JPS5941391B2 - How to freeze food - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frozen preservation method for preserving foods, particularly seafood, meat, and other fresh foods, or sushi, mochi, and other cooked foods for a long period of time.

The present applicant has already proposed in Japanese Patent Application No. 55-146084 a new frozen preservation method that goes beyond the conventional concept of frozen foods.

The present invention was made based on new experimental results and theories based on further research based on the invention of this application. By introducing this theory, a completely new cryopreservation method was completed.

In other words, it is generally considered that food should be frozen as quickly as possible and stored at a low temperature. However, conventional freezing preservation technology treats fresh food as a single, inanimate object, and It has been created through experimental methods viewed from a physical perspective.

However, with such conventional techniques, it is impossible to obtain an essential freezing preservation method that prevents food from deteriorating in quality.

In general, a living organism has the ability to reproduce the same thing as itself, and when that function is lost, it is called death. If an animal loses its defenses against foreign enemies, etc., it can be judged as death at the individual level, but it cannot necessarily be judged as death at the cellular level.

A cell consists of cytoplasm and is surrounded by four cell membranes.

The cell nucleus contains chromosomes and synthesizes messenger RNA, which conveys genetic information.

Of course, they also have a self-replication system for the DNA that makes up their genes.

The cytoplasm dissolves various soluble substances (metabolites and enzymes) and contains many microstructures (for example, the cytoplasm contains respiratory enzymes and the midochondrum, which is the site of ATP production.
1a and ribosomes, which are the site of protein synthesis) When viewed at the cellular level, the three-dimensional structure of proteins,
Changes in intracellular ion concentration and lipids greatly affect cell activity.

The mechanism of cell production is that substances are broken down into 20 types of amino acids by the action of enzymes, and then produced in a factory-like place called a ribosome in a midcond (1) a, according to the genetic information in the DNA within the cell. energy AT
Using P as an RNA worker, a three-dimensional structure composed of consecutive amino acids is again constructed.

The bonds between these three-dimensional structures are Bev-bond bonds, and the assembled substance is nothing but protein.

Experiments have shown that when a three-dimensional structure like this object is pushed away, the enzyme's function disappears, and when it is returned to its original structure, it resumes its enzyme function.

Kada production activities are carried out at appropriate temperatures according to each animal and plant.
This is done by obtaining moisture, gas composition, pressure, light, etc., and changes in moisture, temperature, and gas composition in particular have a very large effect on life activities.

Furthermore, it is important that free water, which freely passes through cell membranes and moves, changes the electrolyte concentration of half-thorium ions and potassium ions, causing a factor that inhibits biological reactions.

Taking these points into consideration, from a molecular biological perspective, is it ideal to keep food to be preserved at a low temperature of -20°C while suppressing enzyme activity and creating an unfrozen state for both free water and bound water? , this is physically impossible.

Therefore, in cryopreservation, which naturally involves the freezing of free water and bound water in foods, free water and bound water in food can be preserved without cutting these ice crystals or peptide bond joints or pushing away the three-dimensional structure of the protein. Ideally, the bound water should be frozen so that it does not move.

If there is no water in the immediate vicinity of the broken three-dimensional structure, it will easily combine with other substances when it is thawed, and this will prevent the enzyme from acting, so ice crystals may be distributed finely and uniformly in the food. is necessary.

Based on such analysis, the present invention has developed a method in which the ice crystals are so fine that they do not break peptide bond joints or are extremely small, and can form ice crystals uniformly in foods while preventing moisture movement. Basically, the freezing capsule forming process involves forming frozen capsules on the outer circumferential surface of the food to be stored frozen and cooling the food to the core temperature of 0°C to 3°C; A supercooling process in which food is cooled to a temperature below 16°C by creating a supercooled state in which the food passes through the crystal formation zone in an unfrozen state; the food is cooled so that the outer temperature and center temperature of the food are in balance. A slow cooling step: and a freezing step in which the food is cooled to form ice crystals in the food.

Each step will be explained below.

■) Freezing capsule formation process Freezing capsules have the purpose of removing the adverse effects of turgor pressure when food is frozen by fixing the outer periphery of the food with a strong capsule. By increasing its abundance, it prevents free water and bound water from freezing when passing through the maximum ice crystal formation zone, or increases the possibility of making frozen ice crystals finer.

This process lowers the core temperature of the food to the maximum ice crystal formation zone (-1
The purpose is to lift the ship just before the temperature (00C~-5℃), that is, around 00C~3℃.

This freezing capsule forming step is preferably carried out at -25°C.
This is achieved by blowing -45°C cold air around the outer periphery of the food for 10 to 40 minutes.

