JP3884975B2 - Tea beverage raw material selection method and tea beverage production method - Google Patents

Description

【００１９】
本発明が提案する茶飲料用原料の選定方法は、茶葉中のストリクチニン含有濃度を指標として原料茶を選択するという方法である。すなわち、茶飲料用原料を選定する段階において、茶葉中のストリクチニン含有濃度を測定し、当該ストリクチニン含有濃度が所定値を超えないことを基準として原料茶を選択する方法である。
【００２０】
上述のように、従来は、官能検査及び近赤外分光光度計による品質評価に基づいて選択した原料茶から実際に茶飲料を試作し、それを長期保存して継続観察しなければ、茶飲料が二次オリを発生するか否かを確かめることができなかった。しかも、同種の茶葉であっても二次オリが発生したり、しなかったりすることがあったため、二次オリを発生しない茶飲料を安定して製造することは困難であった。
これに対し、本発明によれば、原料茶のストリクチニン含有濃度を測定し、当該ストリクチニン含有濃度を指標として原料茶を選定するだけで、二次オリの発生を予想することができ、更には、二次オリを生じない原料茶を選定することができる。
【００２１】
なお、本発明において「茶飲料用原料」又は「原料茶」とは、茶飲料を製造するための原料としての茶（葉や茎を含む）の意であって、生茶葉、荒茶、仕上茶のいずれも包含する意である。
また、本発明で「二次オリ」とは、微粉の沈殿を含まず、フロック状（綿状）の懸濁・沈殿物を意図しており、「一次オリ」とは区別されるべきである。
【００２２】
【発明の実施の形態】
以下、本発明の実施形態について説明する。
【００２３】
（本発明が対象とする原料茶）
本発明が選定の対象とする「茶」は、茶樹（学名：Camellia sinensis ）から摘採した葉や茎であればその品種、産地、摘採時期、摘採方法、栽培方法などを限らず、どのような茶種も包含する。生茶葉等（葉や茎を含む）を原料茶とすることも可能である。また、これらの生茶葉等を蒸すか或いは炒るかなどの手段で酵素活性を停止させる荒茶加工を施した荒茶であれば、煎茶、釜炒り茶、かぶせ茶、玉露、てん茶、抹茶、番茶、焙じ茶、蒸製玉緑茶、釜炒製玉緑茶等のいずれの種類も原料茶として用いることができる。これらの不発酵茶を二種類以上組合わせてもよいし、香料を入れて作製してもよい。加えて、ジャスミン茶などの弱発酵茶も対象とすることができる。なお、ジャスミン茶と言っても、緑茶に人工香料を入れて作製するものは不発酵茶に分類するのが好ましい。
但し、烏龍茶などの半発酵茶、紅茶などの発酵茶並びにプーアル茶などの後発酵茶は含まない。烏龍茶や紅茶で発生するクリームダウンは、緑茶などで発生する不可逆性のフロック状のオリ（すなわち二次オリ）とは異なる原因によるものである。
また、仕上茶としては、上記の荒茶に現在公知の仕上加工を施したものであればいずれも原料茶とすることができる。
【００２４】
なお、茶葉の品種、産地、摘採時期、摘採方法、栽培方法などが異なれば茶葉中のストリクチニン含有濃度が異なること、同品種の茶（Camellia sinensis）であっても茶期、熟度が増すにつれ、言い換えれば茶葉繊維量が増すにつれてストリクチニン含有濃度は減少する傾向があることを本発明者は確かめている。
【００２５】
（茶葉のストリクチニン含有濃度の測定法）
ストリクチニンはタンニンの一種であるから、茶葉のストリクチニン含有濃度を測定するには、茶のタンニン定量法或いはカテキン定量法における公定分析法（農林水産省野菜・茶業試験場「茶の分析法」茶業研究報告 第７１号（１９９０））に従って測定するのが好ましい。
