JP4290458B2

JP4290458B2 - Method for producing germinated brown rice

Info

Publication number: JP4290458B2
Application number: JP2003096822A
Authority: JP
Inventors: 博志行光; 茂東井; 雅弘河野
Original assignee: SCIENCE Tech INTERACT Co Ltd
Current assignee: SCIENCE Tech INTERACT Co Ltd
Priority date: 2003-03-31
Filing date: 2003-03-31
Publication date: 2009-07-08
Anticipated expiration: 2023-03-31
Also published as: JP2004298124A

Description

【０００１】
【発明の属する技術分野】
本発明は、抗酸化能の高い発芽玄米の製造方法、及び、これにより製造された抗酸化能の高い発芽玄米に関する。
【０００２】
【従来の技術】
玄米を発芽させた発芽玄米は、通常の玄米と比べて炊飯しやすく、消化吸収が良く、ビタミンE、フィチン酸、フェラル酸等の抗酸化物質や、γ−アミノ酪酸などの栄養成分が多く含まれることから、機能性食品として評価されている。
【０００３】
発芽玄米は、玄米を水中に浸漬して吸水させて発芽させることで製造されるが、従来、この発芽処理中や処理後に、細菌の増殖や、発酵臭等の異臭が発生するという問題があった。また、玄米を吸水させるために水に浸漬する時間が長いと、玄米に含まれる貴重な栄養分が流出するという問題もあった。
【０００４】
特許文献１には、玄米を水に浸漬して吸水させ、発芽させた後、９８〜１８０℃程度の高温で湿熱処理、８０℃以上で乾燥処理等を行って、特定の吸水率およびアルファ化を有する発芽玄米を製造する方法が記載されている。しかしながら、この方法では、発芽処理後に高温で湿熱、乾燥処理を行うため、玄米の抗酸化能が低下するという問題がある。さらに、この方法による発芽玄米は、含有でんぷんの５〜５０％がアルファ化されているため食味も低下する。
【０００５】
特許文献２には、玄米を、溶存酸素が２０ｐｐｍ以上の水に９０〜１２０時間浸漬し、５０〜５７℃で乾燥してγ−アミノ酪酸を富化した発芽玄米を製造する方法が記載されている。しかし、この方法による場合には、γ−アミノ酪酸は富化されるものの浸漬時間が長く、玄米の含有する他の栄養素が流出する恐れがあった。
【０００６】
【従来技術】
【特許文献１】
特開２００２−１５９２６９号公報
【特許文献２】
特開２０００−３００１９６号公報
【０００７】
【発明が解決しようとする課題】
本発明は、これらの従来技術では達成が困難であった、浸漬の長時間化、玄米の抗酸化能の低下、細菌の増殖、異臭の発生、更には食味の低下等の問題を解決できる発芽玄米の新規な製造方法の提供を目的とする。
【０００８】
【課題を解決するための手段】
本発明者は、上記の目的を達成すべく研究を重ねたところ、短時間で発芽させることが可能で、細菌の繁殖や異臭の発生がなく、玄米の抗酸化能を向上させる最適な浸漬水の条件、及び、抗酸化能の低下を防止できる乾燥条件を見出した。その結果、製造された発芽玄米は高い抗酸化性を有し、含有でんぷんのアルファ化に変化がないため発芽玄米単独で食しても味が低下しないなどの従来技術の有していた問題を解決できる発芽玄米の新規な製造方法を開発した。すなわち、本発明は、下記の特徴を有する発芽玄米の製造方法にある。
（１）玄米に吸水させて発芽させる工程、及び、発芽した玄米を乾燥する工程を少なくとも有する発芽玄米の製造方法であって、発芽工程において、ｐＨが２〜４、温度が１５〜３５℃、溶存酸素濃度が４ｐｐｍ以上の水に玄米を浸漬して吸水させ、乾燥工程においては、２５℃以下の空気を送風して発芽玄米を乾燥させることを特徴とする発芽玄米の製造方法。
（２）玄米を洗米し、次いでｐＨ２〜３．５の酸性水を玄米に吸水させて発芽させる上記（１）に記載の発芽玄米の製造方法。
（３）発芽した玄米をｐＨ２〜３．５の酸性水にて殺菌し、次いで乾燥させる上記（１）又は（２）に記載の発芽玄米の製造方法。
（４）乾燥工程において送風する空気の温度が２０℃以下である上記（１）〜（３）いずれかに記載の発芽玄米の製造方法。
（５）発芽工程において、玄米を浸漬している水の一部を細かい粒状にして水面上に供給しながら該浸漬水を循環する、及び／又は、該浸漬水中に直接空気を送り込みながら循環することにより、該浸漬水の溶存酸素濃度を４ｐｐｍ以上に保つ上記（１）〜（４）のいずれかに記載の発芽玄米の製造方法。
（６）洗米する前の玄米の水分含有率を１０％とすると、発芽工程において、浸漬開始後、玄米の水分含有率が２０〜２８％となった時点で１回だけ水を入れ替える上記（１）〜（５）のいずれかに記載の発芽玄米の製造方法。
【０００９】
【発明の実施の形態】
本発明の製造方法において発芽させる玄米は、好ましくは洗米し、玄米に付着している汚れや雑菌を除去するために行う。洗米に使用する水としては、水道水、天然水、強酸性電解水を含むｐH２〜３．５の酸性水、強アルカリ性電解水、強酸性電解水と強アルカリ性電解水とを混ぜ合わせた中和水、あるいは、これらのうち２種以上を組み合わせたものが使用できる。特に、菌の増殖を抑制しながら発芽を促進するという理由で、強酸性電解水などのｐH２〜３．５の酸性水を使用するのが好ましい。洗米時間は、洗米方法、玄米の状態、量などにより決定される。
