JP2004041189A - New baker's yeast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a baker's yeast, bread dough containing the yeast and the yeast capable of maintaining a soft eat feeling and improving the commercial value of the bread. <P>SOLUTION: This baker's yeast is characterized by exhibiting ≥320 ml generated amount of carbon dioxide per 50 g dough obtained by mixing after adding 70 g wheat flour and 2.2 g baker's yeast based on 65 % water content to 40 ml water, fermenting the obtained intermediate material dough at 30°C for 4 hr, adding 30 g wheat flour, 6g sugar, 2g table salt and 19 ml water, kneading regularly, incubating the dough at 30°C for 30 min and then measuring the amount of the generated gas at 38°C for 2 hr. <P>COPYRIGHT: (C)2004,JPO

Description

マルトース発酵力測定は表２に示した組成の発酵液を１００ｍｌ三角フラスコに１５ｍｌ分注し、上記培養菌体を５ｍｌの水に懸濁してから該発酵液に加えて、総重量を測定後、３３℃で４時間インキュベートし、再度総重量を測定して、初期重量から炭酸ガス発生により減少した値をマルトース発酵力とした。
【００４４】
【表２】

【００４５】
構成的に発現するマルトース発酵性遺伝子を１遺伝子保有する交雑株の場合、食パン中種法本捏生地での初期炭酸ガス発生量の高い交雑株を取得可能であった。しかし、それら交雑株の炭酸ガス発生量は時間とともに低下し、持続性がみられなかった。一方、構成的に発現するマルトース発酵性遺伝子を少なくとも２遺伝子保有する交雑株は、炭酸ガス発生量が時間とともに低下することもなく、発酵の持続性がみられた。
【００４６】
構成的に発現するマルトース発酵性遺伝子を少なくとも２遺伝子保有する交雑株を得るために、本発明ではまず無糖発酵力の高い自然界からの分離株および保存菌株から胞子株を取得し、それらから構成的に発現するマルトース発酵性遺伝子を有する胞子株を選択し、続いて選択した胞子株を異なる接合型でマルトース発酵力が５０ｍｇ以下の胞子株と交雑し、交雑株のマルトース発酵検定により優性、構成的に発現するマルトース発酵性遺伝子をもった胞子株を複数選択した。
【００４７】
本発明のパン酵母のマルトース発酵性遺伝子はグルコース低抑制性である。マルトース発酵性遺伝子はグルコースの存在により発酵が抑制されるが、本発明におけるパン酵母は低抑制性マルトース発酵性遺伝子を保有し、パン酵母はグルコース存在下でもマルトース発酵が進行する。本発明のパン酵母は低糖生地で砂糖が生地中に存在してもマルトース発酵するため本捏生地における炭酸ガス発生量の増加をもたらし、その結果、持続性を示すことになる。
【００４８】
上記で選択した構成的に発現するマルトース発酵性遺伝子をもつ胞子株を相互に交雑し、作製した交雑株より中種法本捏発酵力の高い菌株を選択した。これらは構成的に発現するマルトース発酵性遺伝子を少なくとも２遺伝子保有しており、選択株からは本捏初期発酵力が高くかつ、本捏発酵力の炭酸ガス発生に持続性を有する菌株が得られた。
【００４９】
本発明のパン酵母を用いて作製したパンは、従来のパン酵母を用いて作製したパンよりも老化が遅いことに特徴を有している。パンの硬さは、一般的にパンに荷重を加えた時のパンからの応力値で表すため、数値が小さいほどパンが柔らかいことを示し、パンが老化するほどこの数値が大きくなっていく。
【００５０】
本発明でいう乳化剤、汎用パン酵母を使用した食パンとは、表３に示した標準的な配合で、表４に示したような条件で作製したパンのことである。一方、乳化剤無添加パンとは、表５に示した乳化剤無添加の配合で、表４に示したような条件で作製したパンのことである。
【００５１】
【表３】

【００５２】
【表４】

【００５３】
【表５】

【００５４】
乳化剤及び汎用パン酵母を使用したパンを室温で３日間保存すると、乳化剤無添加パンと比べて、レオナー測定値が１０％以上低く、食感上も柔らかくなる。本発明のパン酵母では乳化剤無添加でパンを製造しても、乳化剤、汎用パン酵母を使用したパンと較べて−５％〜＋５％の硬さであり、食感上も差が感じられない。また、乳化剤と本発明のパン酵母を併用すると、乳化剤無添加で本発明のパン酵母を用いて製造したパンに較べ、更にレオナー測定値が１０％以上低下し、食感上も柔らかくなる。
【００５５】
ここで、レオナー測定値とは、上記の条件で焼成したパンの端から２ｃｍ厚で２枚を切り捨てた後、更に２ｃｍ厚で６枚をスライスし、クラムの中心部より５ｃｍ四方の大きさの断片を切り取り山電製レオナー（ＲＥ３３０５）にて生地の硬さを測定した値の事である。
【００５６】
本発明のパン酵母を用いて食パン中種法により食パンを製造した場合、従来のパン酵母と比べてホイロ時間の短縮または比容積の増大がみられ、かつ窯伸び良好となり、膜が薄く、ソフトな食パンが得られた。
【００５７】
本発明において、パン酵母はサッカロミセス・セレビシエ（Ｓａｃｃｈａｒｏｍｙｃｅｓ　ｃｅｒｅｖｉｓｉａｅ）に属し、上記方法により選択した交雑株が好ましく、ＫＳＹ２９０が例示できる。このＫＳＹ２９０株はサッカロミセス・セレビシエと同定され、本菌株は２００２年５月１７日にＦＥＲＭ　Ｐ−１８８６３として独立行政法人産業技術総合研究所特許生物寄託センター（日本国茨城県つくば市東１丁目１番地中央第６）に寄託されている。
【００５８】
【実施例】
以下に本発明の実施例を記載するがこれらは本発明を例示的に記載するのみで本発明はこれらの実施例に限定されるものではない。なお、以下の実施例に使用した材料について、小麦粉は日清製粉（株）社製のカメリアを使用し、イーストフードはイーストフードＣ（鐘淵化学工業（株）社製）、ショートニングはスノーライト（鐘淵化学工業（株）社製）を使用した。また乳化剤はモノグリセリド、コハク酸モノグリセリドから成る理研ビタミン（株）社製のパンマック２００Ｂを使用した。その他の製パン材料および製パン副原料は、一般小売店から入手可能なものを使用した。また、対照菌株は鐘淵化学工業（株）から市販されているパン酵母２株及び交雑株ＲＫＢ３４を用いた。
従来パン酵母Ａ（鐘淵化学工業（株）製ＲＥＤイースト）
従来パン酵母Ｂ（鐘淵化学工業（株）製ＭＹイースト）
ＲＫＢ３４（マルトース発酵性遺伝子１個を有する交雑株）
【００５９】
＜レオナー測定値の求め方＞
山電レオナー（ＲＥ３３０５）により、以下の条件に従って、レオナー値を測定した。
プランジャー　　　：６ｃｍ×６ｃｍ
ロードセル　　　　：２ｋｇｆ
アンプの倍率　　　：１倍
測定点数　　　　　：５５０個
測定時間　　　　　：５５ｓｅｃ
測定歪率　　　　　：５０％
測定速度　　　　　：１ｍｍ／ｓｅｃ
戻り距離　　　　　：５ｍｍ
パンの厚さ　　　　：２０ｍｍ
接触面積　　　　　：２５００ｍｍ^２
【００６０】
（実施例１）　　交雑育種
本出願人が保有するサッカロミセス・セレビシエ保存菌株よりマルトース発酵力を有する複数の菌株を元株として使用した。これらの菌株を胞子形成培地により胞子を形成させ、次のステップで交雑育種を実施した。
（１）分離胞子株より高マルトース発酵株を選択した。続いてこれら胞子株に非マルトース発酵株を交雑し、交雑株のマルトース発酵力から胞子株マルトース発酵性の優性、劣性を判定した。
（２）異なる元株に由来する優性、高マルトース発酵株を交雑することにより構成的マルトース発酵性遺伝子を２遺伝子保有する株を作製した。
（３）更に構成的マルトース発酵性遺伝子を３遺伝子保有する菌株を作製するために、（２）の交雑株を胞子化しマルトース発酵性に関する４分子分析よりマルトース発酵性遺伝子が同一染色体上に存在するか否かを判定した。
（４）マルトース発酵性遺伝子が異なる染色体上に存在すると想定される交雑株のマルトース発酵性分離比より、マルトース発酵性遺伝子を２遺伝子保有すると推定される胞子株を選択した。
（５）（４）よりマルトース発酵性遺伝子を２遺伝子保有すると推定される胞子株と他の元株由来の優性、構成的に発現するマルトース発酵性遺伝子を有する胞子株との間で交雑株を作製し、優性、構成的に発現するマルトース発酵性遺伝子を３遺伝子保有する株とした。
【００６１】
上記の（２）および（５）の交雑株より食パン中種法本捏発酵力を指標に選択し、本発明のＫＳＹ２９０株を取得した。
【００６２】
（実施例２）　　パン酵母菌体の作製方法
・バッチ培養
表６組成の培地を５ｍｌ／大型試験管、５０ｍｌ／５００ｍｌ坂口フラスコに分注し、オートクレーブ殺菌した後、培養に使用した。
交雑育種株１白金耳を大型試験管に全量植菌し、３０℃、１日間振とう培養後、５００ｍｌ坂口フラスコに継植、さらに３０℃、１日管振とう培養により作製したバッチ培養菌体を以下の５Ｌジャーの種母培養、ならびに実施例３の２％グルコース低糖生地発酵力測定に供した。
【００６３】
【表６】

