JP2006275441A - Hydrogen gas-containing ice and its making method, and fresh food preserving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen gas-containing ice for keeping a reducing atmosphere for a long period even in an incompletely sealed container while preventing the decay of fresh fishes and suppressing the progress of discoloration, and to provide its making method and a fresh food preserving method. <P>SOLUTION: The method is provided for preserving fresh foods packaged with the hydrogen gas-containing ice in the container. The hydrogen gas-containing ice is made by icing after dissolving hydrogen gas or a mixture of hydrogen gas and inactive gas in raw material water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to hydrogen gas-containing ice suitable for preserving fresh food, a method for producing the ice, and a method for preserving fresh food using the ice.

  Conventionally, various methods have been proposed for maintaining the flavor of fresh foods, particularly fresh fish. The most common method is to keep the temperature low. Thereby, the growth of spoilage bacteria can be prevented and the freshness of fresh fish can be maintained. For transporting fresh foods, especially fresh fish, containers made of styrene foam called toro boxes are widely used. The Toro Box is inexpensive, has excellent heat retention and water resistance, and it is possible to keep the inside of the box at a low temperature by packing fresh fish and ice together in the Toro Box, and when fresh fish cannot be stored in the refrigerator or during transportation Can prevent rotting of fresh fish.

  However, the toro box is excellent in heat retention and water resistance, but is not necessarily sufficient in terms of airtightness. The Toro box is a molded product of granular foamed polystyrene resin, and there are a large number of gaps at the joint between the box body and the lid, so that it cannot be sufficiently blocked from the outside air. In Toro boxes that are not sufficiently blocked from the outside air (atmosphere), the flavor of fresh fish may be impaired for reasons other than bacterial decay. This is because oxygen contained in the atmosphere oxidizes chromoproteins such as myoglobin and hemoglobin in fresh fish to cause “methation”. Metolation not only worsens the flavor but also involves a visual “discoloration” and is therefore a more serious problem for fresh fish distributors.

Japanese Patent Application Laid-Open No. 2001-258468 discloses a method for storing fresh meat fresh fish in a container, wherein the standard redox potential of water adhering to the surface of the fresh fresh fish is -10 to 10 with a standard hydrogen electrode as a reference electrode. A method for preserving fresh meat fish of −1000 mV is disclosed. This fresh meat fresh fish preservation method is intended to suppress the progress of methation in a sealed container using the reducibility of hydrogen gas. Such a storage technique cannot be fully utilized in a toro box that causes oxygen contamination. In addition, there is a problem that a highly airtight container that completely blocks outside air increases the manufacturing cost and is not practical. On the other hand, Japanese Patent Application Laid-Open No. 10-267476 discloses a method for maintaining the freshness of a fresh food product over a long period of time by using synergistic effects of low-temperature storage and ozone sterilization power using block-shaped ozone-containing ice obtained by two-stage ice making. Is disclosed. However, ozone is a strong oxidant, and ice containing ozone gas may strongly promote the methodization (discoloration) of fresh fish. The commercial value of fresh fish, as mentioned above, is important to maintain the freshness by preventing the growth of spoilage bacteria and to reduce visual discoloration, and the method using ice containing ozone gas promotes discoloration of fresh fish. Not practical.
JP 2001-258468 A (Claim 1) JP-A-10-267476 (Claim 2)

  Accordingly, an object of the present invention is to maintain hydrogen gas-containing ice that can maintain a reducing atmosphere for a long time even in a container that is not completely sealed, and can prevent the decay of fresh fish and the progression of meth (discoloration). It is providing the manufacturing method and the preservation | save method of fresh food.

  In such a situation, the present inventor has conducted intensive studies, and as a result, if hydrogen gas-containing ice containing hydrogen gas or a mixed gas of hydrogen gas and an inert gas is used, the present inventor is long even in a container that is not completely sealed. The inventors have found that the reducing atmosphere can be maintained over time, the fresh fish can be prevented from being spoiled, and the progress of metrification (discoloration) can be suppressed, thereby completing the present invention.

  That is, the present invention provides hydrogen gas-containing ice comprising hydrogen gas or a mixed gas of hydrogen gas and inert gas.

  Moreover, this invention provides the manufacturing method of the hydrogen gas containing ice which melts hydrogen gas or the mixed gas of hydrogen gas and an inert gas in raw material water, and makes ice.

  The present invention also provides a method for preserving fresh food in a container, and a method for preserving fresh food that includes fresh food and hydrogen gas-containing ice in the container.

