JPH104942A - Thawing of frozen food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for thawing a frozen food designed to irradiate the food except ices with microwave to raise its temperature to a specified level followed by ending the microwave irradiation so as to prevent heating unevenness development, partial scorching or deterioration of the food after thawed and thus facilitate its secondary processing after thawed. SOLUTION: A frozen food (except ices) at <-18 deg.C is unloaded from a relevant storehouse, irradiated with microwave and thawed to effect raising its temperature to -18 to -1 deg.C (pref. -3 to -1 deg.C) followed by ending the microwave irradiation. The temperature range of -3 to -1 deg.C corresponds to the ice temperature region; and if the frozen food after thawed is preserved while keeping the above temperature range, it can be preserved in a favorably fresh state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for thawing frozen food. More specifically, the present invention relates to a method for removing frozen foods other than frozen desserts stored in a storage at a temperature of less than -18 ° C from the storage, irradiating with microwaves, defrosting the frozen foods, and reducing the temperature of the frozen foods to -18 ° C. In the range of -1 ° C, preferably-
The present invention relates to a method for thawing frozen foods, which comprises raising the temperature to a predetermined temperature in the range of 3 ° C to -1 ° C and terminating microwave irradiation.

[0002] In the present invention, the frozen food is a frozen dessert (manufactured by a conventional method using a freezer and subjected to a hardening treatment). ), And can be exemplified by frozen cakes, frozen tuna, and the like.

[0003]

2. Description of the Related Art In general, frozen foods are foods in which food materials, cooked foods and the like are rapidly cooled and frozen, and the preservation thereof is improved by lowering the product temperature to a temperature of less than -18 ° C. It is rapidly becoming popular with changes in style.

[0004] When eating frozen foods, they are thawed,
Examples of the thawing method include a method of leaving frozen food in a refrigerator, a method of immersing it in water, a slow thawing method, a method of thawing frozen food as it is, a quick thawing method of thawing in a short time, and the like.
There are various methods.

[0005] Among the rapid thawing methods, a method using microwaves (hereinafter referred to as a microwave thawing method) is considered to be a particularly excellent method because it can thaw in a short time without deteriorating the quality of frozen food. ing. Frozen foods are usually
It is stored in a storage below 18 ° C., and the product temperature is also about the same. However, in the microwave thawing method, the temperature is reduced to room temperature (20-30 ° C.) in a short time, or even higher ( The fact that the temperature can be increased to 90 to 100 ° C.) is considered to be a great advantage.

[0006]

However, in general, when the physical properties of water and ice are compared, each of them has a different calorific value when irradiated with microwaves. Therefore, in the conventional microwave thawing method, there is a problem that a large difference occurs in the calorific value between the previously thawed portion and the unthawed portion inside the frozen food, and the temperature of the previously thawed portion rapidly rises. Was.
That is, when non-uniform heating occurs during thawing and the temperature of the frozen food is raised to room temperature, there are problems such as partial burning and deterioration. Such a problem tends to be prominent especially when the size of the frozen food is large.

Further, for example, when the frozen food after being thawed is processed secondarily, for example, when the cuts of raw fish are cut into sashimi, no matter how sharp the knife is used, the cutting method is not good. In general, frozen food softened by thawing tends to be technically difficult to perform secondary processing such as cutting, for example, so that a difference in finish is caused due to this.

An object of the present invention is to eliminate the occurrence of uneven heating,
An object of the present invention is to provide a method for thawing frozen food, which does not cause partial burning or partial deterioration of the food after thawing, and facilitates secondary processing of the food after thawing.

[0009]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems is directed to removing frozen foods except frozen desserts stored in a storage at a temperature of less than -18 ° C from the storage and irradiating them with microwaves. Thaw and raise the temperature of the frozen food to -18 ° C
A method for thawing frozen foods, comprising raising the temperature to a predetermined temperature in a range of -1 ° C and terminating microwave irradiation, wherein the predetermined temperature is in a range of -3 ° C to -1 ° C. This is a desirable mode.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, first,
The frozen food stored in the storage at a temperature lower than -18 ° C is removed from the storage. Here, the storage includes all facilities for storing frozen foods at a temperature of less than -18 ° C, such as a freezing warehouse, a freezing delivery vehicle, a freezing case, and the like.

Next, microwaves are applied to the taken out frozen food. The temperature of frozen foods rapidly rises in a short time due to microwaves. In the present invention, the microwave irradiation is terminated when the temperature of the frozen food reaches a predetermined temperature of -18 ° C or higher and -1 ° C or lower. That is, usually
When the temperature is raised to normal temperature (20 to 30 ° C.) or even higher (90 to 100 ° C.) depending on the type, in the present invention, the thawing operation by microwave is performed when the temperature is raised to a predetermined temperature of −1 ° C. or less. Let it end.