At this time, depending on the food, moisture is appropriately added to the outer periphery.

When the cooling temperature is 125°C or higher, the outer ice crystals are 300 μm thick.
It grows to a size of ~900 μm and destroys cells.

If the temperature is below 45°C, the difference between the peripheral temperature and the center temperature will be too large, and the difference in osmotic pressure will cause movement of free water, which may change the pH.

In this step, the difference between the center temperature and the outer circumferential temperature is minimized, and the center temperature is kept at around 0.8 to 3.degree. C. while preventing moisture from moving from the center to the outer circumference.

By fixing the outer periphery and freezing a portion of the inside using the freezing cabbage, the internal pressure is high, the water is fixed, and a freeze-resistant condition is created.

2) Supercooling step This process creates a supercooling state in which the maximum ice crystal formation zone (-1°C to -5°C) is passed through in a non-freezing state.

In other words, the cooling conditions are determined so that both free water and bound water do not freeze as much as possible.
It is best to blow cold air at a temperature between 10°C and -90°C for 10 to 30 minutes.

At temperatures above -50°C, a supercooled state cannot be created and freezing occurs, and below 90°C, energy is wasted.

This supercooling process cools the water to -70°C to -90°C.
Blowing cold air takes advantage of the phenomenon that when rapidly cooled, it freezes even at -10°C to -78°C, and when shocked, it freezes all at once, and the free water and bound water in the cells are The food passes through the zone of maximum ice crystal formation, and the core temperature of the food becomes -6°C or lower.

3) Slow cooling process When the temperature at the center of the food reaches about 16°C to -10°C, the difference in osmotic pressure causes free water to move from the center of the food to the periphery again, preventing pH changes from occurring. In order to ensure that the amino acids of the protein are in a state of water availability, it is a process to reduce the temperature difference between the center and the periphery, preferably between -25°C and -45°C. Cold air 10-4
Spray for 0 minutes. At temperatures above -25°C, it takes too much time for temperature transfer and temperature equilibrium is delayed.

Further, if it is below -45°C, the temperature difference between the outer circumference and the center increases, which is not favorable.

4) Is it possible to physically freeze the moisture in foods that are difficult to freeze after going through the freezing process and above? In this process, the ice crystals are made into a size on the order of 10 μm without cutting the joints of peptide bonds, and are uniformly distributed in the food.

It is convenient to do this in two stages.

In other words, is the food that was initially supercooled frozen all at once? This is done by blowing cold air at a temperature of 150°C to -90°C for 10 to 30 minutes.

At temperatures above -50°C, the food cannot be brought into the low-temperature range all at once, and a clever freeze that looks like a flower blooming all at once cannot be obtained.

Even if the temperature is below 90°C, the effect of making the ice smaller is that the increased process energy is wasted.

The next step is to slowly freeze unfrozen water, which has strong bonds with lipids, to prevent deterioration.

This is preferably done by blowing cold air between -258C and -45C for 10
This is achieved by spraying for ~40 minutes, and when the core temperature falls below 118°C, the freezing process is completed and the storage state is achieved.

At a cooling temperature of -25°C or higher, freezing takes too long, resulting in a longer refrigeration cycle, lowering the utilization of equipment, and increasing costs. In this case, significant miniaturization effects cannot be obtained and energy is wasted.

When food frozen and preserved through the above steps is thawed by vacuum thawing, natural thawing, etc., the ice crystals on the order of 10 μm that were finely scattered between the three-dimensional structure twigs of the protein melt, and the water usage state with the protein is restored. Return to

As a result, the electrolyte concentration of potassium ions and IJium ions does not change, and from a molecular biological point of view, it is possible to restore the cells to an active state similar to that of living cells.

The effects of the method of the present invention will be explained below with reference to Examples.

<Example 1> In an atmosphere where the temperature inside the cooling box is 15°C (ordinary temperature), 10 (XX 10 CTI'Lx 300
3 g of pork thighs through a sieve length 40 x width 20 cTl x depth 5
A 1c4 spacer was placed and fixed in a crrL stainless steel vessel, and a baling agent solution containing vegetable polysaccharide or gelatin was poured into it and immersed until 1cTL of fog was created above and below the meat pieces, then boiled at 135°. Cold air of C was blown for 25 minutes to form a strong capsule on the surface of the meat piece, and the temperature at the center was set to 3°C.

Next, cold air at -65°C is blown, and in the previous process the water is fixed due to high internal pressure, etc., and the food, which is difficult to freeze, is supercooled and the state is further amplified. and rapidly passing through the zone of maximum ice crystal formation? When I closed it, the center temperature was -6°.
It became C.