  When the hydrogen gas-containing ice of the present invention is packaged with fresh food in a container, the reducing atmosphere is maintained for a long time in a container that is not completely sealed, and the fresh fish is prevented from being spoiled. Can be suppressed.

  The hydrogen gas-containing ice of the present invention contains hydrogen gas or a mixed gas of hydrogen gas and an inert gas. For example, hydrogen gas or hydrogen gas and hydrogen gas are mixed with raw water at a pressure of atmospheric pressure or higher. It is obtained by dissolving a mixed gas of active gas and making ice. In addition, it is preferable that the raw water is deoxygenated in advance from the standpoint that inhibition of hydrogen gas reducibility can be prevented, and the production of fresh fish due to dissolved oxygen is further suppressed.

  Although it does not restrict | limit especially as raw material water, For example, seawater, a tap water, a pure water etc. are mentioned, Among these, a tap water is preferable at the point which is convenient.

  The method for deoxygenating raw material water is not particularly limited, and known degassing methods including deoxygenation treatment can be used. For example, membrane desorption using a hollow fiber module in which a large number of hollow fiber structure permeable membranes are arranged in parallel. A degassing method using a vacuum degassing tower that drops the raw water from the top of the tower with a high vacuum inside the hollow tower, a method of boiling the raw water and driving out dissolved oxygen to the atmosphere, and a raw water other than oxygen For example, nitrogen gas is blown to remove dissolved oxygen. The concentration of dissolved oxygen in the deoxygenated water is a concentration of 3.0 mg / liter or less, preferably 1.0 mg / liter or less, particularly preferably 0.3 mg / liter or less at 25 ° C. and 1 atm. Oxygen gas is a substance that promotes methotreation of fresh fish, and is also a substance that inhibits the reducibility of hydrogen gas. Accordingly, the deoxygenation treatment can prevent the fresh fish from being met and can inhibit the inhibition of hydrogen gas reducibility.

  A method for dissolving hydrogen gas or a mixed gas of hydrogen gas and inert gas (hereinafter also simply referred to as “hydrogen gas etc.”) in raw water or deoxygenated water is not particularly limited, and for example, in a tank A method of directly expelling hydrogen gas, etc. into the water to be treated, a method of providing an ejector in the water pipe of the water to be treated, and a method of sucking and dissolving the hydrogen gas, etc. And a method using a hollow fiber module in which a large number of permeable membranes having a hollow fiber structure are arranged in parallel. As the hydrogen gas, water electrolysis hydrogen gas, hydrogen gas filled in a cylinder, or the like is used. Examples of the inert gas include nitrogen gas, carbon dioxide gas, argon gas, helium gas, and among these, nitrogen gas and carbon dioxide gas, which are industrially easily available, are preferable. The nitrogen gas may be a product obtained by separating and generating nitrogen gas filled in a cylinder or nitrogen in the atmosphere. Further, in the case of a mixed gas of hydrogen gas and inert gas, it may be dissolved individually in the water to be treated. When the raw material water and hydrogen gas are dissolved in contact, the removal of dissolved oxygen and the dissolution of the inert gas and hydrogen gas may be performed simultaneously.

  In water in which hydrogen gas or the like is dissolved, the dissolved hydrogen concentration is 0.02 mg / liter or more, preferably 0.05 mg / liter or more. The volume ratio of dissolved hydrogen gas to the total dissolved gas of hydrogen gas and inert gas in the water is preferably 15% by volume or less, particularly preferably 10% by volume or less. If the dissolved hydrogen concentration is within this range, the inside of the container can be made a reducing atmosphere in the process of melting the hydrogen gas-containing ice obtained by ice-making this reducing water.

