JPH0563132B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing retort-packed white rice. [Prior Art and Problems] Conventionally, retort-packed white rice has been produced by washing raw rice, soaking it in water for a desired period of time, steaming it, filling it into a packaging bag, and sterilizing it by heat and pressure.
In the heat sterilization mentioned above, based on the provisions of the Food Sanitation Law, it is a standard for sterilization in the sense of killing Bacteria botulinum.
Although sterilization is carried out under the condition of F _p =4 or more, in actuality heat sterilization is carried out so that F _p =4.5 to 5.0 in consideration of safety. However, when sterilization is carried out under such conditions, browning of rice grains is accelerated due to the Maillard reaction, resulting in a significant loss of quality. On the other hand, there is known a method for producing portable cooked rice (Japanese Patent Publication No. 17581/1981), which has already been filed and patented by the present applicant. In this method, raw rice is washed to suppress the excess starch that flows out when rice grains are steamed and to eliminate stickiness.
It is a method of immersing in the aqueous solution of 5 for 30 to 120 minutes,
It is not intended to prevent browning. The present invention was made to solve the above-mentioned conventional problems, and provides a method for producing high-quality retort-packed white rice that does not brown even when the pressure and heat sterilization is increased to a range of F _p = 4.5 to 5.0. That is. [Means for Solving the Problems] The present invention provides a method for washing raw rice, immersing it in water for a desired period of time, further steaming it, filling it into a packaging bag, and sterilizing it by pressure and heating. immersed in an aqueous solution whose pH has been adjusted with an organic acid and filled into the packaging bag;
This is a method for producing retort-packed white rice, which is characterized by adjusting the pH of the rice itself after heat sterilization to be 5.8 to 6.2. Examples of the organic acid used as a pH adjuster for the aqueous solution include citric acid and lactic acid. The aqueous solution is filled into a packaging bag and adjusted to be more acidic than the pH of the rice itself, which is 5.8 to 6.2, after being heat sterilized. The reason why we limited the pH of the rice itself after filling it in the packaging bag and heating and sterilizing it is that while setting the pH to less than 5.8 is effective in preventing browning, the surface of the rice grains becomes dull and the product value decreases. This is because if the pH exceeds 6.2, the browning prevention effect cannot be exhibited. The pressurization during sterilization is performed to prevent the contents of the packaging bag from expanding due to heating and crushing the bag. Such pressurized heating is 1.0Kg/cm ²
It is desirable to carry out at a temperature of 100 to 118°C. [Function] According to the present invention, rice after steaming is immersed in an aqueous solution whose pH has been adjusted with an organic acid and filled into a packaging bag, and the pH of the rice itself after heat sterilization is adjusted to 5.8 to 6.2. In particular, it is possible to obtain high-quality retort-packed white rice without browning even if the pressure and heat sterilization is increased to a range of F _p =4.5 to 5.0. In addition, by immersing the rice after steaming in an aqueous solution whose pH has been adjusted with an organic acid, the organic acid penetrates into the rice grains well, and the pH of the rice itself after being filled into a packaging bag and heat sterilized is maintained.
5.8 to 6.2, it is possible to shorten the processing time for the purpose of pH adjustment. [Examples] Examples of the present invention will be described in detail below. Example 1 First, 500 g of rice was washed twice (2.5 minutes) in a washing container with water overflowing.
After draining the water, it was soaked in water for 2 hours. Continuing,
After thoroughly draining the water, it was stored in a steamer lined with bleaching cloth, and after being leveled, it was steamed for about 15 minutes. Immediately after steaming, it was immersed for several seconds in a PH-adjusted aqueous solution (PH-adjusting immersion liquid) having the following composition, and then taken out. The pH of the rice itself at this time was 5.75. (Composition of soaking solution for pH adjustment; PH=3.68) Water 2000g Salt 20g Glycine 5g Citric acid 1.6g Next, the rice was taken out from the soaking solution for pH adjustment.
After putting 200g into a packaging bag made of a three-layer laminate film of stretched propylene/vinylidene chloride/unstretched polypropylene and degassing it, it was packed at 1.5Kg/cm ² .
Retort packaged white rice was produced by pressurizing and heating sterilizing at 116°C for 25 minutes. The pH of the white rice itself after pressure and heat sterilization was 6.20. Example 2 Retort-packed white rice was produced in the same manner as in Example 1 except that a dipping liquid for pH adjustment having the following composition was used. The PH of the rice itself taken out after being treated with the soaking liquid was 5.30, and the PH of the white rice itself after pressure and heat sterilization was 5.89. (Composition of soaking liquid for pH adjustment; PH=3.32) Water 2000g Salt 20g Glycine 5g Citric acid 3g Comparative example Retort packaging in the same manner as in Example 1 except that the rice after steaming was not treated with the pH adjustment soaking liquid. I made white rice. In addition, the pH of the white rice itself after pressure and heat sterilization was 6.79. Reference Example Retort-packed white rice was produced in the same manner as in Example 1 except that a dipping liquid for pH adjustment having the following composition was used. The PH of the rice itself taken out after being treated with the soaking liquid was 5.21, and the PH of the white rice itself after pressure and heat sterilization was 5.69. (Composition of dipping liquid for pH adjustment; PH = 2.81) Water 2000g Salt 20g Glycine 5g Citric acid 4g The obtained retort-packed white rice of Examples 1 and 2, Comparative Example, and Reference Example are all indicative of sterilization.
F _p was 4.5 to 5.0. In addition, the browning state of each retort-packed white rice was measured and determined using a color difference meter (trade name: Σ-80, Z-OPTICAL SENSOR, manufactured by Nippon Denshoku Kogyo Co., Ltd.). In addition, a sensory evaluation was conducted by a panel. The results are shown in Table 1 below. In the color difference evaluation, if L ^* is 80 or more, a ^* is -1.7 or less, and b ^* is 7.5 or less, it is determined that there is no browning.

[Table] From the results in Table 1 above, the PH of the rice itself after being immersed in an aqueous solution whose PH was adjusted with organic acid (citric acid) and filled into a packaging bag after being heat sterilized was
It can be seen that in Examples 1 and 2, which were adjusted to F _p = 5.8 to 6.2, high quality retort-packed white rice without browning could be obtained even if the pressure and heat sterilization was increased to a range of F p =4.5 to 5.0. On the other hand, in the comparative example, which is a conventional method in which the rice itself has a neutral pH of 5.8 to 6.2, browning occurs when pressure and heat sterilization is performed in the range of F _p =4.5 to 5.0. Also, the pH of the rice itself is 5.8 to 6.2.
In the reference examples on the acidic side, browning does not occur even if pressure and heat sterilization is performed in the range of F _p =4.5 to 5.0, but the luster and transparency are lost and the commercial value decreases. [Effect of the invention] As detailed above, according to the present invention, F _p =4.5~
It is possible to provide a method for producing high-quality retort-packed white rice that does not brown even when subjected to pressure heat sterilization up to a temperature of 5.0 by a simple process.

Claims (1)

[Claims] 1. When raw rice is washed, immersed in water for a desired period of time, further steamed, and then packed into a packaging bag and sterilized by pressure and heat, the steamed rice is immersed in an aqueous solution whose pH has been adjusted with an organic acid. A method for producing retort-packed white rice, which comprises adjusting the pH of the rice itself to be 5.8 to 6.2 after being filled into the packaging bag and sterilized by pressure and heat.