JPH0630744A - Material for keeping freshness of perishable food - Google Patents

Abstract

PURPOSE:To provide a freshness-keeping material capable of preserving a perishable food over a long period by adjusting perishable food, preventing the oxidization of the food to deteriorate the food quality such as freshness, taste and flavor and suppressing the generation of ethylene gas from fruits. CONSTITUTION:The substrate of the freshness-keeping material is a porous material made of aluminum 3 or aluminum alloy and has a number of cavities on the outer surface or in the material and at least a part of the cavities are connected with each other. Whiskers 4 composed mainly of aluminum oxide are formed on at least a part of the interconnecting holes 2 formed by the cavities and fine water particles 5 can be held with the whiskers. The supercooling near the outlet of chilled air can be suppressed and the temperature change caused by the opening of a refrigerator door can remarkably be reduced by lining the inner wall surface of a refrigerator with the freshness-keeping material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a freshness preservation material for fresh foods, and more particularly, it can effectively retain the quality or freshness of fresh foods for a long period of time, and when storing fresh foods at a low temperature in a refrigerator or the like. When used for, alleviates overcooling in the vicinity of the cool air outlet in the refrigerator, quickly absorbs temperature changes when opening and closing the refrigerator, and evens out the flow of cold air in the refrigerator.
Fresh food that should be refrigerated can be cooled without overcooling, and it also activates water, etc., and this activation causes the fresh food and the water contained therein to act to maintain the quality and freshness of the fresh food. It relates to freshness preservation materials that can be used.

In the following, it is general foods that the freshness preservation material according to the present invention can be applied to achieve the effect, but particularly remarkable effects can be achieved, for example, in addition to vegetables, fruits and seafood. , Coffee, luxury items like green tea, cut flowers,
These are fresh foods including plants such as seeds.

[0003]

2. Description of the Related Art Various holding methods, holding tools, and holding devices have been proposed and implemented for a long time in order to maintain the freshness of seafood, meat, vegetables, agricultural products and other fresh foods. Also, research and development on this point have been made steadily even now, and at present, a technique for preserving fresh foods without canning or heat sterilization has been proposed from various fields, and this technique enables us to Life has been diversified and many benefits have been brought.

[0004] This preservation technique can be broadly classified into whether to suppress the cell activation function of fresh food or to block or prevent the progress of ripening and spoilage of fresh food.

Further, the former is divided into cold preservation and frozen preservation.

[0006] That is, cold storage is a method in which fresh food is stored at room temperature or below, that is, by cooling the water contained in the food without freezing, and in this method, so-called cooling and chilling are performed. Is included. This preservation technology is a method of preserving the quality and freshness of fresh foods without heat sterilization, drying, salting, sugaring, etc., which suppresses the activity and reproduction of bacteria involved in decay and aging. , Keeps quality and freshness. This method has been greatly improved in recent years,
It has the feature that it can be stored as it is without impairing the quality and freshness of fresh food.

Freezing preservation is a method in which fresh foods are cooled to a temperature below the freezing temperature of water and the central temperature of the fresh foods is below -18 ° C and stored in ice for storage. Since this method has extremely high storability, it is used on ships and for long-term storage, but since the food tissue is easily destroyed by freezing, there are problems in terms of texture and quality after thawing.

On the other hand, the latter produces ethylene when fresh vegetables, fruits, etc., mature, and pays attention to the fact that ethylene promotes the respiration of vegetables, fruits, etc. to promote maturation. It is a method of shutting off the involvement or adjusting the storage atmosphere with, for example, carbon dioxide. That is, the ethylene treatment blocks the progress of ripening of vegetables and fruits, or removes ethylene from ripe fruits and vegetables to block the further ripening of fruits and vegetables.

This technique can achieve a certain degree of effect on the prevention of spoilage of fresh foods, but it does not maintain the quality and freshness, and cannot keep fresh foods in a raw state.

From this point of view, attention has been paid to the fact that the water contained in fresh foods is closely related to the quality and freshness in recent years, and the quality and freshness are adjusted by adjusting the nature and structure of the water contained in the fresh foods. A technique for retaining the has been proposed. This technique has been proposed in the form of, for example, using water activated by treatment with an electrostatic field or a magnetic field for preservation of fresh food, growth of plants and production of food.
In particular, it has been empirically reported that the use of this activated water has a predetermined effect on the growth of plants, the freshness of fresh foods and the adjustment of the environmental atmosphere.