【００６４】
・５Ｌジャー種母培養
５Ｌジャーに表７組成の培地２Ｌを入れて、オートクレーブ殺菌後、５００ｍｌ坂口フラスコ５本分の菌体を植菌し表８の条件で種母培養を行った。
【００６５】
【表７】

【００６６】
【表８】

【００６７】
・５Ｌジャー本培養
始発液量を表９の培地組成で、５Ｌジャーで培養した種母菌体を湿菌体として５０ｇ添加し、表１０の条件で本培養を行った。
【００６８】
【表９】

【００６９】
【表１０】

【００７０】
１３時間培養を行い、糖は１２時間培養の間に分割添加した。バッチ培養、ならびに５Ｌジャー培養菌体は培養終了後直ちに遠心分離し、ヌッチェにより吸引脱水し湿菌体を作製、以下の実施例に使用した。実験に使用する際には、湿菌体の水分含量を測定し、使用量は６５％水分に換算した。
【００７１】
（実施例３）　　グルコース２％低糖生地発酵力
表１１に示すパン生地において、実施例２のバッチ培養後、ヌッチェにより吸引脱水、作製したパン酵母ＫＳＹ２９０の湿菌体について炭酸ガス発生量を測定した。その結果を表１２に示す。その際、炭酸ガス発生量測定法は、表１１の生地組成でホバート卓上ミキサーにより３分間ミキシングし、３８℃、４時間の炭酸ガス発生量をファーモグラフ（ＡＴＴＯ社製）にて測定し、５５０ｍｌの炭酸ガス発生に要する時間を比較した。その結果は、表１２に示す。
【００７２】
【表１１】

【００７３】
【表１２】

【００７４】
（比較例１）
パン酵母として、従来パン酵母Ａを用いた以外は、実施例３と同様にして、炭酸ガス発生量を測定し、５５０ｍｌの炭酸ガス発生に要する時間を求めた。その結果は、表１２に示す。
【００７５】
（比較例２）
パン酵母として、従来パン酵母Ｂを用いた以外は、実施例３と同様にして、炭酸ガス発生量を測定し、５５０ｍｌの炭酸ガス発生に要する時間を求めた。その結果は、表１２に示す。
【００７６】
炭酸ガス発生の基質は添加したグルコース２％と小麦粉中に元々存在するマルトースであり、通常、パン酵母はグルコース発酵後にマルトース発酵するため、全基質からの炭酸ガス発生が終了するにはかなりの時間を要する。本発明のパン酵母はグルコース２％と小麦粉中のマルトースから発酵される全炭酸ガス発生量に近い５５０ｍｌの炭酸ガスを１６５分で発生、終了させ、従来パン酵母Ａ、Ｂよりも著しく早い。本発明のパン酵母はグルコースの存在下でもグルコース発酵とマルトース発酵が平行して進行し、グルコース抑制性が低いことを示している。
【００７７】
（実施例４）　　中種法本捏発酵力
表１３に示すパン生地においてパン酵母ＫＳＹ２９０について炭酸ガス発生量を測定した。その結果を表１４に示す。その際炭酸ガス発生量測定法は表１３の生地組成でホバート卓上ミキサーにより３分間ミキシング、３０℃、４時間の中種発酵を行い、発酵した中種生地と本捏生地の材料を混合、更に３分間ミキシングし、分割した生地玉５０ｇについて３０℃、３０分間ベンチタイムを取った後、３８℃でのガス発生量を２時間測定した。また、ベンチタイム後１時間までの炭酸ガス発生量に対する、ベンチタイム後１時間から２時間までの炭酸ガス発生量の比率も算出した。
【００７８】
【表１３】

【００７９】
【表１４】

【００８０】
（比較例３）
パン酵母として、ＲＫＢ３４を用いた以外は、実施例４と同様にして、３８℃での炭酸ガス発生量を２時間測定した。また、ベンチタイム後１時間までの炭酸ガス発生量に対する、ベンチタイム後１時間から２時間までの炭酸ガス発生量の比率も算出した。その結果は、表１４に示す。
【００８１】
（比較例４）
パン酵母として、従来パン酵母Ａを用いた以外は、実施例４と同様にして、３８℃での炭酸ガス発生量を２時間測定した。また、ベンチタイム後１時間までの炭酸ガス発生量に対する、ベンチタイム後１時間から２時間までの炭酸ガス発生量の比率も算出した。その結果は、表１４に示す。
【００８２】
（比較例５）
パン酵母として、従来パン酵母Ｂを用いた以外は、実施例４と同様にして、３８℃での炭酸ガス発生量を２時間測定した。また、ベンチタイム後１時間までの炭酸ガス発生量に対する、ベンチタイム後１時間から２時間までの炭酸ガス発生量の比率も算出した。その結果は、表１４に示す。
【００８３】
本捏で小麦粉に対して糖量を６％添加する食パン中種法での本捏発酵では、本発明のＫＳＹ２９０はＲＫＢ３４、従来パン酵母Ａ、Ｂに比べて高い炭酸ガス発生量を示した。また、１時間までのガス発生量に対する１時間から２時間までのガス発生量の比率は、マルトース発酵性遺伝子を複数個保有するＫＳＹ２９０はマルトース発酵性遺伝子を１個しか保有しないＲＫＢ３４と比べて高い値を示した。さらに、ＫＳＹ２９０の１時間までの発酵力は従来パン酵母Ａ、Ｂに対して向上しているにもかかわらず、１時間までのガス発生量に対する１時間から２時間までのガス発生量の比率は、従来パン酵母Ａ、Ｂ並みの値を示した。これらの結果からＫＳＹ２９０株は持続性のある高い本捏発酵力を有しているといえる。
【００８４】
（実施例５）　　中種法製パン試験（定容積ホイロ法）
表１５に示すパン生地組成、表１６に示す工程においてパン酵母ＫＳＹ２９０について中種製パン試験（定容積ホイロ法）を行った。結果を表１７に示す。
【００８５】
【表１５】

