【発明の詳細な説明】[Detailed description of the invention]
本発明は水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及び
５〜20％の空気と共に密閉可能な容器に充填し、
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缶
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な各種の提案が行わ
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、
原料米の水分含量の調整と炊飯の進行度合とを調
整し含気シール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
適切な量の水及び５〜20％の空気と共に密閉可能
な容器に充填し、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、
（） 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高周波加熱等で第
１次加熱処理する。
（） （）で得た処理米を缶詰容器、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含気
シールする。
（） 次いでこれをレトルト内で殺菌する。殺
菌温度は缶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。特に含気シールのため密閉容器内内圧
に打ち勝つだけの外圧を圧縮空気等により調整
し、破袋もしくは破缶を防止することが必要で
ある。
（） 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、
（）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。
（）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
な含水量とする点が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
法で炊き上げた飯の水分量との差額分だけ加えれ
ばよい。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缶詰か
ら内容物を容易に取り出せるよう配慮したもの
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。
（）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、
従来不可能とされてい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が可能となり、食
味、食感共非常に優れた製品の製造が可能となつ
たものである。
以下、実施例を以つて本発明を詳述する。
〔実施例１〕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２〕（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。
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.
After washing the rice, draining the hydrated rice and preheating it, the treated rice is further filled into a sealable container with an appropriate amount of water and 5 to 20% air,
This invention relates to a method for producing retort cooked rice food, which is characterized by sterilization during retort cooking. Traditionally, rice retort 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 those known in No. 48152, the actual situation 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.
To solve this problem by adjusting the moisture content of raw rice and the degree of progress of rice cooking, and sealing the rice to contain air, thereby making it possible to produce a cooked rice retort food having uniform moisture content and texture. That is, in the present invention, after washing the rice, draining the hydrated rice and preheating it, the treated rice is further filled into a sealable container with an appropriate amount of water and 5 to 20% air, and then retort cooking and sterilization. This is a method for manufacturing retort cooked rice food, which is characterized by: () 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 subjected to a primary heat treatment using high frequency heating, etc. do. () Put the treated rice obtained in () into a canning container, semi-rigid metal container, or airtight container (so-called retort pouch) made of flexible film such as plastic resin.
Water is added to the rice until it reaches the ideal state using the conventional rice cooking method, and the water is sufficiently and uniformly absorbed to form an air-containing seal. () This is then sterilized in the retort. High-temperature sterilization is possible at 100°C to 140°C for flexible pouches and semi-rigid containers, excluding canned goods. In particular, for air-containing seals, it is necessary to use compressed air or the like to adjust an external pressure sufficient to overcome the internal pressure of the closed container to prevent bags or cans from breaking. () After sterilization, the product is made into a product through a conventional cooling process. In the above steps, the step () is essential to 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. The feature of this process is that raw rice (for example, polished rice) is adjusted to a fairly low water content of 15 to 40%, preferably around 30%, and then rapidly heated from the inside using operations such as high-frequency heating. be. An important operation in the step () is to fill the rice grains that have been subjected to the primary heat treatment into a closed container and add water to ensure sufficient water absorption to achieve a uniform moisture content. Therefore, the amount of water added in this step can be freely changed depending on the moisture content of the primary heat-treated rice, and it is only necessary to add the amount of water that is the difference between the amount of water and the amount of water in conventionally cooked rice. The pneumatic sealing operation, which is a new feature of the present invention, is designed to facilitate the 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. The process in parentheses 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 has now become possible to produce cooked rice that has uniform moisture and texture and can be stored for a long time, which was previously considered impossible, and it has become possible to produce products with excellent taste and texture. Hereinafter, the present invention will be explained in detail with reference to Examples. [Example 1] Sekihan 1 kg of polished rice (glutinous rice) was washed, soaked in water at around 40℃ for 2 to 3 hours, and then drained for 5 minutes.1.4
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 15g of black-eyed peas.
2% at 45℃ prepared separately.
After adding 55 ml of boiled cowpea juice containing Nacl and sealing the container, it was left for 30 minutes at room temperature 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 2] (White rice) 1 kg of polished rice (non-glutinous rice) is washed, soaked in hot water at 45°C for 0.5 to 1 hour, and drained for 5 minutes. The resulting 1.25 kg of white rice is then transferred to a conveyor-type microwave conveyor. When the sample was placed on a plate and subjected to primary heat treatment 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. The taste and texture of the cooked rice prepared by the method of the present invention obtained from the examples was determined by five trained expert panelists as shown in Table 1. It was as good as the conventional method.
【表】
＋…通常のもの
…食感、食味ともやゝ優れているもの
…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ふつくらとした炊き上りで水
つぽさがなく、ベタつかなかつた。又、実施例１
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... Food that has slightly better texture and taste... Food that has very good texture and taste. The cooked rice retort food produced by the method of the present invention is less plump than that produced by the conventional method. It was perfectly cooked and not watery or sticky. Also, Example 1
The reason that there was not much difference between the conventional method and the method of the present invention is thought to be due to the strong influence of the ingredients on the texture and 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.