JP6223711B2 - How to absorb rice - Google Patents

Description

  The present invention relates to a method for absorbing rice.

  When cooking rice, it is common to provide an immersion process as a process before starting rice cooking. The dipping process is a process of adjusting the water content of rice by immersing the rice in water. From the viewpoint of rice cooking efficiency, it is preferable that the time required for the dipping process is as short as possible. However, if the time is short, the rice becomes hard rice with a core remaining in the rice due to a low water content. Also, if the time is long, it becomes sticky rice due to its high water content. Therefore, the immersion time is at least 30 minutes or more, and usually 1-2 hours are preferable.

  As a method for shortening the time required for the dipping process, for example, in Patent Document 1 (Japanese Patent Application Laid-Open No. Hei 8-252070), the deaerated water is washed within 5 minutes, and then the deaerated water is hydrated. Later, a method of starting heating, preferably within 10 minutes, is disclosed. In this method, the deaerated water permeates while taking in the air in the rice grains, so that it is considered that the water permeates faster and more uniformly than when normal water is used.

Patent Document 2 (Japanese Patent Laid-Open No. 7-327617) discloses a method of performing preliminary cooking before immersion. In this method, the washed rice is retained for about 10 minutes in a storage chamber into which steam having a steam pressure of about 3 kgf / cm ² is fed. When rice and water are heated, a part of the micelle structure composed of rice starch particles breaks down to form a gap. It is believed that water molecules enter this gap and the rice expands, increasing the water absorption rate in the dipping process. According to this method, when 80 ° C. hot water is used, the immersion time is reduced to about 15 minutes.

  In Patent Document 3 (Japanese Patent Laid-Open No. 2008-220327), rice and water are rapidly heated by microwave irradiation in a chamber maintained at a pressure higher than atmospheric pressure, and then the pressure in the chamber is gradually increased. Discloses a rice cooking method in which immersion and washing rice are performed in one step by providing a step of reducing the pressure.

  Further, pre-washed soaked rice that can be cooked immediately by adding water without adding pre-treatment such as soaking of washed rice is known. This washed soaked rice is rice obtained by pre-treatment such as pregelatinization, washed rice and soaking. For example, Patent Document 4 (Japanese Patent Application Laid-Open No. 7-177854) discloses a method of producing pre-washed soaked rice by performing pre-cooking before soaking and then secondary cooking.

  In Patent Document 5 (Japanese Patent Application Laid-Open No. 2002-17276), the rice is soaked in high-temperature water until the entire portion from the surface layer to the center of the rice has a high water content, and then slowly dried for a long time. A method for producing washed rice soaked is disclosed. Patent Document 6 (Japanese Patent Application Laid-Open No. 2007-1111044) includes a step of humidifying non-washed rice with a mild humidification rate, and a method of producing washed rinsed rice by drying the humidified rice with a mild reduction rate. It is disclosed. Patent Document 7 (Japanese Patent Application Laid-Open No. 2010-239927) discloses that brown rice cooked under a pressure of 1 to 5 atm is frozen and then thawed, dried to a moisture content of 20% or less, and then washed and washed. A method for producing rice is disclosed. In Patent Document 8 (Japanese Patent Laid-Open No. 2012-161252) and Patent Document 9 (Japanese Patent Laid-Open No. 2013-51889), pressure steaming was performed for 60 to 180 seconds under a pressure of 0.05 MPa to 0.3 MPa. A method for producing pregelatinized rice by making the rice into a single grain and further cooking rice is described. In this method, it is considered that the water absorption capacity is enhanced by subjecting the surface layer to α by steaming under pressure and making the central part porous.

  By the way, in Patent Document 10 (Japanese Patent Laid-Open No. 2001-169915), Patent Document 11 (Japanese Patent Laid-Open No. 2006-149223), and Patent Document 12 (Japanese Utility Model Registration Publication No. 3142166), there is a continuous rice cooking method. It is disclosed. Each of the rice cookers is provided with a first conveyor means provided in the first steam chamber, a second conveyor means provided in the second steam chamber provided immediately below, and further provided immediately below the first conveyor means. Third conveyor means provided in the three steam chambers, primary steaming means for performing primary steaming in the first steam chamber, and secondary steaming for performing secondary steaming in the second steam chamber. Means and watering means for spraying water between the primary steaming and the secondary steaming. In these rice cookers, rice grains are heated by saturated steam at about 140 ° C. and about 0.36 MPa in the first steam chamber and by superheated steam at about 150 ° C. and about 0.48 MPa in the second steam chamber, respectively. In each steam chamber, hot water of about 60 to 90 ° C. is sprinkled for hydration. In addition, tertiary steaming may be performed in the third steam chamber.