Thereafter, the cold air was switched to -35°C and was blown for 25 minutes to slowly cool down while trying to balance the temperature at the outer periphery and the center, and the temperature at the center became 18°C.

Next, the cold air was switched to -65°C and the food was cooled for 15 minutes to bring the temperature of the center of the food to -13°C. Free water crystals with a size on the order of 10 μm were formed all over the food.

Next, the cold air was switched to -35℃ and cooled for 30 minutes to complete the freeze-fixation of bound water and lipids, and the center temperature was -20℃.
It became °C.

Thereafter, it was transferred to a regular freezer at -18°C and stored for 6 months.

Separately, the same amount of three pork thighs was treated with air freezing and air blast freezing at -35°C for 24 hours, then wrapped in a 40 μm thick polyethylene bag and stored in a regular freezer at -18°C for 6 months. And so.

The frozen meat of the present invention and the control group was thawed under vacuum at 3°C, and drips upon thawing, meat color, softness of the meat, and degree of cell destruction in frozen sections were observed under a microscope, and then fried in a frying pan and subjected to a flavor test. The test results shown in Table 1 were obtained.

It will be understood that the frozen preserved meat obtained by the method of the present invention exhibits excellent preservation effects with the same quality as the original meat even after 6 months of freezing.

<Example 2> In a cooling box with a temperature of 15°C (ordinary temperature), three live sweetfish (weight 50 g) and Machi (1.tKp) were killed instantly by medullary blow, and the sweetfish were placed on a stainless steel wire mesh. While rotating the fish body, shake off the loosening agent containing vegetable polysaccharide or gelatin, place the yellowtail on a stainless steel plate, cool it with cold air at 135°C for 30 minutes, and spread it on the surface of the sweetfish to a thickness of 1 crr.
When we formed a strong frozen capsule of L and 0.5 crIL of subcutaneous lipid including the epidermis for yellowtail, the center temperature of both was 2°C.

Afterwards, cool air at -75℃ was blown for 20 minutes to bring the center temperature of the sweetfish to 18℃ and the yellowtail to 16℃.Next, the cold air was blown to 135℃.
Does returning to the temperature and spraying for 30 minutes average out the difference between the outer temperature and the center temperature? After cooling, cool air is blown again at -75°C for 15 minutes, and when the center temperature is -18°C for sweetfish and -14°C for yellowtail, the cold air is returned to -35°C and blown for 30 minutes, and the center temperature is -23°C. ℃, then transferred to a regular freezer at -18℃ and stored for one year.

Separately, kill the same amount of sweetfish and... 3 of each type immediately.
Thickness: 4 after 24 hours of air freezing, airplast freezing and contact freezing at 5℃
It was wrapped in a 0 μm polyethylene bag and stored in a regular freezer at -18° C. for 1 year to serve as a control.

Next, the frozen fish of the present invention and the control group were thawed under vacuum at 3°C, and the drips, flesh color, and softness of the meat upon thawing were measured. When observed under a microscope and further subjected to a flavor test for sweetfish grilled with salt and yellowtail sashimi, the frozen fish according to the present invention was found to be similar to fresh fish after thawing.

Table 2 shows the test results. <Example 3> In a cooling box with a temperature of 15°C (room temperature), three each of 8g halfbeaks and 37g freshly caught live scallops were placed in a box with a width of 15 cTL x length of 30 crrL x depth of 3 c.
Pour a breaking agent solution containing plant polysaccharides, gelatin, or alcohol into a stainless steel vat, completely immerse it in the solution, and blow cold air at -35°C for 20 minutes to freeze capsules with strong crystals. was formed to fix the food from the outside.

At this time, the center temperature was 3°C. After that, when I rapidly cooled it with -65℃ cold air for 10 minutes, the center temperature was still half-baked.
The temperature for the scallops was -10 degrees Celsius.

Furthermore, cold air was returned to -35°C and blown for 15 minutes to reduce the difference in temperature between the outer periphery and the center, and then cooled again with cold air at -65°C for 10 minutes to bring the center temperature to -15°C.

After that, blowing -35℃ cold air for 15 minutes lowers the center temperature to 12
After cooling to 0°C, it was wrapped in a 40 μm thick polyethylene bag and stored in a regular freezer at -18°C for 8 months.

Separately, the same amount of halfbeaks and 3 scallops were treated as a group for 24 hours with air freezing, airplast freezing and contact freezing at 35°C, then wrapped in a polyethylene bag with a thickness of 40 μm and placed in a freezer at 18°C for 8 hours. It was stored for several months and used as a control.