【００１０】
洗米後の玄米の水分含有率は、原料玄米の水分含有率を１０％としたとき、好ましくは約１３〜１７％、特に好ましくは約１４〜１６％程度であるのが好適である。なお、水分含有率は赤外線水分計を使用して測定した値である。
【００１１】
次いで、洗米した玄米の発芽工程に入るが、洗米後の玄米は、玄米がこぼれ落ちない程度の穴を多数有する容器にいれておき、この容器ごと浸漬槽にいれるのが好ましい。
【００１２】
本発明の発芽工程において、洗米した玄米を浸漬して吸水させる浸漬水は、ｐHが２〜４、温度が１５〜３５℃、溶存酸素濃度が４ｐｐｍ以上の水である。浸漬水のｐHが２〜４の範囲内であれば、高い発芽率が得られ、また、発芽玄米の抗酸化能（特にヒドロキシラジカル（HO・）の消去率）を向上させることが可能となる。特に、ｐHは２．５〜３．５であると、発芽率が高くなり好ましい。
【００１３】
浸漬水の種類としては、かかるｐHの範囲であれば、特に限定されないが、例えば、強酸性電解水や塩酸を希釈した酸性水などが、好ましい例として挙げられる。
【００１４】
浸漬水の温度は、１５〜３５℃である必要がある。３５℃を超えると、細菌の増殖や発酵臭等の異臭が発生しやすくなり、また、１５℃未満では、玄米の発芽率が大きく低下するためである。浸漬水の温度は、２５〜３５℃であると、発芽率が最も高くなるので好ましい。
【００１５】
本発明で浸漬水の溶存酸素は重要であり、溶存酸素量は４ｐｐｍ以上が必要である。溶存酸素量が４ｐｐｍ未満では玄米の発芽率が大きく低下するためである。溶存酸素濃度は、さらに、４ｐｐｍ以上、特に、６ｐｐｍ以上が高い発芽率を得るために好ましい。
【００１６】
発芽工程において、浸漬水の溶存酸素濃度を上記の範囲に保つため、浸漬している水の一部を細かい粒状にして水面上に供給しながら該浸漬水を循環する、及び／又は、該浸漬水中に直接空気を送り込みながら循環することが好ましい。後者の場合、浸漬水の入った浸漬槽の底から空気を送り込むと、浸漬水中に効率良く酸素が溶け込むため、好ましい。
【００１７】
浸漬水は、発芽工程中に１〜２回、入れ替えてもよい。特に、洗米する前の玄米の水分含有率を１０％とすると、発芽工程において、浸漬開始後、玄米の水分含有率が２０〜２８％となった時点（浸漬開始後およそ５〜７時間後であることが多い）で１回だけ水を入れ替えるのが、高い発芽率を得るために最も好ましい。発芽工程中、玄米は、かかる浸漬水の入れ替え時以外は、連続して浸漬状態にするのが、高い発芽率を得る上で好ましい。
【００１８】
発芽工程における浸漬時間は、浸漬水の種類、ｐH値、温度、溶存酸素濃度、浸漬水の入れ替え条件、その他の要因により決まり、一概には決定できないが、およそ１８〜２３時間程度で、玄米のおよそ７０％が発芽する。本発明において、「発芽」とは、胚芽部分が膨れ、胚芽に切れ目ができた状態、又は、胚芽から芽が１．０ｍｍ以下突出している状態のどちらかを意味する。
【００１９】
発芽工程の後、５０℃以下の空気を送風して発芽玄米を乾燥させる。乾燥工程において送風する空気の温度を５０℃以下とするのは、５０℃を超えると、発芽玄米の抗酸化能が大幅に低下するためである。送風する空気の温度は、２５℃以下であると、抗酸化能の低下を最小限にすることが可能となるので、特に好ましい。一方、送風する空気の温度が過度に大きいと胴割れの原因になるので２０℃以下であるのが好ましい。
【００２０】
本発明において、発芽玄米の抗酸化能は、生体障害に関与するスーパーオキシド（O₂ ^・ ^-）及びヒドロキシルラジカル（HO・）の消去率、また、脂質の過酸化抑制率の値によって評価した。
【００２１】
本発明の発芽工程の後、乾燥工程の前に、好ましくは、殺菌工程、及び／又は洗米工程が設けられる。
【００２２】
殺菌工程は、発芽工程に引き続き、殺菌及び／または除菌を目的としておこなう。発芽が完了（玄米のおよそ７０％以上が発芽した状態）した段階（発芽工程の条件にもよるが、洗米開始からおよそ１８時間以上経過後）で、浸漬槽内の水をｐH２．０〜３．５の酸性水に入れ替え、発芽玄米を浸漬した状態で、空気を送り込みながら循環させるのが好ましい。殺菌工程には、およそ１０分程度の時間が適当である。
【００２３】
また、洗米工程は、発芽工程後、又は殺菌工程後、発芽玄米に付着している汚れや雑菌を除去するために行う。洗米には、水道水、強アルカリ性電解水、強酸性電解水と強アルカリ性電解水を混ぜ合わせた中和水などを使用する方法、あるいは、この３種類のうち２種以上を組み合わせた方法を使用するのが好ましい。洗米は、複数回行っても良く、洗米時間、洗米回数は、発芽玄米の状態、量などにもよるが、代表的な例としては、水道水で、１５〜３０分間の洗米を好ましくは１度だけ行う方法が挙げられる。
【００２４】
乾燥工程の後、発芽玄米を真空包装し、殺菌処理を行うのが好ましい。殺菌処理は、食品衛生法で定められたガイドライン内の菌数に収めるために行うものであり、加熱・冷却処理法等が好適な方法として挙げられる。
【００２５】
【実施例】