  Moreover, in nonpatent literature 1, in the continuous-type rice cooking method as described in patent documents 10-12, if it adjusts and the amount of water sprays, it will not become hard after storage and the degree of gelatinization will be kept high. , It has been reported that delicious rice can be obtained compared to rice cooked with a rice cooker for general households

JP-A-8-252070 JP-A-7-327617 JP 2008-220327 A JP 7-177854 A JP 2002-17276 A JP 2007-111044 A JP 2010-239927 A JP 2012-161252 A JP 2013-51889 A JP 2001-169915 A JP 2006-149223 A Registered Utility Model No. 3142166

Proceedings of the 59th Annual Meeting of the Japan Society for Food Science and Technology Issued in August 2012, p204

  By the way, the method disclosed in Patent Document 1 preferably requires deaerated water having a dissolved oxygen concentration of 0.1 ppm or less. Therefore, if the deaeration is insufficient, the water content of the rice is reduced, and there is a risk that the rice has a core remaining in the rice. In the method disclosed in Patent Document 2, although the immersion time is shortened, the immersion time of 10 minutes or more is required, and it cannot be said that the immersion time is sufficiently shortened. The method disclosed in Patent Document 3 not only requires pressure and pressure reduction operation, but also requires a sealed chamber, which cannot be said to be a simple method.

  In addition, the method disclosed in Patent Document 4 is a method having a step of immersing in immersion water after primary cooking with steam at 100 ° C., and shortening the immersion time by primary cooking. However, the immersion time in this method is 20 minutes, and it cannot be said that the time has been sufficiently shortened. The method disclosed in Patent Document 5 is a method of slowly drying after impregnating water to the center of the rice by washing with hot water of 60 to 80 ° C. This method also requires about 20 minutes of work time. In the method disclosed in Patent Document 6, the inside of the rice grain is made porous. However, it takes about 24 hours for the humidification time, and cannot be said to be a rapid method. The method disclosed in Patent Document 7 not only targets low amylose rice, but also requires pressurization of 1 to 5 atmospheres. And the method described in patent document 8 and patent document 9 can perform an immersion process in a very short time of about 60 to 180 seconds. However, since pressurization of about 0.05 to 0.3 MPa is required, the apparatus becomes large.

  On the other hand, it is described in Patent Document 11 that rice can be cooked by using washed rice, and the apparatus of Patent Documents 10 to 12 can cook washed rice without going through an immersion process. However, in the methods described in these patent documents, rice is cooked with saturated steam in the first steaming process, and steamed with superheated steam in the second steaming process, but the rice cooking mechanism is unknown. It was.

  Under such circumstances, the inventors of the present application have been studying the rice cooking mechanism in the rice cooking method disclosed in Patent Documents 10 to 12, and found that the rice can be absorbed in a very short time. It came to complete.

  That is, an object of the present invention is to provide a method for causing rice to absorb water in a very short time.

  The water-absorbing method for rice according to the present invention is characterized in that non-immersed raw rice is placed in a superheated steam atmosphere while sprinkling water.

  According to the present invention, the time required for the water absorption step is greatly reduced, and an effect equivalent to the soaking that can be performed in a very short time of about 1 to 3 minutes can be obtained.

  In the present invention, non-immersed raw rice is rice that requires an immersion step before cooking. Non-immersed raw rice is different from rice that has been cooked once, such as pregelatinized rice, or washed-immersed rice as disclosed in Patent Documents 1 to 3. As long as it is non-immersed rice, either brown rice or polished rice may be used. Moreover, it does not ask | require whether the raw material rice used by this invention is the rice which does not require washing | cleaning before cooking rice called what is called non-washing rice. In addition, in the present invention, fast-cooked rice means rice that can be immediately subjected to the rice cooking process without being immersed, after washing or without washing, and is distinguished from pregelatinized rice.

