JP3079261B2 - Thawing frozen foods - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for thawing frozen food. More specifically, the present invention relates to a method for thawing frozen food that can thaw in a short period of time while preventing the drip from being frozen from the frozen food.

[0002]

2. Description of the Related Art Fresh foods such as fish and shellfish such as tuna and meat can be kept frozen for a long time by keeping them fresh. The liquid juice of many of the frozen and preserved fresh foods is thawed at the time of thawing. This sap is called a drip and contains a high concentration of nutrient components in addition to flavor components and flavor components. Therefore, as the amount of drip that melts during thawing increases,
The amount of the umami component and the like that disappears from the food increases, leading to a decrease in the quality of the food.

Hitherto, in order to reduce the amount of drip that melts during thawing, thawing at a low temperature of about 5 ° C. has been recommended. Such low-temperature thawing is established as a thawing method with the least melting out of drip, especially for meat and the like, but has a problem that thawing takes a long time. Another way to reduce drip is to use 2
There is also a method of pre-thawing at a temperature of about 0 ° C. for several tens of minutes, followed by main thawing at about 5 ° C. This method can reduce the time required for thawing than the low-temperature thawing in which all the steps are performed at about 5 ° C., but has a disadvantage that it requires a longer time than thawing at room temperature. In order to further reduce the time required for thawing, thawing with a microwave oven and submerged thawing with running water at normal temperature have been attempted. However, in the method using a microwave oven, there are problems such as uneven thawing, and in thawing in liquid, there are problems such as elution of a soluble component into a liquid. I can't. In addition, in the case of thawing in liquid using running water, there is also an economical problem that costs are required for the tank and the amount of water.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a small amount of drip when thawing a frozen food, thereby reducing the quality of the food before freezing. It is an object of the present invention to provide a method for thawing frozen foods, in which a decrease in the temperature is suppressed and the time required for thawing is short.

[0005]

As a result of intensive studies, the present inventor has found that the above problem can be solved by using the following method. That is, the present invention relates to a method for thawing frozen food by heating, wherein (1)
A heat treatment step of forming a gel-like layer structure such that drip does not melt from the frozen food to be thawed only on the surface of the frozen food; and (2) thawing the frozen food obtained in the heat treatment step at a temperature around room temperature. A method of thawing frozen food, comprising the step of:

[0006] In the above-mentioned thawing method, the temperature of the heat treatment step can be set at about 70 ° C to about 90 ° C, and the time can be set at about 3 seconds to about 20 seconds.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the method for thawing frozen food of the present invention (hereinafter, also simply referred to as the "thawing method of the present invention") will be described in detail.

[0008] There is no particular limitation on the type of material of the frozen food to which the thawing method of the present invention can be applied, and it can be applied to any frozen food such as fish and shellfish, animal meat, vegetables, fruits, salads and processed foods. it can. The thawing method of the present invention can be preferably applied particularly to fish and shellfish, animal meat, and the like, which are likely to cause a drip problem.

[0009] The thawing method of the present invention comprises: (1) a heat treatment step of forming a gel-like layer structure such that drip does not melt from the frozen food to be thawed, only on the surface of the frozen food;
(2) The method further comprises a thawing step of thawing the frozen food obtained in the heat treatment step at a temperature around room temperature.

[0010] The gel-like layer structure provided on the surface of the food in the heat treatment step retains the moisture of the food held therein more than the layer structure, and the sap containing the umami component passes over the layer structure. Melting out of the food can be prevented. Furthermore, the present inventor has found the following phenomena, and by forming a gel-like layer structure only on the surface of the frozen food and suitably setting the subsequent thawing temperature, the present invention reduces the amount of drip in a short time. This is the method of decompression. Specifically, when an aqueous solution in which salt or glucose is dissolved is frozen around, as in the case of freezing in a refrigerator, although the solute is freeze-concentrated inside the ice, it is the thickest liquid at the beginning of thawing at the time of thawing. Was found to melt. On the other hand, when salt and glucose were dissolved in a gel such as agar instead of a solution, and then frozen and thawed, it was found that the melting pattern of the components was greatly dependent on the thawing temperature. That is,
In the case of a gel solution, when thawing at room temperature, as in the case of thawing a frozen aqueous solution, it melts from a component with a high concentration, but when thawing at a high temperature around 80 ° C, it first melts from a thin solution. I understood that.

