【発明の詳細な説明】[Detailed description of the invention]
本発明は水つぽさがなく生煮えの状態もない均
一な食感を有する常温で長期保存が可能な調理済
米飯レトルト食品の製造法に関するもので、特
に、洗米後、含水させた米を水切りし、あらかじ
め加熱した後、さらにこの処理米を適切な量の水
と共に密閉可能な容器に充填し、反転吸水させた
後、レトルト調理殺菌する事を特徴とする米飯レ
トルト食品の製造法に関するものである。
従来、米飯レトルト食品は、洗米後直ちに通常
の炊飯方式で炊き上げ、炊き上げられた米飯を罐
もしくは袋等の容器に充填しレトルト殺菌を行な
つて製造されていたが、洗米後直ちに炊飯する場
合原料米の水分含量の違いにより、又炊飯容器内
の各部位（例えば上中下）の出来上り水分含量の
差により、均一な炊飯、即ち均一な澱粉粒のα化
を行なえず、炊き上げたといつても生煮えの状態
となつたり、米飯が崩れた餅化現象を呈したりす
るという欠点があつた。
これらの問題を解決するために、例えば特開昭
50―48152号等で知られるように各種の提案が行
なわれてきているにも拘らず、なお充分な効果が
得られていない実情である。
本発明はこれらの欠点を解決することを目的と
するもので、従つて、本発明の目的は従来の米飯
調理食品の欠点とされてきた品質の不均一性を、
原料米の水分含量を調整することによつて解消し
均一な水分と食感を有する調理済米飯レトルト食
品の製造を可能ならしめることである。
即ち、本発明は洗米後、含水させた米を水切り
し、あらかじめ加熱した後、さらにこの処理米を
適切な量の水と共に密閉可能な容器に充填し反転
吸水させた後、レトルト調理殺菌する事を特徴と
する米飯レトルト食品の製造法であり、この場
合、
(1) 予め水洗等の工程を経て15〜40％の水分含量
に吸水膨潤させた米粒を金網板又は金網篭等に
可能な限り薄く広げ、100〜135℃で１次加熱処
理するか、或いは洗米後30〜40％含水した生米
を高周波加熱等で第１次加熱処理する。
(2) (1)で得た処理米を罐詰容器、半剛性金属容器
あるいは可塑性樹脂等の柔軟性フイルムの密閉
容器（所謂レトルトパウチ）に入れて、常法に
よる炊飯方法での理想状態になるまでの水分を
新たに加え充分均一な吸水を行ないシールす
る。
(3) 次いでこれをレトルト内で殺菌する。殺菌温
度は罐詰を除いたフレキシブルパウチ、半剛性
容器の場合100℃〜140℃の高温殺菌が可能であ
る。特に含気シールの場合は密閉容器内内圧に
打ち勝つだけの外圧を圧縮空気等により調整
し、破袋もしくは破罐を防止することが必要で
ある。
(4) 殺菌終了後常法の冷却過程を経て製品とす
る。
以上の工程において、
(1)の工程は、本発明法に必要不可欠のものであ
つて、この操作により米粒ミセルの構造を緩和さ
せ、且つミセル内の米澱粉粒の吸水膨潤をレトル
ト殺菌時に容易ならしめる所謂湿熱処理の工程で
ある。この工程の特徴は原料米（例えば精白米）
を15〜40％、好ましくは30％程度の可成り低い加
水量に調整含水させて100℃以上の高温加熱を行
なうか、もしくは高周波加熱等の操作により急速
な内部からの加熱を行なう点にある。
(2)の工程は一次加熱処理された米粒を密閉容器
に充填し水を加えて充分な吸水を行ない均一な含
水量とするもので本発明の最重要な操作となつて
いる。従つて、この工程で加えられる加水量は、
一次加熱処理米の水分によつて自由に変える事が
出来、常法で炊き上げる米飯の水分量との差額分
だけ加えればよく、また吸水時間中に反転機によ
つて回転させることによつて充分均一な含水量と
することが必要である。ちなみに反転機を使用し
て回転吸水させた場合と反転機を使用せず反転さ
せなかつた場合との白米レトルト炊飯の水分含量
は下表の通りであり、均一な含水量の製品を得る
ためには反転吸水させることが必須条件であるこ
とが明らかである。
The present invention relates to a method for producing a cooked rice retort food that has a uniform texture that is neither watery nor undercooked and can be stored for a long time at room temperature. This invention relates to a method for producing retort cooked rice food, which is characterized in that the treated rice is heated in advance, then filled in a sealable container with an appropriate amount of water, inverted to absorb water, and then sterilized by retort cooking. be. Conventionally, retort rice food was produced by cooking the rice using the normal rice cooking method immediately after washing the rice, filling the cooked rice into a container such as a can or bag, and sterilizing it in a retort. In some cases, due to differences in the moisture content of the raw rice, and differences in the finished moisture content of each part of the rice cooking container (for example, top, middle, and bottom), uniform cooking of rice, that is, uniform gelatinization of starch granules, may not be possible. The drawbacks were that the rice was always undercooked, and the rice would crumble and become cakey. In order to solve these problems, for example,
Although various proposals have been made, such as in No. 50-48152, the reality is that sufficient effects have not yet been achieved. The purpose of the present invention is to solve these drawbacks. Therefore, the purpose of the present invention is to solve the non-uniformity of quality, which has been considered a drawback of conventional cooked rice foods.