  In the present invention, superheated steam is different from saturated steam, and means steam that has been superheated to a temperature of saturated steam (100 ° C. at atmospheric pressure) or higher. Superheated steam is obtained by various superheaters. Superheaters are publicly known, and the heating method is not limited. The temperature of superheated steam should just be 100 degreeC or more, Preferably it is 110 degreeC or more. On the other hand, if the temperature of the superheated steam is too high, the drying of the rice grains tends to proceed, approaching a state of drying or steaming rather than water absorption, and is not preferable. Therefore, the upper limit is preferably 200 ° C., more desirably 150 ° C.

  Unimmersed raw rice is placed in a superheated steam atmosphere. In this specification, to put it in a superheated steam atmosphere means that superheated steam is applied to non-immersed raw rice in a state open to the atmosphere. In other words, it means putting raw rice in a state where it is rapidly heated by superheated steam having large thermal energy. Examples of the method for placing in the superheated steam atmosphere include, for example, a batch-type method in which raw rice is placed in an unsealed steam chamber and superheated steam is supplied into the steam chamber, or a belt conveyor disposed in an unsealed steam chamber. There is a continuous method for supplying superheated steam into the steam chamber while continuously feeding the raw rice through such a conveyance path.

  In this invention, watering is performed to the raw material rice put in the superheated steam atmosphere. In the water absorption method according to the present invention, it is not sufficient to rapidly heat the raw rice with superheated steam, and it is necessary to supply water to the heated raw rice. An appropriate water absorption rate (generally, 20-30% of the mass of rice grains is a standard for cooking in a pot) is necessary for good cooking, but superheated steam This is because the amount of water in the inside cannot cover this amount of water absorption.

  The temperature of the water to be sprinkled is 30 to 90 ° C, preferably 50 to 90 ° C, desirably 70 to 90 ° C. When the temperature is low, the water in the superheated steam is cooled by the water spray, and as a result, it may condense on the surface of the rice grains and the water may not sufficiently penetrate into the rice grains.

  The amount of water spray is appropriately adjusted so that the water absorption rate of rice is about 25 to 40%. The sprinkling amount varies depending on the treatment time, the temperature of the superheated steam, and the amount of raw rice, but the standard is approximately 1.0 to 2.0 L per minute. While in the superheated steam atmosphere, water may be sprinkled with an equal watering amount or intermittently. Moreover, in order to adjust the water absorption rate of rice, after stopping watering, it can be placed in a superheated steam atmosphere for a short time.

  The water absorption principle of rice in the method according to the present invention is considered as follows. First, when superheated steam having large heat energy enters the voids of the rice grains, it condenses in the voids and becomes water. At the same time, the inside of the gap is evacuated, and it is considered that water, which is a liquid supplied by watering, penetrates instantaneously. This phenomenon is about 10 seconds to 1 minute in time, and this effect is considered to correspond to an immersion effect of 20 minutes or more. At this time, if the saturated water vapor is about 100 ° C., condensation occurs on the surface of the rice and the surface of the rice grains is just wetted. In addition, even if it is saturated steam at about 150 ° C., the steam has little thermal energy, so even if condensation occurs inside the rice grain, the inside of the gap does not become a vacuum, and a sufficient amount of water does not enter the gap Conceivable.

  The time for placing in the superheated steam atmosphere is 5 minutes at the longest, and the time for spraying is 3 minutes, and 5 minutes at the most is sufficient. When the watering time exceeds 5 minutes, the surface of the rice becomes sticky and tends to become alpha. On the other hand, although the phenomenon that water permeates into the grains of rice instantaneously is used, it is desirable to spray water in a superheated steam atmosphere preferably for 1 minute or longer because sufficient water absorption cannot be performed when the water spray time is short. .

  The rice after water absorption absorbs 25 to 40% of water, which is said to be able to cook delicious rice, with respect to the mass of the raw rice, and can be handled in the same manner as the soaked soaked rice for 20 minutes or more as described above. That is, the rice obtained by the above method is used as quick-cooked rice that can be cooked immediately without being immersed in water. The rice cooking method may be a rice cooking method by pot-making or a continuous rice cooking method using steaming. Known methods are also applied to the cooking method by cooking in a pot and the continuous cooking method by steaming. For example, according to the continuous rice cooking method, the primary steaming by saturated steam and the primary steaming are performed while sprinkling warm water while transferring the water-absorbing rice obtained by applying the method of the present invention. Rice is cooked by secondary steaming with superheated steam while being transferred. According to this method, a so-called dipping step can be omitted, and rice can be cooked continuously from non-immersed raw rice.