【００８６】
【表１６】

【００８７】
【表１７】

【００８８】
（比較例６）
パン酵母として、従来パン酵母Ａを用いた以外は、実施例５と同様にして、中種製パン試験（定容積ホイロ法）を行った。結果を表１７に示す。
【００８９】
（比較例７）
パン酵母として、従来パン酵母Ｂを用いた以外は、実施例５と同様にして、中種製パン試験（定容積ホイロ法）を行った。結果を表１７に示す。
【００９０】
ＫＳＹ２９０は従来パン酵母Ａ、Ｂと比べてホイロ時間が大幅に短縮されており、かつ窯伸びも良好であるために比容積も大きくなり、中種法での本捏発酵力がすぐれていることが分かる。
【００９１】
（実施例６）　　中種法製パン試験（定時間ホイロ法）
表１８に示すパン生地組成、表１９に示す工程においてパン酵母ＫＳＹ２９０について中種製パン試験（定時間ホイロ法）を行った。結果を表２０に示す。
【００９２】
【表１８】

【００９３】
【表１９】

【００９４】
【表２０】

【００９５】
（比較例８）
パン酵母として、従来パン酵母Ａを用いた以外は、実施例６と同様にして、中種製パン試験（定時間ホイロ法）を行った。結果を表２０に示す。
【００９６】
（比較例９）
パン酵母として、従来パン酵母Ｂを用いた以外は、実施例６と同様にして、中種製パン試験（定時間ホイロ法）を行った。結果を表２０に示す。
【００９７】
従来パン酵母Ａ、Ｂと比べてＫＳＹ２９０株の食パン比容積は向上し、食感は非常にソフトであった。
【００９８】
（実施例７）　　パン老化抑制試験（１）
上述したようにＫＳＹ２９０株を用いて製造したパンは比容積が向上しソフトな食感であったため、さらにパンの硬さを数日の保存期間測定した。表２１に示すパン生地組成（乳化剤添加）、表２２に示す工程においてパン酵母ＫＳＹ２９０について中種法製パン試験を行った。焼成したパンは２時間放置冷却後、ポリエチレン製袋に入れて密封し２５℃で１、３日間保存した。保存後、端から２ｃｍ厚で２枚を切り捨てた後、更に２ｃｍ厚で６枚をスライスした。これらスライスしたパンのクラムの中心部より５ｃｍ四方の大きさの断片を切り取り、そのレオナー値を測定し、その平均値を求めた。レオナー値が低いほどパンが柔らかいことを示している。食感は同一パンを５名のパネラーにより◎、○、○〜△、△、×（順に優、良、並、やや悪い、悪い）の５段階で評価した。その結果を表２３に示す。
【００９９】
【表２１】

【０１００】
【表２２】

【０１０１】
【表２３】

【０１０２】
（実施例８）
表２１に示すパン生地組成において、乳化剤を無添加にした以外は、実施例７と同様にして中種法製パン試験を行い、焼成したパンは２時間放置冷却後、ポリエチレン製袋に入れて密封し２５℃で１、３日間保存した後、そのレオナー値を測定し、また食感を評価した。その結果を表２３に示す。
【０１０３】
（比較例１０）
パン酵母として従来パン酵母Ａを用いた以外は、実施例７と同様にして中種法製パン試験を行い、焼成したパンは２時間放置冷却後、ポリエチレン製袋に入れて密封し２５℃で１、３日間保存した後、レオナー値を測定し、また食感を評価した。その結果を表２３に示す。
【０１０４】
（比較例１１）
パン酵母として従来パン酵母Ａを用いた以外は、実施例８と同様にして中種法製パン試験を行い、焼成したパンは２時間放置冷却後、ポリエチレン製袋に入れて密封し２５℃で１、３日間保存した後、レオナー値を測定し、また食感を評価した。その結果を表２３に示す。
【０１０５】
乳化剤を添加しない製造法の場合、焼成３日後においてＫＳＹ２９０を使用したパンは従来パン酵母Ａを使用したパンよりもレオナー測定値に明らかな差が認められ、従来パン酵母Ａと比べた場合、パンの老化を遅らせる効果があることが認められた。この傾向はパネラーによる食感の評価でも同様であり、本発明のパン酵母を用いて製造したパンの方が柔らかな食感が得られた。
さらにＫＳＹ２９０の特徴として、乳化剤を添加せずに作製したパンでも、従来パン酵母Ａを用いて乳化剤を添加したパンと比較して焼成３日後の硬さは同程度であり、パネラーによる食感評価でも柔らかさに差は感じられなかった。
一般的なパン製造で行なわれているように乳化剤添加をした場合、焼成３日後においてＫＳＹ２９０を使用したパンは従来パン酵母Ａを使用したパンよりもレオナー測定値に明らかな差が認められ、従来パン酵母Ａと比べた場合、パンの老化を遅らせる効果があることが認められた。この傾向はパネラーによる食感の評価でも同様であり、本発明のパン酵母と乳化材を用いて製造したパンは、従来パン酵母Ａと乳化剤を併用した今までのパンにはない柔らかな食感であった。
【０１０６】
（実施例９）　　パン老化抑制試験（２）
室温保存よりも老化が早くパンの品質低下がより顕著となる冷蔵条件下で測定を行なった。表２４に示すパン生地組成（乳化剤添加）、表２５に示す工程においてパン酵母ＫＳＹ２９０について中種法製パン試験を行った。焼成したパンは２時間放置冷却後、ポリエチレン袋に入れて密封し５℃で１、２日間保存した。保存後、端から２ｃｍ厚で２枚を切り捨てた後、更に２ｃｍ厚で６枚をスライスした。これらスライスしたパンのクラムの中心部より５ｃｍ四方の大きさの断片を切り取り山電製レオナー（ＲＥ３３０５）にて生地の硬さを測定し、これらの平均値を求めた。食感は同一パンを５名のパネラーにより◎、○、○〜△、△、×（順に優、良、並、やや悪い、悪い）の５段階で評価した。これらの結果を表２６に示す。
【０１０７】
【表２４】