ところが、本発明者が種々の試験をした結果、上記の公定分析法において定められた測定用試料溶液調製法に従って茶を熱水抽出するよりも、酸性熱水を用いて茶を抽出した方が茶葉からストリクチニンを多量かつ容易に抽出することができ、しかも、酸性熱水抽出によって得られた抽出液のストリクチニン含有濃度の方が二次オリ発生との相関性がより一層高いことが判明した。
そこで、本発明では、茶葉のストリクチニン含有濃度の測定方法として、公定分析法で定められた測定用試料溶液調製法に基づく方法、すなわち茶葉を熱水で抽出し、得られた抽出液中のストリクチニン含有濃度を測定する「熱水抽出法」と、前記熱水抽出法における熱水抽出を酸性熱水抽出に置き換えた方法、すなわち茶葉を酸性熱水で抽出し、得られた抽出液中のストリクチニン含有濃度を測定する「酸性熱水抽出法」とを提案する。
【００２６】
熱水抽出法では、茶葉を熱水、例えば約６０〜１００℃、好ましく７０〜１００℃の熱水で約５〜６０分間、好ましくは１０〜３０分間抽出し、冷却後濾過し、この抽出液から茶のタンニン定量法（比色定量法）或いはカテキン定量法における公定分析法（ＨＰＬＣ法）（農林水産省野菜・茶業試験場「茶の分析法」茶業研究報告 第７１号p52-55（１９９０））の測定用試料溶液を調製し、ストリクチニンを測定するのが好ましい。なお熱水に代えて、親水性有機溶媒、含水親水性有機溶媒で抽出することも可能である。
他方、酸性熱水抽出法では、茶葉を酸性熱水、例えばｐＨ約４．５以下、約６０〜１００℃、好ましく７０〜１００℃の酸性熱水で、約５〜６０分間好ましくは１０〜３０分間抽出し、冷却後濾過し、この抽出液から茶のタンニン定量法（比色定量法）或いはカテキン定量法における公定分析法（ＨＰＬＣ法）（農林水産省野菜・茶業試験場「茶の分析法」茶業研究報告 第７１号p52-55（１９９０））の測定用試料溶液を調製し、ストリクチニンを測定するのが好ましい。なお、酸性熱水に代えて、親水性有機溶媒、含水親水性有機溶媒を酸性にして抽出することも可能である。
【００２７】
具体的には、例えば、茶（生茶葉、荒茶、仕上茶）をミルなどで粉砕し、得られた茶葉（１．０ｍｍ目を通過させたもの）を１００ｍｌメスフラスコに秤量する。これにリン酸などの酸を添加してｐＨ７以下、好ましくはｐＨ４．５以下に調製した約６０〜１００℃、好ましくは７０〜１００℃の酸性熱水で約５〜６０分間、必要に応じて攪拌しながら抽出する。そして、得られた抽出液を室温まで冷却後、イオン交換水或いは前記リン酸添加イオン交換水を加えて全量を１００ｍｌに定量し、これをフィルターで濾過し、得られた濾液を測定用試料溶液とするのが好ましい。
【００２８】
（原料茶選定の指標）
二次オリが発生しない可能性の高い原料茶を選定するためには、測定した茶葉中ストリクチニン含有濃度が所定の範囲に入るか否かを基準に選定すればよいが、この際、熱水抽出法によって測定したストリクチニン含有濃度か、酸性熱水抽出法によって測定したストリクチニン含有濃度か、有機溶媒並びに含水有機溶媒抽出法によって測定したストリクチニン含有濃度か、或いは有機溶媒並びに含水有機溶媒酸性抽出法によって測定したストリクチニン含有濃度かによってその基準を変更するのが好ましい。
【００２９】
すなわち、熱水抽出法によって得られた抽出液のストリクチニン含有濃度から求めた茶葉中のストリクチニン含有濃度を指標とする場合、緑茶などの不発酵茶においては、ストリクチニン含有濃度が０．１４％以下の範囲の茶を原料茶として選択すれば二次オリが発生する可能性を低くすることができ、中でも特に０．１０％以下の範囲の茶を選択すれば二次オリ発生の可能性を極めて低くすることができる。ジャスミン茶などの弱発酵茶においては、ストリクチニン含有濃度が０．４９％以下の範囲の茶を選択すれば二次オリ発生の可能性を低くすることができ、中でも特に０．３３％以下の範囲の茶を選択すれば二次オリ発生の可能性を極めて低くすることができる。
【００３０】