The problem is solved by adjusting the water content of raw rice, and it is possible to produce cooked rice retort food having uniform water content and texture. That is, the present invention involves draining the water-retained rice after washing the rice, heating it in advance, filling the treated rice with an appropriate amount of water in a sealable container, inverting the rice to absorb water, and then sterilizing it by retort cooking. In this case, (1) Rice grains that have undergone a process such as washing with water to absorb water and swell to a moisture content of 15 to 40% are placed on a wire mesh plate or wire mesh basket as much as possible. The rice is spread thinly and subjected to a primary heat treatment at 100 to 135°C, or raw rice with a moisture content of 30 to 40% after washing is subjected to a primary heat treatment using high frequency heating or the like. (2) Place the treated rice obtained in (1) into a canned container, semi-rigid metal container, or airtight container made of flexible film such as plastic resin (so-called retort pouch), and bring it to the ideal state using the conventional rice cooking method. Add new water until it becomes dry, absorb water evenly, and seal. (3) Next, sterilize this in the retort. High-temperature sterilization is possible at 100°C to 140°C for flexible pouches and semi-rigid containers, excluding canned packaging. In particular, in the case of air-containing seals, it is necessary to adjust the external pressure with compressed air or the like to overcome the internal pressure of the closed container to prevent bag or can breakage. (4) After sterilization, the product is made into a product through the usual cooling process. In the above steps, step (1) is essential for the method of the present invention, and this operation relaxes the structure of the rice grain micelles and facilitates water absorption and swelling of the rice starch grains within the micelles during retort sterilization. This is a so-called moist heat treatment process. This process is characterized by raw rice (e.g. polished rice)
Adjust the water content to a fairly low amount of 15 to 40%, preferably around 30%, and then heat the product to a high temperature of 100°C or higher, or heat it rapidly from the inside using high-frequency heating or other operations. . Step (2) is the most important operation of the present invention, in which the rice grains that have been subjected to the primary heat treatment are packed in a closed container and water is added to ensure sufficient water absorption to make the water content uniform. Therefore, the amount of water added in this step is
The moisture content of the primary heat-treated rice can be changed freely by adding only the difference between the moisture content of rice cooked in the conventional method, and by rotating it with an inverter during the water absorption time. It is necessary to have a sufficiently uniform water content. By the way, the moisture content of retort-cooked white rice when water is absorbed by rotation using an inversion machine and when it is not inverted without using an inversion machine is as shown in the table below.In order to obtain a product with a uniform moisture content, It is clear that inversion water absorption is an essential condition.