【０１０８】
【表２５】

【０１０９】
【表２６】

【０１１０】
（実施例１０）
表２４に示すパン生地組成において、乳化剤を無添加にした以外は、実施例９と同様にして中種法製パン試験を行い、焼成したパンは２時間放置冷却後、ポリエチレン製袋に入れて密封し２５℃で１、２日間保存した後、そのレオナー値を測定し、また食感を評価した。その結果を表２６に示す。
【０１１１】
（比較例１２）
パン酵母として従来パン酵母Ａを用いた以外は、実施例９と同様にして中種法製パン試験を行い、焼成したパンは２時間放置冷却後、ポリエチレン製袋に入れて密封し２５℃で１、２日間保存した後、そのレオナー値を測定し、また食感を評価した。その結果を表２６に示す。
【０１１２】
（比較例１３）
パン酵母として従来パン酵母Ａを用いた以外は、実施例１０と同様にして中種法製パン試験を行い、焼成したパンは２時間放置冷却後、ポリエチレン製袋に入れて密封し２５℃で１、２日間保存した後、そのレオナー値を測定し、また食感を評価した。その結果を表２６に示す。
【０１１３】
乳化剤を添加しない場合、あるいは添加した場合ともに、焼成２日後においてＫＳＹ２９０を使用したパンは従来パン酵母Ａを使用したパンよりもレオナー測定値に明らかな差が認められ、従来パン酵母Ａと比べた場合、パンの老化を遅らせる効果があることが認められた。この傾向はパネラーによる食感の評価でも同様であり、本発明のパン酵母を用いて製造したパンの方が柔らかな食感が得られた。さらにＫＳＹ２９０の特徴として、乳化剤を添加せずに作製したパンでも、従来パン酵母Ａを用いて乳化剤を添加したパンと比較して焼成２日後の硬さは同程度であり、パネラーによる食感評価でも柔らかさに差は感じられなかった。
【０１１４】
デンプン質の食品であるパンはマイナス２℃から２℃付近で最も老化速度が速いため、チルド用サンドイッチ食パンではその影響は大きく、室温保存と比べてパンの食感は低下しやすい。本実施例では５℃保存であるため老化進行が比較的速い条件下にあったと考えられるが、このような条件下においても本発明のパン酵母は従来パン酵母と比べて老化が遅く、食感上も柔らかさに差がみられたことは、チルド用サンドイッチ食パン製造に本発明のパン酵母は適していると考えられた。
【０１１５】
【発明の効果】
本発明のパン酵母は優性、構成的に発現し、かつグルコース抑制性の低いマルトース発酵性遺伝子を複数保有し、高いマルトース発酵性を獲得させることを目的として作製された。このために、食パン中種法製パン生地のホイロ発酵での炭酸ガス発生量が多く、この結果、従来のパン酵母と比べてホイロ時間の短縮さらには比容積の増大がみられ、膜が薄くソフトなパンが得られ、同時に乳化剤によって老化がある程度遅延されたパンの老化をさらに遅延させ、結果的に今までのパンよりも柔らかな食感が持続しパンの商品性を高めることが可能となった。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to yeast for bread, bread dough containing bread yeast, and a method for producing bread using bread yeast.
[0002]
[Prior art]
Bread is usually produced by mixing flour, water, baker's yeast, sugar (sugars), salt, fats and oils, dairy products and other auxiliary ingredients, and fermenting with baker's yeast. The amount of sugar used as a fermentation substrate for baker's yeast varies depending on the type of bread, and there are various types of sugar, from French bread to which no sugar is added, bread to be added in small amounts, and confectionery bread to which a large amount of sugar is added.
[0003]
In addition, bread production methods mainly include a straight method and a medium seed method. The straight method is a method in which baker's yeast, sugar, salt, oil, water, etc. are added to flour, mixed and fermented. On the other hand, in the sponge method, bread yeast and water are added to a part of the flour to produce a mixed dough, and the first fermentation, that is, sponge fermentation, is performed and then returned to the mixer. , Fats and oils, etc. and mixing again, followed by secondary fermentation, ie, main kneading fermentation.
[0004]
The suitability of baker's yeast varies depending on the amount of added sugar and the manufacturing method. In the medium seed method with a low sugar concentration such as bread, the baker's yeast is activated during the medium seed fermentation, so that the fermentation proceeds rapidly in the present dough. For this reason, in the present dough with a small amount of added sugar of only a few%, the amount of added sugar in the dough is actively consumed by fermentation, so that the amount of the substrate is limited. There was a problem that the baker's yeast having a higher initial fermentation power of the main kneading reduced the carbon dioxide gas generation amount with time. For this reason, the dough swelling rate is reduced in the latter half of the fermentation, and there is a drawback that the heating time required for obtaining a constant bread volume is prolonged, and the elongation of the kiln during firing becomes insufficient.
[0005]
In a sugar-free dough to which sugar is not usually added, baker's yeast decomposes maltose in flour into two molecules of glucose by maltase, and then ferments.
[0006]
The maltase gene encoding maltase constitutes a maltose fermentable gene by three genes, a gene encoding maltose permease and a gene encoding a regulatory factor required for their expression (Non-Patent Document 1). It is known that the maltose fermentable gene is an overlapping gene present on five different chromosomes, and one of these genes has maltose fermentability when expressed and expressed (Non-Patent Document 2).
[0007]
In general, maltase is an inducible enzyme expressed in the presence of maltose (Non-patent Document 3), and its expression is suppressed in the presence of glucose, so that it is suppressed in a dough to which sugar is added such as ordinary bread. is there. On the other hand, examples of constitutive expression due to mutation of a gene encoding a regulatory factor (Non-patent Documents 4, 5, and 6) have been reported, and examples in which these are recessively expressed (Non-Patent Document 7), and dominant expression (Non-Patent Documents 8 and 9) have been reported.
[0008]
Already, there is an example in which the sugar-free fermentation ability of baker's yeast has been improved by a constitutively expressed maltose-fermentable gene (Non-Patent Document 10). Only one maltose fermentation gene is retained. In normal fermentation, even a single constitutive maltose fermentation gene possessed by baker's yeast exhibits low glucose-suppressing properties, but the main fermentation of the medium-type method does not show low glucose-suppressing properties.
[0009]
In addition to the problem of fermentation power as described above, aging is a problem particularly in bread. Aging is caused by a change in the crystalline state of starch, the main component of flour.
[0010]
Hereinafter, aging will be described. Starch, which accounts for about 70% of flour, has a long structure with glucose as a constituent unit, and is classified into two types, linear amylose and branched amylopectin, depending on the binding method of glucose. They form starch granules.
[0011]
During the baking of the dough, the starch in the flour is heated in the presence of water, so that the amylose flows out of the starch granules, while the branched amylopectin opens its side chains and binds water molecules. The crystallinity is lost, and as a result, the starch immediately after firing is in a soft paste state. Among these, amylose rapidly forms a gel in a relatively short period of time in which the baked bread can remove the rough heat, but is still soft and has high commercial value.
[0012]
However, after a few days, water molecules are released from the branched amylopectin, the side chains of amylopectin close, and when returning to the original crystalline state, the freshness and softness of the bread are lost,ぱ A rough state, a phenomenon generally called aging, progresses, and the commercial value of bread decreases (Non-Patent Document 11).
[0013]
In the manufacture of bread, emulsifiers, α-amylase, and the like are widely used to suppress aging of bread. As the emulsifier, monoglyceride, organic acid monoglyceride and the like are used, and these form a complex with amylose and amylopectin, thereby exhibiting an effect of suppressing recrystallization and delaying aging (Non-Patent Document 12).
[0014]
On the other hand, α-amylase partially degrades amylopectin to dextrin, thereby making it difficult to return to the original molecular state, thereby suppressing recrystallization and delaying aging (Non-Patent Document 13).
[0015]
As described above, aging is suppressed by additives, but aging cannot be completely avoided, and the use of an emulsifier causes the feeling of crunching during bread chewing and the texture is reduced. It is.
[0016]
[Non-patent document 1]
Medical Publishing Center, "New Biotechnology for Yeast", 1990, 235 pages
[0017]
[Non-patent document 2]
Adv. Carbohydr. Chem. Biochem, 1976, 32, 126-234.
[0018]
[Non-Patent Document 3]
