JPH09172992A - Preparation of asepticaly packed cooked rice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a completely disinfected cooked and packed rice by exterminating thermoresistant microorganisms as well as general microorganisms. SOLUTION: A definite amount of washed and water-soaked rice is filled in a tray for one meal and heated in a closed chamber with a pressurized hot saturated steam to effect the sterilization treatment and the gelatinization of the rice. The gelatinized rice is added with cooking water, cooked and sealed in the tray with a covering material. The sterilization treatment is preferably carried out by intermittently flushing the pressurized hot saturated steam to the rice filled in the tray for one meal, e.g. flushing the pressurized hot steam for 5-10sec and repeating the cycle 6-8 times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing aseptic packed cooked rice, and more particularly to the manufacture of packed cooked rice which can completely sterilize not only general viable bacteria but also thermophilic viable bacteria. Regarding the method.

[0002]

2. Description of the Related Art So-called retort foods are known as aseptic packed foods. This is produced by filling a container with food such as cooked rice and sealing it, and then sterilizing it under high temperature and high pressure conditions. It can be completely destroyed.

However, since heat is gradually transferred from the periphery of the packed food to the center thereof, when the temperature of the center of the food reaches 130 ° C., the temperature of the surroundings is considerably higher than that, and the taste is improved. However, there was a problem in that When the retort sterilization is performed without losing the taste, the temperature of the central portion does not reach the predetermined temperature, so that complete sterilization cannot be realized.

As described above, it is practically difficult to completely sterilize a retort food product without losing its taste. Therefore, many attempts have been made to realize this by a method other than the retort food.

The rice cooking methods conventionally proposed for producing aseptic packed cooked rice include a multi-meal pot rice cooking method, an individual meal pot rice cooking method, and an individual meal tray rice cooking method.

[0006] In the multi-meal pot rice cooking method, the washed and soaked rice is 5
After filling a pot of ~ 15kg with water, continuously cooking and steaming gas, loosen it in a clean room, machine-paste it into a container that has been UV sterilized, and attach a UV sterilized oxygen scavenger. The container is then sealed with a UV-sterilized lid. The cleanliness in a clean room requires a class of about 100 to 1000.

[0007] In the individual meal cooker method, the washed and soaked rice is filled into a special cooker for each meal, water is added, and gas cooked and steamed continuously, and then loosened in a clean room.
The container is transferred to a UV-sterilized container by a machine, a UV-sterilized oxygen absorber is attached, and the container is sealed with a UV-sterilized lid. In this case as well, the cleanliness in the clean room requires a class of about 100 to 1000.

In the individual meal tray rice cooking method, the washed and soaked rice is directly filled in a plastic tray for each meal, sterilized under pressure, then poured into a steam rice cooker, continuously cooked, and UV sterilized. After sealing with a lid, the container is inverted and steamed, further steamed and then inverted again, and the container is discharged from the rice cooker. The process from the rice cooker outlet to the hermetic sealing is performed in a clean booth with a cleanliness of 100 to 1000 class.

[0009]

However, in the multi-meal cooker rice cooking method and the individual meal cooker rice cooking method, many steps are required to be performed in a clean room, and equipment and management for that are required. Since cleaning or sanitizing is required every time workers come in and out at the end of work and during working hours, the operating rate is lowered and the product cost is significantly increased.

On the other hand, in the case of the individual meal tray rice cooking method, since it is sufficient to make the process part from the rice cooker outlet to the hermetic seal a clean booth, the above problems hardly occur and the facility There is an advantage in terms of cost.

However, even in the case of the individual meal tray cooking method, in order to prevent oxygen in the container by removing oxygen in the container and prevent secondary contamination by aerobic bacteria and mold, an oxygen absorber is used. It is necessary to enclose (so-called ageless) in the container. Further, the container is required to have a gas barrier property, and in order to satisfy this, a relatively expensive EVAL resin or polypropylene multi-layered one must be used, which increases the product cost.

[0012] Furthermore, in any of the methods, general live bacteria die almost completely during rice cooking, but there is no step for treating heat-resistant live bacteria adhering to raw materials,
It was impossible to produce completely aseptic packed cooked rice that kills heat-resistant live bacteria by any conventional method.

[0013]

SUMMARY OF THE INVENTION Therefore, the present invention provides a completely sterilized packed cooked rice that kills not only general live bacteria but also heat-resistant live bacteria while making the most of the advantage of the conventional individual tray rice cooking system. It is an object to provide a novel method that can be manufactured.