以下に実施例により本発明を具体的に説明するが、本発明はこれらの実施例に限定されないことはもちろんである。例１，３，４，５，７，８，１１〜１３，１６〜２０は実施例、例２，６，１０，１４，１５は比較例である。
【００２６】
玄米及び発芽玄米のスーパーオキシド（O₂ ^・ ^-）の消去率、ヒドロキシルラジカル（HO・）の消去率、及び、脂質の過酸化抑制率は、以下のようにして測定した。
・スーパーオキシド（O₂ ^・ ^-）の消去率の測定方法：
ＤＭＰＯスピントラッピング剤を用いるＥＳＲ測定により、常法に従った測定方法。スーパーオキシド（O₂ ^・ ^-）の発生系としては、キサンチンオキシダーゼを用いてキサンチン−ヒポキサンチンの系を用いた。
・ヒドロキシルラジカル（HO・）の消去率の測定方法：
ＤＭＰＯスピントラッピング剤を用いるＥＳＲ測定により、常法に従った測定方法。ヒドロキシルラジカル（HO・）の発生系としては、フェントン反応系を用いた。
・脂質の過酸化抑制率の測定方法：
脂質としてはリノレン酸（関東化学・東京）を用いた。各々の希釈試料溶液共存下でリノレン酸の自動酸化による過酸化反応の測定を行った。生成した脂質過酸化物、主にマロンジアルデヒド、とチオバルビーツール酸との赤色反応生成物を波長５３２ｎｍで測定。
【００２７】
［例１］
原料玄米（新潟県産コシヒカリ）を、水道水を用いて洗米し、ネット付きトレイ（ネットの穴は玄米がこぼれ落ちない程度で、均一化されている）に入れた。洗米後の玄米の水分含有率は、原料玄米の水分含有率を１０％としたとき、約１５％であった。
【００２８】
次いで、強酸性電解水からなる、ｐＨ２．６、温度が２８℃、溶存酸素濃度が８ｐｐｍの浸漬水が入った浸漬槽に、トレイごと洗米後の玄米を浸漬し、発芽させた。発芽工程中、浸漬水の一部を細かい粒状にして水面上に供給し、かつ、浸漬水中に浸漬槽の底から直接空気を送り込みながら循環させ、浸漬開始時と同じ状態に保った。
【００２９】
浸漬開始後、７時間が経過し、玄米の水分含有率がおよそ２７％になった時点で、一度、浸漬槽内の水を入れ替えた。新しい浸漬水は、入れ替え前と同様のｐＨ，温度、溶存酸素濃度であり、その後も同様の状態に保った。洗米開始後、２１時間経過したときの玄米の発芽率を表１に示す。
【００３０】
［例２〜５］（浸漬水のｐＨ値の影響）
浸漬水のｐＨを１．２（例２）、２．０(例３)、３．０(例４)、４．０(例５)とした以外は例１と同様にして、玄米を発芽させた。浸漬開始後、玄米の水分含有率がおよそ２７％になった時点で、一度、浸漬水を入れ替えた。浸漬開始後、２１時間経過したときの玄米の発芽率を表１に示す。
【００３１】
［例６〜９］（浸漬水の温度の影響）
浸漬水の温度を５℃（例６）、２５℃（例７）、３０℃（例８）、３５℃（例９）とした以外は例１と同様にして、玄米を発芽させた。浸漬開始後、玄米の水分含有率がおよそ２７％になった時点で、一度、浸漬水を入れ替えた。洗米開始後、２１時間経過したときの玄米の発芽率を表１に示す。例９においては、発芽工程において、異臭（発酵臭）が発生した。
【００３２】
［例１０］（浸漬水の溶存酸素濃度の影響）
浸漬水の溶存酸素濃度を３ｐｐｍに保った以外は例１と同様にして、玄米を発芽させた。浸漬開始後、玄米の水分含有率がおよそ２７％になった時点で、一度、浸漬水を入れ替えた。洗米開始後、２１時間経過したときの玄米の発芽率を表１に示す。
【００３３】
［例１１］（浸漬水の溶存酸素濃度の影響）
浸漬水の一部を細かい粒状にして水面上に供給しながら循環させ、浸漬水の溶存酸素濃度を４ｐｐｍに保った以外は例１と同様にして、玄米を発芽させた。浸漬開始後、玄米の水分含有率がおよそ２７％になった時点で、一度、浸漬水を入れ替えた。洗米開始後、２１時間経過したときの玄米の発芽率を表１に示す。
【００３４】
［例１２］（浸漬水の溶存酸素濃度の影響）
浸漬水中に浸漬槽の底から直接空気を送り込みながら循環させ、浸漬水の溶存酸素濃度を５ｐｐｍに保った以外は例１と同様にして、玄米を発芽させた。浸漬開始後、玄米の水分含有率がおよそ２７％になった時点で、一度、浸漬水を入れ替えた。洗米開始後、２１時間経過したときの玄米の発芽率を表１に示す。
【００３５】
［例１３〜１５］（浸漬水の種類）
浸漬水を、ｐＨ２．６、温度が２８℃、溶存酸素濃度が８ｐｐｍの塩酸（例１３）、ｐＨ７．９、温度が２８℃の水道水（例１４）、ｐＨ１１．４、温度が２８℃の強アルカリ性電解水(例１５)とした以外は、例１と同様にして、玄米を発芽させた。浸漬開始後、玄米の水分含有率がおよそ２７％になった時点で、一度、浸漬水を入れ替えた。洗米開始後、２１時間経過したときの玄米の発芽率を表１に示す。
【００３６】
［例１６〜１７］（浸漬水の入れ替え）
浸漬水を、玄米の水分含有率がおよそ２３％になった時点（浸漬開始後およそ３時間後）に一度入れ替えた（例１６）、玄米の水分含有率がおよそ２３％になった時点（浸漬開始後およそ３時間後）及びおよそ２７％になった時点（浸漬開始後およそ７時間後）の二回入れ替えた（例１７）こと以外は例１と同様にして、玄米を発芽させた。洗米開始後、２１時間経過したときの玄米の発芽率を表１に示す。
【００３７】
［例１８］（浸漬と無浸漬の組み合わせ）
浸漬状態を７時間、及び無浸漬状態（浸漬水と同様の水を連続的に玄米にかけた）１６時間の計２３時間で吸水させたこと以外は、例１と同様にして、玄米を発芽させた。洗米開始後、２３時間経過したときの玄米の発芽率を表１に示す。
【００３８】
【表１】