In this technique, the empirical results precede and the theoretical elucidation associated therewith is slightly behind. However, the structurally modified active water can prevent red rust in the water pipe, give good biological activity to plants and animals, and by the way, improve the egg laying rate of poultry and activate the physical strength of severely farmed cattle. Achievement of inaccessibility of plants, promotion of plant growth, etc. have already been demonstrated.

More specifically, the fresh food, and more generally the water surrounding the cells, consists of three layers, free water, bound water, and antifreeze water, and the amount of these waters is about 80-8.
It has reached about 5%. In particular, as in fresh foods and plants, the expression "freshness" means that the water contained is directly and deeply related to the quality and freshness of foods. Therefore, in fresh foods, the structure and properties of free water existing at the outermost part are adjusted and activated,
It is fully advocated that the freshness of fresh food, that is, freshness, can be maintained as long as possible by replacing the outermost free water with activated water whose structure and properties are adjusted. Therefore, from these viewpoints, it is necessary to utilize the already proven activated water for keeping the freshness of fresh food.

In other words, the conventional freshness-keeping technology for fresh foods is, as described above, for lowering the temperature of fresh foods, refrigerating, encapsulating carbon dioxide gas, and removing ethylene. At the same time, it is desirable to use activated water having a controlled structure or property in order to maintain the freshness of fresh food.

[0014] However, it is extremely effective to adjust the structure and properties of water and activate it, or to further advance and effectively use water that has been activated to maintain the quality and freshness of fresh food. In spite of this, since the adjustment means and the equipment are hardly developed at present,
At present, freshness preservation cannot be improved beyond the conventional technical field.

[0015]

The present invention has been made in view of the background described above, and specifically, it is an antioxidant that inhibits the quality of fresh foods, such as freshness, taste and aroma. In addition to suppressing ethylene gas released from fruits, we propose a freshness preservation material that can preserve fresh food for a long time by adjusting the structure and properties of water contained in fresh food.

[0016]

That is, the freshness preserving material according to the present invention has a large number of voids formed on the outer surface or inside thereof, and a part or all of each void communicates with each other. In, a whisker containing aluminum oxide as a main component is generated in at least a part of the communication hole formed by these voids, and fine water is carried through the whisker.

The base material of aluminum or its alloy is made of a powdered or fibrous sintered material of aluminum or its alloy material, or a base material of aluminum or its alloy. Is a fibrous aggregate obtained by collecting fibrous aluminum or its alloy material, or a foam obtained by foaming aluminum or its alloy material.

Further, the fine water carried through the whiskers constitutes a base material of aluminum or its alloy from a powdered or fibrous sintered body of aluminum or its alloy material.

More specifically, the freshness preservation material according to the present invention is a porous material of aluminum or its alloy.

First, a porous material of aluminum or its alloy is manufactured by using a powder or fiber material of aluminum or its alloy as a raw material by a sintering method, a foaming method or the like. This manufacturing method is described in Japanese Patent Publication No. 60-47322. Already known as mentioned.

A whisker containing aluminum oxide as a main component is formed on at least a part of the innumerable communicating holes of the porous material. The formation of whiskers can be carried out by so-called boehmite treatment, but in this case it is necessary to use pure water. That is, pure water is boiled or turned into steam, and these are made to act on the porous material to form a whisker consisting of innumerable ultrafine aluminum oxide hydrates on the communication holes inside and on the surface of the porous body. To generate. This whisker is a very thin and whisker-shaped extension, and a gap having an extremely small diameter is formed between adjacent whiskers. Therefore, fine water, that is, fine particles of water, can be carried between the whiskers.

Further, the water carried through the whiskers is preferably water whose structure and properties are adjusted so that the evaporation rate is slower than that of pure water. This water includes so-called activated water, which has a different structure and properties compared to ordinary tap water or distilled water.

[0023] That is, water is generally represented by the molecular formula of H ₂ O, but the water molecules H ₂ O seems to exist in isolation, molecular bonded each water molecule in recent years It is considered to form a group, and this is also called crystallisation of water molecules. Since the crystal structure of ordinary water that is generally obtained, such as ordinary tap water and distilled water, is a combination of water molecules in a rod shape or a linear shape, when heated, single water molecules are separated and the viscous resistance is small. It is said to be.

On the other hand, when the structure and properties are adjusted, the crystal structure of water becomes a ring structure in which rod-shaped water molecules are cyclized and bonded, or a three-dimensional structure in which this ring structure is combined. The properties and the like are greatly different from water, and the viscous resistance is less likely to decrease during heating. For example, the evaporation rate is slower than that of normal water. By the way, the snowmelt water and natural spring water of Mt. Fuyu have a slight structural difference from normal water, and therefore have different tastes and flavors.

