JPS6339225B2 - - Google Patents
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- Publication number
- JPS6339225B2 JPS6339225B2 JP56096032A JP9603281A JPS6339225B2 JP S6339225 B2 JPS6339225 B2 JP S6339225B2 JP 56096032 A JP56096032 A JP 56096032A JP 9603281 A JP9603281 A JP 9603281A JP S6339225 B2 JPS6339225 B2 JP S6339225B2
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- phosphor
- measured
- sterilization
- sensor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Landscapes
- Food Preservation Except Freezing, Refrigeration, And Drying (AREA)
Description
〔発明の詳細な説明〕
本発明は密封包装体の殺菌方法に関するもの
で、より詳細には密封包装体をマイクロ波により
殺菌する方法の改良に関する。
近年、包装食品の加熱殺菌にマイクロ波加熱を
応用する試みがなされている。マイクロ波はプラ
スチツク等の誘電体損失の少ない包装材を殆んど
加熱せず透過する特徴を有する一方で、その発熱
機構が食品内部の双極子が、交流電界中におかれ
ると、電界の時間的変化に対応して双極子の回転
振動が起こり、分子の摩擦によつて発熱する特徴
を有しているために、誘電損失の大きい食品は内
部から効率よく加熱できる。この特徴によつて、
マイクロ波は食品工業の分野において広く利用さ
れており、食品の乾燥、冷凍食品の解凍、殺菌加
工が実用化されいる。たとえば、加熱殺菌では、
ハムソーセージの殺菌、パン菓子のカビ発生防
止、イカ珍味のカビ防止のための殺菌などの応用
例が知られている。しかし、これら公知の方法で
は、殺菌対象となる微生物は耐熱性が極めて低
く、80〜90℃で10〜20分程度で完全に殺滅するこ
とが出来るため、マイクロ波加熱によつて100℃
付近まで品温を上昇させれば、殺菌効果が得られ
るため特に品温を測定する必要がなかつた。
しかしながら、包装食品を変敗させる微生物に
は100℃以下の加熱では殺滅できない高い耐熱性
を有するものが存在しており、缶詰、びん詰レト
ルト食品同様100℃以上の高温で処理しなければ
完全に保存し得る包装食品を製造することが不可
能なことはマイクロ波加熱殺菌においても同様で
ある。このため、法律的にも100℃以上で加熱殺
菌する包装食品にあつては、加熱処理時の厳密な
温度を記録することが義務づけられている。それ
にもかかわらず、マイクロ波加熱殺菌に関する公
知の方法及び装置においては有効な温度測定方法
は明示されているものはない。
現在までマイクロ波で包装食品及び食品を加熱
殺菌する場合に使用されている測温方法として
は、ある温度になると変色する感温ラベル又はサ
ーモペイント、グリシン―グルコース混合溶液の
変色、蛋白凝固物の凝固点等が利用されているが
これらの方法では、最高到達温度や工程中で蒙む
つた全熱履歴がわかるのみで、熱電対やサーミス
ターを使用する従来の測温方法のように加熱の時
間的経過にともなつた加熱温度を連続的に測定す
ることが不可能であり、殺菌程度を温度―時間関
係で管理することは不可能であつた。このため、
マイクロ波加熱による包装食品の100℃以上の温
度での殺菌は確実に包装食品が殺菌できたかどう
かの管理が不可能であつたため実用化されないで
いる。
従つて、本発明の目的は、容器内に充填され密
封された食品について、加熱の時間的経過にとも
なつた加熱温度を正確に測定しつつマイクロ波加
熱殺菌する方法を提供するにある。
本発明の他の目的は、マイクロ波加熱殺菌に際
して、マイクロ波の影響下においても食品の加熱
履歴を正確に測定して、長期間の保存に耐える品
質良好な加熱殺菌包装食品を製造し得る殺菌方法
を提供するにある。
本発明によれば、マイクロ波に対して透過性を
有する容器内に被殺菌物品を充填してなる密封包
装体にマイクロ波を照射し、マイクロ波照射下に
ある密封包装体の温度の時間的経過を、蛍光体温
度センサーを用いて、蛍光体の蛍光波長領域での
強度の温度依存性に基づいて測定し、該蛍光体セ
ンサーで測定される温度が100℃以上となり、且
つ式
F=∫t plog-1(T−121.1/Z)dt …(1)
式中、log-1はアンチログの意味であり、Tは
蛍光体センサーで測定される温度(℃)を表わ
し、tはマイクロ波照射開始後の時間(分)を表
わし、Zは微生物の温度依存性値、所謂Z値
(℃)である、
で表わされる積分値(F)が3.2以上となるに十分な
時間マイクロ波の照射を続けることを特徴とする
密封包装体の殺菌方法が提供される。
先ず、前記式(1)の意味するところについて説明
する。log-1は、加熱殺菌分野で常用され、通常
アンチログ(Anti―log)と称している。意味す
るところは、細菌芽胞の耐熱性試験によつて得ら
れている加熱致死時間曲線(通常Thermal
Death time curve.TDT曲線)から次式が得ら
れる。
log t=121.1−T/Z …(2)
この式(2)で、tは加熱温度T(℃)での致死時
間(分)であり、ZはTDT曲線[縦軸:致死時
間(分,対数)、横軸:加熱温度(℃)]におい
て、致死時間を1/10にするために必要な温度
(℃)を示しており、菌の熱抵抗性の強弱を示す
指標である。(2)式は通常次式で示して使用する。
t=log-1121.1−T/Z …(3)
このtの逆数1/tはその加熱時間での致死率
となる。これをLとすると次式が得られる。
L=1/t=1/log-1121.1−T/Z
=log-1T−121.1/Z …(4)
全殺菌工程(0〜tまで)では、全殺菌の積分
値(F)は
F=∫t pL dt
=∫t plog-1T−121.1/Zdt
となる。
食品を変敗する細菌のZ値は多少の変動がある
が、大部分が10(℃)近くにあり、この値で代表
しても特に問題はない。又、最も注意する必要が
あるボツリヌス菌のZ値は10(℃)であることか
ら、この値で代表してもよいことがわかる。
本発明において、Fが3.2以上であることの意
味は、加熱殺菌包装では、殺菌対象細菌として少
なくともボツリヌス菌芽胞を殺滅する必要があ
り、この菌の耐熱性が正確にはF=3.12であり、
本発明ではこれに基づき3.2とした。
本発明において、温度Tを、従来の熱電対やサ
ーミスタに代えて、蛍光センサーで測定している
ことの意義は次の通りである。
本発明の重要な特徴の一つは、マイクロ波照射
下にある密封包装体の温度の時間的経過を、螢光
体温度センサーを用いて、螢光体の螢光波長領域
での光強度の温度依存性に基ずいて測定すること
