taste and generation of nasty smell by radiation sterilization can be suppressed to provide meat for eating raw which is improved in flavor.SOLUTION: The radiation sterilization method for packed fresh meat includes: a filling process for filling fresh meat and edible oil into a container; a sealing process for degassing and sealing the container filled with the fresh meat and the edible oil to provide a packed fresh meat; a cooling process for freezing the packed fresh meat; and a sterilization process for sterilizing the packed fresh meat by irradiating γ rays while the packed fresh meat is frozen.SELECTED DRAWING: None

Description

  The present invention relates to a method for sterilizing raw meat filled in a container by γ-ray irradiation.

  At present, when meat is eaten as raw meat without heating, it is necessary to perform a heat sterilization treatment at 60 ° C. for 2 minutes. However, since such a heat sterilization process loses the flavor and texture of raw meat, a sterilization method other than heating is required. As one of them, a sterilization method using radiation has been studied. However, when irradiating a high dose of γ-rays to sterilize raw meat, there are problems such as generation of off-flavors, deterioration of color tone, and deterioration of taste.

  For example, Non-Patent Document 1 discloses that when meat or the like is sterilized by radiation, the taste is lowered or a strange odor is generated. Non-Patent Document 1 discloses methods such as oxygen-free packaging and freezing irradiation in order to prevent a decrease in taste.

  Patent Document 1 discloses a problem that odor is generated from a food packaging material by irradiating food with radiation, and a packaging material that does not easily generate odor even when irradiated with radiation is disclosed. Yes.

  However, these methods are not sufficient in suppressing the generation of off-flavors, the deterioration of color tone, the decrease in taste, and the like, and are insufficient for providing meat suitable for raw food.

JP 2010-159398 A

Hitoshi Ito, “Technology for preventing and reducing the taste of meat by radiation” [online], September 22, 2003, Radiation Utilization Promotion Association, Radiation Utilization Technology Database, Internet <URL: http: //www.rada. or.jp/database/home4/normal/ht-docs/member/detail/020230.html>

  It is an object of the present invention to provide a raw meat radiation sterilization method capable of providing raw edible meat with improved flavor by suppressing the generation of off-flavors, deterioration of color tone, deterioration in taste, and the like due to radiation sterilization.

  According to the present invention, a filling step for filling a container with raw meat and edible oil, a sealing step for obtaining container-packed raw meat by degassing and sealing the container filled with the raw meat and edible oil, and the container A radiation sterilization method for container-packed raw meat comprising a cooling step of freezing stuffed raw meat and a sterilization step of sterilizing the container-packed raw meat by irradiating γ-rays in a frozen state.

  According to the method of the present invention, it is possible to provide raw meat with improved flavor properties by suppressing the generation of off-flavors due to radiation sterilization, deterioration of color tone, deterioration of taste, and the like.

  Embodiments of the present invention will be described. A method for radiation sterilization of raw meat in a container according to the present invention includes a filling step of filling a container with raw meat and edible oil, and degassing and sealing the container filled with the raw meat and edible oil to obtain raw stuffed container A sealing step, a cooling step of freezing the container-packed raw meat, and a sterilization step of sterilizing the container-packed raw meat by irradiating with γ rays in a frozen state.

  The raw meat targeted by the sterilization method of the present invention is not particularly limited, and includes beef, pork, chicken, horse meat, and other organs such as liver. The raw meat may be any form of meat such as minced meat, block meat, sliced meat, and minced meat.

  The edible oil may be any oil as long as it is used for food. For example, salad oil, rice oil, sesame oil, olive oil, ben flower oil, corn oil and the like are used. More preferably, an edible oil selected from olive oil, sesame oil, salad oil and rice oil is used. Since olive oil and sesame oil are particularly resistant to high doses of gamma rays, it is particularly preferred to use an edible oil selected from olive oil and sesame oil. Moreover, since olive oil and sesame oil have a relatively strong scent, the flavor can be further improved by adding the scent to raw meat. Moreover, even when a slight odor is generated from raw meat or a container by irradiating a high dose of γ rays, the odor can be masked by the scent of olive oil or sesame oil.

  If the container used by the method of this invention can seal raw meat and edible oil, the kind and form will not be specifically limited. For example, a can container and a flexible packaging container can be used.

  The material of the can container is not limited to these, but stainless steel, aluminum, copper and the like can be used. The metal can may be a can made of only metal, but may be a resin-coated can.

  As the flexible packaging container, for example, a pouch container for retort pouch packaging can be used. Examples of the pouch container include a metal-made pouch container such as aluminum, a resinous pouch container, a pouch container made of a composite material, a pouch container made of a film in which metal foil and a plastic film are laminated, and the like.

  The material used for the flexible packaging container and the resin used as the coating for the can container are not limited to these, but can be selected from polyethylene, polypropylene, epoxy, polyester, nylon, and the like.