【００３９】
［例１９］
例１で得られた発芽玄米の抗酸化能をスーパーオキシド（O₂ ^・ ^-）及びヒドロキシルラジカル（HO・）の消去率、脂質の過酸化抑制率の値によって評価した。これを市販品（Ａ社）の発芽玄米品とともに表２に示した。
【００４０】
【表２】

【００４１】
［例２０］
例１と同様にして玄米を発芽させ、浸漬開始後およそ２１時間経過したとき、浸漬水を、ｐH２．２の酸性水（温度２９℃）に入れ替え、空気を送り込みながら１０分間循環させ、殺菌を行った。
次いで、水道水を用いて、発芽玄米を洗米した。次に、２０℃の空気を送風して、発芽玄米を乾燥させた。乾燥時間は１６０分であった。
以上のようにして製造された発芽玄米のヒドロキシルラジカル（HO・）の消去率を表３に示す。
【００４２】
［例２１〜２２］（乾燥温度の影響）
乾燥工程における送風を、５０℃、１４分（例２１）、１００℃、４分（例２２）とした以外は、例１９と同様にして発芽玄米を製造した。製造された発芽玄米のヒドロキシルラジカル（HO・）の消去率を表３に示す。
【００４３】
【表３】

【００４４】
［例２３］（食感テスト）
上記の例１で得られた発芽玄米を白米と同様な炊き方（発芽玄米：４５０ｇ、炊飯水：５５０ｍｌの水道水、炊飯前の浸漬時間：６０分、電気炊飯器：松下電器社製炊飯器、ＩＨジャーＳＲ−Ｄ１０Ａ−Ｃ、炊飯時間：５２分、蒸らし時間：１０分）で炊飯し、その食感をテストした。また、市販品（Ａ社、Ｂ社、Ｃ社）の発芽玄米をそれぞれ同様な条件で炊飯した。得られた各炊飯米について、１０人の試験者によりそれぞれの持点を１点として、食感について、本発明の発芽玄米との比較を行った。
その結果は、表４に示されるようになり、本発明の発芽玄米の炊飯品は高い得点を有し、本発明の発芽玄米の食感が極めて優れていることが判明した。
【００４５】
【表４】