  The method of making the hydrogen gas-dissolved water is not particularly limited, and the hydrogen gas-dissolved water can be produced using a known ice making machine in which a refrigerant circulates through a compressor, a condenser, and an evaporator. Moreover, it is preferable that the ice-making speed is quick cooling and freezing within 5 minutes, preferably within 3 minutes, from the viewpoint that the hydrogen gas contained in the ice can be increased. Moreover, as a form of ice, the thing of a lump shape or a block shape is similarly preferable at the point which can increase the hydrogen gas contained in ice. Examples of a method for producing a block or block of hydrogen gas-containing ice include, for example, the first step of producing a hydrogen gas-containing ice piece in the form of small fragments or foil pieces, and the hydrogen gas-containing ice piece obtained in the first step. And an ice-making method having a second step of cooling and freezing a mixture of water and hydrogen-dissolved water to obtain block-shaped or block-shaped hydrogen gas-containing ice. In this case, at least the first step is performed by rapid cooling and freezing. The block or block-shaped hydrogen gas-containing ice obtained by such two-stage ice making is not easily melted, so that hydrogen gas in the ice is gradually generated. For this reason, the freshness maintenance effect by hydrogen gas can be maintained over a long period of time. Also effective is a method in which hydrogen gas or a mixed gas of hydrogen gas and an inert gas is pressurized during ice making. Thereby, high concentration hydrogen gas can remain in raw material water, and the amount of hydrogen gas contained in ice can be increased.

  In the hydrogen gas-containing ice of the present invention, the concentration of hydrogen contained is approximately 0.02 to 0.25 mg / liter at 25 ° C. and 1 atm. The dissolved hydrogen concentration of the hydrogen gas-containing ice can be confirmed by a known method in which the hydrogen gas-containing ice is put in a sealed container and the dissolved water after a predetermined time has passed is measured with a dissolved hydrogen meter.

  The method for preserving fresh food of the present invention is a method for preserving fresh food in a container, in which the fresh food and hydrogen gas-containing ice are bundled. The fresh food is not particularly limited, and examples thereof include meat such as pigs, cows, birds, and horses, and fish such as vegetables and tuna. These fresh meat fish are required to maintain their freshness, and are handled, for example, by a distribution channel displayed in a supermarket after harvesting. In addition, the size of the fresh meat fresh fish is not limited. For example, tuna meat, meat chunks divided into 4 pieces, block meats cut into 3-4 kg, and store display meats for housewives, etc. Examples include fillets cut up to 100 grams. Among the above-mentioned fresh foods, particularly fresh fish can remarkably suppress the progress of anti-corruption and methacrylation (discoloration), and the effects of the present invention are remarkably exhibited.

  In this invention, it does not restrict | limit especially as a container, The container which uses plastics, vinyls, and metals as a raw material can be used. Further, the container may be either a sealed container or an unsealed container. Even in a container that is not completely sealed, for example, a toro box used for transporting fresh fish, it is possible to remarkably suppress the progress of anti-corruption and methottization (discoloration) of fresh fish packed in the toro box.

  In the present invention, fresh food and hydrogen gas-containing ice are packaged in a container. The packaged state of the fresh food and the hydrogen gas-containing ice in the container is not particularly limited, and is used in the same manner as the conventional method of using ice. Therefore, when transporting fresh fish in a toro box, seawater or the like may be mixed in addition to ice containing hydrogen gas. In a state where the fresh food is stored in the container, the standard oxidation-reduction potential of the moisture adhering to the surface of the fresh food is −10 to −1000 mV, preferably −100 to −600 mV, using the standard hydrogen electrode as a reference electrode. The standard redox potential can be measured by a known method. The moisture adhering to the surface of fresh food is a mixture of adhering moisture from the outside and, for example, meat and fish juice coming out from the inside to the surface. If the standard oxidation-reduction potential of the moisture adhering to the surface of fresh food is within the above range, fresh food will be exposed to a reducing atmosphere. For example, pigmented proteins called myoglobin and hemoglobin in fresh fish will be oxidized. And can maintain freshness over a long period of time.

In the method for preserving fresh food of the present invention, hydrogen gas or a mixed gas of hydrogen gas and inert gas contained in ice is gradually released into the container as the ice melts, It is diffused into the gas phase, and the inside of the container can be made a reducing atmosphere. Further, the release of hydrogen gas or a mixed gas of hydrogen gas and inert gas from ice is continuously performed in the process of melting ice, and the container is maintained in a reducing atmosphere at least until the ice is completely melted. be able to. As a result, it is possible to prevent methyosis (discoloration) of fresh fish at the same time while preventing bacterial growth due to low-temperature storage.
EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

(Production of ice containing hydrogen gas)
A mixed gas with a volume ratio of 96% nitrogen gas and 4% hydrogen gas was aerated at a rate of 10 liters / minute for 5 minutes into 1000 ml of tap water to drive out the dissolved oxygen concentration. In addition to 0.5 mg / liter or less, hydrogen gas-dissolved water was obtained. The dissolved hydrogen concentration in the obtained reducing water was 0.07 mg / liter. Next, the obtained reducing water was immediately put into a commercially available batch type ice making machine having an ice making capacity of 16 kg / h and subjected to quick cooling and freezing for 3 minutes to obtain massive hydrogen gas-containing ice. The hydrogen concentration contained in the hydrogen gas-containing ice was 0.06 mg / liter.