Biochim. Biophys. Acta. 1970, 204, 590-609.
[0019]
[Non-patent document 4]
Mol. Cell. Biol. 1986, 6, 2775-2765.
[0020]
[Non-Patent Document 5]
Mol. Gen. Genet. , 1974, 134, 261-272.
[0021]
[Non-Patent Document 6]
Mol. Gen. Genet. 1971, 112, 317-322.
[0022]
[Non-Patent Document 7]
Mol. Cell. Biol. 1986, Vol. 6, pp. 2775-2765.
[0023]
[Non-Patent Document 8]
Mol. Gen. Genet. , 1974, 134, 261-272.
[0024]
[Non-Patent Document 9]
Mol. Gen. Genet. 1971, 112, 317-322.
[0025]
[Non-Patent Document 10]
Chemistry and Biology, 1991, 29, 258-262
[0026]
[Non-Patent Document 11]
Journal of the Bread Science Association, 2001, vol. 47, no. 9, 10, p. 3-15
[0027]
[Non-Patent Document 12]
Journal of the Bread Science Association, 1999, Vol. 45, No. 7, pp. 3-23
[0028]
[Non-patent document 13]
Journal of the Bread Science Society, 2001, vol. 47, no. 5, p. 5-15
[0029]
[Problems to be solved by the invention]
In the present invention, firstly, it is possible to reduce the time required for the stove by increasing the sustainability of the amount of carbon dioxide gas generated in the main kneading process of the medium-class method, to obtain good kiln extensibility and a softer texture than before. Development of baker's yeast that enables aging and, secondly, emulsifiers, additives such as α-amylase, and aging control methods other than the aging delay method by the manufacturing method, providing a softer texture than ever before, The purpose is to develop baker's yeast that can increase the commercial value.
[0030]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have pursued an improvement in the amount of gas generated by supplementing the sugar-limiting rate by utilizing maltose in flour.
[0031]
The present inventors have studied diligently the production of baker's yeast which increases the amount of fermentable sugar by performing maltose fermentation without being suppressed by glucose. As a result, a spore strain having a constitutively expressed glucose-low-suppressing maltose-fermenting gene was obtained, and a strain having at least two such constitutive maltose-fermenting genes was used in a bread loaf fermentation. Maltose fermentation was started even in the presence, and it was found that persistent fermentation was obtained.
[0032]
As a result, a decrease in the amount of gas generated during the main kneading and fermentation was reduced, and a baker's yeast with good elongation was obtained. In addition, by increasing the amount of generated gas and improving the elongation of the kiln, a soft bread was obtained, which had an effect of suppressing aging.
[0033]
That is, the first of the present invention is to ferment the mixed dough obtained by adding 70 g of flour, 2.2 g of baker's yeast converted to 65% moisture and 40 ml of water and mixing at 30 ° C. for 4 hours, and then 30 g of flour, 6 g of sugar and 2 g of salt. And 19 ml of water, and after the main kneading, the dough was incubated at 30 ° C. for 30 minutes, and the amount of carbon dioxide gas measured at 38 ° C. for 2 hours was 320 ml or more per 50 g of the dough.
[0034]
A preferred embodiment is a baker's yeast as described above, characterized by possessing at least two constitutively expressed maltose fermentable genes, more preferably a leoner assay of an emulsifier-free bread after storage at 25 ° C for 3 days. The value described above is + 5% or less as compared with the measured value of bread loon after storage at 25 ° C. for 3 days using an emulsifier and a general-purpose baker's yeast (RED Yeast manufactured by Kaneka Chemical Industry Co., Ltd.). The present invention relates to the above-described baker's yeast, wherein the baker's yeast is particularly preferably the KSY290 strain belonging to Saccharomyces cerevisiae (deposit number: FERM @ P-18863). The second aspect of the present invention is that, after storage at 25 ° C. for 3 days, the measured value of the leonar of the bread without emulsifier is 25 ° C., using a general purpose baker's yeast (RED Yeast manufactured by Kaneka Chemical Industry Co., Ltd.). The present invention relates to a baker's yeast having + 5% or less as compared with the measured value of the leonar of bread after storage for days. A preferred embodiment relates to the above-described baker's yeast, wherein the baker's yeast is KSY290 strain belonging to Saccharomyces cerevisiae (accession number: FERM @ P-18863).
[0035]
A third aspect of the present invention relates to a dough containing the above-described baker's yeast.
[0036]
A fourth aspect of the present invention relates to a method for producing bread using the above-described baker's yeast.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail. The terms used in the present specification are the same as the meanings of the terms usually used in the art, except where specifically described below, and “parts” and “%” are not particularly specified. As far as weight is concerned.
[0038]
The baker's yeast of the present invention has persistence in the main kneading fermentation of the bread medium seed method. That is, the baker's yeast of the present invention was mixed with 70 g of flour, 2.2 g of baker's yeast converted to 65% water content, and 40 ml of water for 3 minutes according to the “Yeast Test Method for Bread” edited by Japan East Industry Association. The fermented dough was fermented at 30 ° C. for 4 hours, and then 30 g of flour, 6 g of sugar, 2 g of salt, and 19 ml of water were added. After mixing for 3 minutes, the dough was incubated at 30 ° C. for 30 minutes, and then incubated at 38 ° C. for 2 minutes. It is characterized in that the carbon dioxide gas generation amount measured over time is not less than 320 ml, preferably not less than 330 ml, more preferably not less than 340 ml per 50 g of the dough. As an example of mixing, the mixing was carried out at a speed of 1 using an N-50 tabletop mixer manufactured by Hobart.
[0039]
In general, baker's yeast, which has a high initial gas generation amount in the main baking fermentation of the bread medium seed method, results in faster consumption of sugar in the main batter and lowering of carbon dioxide gas generation. However, the use of the baker's yeast of the present invention has a sustained carbon dioxide gas generation despite the high initial gas generation amount.
[0040]
The baker's yeast of the present invention is exemplified by baker's yeast produced by crossing a spore strain, but an isolated strain from nature may be used.
[0041]
The baker's yeast having a maltose-fermenting gene constitutively expressed in the present invention refers to a strain showing a high maltose fermenting power and a fermenting power with little glucose suppression in a dough system. In the force measurement, the amount of generated carbon dioxide gas is 100 mg or more per 100 mg of dried bacterial cells.
[0042]
Here, the measurement of the maltose fermentation power was performed as follows. First, a medium having the composition shown in Table 1 was dispensed into a 5 ml / large test tube or a 50 ml / 500 ml Sakaguchi flask, sterilized in an autoclave, and used for culture. One platinum loop of the hybrid breeding strain was inoculated into a large test tube, shake-cultured at 30 ° C. for 20 hours, then subcultured in a 500 ml Sakaguchi flask, and further 10 ml of a culture solution shake-cultured at 30 ° C. for 17 hours was collected. After centrifugation, the maltose fermentation power was measured as follows using the cells washed with water.
[0043]
[Table 1]