他方、酸性熱水抽出法によって得られた抽出液のストリクチニン含有濃度から求めた茶葉中のストリクチニン含有濃度を指標とする場合は、緑茶などの不発酵茶においては、ストリクチニン含有濃度が０．４３％以下の範囲の茶を原料茶として選択すれば二次オリが発生する可能性は低くすることができ、中でも特に０．３７％以下の範囲の茶を選択すれば二次オリ発生の可能性を極めて低くすることができる。ジャスミン茶などの弱発酵茶においては、ストリクチニン含有濃度が０．９０％以下の範囲の茶を選択すれば二次オリ発生の可能性を低くすることができ、中でも特に０．６１％以下の範囲の茶を選択すれば二次オリ発生の可能性を極めて低くすることができる。
【００３１】
（茶飲料の製造方法）
以下、上記の如く選定した茶を用いて、二次オリを発生しない茶飲料を製造するための方法の一例について説明する。
なお、ここでは緑茶飲料の製造方法について説明するが、その他の不発酵茶、或いはジャスミン茶などの弱発酵茶の場合も、通常行われている製造方法に供することによって二次オリを発生しない茶飲料を製造することができる。
【００３２】
上記の如く選定した茶は、現在行われている茶飲料の製造方法、一例を挙げれば、原料茶葉を抽出する抽出工程、抽出液を濾過する濾過工程、抽出液の濃度及びｐＨを調製する調合工程、調合液を加熱殺菌する殺菌工程を備えた茶飲料の製造方法に供することにより二次オリを生じない茶飲料を製造することができる。この際、加熱殺菌前の茶抽出液又は茶調合液のストリクチニン含有量を、約６ｐｐｍ以下、特に５ｐｐｍ以下とするように製造管理するのが好ましい。加熱殺菌前の茶抽出液又は茶調合液のストリクチニン含有量が約５〜６ｐｐｍ以下であれば二次オリを発生しないことが確かめられているからである。また、加熱殺菌前の茶抽出液又は茶調合液中の茶固形分に対するストリクチニン含有量を約０．２〜０．５％以下、特に０．２〜０．４％以下とするように管理してもよい。但し、本発明の茶飲料の製造方法をこの例に限定するものではない。
以下、各工程について詳しく説明する。
【００３３】
「茶の抽出」は、例えば、常法に従ってニーダーと呼ばれる抽出装置を用いて、原料茶葉に対して２０〜５０倍量、０〜１００℃の抽出水で約１〜２０分間、必要に応じて１回〜数回攪拌して、常圧で抽出を行えばよい。但し、抽出方法及び抽出条件等を特に限定するものではなく、例えば加圧抽出を行ってもよい。
抽出の際に用いる抽出水としては、硬水、軟水、イオン交換水、天然水、アスコルビン酸含有水溶液及びｐＨ調製水等を例示することができる。この際、抽出によって得られる抽出液中のストリクチニン含有量は抽出水のｐＨによって左右されるため、抽出水のｐＨを酸性領域、中でもｐＨ４．５以下にすると、抽出液中のストリクチニン含有量が多くなる。よって、逆に抽出液のｐＨを高めることによって、抽出液中のストリクチニン含有量を低減させることができる。例えば、加熱殺菌工程前の茶調合液のストリクチニン含有量を測定した結果、ストリクチニン含有量が所定値（約５〜６ｐｐｍ）を超える場合には、抽出水のｐＨを５以上、特に６以上に設定することによりストリクチニン抽出量を有効に抑えることができる。但し、弱酸性領域或いは中性領域での抽出は単に抽出液中のストリクチニン含有濃度を低下させる制御手段の一つとして開示するものであり、本発明における茶飲料の製造方法において弱酸性領域或いは中性領域で抽出することを好ましいとするものではない。また、抽出水のｐＨを高めるとカテキンの変質が問題となってくるため、ｐＨ６．５〜７程度を上限値とするのが好ましい。
抽出温度すなわち抽出する温水の温度も抽出液中のストリクチニン含有量を左右し得るが、抽出温度は一般的に約４５〜１００℃、特に６０〜９０℃の温水で抽出するのが好ましい。
【００３４】
抽出によって得られた抽出液は、必要に応じて５〜４０℃程度に冷却する。同時に又はその前後に、必要に応じて、抽出液にアスコルビン酸やアスコルビン酸ナトリウムなどを加えて酸性（ｐＨ４〜５）に調製してもよい。抽出液を冷却或いは酸性調製することによって抽出成分の酸化を防ぐことができると共に、一次オリ原因成分を沈殿させて後工程の遠心分離の効率を高めることができる。