(Fish color discoloration experiment A)
Discoloration experiment using tuna red meat was conducted. That is, 1 kg of block hydrogen gas-containing ice and 200 g of tuna red meat obtained by the above method are placed in a styrene foam foam box with an internal volume of 5 liters, covered with a lid, and stored at an external temperature of 20 ° C. for 10 hours. did. The toro box is not completely sealed even if it is covered. After storage for 10 hours, the lid was opened and the red tuna meat was visually observed. In addition, the presence of ice pieces was still observed in the toro box after 10 hours. Table 1 shows the results of visual observation of red tuna.

Comparative Example 1
(Manufacture of ice without hydrogen gas)
Tap water was put into a commercially available batch type ice making machine having an ice making capacity of 16 kg / h, and subjected to normal cooling and freezing for 10 minutes to obtain lump ice.

(Fish color discoloration experiment)
The tuna red meat was visually observed in the same manner as in Example 1 except that the hydrogen gas-free ice obtained by the above method was used instead of the hydrogen gas-containing ice. Further, the redox potential of the ice dissolved water in the Toro box was measured using a redox potentiometer. The results are shown in Table 2.

Comparative Example 2
(Fish color discoloration experiment B)
Discoloration experiment using tuna red meat was conducted. That is, 1 kg of massive hydrogen gas-free ice and 200 g of tuna red meat obtained in Comparative Example 1 are placed in a styrene foam foam box having an internal volume of 5 liters, a gas inlet is provided on one side, and the other side is provided. A lid with a gas outlet was attached. Next, a mixed gas of 96% nitrogen gas and 4% hydrogen gas in a volume ratio of 10 liters / minute flows into the trolley box from the gas inlet for 1 minute, flows out from the gas outlet, Air was replaced with a mixed gas. After replacement for 1 minute, the gas inlet and the gas outlet were sealed. As in the first embodiment, the toro box is not completely sealed even if it is covered. Furthermore, from this state, it was stored for 10 hours at an external temperature of 20 ° C. After storage for 10 hours, the lid was opened and the tuna was visually observed. The results are shown in Table 1.

  The same procedure as in Example 1 was performed except that a mixed gas of 90% nitrogen gas and 10% hydrogen gas was used instead of the mixed gas of 96% nitrogen gas and 4% hydrogen gas. The oxidation-reduction potential of the ice-dissolved water in the Toro box after storage for 10 hours was measured using an oxidation-reduction potentiometer. The results are shown in Table 2.

Comparative Example 3
The same procedure as in Comparative Example 2 was performed except that a mixed gas having a volume ratio of 90% nitrogen gas and 10% hydrogen gas was used instead of the mixed gas having a volume ratio of 96% nitrogen gas and 4% hydrogen gas. The oxidation-reduction potential of the ice-dissolved water in the Toro box after storage for 10 hours was measured using an oxidation-reduction potentiometer. The results are shown in Table 2.

本発明による生鮮食品の保存方法によれば、実施例１が示すように鮮魚の変色防止に効果があり、また、実施例２に示すように、容器内が還元性雰囲気に保たれていることによるものであることが判る。

According to the method for preserving fresh food according to the present invention, as shown in Example 1, it is effective in preventing discoloration of fresh fish, and as shown in Example 2, the inside of the container is maintained in a reducing atmosphere. It can be seen that

Claims (6)

  A hydrogen gas-containing ice comprising hydrogen gas or a mixed gas of hydrogen gas and inert gas.   A method for producing hydrogen gas-containing ice, characterized in that hydrogen gas or a mixed gas of hydrogen gas and an inert gas is dissolved in raw water to produce ice.   3. The method for producing ice containing hydrogen gas according to claim 2, wherein the raw water is deoxygenated in advance.   A method for preserving fresh food in a container, wherein the fresh food and hydrogen gas-containing ice are packaged in the container.   The method for preserving fresh food according to claim 4, wherein the hydrogen gas-containing ice contains hydrogen gas or a mixed gas of hydrogen gas and inert gas. The method for preserving fresh food according to claim 4 or 5, wherein the container is a trolley box made of expanded polystyrene resin, and the fresh food is fresh fish.