Next, the halfbeaks and scallops of the present invention and the control were collected at 3°C.
Thaw the meat under vacuum, and check the drips, color, and softness of the meat during thawing.
The degree of cell destruction was observed under a microscope using frozen sections of the meat just below the central lateral line of the fish body (halfbeak) and the meat of the center of the scallop (scallop scallop), and the halfbeak was subjected to flavor tests as sashimi and the scallop was fried in a frying pan. Test results of No. 3 were obtained, and the frozen products according to the present invention maintained such high quality that they were indistinguishable from fresh products even after thawing.

<Example 4> Tuna Nigiri Zushiku 40g) and seaweed Sweet Kizushiku 3 in an atmosphere with a cooling box temperature of 20°C (normal temperature) and a humidity of 65%.
00. ? ) Place three of each on a stainless steel plate and blow cold air at -35℃ for 30 minutes to remove moisture in the air inside the freezer and free water on the surface of each grain of cooked rice. When it condensed on the surface, tuna, and seaweed to form independent and strong frozen capsules, the center temperature reached 0°C.

Thereafter, when cold air at -75°C was blown for 20 minutes to rapidly cool the temperature, the center temperature became 18°C.

Next, blow cold air at -35℃ for 30 minutes to slowly lower the temperature to balance the outer circumference and center temperature, and bring the center temperature to -111℃.
℃.

To freeze the free water all at once, we blew cold air at 175°C for 15 minutes, resulting in a center temperature of 117° (J).

In order to freeze the solid water in micellar bonds, an additional 135
It was cooled for 30 minutes with cold air at -18°C, and when the center temperature reached 123°C, it was wrapped in a 40 μm thick polyethylene bag and transferred to a regular freezer at -18°C for one year.

Separately, the same amount of tuna nigiri sushi and nori sweet sushi were wrapped in Japanese paper, each grouped with 3 pieces, and treated with air freezing, airplast freezing, and contact freezing at 35°C for 24 hours, then wrapped in a 40 μm thick polyethylene bag. It was then transferred to a regular freezer at -18°C and stored for one year to serve as a control.

Next, the frozen sushi of the present invention and the control group were allowed to thaw naturally at room temperature of 25°C for 1 hour. Mutual adhesion, degree of gelatinization of cooked rice by gel coamylase method (
The quality retention was tested based on the maintenance of α-quality), the texture when eaten, the color of the sushi, etc., and the results shown in Table 4 were obtained. was maintained.

<Example 5> Three Noshimochi weighing about 100 g were each placed on a stainless steel plate in an atmosphere with a cooling box temperature of 22°C (room temperature) and a humidity of 65°C, and cold air at -35°C was blown for 30 minutes. Moisture in the air in the space inside the freezer and free water on the surface of the rice cake condense the surface three particles to form a strong capsule, each having a center temperature of 3°C.

Thereafter, when the sample was rapidly cooled by blowing cold air at -60°C for 20 minutes, the center temperature became -10°C.

Next, switch to -35°C cold air and cool slowly for 30 minutes to reduce the difference in temperature between the outer periphery and the center, and then further cool to -160°C.
Rapid cooling with cold air for 15 minutes completes crystallization of retained water without destroying the gelatinized micellar structure of the single polysaccharide.
Ta.

The core temperature was -17°C.

After switching to cold air at -35°C again and cooling for 30 minutes to bring the center temperature to -25°C, it was wrapped in a 40 μm thick polyethylene bag and transferred to a regular freezer at -18°C for one year.

Separately, three mochi mochi of the same amount were treated as a group with air freezing, airplast freezing, and contact freezing at -35°C for 24 hours, then wrapped in a 40 μm thick polyethylene bag and transferred to a regular freezer at -18°C. 1
It was stored for a year and used as a control plot.

Next, the frozen mochi of the present invention and the control group were allowed to thaw naturally at room temperature of 25°C for 1 hour, and the deformation and stability of the shape when pressed with a fingertip, the texture and color tone when eaten were evaluated. The quality retention characteristics were tested in terms of flavor and the like, and the results shown in Table 5 were obtained.The frozen mochi according to the present invention maintained a high quality close to that of fresh mochi for one afternoon.

Claims (1)

[Claims] 1. A freezing capsule forming process in which a frozen capsule is formed on the outer circumferential surface of the food to be frozen and the food is cooled so that the temperature at the center of the food is around 01°C to 3°C; then, the food passes through the maximum ice crystal formation zone in a difficult-to-freeze state. Creates a supercooled state that causes
A supercooling process in which the food core temperature is cooled to below 16°C; a slow cooling process in which the food is cooled to balance the outer temperature and center temperature; and cooling to form ice crystals in the food product. A method of freezing food that includes a freezing process.