にある。先ず、加熱殺菌下にある密封包装体の温
度を時間的経過に従つて測定する普通の方法は、
温度センサーとして熱電体やサーミスタを用いる
方法であるが、マイクロ波による加熱殺菌の場合
には、温度センサーからの電波漏洩があり、更に
温度センサーの先端に電界が集中するため、正確
な品温の測定が困難となる。これに対して、本発
明に従い、螢光体温度センサーをマイクロ波照射
下にある密封包装体の温度の測定に使用すると、
センサーへ電界が集中することなく、また温度を
螢光信号の形で取出せるため、電波漏洩の問題も
有効に解消され、密封包装体の品温を正確にしか
も時間的経過に従つて測定できるようになる。
本発明に用いる螢光体温度センサー及びこれに
よる温度測定の原理そのものは、米国特許第
4075493号及び第4215275号明細書により既知のも
のであるが、これをマイクロ波殺菌条件下にある
密封包装体の品温の測定に使用し、しかも測定さ
れる温度の時間的経過をマイクロ波照射と関連さ
せることは本発明前全く未知のことである。
本発明において、被殺菌物品を充填する容器と
してはマイクロ波に対して透過性を有する密封可
能な容器であれば、任意のものを用いることがで
きる。かかる容器は、袋のような可撓性容器であ
つても、或いはカツプ、広口ビンのような剛性の
ある容器であつてもよい。これらの容器は誘電損
失の少ない材料、例えば熱可塑性或いは熱硬化性
のプラスチツク、例えばポリエチレン、ポリプロ
ピレン等のオレフイン系樹脂;ポリエチレンテレ
フタレートの如きポリエステル樹脂;ナイロン6
の如きポリアミド樹脂;ポリカーボネート;ポリ
塩化ビニル、塩化ビニリデン系樹脂等で構成され
ていることが好ましく、その他ガラスから成る容
器も用いることができる。
容器内に充填する被殺菌物品としては、これに
限定されるものでないが、液状或いはペースト状
の食品や飲料、例えばコーヒ、紅茶;レモンジユ
ース、オレンジジユース、プラムジユース、ブド
ージユース、イチゴジユース等のストレート・ジ
ユース、或いはネクター等の加工果汁飲料を含む
果汁飲料;トマトジユース、各種野菜ジユースを
含む蔬菜汁飲料;乳酸菌飲料;調理済カレー、調
理済ハヤシ、ボルシチ、ビーフシチユーの如きシ
チユー類、ミートソースの如きグレビー類;酢
豚、スキヤキ、八宝菜、中華風五目煮、アスパラ
ガス煮、ビーンズ、マグロのクリーム煮等の水煮
野菜、魚及び肉類;コンソメスープ、ポタージユ
スープ、みそ汁、豚汁、ケンチン汁の如きスー
プ;米飯、赤飯、ヤキ飯、五目飯、ピラフ、カユ
の如き米食品;スパゲテイ、ソバ、ウドン、中華
ソバ、マカロニの如きメン類;チヤーハン・スー
プ用或いは中華ソバ・スープ用複合調味料;ユデ
小豆、ゼンザイ、汁粉、アンミツ、ミツマメ、プ
リン、ゼリー、水ヨウカン等の嗜好食品;肉団
子、ハンバーグ、コンビーフ、ハム、ソーセー
ジ、焼魚、クンセイ、ベーコン、カマボコ等の加
工水産乃至蓄産製品;ミカン、ピーチ、パイナツ
プル、チエリー、オリーブ等の果実製品;例えば
シヨウ油、ソース、食酢、みりん、ドレツシン
グ、マヨネーズ、ケチヤツプ、食用油、味噌、ラ
ード、ケチヤツプなどの調味料;豆腐、ジヤム、
バター、マーガリン等の嗜好品等を挙げることが
できる。
容器への内容物の充填は、冷間及び熱間でも行
うことができ、容器の密封はヒートシール、巻
締、密栓等のそれ自体公知の方法で行うことがで
きる。尚、容器の密封に際して、容器のヘツドス
ペース内の酸素を、水蒸気噴射、窒素置換等の手
段で除去しておくこともできる。
本発明において、螢光体温度センサーとして
は、螢光波長領域での光強度が螢光体の温度によ
つて変化する螢光体の層が使用される。好適な螢
光体は、希土類元素のオキシサルフアイドであ
り、この化合物は希土類元素でドーピング処理さ
れていてもよい。これらの螢光体は、下記式
M2O2S・nX
式中、Mはランタン、ガドリニウム、イツトリ
ウム等の希土類元素であり、Xは希土類元素から
成るドーピング成分を表わし、nはM当り0.01乃
至10原子%となる数である、
で表わされるものである。上述した螢光体センサ
ーから温度を螢光信号として取出すために、紫外
線光源及び螢光検出機構を設け、この螢光体セン
サーと紫外線光源及び螢光検出機構とを光フアイ
バーにより夫々接続する。かくして、光源からの
紫外線は光フアイバーを通して螢光体層に照射さ
れて螢光体は励起され、螢光体層の温度に特有の
強度の螢光は、光フアイバーを通して螢光検出機
構に送られる。この螢光検出機構からの信号は、
信号プロセシング機構において、光強度の温度依
存性に基ずいて、温度表示信号に変換され、温度
として表示される。
加熱殺菌すべき包装体の温度を測定するため
に、上記螢光体センサーを包装体に固定する。こ
の固定の仕方を示す第1図において、サンプリン
グ用剛性容器1の器壁に孔をあけ、この孔にポリ
テトラフルオロエチレン製のパツキンググラウン
ド2を嵌込み、これを介して光フアイバーから成
るプローブ3を通し、螢光体温度センサー4が包
装体中心に位置するように保持させる。また、パ
ウチの如き柔軟な容器の場合には、第2図に示す
通り、サンプリング容器1aの壁にやはり孔をあ
け、この孔にパツキング・グラウンド2を嵌込
み、これを介してプローブ3を通し、プローブホ
ルダー5により、センサー4がやはり包装中心に
位置するようにする。
本発明においては、容器内の食品等は、通常の
加熱殺菌とは異なり、全体にわたつて一様な加熱
が行われるため、温度センサーを包装中心に位置
させることが必らずしも必要でなく、例えば容器
壁に近接した部分に螢光体温度センサーを位置さ
せても、或いは容器壁面に温度センサーを接触さ
せても、品温の測定がかなり正確に行われること
が理解されるべきである。
本発明において、マイクロ波による加熱殺菌は
任意の方法で行なうことができる。マイクロ波と
しては、周波数が915及び2450MHzのものである
がこれ以外の周波数の電磁波も勿論使用される。
マイクロ波の照射は、マグネトロン等のマイクロ
波発生装置から、導波管を介して殺菌室内にマイ
クロ波を導入することにより容易に行われ、この
際、マイクロ波を殺菌室内に一様に照射するため
に、導波管出口或いは更に殺菌室の適当な位置に
フアンを設けることもできる。マイクロ波の出力
は、殺菌に必要な熱量によつても著しく相違する
が、一般には、1個の包装体のマイクロ波照射に
よる殺菌が30秒乃至30分間の時間で完了するよう
に、出力を定めるのが望ましい。勿論、マイクロ
波の照射は連続して行つてもよいし、断続して行
つて品温が一定の範囲にあるようにしてもよい。
マイクロ波の照射は、連続的にもバツチ式にも
行うことができる。連続式の場合には、包装体を
コンベヤベルト等の搬送機構に載せてマイクロ波
照射下の殺菌室内に連続的に或いは間欠的に送れ
ばよく、バツチ式の場合には、殺菌室内に所定量
の包装体を詰め込み、マイクロ波の照射を行うの
がよい。
殺菌室内の雰囲気は常圧でもよいし、空気加圧
下でもよい。例えば、包装容器が耐圧容器である
場合や、殺菌温度が比較的低い場合には、殺菌室
雰囲気は常圧であつてよい。勿論、殺菌雰囲気
