JPH07106135B2 - Freezing method of food - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for freezing a food, in which water on the surface and inside of the food is instantly frozen so that deterioration of the quality of the food due to freezing can be suppressed to an extremely small level. It is about.

[Prior Art] Food is usually cooled by lowering the temperature of the food to 0 ° C. or lower to freeze the water in the food. As a freezing device therefor, an air blast type, a contact type, Various types of freezing devices such as fluidized freezing type and liquid nitrogen type are used.

[Problems to be solved by the invention]

However, even if the food is frozen by the freezing device as described above, it takes a long time until the food is completely frozen.
Especially, it takes several hours to freeze a large food such as tuna to its central portion.

When freezing takes a long time in this way, the temperature in the food slowly passes through the freezing temperature zone, so the ice crystals formed in the food physically and irreversibly destroy the tissue of the food and To grow greatly. Therefore, when the food is thawed, the food does not restore to the tissue before freezing, and the taste, color, and odor are indirectly adversely affected as well as the texture and water retention.

Due to the recent development of the rapid freezing method, such problems are
Although it is being mitigated, satisfactory results have not yet been obtained.

Therefore, an object of the present invention is to provide a novel food freezing method capable of suppressing the deterioration of the quality of the food at the time of thawing by freezing to be extremely small by instantaneously freezing the water on the surface and inside of the food. is there.

[Means for solving problems]

The present invention, after the food has been cooled while isotropically pressurized with the pressure of 10~3000Kg / cm ^2, characterized in that to rapidly freeze the buck to the food at a decompression rate 200Kg / cm ² · min or more The above objects have been achieved by providing a method for freezing foods.

Hereinafter, the method for freezing food according to the present invention will be described in detail.

The food frozen by the freezing method of the food of the present invention is not particularly limited, and examples thereof include seafood, vegetables, fruits, livestock meat, processed foods thereof, etc., but isotropic pressing is preferred. Examples include foods with little deformation, and those with little or no deterioration in quality, value, etc. even if deformation occurs.

Thus, in order to carry out the freezing method of the food of the present invention, first,
The food is cooled while being isotropically pressurized at a pressure of 10 to 3000 Kg / cm ² . The isotropic pressurization may be performed, for example, by sealing the food in a pressure resistant container. The object of the present invention cannot be achieved when this pressure is not isotropically applied but, for example, when the pressure is unidirectionally applied using a contact freezer. Further, if the isotropic pressure is less than 10 kg / cm ² , the food is likely to be frozen due to cooling during pressure, and the case of more than 3000 kg / cm ² is also the same, which is not preferable. The cooling temperature is
Although it varies depending on the food, it is preferable to select it in a range where the temperature of the food does not rise during pressurization and the food is not frozen, usually 15 to -20 ° C, preferably 0 to -20 ° C. Just do it. If the cooling temperature is higher than 15 ° C, the quality of the food product is likely to deteriorate due to heat during pressurization, while if it is lower than -20 ° C, the food product is likely to be frozen during pressurization.
Further, even after completion of pressurization, it is preferable to continue cooling for a certain period of time while maintaining this pressurized state to cool the surface and inside of the food product to a substantially uniform temperature.

Then, the pressure is reduced to normal pressure at a decompression rate of 200 kg / cm ² · min or more to rapidly freeze the water on the surface and inside the food. If the depressurization rate is less than 200 kg / cm ² · min, freezing cannot be performed rapidly and the ice crystals in the food grow large, so that the quality of the food cannot be maintained.

The frozen (frozen) food obtained in this way has a tissue destruction time during freezing because the passage time in the freezing temperature zone during freezing is 1/10 or less of that of the conventional method and the growth of ice crystals has hardly progressed. Is extremely small, and therefore deterioration in quality during thawing can be suppressed to an extremely small level.

〔Example〕

Next, the method for freezing food according to the present invention will be described more specifically with reference to examples.

Example 1 Fillet of yellowtail was put in a pressure resistant container, pressurized to 2000 Kg / cm ² while cooling the inside of the container to −5 ° C., and kept for 15 minutes as it is, and then to a normal pressure at a decompression rate of 1000 Kg / cm ² · min. I stepped down. By this process, the fillets of Hamachi were completely frozen.

When the frozen fillet of Hamachi was thawed, cooked into sashimi and eaten, it was very delicious. That is, the color, taste, and smell were the same as the raw ones. In particular, the texture was the same as that of the raw one, and the texture was good.

Example 2 A frozen product of fillet of yellowtail frozen according to Example 1 was used.
After storing at 30 ° C. for 6 months, it was thawed, cooked into sashimi and eaten (test section).

Further, as a control, the fillet of Hamachi frozen in a contact freezer was similarly stored at -30 ° C for 6 months, then thawed and cooked into sashimi to eat (control).

As a result, the sashimi in the test section had a much smaller amount of drip than that in the control section, and retained water well.
Also, the texture is slightly lacking in smoothness in the control area,
A slight oily odor was also felt, but in the test area, it was almost the same as the raw one, the texture was very good, and no oily odor was observed.

Example 3 Kamaboko was placed in a pressure-resistant container, the pressure inside the container was increased to 2500 Kg / cm ² while being cooled to −10 ° C., and the pressure was maintained for 15 minutes, and then the pressure was reduced to normal pressure at a decompression rate of 2000 Kg / cm ² · min. , Frozen the kamaboko. The frozen kamaboko was stored at −30 ° C. for 6 months and then thawed to perform a sensory test (test section).

In addition, as a control, kamaboko frozen by air blast was similarly stored at −30 ° C. for 6 months and then thawed for sensory test (control group).

As a result, the control area had a slightly crunchy texture, and when it was bent, the internal water leached out,
The test plots retained a supple texture and almost no leaching of water was observed.

Example 4 A bunch of about 10 g of one grain was put in a pressure resistant container, pressurized to 2000 Kg / cm ² while cooling the inside of the container to −5 ° C., and kept as it was.
After holding for 15 minutes, the pressure was reduced to normal pressure at a decompression rate of 2000 kg / cm ² · min to freeze the grapes. Frozen grapes -30
After storing at C for 3 months, it was thawed and sensory-tested.

As a result, the taste and smell of thawed grapes were almost the same as those before freezing. In addition, the texture of the raw grapes remained, and the texture was also favorable.

Example 5 Two carrots (about 100 g each) were flash-frozen in the same manner as in Example 4, stored at -30 ° C for 3 months, and then thawed for sensory evaluation.

As a result, the taste, color, odor, and texture of the thawed carrots were the same as those in the raw state. Moreover, it was very delicious even when it was eaten raw as a salad material.

〔The invention's effect〕

The freezing method of the food of the present invention can suppress the growth of ice crystals in the food to an extremely small amount by instantaneously freezing the water on the surface and inside of the food by rapid pressure reduction after pressure cooling, According to the method of freezing foods, the destruction of food tissues due to ice growth is suppressed and the deterioration of the quality of foods upon thawing due to freezing is minimized, and the tissues after thawing are very close to the tissues of raw foods before freezing. Not only can frozen foods be produced, but frozen foods that have been difficult to store frozen can be frozen.

Claims (3)

[Claims] 1. A After cooling while applying isotropically pressurized with a pressure of 10~3000Kg / cm ² food, and characterized in that to rapidly freeze the buck to the food at a decompression rate 200Kg / cm ² · min or more Freezing method for food. 2. The method for freezing food according to claim 1, wherein cooling is performed at a temperature at which the food does not freeze. 3. The method for freezing food according to claim 1, wherein the pressure is reduced to atmospheric pressure.