【００３５】
「濾過工程」は、例えば、茶葉や大きな微粉などの抽出残渣を除去する粗濾過、並びに、一次オリの原因物質を除去する濾過を行うのが好ましい。但し、これらの粗濾過及び一次オリ原因物質除去濾過を製造工程中のどこに挿入するかは任意である。
粗濾過は、ネル、ステンレスフィルター、ストレーナーその他抽出残渣を除去するために現在採用されている濾過方法を任意に採用することができる。
一次オリの原因物質を除去する濾過方法としては、遠心分離に続いて珪藻土濾過或いは適当な膜濾過を行うなどの方法がある。
ちなみに、遠心分離は、例えば５０００〜１００００ｒｐｍの回転数で行えばよく、遠心分離するに当たっては上記の如く予め抽出液又は調合液を５〜４０℃程度に冷却するのが好ましい。
なお、珪藻土濾過を行う場合には必ずしも遠心分離を挿入する必要はないが、前工程に遠心分離を挿入することにより珪藻土濾過の負担軽減、例えば透過流量の増加により濾過時間を短縮することができる。
膜濾過としては、微細濾過、精密濾過、限外濾過、逆浸透膜濾過、電気透析、生物機能性膜などの膜分離を挙げることができ、上記珪藻土濾過などの濾過助剤を用いた濾過と組合わせて行うようにしてもよい。
上記遠心分離、珪藻土濾過及び膜濾過の方法及び条件設定などは任意に調整可能である。なお、遠心分離、珪藻土濾過及び膜濾過の方法及び条件設定を如何に変更させると、ストリクチニン含有量がどのように変化するかまでは明らかになっていないが、遠心分離、珪藻土濾過及び膜濾過の方法及び条件設定を様々に変化させてストリクチニン含有量を測定し、この測定値を指標として遠心分離、珪藻土濾過及び膜濾過の濾過方法の決定及び条件設定などの製造管理を行うのが好ましい。
【００３６】
「調合工程」は、通常の茶飲料の製造方法と同様、水（硬水、軟水、イオン交換水、天然水その他）、アスコルビン酸、アスコルビン酸ナトリウム、重曹、糖類、デキストリン、香料、乳化剤、安定剤、或いはその他の呈味原料などのいずれか或いはこれらのうち二種以上の組合わせを添加し、主にｐＨ調製、濃度調製、味の調整を行うようにすればよい。
二次オリとの関係で言えば、濃度（Ｂｒｉｘ値）を低下させると、加熱殺菌によってストリクチニンが分解して生じる「エラグ酸」と結合する相手成分（タンパク質など）の濃度を低下させることができるから、二次オリの発生を防ぐことができる。よって、例えば加熱殺菌工程前の茶調合液のストリクチニン含有量を測定した結果、茶調合液のストリクチニン含有量が所定値（約５〜６ｐｐｍ）を超えている場合は、茶調合液の濃度（Ｂｒｉｘ値）を低くすることも製造管理における対処法の選択肢の一つである。但し、茶飲料の香味を考慮すると、茶調合液の濃度（Ｂｒｉｘ値）は約０．１〜０．４、特に０．２〜０．３に設定するのが好ましい。
【００３７】
「加熱殺菌工程」は、缶飲料であれば、上記調合工程で得られた調合液を必要に応じて再加熱した後、調合液を充填し、加熱殺菌（例えば、適宜加圧下（１．２mmHgなど）の下、１２１℃で７分間レトルト殺菌する。）を行い、プラスチックボトル飲料の場合にはＵＨＴ殺菌（調合液を約１２０〜１５０℃で１〜数十秒保持する。）を行うようにすればよい。
加熱殺菌の方法及び条件設定を如何に変更させるとストリクチニン含有量がどのように変化するかまでは明らかになっていないが、少なくとも、現在行われているレトルト殺菌やＵＨＴ殺菌などの加熱殺菌によって調合液中のストリクチニンはエラグ酸に分解され、そのエラグ酸が二次オリの核となることが以下の試験結果から明らかである。
【００３８】
試験１（沈殿形成試験）