Such adjustment of the structure and properties can be achieved by any method, but can be achieved by the following treatment. (1) magnetic field treatment, (2) electric field treatment, (3) microwave treatment, (4) ultrasonic treatment, (5) ceramic treatment, (6)
Ozone treatment, (7) Pi treatment, (8) Nuclear magnetic resonance treatment, (9) Far infrared treatment, (10) Microwave oven treatment,
(11) Natural stone treatment,

Now, the structure and operation of these means will be described more specifically with reference to the drawings.
It is as follows.

FIG. 1 is an explanatory view showing an enlarged part of the surface of the freshness preservation material according to one embodiment of the present invention,
2 is an enlarged view showing a whisker portion formed on the inner wall surface of a communication hole formed between particles of the aluminum or its alloy, and FIG. 3 is a view showing pores formed by the whisker or the like. It is a graph which shows the relationship between a radius and the vapor pressure of the water carried.

First, in FIG. 1, reference numeral 1 indicates a base material of aluminum or its alloy in the freshness preservation material according to the present invention. The base material 1 is a porous material of aluminum or its alloy. This base material 1 has a communication hole 2 which is three-dimensionally communicated, and the ratio of this communication hole 2 is 20 to 70 in terms of volume ratio.
% Is preferable. To manufacture, powder of aluminum or its alloy is used as an aggregate raw material, metal powder for binder having a lower melting point than powder of this aluminum or its alloy is mixed, and this mixed powder is sprayed without pressure, Firing is performed in an oxidizing atmosphere at a temperature between the melting point of the binder metal and the melting point of the aggregate and sand of aluminum or its alloy powder. At this time, it is possible to adjust the porosity of the proportion of the communication holes 2 by selecting the shape and particle size of the powder particles of aluminum or its alloy as the aggregate raw material as desired.

In addition to sintering, the base material 1 can also be manufactured by compression molding fibrous aluminum or foaming molten aluminum.

As described above, when the base material 1 is made of a porous material of aluminum or its alloy, and the communication hole 2 that bends infinitely is formed inside, it is lightweight and has thermal conductivity due to its material characteristics. Excellent and structurally, it has a complex surface shape and has a large number of communication holes, and has a large surface area, so it has good heat dissipation properties. By suppressing supercooling, the temperature change during opening and closing can be greatly mitigated.

Further, as shown in FIG. 3, the outer surface of the base material 1 is heated by boiling the base material 1 made of a porous material of aluminum or its alloy in water and then heating it in the atmosphere at 100 ° C. or higher. Besides, whiskers-4 are generated on the inner wall surface of the communication hole 2 formed between the aluminum particles 3 forming the aggregate. Each whisker-4 is mainly composed of a hydrate of aluminum oxide, but if an organic amine, sulfuric acid or the like is added during the boiling treatment as a manufacturing means, these can be blended in the hydrate. Whiskers-4 formed by this treatment are whiskers and elongated,
Its diameter is about 0.01 μm, and the distance between adjacent whiskers-4 is about 0.03 μm or less.

Next, in the base material 1 having the above structure, the water 5 is supported in the form of fine particles through the whiskers 4 formed inside the surface as well as inside. This support is usually sprayed.
Alternatively, it is impregnated with water by dipping and then at 200 ° C.
Water 5 can be supported by drying below.

That is, when drying at a high temperature of 200 ° C. or higher, the drying is completed and the water 5 cannot be left in the whiskers-4 at all. For this reason, preferably 10 after impregnation.
It is heated at a temperature of 0 ° C. or less and fine water is carried between the whiskers 4 and the like, and such water is carried on the entire wall surface of the communication hole 2 which three-dimensionally communicates inside.

Water 5, such as activated water, can be carried through the whiskers 4 regardless of the surrounding atmosphere because the gaps between the whiskers 4 are extremely fine.

That is, the vapor pressure drop in the pores of a liquid such as water is governed by the Kelrin's equation, and this is obtained for water as shown in FIG. Note that FIG.
(A) shows 100 ° C, and (b) shows 20 ° C. It can be seen from FIG. 3 that water usually boils at 100 ° C. under 1 atm, but when the radius of the pores is 0.01 μm, the water even condenses rather than boils. Therefore, if the gap between the whiskers-4 is extremely small, such as 0.01 [mu] m or less, the water carried on the whiskers-4 can be carried stably without evaporation even when heated after the water impregnation.