【表】
本発明の新しい特徴となつている含気シール操
作は例えば柔軟性のパウチもしくは罐詰から内容
物を容易に取り出せるように配慮したもので、本
発明の重要な要素となつている。従つて、空気混
入量も、レトルト殺菌時の熱伝導あるいは空気分
圧の増大を考慮して５〜20％が限界である。
(3)の工程は、通常の炊飯及び殺菌の工程であ
り、この工程により完全な炊飯が行なわれる。
本発明では、以上の段階を経ることによつて、
従来不可能視されてきた均一な水分と食感を有す
る長期保存可能な調理済米飯の製造を可能とし、
食味、食感共非常に優れた製品が得られるもので
ある。
以下、実施例を以つて本発明を詳述する。
（実施例 １）
粳精白米１Kgを流水中で約５分間洗米し、水を
ザル切りし、１時間放置した（水分含量26.5
％）。次にこれを温度110℃、圧力1.4Kg／cm2のオ
ートクレープ中で約20分間処理し、この処理米
（水分含量24.3％）110ｇづつを袋詰し、次いで重
量が夫々200ｇに達するまで注水した。これに、
若干量の含気をしてパウチ詰密封シールして30〜
60分間室温放置し、その間に一回反転させた。次
いで、常法通りこれを110℃で10分間レトルト殺
菌した後、必要あらば90℃30分位の蒸しを行な
い、袋詰あるいは罐詰の上下を反転させて、水ま
たは蒸気を米粒に均一に分散せしめた。以上の全
操作を経て目的とする調理済米飯を得た。
（実施例 ２）
アミロペクチンを主体とする糯米の炊飯につい
ては（実施例１）の炊飯方式とは自ら異なるが、
基本的には一次加熱の湿熱処理が必須要件となつ
ている。
糯米２Kgを流水中で約５分間洗米し、ザルに入
れて水切りを行ない30分間放置することにより水
分含量を27.3％とした。これを金網篭もしくは金
網板に可能な限り薄く広げ（約１cmの厚さ）110
℃のオートクレープ中で約20分間の湿熱処理を行
ない、この一次加熱処理米120〜125ｇを別に茹で
たアズキ適量と共に密閉容器に入れ、予め用意し
たアズキ茹汁65mlを加えて含気シールした。密封
後、常温で30〜60分間放置したが、この際容器を
数回反転させた。これをレトルト中にて120℃で
10分間加圧加熱し、常法通りのレトルト内冷却工
程を経て、目的とする殺菌調理済の赤飯を得た。
（実施例３）赤飯
精白米（もち米）１Kgを洗米し、40℃前後の水
中に２〜３時間浸漬後５分間水切したところ1.4
Kgになつた。次にコンベヤー方式の電子レンジの
コンベヤーに米粒をのせ2450MHz、600Wで1.5分
間の一次加熱を行なつたところ、1.2Kgになつ
た。この一次加熱処理米125〜130ｇを茹でササゲ
15ｇと共に密閉容器に入れ、別に用意した45℃の
２％NaCl入ササゲ茹汁55mlを加えて密封後、常
温にて回転を加えながら30分放置した。
これをレトルト中にて（120℃20分間）加圧加
熱し、常法通りのレトルト内冷却工程を経て調理
済殺菌の赤飯を得た。かくして得た赤飯は10分間
温めるだけで常法で調理したものに比べ遜色ない
美味を有し、かつ保存性の高いものであつた。
（実施例４）白飯
精白米（うるち米）１Kgを洗米し、45℃の温湯
に0.5〜１時間浸漬して５分間水切し、得られた
白米1.25Kgを次にコンベヤー方式の電子レンジコ
ンベヤーにのせ、600Wで1.5分間一次加熱処理を
行なつたところ、重量が1.15Kgになつた。この加
熱処理米115ｇと45℃の湯85mlを密封容器に入
れ、密封後、常温にて回転を加えながら30分放置
し、次いでこれに回転を加えながら110℃40分加
圧加熱した後、常法通りのレトルト内冷却工程を
経て、調理済殺菌の白飯を得た。殺菌加熱を110
℃位の比較的低温に設定する事により、飯粒の表
面の変色がなく、常法炊飯の白飯に比べ色味とも
劣らない飯を得た。
実施例１〜４から得られた本発明方法による調
理済米飯の食味および食感は、第１表に示すよう
に訓練された専門パネル５名の判定結果によれ
ば、同一配合で炊飯した後レトルト殺菌した従来
法に比較し優るとも劣らないものであつた。[Table] The pneumatic sealing operation, which is a new feature of the present invention, is designed to allow easy removal of contents from, for example, flexible pouches or cans, and is an important element of the present invention. Therefore, the limit for the amount of air mixed in is 5 to 20%, taking into consideration heat conduction during retort sterilization or an increase in air partial pressure. Step (3) is a normal rice cooking and sterilization process, and complete rice cooking is achieved through this process. In the present invention, by going through the above steps,
It makes it possible to produce cooked rice that can be stored for a long time and has uniform moisture and texture, which was previously thought to be impossible.