【００４６】
【発明の効果】
本発明によれば、細菌の増殖を抑えながら玄米を短時間で発芽させ、かつ抗酸化能の高い発芽玄米を得ることが可能となる。本発明により得られた発芽玄米は、米糠特有の臭いも少なく、栄養価や抗酸化能の高く、更に、それ単独で炊飯しても美味しく食することが可能な健康食品として多方面で利用できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing germinated brown rice having high antioxidant ability, and a germinated brown rice having high antioxidant ability produced thereby.
[0002]
[Prior art]
Germinated brown rice, which is germinated brown rice, is easier to cook than ordinary brown rice, has good digestion and absorption, and contains many antioxidants such as vitamin E, phytic acid, ferulic acid, and γ-aminobutyric acid. Therefore, it is evaluated as a functional food.
[0003]
Germinated brown rice is produced by immersing brown rice in water and allowing it to absorb water and germinate. Conventionally, there has been a problem that abnormal odors such as bacterial growth and fermentation odor are generated during and after the germination treatment. It was. Moreover, if the time for immersing brown rice in water to absorb water is long, there is a problem that precious nutrients contained in the brown rice flow out.
[0004]
In Patent Document 1, after brown rice is soaked in water and allowed to absorb and germinate, wet heat treatment is performed at a high temperature of about 98 to 180 ° C., drying treatment is performed at 80 ° C. or higher, and the specific water absorption and pregelatinization are performed. A method for producing germinating brown rice having the following is described. However, this method has a problem in that the antioxidant ability of brown rice is lowered because wet heat and drying are performed at a high temperature after the germination treatment. Furthermore, the germinated brown rice produced by this method has a reduced taste because 5 to 50% of the contained starch is pregelatinized.
[0005]
Patent Document 2 describes a method for producing germinated brown rice in which brown rice is immersed in water having dissolved oxygen of 20 ppm or more for 90 to 120 hours and dried at 50 to 57 ° C. to enrich γ-aminobutyric acid. Yes. However, according to this method, although γ-aminobutyric acid is enriched, the soaking time is long and other nutrients contained in brown rice may flow out.
[0006]
[Prior art]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-159269 [Patent Document 2]
Japanese Patent Laid-Open No. 2000-300196
[Problems to be solved by the invention]
The present invention is a germination capable of solving problems such as prolonged soaking, reduced antioxidant capacity of brown rice, bacterial growth, generation of off-flavor, and further deterioration of taste, which are difficult to achieve with these conventional techniques. The purpose is to provide a new method for producing brown rice.
[0008]
[Means for Solving the Problems]
The present inventor has conducted research to achieve the above-mentioned object, and as a result, it is possible to germinate in a short time, there is no bacterial growth or generation of off-flavor, and optimal immersion water that improves the antioxidant capacity of brown rice. And a drying condition capable of preventing a decrease in antioxidant capacity. As a result, the germinated brown rice produced has high antioxidant properties, and there is no change in the pregelatinization of the starch. A new production method for germinating brown rice was developed. That is, this invention exists in the manufacturing method of the germination brown rice which has the following characteristics.
(1) A method for producing germinated brown rice having at least a step of allowing brown rice to absorb water and germinating, and a step of drying the germinated brown rice, wherein in the germination step, pH is 2 to 4, temperature is 15 to 35 ° C, A method for producing germinated brown rice, characterized in that brown rice is immersed in water having a dissolved oxygen concentration of 4 ppm or more to absorb water, and in the drying step, germinated brown rice is dried by blowing air at 25 ° C. or lower.
(2) The method for producing germinated brown rice according to the above (1), wherein the brown rice is washed and then the acidic water having a pH of 2 to 3.5 is absorbed into the brown rice and germinated.
(3) The method for producing germinated brown rice according to (1) or (2), wherein germinated brown rice is sterilized with acidic water having a pH of 2 to 3.5 and then dried.
(4) The manufacturing method of the germinated brown rice in any one of said (1)-(3) whose temperature of the air ventilated in a drying process is 20 degrees C or less.
(5) In the germination step, circulate the immersion water while finely granulating a part of the water in which brown rice is immersed and / or supplying air onto the water surface and / or circulating the air directly into the immersion water. The manufacturing method of the germinated brown rice in any one of said (1)-(4) which keeps the dissolved oxygen concentration of this immersion water at 4 ppm or more.
(6) Assuming that the moisture content of brown rice before washing is 10%, in the germination step, after the start of soaking, when the moisture content of brown rice becomes 20 to 28%, the water is replaced only once (1 ) production how of germinated brown rice according to any one of the - (5).
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The brown rice to be germinated in the production method of the present invention is preferably washed to remove dirt and germs adhering to the brown rice. The water used for washing the rice is tap water, natural water, acidic water having a pH of 2 to 3.5 including strongly acidic electrolyzed water, strongly alkaline electrolyzed water, neutralized by mixing strongly acidic electrolyzed water and strongly alkaline electrolyzed water. Water or a combination of two or more of these can be used. In particular, it is preferable to use acidic water having a pH of 2 to 3.5 such as strongly acidic electrolyzed water because it promotes germination while suppressing the growth of bacteria. The rice washing time is determined by the rice washing method, the state and amount of brown rice, and the like.
[0010]
The water content of the brown rice after washing is preferably about 13 to 17%, particularly preferably about 14 to 16%, when the water content of the raw brown rice is 10%. The moisture content is a value measured using an infrared moisture meter.
[0011]
Next, the washed rice is put into a germination process. After washing, the brown rice is preferably placed in a container having many holes so that the brown rice does not spill out, and this container is preferably placed in the immersion tank.
[0012]
In the germination step of the present invention, the immersion water for immersing and absorbing the washed brown rice is water having a pH of 2 to 4, a temperature of 15 to 35 ° C., and a dissolved oxygen concentration of 4 ppm or more. If the pH of the immersion water is in the range of 2 to 4, a high germination rate can be obtained, and the antioxidant ability of germinated brown rice (particularly, the hydroxy radical (HO ·) elimination rate) can be improved. . In particular, the pH is preferably from 2.5 to 3.5 because the germination rate is increased.
[0013]
Although it will not specifically limit if it is the range of this pH as immersion water kind, For example, the acidic water etc. which diluted strong acidic electrolyzed water and hydrochloric acid are mentioned as a preferable example.
[0014]
The temperature of immersion water needs to be 15-35 degreeC. If the temperature exceeds 35 ° C., a strange odor such as bacterial growth and fermentation odor is likely to occur, and if it is less than 15 ° C., the germination rate of brown rice is greatly reduced. The temperature of the immersion water is preferably 25 to 35 ° C. because the germination rate is the highest.
[0015]
In the present invention, the dissolved oxygen in the immersion water is important, and the amount of dissolved oxygen is required to be 4 ppm or more. This is because if the amount of dissolved oxygen is less than 4 ppm, the germination rate of brown rice is greatly reduced. The dissolved oxygen concentration is preferably 4 ppm or more, particularly 6 ppm or more in order to obtain a high germination rate.
[0016]
In the germination step, in order to keep the dissolved oxygen concentration of the immersion water within the above range, the immersion water is circulated while supplying a part of the immersion water in a fine granular form on the water surface, and / or the immersion It is preferable to circulate while sending air directly into the water. In the latter case, it is preferable to send air from the bottom of the immersion tank containing immersion water because oxygen is efficiently dissolved in the immersion water.
[0017]
The immersion water may be changed once or twice during the germination process. In particular, if the moisture content of brown rice before washing is 10%, in the germination step, the time when the moisture content of brown rice becomes 20 to 28% after the start of immersion (after about 5 to 7 hours after the start of immersion). It is most preferable to change the water only once in order to obtain a high germination rate. During the germination process, it is preferable that brown rice is continuously dipped in order to obtain a high germination rate except when the immersion water is replaced.
[0018]
The soaking time in the germination process is determined by the type of soaking water, pH value, temperature, dissolved oxygen concentration, replacement conditions of soaking water, and other factors, and cannot be determined unconditionally, but is approximately 18 to 23 hours. Approximately 70% germinate. In the present invention, “germination” means either a state in which the germ portion is swollen and a cut is formed in the germ, or a state in which the bud protrudes from the embryo by 1.0 mm or less.