を、包装体内の蒸気圧の全部乃至は一部を打消す
ように加圧しておけば殺菌時における包装容器或
いは密封部の破損を有効に防止することができ
る。一般には殺菌室内を1.2乃至3.0Kg/cm2ゲージ
程度に加圧しておくことが望ましい。殺菌室内を
加圧し連続的にマイクロ波殺菌を行う場合には、
殺菌室の入口及び出口には、シール部を設けるの
がよい。
本発明において、マイクロ波殺菌室内に導入す
る密封包装体は、殺菌温度への昇温時間を短縮す
るために、予じめ予備加熱しておくことが望まし
い。一般に、密封包装体の品温を60乃至90℃とし
ておくことがこの目的に好都合である。このため
には、内容物の熱間充填や、熱風や熱水蒸気によ
る包装体の予備加熱が使用される。
本発明によれば、マイクロ波殺菌すべき密封包
装体のグループに、前述した殺菌温度サンプリン
グ用の密封包装体を含ませることにより、マイク
ロ波照射条件下において、品温の時間的経過を正
確に測定することができる。即ち、この方法によ
れば、殺菌室内には、マイクロ波の影響を受けな
い螢光体温度センサー及び光フアイバー・プロー
ブが位置するのみであり、しかもこれらの測温具
は、殺菌時における熱水、熱水蒸気、圧力等によ
る影響も何等受けることなく、マイクロ波殺菌下
にある品温のみを、螢光の強度として正確に測定
できる。
本発明においては、螢光体センサーで測定され
る温度が100℃以上となり且つ式
F=∫t plog-1(T−121.1/Z)dt
式中、Tは螢光体センサーで測定される温度
(℃)を表わし、tはマイクロ波照射時間を表わ
し、Zは微生物の温度依存性値である、
で表わされる積分値(F)が3.2以上となるに十分な
時間マイクロ波の照射を続けることも極めて重要
である。
既に前述した如く、包装食品中の微生物の殺滅
効果は、温度と時間との組合せに依存することが
知られている。本発明においては、マイクロ波殺
菌下にある包装食品の温度を刻々測定し、この温
度が100℃以上、好適には105乃至130℃となり、
しかもこの温度と時間との相関を、前記式の積分
値(F)として算出し、この積分値(F)が一定値以上と
なる迄マイクロ波の照射を続けることにより、長
期間の保存に耐え、しかも品質良好な加熱殺菌包
装食品を製造することが可能となる。
この積分値(F)の算出は、マイクロ波照射開始後
の時間の信号と、この時間における温度検出信号
とを、コンピユーターに入力させて演算を行わせ
ることにより自動的に行わせることができる。
前記式において、微生物の温度依存性値は所謂
Z値であり、バチルス・コアギユランスの場合の
7からバチルス・ズブチリスの場合の14迄の範囲
内で変化し得る。
本発明において、マイクロ波照射終了後の密封
包装体は、内容物の所謂煮すぎによる品質劣化を
防止するために、強制冷却するのが望ましい。こ
の冷却は例えば冷風、冷水等の冷却媒体を用いて
行うことができ、包装容器の内圧による破損を防
止するために、殺菌の場合と同様に加圧下で行う
ことができる。一般には、4乃至10分間の時間内
に、品温を50℃以下に迄冷却するのが好ましい。
本発明によれば、マイクロ波照射下にある密封
包装体の品温を正確に測定でき、しかも長期貯蔵
性のある殺菌包装体が得られることは、次の実験
例を参照することにより直ちに明白となろう。
即ち、透明プラスチツク袋状容器に、グリシン
及びグルコースを夫々1/15モルの濃度で含有する
7.7%小麦粉溶液を充填し、密封して包装体を調
製した。また、この密封包装体の或るものには、
市販の示温用のサーモラベルを貼着した。更に、
上記密封包装体の調製時に、螢光体温度センサー
及びクロメル―アルメル(C―A)熱電対を、第
2図に示す位置関係で夫々取付けて、サンプリン
グ用包装体を調製した。
かくして調製した4種類の密封包装体を空気加
圧下で2450MHzのマイクロ波を照射し、4分経過
後に空気加圧下に冷却し、品温を測定した。この
結果を第1表に示す。
[Detailed Description of the Invention] The present invention relates to a method for sterilizing a sealed package, and more particularly to an improvement in a method for sterilizing a sealed package using microwaves. In recent years, attempts have been made to apply microwave heating to heat sterilization of packaged foods. Microwaves have the characteristic of passing through packaging materials with low dielectric loss, such as plastics, with little heating. However, the heating mechanism of microwaves is that when the dipole inside the food is placed in an alternating current electric field, the time of the electric field increases. Rotational vibrations of dipoles occur in response to changes in energy, and heat is generated by the friction of molecules, so foods with large dielectric loss can be efficiently heated from the inside. Due to this feature,
Microwaves are widely used in the food industry, and are put to practical use in drying foods, thawing frozen foods, and sterilizing them. For example, heat sterilization
Application examples include sterilization of ham sausages, prevention of mold growth in pastries, and sterilization of squid delicacies to prevent mold. However, in these known methods, the microorganisms to be sterilized have extremely low heat resistance and can be completely killed in about 10 to 20 minutes at 80 to 90 degrees Celsius.