市販の緑茶（仕上茶：伊藤園社製「おーいお茶」高地初摘み１５００）２０ｇを７０℃の蒸留水（ｐＨ５．９）８００ｍｌで３．５分間抽出し、遠心分離（７０００rpm、１０分）により不溶性画分を除去し、その上清をポリスチレン樹脂（商品名：DIAION HP-20(三菱化学社製)）を充填したカラムに通して「HP-20非吸着画分」を得た。次いで、蒸留水で当該カラムを洗浄後、８０％メタノール水溶液で溶出し、濃縮乾固して「HP-20吸着８０％メタノール画分」を得た。
【００３９】
上記で得られた各画分について次のように沈殿形成試験を行った。
「HP-20非吸着画分」は、得られた「HP-20非吸着画分」Ｂｘ０．４、２００ｍｌ、「HP-20吸着８０％メタノール画分」は、得られた「HP-20吸着８０％メタノール画分」０．５ｇ、また、「HP-20非吸着画分＋HP-20吸着８０％メタノール画分」は、「HP-20非吸着画分」Ｂｘ０．４、２００ｍｌに「HP-20吸着８０％メタノール画分」０．５ｇを加えて、それぞれアスコルビン酸、重曹及びイオン交換水を用いてアスコルビン酸５００ｐｐｍ、５００ｍｌ、ｐＨ６．０に調製し、１２１℃、７分間の加熱殺菌後、３７℃で保管して観察した。
上記観察の結果を下記表１に示す。
【００４０】
【表１】

【００４１】
「HP-20非吸着画分＋HP-20吸着８０％メタノール画分」のみに二次オリ（フロック状の沈殿）の発生が認められた。このことから、「HP-20非吸着画分」「HP-20吸着８０％メタノール画分」のそれぞれに二次オリの原因となる物質が少なくとも一成分ずつ含まれているものと考えることができた。
【００４２】
試験２（オリの成分分析試験）
本試験の作業手順の概略を図１に示す。
市販の緑茶（仕上茶：伊藤園社製「おーいお茶」高地初摘み１５００）２０ｇを７０℃の蒸留水（ｐＨ５．９）８００ｍｌで３．５分間抽出し、遠心分離（７０００rpm、１０分）により不溶性画分を除去し、その上清をポリスチレン樹脂（商品名：DIAION HP-20(三菱化学社製)）を充填したカラムに通し、次いで、蒸留水で当該カラムを洗浄後、２０％、４０％、６０％、８０％、１００％メタノール水溶液で段階的に溶出させた。
【００４３】
得られた各画分を、試験１と同様、「HP-20非吸着画分」（Ｂｒｉｘ０．４）に添加して沈殿形成試験を行ったところ、「HP-20吸着２０％メタノール画分」及び「HP-20吸着４０％メタノール画分」に二次オリ（フロック状の沈殿）の生成が確認された。特に「HP-20吸着２０％メタノール画分」での生成量は多かった。
【００４４】
そこで、「HP-20吸着２０％メタノール画分」を濃縮乾固後、ＯＤＳ（：逆相系樹脂（商品名：コスモシール７５Ｃ１８ＯＰＮ（ナカライテスク社製））を充填したカラムに通し、次いで、蒸留水で当該カラムを洗浄後、１０％、２０％、３０％メタノール水溶液で段階的に溶出させた。
【００４５】
得られた各画分について、HP-20の分画物と同様の沈殿形成試験を行ったところ、「ODS吸着１０％メタノール画分」の沈殿生成量が多かったため、この「ODS吸着１０％メタノール画分」を更に逆相系カラム（Wakosil-II５Ｃ18HG Prep）を用いた高速液体クロマトグラフィー（ＨＰＬＣ：LC-908 Recycling Preparative HPLC(JAPAN ANALYTICAL INDUSTRY CO.LTD社製)で分取し、メタノール：水：酢酸＝２２：７８：０．１からなる溶媒で得られた６つのピークのそれぞれについて更に同様の沈殿形成試験を行った。
【００４６】
その結果、そのうちの「ピーク３」に沈殿形成が認められたため、「ピーク３」をＬＣ−ＭＳ及びＮＭＲで同定したところ、ストリクチニンであることが分かった。
なお、「HP-20吸着４０％メタノール画分」についても上記同様試験したところ、やはりストリクチニンが含まれていた。また、この画分中のストリクチニン以外の成分は沈殿形成に関与していないことも分かった。
【００４７】
試験３（ストリクチニンの飲料加工特性）