  When a resin container is used, a slight odor may be generated by irradiating γ rays depending on the type of resin. Therefore, it is preferable to use a metal container. Since the metal container has a higher thermal conductivity than the resin container, the time required for freezing can be shortened in the step of freezing after filling the container with raw meat as will be described later. In addition, the time required for thawing the frozen container-packed raw meat can be shortened.

  In the filling step, the container is filled with raw meat and edible oil as described above. Subsequently, in the sealing step, the container filled with raw meat and edible oil is degassed and sealed to obtain raw meat packed in the container. Here, the raw meat packed in a container is, for example, canned raw meat or stuffed with a pouch. In this specification, it will be referred to as container-packed raw meat.

  The filling is performed so that the container is fully filled with raw meat and cooking oil, and no space in which air can exist is left in the container. After filling, deaeration and sealing can be performed without leaving air in the container. Thereby, the influence of oxygen can be made small and generation | occurrence | production of a strange odor can be suppressed when a radiation is irradiated.

  In the filling step and the sealing step, it is preferable to form an edible oil layer on the surface of the raw meat filled in the container and seal it. Since the surface of the raw meat is covered with the edible oil layer, contact between the air and the raw meat can be blocked even when a small amount of air is present in the container. Thereby, the influence of oxygen can be made small and generation | occurrence | production of a strange odor can be suppressed when a radiation is irradiated.

  Examples of a method for forming a layer of edible oil on the surface of raw meat include a method of filling edible oil after filling the container with raw meat, and a method of filling the container after mixing raw meat and edible oil in advance. By filling the container with raw meat and then with edible oil, after filling, the edible oil travels along the raw meat surface to the bottom of the raw meat, and the whole raw meat can be covered with a layer of edible oil. Alternatively, the whole raw meat can be covered with a layer of edible oil by filling the container with raw meat and edible oil in advance. Furthermore, when a soft packaging container such as a pouch container is used, the whole raw meat can be covered with a layer of edible oil by filling the container with edible oil and then filling with raw meat. The flexible packaging container is in close contact with the raw meat in the deaeration process after filling. At that time, the edible oil also travels along the surface of the raw meat from the bottom to the top of the container, so that the whole raw meat can be covered with a layer of edible oil.

  Therefore, when a container is a can, it is preferable that a filling process is performed by accommodating a raw meat in a container and then filling with cooking oil. When the container is a soft packaging container such as a pouch container, any method may be used, but the container may be filled with edible oil and then filled with raw meat.

  Next, the container-packed raw meat is frozen by a cooling process. A conventionally well-known method can be used for the method of freezing the container-packed raw meat. For example, it may be rapidly frozen by dipping in liquid nitrogen. Or you may hold | maintain at about -20 degreeC to -60 degreeC in a freezer, and you may freeze. In the cooling step, the raw meat may be frozen, and the edible oil need not be frozen.

  Next, in the sterilization step, the packed raw meat in a frozen state is irradiated with γ rays. In this way, raw meat is sterilized. A generally used device can be used as the γ-ray irradiation device.

  The γ-ray irradiation is preferably performed so that the absorbed dose of raw meat is 1.5 kGy or more. The absorbed dose required to sterilize E. coli to below the detection limit differs depending on the number of E. coli held in raw meat before irradiation. By irradiating so that the absorbed dose is 1.5 kGy or more, Escherichia coli can be sterilized to the detection limit or less if the raw meat has a low contamination state. The general standard for irradiated foods formulated by the International Food Standards Committee sets the absorbed dose to 10 kGy or less in principle. In addition, even when raw meat with extremely high contamination is targeted for sterilization, Escherichia coli can be sterilized to the detection limit or less by setting the absorbed dose to about 5 kGy. Therefore, the absorbed dose is preferably 4 kGy or more, and more preferably 5 kGy or more.

  If the absorbed dose is too high, there is a risk of off-flavor generation from raw meat and packaging materials, and a decrease in texture and taste. Therefore, the absorbed dose is preferably 10 kGy or less. When sesame oil is used as edible oil, a good flavor can be obtained even if the absorbed dose is 10 kGy. When other edible oils are used, the absorbed dose is preferably 8 kGy or less, and more preferably 6 kGy or less.

  By the method including the steps described above, sterilized raw meat in a container can be obtained. According to the method of the present invention, radiation sterilization is possible without causing a change in color tone or flavor in raw meat. Therefore, it is possible to produce a raw meat product that is safe without being heated.

<Example 1>
Raw meat was subjected to a radiation sterilization test using the sterilization method of the present invention. Minced beef was used as raw meat. An aluminum can was used as the container.