There was no need to specifically measure the temperature of the product because a sterilization effect could be obtained if the temperature of the product was raised to a temperature close to that level. However, some microorganisms that cause spoilage of packaged foods have a high heat resistance that cannot be killed by heating below 100℃, and like canned and bottled retort foods, they must be treated at high temperatures of 100℃ or higher. The same applies to microwave heat sterilization, which makes it impossible to produce packaged foods that can be stored for a long time. For this reason, it is legally required for packaged foods that are heat sterilized at temperatures above 100°C to record the exact temperature during the heat treatment. Nevertheless, none of the known methods and devices for microwave sterilization discloses an effective temperature measurement method. Temperature measurement methods currently used when heat sterilizing packaged foods and food products using microwaves include temperature-sensitive labels or thermopaints that change color at a certain temperature, discoloration of glycine-glucose mixed solutions, and methods of measuring protein coagulation. Freezing point, etc. are used, but these methods only determine the maximum temperature reached and the total heat history during the process; unlike traditional temperature measurement methods that use thermocouples and thermistors, these methods do not measure the heating time. It has been impossible to continuously measure the heating temperature over time, and it has been impossible to control the degree of sterilization in terms of the temperature-time relationship. For this reason,
Sterilization of packaged foods by microwave heating at temperatures of 100°C or higher has not been put to practical use because it has been impossible to reliably control whether the packaged foods have been sterilized. Therefore, it is an object of the present invention to provide a method for sterilizing foods filled and sealed in containers by microwave heating while accurately measuring the heating temperature over time. Another object of the present invention is to accurately measure the heating history of foods even under the influence of microwaves during microwave heat sterilization, and to produce heat sterilized packaged foods of good quality that can withstand long-term storage. We are here to provide you with a method. According to the present invention, microwaves are irradiated to a sealed package formed by filling an article to be sterilized in a container that is transparent to microwaves, and the temperature of the sealed package under microwave irradiation is changed over time. The progress is measured using a phosphor temperature sensor based on the temperature dependence of the intensity in the fluorescence wavelength region of the phosphor, and the temperature measured by the phosphor sensor is 100°C or higher, and the formula F=∫ t p log -1 (T-121.1/Z) dt ...(1) In the formula, log -1 means anti-log, T represents the temperature (℃) measured by the phosphor sensor, and t represents the micro It represents the time (minutes) after the start of microwave irradiation, and Z is the temperature dependence value of microorganisms, the so-called Z value (℃). A method for sterilizing a sealed package is provided, the method comprising continuous irradiation. First, the meaning of the above formula (1) will be explained. Log -1 is commonly used in the field of heat sterilization and is usually referred to as anti-log. What this means is that the thermal lethality time curve (usually thermal
The following equation can be obtained from the Death time curve (TDT curve). log t=121.1−T/Z...(2) In this equation (2), t is the lethal time (minutes) at the heating temperature T (℃), and Z is the TDT curve [vertical axis: lethal time (minutes, Logarithm), horizontal axis: heating temperature (°C)] indicates the temperature (°C) required to reduce the lethal time to 1/10, and is an indicator of the strength of the heat resistance of the bacteria. Equation (2) is usually expressed and used as the following equation. t=log -1 121.1-T/Z...(3) The reciprocal of t, 1/t, is the lethality rate at that heating time. Letting this be L, the following equation is obtained. L=1/t=1/log -1 121.1-T/Z =log -1 T-121.1/Z...(4) In the total sterilization process (from 0 to t), the integral value (F) of total sterilization is F =∫ t p L dt =∫ t p log -1 T-121.1/Zdt. The Z value of bacteria that spoil food varies slightly, but most are close to 10 (℃), so there is no particular problem in representing it with this value. Furthermore, since the Z value of Clostridium botulinum that requires the most attention is 10 (°C), it can be seen that this value may be used as a representative value. In the present invention, the meaning of F being 3.2 or more is that in heat sterilization packaging, it is necessary to kill at least Clostridium botulinum spores as bacteria to be sterilized, and the heat resistance of this bacterium is exactly F = 3.12. ,
In the present invention, it is set as 3.2 based on this. In the present invention, the significance of measuring the temperature T with a fluorescent sensor instead of a conventional thermocouple or thermistor is as follows. One of the important features of the present invention is that the time course of the temperature of a sealed package under microwave irradiation is measured using a phosphor temperature sensor, which measures the light intensity in the fluorescence wavelength region of the phosphor. The purpose is to measure based on temperature dependence. First, the usual method of measuring the temperature of a sealed package under heat sterilization over time is as follows:
This method uses a thermoelectric material or thermistor as a temperature sensor, but when heat sterilizing with microwaves, there is radio wave leakage from the temperature sensor, and the electric field is concentrated at the tip of the temperature sensor, making it difficult to accurately determine the temperature of the product. Measurement becomes difficult. In contrast, according to the invention, when a phosphor temperature sensor is used to measure the temperature of a sealed package under microwave irradiation,
Since the electric field does not concentrate on the sensor and the temperature can be extracted in the form of a fluorescent signal, the problem of radio wave leakage is effectively resolved, and the temperature of the sealed package can be measured accurately and over time. It becomes like this. The fluorescent temperature sensor used in the present invention and the principle of temperature measurement using it are disclosed in US Patent No.