Next, since there are innumerable communication holes structurally and each communication hole is provided with fine whiskers, the flow becomes uniform while the cold air in the refrigerator passes, and the fresh food is localized. Overcooling can be prevented.

Further, with aluminum or its alloy constituting the base material itself, it is extremely easy to store and cool heat,
Since the surface area is large due to the above-mentioned configuration, at the outlet of the cool air of the refrigerator, it serves to mitigate the cool air, and it is possible to prevent overcooling near the outlet.

Therefore, the relationship between the quality of fresh food and the preservation of freshness of the freshness preservation material constructed as described above is as follows.

First, with the above-mentioned structure, ripening of vegetables, fruits and the like can be blocked. That is, when vegetables and the like are aged by interposing the freshness preserving material having the above structure, the effect of interrupting the aging itself can be achieved with almost no generation of ethylene gas, which is only generated during the aging, as compared with the case where the vegetables are not aged. Although the reason for this is unknown in detail, the water carried through Whisker-4 is
The substrate 1 is made of aluminum or its alloy and emits far infrared rays. Therefore, a far-infrared field is formed where water is supported, and this field causes structural changes in the water, and the structurally changed water causes the water content in the atmosphere such as air to change. It is thought that the active water atmosphere is formed around vegetables and so on. This tendency is further enhanced when the previously activated water is carried.

When an atmosphere containing active water is formed around fresh food, water contained in fresh food, for example, free water on the surface (this free water is structurally usually Unlike water, it has a structure similar to active water)
After aging, the fresh food surface can always maintain its freshness because there is always enough free water on the surface. That is, the activated water and the free water have a slower evaporation rate than the normal water as described above, and the freshness is always maintained for a long period of time.

Further, the formation of such an atmosphere suppresses the surface oxidation of the fresh food, and the scattering of the scent can be suppressed in the case of placing emphasis on the scent such as coffee and the like.

[0042]

【Example】

Example 1. While preparing an aluminum porous sintered material obtained by sintering aluminum powder particles,
Was boiled for 1 hour in water of 00 ° C., dried for 1.5 hours at 0.99 ° C., whiskers - was generated, further, so that the evaporation rate is slower than normal water, 10 ^-12 activated by a magnetic field treatment
Spray the moles with a spray to impregnate, then at 8O 0 C for 8 hours.
Allowed to dry for hours. Bull-Mountain roasted both of these materials was placed in a container and held for 1 week to check the freshness. The results are shown in Table 1. The evaluation was based on the following criteria. Evaluation 1 ... The taste is not changed and is good. 2 ... The taste is slightly reduced. 3: The taste is slightly reduced and the scent becomes lighter. 4 ... In addition to a slight loss of taste, the scent becomes very light. 5: Bad

Example 2. The procedure of Example 1 was repeated, except that the vacuum pack of green tea was opened instead of the coffee of Example 1 and transferred to a can container. The results are shown in Table 2. The evaluation was also performed under the same conditions as in Example 1.

[0044]

[Table 1]

[0045]

[Table 2]

That is, since coffee, black tea, green tea, etc. are originally personal favorite products, they are foods that require their aroma, taste, and other delicate characteristics.
The quality and grade of the coffee itself change depending on the roasting conditions of the coffee beans. Of course, it also has characteristics depending on the coffee production area, and a typical example is Jamaica's Bull Mountain, which has many enthusiasts in Japan. Bull-Mountain is where its pure scent is prized.

When drinking coffee, roasted coffee beans are ground and used as a powder immediately before drinking to obtain a coffee with a good taste and aroma. However, the coffee beans once made into a coffee powder may be left as it is, or may be changed in a state of being sealed in a general metal container, and its taste and aroma may be slightly changed.

In addition, crude sugar (the tannin exists as a glycoside and the sugar consists of sucrose and glucose) which are the main components of roasted coffee, crude protein, fat, caffeine, crude fiber, It is not clear which comprehensive components such as ash affect taste and scent and which alteration should be suppressed, but it is generally necessary to prevent oxidation and fragrance dissipation.

However, when the holding material according to the present invention is used, freshness can be maintained, and the aroma, sourness and bitterness contained in coffee and the like are easily oxidized by oxygen in the air. Nevertheless, subtle oxidation could be prevented.

Example 3. Using the freshness preservation material according to the present invention shown in Example 1 as a lining in a refrigerator, 20 apples were put therein. On the other hand, 20 apples were put in the refrigerator as it was in the conventional example.

