JPS5930386B2 - Method for producing cooked rice food - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cooked rice foods such as rice ball packs and commercially available lunch boxes.

Rice food is easily perishable and is considered to be a food with a high risk of causing food poisoning.

Therefore, in order to kill or prevent the proliferation of microorganisms that cause spoilage, rice foods have traditionally been processed by adding additives such as vinegar, acetic acid derivatives, phosphates, and glycine, or irradiated with ultrasonic waves after product packaging. Heat sterilization was also performed.

However, these methods do not impair the taste of rice foods,
Moreover, it was insufficient to suppress the proliferation of microorganisms.

In other words, when lowering the pH value of cooked rice by adding vinegar or the like, the upper limit is 4.9 to 4.7, considering the taste; lowering it below that level will result in undesirable tastes such as strong sourness. Become.

On the other hand, in boiled rice foods with a pH of about 4.9 to 4.7,
After processing and packaging or packaging into rice balls, bento boxes, etc.1
Even if heat sterilization is performed at a temperature of about 00°C, the spores will not die, so the remaining spore-forming bacteria will germinate and multiply during transportation and storage.

As a result, it could only be stored for 2 to 3 days in an environment of about 30°C.

Therefore, the present invention was made with the object of providing a method for producing a cooked rice food that has good taste and storage stability.

The configuration and embodiments of the present invention will be described below.

The method for producing a cooked rice food according to the present invention includes adding gluconic acid or its cyclized intramolecular ester compound before cooking the rice, in which raw rice is cooked, molded and packaged or packed in containers, and then sterilized. , is characterized in that the pH value of the cooked rice after cooking is 3.5 to 4.0.

The reason for using gluconic acid or its cyclized intramolecular ester compound as a preservative is that gluconic acid is a substance with very weak acidity among organic acids, and it lowers the pH value of cooked rice by 4 without making it taste sour. This is because it can be set to .0 or less.

Germination of bacterial spores is inhibited under such a high hydrogen ion concentration of pH 4.0 or lower.

Glucono-δ-lactone (hereinafter referred to as GDL) is generally used as the cyclized intramolecular ester compound of gluconic acid.

In this case, whether gluconic acid or GDL is used, an acid-lactone equilibrium value will eventually be reached over time.

Any method may be used to sterilize the raw rice after it has been cooked and molded and packaged or packed in containers, but usually the cooked rice is irradiated with microwaves and its thermal effect is used to control the temperature of the cooked rice. A method is used in which heat sterilization is carried out by raising the temperature to 70 to 90°C.

This sterilization treatment almost completely kills bacterial propagules.

Next, one embodiment of the present invention will be described.

First, immediately before cooking rice, GDL is added at a ratio of 55g to 8kg of raw rice, and then the rice is cooked.

As a result, there is almost no sourness, and the pH is 3.
, I was able to get 7 servings of rice.

Then, separately prepared quickly, for example, salted salmon flakes (salmon flakes with a salinity of 15%, GDL added and stirred, vacuum packed and sterilized by boiling for 30 minutes, pH value is 40.2) is added to the cooked rice. After wrapping the rice ball in a synthetic resin film, the temperature of the cooked rice is raised to 70 to 90°C using a microwave and heated for 10 minutes.

Thereafter, the product is vacuum cooled until the product temperature reaches 25°C.

Regarding the rice balls obtained in this way, it is
After being stored in a constant temperature container at ℃ for 3 days and 5 days, the taste, odor, and number of viable bacteria were examined.

For comparison, rice balls (control (I)) were prepared in the same manner as in the above example except that vinegar was added to make the rice OpH value after cooking 4.7, and rice balls were prepared in the same manner as in the above example until packaging. A test was also conducted in the same manner as in the example, but on rice balls that were not subjected to heat sterilization treatment (control @).

The results are shown in Table-1. As shown in the table above, the control (I
) and 0 were both defective on the 3rd day, but the rice balls according to the examples of the present invention were normal on the 3rd day, and 5.
Even after storage for several days, the cooked rice was only slightly aged.

Next, a simple sensory test regarding sourness was conducted on cooked rice (pH 3, 7) after cooking without adding oysters in the above example.

The number of panelists was 20, and for comparison, the pH value of cooked rice after cooking was adjusted to 4.7 by adding vinegar (vs. J'!! [)), and the pH value was set to 4.4. A sensory test was also conducted on the sample (control ■) using the same method.

The results are shown in Table-2.

As is clear from the above table, the cooked rice according to the examples of the present invention hardly tastes sour.

According to the method of producing cooked rice food as in this invention, most of the living cells are killed by the sterilization treatment, and the remaining spores are difficult to germinate because the pH value of the medium is extremely low.
Bacterial growth is suppressed.

As a result, the cooked rice food produced by the method according to the present invention was able to maintain its quality for 3 to 5 days under storage conditions of 25 to 30°C, and its shelf life was significantly improved.

Moreover, since the product has almost no sour taste, a cooked rice food that is satisfying in terms of taste can be obtained.

Claims (1)

[Scope of Claims] 1. In a method for producing cooked rice food in which raw rice is cooked, molded and packaged or packed in containers, and then sterilized, gluconic acid or its cyclized intramolecular ester compound is added before rice cooking, and gluconic acid or its cyclized intramolecular ester compound is added to A method for producing a cooked rice food, which comprises adjusting the pH value of the cooked rice to 3.5 to 4.0. 2. The method for producing a cooked rice food according to claim 1, wherein the cyclized intramolecular ester compound is glucono-δ-lactone. 3. The method for producing a cooked rice food according to claim 1 or 2, wherein the sterilization treatment is a heat sterilization treatment in which the cooked rice is irradiated with microwaves to raise the temperature of the cooked rice to 70 to 90°C.