4075493 and 4215275, this is used to measure the temperature of a sealed package under microwave sterilization conditions, and the time course of the measured temperature is measured by microwave irradiation. This was completely unknown prior to the present invention. In the present invention, any container can be used to fill the article to be sterilized as long as it is transparent to microwaves and can be sealed. Such a container may be a flexible container such as a bag, or a rigid container such as a cup or a wide mouth bottle. These containers are made of materials with low dielectric loss, such as thermoplastic or thermosetting plastics, such as olefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate; and nylon 6.
It is preferable to use a container made of polyamide resin such as polyamide resin; polycarbonate; polyvinyl chloride, vinylidene chloride resin, etc. Other containers made of glass can also be used. Items to be sterilized to be filled into containers include, but are not limited to, liquid or pasty foods and beverages, such as coffee, black tea; straight fruits such as lemon juice, orange juice, plum juice, budoji youth, and strawberry juice;・Fruit juice drinks including processed fruit juice drinks such as juice or nectar; Vegetable juice drinks including tomato juice and various vegetable juices; lactic acid bacteria drinks; cooked curry, cooked hash, stews such as borscht and beef stew, and gravy such as meat sauce Types: Sweet and sour pork, sukiyaki, Happo-na, Chinese-style boiled vegetables, boiled asparagus, beans, cream-stewed tuna, etc., boiled vegetables, fish, and meat; Consomme soup, potage soup, miso soup, pork soup, kenchin soup, etc. Soup; rice foods such as rice, red rice, fried rice, gomoku rice, pilaf, and kayu; noodles such as spaghetti, soba, udon, Chinese soba, and macaroni; compound seasoning for fried rice soup or Chinese soba soup; red bean Favorite foods such as zenzai, shiruko, sweet bean, mitsumame, pudding, jelly, and water yokan; Processed seafood and farmed products such as meatballs, hamburgers, corned beef, ham, sausages, grilled fish, Kunsei, bacon, and kamaboko; Mandarin oranges, peaches, Fruit products such as pineapple, cherries, and olives; seasonings such as mustard oil, sauce, vinegar, mirin, dressing, mayonnaise, ketchup, cooking oil, miso, lard, and ketchup; tofu, diyam,
Examples include luxury goods such as butter and margarine. The contents can be filled into the container either cold or hot, and the container can be sealed by a method known per se, such as heat sealing, seaming, and sealing. Incidentally, when sealing the container, oxygen in the head space of the container can be removed by steam injection, nitrogen substitution, or the like. In the present invention, the phosphor temperature sensor uses a layer of phosphor whose light intensity in the fluorophore wavelength range changes depending on the temperature of the phosphor. Suitable phosphors are rare earth oxysulfides, the compounds of which may be doped with rare earth elements. These phosphors have the following formula M 2 O 2 S・nX, where M is a rare earth element such as lanthanum, gadolinium, or yttrium, X represents a doping component made of the rare earth element, and n is 0.01 to It is a number that is 10 atomic %, and is expressed as . In order to extract the temperature as a fluorescence signal from the above-mentioned fluorescent sensor, an ultraviolet light source and a fluorescence detection mechanism are provided, and the fluorescent sensor is connected to the ultraviolet light source and the fluorescence detection mechanism by optical fibers, respectively. Thus, ultraviolet light from the light source is applied to the phosphor layer through the optical fiber to excite the phosphor, and the fluorescence with an intensity characteristic of the temperature of the phosphor layer is transmitted through the optical fiber to a fluorescence detection mechanism. . The signal from this fluorescence detection mechanism is
In a signal processing mechanism, based on the temperature dependence of the light intensity, it is converted into a temperature indicating signal and displayed as temperature. In order to measure the temperature of the package to be heat sterilized, the fluorescent sensor is fixed to the package. In FIG. 1 showing this fixing method, a hole is made in the wall of a rigid sampling container 1, a packing ground 2 made of polytetrafluoroethylene is fitted into the hole, and a probe made of optical fiber is inserted through the packing ground 2 made of polytetrafluoroethylene. 3 and held so that the fluorescent temperature sensor 4 is located at the center of the package. In addition, in the case of a flexible container such as a pouch, as shown in FIG. , the probe holder 5 ensures that the sensor 4 is still located at the center of the package. In the present invention, unlike normal heat sterilization, the food inside the container is uniformly heated throughout, so it is not necessarily necessary to position the temperature sensor at the center of the package. It should be understood that the temperature of the product can be measured fairly accurately, for example, even if the fluorescent temperature sensor is located close to the container wall, or even if the temperature sensor is in contact with the container wall. be. In the present invention, heat sterilization using microwaves can be performed by any method. The microwaves have frequencies of 915 and 2450 MHz, but electromagnetic waves with other frequencies can of course also be used.