First, FIG. 4 shows the results of a comparative investigation of the time course of ethylene concentration. At this time, the inside of the refrigerator is made of only the apple, the refrigerator temperature is kept within the range of 8 ± 0.5 ° C with the refrigerator door closed, and the inside gas is fed through the gas introduction pipe connected to the inside of the refrigerator. 10 ml each was sampled and the ethylene concentration was measured by gas chromatography. As a result, in the commercial refrigerator, the ethylene concentration rises with the passage of time, whereas in the refrigerator according to the present invention,
Immediately after entering the warehouse, the concentration was close to that of the commercial refrigerator, but it decreased with time, and after about 5 hours, it decreased to an equilibrium value, after which it was found that a low ethylene concentration could be maintained. Adsorption of ethylene by alumina whiskers Was confirmed. Apple is known as a plant that emits a large amount of ethylene.

FIG. 5 is a comparative study with the case of a commercial refrigerator in which the transition of the temperature inside the refrigerator when the door of the refrigerator kept at 8.5 ° C. is fully opened for 10 seconds is automatically recorded by the thermocouple set in the refrigerator. In the commercial refrigerator, the internal temperature rises up to 17 ° C, and it takes about 110 seconds after the door is closed to recover the preset temperature of 8.5 ° C. , In the present invention,
It was found that the internal temperature rises only to 14 ° C and that the temperature is restored to the set temperature in about 40 seconds after the door is closed, confirming the high cold storage capacity.

Table 3 shows the results of observing the state of spinach stored in a refrigerator kept at 7 ° C for 5 weeks and comparing it with the case of a commercial refrigerator. In addition, yellowing of the leaf tips is observed and the leaves almost rot after 3 weeks, whereas in the present invention, yellowing of the leaf tips occurs only after 3 weeks, and long-term storage of almost 3 weeks is required. It was confirmed that it was possible.

[0054]

[Table 3]

Regarding this experiment, considering that the doors are not opened except for weekly observation of the inside of the chamber, and that spinach is a type of plant that hardly releases ethylene, the results of this experiment are shown. It is difficult to explain it only by the cold-retaining effect and the ethylene release-suppressing effect, and it must be considered that the active water-containing alumina whiskers have some freshness-retaining effect which has not been clarified yet.

[0056]

As described in detail below, according to the present invention, a large number of voids are formed on the outer surface or inside, and a part or the whole of each void is communicated with each other. It is a freshness preservation material for fresh foods in which whiskers containing aluminum oxide as a main component are formed in at least a part of the communication holes formed by the above, and fine water is carried through the whiskers.

Therefore, by interposing the freshness preservation material according to the present invention, the quality or freshness of the fresh food can be effectively maintained for a long period of time, and when it is used when the fresh food is stored at a low temperature in, for example, a refrigerator, the refrigerator. Alleviate the supercooling around the cold air outlet inside, quickly absorb the temperature change when opening and closing the refrigerator, even the flow of cold air in the refrigerator, you can cool the fresh food to be refrigerated without overcooling, Further, while activating water and the like, this activation can act on the fresh food and the water contained therein to maintain the quality and freshness of the fresh food.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an enlarged part of a surface of a freshness preservation material according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a whisker portion formed on an inner wall surface of a communication hole formed between particles of the aluminum or the alloy thereof.

FIG. 3 is a graph showing the relationship between the radius of pores formed by whiskers and the like and the vapor pressure of water carried.

FIG. 4 is a graph showing the relationship between the time of storage in the refrigerator and the ethylene concentration during aging for the present invention and the conventional example.

FIG. 5 is a graph showing a relationship between a refrigerator door opening time and a refrigerator temperature for the present invention and a conventional example.

[Explanation of symbols]

 1 Base Material 2 Communication Holes 3 Aluminum Particles 4 Whiskers 5 Water

Claims (4)

[Claims] 1. A base material made of aluminum or an alloy thereof, in which a large number of voids are formed on the outer surface or inside, and some or all of the voids communicate with each other, and at least a part of the communication holes formed by these voids. A freshness preservation material for fresh foods, which comprises producing whiskers containing aluminum oxide as a main component and carrying fine water through the whiskers. 2. The freshness preserving material for fresh foods according to claim 1, wherein the base material of aluminum or its alloy is composed of a sintered body of powdery or fibrous aluminum or its alloy material. 3. The fresh food according to claim 1, wherein the base material of aluminum or its alloy is a fibrous aggregate in which fibrous aluminum or its alloy material is aggregated or a foam in which aluminum or its alloy material is foamed. Freshness preservation material. 4. The freshness preservation material for fresh food according to claim 1, 2 or 3, wherein the fine water is water having a slower evaporation rate than ordinary distilled water.