Conventionally, it has not been known that dripping can be reduced by making the surface of the food to be thawed into a gel. In other words, in the method of thawing at about 5 ° C. after preliminary thawing at 20 ° C. as described in the section of the prior art described above, since the ice includes a part that is partially melted, the surface of the frozen body is immediately returned to the gel. It is not possible to keep water sufficiently. In addition, as a method of thawing and cooking frozen foods such as steaks and hamburgers, the protein on the surface is heat-treated by heating to a high temperature of, for example, about 180 ° C. while being frozen, and a layered product is formed on the surface of these foods. A method is known in which the drip is reduced by providing the above structure, and the outflow of components is reduced. However, the treatment at such a high temperature causes components of the frozen food such as protein to be completely denatured by heat and to be in a coagulated state.

On the other hand, in the thawing method of the present invention, the surface of the food is not completely solidified as in the above-described thawing method, but is made into a gel. Here, the gel state refers to a state in which the solution is uniformly dispersed in components forming a network structure such as agar.

When the surface is frozen, as in conventional methods, ice crystals form in the network of the gel, between which the solution components are concentrated and stagnate. Also,
In the solidified state in the hamburger example, the network structure is aggregated due to denaturation of the gel component due to high temperature, so that drip and elution of the constituent components are prevented. On the other hand, thawing at room temperature,
In the case of thawing in which the temperature is changed to 5 ° C. after 20 ° C., the freezing-concentration lowers the temperature, so that the components that have been frozen and concentrated are thawed, and the components are melted before the gel structure is completely restored. On the other hand, according to the present invention, by exposing to a high-temperature state for a short time, the gel structure on the surface of the frozen body is instantaneously restored, thereby preventing drip and melting of components due to its high water retention. It is. These effects are demonstrated in the examples section.

In the heat treatment step of the thawing method of the present invention,
A gel-like layer structure in which the drip does not melt from the frozen food to be thawed can be formed only on the surface of the frozen food by appropriately setting the temperature and time for heating the frozen food.

[0015] The temperature of the heat treatment step can vary depending on the type, physical properties, weight, freezing temperature and the like of the food material to be thawed.
For example, when about 15 g of fish meat frozen at −15 ° C. is thawed, the temperature of the heat treatment step can be set to about 70 ° C. to about 90 ° C., more preferably about 80 ° C. If the heat treatment temperature is too low, the gel structure does not completely return to the surface of the frozen body, and if it is too high, the product is denatured, which is not preferable. In addition, the temperature specified here means the temperature of the medium for heating described below, and is not the temperature of the surface of the frozen food to be thawed. Therefore, strictly speaking, the temperature may be lower than this temperature near the frozen food.

[0016] The time of the heat treatment step can be determined according to the type, physical properties, weight, freezing temperature, etc. of the food material to be thawed. When the above-mentioned fish meat is thawed, it takes about 3 seconds to about 20 seconds. Preferably, it can be set to 5 to 10 seconds. If the treatment time is too long, the gel structure is denatured. If the treatment time is too short, the gel structure is not sufficiently restored, which is not preferable.

In the heat treatment step, conditions other than temperature and time, such as humidity, are not particularly limited.
It can be set appropriately.

The heating in the heat treatment step can be performed by a method using a heating medium known per se (for example, thawing in heated gas or steam alone or in a mixed gas, immersion in hot water). it can. Those skilled in the art can appropriately select which method to heat according to the type, physical properties, weight, freezing temperature, etc. of the food material to be thawed.

In the heat treatment step, it is sometimes preferable to pack the frozen food in a plastic film or the like from the viewpoint of elution of the constituent components after melting.

In the thawing method of the present invention, the frozen food having the gel layer structure provided only on the surface thereof by subjecting to the heat treatment step is subjected to the thawing step of thawing at a temperature near room temperature.

Here, "around room temperature" means a temperature of about 5 to 40 ° C., usually 15 to 25 ° C., that is, a state in which no special temperature control is required. If the temperature of the thawing step is too low, the thawing time takes a long time, and if it is too high, the quality of the food is deteriorated, which is not preferable.

The time of the thawing step is determined by the type of frozen food to be used, the freezing temperature, the size, the shape (whether flat or massive), the purpose of use (whether to eat raw or to cook and then eat, etc.). ), May vary according to the taste of the eater, legal regulations, and the like. Those skilled in the art can easily understand how much the time of the thawing step itself can be set to achieve a desired thawing state. For example,
In order to defrost the above-mentioned fish meat, it can be set to about 20 minutes.