That is, in the method for producing aseptic packed cooked rice according to the present invention, the rice that has been washed and soaked is filled in an individual food tray, sterilized by high-pressure high-temperature saturated steam in a closed chamber, and at the same time the rice is made into alpha, and then cooking water is poured. After the rice is cooked, the lid material is attached to the individual food tray and hermetically sealed.

In the present invention, it is preferable to sterilize the rice packed in the individual food tray by intermittently flushing high-pressure high-temperature saturated steam. For example, sterilization is performed by repeating high-pressure high-temperature saturated steam flushing for 5 to 10 seconds as one cycle 6 to 8 times. As a result, the sterilization time for rice can be shortened, and a sufficient sterilization effect can be obtained without impairing the taste of rice.

In this case, in order to prevent the rice packed in the tray from being scattered by the intermittent flushing of the high-pressure high-temperature saturated steam, the tray opening is provided with a plate having a substantially honeycomb shape in the closed chamber. It is preferable to coat with a member.

In the present invention, it is preferable to cook rice with a steam rice cooker. As a result, the rice cooking process can be made efficient as a rice cooker having a three-dimensional structure in which the multi-row, multi-stage gondola circulates in the steam chamber.

Further, it is preferable that the steps from the rice cooking to the completion of the hermetic sealing are performed in a clean booth. The clean booth has a cleanliness of about 100 to 000.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The process for producing aseptic packed cooked rice according to the present invention is shown in the chart of FIG.

Rice milled by a rice mill (polished rice) is stored in a rice storage. This rice is washed with degassed water by a conventional method and dipped, pretreated so as to have a water content of about 10 to 30%, and then quantitatively filled in a single-meal tray (container).

The tray, which is filled with a fixed amount of rice, is leveled, if necessary, and then fed into a closed chamber,
The container and rice are sterilized under high pressure and high temperature conditions. As a result, not only general live bacteria but also heat-resistant live bacteria can be killed.

The sterilization process in the closed chamber is 100
By using high-pressure pressurized steam at a temperature of not less than 0 ° C., preferably 130 to 140 ° C., it is possible to collectively perform a large number of trays contained in the closed chamber within a short time of several tens of seconds. Steam pressure is 2.7-3.0 kgf / cm
It is preferably about 2 and is pressed into the closed chamber from the steam generator.

By performing the sterilization treatment under such high-pressure and high-temperature conditions, the rice in each tray is promoted to be alpha, so that the subsequent rice cooking can be carried out smoothly in a short time.

It is particularly preferable that the sterilization treatment is performed by intermittently flushing high-pressure and high-temperature saturated steam with respect to the rice packed in the individual meal tray. For example, 5 to 1
The high-pressure high-temperature saturated steam flash treatment for 0 seconds is repeated 6 to 8 times as one cycle.

Such intermittent or intermittent autoclaving makes it possible to effectively carry out the sterilization without impairing the taste of rice, and at the same time, during non-interval without steam flush. In addition, the individual food tray can be advanced from the above-mentioned rice quantitative filling section toward the steam rice cooker, which enables efficient and speedy operation of the production line.

After sterilization in a closed chamber, each tray is cooked and filled with water in a fixed amount, and then put into a steam rice cooker to cook steam rice by a conventional method. Deaerated water is preferably used for cooking water in order to improve texture and yield. Also,
The water or hot water for cooking water has been sterilized in advance, and it is possible to use water adjusted to a predetermined pH value. When manufacturing packed products of mixed rice or red rice, in addition to filling the cooking water, the tray is filled with necessary seasoning liquid, coloring liquid, ingredients and the like.

In order to save space, it is preferable to use a multi-row, multi-stage gondola that is cyclically driven in the steam rice cooker. That is, a plurality of multi-stage gondola (for example, 8 shelves) capable of accommodating a plurality of (e.g., 8) trays are vertically stacked in parallel with each other in a plurality of (e.g. 8) stages at equal intervals. Based on this, a transport device is installed in which these multi-stage gondola are connected to a chain conveyor that is driven to circulate on a vertical plane at equal intervals. As the tray accommodating shelf plate, for example, openings for fitting the tray main body are formed in parallel for the number of accommodating trays, and the upper edge of the tray is placed around the openings. Therefore, a tray having a structure for accommodating a tray can be used.

When such a multi-row multi-stage gondola is used, the tray filled with sterilized rice and cooking water moves above the steam rice cooker (steam chamber) by the transfer device and returns. It is sent to each stage of the empty multi-stage gondola.
Then, the gondola containing the trays in all stages enters the steam chamber for a predetermined time (for example, about 3 minutes) while moving in the steam chamber.
Steam rice is cooked at 0 minutes.