  Since the rice absorbed by the water absorption method of the present invention is placed in a superheated steam atmosphere of 100 ° C. or higher, so-called miscellaneous germs are reduced and storage stability is improved. Therefore, if the obtained rice is packaged in a clean environment, quick-cooked rice that can be stored for a long time without undergoing a drying process is provided.

  Next, the present invention will be described in more detail based on the following examples. In addition, it cannot be overemphasized that the technical scope of this invention is not limited to the following Example.

(Water absorption test)
A water absorption test was performed using commercially available non-washed rice (Koshihikari produced in Shiga Prefecture). For the water absorption test, a water absorption chamber provided with superheated steam or saturated water vapor, a belt conveyor for transferring unimmersed raw rice, and a water absorption nozzle equipped with a water spray nozzle for sprinkling water from above the raw rice transferred in the water absorption chamber A device was used. The belt conveyor also has a function of carrying raw rice into the water absorption chamber and carrying out the rice absorbed in the water absorption chamber to the outside of the water absorption chamber.

  The water absorption time was adjusted by changing the conveying speed of the belt conveyor (time to pass through the water absorption chamber), and was 3 minutes and 1.5 minutes. The temperature of water sprayed was 80 ° C., and the amount of water sprayed from the water nozzle was adjusted to the range of 1.0 to 2.0 L / min so that the water absorption amount (water absorption rate) with respect to the raw rice was about 25 to 40%. . The temperature of saturated steam (normal pressure) was 100 ° C., and the temperature of superheated steam (normal pressure) was 120 ° C. or 127 ° C. The obtained water-absorbing rice was evaluated by visual observation and touch.

  As a result, when water was sprayed for about 1.5 to 3 minutes in a superheated steam atmosphere at 120 to 127 ° C., the whole became uniformly white turbid rice grains, and water-absorbed rice in a state close to water absorption was obtained. In addition, when the raw rice was soaked in 1.4 times the amount of water for 1 hour and then drained, the same level of transparency as that of the reference rice was obtained. It was easy to collapse. In addition, even if it sprinkled for about 10 minutes in 100 degreeC saturated water vapor atmosphere, it was the feeling that the surface of the rice grain was alpha-ized, and it was not what the rice grain absorbed.

(Preservation test)
A preservation test was conducted on the rice after water absorption. The water-absorbed rice was placed in a sterilized sealed container in a clean room and stored at 20 ° C. for 5 days. One day, two days, and five days after the start of storage, a general bacterial test was performed on each rice. The above reference rice was used as a control and stored in the same manner. In order to prevent drying in the sealed container, a container containing saturated saline was placed in the sealed container.

As a result, in the control, 10 ² / g or more of bacteria were detected from the day of storage start, and 10 ⁷ / g or more of bacteria were detected on the first day of storage. On the other hand, in the cooked rice, bacteria were not detected even on the 5th day from the start of storage, and the sterility was maintained. Further, there was no yellowing or off-flavor even after 5 days.

(Cooking rice test)
Rice was cooked using the rice after water absorption. For cooking rice, use an IHI rice cooker for household use (SR-SU105, manufactured by Panasonic Co., Ltd.) with an appropriate amount of rice and water (adjusted amount of absorbed water so that the amount of water is 1.4 times that of raw rice). Put in and cook in fast cooking mode (time required 25 minutes). Moreover, the rice after water absorption was continuously cooked by the 1st steaming process using saturated steam of 100 degreeC, and the 2nd steaming process using 120 degreeC superheated steam. Any rice could be cooked without problems. Moreover, regarding the flavor, it was indistinguishable from cooked rice cooked with standard rice using the rice cooker.

  According to the present invention, rice can be absorbed in a short time, and quick-cooked rice that does not require soaking before cooking is produced in a short time.

Claims (4)

A method of absorbing rice, comprising a step of applying superheated steam for 1 to 5 minutes in an unsealed state while sprinkling water at 30 to 90 ° C. in non-immersed raw rice. A method for producing quick-cooked rice that can be cooked without being soaked in water,
A method for producing water, comprising sprinkling water at 30 to 90 ° C. into non-immersed raw rice and applying water to superheated steam for 1 to 5 minutes in an unsealed state . A continuous cooked rice production method comprising the steps of claim 1 and a step of cooking rice by a subsequent steaming step. Rice after water obtained in the process according to claim 1, or a fast cook rice obtained by the method of claim 2, the step of the rice by adding water kettle cooking or continuous steaming step A method for producing cooked rice, comprising: