JP2017018032A - Preservation method of unpolished rice, and unpolished rice preservation shed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain flavor of unpolished rice to the equivalent degree to new rice, even when a time has passed after harvesting.SOLUTION: A preservation method of unpolished rice has a constitution including a first step S1 of keeping the unpolished rice in a temperature range of -10°C or higher and 0°C or lower in a period of 10 days or longer and 90 days or shorter, and a second step S2 of keeping the unpolished rice to which the first step S1 is applied in a temperature range of 1°C or higher and 18°C or lower. By constituting the preservation method of unpolished rice in this way, change of the unpolished rice into rice of old crop, or proliferation of an insect or mold can be prevented, and sweetness of the unpolished rice is increased, and its flavor can be maintained equally to or higher than that of new rice.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for preserving brown rice, and a brown rice storage for preserving brown rice by the storage method.

  Brown rice harvested during the harvesting season may have a lower flavor and breed insects and molds compared to fresh rice due to the respiratory action and fat oxidation (old rice) after harvest. These are particularly prone to problems when brown rice is stored at temperatures above 15 ° C.

  In order to prevent brown rice from becoming old rice and the growth of insects and fungi, brown rice is often stored using, for example, the storage shown in Patent Documents 1 and 2. A plurality of bags storing brown rice are stored in a stack in the storage. By keeping the inside of this storage room at a low temperature of 12 to 14 ° C. and a humidity of 55 to 75%, the conversion of brown rice to old rice is delayed as much as possible, and the generation of insects and molds is prevented.

JP 2003-52 A JP 11-337243 A

  The storages shown in Patent Documents 1 and 2 simply delay the conversion of brown rice into old rice and prevent the propagation of insects and molds, so that there is a problem that the deterioration of the flavor with the passage of the storage period is inevitable. .

  Then, even if time passes since harvesting, this invention makes it a subject to maintain the flavor of brown rice at the same level as new rice.

  In order to solve the above problems, the present invention comprises a first step of holding brown rice in a temperature range of −10 ° C. to 0 ° C. for a period of 10 days to 90 days, and brown rice subjected to the first step. And a second step of maintaining the temperature in a temperature range of 1 ° C. or higher and 18 ° C. or lower.

  In the first step, the brown rice is stored at a so-called ice temperature in a temperature range that does not freeze, during which starch is decomposed and glucose is accumulated in the brown rice. This accumulation of glucose increases the free total sugar content and can improve the flavor by increasing the sweetness of rice.

  The temperature range of the first step is within the range of −10 ° C. or more and 0 ° C. or less as described above, but the preferable temperature range is −3 ° C. or more and 0 ° C. or less, and the more preferable temperature range is −1.5 ° C. or more and −0. .5 ° C. or lower. When this temperature is lower than −10 ° C., brown rice freezes and it is difficult for starch to decompose into glucose. On the other hand, when it is higher than 0 ° C., the effect of storage at ice temperature (degradation action of starch into glucose) Therefore, it is necessary to set the above temperature range.

  In addition, the retention period of the first step is within the range of 10 days or more and 90 days or less as described above, but the preferable retention period is 25 days or more and 45 days or less, and the more preferable retention period is 30 days or more and 40 days or less. . If this period is shorter than 10 days, the ice temperature storage is completed before the decomposition of starch into glucose is sufficiently completed. On the other hand, if it is longer than 90 days, the decomposition into glucose is sufficiently completed. Regardless, wasteful electric power is required to maintain the ice temperature, so the above holding period is required.

  The temperature range of the second step is in the range of 1 ° C. or higher and 18 ° C. or lower as described above, but the preferable temperature range is 5 ° C. or higher and 14 ° C. or lower, and the more preferable temperature range is 10 ° C. or higher and 14 ° C. or lower. . If this temperature is lower than 1 ° C, a large amount of electric power is required to maintain the temperature. On the other hand, if it is higher than 18 ° C, the respiration of brown rice becomes active and it becomes easy to progress to the conversion of old rice. It is necessary to. Note that the holding period of the second step is preferably a period until shipment.

  In this way, storing brown rice through the first and second steps prevents the brown rice from becoming old rice and prevents the growth of insects and molds, and increases the sweetness of the brown rice so that its flavor is equal to or higher than that of the new rice. Can be maintained.

  In the said structure, it is preferable that the free total sugar content contained in brown rice shall be 1050 mg / 100g or more by said 1st process. Thus, the flavor of brown rice can be further improved by increasing the free total sugar content.

  The brown rice preservation method described above can be applied to a brown rice storage. Thus, by applying to a storage, it can preserve | save the collective quantity (for example, 10 bags of 30kg brown rice storage bags collectively), and can improve preservation | save efficiency. The storage conditions (the temperature and period of the first step, the temperature of the second step) of the storage can be set, for example, by operating an operation panel provided on the front surface of the storage.

  The present invention includes a first step of holding brown rice in a temperature range of −10 ° C. to 0 ° C. for a period of 10 days to 90 days, and a temperature of 1 ° C. to 18 ° C. of the brown rice subjected to the first step. The second step of holding in the range, and a method for preserving brown rice was adopted. By configuring the storage method of brown rice in this way, it is possible to prevent brown rice from becoming old rice and to prevent the growth of insects and molds, increase the sweetness of brown rice, and maintain its flavor at or above that of new rice It becomes.

The figure which shows the processing flow of the preservation | save method of the brown rice of this invention The experimental results of Experiment 1 (using Koshihikari brown rice) are shown, (a) is the moisture content, (b) is the physical property (hardness), (c) is the physical property (stickiness), (d) is the free total sugar content, (E) Color tone (L value) The experimental results of Experiment 2 (using a simple brown rice) are shown, (a) is the moisture content, (b) is the physical property (hardness), (c) is the physical property (stickiness), (d) is the free total sugar content, (E) Color tone (L value), (f) Rice milling time The experimental results of Experiment 3 (using brown rice of Kinumusume) are shown, (a) is moisture content, (b) is physical properties (hardness), (c) is physical properties (stickiness), (d) is free total sugar content , (E) Color tone (L value), (f) Rice milling time

  An example of the processing flow of the brown rice preservation method of the present invention is shown in FIG. This storage method includes a first step and a second step.

  A 1st process (ice temperature storage) is performed for 35 days, for example in the temperature of -1 degreeC (refer S1 of FIG. 1). By exposing brown rice to a temperature of −1 ° C., the illusion that the brown rice is now winter is lost, and the starch in the brown rice is decomposed into glucose to store energy for overwintering, so as to prepare for germination. Thus, the starch in brown rice is decomposed | disassembled into glucose, sweetness improves and the flavor of brown rice can be improved. In addition, by keeping the temperature at an ice temperature of 0 ° C. or less, it is possible to suppress the propagation of insects and fungi.

  The temperature of the first step can be appropriately changed within a range of −10 ° C. or more and 0 ° C. or less. Moreover, a 1st process can be suitably changed within the period of 10 days or more and 90 days or less. In addition, although brown rice is normally stored in the state enclosed with the bag body whose capacity | capacitance is about 30 kg, the brown rice put in the room temperature state (for example, 25 degreeC) is used for the holding temperature (for example, -1 of 1st process). It usually takes about 5 days to lower the temperature uniformly to the center of the brown rice in the bag. For this reason, the period for actually maintaining the temperature in the first step is the number of days (about 5 days) required to lower the temperature from room temperature to the holding temperature in the first step in the above period (10 to 90 days). It is necessary to add the period. This number of days can be changed as appropriate in consideration of the cooling capacity of the storage for storing brown rice, the capacity and number of bags, the holding temperature, the room temperature, and the like.

  A 2nd process (low-temperature storage) is performed in the temperature of 12 degreeC, for example (refer S2 of FIG. 1). By exposing brown rice to a temperature of 12 ° C., it can be stored without causing deterioration in the quality of brown rice whose flavor has been improved by the first step (old rice). This second process is continued until the brown rice is shipped (see S3 in FIG. 1).

  This method for preserving brown rice is applied to the temperature control of the brown rice storage. This storage is preferably configured to set the temperature and period of the first step and the temperature of the second step, for example, by operating an operation panel provided on the front surface of the storage.

  Various characteristics of the brown rice preserved by the brown rice preservation method according to the present invention were evaluated. In this experiment, three types of brown rice were used: (1) Koshihikari, (2) Hitomebore, and (3) Kinusume. All brown rice was harvested in 2014 in Tottori Prefecture. Stored at 12 ° C. for 35 days at a temperature of −1 ° C. (Example (see FIG. 1)), not stored at low temperature (stored at room temperature) (Comparative Example 1), Three levels, one stored for 35 days in temperature (Comparative Example 2), were prepared for each brown rice.

  Each brown rice of the above (1) to (3) was crushed and dried, and the water content was measured from the change in weight before and after drying. In addition, after cooking each brown rice, this rice cooked rice is filled in a predetermined container, and the bottom of the cone-shaped plunger attached to the rheometer (RT-3002D, manufactured by Rheotech Co.) is pressed against the cooked rice in the container. The cooked rice was compressed, and the physical properties (hardness, stickiness) of the cooked rice were measured. Moreover, the free total sugar in each brown rice was extracted with ethanol, and the free total sugar content was measured by the phenol-sulfuric acid method. Furthermore, the color tone (L value) of cooked rice was measured using a color difference meter (SZ-Σ80, manufactured by Nippon Denshoku Industries Co., Ltd.). About each brown rice of said (2) and (3), it polished with the latest type | mold household rice milling machine, and measured the rice polishing time until the completion of the rice polishing.

  FIG. 2 shows the evaluation results of (1) Koshihikari, FIG. 3 shows the evaluation results of the above (2) eye drop, and FIG. 4 shows the evaluation results of (3) swells.

  In the brown rice of Koshihikari (see FIG. 2), the water content of the example was about 1.0 to 1.4 points higher than that in Comparative Example 1 and Comparative Example 2 (see (a) in this figure). Although physical properties (hardness, stickiness) were slightly improved, no significant difference was found between Comparative Example 1 and Comparative Example 2 and the examples (this figure (b) and (c)). reference). The free total sugar content was confirmed to be about 70 mg / 100 g higher in Examples than in Comparative Examples 1 and 2 (see FIG. 4D). Although the color tone (L value) was slightly higher in Example than in Comparative Example 2, no significant difference was observed (see FIG. 4E).

  In the brown rice of the first time (refer FIG. 3), compared with the comparative example 1 and the comparative example 2, the moisture content of the Example became about 0.8-0.9 point higher (refer this figure (a)). The physical properties (hardness and stickiness) were not significantly different between Comparative Example 1 and Comparative Example 2 and the Examples (see FIGS. (B) and (c)). It was confirmed that the free total sugar content was higher by about 50 to 120 mg / 100 g in the example than in Comparative Example 1 and Comparative Example 2 (see FIG. 4D). Although the color tone (L value) was slightly higher in Example than in Comparative Example 2, no significant difference was observed (see FIG. 4E). The rice milling time in the example was 1 minute shorter than that in Comparative Example 2 (see Fig. (F)).

  In the brown rice of Kinusume (see FIG. 4), the water content of the example was increased by about 0.5 to 0.9 points as compared with Comparative Example 1 and Comparative Example 2 (see FIG. 4A). . The physical properties (hardness and stickiness) were not significantly different between Comparative Example 1 and Comparative Example 2 and the Examples (see FIGS. (B) and (c)). It was confirmed that the free total sugar content was higher by 60 to 100 mg / 100 g in Examples than in Comparative Examples 1 and 2 (see FIG. 4D). As for the color tone (L value), no great difference was found between the example and the comparative example 2 (see FIG. 4E). The rice milling time was 45 seconds shorter in the example than in the comparative example 2 (see Fig. (F)).

  From the evaluation results shown in FIG. 2 to FIG. 4, when judged comprehensively over all types of brown rice, the water content and free total sugar content are higher in the example than in Comparative Example 1 and Comparative Example 2. There was a tendency for rice milling time to shorten as it increased. From this, the first step in the method for preserving brown rice according to the present invention is to improve the texture of cooked rice with an increase in water content, and to increase the free total sugar content to 1050 mg / 100 g or more. It can be said that it has the effect | action which aims at the improvement of the flavor by sweetness. In addition, brown rice generates heat due to friction between brown rice during milling, but it has become possible to shorten the time for milling, so reducing the heat generated by brown rice and preventing the quality deterioration of brown rice due to heat generation as much as possible. Can do. On the other hand, physical properties (hardness, stickiness) and color tone (L value) were not significantly different, and it was confirmed that the texture and appearance similar to those of new rice were ensured.

  The above is merely an example showing the storage method of brown rice according to the present invention, as long as it can solve the problem of the present invention that the flavor of brown rice is maintained at the same level as fresh rice even if time has passed since harvesting. However, it is permitted to change a part of the processing flow of the storage method and to change the temperature and holding time of each process.

S1 first step (ice temperature storage)
S2 Second step (low temperature storage)

Claims (3)

A first step (S1) for holding brown rice in a temperature range of −10 ° C. to 0 ° C. for a period of 10 days to 90 days;
A second step (S2) for holding the brown rice subjected to the first step in a temperature range of 1 ° C or higher and 18 ° C or lower;
Storage method of brown rice including.   The method for preserving brown rice according to claim 1, wherein a free total sugar content contained in the brown rice is 1050 mg / 100 g or more by the first step (S1).   The brown rice preservation | save which performs cooling control in a warehouse by the preservation | save method of brown rice of Claim 1 or 2.

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