７０℃、８００ｍｌのイオン交換水（ｐＨ５．９）に市販の緑茶（仕上茶：伊藤園社製「おーいお茶」高地初摘み１５００）２０ｇを添加し、攪拌した後１分毎に攪拌しながら３．５分間抽出した。その後、メッシュ（１５０メッシュ）で粗濾過し、室温まで冷却し、ネル（５０μｍ）により濾過した。得られた抽出液にアスコルビン酸０．４ｇを添加し、７０００ｒｐｍ、１０分遠心分離後、その上清を微細濾過（アドバンテック社製１μｍMF膜）し、濾液にアスコルビン酸０．６ｇを更に加え、イオン交換水と重曹とを用いてＢｒｉｘ０．３、ｐＨ６．０に調製して「加熱殺菌前調合液」を得た。
この「加熱殺菌前調合液」を９７℃まで加熱した後、缶に充填し、急冷後１２１℃、７分間のレトルト殺菌を行い、その後冷却して「加熱殺菌後調合液」を得た。
得られた「加熱殺菌前調合液」及び「加熱殺菌後調合液」を攪拌して０．４５μｍフィルターで処理した後、下記条件（ＨＰＬＣ条件・表２）の下で高速液体クロマトグラフィー（ＨＰＬＣ）にてストリクチニン濃度を測定した。
【００４８】
（ＨＰＬＣ条件）
装置：日立D−7000アドバンストHPLC、D−7000型アドバンストHPLCシステムマネージャー
カラム：Wakosil−II５Ｃ18HG φ４．６×（３０＋２５０）ｍｍ
カラム温度：４０℃
流速：０．６ｍｌ／ｍｉｎ
検出：UV２８０
移動相Ａ：１５％ＭｅｔＯＨ（０．１％リン酸）
移動相Ｂ：４５％ＭｅｔＯＨ（０．１％リン酸）
【００４９】
【表２】

【００５０】
サンプルは５μＬインジェクションし、１９min付近に現れるピークを、試験２で抽出・精製したストリクチニンを標品として絶対検量線法により定量した。結果を下記表３に示す。
【００５１】
【表３】

【００５２】
この結果から、ストリクチニンは加熱殺菌によって分解又は沈殿したものと考えることができた。また、茶飲料の製造工程で一般的に行われている加熱殺菌によって飲料中のストリクチニンはほぼ完全に分解するため（ＵＨＴ殺菌の場合には若干分解されないものがあった。）、通常市販されている茶飲料にはストリクチニンはほとんど含まれないことが分かった。
【００５３】
試験４（ストリクチニンの加熱分解試験）
精製ストリクチニン５ｍｇとアスコルビン酸２５０ｍｇとをイオン交換水に溶かし、イオン交換水と重曹とを用いてｐＨ６．０、５００ｍｌに調製し、この調製液を１２１℃、７分間のレトルト殺菌に供した。
そして、「加熱殺菌前調製液」及び「加熱殺菌後調製液」のそれぞれについて、試験３と同様に高速液体クロマトグラフィー（ＨＰＬＣ）にかけたところ４０分付近にピークが現れた。このピークをＬＣ−ＭＳ及びＮＭＲで同定したところ、エラグ酸であることが分かった。結果を図２に示す。
この結果、ストリクチニンをレトルト殺菌すると、エラグ酸を生成するという結果を得ることができた。
【００５４】
また、精製ストリクチニン５ｍｇを試験１で得た「HP-20非吸着画分」（Ｂｒｉｘ０．4）２００ｍｌに添加し、イオン交換水と重曹とを用いてｐＨ６．０、５００ｍｌに調製した後、この調製液を１２１℃、７分間のレトルト殺菌に供し、上記同様、「加熱殺菌前調製液」及び「加熱殺菌後調製液」のそれぞれについてＨＰＬＣでストリクチニン及びエラグ酸を測定した。この結果を図３に示す。ところが、この場合には「加熱殺菌後調製液」中にエラグ酸はほとんど検出されなかった。これより、茶飲料を加熱殺菌すると、飲料中のストリクチニンが分解してエラグ酸を生成し、このエラグ酸が「HP-20非吸着画分」に含まれる成分と結合して沈殿すなわち二次オリを形成するものと考えることができた。
【００５５】
試験５（抽出時ｐＨの比較試験）
酸性水溶液又は塩基性水溶液で茶を抽出した場合のストリクチニン抽出量を比較した。
【００５６】