[0019]
After the germination step, air of 50 ° C. or lower is blown to dry the germinated brown rice. The reason why the temperature of the air blown in the drying step is 50 ° C. or less is that when it exceeds 50 ° C., the antioxidant ability of the germinated brown rice is significantly reduced. It is particularly preferable that the temperature of the air to be blown is 25 ° C. or lower, since it is possible to minimize the decrease in the antioxidant capacity. On the other hand, if the temperature of the air to be blown is excessively high, it will cause a body crack, and therefore it is preferably 20 ° C. or lower.
[0020]
In the present invention, the antioxidant ability of germinated brown rice was evaluated based on the elimination rate of superoxide (O ₂ ^· ⁻ ) and hydroxyl radical (HO ·) involved in biological damage, and the value of lipid peroxidation inhibition rate.
[0021]
After the germination step of the present invention, preferably before the drying step, a sterilization step and / or a rice washing step is provided.
[0022]
The sterilization step is performed for the purpose of sterilization and / or sterilization following the germination step. When germination is completed (approximately 70% or more of brown rice has germinated) (depending on the conditions of the germination process, approximately 18 hours or more after the start of washing), the water in the immersion bath is adjusted to pH 2.0-3 It is preferable to circulate while sending air in the state where it is replaced with acidic water of .5 and the germinated brown rice is immersed. A time of about 10 minutes is appropriate for the sterilization process.
[0023]
Moreover, a rice washing process is performed in order to remove the stain | pollution | contamination and miscellaneous bacteria adhering to germination brown rice after a germination process or a sterilization process. Washing rice uses tap water, strong alkaline electrolyzed water, neutral water mixed with strong acidic electrolyzed water and strong alkaline electrolyzed water, or a combination of two or more of these three types. It is preferable to do this. Washing rice may be performed a plurality of times, and the washing time and the number of times of washing depend on the state and amount of germinated brown rice, but as a typical example, washing with tap water for 15 to 30 minutes is preferable. The method of performing only once.
[0024]
After the drying step, germinated brown rice is preferably vacuum-packed and sterilized. The sterilization treatment is performed in order to keep the number of bacteria within the guidelines defined by the Food Sanitation Law, and a heating / cooling treatment method or the like can be mentioned as a suitable method.
[0025]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Examples 1, 3, 4, 5, 7, 8, 11 to 13, and 16 to 20 are examples, and examples 2, 6, 10, 14, and 15 are comparative examples.
[0026]
Superoxide brown rice and brown rice (O ₂ ^· ^-) erasure rate, erasure rate of hydroxylation radical (HO ·), and, peroxidation inhibitory rate of lipids was measured as follows.
・ Measurement method of superoxide (O ₂ ^・ ^- ) elimination rate:
A measurement method according to a conventional method by ESR measurement using a DMPO spin trapping agent. As a superoxide (O ₂ ^· ⁻ ) generation system, xanthine oxidase was used and a xanthine-hypoxanthine system was used.
・ Measurement method of elimination rate of hydroxyl radical (HO ・):
A measurement method according to a conventional method by ESR measurement using a DMPO spin trapping agent. A Fenton reaction system was used as a hydroxyl radical (HO.) Generation system.
・ Measurement method of lipid peroxidation inhibition rate:
As the lipid, linolenic acid (Kanto Chemical, Tokyo) was used. In the presence of each diluted sample solution, the peroxidation reaction by the auto-oxidation of linolenic acid was measured. The red reaction product of the produced lipid peroxide, mainly malondialdehyde, and thiobarbie tururic acid was measured at a wavelength of 532 nm.
[0027]
[Example 1]
The raw brown rice (Koshihikari from Niigata Prefecture) was washed with tap water and placed in a tray with a net (the hole in the net is uniform so that the brown rice does not fall out). The water content of the brown rice after washing was about 15% when the water content of the raw brown rice was 10%.
[0028]
Next, the brown rice after washing with the tray was immersed in an immersion tank containing immersion water having a pH of 2.6, a temperature of 28 ° C., and a dissolved oxygen concentration of 8 ppm, which was made of strongly acidic electrolyzed water, and germinated. During the germination process, a part of the immersion water was finely granulated and supplied onto the water surface, and was circulated while sending air directly from the bottom of the immersion tank into the immersion water, and kept in the same state as at the start of immersion.
[0029]
Seven hours passed after the start of soaking, and when the moisture content of the brown rice reached approximately 27%, the water in the soaking tank was once replaced. The new immersion water had the same pH, temperature and dissolved oxygen concentration as before the replacement, and was kept in the same state thereafter. Table 1 shows the germination rate of brown rice when 21 hours have passed since the start of washing.
[0030]
[Examples 2 to 5] (Effect of pH value of immersion water)
Germination of brown rice in the same manner as in Example 1 except that the pH of the immersion water was 1.2 (Example 2), 2.0 (Example 3), 3.0 (Example 4), and 4.0 (Example 5). I let you. After the start of soaking, the soaking water was replaced once when the moisture content of the brown rice reached approximately 27%. Table 1 shows the germination rate of brown rice when 21 hours have passed since the start of the immersion.
[0031]
[Examples 6 to 9] (Influence of immersion water temperature)
Brown rice was germinated in the same manner as in Example 1 except that the temperature of the immersion water was 5 ° C. (Example 6), 25 ° C. (Example 7), 30 ° C. (Example 8), and 35 ° C. (Example 9). After the start of soaking, the soaking water was replaced once when the moisture content of the brown rice reached approximately 27%. Table 1 shows the germination rate of brown rice when 21 hours have passed since the start of washing. In Example 9, a strange odor (fermented odor) was generated in the germination process.
[0032]
[Example 10] (Influence of dissolved oxygen concentration of immersion water)
Brown rice was germinated in the same manner as in Example 1 except that the dissolved oxygen concentration of the immersion water was kept at 3 ppm. After the start of soaking, the soaking water was replaced once when the moisture content of the brown rice reached approximately 27%. Table 1 shows the germination rate of brown rice when 21 hours have passed since the start of washing.
[0033]
[Example 11] (Influence of dissolved oxygen concentration of immersion water)
Brown rice was germinated in the same manner as in Example 1 except that a part of the immersion water was made fine and circulated while being supplied onto the water surface, and the dissolved oxygen concentration of the immersion water was kept at 4 ppm. After the start of soaking, the soaking water was replaced once when the moisture content of the brown rice reached approximately 27%. Table 1 shows the germination rate of brown rice when 21 hours have passed since the start of washing.
[0034]
[Example 12] (Influence of dissolved oxygen concentration of immersion water)
Brown rice was germinated in the same manner as in Example 1 except that air was circulated in the immersion water while directly sending air from the bottom of the immersion tank, and the dissolved oxygen concentration in the immersion water was kept at 5 ppm. After the start of soaking, the soaking water was replaced once when the moisture content of the brown rice reached approximately 27%. Table 1 shows the germination rate of brown rice when 21 hours have passed since the start of washing.
[0035]
[Examples 13 to 15] (Type of immersion water)
Immersion water, pH 2.6, temperature 28 ° C, dissolved oxygen concentration 8 ppm hydrochloric acid (Example 13), pH 7.9, temperature 28 ° C tap water (Example 14), pH 11.4, temperature 28 ° C Brown rice was germinated in the same manner as in Example 1 except that strong alkaline electrolyzed water (Example 15) was used. After the start of soaking, the soaking water was replaced once when the moisture content of the brown rice reached approximately 27%. Table 1 shows the germination rate of brown rice when 21 hours have passed since the start of washing.
[0036]
[Examples 16 to 17] (Replacement of immersion water)
The immersion water was replaced once when the moisture content of brown rice became approximately 23% (approximately 3 hours after the start of immersion) (Example 16), when the moisture content of brown rice became approximately 23% (immersion) Brown rice was germinated in the same manner as in Example 1 except that it was replaced twice (about 17 hours after the start) and about 27% (about 17 hours after the start of soaking). Table 1 shows the germination rate of brown rice when 21 hours have passed since the start of washing.
[0037]
[Example 18] (Combination of immersion and non-immersion)
Germinated brown rice was germinated in the same manner as in Example 1 except that water was absorbed for a total of 23 hours, which was 7 hours in the soaking state and 16 hours in the non-soaking state (water that was continuously applied to the soaking water). It was. Table 1 shows the germination rate of brown rice when 23 hours have passed since the start of washing.
[0038]
[Table 1]