Therefore, since the temperature is raised to an appropriate temperature of -1 ° C. or less, unevenness in heating of the frozen food does not occur, and there is no burning or deterioration of a part of the thawed food. . Further, if the temperature is raised to a temperature at which the hardness becomes appropriate, the food product after the thawing operation can be easily cut, and the secondary processing becomes easy.

[0013] The frozen food thawed by the method of the present invention comprises:
It may be stored in the refrigerator as it is and thawed more slowly, but it may be cooked immediately, or if it is cut and eaten as it is, it is possible to taste a food with a cold texture.

A preferred embodiment of the present invention is that the temperature is -3.degree.
Terminating the microwave irradiation at the time when the temperature is raised to a predetermined temperature of not more than ° C. The temperature range of −3 ° C. to −1 ° C. is a temperature at which thawing by microwaves has greatly progressed, but also a temperature immediately before the food is scorched or deteriorated due to uneven heating. And -3 ° C or higher and -1 ° C
The following temperature range is the ice temperature range, and if the frozen food after thawing is stored in that temperature range, it can be stored with good freshness.

[0015]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples.

Example 1 (1) Preparation of frozen food Four frozen tuna cuts (commercially available) of 550 g to 700 g were stored in a freezer at -30 ° C for one week.

(2) Thawing Immediately after the completely hardened frozen tuna fillet was taken out of the freezer, it was impossible to cut it with a kitchen knife. Each of the frozen tuna fillets was placed in a microwave range (manufactured by Matsushita Electric Industrial Co., Ltd., NE-DF50), and 800
Microwave irradiation with W for 15 seconds. As a result of inserting a thermocouple thermometer into each place of each cut after irradiation and measuring the temperature,
Each location was in the range of −5 ° C. to −3 ° C., and it was confirmed that the entire fillet was uniformly heated.

(3) Secondary Processing The slices after thawing were cut with a sashimi knife, but the slices were cut smoothly and the cut surfaces were smooth.
In addition, when it was eaten in soy sauce, the cold texture was refreshing, and no partial alteration due to overheating of the microwave was observed.

Comparative Example (1) Preparation of Frozen Food One frozen tuna fillet (commercially available) similar to that of Example 1 was used.
It was stored in a freezer at −30 ° C. for one week.

(2) Thawing The frozen tuna fillet was placed in a microwave range (NE-DF50, manufactured by Matsushita Electric Industrial Co., Ltd.) and irradiated with microwaves at 800 W for 45 seconds. After irradiation, a thermocouple thermometer was inserted into each part of the fillet and the temperature was measured.
１５15 ° C.

(3) Secondary Processing The cut after the completion of thawing was cut with a sashimi knife, but the cut was too soft to cut easily, and the cut surface was finely cut. In addition, when it was eaten in soy sauce, the texture was poor, and part of the texture was altered by overheating with microwaves.

As is clear from comparison with Example 1, it is confirmed that the thawing method of the present invention does not deteriorate the original flavor of the frozen food, and is easy to cut after thawing. Was.

Example 2 (1) Preparation of frozen food 700 g of round frozen cake was stored in a freezer at -30 ° C for 3 days.

(2) Thawing The round frozen cake was taken out of the freezer.
The surface was extremely hardened and could not be cut with a kitchen knife. The round frozen cake was placed in a microwave range (NE-DF50, manufactured by Matsushita Electric Industrial Co., Ltd.) and
Microwave irradiation was performed at 00 W for 20 seconds. After the irradiation, a thermocouple thermometer was inserted into each place and the temperature was measured. As a result, it was confirmed that all places were in the range of -3 ° C to -1 ° C, and the entire cake was uniformly heated. Was.

(3) Secondary processing When the cake after the thawing was completed was cut with a kitchen knife, the kitchen knife passed smoothly and the cut surface was smooth. In addition, when it was eaten, the cold texture was refreshing, and no partial alteration due to overheating of the microwave was observed. A part was stored in a refrigerator at −2 ° C. for 2 days and ate, but the flavor did not change.

As a result, it was confirmed that, in the present invention, if thawing was performed in the range of -3 ° C. to -1 ° C., the storage stability after that was good.

[0027]

According to the method for thawing frozen food of the present invention,
There is no heating unevenness, there is no partial scorching or deterioration of the food after thawing, and it is easy to perform secondary processing of the food.

Claims (2)

[Claims] 1. A frozen food excluding frozen desserts stored in a storage at a temperature of less than −18 ° C. is taken out from the storage, thawed by microwave irradiation, and the temperature of the frozen food is lowered to −18 ° C.
A method for thawing frozen foods, comprising raising the temperature to a predetermined temperature in the range of -1 ° C and terminating microwave irradiation. 2. The method for thawing frozen food according to claim 1, wherein the predetermined temperature is in a range of -3 ° C. to -1 ° C.