JPS60105478A - Method and apparatus for thawing frozen food - Google Patents

Abstract

PURPOSE:To enable almost uniform thawing of a frozen food, and obtain a thawed food having extremely high quality, by thawing the frozen food under irradiation of microwave while cooling the surface of the frozen food. CONSTITUTION:The microwave irradiation chamber 4 is attached to the transfer conveyor 1 of a frozen food, and a chilled air blower 8 is placed at a proper part of the irradiation chamber 4. The frozen food is thawed by the irradiation of microwave while cooling the surface of the frozen food. As a result, the whole frozen food can be thawed uniformly, and a thawed food having extremely high quality can be produced. The cooling of the surface of the frozen food is also effective to keep the freshness, color, taste, etc. of the food, and suppress the proliferation of bacteria.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for preventing deterioration in the quality of frozen foods when thawing them using microwaves.

Microwaves are used to quickly thaw frozen foods that have been frozen at -20 to 30C. It thaws quickly, making it difficult to thaw the whole thing uniformly.Also, even if there are no sharp parts, the thawed moisture is exposed on the surface of the thawed object, and this exposed moisture is exposed to microwaves. Due to the intensive application of energy, the surface temperature becomes significantly higher than the internal temperature, and when the food is thawed to the inside, the surface becomes dry and becomes unsuitable for cooking, resulting in the defect that the entire food cannot be thawed evenly. be.

That is, the inventor made frozen walleye surimi blocks (2,
When we measured the temperature distribution inside the block when a block (3 cm x 20 crn There is a temperature difference that reaches
It turned out that the whole thing could not be defrosted evenly.

However, when a frozen surimi block was kept at a low temperature of 15'CJ and thawed while cooling the surface.

As shown in Figure 2, the temperature distribution is almost even between the inside and outside, and the temperature difference between the inside and outside is as small as 3.1 degrees.
We succeeded in obtaining thawed food of extremely high quality.

Furthermore, cooling the surface of frozen foods in this manner has the advantage that the freshness, color, taste, etc. of the foods are not impaired, and the generation of bacteria can be suppressed.

The present invention has been made to improve the defects of the conventional technology based on such knowledge, and includes irradiating the frozen food with microwaves and thawing the frozen food while simultaneously cooling the surface of the frozen food, and irradiating the conveyor of the frozen food with microwaves. The main feature is that a cooling air generator is provided at an appropriate location in the microwave irradiation chamber.

The microwave irradiated in the present invention uses a commonly used oscillation frequency of 2,450 MHz, and the center temperature of the frozen food, which is usually frozen at -20C or higher, is about O to -3C, which is necessary for thawing. The irradiation time depends on the type of frozen food, freezing temperature,
Appropriate adjustment may be made depending on the size, etc., and at this time, the cooling means for the frozen food is thawed by maintaining the room temperature in the thawing chamber at -5 to -15C1, preferably around -7C.

FIGS. 3 and 4 show an example of a thawing apparatus that implements the thawing method of the present invention. That is, a transfer conveyor (1) made of Teflon, stainless steel, etc. for transferring frozen foods has an entrance/exit (31 (3)) having microwave absorbers (2) at both ends.
) is provided, the microwave irradiation chamber (4) is connected to a microwave oscillation device (6) through a waveguide (5), and a master microwave irradiation chamber is provided. At the front of (4) is a cooling device (
8) is installed, and the cooling fan (9) distributes cooling air (3).
) It is configured so that air can be blown to the rear of the chroma wave irradiation chamber (4). Note that (10) in the figure is a shutter used when the transfer conveyor (1) is stopped and defrosting is performed in a batch manner, and (111 is an exhaust pipe having a punch plate a2 to prevent leakage of microwaves).

Example 1 20t7IC frozen walleye surimi block (
2,3crrIX 20crrIX 40cm) 2
9 in a thawing chamber maintained at -70 and 2450 MHz.
When the block was thawed by irradiation with microwaves with an output of 5KW for 12 minutes, the center temperature of the block was -1, and the surface temperature of 5C1 was 1.5.
And.

We were able to obtain high quality raw materials for fish paste products.

As described above, according to the present invention, the whole frozen food can be thawed almost uniformly using microwaves, and the freshness, color, taste, etc. of the food can be thawed without deteriorating, and extremely high-quality thawed food can be produced.

[Brief explanation of drawings]

(4) Figure 1 is a temperature distribution diagram in a cross section of a frozen food according to the conventional method, Figure 2 is a temperature distribution diagram in a cross section of a frozen food according to the present invention, Figure 3 is a partially cutaway front view of the apparatus of the present invention, and Figure 4 The figure is a longitudinal side view of the same. (1)...Transfer conveyor, f4)...Microwave irradiation chamber. (8)...Cooling device. Patent applicant Bibun Co., Ltd. Figure 2 Figure 3WJ ill [1411

Claims (1)

[Claims] 1. A method for thawing frozen food, characterized by irradiating the frozen food with microwaves and thawing the frozen food while cooling the surface of the food at the same time. 2. A thawing device for frozen foods, which is provided with a microwave irradiation chamber on a conveyor for transferring frozen foods, and a cooling air generator is installed at an appropriate location in the microwave irradiation chamber.