1) Preparation of bacterial solution As an inoculum, Escherichia coli JCM18426 (O157: H7 toxin non-producing strain) was used. The inoculum was cultured at 35 ° C. for 24 hours on a Soybean Casein Digest agar medium (SCD agar medium: manufactured by Nippon Pharmaceutical). After culturing, the colony was suspended in sterilized phosphate buffered saline to prepare a bacterial solution.

2) Preparation of bacterial inoculation sample The ground beef was placed in a sterilized pouch bag, the bacterial solution was added so that the final concentration was about 107 CFU / g, and the mixture was sealed with a heat sealer. The mixture was mixed well so that the bacterial solution was uniform, the pouch bag was opened, and the aluminum can was filled to a total amount of 100 g.

  As Examples 1 to 9, 10 g of edible oil and 90 g of ground beef after the bacterial inoculation treatment were filled, and a total of 100 g was filled so as to be filled. As edible oils, Examples 1 and 2 used salad oil, Examples 3 and 4 used rice oil, Examples 5 and 6 used olive oil, and Examples 7 to 9 used sesame oil. In filling, the ground beef was first filled and then filled with edible oil so that a layer of edible oil was formed on the ground beef surface. Comparative Examples 1 to 3 were filled with 100 g of ground beef after the bacterial inoculation treatment without filling with edible oil.

  Each can was degassed after filling, and the can lid was wrapped and sealed. Then, it was immersed in liquid nitrogen at -196 ° C and quickly frozen.

3) Preparation of γ-ray irradiation sample A frozen sample was packed in a polystyrene foam box, further filled with dry ice, and irradiated with γ-rays while maintaining the sample temperature at -79 ° C. In the samples of Examples 1, 3, 5, and 7, the absorbed dose of γ rays was 3 kGy. In the samples of Examples 2, 4, 6, and 8, the absorbed dose of γ rays was 5 kGy. In the sample of Example 9, the absorbed dose of γ rays was 10 kGy. The sample of Comparative Example 1 was not irradiated with γ rays. In the sample of Comparative Example 2, the absorbed dose of γ rays was 3 kGy. In the sample of Comparative Example 3, the absorbed dose of γ rays was 5 kGy.

  The sample after γ-ray irradiation was thawed, and after opening the can, 25 g of the contents were weighed into a stomacher bag from the center of the container. 225 ml of sterilized phosphate buffered saline was added to the stomacher bag and sealed with a heat sealer. After stirring well, the stomacher bag was opened, 1 ml was serially diluted, mixed with XM-G agar medium (manufactured by Nissui Pharmaceutical), and cultured at 35 ° C. for 24 hours. All blue colonies were counted and measured as the number of coliforms (CFU / g). Moreover, about the color tone of the ground beef after opening a sample, the presence or absence of the change from the sample before gamma irradiation was determined visually. Moreover, the person who has the qualification of the odor judgment person based on the malodor prevention method was made into the panel, and the quality of the flavor of the ground beef after the sample was opened was judged.

4) Test results Table 1 shows the types of edible oils, the absorbed dose, the number of coliform bacteria, the color tone, and the observation results of flavor.

  In any of Examples 1 to 9, the number of coliform bacteria decreased as compared with Comparative Example 1 in which γ rays were not irradiated. Therefore, the bactericidal effect by gamma irradiation was recognized. In addition, the number of bacteria decreased as the absorbed dose increased, and in Examples 2, 4, 6, 8, and 9 where the absorbed dose was 5 kGy or more, the number of bacteria was below the detection limit.

  In all of Examples 1 to 9, there was no change in color tone, and a good appearance of ground beef was maintained. Also, there was no change in flavor and no off-flavor was generated. In Examples 5 and 6 to which olive oil was added and Examples 7 to 9 to which sesame oil was added, it was confirmed that a good scent of olive oil or sesame oil was added to ground beef and the flavor was improved.

  In Comparative Examples 2 and 3 to which edible oil was not added, the number of bacteria was reduced and a bactericidal effect was observed, but the color changed to brown and the generation of off-flavor was also observed. As a result of analyzing these samples by gas chromatography mass spectrometry, it was found that aldehyde was generated. Therefore, it was considered that the cause of off-flavor was aldehyde.

<Example 2>
Raw meat was subjected to a radiation sterilization test using the sterilization method of the present invention. Pork liver was used as raw meat. A polyethylene pouch container was used as the container.

1) Preparation of Bacterial Solution As an inoculum, Escherichia coli JCM18426 (O157: H7 toxin non-producing strain) was used in the same manner as in Example 1. The inoculum was cultured at 35 ° C. for 24 hours on a Soybean Casein Digest agar medium (SCD agar medium: manufactured by Nippon Pharmaceutical). After culturing, the colony was suspended in sterilized phosphate buffered saline to prepare a bacterial solution.