In the thawing step, conditions other than temperature and time, such as humidity, are not particularly limited, and those skilled in the art can appropriately set them.

The heating in the thawing step can be carried out by leaving the foodstuff which has undergone the heat treatment step at room temperature. If necessary, a method using a heating medium known per se (for example, mixing Thawing in gas, immersion in water)
Can also be performed.

In the thawing step of the present invention, it is sometimes preferable to package frozen food in a plastic film or the like from the viewpoint of preventing elution of components during high-temperature treatment.

[0026]

EXAMPLES The thawing method of the present invention will be described below with reference to examples, but the thawing method of the present invention is not limited to these examples.

<Example 1> Toro was frozen at -15 ° C,
Thawed using the thawing method of the present invention.

The experimental conditions were as follows. After 15 g of toro pieces were frozen, they were packaged in a vinyl chloride film and immersed in 80 ° C. hot water.
After a 5 second infiltration time, melting was performed at 20 ° C. and 5 ° C., respectively. As a comparison, 20 ° C without treatment at 80 ° C
And dissolution at 5 ° C only was also attempted.

FIG. 1 shows the weight loss after drip leakage after thawing under each condition. According to FIG.
It can be seen that the processing in step (1) greatly reduces the amount of drip. It can be seen that the drip amount is almost the same as the case of only the melting treatment at 5 ° C.

Example 2 80 g of hamachi was packaged in vinyl chloride and frozen at -15 ° C. Once
The thawing method of the present invention in which the treatment was carried out at 80 ° C. for 5 seconds and then left at 20 ° C., and the state of being constantly kept at 20 ° C. were studied. Thereafter, a sensory test was conducted on the appearance, texture, and taste of the two.

The results are summarized in Table 1. The evaluation was performed in five steps, with 1 being the lowest and 5 being the highest.

[0032]

[Table 1]

As is clear from Table 1 above, hamachi thawed using the thawing method of the present invention can obtain a better evaluation than the comparative sample in all evaluation items of appearance, texture and taste. did it.

Example 3 The time required for thawing frozen foods was compared. After freezing 50 g of toro at −15 ° C. and then thawing at various temperatures, the thawing time was examined.

As a result, when melting was performed only at 5 ° C., it took 5 hours to thaw. In the case of 20 ° C., it took 40 minutes.

On the other hand, the heat treatment step of 80 ° C. for 5 seconds and the thawing step at 20 ° C. of the present invention take 30 minutes,
In the case of the heat treatment step at 80 ° C. for 5 seconds and the thawing step at 5 ° C., thawing could be performed in 3 hours. In particular, according to the thawing method of the present invention in which the thawing step was set at 20 ° C., as shown in Example 1, the amount of drip of the thawed food was comparable to that at 5 ° C. The time is 1
It can be seen that it can be shortened to / 10.

[0037]

As described above, by using the thawing method of the present invention, the thawing of the drip is small, and the thawing can be performed in a short time while suppressing the deterioration of the quality due to the thawing. Due to the short time required for thawing, work efficiency is increased, and in addition to the economic advantage of lowering costs,
There is also a hygienic advantage, as the time to be affected by microorganisms, enzymes, air and the like is short.

Further, since the thawing method of the present invention can be carried out by combining known devices per se, another economical method that does not require the manufacture of a new device for carrying out the present invention is provided. There are advantages too.

[Brief description of the drawings]

FIG. 1 is a graph comparing the amounts of dripping of frozen toro thawed by different thawing methods under different conditions.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A23L 3/365 A23B 4/07 A23B 7/04 A23L 1/00-1/035

Claims (3)

(57) [Claims] 1. A method for thawing frozen food by heating, wherein (1) a heat treatment step of forming a gel-like layered structure only on the surface of the frozen food so that drip does not melt from the frozen food to be thawed. Temperature and time of the heat treatment step
But about 70 ° C. to about 90 ° C. and about 3 seconds or more, respectively.
A method for thawing frozen food, comprising : a step of not more than 20 seconds ; and (2) a thawing step of thawing the frozen food obtained in the heat treatment step at a temperature around room temperature. 2. The method according to claim 1, wherein the temperature of the heat treatment step is such that frozen food is added.
2. The method according to claim 1, wherein the temperature is the temperature of the medium used for heating.
How to unpack. 3. The method of claim 1, wherein said heat treating step is performed at a temperature of about -15.degree.
The method according to claim 1, wherein the method is applied to fish meat that has been cut.
Or the thawing method described in 2.