JPH0636723B2 - How to cool cooked rice - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for cooling cooked rice in which freshly cooked cooked rice is rapidly cooled while reducing the decrease in its weight as much as possible.

[Prior art]

In recent years, cooked rice cooked by specialists has been increasingly used for general people's meals. However, these cooked rice are sold at a high temperature of 60 ° C or higher, or at room temperature. It's either like an ekiben that sells items that have been cooled down to the side with side dishes.

On the other hand, for cooked vegetables such as ekiben, which are sold in the state of being cooled to room temperature, it is necessary to cool the cooked food to 10 ° C or less as quickly as possible. In the above, the temperature range of 30 to 40 ° C. must be passed, but this temperature range is the temperature at which fungi are most likely to grow, and it is necessary for food to pass this temperature in the shortest possible time. is there.

As a cooling method, in the past, a small amount of air was blown with an electric fan to cool it.However, this requires a large space for cooling, and it also spoils air in the room, rather causing decay. It will result in spraying bacteria etc.,
This is an unfavorable method.

Therefore, a vacuum cooling method has been developed, which is a method in which the delicatessen is put in a closed container and the inside is decompressed by a vacuum pump, and water is cooled by self-evaporation to a temperature according to the degree of vacuum.

Ordinary water has a temperature of about 18 Torr and a temperature of 20 ° C, but in the case of delicatessen, it has saltiness, so it is necessary to raise the vacuum degree a little more.

In addition, cooked rice has a starchy substance unlike ordinary cooked vegetables, so if it is cooled to too low a temperature, the taste will be lost, so it is better to keep it at about 20 ° C.

As an advantage of the method of cooling by vacuum as described above,
Moisture evaporates from the entire interior to be cooled, so that the whole becomes a uniform temperature, and furthermore, the inside is contaminated at all because it is cooled by sucking the inside with a vacuum pump. Is.

However, when cooling is completed and the vacuum is broken, outside air is introduced, so it is necessary to put a filter capable of sterilizing in that passage.

Although the vacuum cooling method is a very good method as described above, the only drawback is that it is cooled by self-evaporation, which is not so important because it is based on the principle.

In general cooked vegetables, since the amount of water and juiciness is large, it is possible to reduce the amount of water to some extent, but in the case of cooked rice, if the amount of water is reduced excessively, the rice grains will become hard.

That is, if you cook freshly cooked rice from 80 ℃ to 20 ℃,
Since the weight is reduced by 4 to 4.5%, there is a problem that the mouth feel becomes very bad when it is put in the mouth.

[Object of the Invention]

An object of the present invention is to solve the drawbacks of the conventional cooling method of cooked rice that is cooled to room temperature and to provide a safe method of cooling cooked rice that is easy to eat and is not easily spoiled.

[Structure of Invention]

The method for cooling cooked rice of the present invention to achieve the above object is characterized in that, at the time of cooling freshly cooked cooked rice, first, cold air is blown onto the surface of the cooked rice to cool it, followed by vacuum cooling. is there.

〔Example〕

An embodiment of a cooker for a cooked rice to which the method for cooling cooked rice of the present invention can be applied will be described below with reference to the drawings, and the inside of the cooler 1 shown in the figure is divided into multiple stages. A drip-proof roof 2 and a cold air blow-out tube 3 for setting trays 10 for putting cooked rice on each stage are provided.

The cooler 1 has a header 4 and a return header 5 of a cold air blowing pipe 3 on both sides, which are connected to a cold air circulation blower 6, a heat exchanger 7 and an air filter 8.

A brine tank 11 and brine pumps 12 and 14 connected to a refrigerator 13 are connected to the heat exchanger 7 and are constantly cooled to about 5 ° C.

Next, the cooling procedure of the cooked rice by the cooler 1 will be explained. First, the cooked cooked rice is put into the tray 10, while the cooked rice in the tray 10 is naturally cooled to about 80 ° C.

The vapor scattering at this time also occurs when cooking rice in a general household, and this removes excess water and improves the taste when eaten.

The problem is cooling from now on, and when this tray 10 is suddenly put into a vacuum cooler as in the conventional case, it is cooled rapidly in accordance with the capacity of the vacuum pump, but at that time the temperature is 80 ° C.
The amount of water required to lower the temperature from 20 ° C to 20 ° C will flow into the vacuum pump.

On the other hand, according to the cooling method of the present invention, the tray 10 containing the cooked rice at 80 ° C. is placed in the cooler 1, and the drip-proof roof 2 and the cold air blowing pipe 3 are set in each tray 10, When the cold air circulation blower 6 is started, the air cooled to 10 ° C. or less is blown to each tray 10 from the cold air blowing pipe 3,
Cooling air passes between the cooked rice and the tray 10 and escapes from the bottom.

During this time, the temperature of all the parts of the cooked rice exposed to the cold air drops, and the evaporation of water does not proceed any further, but the parts of the cooked rice block that are not exposed to the cool air are still kept at high temperatures.

Here, the cooling air needs to be sent to the cooked rice after being sterilized by the air filter 8 having a sterilizing ability.

When the surface temperature of the cooked rice fell below 20 ° C., the circulation of cold air was stopped, the tray 10 was taken out, put in a vacuum cooler (not shown), and about 18 Tor in a normal manner.
Vacuum is performed by drawing a vacuum up to r.

As a result, the vapor self-evaporated from the inside of the cooked rice is trapped in the low temperature portion of the outer surface, raises the temperature and replenishes moisture, becomes saturated vapor of the degree of vacuum, and is drawn out by the vacuum pump to go out.

Therefore, if the vacuum degree is maintained at about 18 Torr for several minutes to break the vacuum, the whole cooked rice inside is uniformly cooled to about 20 ° C. and taken out.

In the above description of the embodiment, the cooler 1 and the vacuum cooler are described as separate bodies, but the cooler 1 and the vacuum cooler may have an integrated structure in which a part thereof is also used. The cooling method of the present invention can be effectively applied.

〔The invention's effect〕

As described above, according to the method for cooling cooked rice of the present invention, the total amount of water loss during cooling with cold air and the subsequent water loss due to vacuum cooling is 2.0 to 2.3%. Weight loss is limited to about half that of the conventional case where only vacuum cooling is performed from the beginning, and the reduction in weight due to cooling can be reduced, and the texture when rice is put in the mouth is greatly improved. It is extremely effective in improving the taste of.

Further, if the cooked rice is cooled using the method of the present invention, the cooked rice can be cooled promptly and the chances of breeding of fungi are reduced, so that safe cooked rice that is resistant to decay can be provided.

[Brief description of drawings]

The drawings are cross-sectional views showing an embodiment of a cooler to which the method for cooling cooked rice of the present invention can be applied. 1 ... Cooler, 3 ... Cold air blowing pipe, 7 ... Heat exchanger, 10 ... Tray, 13 ... Refrigerator.

Claims (1)

[Claims] 1. A method of cooling cooked rice, which comprises first cooling the freshly cooked cooked rice by blowing cold air onto the surface of the cooked rice and then vacuum cooling.