The maltose fermentation power was measured by dispensing 15 ml of a fermented solution having the composition shown in Table 2 into a 100 ml Erlenmeyer flask, suspending the cultured cells in 5 ml of water, adding the suspension to the fermented solution, and measuring the total weight. After incubating at 33 ° C. for 4 hours, the total weight was measured again, and the value reduced from the initial weight due to the generation of carbon dioxide was defined as the maltose fermentation power.
[0044]
[Table 2]

[0045]
In the case of the hybrid strain having one constitutively expressed maltose fermentable gene, a hybrid strain having a high initial amount of carbon dioxide gas generated in the present dough using the medium-dough bread method could be obtained. However, the carbon dioxide emission of these hybrids decreased with time, and no sustainability was observed. On the other hand, in the hybrid strain having at least two constitutively expressed maltose fermentable genes, the sustained fermentation was observed without a decrease in the amount of generated carbon dioxide with time.
[0046]
In order to obtain a hybrid strain having at least two constitutively expressed maltose fermentable genes, the present invention first obtains spore strains from isolates and preserved bacterial strains having a high sugar-free fermentation power and constructs them. A spore strain having a maltose fermentation gene that is expressed in a selective manner is selected. Subsequently, the selected spore strain is hybridized with a spore strain having a maltose fermentation power of 50 mg or less in different mating types, and the dominant and constitutive strains are determined by a maltose fermentation assay of the hybrid strain. A plurality of spore strains having a maltose fermentable gene which is expressed in a selective manner were selected.
[0047]
The maltose fermentable gene of the baker's yeast of the present invention is glucose-inhibiting. The maltose fermentable gene is fermented by the presence of glucose, but the baker's yeast in the present invention has a low-suppressive maltose fermentable gene, and the baker's yeast progresses maltose fermentation even in the presence of glucose. The baker's yeast of the present invention is a low-sugar dough and maltose-fermented even if sugar is present in the dough, resulting in an increase in the amount of carbon dioxide gas generated in the present dough, resulting in sustainability.
[0048]
The spore strains having the constitutively expressed maltose fermentation gene selected above were crossed with each other, and a strain having a high fermentation ability in the medium-type method was selected from the prepared cross strains. These have at least two constitutively expressed maltose fermentable genes, and a strain having a high initial kneading fermentation power and a sustained carbon dioxide generation of the main kneading fermentation power is obtained from the selected strain. Was.
[0049]
Bread prepared using the baker's yeast of the present invention is characterized in that aging is slower than bread prepared using conventional baker's yeast. Since the hardness of a bread is generally represented by a stress value from the bread when a load is applied to the bread, a smaller numerical value indicates that the bread is softer, and the larger the bread is, the larger the numerical value is.
[0050]
The bread using the emulsifier and the general-purpose baker's yeast according to the present invention refers to bread prepared with the standard composition shown in Table 3 and under the conditions shown in Table 4. On the other hand, an emulsifier-free bread refers to a bread having no emulsifier added as shown in Table 5 and produced under the conditions shown in Table 4.
[0051]
[Table 3]

[0052]
[Table 4]

[0053]
[Table 5]

[0054]
When bread using an emulsifier and a general-purpose baker's yeast is stored at room temperature for 3 days, the measured Leoner value is 10% or more lower than that of bread without an emulsifier, and the texture becomes soft. Even if bread is manufactured without adding an emulsifier in the baker's yeast of the present invention, the hardness is -5% to + 5% as compared with bread using an emulsifier and a general-purpose baker's yeast, and no difference in texture is felt. . In addition, when the baker's yeast of the present invention is used in combination with the emulsifier, the measured value of leoner is further reduced by 10% or more, and the texture becomes softer than bread produced using the baker's yeast of the present invention without adding the emulsifier.
[0055]
Here, the measured value of the leonar means that after cutting 2 pieces of 2 cm thick from the end of the bread baked under the above conditions, 6 pieces of 2 cm thick were sliced, and 5 cm square from the center of the crumb. A value obtained by cutting a piece and measuring the hardness of the dough using a Leonard (RE3305) manufactured by Sanden.
[0056]
When bread is manufactured by the bread seed method using the baker's yeast of the present invention, compared to conventional baker's yeast, a shortening of the heating time or an increase in specific volume is observed, and the kiln elongation is improved, and the film is thin and soft. Fresh bread was obtained.
[0057]
In the present invention, the baker's yeast belongs to Saccharomyces cerevisiae, and a cross strain selected by the above method is preferable, and KSY290 can be exemplified. This KSY290 strain was identified as Saccharomyces cerevisiae, and this strain was identified as FERM @ P-18863 on May 17, 2002 by the National Institute of Advanced Industrial Science and Technology, Patent Organism Depositary (1-1-1, Higashi, Tsukuba, Ibaraki, Japan) No. 6).
[0058]
【Example】
Hereinafter, examples of the present invention will be described. However, these examples are merely illustrative of the present invention, and the present invention is not limited to these examples. In addition, as for the materials used in the following examples, flour used was Camellia manufactured by Nisshin Flour Milling Co., Ltd .; (Kanebuchi Chemical Industry Co., Ltd.) was used. The emulsifier used was Panmac 200B manufactured by Riken Vitamin Co., Ltd., composed of monoglyceride and succinic acid monoglyceride. Other baking ingredients and baking ingredients used were those available from general retailers. As control strains, two baker's yeast strains and a hybrid strain RKB34 commercially available from Kanegafuchi Chemical Industry Co., Ltd. were used.
Conventional baker's yeast A (RED Yeast manufactured by Kanegafuchi Chemical Industry Co., Ltd.)
Conventional baker's yeast B (MY Yeast manufactured by Kanegafuchi Chemical Industry Co., Ltd.)
RKB34 (Hybrid strain having one maltose fermentable gene)
[0059]
<How to determine the measured value of Leonar>
The Leonard value was measured by Yamaden Leona (RE3305) under the following conditions.
Plunger: 6cm x 6cm
Load cell: 2kgf
Amplifier magnification: 1 time
Number of measurement points: 550
Measurement time: 55 sec
Measurement distortion rate: 50%
Measurement speed: 1 mm / sec
Return distance: 5 mm
Bread thickness: 20mm
Contact area: 2500mm²
[0060]
(Example 1) Crossbreeding
A plurality of strains having maltose fermentation ability from Saccharomyces cerevisiae preserved strains owned by the present applicant were used as original strains. These strains were allowed to form spores in a sporulation medium, and cross breeding was performed in the next step.
(1) A high maltose fermentation strain was selected from the isolated spore strains. Subsequently, a non-maltose fermentation strain was hybridized to these spore strains, and the superiority and the inferiority of the spore strain maltose fermentation were determined from the maltose fermentation ability of the hybrid strain.
(2) A strain having two constitutive maltose fermentable genes was prepared by crossing dominant, high maltose fermentation strains derived from different original strains.
(3) Further, in order to prepare a strain having three constitutive maltose fermentable genes, the hybrid strain of (2) is sporulated and the maltose fermentable gene is present on the same chromosome according to four-molecule analysis on maltose fermentability. It was determined whether or not.
(4) A spore strain presumed to have two maltose fermentable genes was selected based on the maltose fermentative segregation ratio of a hybrid strain in which the maltose fermentable gene is assumed to be present on a different chromosome.
(5) A hybrid strain between a spore strain presumed to have two maltose fermentable genes from (4) and a spore strain having a dominant, constitutively expressed maltose fermentable gene derived from another original strain is produced. This strain was prepared and had three dominant and constitutively expressed maltose fermentable genes.
[0061]
The KSY290 strain of the present invention was obtained from the hybrid strains of the above (2) and (5) by selecting the main method of kneading and fermenting in a bread medium method as an index.
[0062]
(Example 2) Method for preparing baker's yeast cells
・ Batch culture
The medium having the composition shown in Table 6 was dispensed into 5 ml / large test tubes and 50 ml / 500 ml Sakaguchi flasks, sterilized in an autoclave, and used for culture.
Batch-cultured bacterial cells produced by inoculating a platinum loop of the cross breeding strain 1 in a large test tube in total in a large test tube, shaking culture at 30 ° C. for one day, subcultured into a 500 ml Sakaguchi flask, and further shaking culture in a tube at 30 ° C. for one day Was subjected to the following seed culture in a 5 L jar and the measurement of the fermentative power of the 2% glucose-low sugar dough of Example 3.
[0063]
[Table 6]

[0064]
・ 5L jar seed culture
2 L of the medium having the composition shown in Table 7 was placed in a 5 L jar, and after autoclaving, the cells were inoculated into five 500 ml Sakaguchi flasks and seed culture was performed under the conditions shown in Table 8.
[0065]
[Table 7]

[0066]
[Table 8]

[0067]
・ 5L jar main culture
50 g of seed fungal cells cultured in a 5 L jar were added as wet cells with the initial liquid amount in the medium composition of Table 9 and main culture was performed under the conditions of Table 10.
[0068]
[Table 9]

[0069]
[Table 10]