2) Preparation of bacterial inoculation sample Bacterial fluid was inoculated at multiple locations on the pig liver using a syringe. Inoculation was performed so that the final concentration of the bacterial solution was about 107 CFU / g. The inoculation was carried out so that the number of bacteria at each inoculation site was constant and the inoculation site was evenly distributed. The pork liver inoculated with the bacterial solution was filled in a pouch container so that the total amount was 100 g.

  In Examples 10 to 18, 10 g of edible oil and 90 g of pig liver after inoculation treatment were filled, and the total amount was 100 g. As edible oils, Examples 10 and 11 used salad oil, Examples 12 and 13 used rice oil, Examples 14 and 15 used olive oil, and Examples 16 to 18 used sesame oil. The pouch container was first filled with pork liver and then edible oil. Comparative Examples 4 to 6 were filled with 100 g of pig liver after bacterial inoculation without filling with edible oil.

  Each pouch container was degassed after filling and sealed with a heat sealer. Then, it was immersed in liquid nitrogen at -196 ° C and quickly frozen.

3) Preparation of γ-ray irradiation sample A frozen sample was packed in a polystyrene foam box, further filled with dry ice, and irradiated with γ-rays while maintaining the sample temperature at -79 ° C. In the samples of Examples 10, 12, 14, and 16, the absorbed dose of γ rays was 3 kGy. In the samples of Examples 11, 13, 15, and 17, the absorbed dose of γ rays was 5 kGy. In the sample of Example 18, the absorbed dose of γ rays was 10 kGy. The sample of Comparative Example 4 was not irradiated with γ rays. In the sample of Comparative Example 5, the absorbed dose of γ rays was 3 kGy. In the sample of Comparative Example 6, the absorbed dose of γ rays was 5 kGy.

  The sample after γ-ray irradiation was thawed and opened, and then 25 g of the contents were weighed into a stomacher bag from the center of the container. 225 ml of sterilized phosphate buffered saline was added to the stomacher bag and sealed with a heat sealer. After crushing and stirring well, the stomacher bag was opened, 1 ml was serially diluted, mixed with XM-G agar medium (manufactured by Nissui Pharmaceutical), and cultured at 35 ° C. for 24 hours. All blue colonies were counted and measured as the number of coliforms (CFU / g). Moreover, about the color tone of the pig liver after opening a sample, the presence or absence of the change from the sample before gamma ray irradiation was determined visually. Moreover, the person who has the qualification of the odor judgment person based on the malodor prevention method was made into the panelist, and the quality of the flavor of the pig liver after opening a sample was determined.

4) Test results Table 2 shows the types of edible oils, absorbed dose, coliform bacteria count, color tone, and flavor observation results.

  In all of Examples 10 to 18, the number of bacteria in the coliform group was reduced as compared with Comparative Example 4 in which γ rays were not irradiated. Therefore, the bactericidal effect by gamma irradiation was recognized. Moreover, the number of bacteria decreased as the absorbed dose increased, and in Examples 11, 13, 15, 17, and 18 where the absorbed dose was 5 kGy or more, the number of bacteria was below the detection limit.

  In all of Examples 10 to 18, there was no change in color tone, and a good appearance of the pig liver was maintained. Also, there was no change in flavor and no off-flavor was generated. In Examples 14 and 15 to which olive oil was added and Examples 16 to 18 to which sesame oil was added, it was confirmed that a good scent of olive oil or sesame oil was added to the pork liver and the flavor was improved.

  Even in Comparative Examples 5 and 6 in which no edible oil was added, the number of bacteria was reduced and a bactericidal effect was observed, but the color changed to brown and generation of off-flavor was also observed. As a result of analyzing these samples by gas chromatography mass spectrometry, it was found that aldehyde was generated. Therefore, it was considered that the cause of off-flavor was aldehyde.

Claims (5)

A filling step of filling the container with raw meat and cooking oil;
A sealing step of obtaining raw meat stuffed in a container by degassing and sealing the container filled with the raw meat and cooking oil,
A cooling step of freezing the container-packed raw meat;
A sterilization process for sterilizing the raw meat stuffed in the container by irradiating γ rays in a frozen state,
A method for radiation sterilization of raw meat in a container, comprising:   The method for radiation sterilization of raw meat in containers according to claim 1, wherein a layer of edible oil is formed and sealed on the surface of the raw meat filled.   The method for radiation sterilization of raw meat in containers according to any one of claims 1 to 2, wherein γ rays are irradiated so that the absorbed dose of the raw meat is 4 kGy or more.   The method for sterilizing raw stuffed meat in a container according to any one of claims 1 to 3, wherein the edible oil is at least one edible oil selected from the group consisting of olive oil, sesame oil, salad oil and rice oil. .   The said container is a can, The said filling process is performed by filling with edible oil after accommodating raw meat in the said container, The radiation sterilization method of the container-packed raw meat in any one of Claims 1-4.