It is possible to divide the steam chamber into a plurality of zones and independently control the temperature of each zone. As a result, the optimum steam temperature is set according to the rice cooking process.

The gondola which has completed the rice cooking is pulled up by the chain conveyor and the trays are sent out one by one onto the conveyor. The empty gondola returns toward the entrance of the steam rice cooker and is recycled to the next tray storage.

Each tray is checked for metal detection while being conveyed by the conveyor after completion of rice cooking, and defective products in which metal is detected are excluded from the line.

The tray that has passed the metal detection is then transferred to a hermetic sealing machine to seal the hermetic seal by applying an appropriate UV-sterilized lid material to the tray, and to cut unnecessary parts of the sealed lid material. Trimming is performed. Steam rice cooker airtight seal The trays between machines are transported by a conveyor, but in order to prevent secondary contamination due to exposure to the atmosphere for a short time during this period, a seal seal is provided from the outlet of the steam rice cooker. The machined area is installed in a clean booth with a cleanness of about 100 to 1000.

For example, a tunnel-shaped booth is provided between the outlet of the steam rice cooker and the hermetic sealer, and a clean air generator is attached to the upper center of the booth to continuously generate clean air. Maintaining a positive pressure in the booth (for example, 0.5 to 2 mmAq higher than the outside pressure), clean air is flowed from the top to the bottom of the booth, from the center to the outer periphery, and on the transfer conveyor, a hermetic sealing machine is used. Bacteria can be discharged to the outside by letting it flow toward the steam rice cooker.

The tray may be hermetically sealed after flushing with inert gas. If necessary, a deoxidizer can be enclosed.

After the tray is hermetically sealed, the tray is steamed for a predetermined period of time in order to make the difference in water absorption rate between the upper and lower layers of the cooked rice uniform and promote alpha. Inverting the hermetically sealed tray prior to the steaming process promotes equalization of the water level above and below. After steaming, the tray is passed through a cold water tank and cooled to room temperature. It is preferable to adopt a multi-stage multi-row gondola similar to the steam rice cooker described above for the steamer and the cooling tank to improve the processing efficiency.

After cooling, the inverted tray is returned to its original state,
The surface is dried, and after the post-processing steps such as printing the manufacturing date and expiration date, pinhole inspection, and weight inspection,
It is shipped in a predetermined case.

Aseptic packed cooked rice produced by the above method was subjected to an analytical test by the standard agar plate culture method. As a result, both the number of general bacteria (the number of viable bacteria) and the number of heat-resistant spores were 300 or less / g. It was confirmed to be substantially completely sterilized.

[0038]

EFFECTS OF THE INVENTION According to the present invention, the washed rice packed in the tray is sterilized under high pressure and high temperature conditions in a low moisture state before adding cooking water, so that not only general live bacteria but also Since the thermostable bacteria that may be attached to the rice can be completely killed, it is possible to provide a truly aseptic packed cooked rice.

In the present invention, in principle, encapsulation of an oxygen scavenger and pH adjustment, which were required for conventional complete sterilization, are unnecessary, and cost reduction can be realized.

Further, according to the present invention, unlike the case of the conventional retort treatment, a completely sterile packed cooked rice can be produced without impairing the taste.

[Brief description of the drawings]

FIG. 1 is a chart showing a process of producing a sterile packed rice according to the present invention.

Claims (6)

[Claims] 1. An individual food tray is filled with a quantity of rice soaked in washed rice, sterilized by high-pressure high-temperature saturated steam in a closed chamber, and at the same time, the rice is gelatinized, and then cooked water is poured to cook the rice. A method for producing aseptic packed cooked rice, which comprises applying a lid material to the above and hermetically sealing. 2. The method for producing aseptic packed cooked rice according to claim 1, wherein the sterilization treatment is performed by intermittently flushing high-pressure high-temperature saturated steam with respect to the rice filled in the individual meal tray. 3. The method for producing aseptic packed cooked rice according to claim 2, wherein high-pressure high-temperature saturated steam flash treatment for 5 to 10 seconds is repeated 6 to 8 times as one cycle. 4. The opening of the individual food tray is covered with a plate member having a substantially honeycomb shape in the sealed chamber, and the rice filled in the individual food tray is scattered by intermittent flash of high-pressure high-temperature saturated steam. The method for producing aseptic packed cooked rice according to claim 2, wherein 5. The method for producing aseptic packed cooked rice according to claim 1, wherein the cooked rice is cooked with a steam cooker. 6. The method for producing aseptic packed cooked rice according to claim 1, wherein the steps until the hermetic sealing is completed after the rice is cooked are performed in a clean booth.