７０℃、８００ｍｌのイオン交換水（ｐＨ５．９）、酸性水溶液又は塩基性水溶液を用意し、これに市販の緑茶（仕上茶：伊藤園社製「おーいお茶」高地初摘み１５００）２０ｇを添加し、攪拌した後１分毎に攪拌しながら３．５分間抽出した。その後、メッシュ（１５０メッシュ）で粗濾過し、室温まで冷却し、ネル（５０μｍ）により濾過した。得られた塩基性抽出液及びイオン交換水抽出液にアスコルビン酸０．５ｇを加え、酸性抽出液は無添加のまま７０００rpm、１０分の遠心分離にかけ、その上清を微細濾過（アドバンテック社製１μｍMF膜）し、濾液にアスコルビン酸０．５ｇを加え、更にイオン交換水を用いて最終液量２０００ｍｌに調製して調合液を得、当該調合液のストリクチニン濃度を試験３と同様にＨＰＬＣで定量した（表４）。
【００５７】
なお、上記酸性水溶液は、イオン交換水（ｐＨ５．９）８００ｍｌにアスコルビン酸０．５ｇを加えてｐＨ３．４に調製し、塩基性水溶液は、イオン交換水（ｐＨ５．９）８００ｍｌに重曹０．５ｇを加えてｐＨ８．５に調製した。
【００５８】
【表４】

【００５９】
この結果、酸性抽出するとストリクチニン抽出量が多くなることが分かった。
【００６０】
試験６（酸性抽出でのストリクチニン抽出量の比較）
イオン交換水（pH５．９）８００ｍｌにアスコルビン酸０．５ｇを添加してｐＨ３．４とし、９０℃、７０℃、５０℃、３０℃の各温度で１０分間抽出し、試験５の酸性水溶液と同様に調製した調合液を得、当該調合液のストリクチニン濃度を試験３と同様にＨＰＬＣで定量した（表５）。
【００６１】
【表５】

【００６２】
この結果、７０℃以上でストリクチニンの抽出量が多いことが分かった。
【００６３】
試験７（抽出時間の比較）
イオン交換水（pH５．９）８００ｍｌにアスコルビン酸０．５ｇを添加してｐＨ３．４、抽出時間を３分、５分又は２０分間とし、試験５の酸性水溶液と同様に調製した調合液を得、当該調合液のストリクチニン濃度を試験３と同様にＨＰＬＣで定量した（表６）。
【００６４】
【表６】

【００６５】
試験６に示した７０℃、１０分の抽出と、試験７に示した７０℃、２０分での抽出は、ストリクチニン濃度の比較で差は見られなかった。従って、試験５から試験７よりストリクチニン抽出量を多くするには７０℃以上、ｐH４．５以下の酸性水溶液で５分以上抽出するのが好ましいと考えられる。
【００６６】
試験８（エラグ酸添加試験）
試験１で得た「HP-20非吸着画分」にエラグ酸を添加して沈殿形成を確認した。
【００６７】
試験１で得た「HP-20非吸着画分」（Ｂｒｉｘ０．4）２００ｍｌに市販エラグ酸（シグマ社製）２．１ｍｇ及びアスコルビン酸２５０ｍｇを添加し、イオン交換水と重曹とを用いてｐＨ６．０、５００ｍｌに調製し、この調製液を１２１℃、７分間のレトルト殺菌に供し、得られた「エラグ酸＋HP-20非吸着画分」溶液を３７℃で保管し経時変化を観察した。
また、市販エラグ酸（シグマ社製）２．１ｍｇ及びアスコルビン酸２５０ｍｇをイオン交換水に添加し、イオン交換水と重曹とを用いてｐＨ６．０、５００ｍｌに調製し、この調製液を１２１℃、７分間のレトルト殺菌に供し、得られた「エラグ酸のみ」溶液を上記同様に観察した。
この結果を下記表７に示す。
【００６８】
【表７】

【００６９】
上記の試験結果を総合して考察すると、茶抽出液中のストリクチニンは加熱殺菌によって分解されてエラグ酸を生成し、このエラグ酸が「HP-20非吸着画分」に含まれる成分と結合することにより茶飲料でフロック状の沈殿物すなわち二次オリを生成することが解明された。
【００７０】
試験９（「HP-20非吸着画分」中の沈殿生成に関与する成分の分析）
茶飲料で生成したフロック状の沈殿物（オリ）を塩酸−メタノール処理し、当該沈殿物に含まれるエラグ酸を溶解させて当該沈殿物の成分分析を行った。
【００７１】
試験１の方法で製造した茶飲料（「HP-20非吸着画分＋HP-20吸着８０％メタノール画分」）を５日間、３７℃にて保管して沈殿物を生成させ、ＭＳｆｉｌｔｅｒ（０．４５μｍ）を用いて当該沈殿物を回収した。次いで当該ｆｉｌｔｅｒをメタノールで洗浄後、遠心分離にかけて沈殿物を回収し、更に１％塩酸−メタノールで洗浄後、再び遠心分離にかけ風乾した後、ＳＤＳ−ＰＡＧＥ用サンプルとした。