[0039]
[Example 19]
The antioxidant ability of the germinated brown rice obtained in Example 1 was evaluated based on the superoxide (O ₂ ^· ⁻ ) and hydroxyl radical (HO ·) elimination rate and the lipid peroxidation inhibition rate. This is shown in Table 2 together with commercially available germinated brown rice products (Company A).
[0040]
[Table 2]

[0041]
[Example 20]
When brown rice was germinated in the same manner as in Example 1 and approximately 21 hours had passed after the start of soaking, the soaking water was replaced with acidic water having a pH of 2.2 (temperature: 29 ° C.) and circulated for 10 minutes while feeding air, and sterilizing. went.
Next, the germinated brown rice was washed with tap water. Next, air at 20 ° C. was blown to dry the germinated brown rice. The drying time was 160 minutes.
Table 3 shows the hydroxyl radical (HO ·) elimination rate of the germinated brown rice produced as described above.
[0042]
[Examples 21 to 22] (Influence of drying temperature)
Germinated brown rice was produced in the same manner as in Example 19, except that the blowing in the drying step was 50 ° C., 14 minutes (Example 21), 100 ° C., and 4 minutes (Example 22). Table 3 shows the elimination rate of hydroxyl radicals (HO.) Of the produced germinated brown rice.
[0043]
[Table 3]