Microwave irradiation is easily performed by introducing microwaves into the sterilization chamber from a microwave generator such as a magnetron through a waveguide, and at this time, the microwaves are uniformly irradiated into the sterilization chamber. For this purpose, a fan can be provided at the waveguide outlet or even at a suitable location in the sterilization chamber. The output of microwaves varies significantly depending on the amount of heat required for sterilization, but in general, the output is set so that sterilization of one package by microwave irradiation is completed in 30 seconds to 30 minutes. It is desirable to specify. Of course, the microwave irradiation may be performed continuously or intermittently to keep the product temperature within a certain range. Microwave irradiation can be carried out continuously or batchwise. In the case of a continuous type, the package may be placed on a conveyor belt or other transport mechanism and sent continuously or intermittently into a sterilization chamber under microwave irradiation; in the case of a batch type, a predetermined amount is placed in the sterilization chamber. It is best to pack it in a package and irradiate it with microwaves. The atmosphere in the sterilization chamber may be at normal pressure or may be under air pressure. For example, when the packaging container is a pressure-resistant container or when the sterilization temperature is relatively low, the sterilization chamber atmosphere may be at normal pressure. Of course, if the sterilizing atmosphere is pressurized so as to cancel out all or part of the vapor pressure inside the package, damage to the packaging container or the sealed portion during sterilization can be effectively prevented. Generally, it is desirable to pressurize the sterilization chamber to about 1.2 to 3.0 kg/cm 2 gauge. When performing continuous microwave sterilization by pressurizing the sterilization chamber,
It is preferable to provide seals at the entrance and exit of the sterilization chamber. In the present invention, it is desirable that the sealed package introduced into the microwave sterilization chamber be preheated in advance in order to shorten the heating time to the sterilization temperature. Generally, it is convenient for this purpose to maintain the temperature of the sealed package at 60 to 90°C. For this purpose, hot filling of the contents or preheating of the package with hot air or hot steam is used. According to the present invention, by including the above-mentioned sealed package for sterilization temperature sampling in the group of sealed packages to be microwave sterilized, it is possible to accurately measure the time course of product temperature under microwave irradiation conditions. can be measured. That is, according to this method, only a fluorescent temperature sensor and an optical fiber probe, which are not affected by microwaves, are located in the sterilization chamber, and these temperature measuring instruments are not exposed to hot water during sterilization. The temperature of the product under microwave sterilization can be accurately measured as the intensity of fluorescent light without being affected by hot steam, pressure, etc. In the present invention, the temperature measured by the fluorescent sensor is 100°C or higher and the formula F=∫ t p log -1 (T-121.1/Z) dt where T is the temperature measured by the fluorescent sensor The temperature (°C) is expressed, t is the microwave irradiation time, and Z is the temperature dependence value of microorganisms. Continue microwave irradiation for a sufficient time so that the integral value (F) expressed by is 3.2 or more. This is also extremely important. As already mentioned above, it is known that the effectiveness of killing microorganisms in packaged foods depends on the combination of temperature and time. In the present invention, the temperature of the packaged food under microwave sterilization is measured moment by moment, and this temperature is 100°C or more, preferably 105 to 130°C,
In addition, by calculating the correlation between temperature and time as the integral value (F) of the above formula, and continuing microwave irradiation until this integral value (F) exceeds a certain value, it can be stored for a long time. Moreover, it becomes possible to produce heat-sterilized packaged foods of good quality. Calculation of this integral value (F) can be automatically performed by inputting the signal of the time after the start of microwave irradiation and the temperature detection signal at this time into a computer and performing the calculation. In the above formula, the temperature-dependent value of the microorganism is the so-called Z value, which can vary within the range from 7 in the case of Bacillus coagulans to 14 in the case of Bacillus subtilis. In the present invention, it is desirable that the sealed package after the microwave irradiation is forcibly cooled in order to prevent quality deterioration due to so-called overcooking of the contents. This cooling can be performed using, for example, a cooling medium such as cold air or cold water, and can be performed under pressure as in the case of sterilization in order to prevent damage to the packaging container due to internal pressure. Generally, it is preferable to cool the product to a temperature of 50°C or less within a period of 4 to 10 minutes. It is immediately clear from the following experimental examples that according to the present invention, the temperature of a sealed package under microwave irradiation can be accurately measured and a sterilized package with long shelf life can be obtained. Let's become. That is, a transparent plastic bag-like container contains glycine and glucose each at a concentration of 1/15 molar.
A package was prepared by filling with 7.7% flour solution and sealing. In addition, some of these sealed packages include:
A commercially available thermolabel for temperature indication was attached. Furthermore,
When preparing the above-mentioned sealed package, a phosphor temperature sensor and a chromel-alumel (CA) thermocouple were attached in the positional relationship shown in FIG. 2 to prepare a sampling package. The four types of sealed packages thus prepared were irradiated with 2450 MHz microwaves under air pressure, and after 4 minutes had elapsed, they were cooled under air pressure and the product temperature was measured. The results are shown in Table 1.
【表】【table】
【表】
本発明及びC―A熱電対による方法では、他の
二つの方法に比べ、温度―時間関係が定量的に示
すことが出来るが、C―A熱電対を使用したもの
では、同一内容物であるにもかかわらず本発明方
法で測定したものより昇温が早いことを示してい
る。そこで、これら二つの方法から得た加熱、冷
却曲線から積分値(F)が3.2となる条件を求め、そ
の条件で50袋を処理して貯蔵試験したところ、C
―A熱電対を使用して測温したものでは多数の変
敗をみた。
この理由を知るため、C―A熱電対を使用した
温度曲線を検討したところ、第3図に示すよう
に、熱電対を使用したものでは、マグネトロンへ
の通電を止め、マイクロ波発振を止めた瞬間、熱
起電力は急激に下がることがわかつた。この様な
立ち下りの現象は、熱電対の先端に電界が集中
し、先端部分が極度に加熱されるためで、立ち下
り現象後の熱起電力が正しい温度と思われ、熱電
対では、正しい品温が測定できないことがわかつ
た。これに対して本発明では、マグネトロンへの
通電の有無にかかわらず温度の上昇、下降は安定
しており、極めて正確に測定されることが明らか
となつた。同様に、他の測定方法で得た品温測定
結果を示すが、サーモラベル及びグリシン―グル
コース溶液を使用する測定方法が、ある一定温度
にならなければ変色、褐変が生じなく、かつ冷却
時の温度―時間の関係がどのような状態にあるか
明らかでないのに対して、本発明の方法では逐一
正確に把握できることが明らかであることがわか
る。
本発明方法によつて包装中心部の品温を測定し
たもの、および他の方法により殺菌程度が等しい
状態でマイクロ波処理したときの殺菌状態と、出
来上り品質の結果を第2表に示す。
この結果、本発明方法によつて測温した包装食
品は、良好に殺菌処理がほどこされており、かつ
余分の熱履歴を蒙むつていないため品質も良好で
あることがわかるが、他の方法では変敗が生じた
り、加剰加熱の為、品質が低下しており、本発明
方法がマイクロ波加熱を主熱源とした100℃以上
の温度での包装食品の殺菌に極めて効果があるこ
とを示している。[Table] The method using the present invention and the C-A thermocouple can quantitatively show the temperature-time relationship compared to the other two methods, but the method using the C-A thermocouple has the same content. This shows that the temperature rises faster than that measured using the method of the present invention, even though the temperature was measured using the method of the present invention. Therefore, we determined the conditions under which the integral value (F) was 3.2 from the heating and cooling curves obtained from these two methods, and when we processed 50 bags under these conditions and conducted a storage test, we found that C
-Many changes were observed when temperature was measured using A thermocouple. In order to understand the reason for this, we examined the temperature curve using a C-A thermocouple and found that, as shown in Figure 3, when using a thermocouple, electricity to the magnetron was stopped and microwave oscillation was stopped. It was found that the thermoelectromotive force suddenly dropped instantly. This falling phenomenon occurs because the electric field concentrates at the tip of the thermocouple, causing the tip to become extremely heated.The thermoelectromotive force after the falling phenomenon is considered to be the correct temperature; It was discovered that the temperature of the product could not be measured. On the other hand, in the present invention, it has become clear that the temperature rise and fall are stable regardless of whether or not the magnetron is energized, and can be measured extremely accurately. Similarly, the results of product temperature measurements obtained using other measurement methods are shown, but the measurement method using thermolabels and glycine-glucose solutions does not cause discoloration or browning unless the temperature reaches a certain level, and when cooled, It can be seen that while it is not clear what state the temperature-time relationship is in, it is clear that the method of the present invention can accurately grasp each point. Table 2 shows the results of the sterilization state and finished quality when the product temperature at the center of the package was measured using the method of the present invention, and when microwave treatment was performed with the same degree of sterilization using other methods. As a result, it can be seen that the packaged food whose temperature was measured by the method of the present invention has been sterilized well and is of good quality because it has not undergone excessive thermal history. However, the quality of packaged foods deteriorates due to deterioration and excessive heating, and the method of the present invention is extremely effective in sterilizing packaged foods at temperatures of 100°C or higher using microwave heating as the main heat source. It shows.