[0070]
Culture was carried out for 13 hours, and sugar was added in portions during the culture for 12 hours. Batch culture and 5 L jar culture cells were centrifuged immediately after completion of the culture, and suction-dehydrated by Nutsche to produce wet cells, which were used in the following Examples. When used in experiments, the moisture content of the wet cells was measured, and the amount used was converted to 65% moisture.
[0071]
(Example 3) Glucose 2% low sugar dough fermentation power
In the bread dough shown in Table 11, after the batch culture in Example 2, the amount of carbon dioxide gas generated was measured for the wet cells of the baker's yeast KSY290 produced by suction dehydration by Nutsche. Table 12 shows the results. At that time, the carbon dioxide generation amount was measured by mixing the dough compositions shown in Table 11 with a Hobart tabletop mixer for 3 minutes, and measuring the carbon dioxide generation amount at 38 ° C. for 4 hours using a pharmograph (manufactured by ATTO). The time required for generating 550 ml of carbon dioxide was compared. The results are shown in Table 12.
[0072]
[Table 11]

[0073]
[Table 12]

[0074]
(Comparative Example 1)
The amount of carbon dioxide generated was measured in the same manner as in Example 3 except that the conventional baker's yeast A was used, and the time required for generating 550 ml of carbon dioxide was determined. The results are shown in Table 12.
[0075]
(Comparative Example 2)
The amount of carbon dioxide generated was measured in the same manner as in Example 3 except that conventional baker's yeast B was used as the baker's yeast, and the time required for generating 550 ml of carbon dioxide was obtained. The results are shown in Table 12.
[0076]
The substrate for carbon dioxide generation is added glucose 2% and maltose originally present in flour. Usually, baker's yeast ferment maltose after glucose fermentation. Cost. The baker's yeast of the present invention generates and terminates 550 ml of carbon dioxide gas in 165 minutes, which is close to the total amount of carbon dioxide produced from glucose 2% and maltose in flour, and is significantly faster than conventional baker's yeasts A and B. In the baker's yeast of the present invention, glucose fermentation and maltose fermentation proceed in parallel even in the presence of glucose, indicating that glucose suppression is low.
[0077]
(Example 4) Medium seed method main kneading fermentation power
In the dough shown in Table 13, the amount of carbon dioxide gas generated from the baker's yeast KSY290 was measured. Table 14 shows the results. At that time, the carbon dioxide generation amount was measured by mixing the dough composition shown in Table 13 with a Hobart table mixer for 3 minutes, performing a medium-type fermentation at 30 ° C. for 4 hours, and mixing the fermented medium-type dough with the material of the main kneaded dough. After mixing for 3 minutes and taking a bench time of 30 minutes at 30 ° C. for 50 g of the divided dough balls, the amount of gas generated at 38 ° C. was measured for 2 hours. Further, the ratio of the amount of carbon dioxide generated from 1 hour to 2 hours after bench time to the amount of carbon dioxide generated until 1 hour after bench time was also calculated.
[0078]
[Table 13]

[0079]
[Table 14]

[0080]
(Comparative Example 3)
The amount of carbon dioxide generated at 38 ° C. was measured for 2 hours in the same manner as in Example 4 except that RKB34 was used as the baker's yeast. Further, the ratio of the amount of carbon dioxide generated from 1 hour to 2 hours after bench time to the amount of carbon dioxide generated until 1 hour after bench time was also calculated. The results are shown in Table 14.
[0081]
(Comparative Example 4)
The amount of carbon dioxide gas generated at 38 ° C. was measured for 2 hours in the same manner as in Example 4 except that the baker's yeast A was used as the baker's yeast. Further, the ratio of the amount of carbon dioxide generated from 1 hour to 2 hours after bench time to the amount of carbon dioxide generated until 1 hour after bench time was also calculated. The results are shown in Table 14.
[0082]
(Comparative Example 5)
The amount of carbon dioxide gas generated at 38 ° C. was measured for 2 hours in the same manner as in Example 4 except that the conventional baker's yeast B was used. Further, the ratio of the amount of carbon dioxide generated from 1 hour to 2 hours after bench time to the amount of carbon dioxide generated until 1 hour after bench time was also calculated. The results are shown in Table 14.
[0083]
In the main kneading fermentation by the bread seed method in which 6% of sugar is added to flour in the main kneading, KSY290 of the present invention showed a higher carbon dioxide gas generation amount than RKB34 and conventional baker's yeasts A and B. In addition, the ratio of the amount of gas generation from 1 hour to 2 hours with respect to the amount of gas generation up to 1 hour is higher in KSY290 having a plurality of maltose fermentable genes than in RKB34 having only one maltose fermentable gene. The values are shown. Furthermore, although the fermentative power of KSY290 up to 1 hour has been improved with respect to conventional baker's yeasts A and B, the ratio of the amount of gas generated from 1 hour to 2 hours with respect to the amount of gas generated up to 1 hour is And values similar to those of conventional baker's yeasts A and B. From these results, it can be said that the KSY290 strain has a sustained and high main kneading / fermenting power.
[0084]
(Example 5) (1) Bread test for medium seed method (constant volume heating method)
In the dough composition shown in Table 15, and in the process shown in Table 16, a baker's yeast test KSY290 was subjected to a medium-type bread making test (constant-volume proofing method). Table 17 shows the results.
[0085]
[Table 15]

[0086]
[Table 16]

[0087]
[Table 17]

[0088]
(Comparative Example 6)
A medium-size bread-making test (constant-volume proofing method) was carried out in the same manner as in Example 5 except that the conventional baker's yeast A was used. Table 17 shows the results.
[0089]
(Comparative Example 7)
A medium-size bread making test (constant volume heating method) was carried out in the same manner as in Example 5 except that the conventional baker's yeast B was used. Table 17 shows the results.
[0090]
KSY290 has a significantly reduced stove time compared to conventional baker's yeasts A and B, and a good kiln elongation, resulting in a large specific volume. I understand.
[0091]
(Example 6) (1) Bread making test by medium seed method (constant-time proofing method)
In the dough composition shown in Table 18, and in the steps shown in Table 19, a baker's yeast test KSY290 was subjected to a medium-type bread making test (constant-time cooking method). The results are shown in Table 20.
[0092]
[Table 18]

[0093]
[Table 19]

[0094]
[Table 20]

[0095]
(Comparative Example 8)
A medium-type bread making test (constant-time proofing method) was performed in the same manner as in Example 6, except that bread yeast A was conventionally used as the bread yeast. The results are shown in Table 20.
[0096]
(Comparative Example 9)
A medium-size bread making test (constant-time proofing method) was performed in the same manner as in Example 6 except that the conventional baker's yeast B was used. The results are shown in Table 20.
[0097]
Compared with the conventional baker's yeasts A and B, the specific bread volume of the KSY290 strain was improved, and the texture was very soft.
[0098]
Example 7 Bread Aging Inhibition Test (1)
As described above, since the bread manufactured using the KSY290 strain had an improved specific volume and a soft texture, the bread hardness was further measured for a storage period of several days. Bread dough compositions (addition of emulsifier) shown in Table 21 and baking yeast KSY290 in the steps shown in Table 22 were subjected to a baking test using the medium seed method. The baked bread was allowed to cool for 2 hours, then placed in a polyethylene bag, sealed, and stored at 25 ° C. for 1 to 3 days. After preservation, 2 pieces were cut off at 2 cm thickness from the end, and then 6 pieces were sliced at 2 cm thickness. A 5 cm square piece was cut out from the center of the crumb of the sliced bread, and its Leoner value was measured, and the average value was obtained. The lower the Leoner value, the softer the bread. The texture of the same bread was evaluated by five panelists in five stages of ◎, 、, △ to △, △, and × (excellent, good, average, slightly bad, bad). The results are shown in Table 23.
[0099]
[Table 21]

[0100]
[Table 22]

[0101]
[Table 23]