[0044]
[Example 23] (Food texture test)
How to cook the germinated brown rice obtained in Example 1 above in the same way as white rice (germinated brown rice: 450 g, cooked water: 550 ml of tap water, soaking time before cooking: 60 minutes, electric rice cooker: rice cooker manufactured by Matsushita Electric Industrial Co., Ltd. , IH jar SR-D10A-C, rice cooking time: 52 minutes, steaming time: 10 minutes), and the texture was tested. Moreover, the germinated brown rice of the commercial item (A company, B company, C company) was cooked on the same conditions, respectively. Each cooked rice obtained was compared with the germinated brown rice of the present invention with respect to the texture, with each tester having a score of 1 by 10 testers.
As a result, as shown in Table 4, it was found that the cooked rice of the germinated brown rice of the present invention has a high score, and the texture of the germinated brown rice of the present invention is extremely excellent.
[0045]
[Table 4]

[0046]
【The invention's effect】
According to the present invention, it is possible to germinate brown rice in a short time while suppressing the growth of bacteria, and to obtain germinated brown rice having high antioxidant ability. The germinated brown rice obtained by the present invention has little odor unique to rice bran, has a high nutritional value and antioxidant capacity, and can be used in various fields as a health food that can be eaten deliciously even when cooked alone. .

Claims

A method for producing germinated brown rice having at least a step of allowing brown rice to absorb water and germinating, and a step of drying the germinated brown rice, wherein in the germination step, pH is 2 to 4, temperature is 15 to 35 ° C, and dissolved oxygen concentration A method for producing germinated brown rice, characterized in that brown rice is soaked in 4 ppm or more of water to absorb water, and in the drying step, air is blown at 25 ° C. or less to dry the germinated brown rice.

The method for producing germinated brown rice according to claim 1, wherein the brown rice is washed, and then acid water having a pH of 2 to 3.5 is absorbed into the brown rice and germinated.

The method for producing germinated brown rice according to claim 1 or 2, wherein the germinated brown rice is sterilized with acidic water having a pH of 2 to 3.5 and then dried.

The method for producing germinated brown rice according to any one of claims 1 to 3, wherein the temperature of air blown in the drying step is 20 ° C or lower.

In the germination step, circulate the immersion water while supplying a part of the water in which the brown rice is immersed to the fine water surface and / or circulate while feeding air directly into the immersion water, The method for producing germinated brown rice according to any one of claims 1 to 4, wherein the dissolved oxygen concentration of the immersion water is maintained at 4 ppm or more.

The water content of brown rice before washing is 10%. In the germination step, after the start of immersion, when the water content of brown rice reaches 20-28%, water is replaced only once. producing how the brown rice according to any one.