【表】
(f) 変敗袋数
(g) 試験袋数
実施例 1
合いびき肉200g、玉ねぎ50g、生パン粉20g
をよく混合して14mm厚みの生ハンバーグを作り、
フライパンで両面がきつね色になるまで焼いた。
このハンバーグにクロストリデユーム、スポロゲ
ナスNCA―pA―3679の耐熱性を有する芽胞を
103/gとなるよう注射器にてハンバーグ中心部
に接種した。この接種ハンバーグを透明なレトル
トパウチ(東洋製缶(株)製、ポリエステル×ポリプ
ロピレン、130×170mm)に充填し、回分式の空気
加圧式マイクロ波殺菌装置(東洋製缶製、型式
H40―C―40M/W)出力800W、周波数2450M
Hz、蒸気―熱水併用型)を使用し、空気加圧1.5
Kg/cm2圧力下でマイクロ波加熱を行つた。測温に
は、米国Luxtron社製測温器1000A型を使用し
た。センサー部のパウチへの装てんは第2図の方
法に準じて行つた。
マイクロ波を5分間照射し、次いで冷媒中へ4
分間浸漬したところ、最高到達温度が125℃とな
る良好な温度―時間曲線が得られた。この曲線を
もとに積分値(F)を算出したところF=3.2を得た。
芽胞接種サンプル20袋を50℃、2ケ月間恒温室に
保持したが何れも変敗しなかつた。[Table] (f) Number of lost bags
(g) Example of number of test bags 1 Minced meat 200g, onion 50g, raw breadcrumbs 20g
Mix well and make a 14mm thick raw hamburger steak.
Fry in a frying pan until both sides are golden brown.
Heat-resistant spores of Clostridium and Sporogenus NCA-pA-3679 are added to this hamburger.
It was inoculated into the center of the hamburger using a syringe at a concentration of 10 3 /g. This inoculated hamburger steak was filled into a transparent retort pouch (manufactured by Toyo Seikan Co., Ltd., polyester x polypropylene, 130 x 170 mm), and the batch air pressurized microwave sterilizer (manufactured by Toyo Seikan Co., Ltd., model
H40-C-40M/W) Output 800W, frequency 2450M
Hz, steam-hot water combination type), air pressurization 1.5
Microwave heating was carried out under Kg/cm 2 pressure. For temperature measurements, a 1000A thermometer manufactured by Luxtron in the United States was used. The sensor part was loaded into the pouch according to the method shown in Figure 2. Microwave irradiation for 5 minutes, then put into the refrigerant for 4 minutes.
When immersed for a minute, a good temperature-time curve was obtained with a maximum temperature of 125°C. When the integral value (F) was calculated based on this curve, F=3.2 was obtained.
Twenty bags of spore-inoculated samples were kept in a constant temperature room at 50°C for two months, but none of them deteriorated.
【表】
本実施例におけるF値の算出例を下記第3表に
示した。
実施例 2
ポテトダイス20%、ポテトマツシユ50%、タマ
ネギ10%、ニンジン12%、コーン8%の割合で混
合、調整したポテトサラダに103個/gとなるよ
う、バチルス・ズブチリスの芽胞(Fo=3.0)を
添加した。この芽胞接種サラダを透明な成型容器
(東洋製缶(株)製、商品名ラミコンカツプ、ポリプ
ロピレン×エバール×ポリプロピレン)に100g
宛を充填し、同じ構成の蓋をヒートシールして密
封した。測温には米国Luxtron社製測温器1000A
型を使用した。センサー部の容器への固定はテフ
ロン製グランド・パツキンで固定した。実施例1
で使用したと同じ空気加圧式マイクロ波加熱装置
を使用し、2.5Kg/cm2圧力下で5.5分間加熱し、次
いで冷却水により5分間冷却した。測温は最高到
達温度126℃を頂点とした山型の正確な温度―時
間曲線が得られた。この温度―時間曲線から積分
値Fを計算したところF=3.1となつた。
マイクロ波加熱した試料17袋を37℃、2ケ月間
恒温室に保持したが何れも変敗しなかつた。
実施例 3
市敗の粉末スープ(味の素製コーンスープ)を
所定量の水で溶解したものにクロストリデユー
ム、スポロゲナスの芽胞を103/gとなるよう接
種(Fo=2.8)したもの170gを内面にポリエチレ
ンをラミネートした紙カツプ(東缶興業製、商品
名PCカツプ)に充填、同構成の蓋をヒートシー
ルした。
測温方法は実施例2に準じて行つた。前述した
空気加圧式マイクロ波加熱装置により、マイクロ
波照射4分、次いで−5℃の冷風によつて10分間
冷却した測定された品温は極めて良好であり、こ
の条件はF=2.9であつた。加熱殺菌済包装食品
25個を37℃で1.5ケ月貯蔵したところいずれも変
敗しなかつた。[Table] An example of calculating the F value in this example is shown in Table 3 below. Example 2 Bacillus subtilis spores (Fo = 103 /g) were added to a potato salad prepared by mixing 20% potato dice, 50% potato mash, 10% onion, 12% carrot, and 8% corn. 3.0) was added. 100g of this spore-inoculated salad was placed in a transparent molded container (manufactured by Toyo Seikan Co., Ltd., trade name: Lamicon Cup, polypropylene x EVAL x polypropylene).