[0102]
(Example 8)
In the dough composition shown in Table 21, a breadmaking test was conducted in the same manner as in Example 7 except that no emulsifier was added. The baked bread was allowed to cool for 2 hours, and then sealed in a polyethylene bag. After storage at 25 ° C. for one or three days, the Leonor value was measured and the texture was evaluated. The results are shown in Table 23.
[0103]
(Comparative Example 10)
Except for using the conventional baker's yeast A as the baker's yeast, a bread test was conducted in the same manner as in Example 7. The baked bread was left to cool for 2 hours, then sealed in a polyethylene bag and sealed at 25 ° C for 1 hour. After storage for 3 days, the Leonard value was measured and the texture was evaluated. The results are shown in Table 23.
[0104]
(Comparative Example 11)
Except that the conventional baker's yeast A was used as the baker's yeast, a bread test was performed in the same manner as in Example 8, and the baked bread was allowed to cool for 2 hours, put in a polyethylene bag, sealed, and sealed at 25 ° C for 1 hour. After storage for 3 days, the Leonard value was measured and the texture was evaluated. The results are shown in Table 23.
[0105]
In the case of the production method in which the emulsifier was not added, the bread using KSY290 had a clear difference in the leonar measurement value compared to the bread using the conventional baker's yeast A after 3 days of baking. Was found to be effective in delaying aging. This tendency is the same in the evaluation of the texture by panelists, and the bread produced using the baker's yeast of the present invention had a softer texture.
Further, as a feature of KSY290, bread made without adding an emulsifier has hardness similar to bread conventionally added with an emulsifier using baker's yeast A three days after baking, and texture evaluation by panelists But there was no difference in softness.
When an emulsifier was added as in the case of general bread making, the bread using KSY290 had a clear difference in the measured value of leonar than the bread using the conventional baker's yeast A after 3 days of baking. Compared to the baker's yeast A, it was recognized that there was an effect of delaying the aging of bread. This tendency is the same in the evaluation of texture by panelists, and bread manufactured using the baker's yeast of the present invention and an emulsifier has a softer texture than conventional bread using conventional baker's yeast A and an emulsifier. Met.
[0106]
Example 9 Bread Aging Inhibition Test (2)
The measurement was carried out under refrigerated conditions in which the aging was faster and the deterioration of the bread quality was more remarkable than at room temperature. Bread dough compositions (addition of emulsifier) shown in Table 24 and baking yeast KSY290 in the steps shown in Table 25 were subjected to a baking test using the medium seed method. The baked bread was left standing and cooled for 2 hours, then sealed in a polyethylene bag and stored at 5 ° C. for one or two days. After preservation, two pieces were cut off at 2 cm thickness from the end, and then 6 pieces were sliced at 2 cm thickness. A 5 cm square piece was cut from the center of the sliced bread crumb, and the hardness of the dough was measured with a Sanden Leona (RE3305), and the average value thereof was determined. The texture of the same bread was evaluated by five panelists in five stages of ◎, 、, △ to △, △, and × (excellent, good, average, slightly bad, bad). Table 26 shows the results.
[0107]
[Table 24]

[0108]
[Table 25]

[0109]
[Table 26]

[0110]
(Example 10)
In the dough composition shown in Table 24, except that the emulsifier was not added, a bread test was conducted in the same manner as in Example 9 and the baked bread was left to cool for 2 hours, and then sealed in a polyethylene bag. After storing at 25 ° C. for one or two days, the Leonor value was measured and the texture was evaluated. The results are shown in Table 26.
[0111]
(Comparative Example 12)
Except for using the conventional baker's yeast A as the baker's yeast, a bread test was conducted in the same manner as in Example 9. The baked bread was allowed to cool for 2 hours, then placed in a polyethylene bag, sealed, and sealed at 25 ° C for 1 hour. After storage for 2 days, the Leona value was measured and the texture was evaluated. The results are shown in Table 26.
[0112]
(Comparative Example 13)
Except for using the conventional baker's yeast A as the baker's yeast, a medium-grade bread test was performed in the same manner as in Example 10. The baked bread was allowed to cool for 2 hours, then placed in a polyethylene bag, sealed and sealed at 25 ° C for 1 hour. After storage for 2 days, the Leona value was measured and the texture was evaluated. The results are shown in Table 26.
[0113]
In both cases where the emulsifier was not added or where the emulsifier was added, the bread using KSY290 had a clear difference in the leonar measured value compared to the bread using the conventional baker's yeast A after 2 days of baking, and compared with the conventional baker's yeast A. In this case, the effect of delaying the aging of bread was recognized. This tendency is the same in the evaluation of texture by panelists, and bread produced using the baker's yeast of the present invention had a softer texture. Further, as a characteristic of KSY290, bread made without adding an emulsifier has the same hardness after baking for 2 days as compared with bread conventionally added with an emulsifier using baker's yeast A. But there was no difference in softness.
[0114]
Bread, which is a starchy food, has the fastest aging rate in the vicinity of −2 ° C. to 2 ° C. Therefore, the effect is great in sandwich bread for chilled bread, and the texture of bread tends to deteriorate compared to storage at room temperature. In this example, it is considered that the aging progression was relatively fast due to storage at 5 ° C., but even under such conditions, the baker's yeast of the present invention has a slower aging than conventional baker's yeast, and The difference in softness was also observed above, indicating that the baker's yeast of the present invention was suitable for producing sandwich bread for chilled bread.
[0115]
【The invention's effect】
The baker's yeast of the present invention has multiple maltose-fermenting genes that are dominantly, constitutively expressed, and has low glucose-suppressing properties, and was prepared for the purpose of acquiring high maltose-fermenting properties. For this reason, the amount of carbon dioxide generated in the fermentation of the dough made by the medium-bread bread method is high, and as a result, compared to the conventional baker's yeast, the shortening of the fermentation time and the increase in the specific volume are observed, and the film is thin and soft. Bread was obtained, and at the same time, the aging of bread whose aging was delayed to some extent by the emulsifier was further delayed, and as a result, it became possible to maintain a softer texture than conventional bread and enhance the commerciality of bread. .

Claims (7)

The fermented dough mixed with 70 g of flour, 2.2 g of baker's yeast converted to 65% water and 40 ml of water and mixed at 30 ° C. for 4 hours, and then added with 30 g of flour, 6 g of sugar, 2 g of salt, and 19 ml of water. A baker's yeast having a carbon dioxide gas generation amount of 320 ml or more per 50 g of the dough after the dough is incubated at 30 ° C. for 30 minutes after kneading and then measured at 38 ° C. for 2 hours. The baker's yeast according to claim 1, wherein the yeast has at least two constitutively expressed maltose fermentable genes. The measured value of the Leona of the bread without emulsifier added after storage at 25 ° C. for 3 days is 25 ° C. for the bread after storage at 25 ° C. for 3 days using an emulsifier and a general-purpose baker's yeast (RED Yeast manufactured by Kaneguchi Chemical Industry Co., Ltd.). The baker's yeast according to claim 1, wherein the baker's yeast becomes + 5% or less as compared with the measured value of the leonar. The measured value of the Leoner of the bread without emulsifier added after storage at 25 ° C. for 3 days was 25 ° C. for 3 days after storage at 25 ° C. using an emulsifier and a general-purpose baker's yeast (Kanebuchi Chemical Industry Co., Ltd. RED Yeast). Baker's yeast which is + 5% or less as compared with the measured value of Leonar. The baker's yeast according to any one of claims 1 to 4, wherein the baker's yeast is a KSY290 strain belonging to Saccharomyces cerevisiae (deposit number: FERM @ P-18863). Bread dough containing the baker's yeast according to any one of claims 1 to 5. A method for producing bread using the baker's yeast according to any one of claims 1 to 5.