A product with excellent taste and texture can be obtained. Hereinafter, the present invention will be explained in detail with reference to Examples. (Example 1) Wash 1 kg of polished white rice in running water for about 5 minutes, drain the water in a colander, and leave it for 1 hour (moisture content 26.5
%). Next, this was treated in an autoclave at a temperature of 110℃ and a pressure of 1.4Kg/ cm2 for about 20 minutes, and the treated rice (moisture content 24.3%) was packed into bags of 110g each, and then water was added until the weight reached 200g each. did. to this,
Add a small amount of air and seal in a pouch for 30~
It was left at room temperature for 60 minutes, and was inverted once during that time. Next, retort sterilize it at 110℃ for 10 minutes as usual, then steam it for about 30 minutes at 90℃ if necessary, and turn the bag or canned upside down to spread water or steam evenly over the rice grains. It was dispersed. Through all the above operations, the desired cooked rice was obtained. (Example 2) The cooking method of glutinous rice mainly containing amylopectin is different from the rice cooking method of (Example 1), but
Basically, moist heat treatment for primary heating is an essential requirement. 2 kg of glutinous rice was washed under running water for about 5 minutes, placed in a colander to drain, and left to stand for 30 minutes to bring the moisture content to 27.3%. Spread this as thinly as possible on a wire mesh basket or wire mesh board (about 1 cm thick)110
A moist heat treatment was carried out for about 20 minutes in an autoclave at 0.degree. C., and 120 to 125 g of this primary heat-treated rice was placed in an airtight container together with an appropriate amount of separately boiled adzuki beans, and 65 ml of previously prepared adzuki bean boiled water was added to seal the container. After sealing, the container was left at room temperature for 30 to 60 minutes, and the container was inverted several times during this time. This was heated to 120℃ in a retort.
The mixture was heated under pressure for 10 minutes and then cooled in the retort as usual to obtain the desired sterilized cooked red rice. (Example 3) Sekihan 1 kg of polished rice (glutinous rice) was washed, soaked in water at around 40°C for 2 to 3 hours, and then drained for 5 minutes.
I became Kg. Next, rice grains were placed on the conveyor of a conveyor-type microwave oven and heated for 1.5 minutes at 2450MHz and 600W, resulting in a weight of 1.2kg. Boil 125-130g of this primary heat-treated rice and add black-eyed peas.
15 g was placed in an airtight container, 55 ml of separately prepared cowpea boiled soup containing 2% NaCl at 45° C. was added, the container was sealed, and the mixture was left at room temperature for 30 minutes with rotation. This was heated under pressure in a retort (120°C for 20 minutes) and subjected to a conventional cooling process in the retort to obtain cooked and sterilized red rice. The sekihan thus obtained had a taste comparable to that prepared by conventional methods even after being heated for just 10 minutes, and had a high shelf life. (Example 4) White rice Wash 1 kg of polished rice (non-glutinous rice), soak it in hot water at 45°C for 0.5 to 1 hour, drain for 5 minutes, and then place the resulting 1.25 kg of white rice on a conveyor-type microwave conveyor. When the primary heat treatment was performed at 600W for 1.5 minutes, the weight became 1.15Kg. Put 115 g of this heat-treated rice and 85 ml of 45°C hot water into a sealed container, and after sealing, let it stand at room temperature for 30 minutes while rotating. Next, heat it under pressure at 110°C for 40 minutes while rotating, and then Cooked and sterilized white rice was obtained through the legal cooling process in the retort. Sterilization heating to 110
By setting the temperature to a relatively low temperature of about 0.9°C, there was no discoloration on the surface of the rice grains, and rice was obtained that was comparable in color and flavor to conventionally cooked white rice. As shown in Table 1, the taste and texture of the cooked rice prepared by the method of the present invention obtained from Examples 1 to 4 were determined by five trained expert panelists after cooking with the same ingredients. It was no less superior than the conventional method of retort sterilization.
【表】
＋…通常のもの
…食感、食味ともやや優れているもの
…食感、食味とも非常に優れているもの
尚、本発明方法による米飯レトルト食品は従来
法によるものに比べ水つぽさがなく、ベタつかな
かつた。又、実施例３において従来法と本発明方
法によるものの差異があまりなかつたのは食感、
食味に具の影響が強く出たためと考えられる。
さらに、本発明方法による調理済米飯の密閉容
器内の各部位における水分は第２表の如くであ
り、極めて均一性の高いものであつた。[Table] +...Ordinary food...Slightly better texture and flavor...Very excellent texture and taste Note that the cooked rice retort food made by the method of the present invention has a lower water drop rate than the food made by the conventional method. It wasn't sticky and it wasn't sticky. In addition, in Example 3, there was not much difference between the conventional method and the method of the present invention in terms of texture and texture.
This is thought to be due to the strong influence of the ingredients on the taste. Further, the moisture content in each part of the cooked cooked rice according to the method of the present invention in the airtight container was as shown in Table 2, and was highly uniform.
【表】
以上の実施例からも明らかなように、本発明方
法によれば、従来欠点とされていた米飯レトルト
食品の品質の不均一性を解消することができ、食
味、食感に優れ、保存性の高い調理済米飯レトル
ト食品を製造することが可能である。[Table] As is clear from the above examples, according to the method of the present invention, it is possible to eliminate the non-uniformity in the quality of cooked rice retort food, which has been considered a drawback in the past, and it has excellent taste and texture. It is possible to produce cooked rice retort food with high shelf life.