The container was filled and a lid of the same configuration was heat-sealed and sealed. For temperature measurement, we used a 1000A thermometer made by Luxtron in the United States.
I used a mold. The sensor part was fixed to the container using Teflon gland packing. Example 1
Using the same air-pressurized microwave heating device as used in , heating was performed under 2.5 Kg/cm 2 pressure for 5.5 minutes, followed by cooling with cooling water for 5 minutes. The temperature measurement yielded an accurate mountain-shaped temperature-time curve with the peak reached at 126°C. When the integral value F was calculated from this temperature-time curve, it was found to be F=3.1. Seventeen bags of microwave-heated samples were kept in a constant temperature room at 37°C for two months, but none of them deteriorated. Example 3 170 g of powdered soup (corn soup made by Ajinomoto) dissolved in a predetermined amount of water was inoculated with Clostridium and Sporogenus spores at a concentration of 10 3 /g (Fo = 2.8). A paper cup (manufactured by Tokan Kogyo Co., Ltd., trade name: PC Cup) laminated with polyethylene was filled, and a lid of the same composition was heat-sealed. The temperature measurement method was carried out in accordance with Example 2. Using the air pressurized microwave heating device described above, the product was irradiated with microwaves for 4 minutes and then cooled with cold air at -5°C for 10 minutes.The measured product temperature was extremely good, and this condition was F = 2.9. . Heat sterilized packaged food
When 25 pieces were stored at 37°C for 1.5 months, none of them deteriorated.
第1図は剛性容器への温度センサー取付状態を
示す断面図、第2図は柔軟容器への温度センサー
取付状態を示す断面図、第3図は熱電対を用いて
検出される温度とマイクロ波照射時間との関係を
示す線図である。
1,1aは容器、2はパツキング・グラウン
ド、3はプローブ、4は螢光体温度センサー、5
はプローブホルダーを夫々示す。
Figure 1 is a sectional view showing how the temperature sensor is attached to a rigid container, Figure 2 is a sectional view showing how the temperature sensor is attached to a flexible container, and Figure 3 is a diagram showing the temperature detected using a thermocouple and microwaves. FIG. 3 is a diagram showing the relationship with irradiation time. 1, 1a is a container, 2 is a packing ground, 3 is a probe, 4 is a fluorescent temperature sensor, 5
indicate probe holders, respectively.
Claims (1)
被殺菌物品を充填してなる密封包装体にマイクロ
波を照射し、マイクロ波照射下にある密封包装体
の温度の時間的経過を、蛍光体温度センサーを用
いて、蛍光体の蛍光波長領域での強度の温度依存
性に基づいて測定し、該蛍光体センサーで測定さ
れる温度が100℃以上となり、且つ式 F=∫t plog-1(T−121.1/Z)dt …(1) 式中、log-1はアンチログの意味であり、Tは
蛍光体センサーで測定される温度(℃)を表わ
し、tはマイクロ波照射開始後の時間(分)を表
わし、Zは微生物の温度依存性値、所謂Z値
(℃)である、 で表わされる積分値(F)が3.2以上となるに十分な
時間マイクロ波の照射を続けることを特徴とする
密封包装体の殺菌方法。 2 密封体に取付けた蛍光体温度センサーと紫外
線光源及び蛍光検出機構とを夫々光フアイバーか
ら成るプローブで接続し、蛍光体をプローブを介
して紫外線で照射し、発生する蛍光の強度をプロ
ーブを介して蛍光検出機構で検出することによ
り、温度を測定する特許請求の範囲第1項記載の
方法。[Claims] 1. Irradiating microwaves to a sealed package formed by filling an article to be sterilized in a container that is transparent to microwaves, and determining the temperature of the sealed package under microwave irradiation for a period of time. The process is measured using a phosphor temperature sensor based on the temperature dependence of the intensity in the fluorescence wavelength region of the phosphor, and the temperature measured by the phosphor sensor is 100°C or higher, and the formula F= ∫ t p log -1 (T-121.1/Z) dt ...(1) In the formula, log -1 means antilog, T represents the temperature (℃) measured by the phosphor sensor, and t It represents the time (minutes) after the start of microwave irradiation, and Z is the temperature dependence value of microorganisms, the so-called Z value (℃). A method for sterilizing a sealed package, characterized by continuing irradiation with. 2 Connect the phosphor temperature sensor attached to the sealed body to the ultraviolet light source and the fluorescence detection mechanism with probes made of optical fibers, irradiate the phosphor with ultraviolet light through the probe, and measure the intensity of the generated fluorescence through the probe. 2. The method according to claim 1, wherein the temperature is measured by detecting the temperature using a fluorescence detection mechanism.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP9603281A JPS581627A (en) | 1981-06-23 | 1981-06-23 | Method of sterilizing sealed package |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP9603281A JPS581627A (en) | 1981-06-23 | 1981-06-23 | Method of sterilizing sealed package |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS581627A JPS581627A (en) | 1983-01-07 |
JPS6339225B2 true JPS6339225B2 (en) | 1988-08-04 |
Family
ID=14154078
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP9603281A Granted JPS581627A (en) | 1981-06-23 | 1981-06-23 | Method of sterilizing sealed package |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS581627A (en) |
Cited By (1)
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JP2010038675A (en) * | 2008-08-04 | 2010-02-18 | Toyo Seikan Kaisha Ltd | Method for measuring temperature of pouched fluid food and temperature measuring jig |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS62186774A (en) * | 1986-02-08 | 1987-08-15 | Nichirei:Kk | Thermal sterilization of food packed in sealed container and treating apparatus therefor |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2010038675A (en) * | 2008-08-04 | 2010-02-18 | Toyo Seikan Kaisha Ltd | Method for measuring temperature of pouched fluid food and temperature measuring jig |
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JPS581627A (en) | 1983-01-07 |
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