【００７２】
ＳＤＳ−ＰＡＧＥで沈殿物に含まれる成分を分析した結果、当該沈殿物中にはタンパク質が多く含まれることが判明した。また、当該沈殿物中の糖質分析を行ったところ、糖質はほとんど検出されなかった。
【００７３】
試験１０（アミノ酸、タンパク質を用いたモデル試験）
試験管にエラグ酸１ｍｇ、下記表８に示す各アミノ酸標品（協和発酵社製）及び牛血清アルビミン（シグマ社製）をそれぞれ表８に示す添加量にて投入し、イオン交換水を加えて１０ｍｌにした。その後、１２１℃、１５分の加熱殺菌を行い、室温にて保管して観察した。
また、コントロール（エラグ酸１ｍｇにイオン交換水を加えて１０ｍｌ溶解したもの）も同様に加熱殺菌及び保管して観察した。
【００７４】
【表８】

【００７５】
各アミノ酸標品は、室温にて１８日間保管するとフロック状の沈殿が観察された。
加熱殺菌前の牛血清アルビミン添加溶液はフロック状の沈殿を生成することはなかったが、加熱殺菌した当該溶液にはフロック状の沈殿の生成が見られた。
以上の結果から、エラグ酸と結合してフロック状の沈殿（二次オリ）を形成する物質は、アミノ酸、ペプチド及びタンパク質であり、これらの成分が加熱処理或いは長期保存によって変性するためフロック状の沈殿を形成するものと考えることができた。
【００７６】
試験１１（茶中ストリクチニン濃度とオリ形成の相関性１）
１４種類の茶葉（静岡産荒茶）のそれぞれについてストリクチニン含有濃度を試験３と同様にＨＰＬＣで測定した。
【００７７】
原料茶葉中のストリクチニン濃度を測定するために、茶のタンニン定量における公定分析法の測定用試料溶液調製法（農林水産省野菜・茶業試験場「茶の分析法」茶業研究報告 第７１号p52（1990））で採用されている「熱水抽出法」によって測定用試料溶液を調製する一方、当該熱水抽出法を酸性熱水抽出に変更した「酸性熱水抽出法（本発明独自の方法）」によっても測定用試料溶液を調製した。
【００７８】
熱水抽出法では、緑茶のミル粉砕物０．５ｇを１００ｍｌメスフラスコに秤量し、これを、沸騰イオン交換水約８０ｍｌ（ｐＨ５．９）で１０分間、３分毎に攪拌しながら抽出して「熱水抽出液」を得た。
【００７９】
他方、酸性熱水抽出法では、緑茶のミル粉砕物０．５ｇを１００ｍｌメスフラスコに秤量し、この緑茶粉砕物を沸騰イオン交換水に０．１％リン酸を添加した水溶液約８０ｍｌ（ｐＨ２．０）で１０分間、３分毎に攪拌しながら抽出して「酸性抽出液」を得た。
【００８０】
そして、「熱水抽出液」「酸性抽出液」をそれぞれ冷却し、「熱水抽出液」にはイオン交換水（ｐＨ５．９）を加え、「酸性抽出液」には前記リン酸添加水溶液を加え、それぞれ全量を１００ｍｌとし、これをフィルター（アドバンテック社製Ｎｏ．２フィルター使用）で濾過した後、試験３と同様にＨＰＬＣでストリクチニン濃度を測定した。結果は下記表９に示す。
【００８１】
また、上記の各茶葉（静岡産荒茶）２０ｇを、それぞれ７０℃、８００ｍｌのイオン交換水（ｐＨ５．９）に添加し、攪拌した後１分毎に攪拌しながら３．５分間抽出を行い、得られた抽出液をメッシュ（１５０メッシュ）で濾過し、室温まで急冷した後ネル濾過（５０μｍ）した。この抽出液にアスコルビン酸０．４ｇを添加し、これを７０００ｒｐｍで１０分間遠心分離し、上清を微細濾過（アドバンテック社製１μｍMF膜）し、アスコルビン酸を加えてイオン交換水と重曹とによりアスコルビン酸５００ｐｐｍ、ｐＨ６．０、Ｂｒｉｘ０．１（茶固形量換算０．０３）〜０．３（茶固形量換算０．２３）に調製し、この調合液中のストリクチニン濃度を試験３と同様にＨＰＬＣで測定した。
そして更に、オリ観察用に上記調合液を９７℃まで加熱して耐熱広口ビンに充填した後、急冷し、１２１℃、７分の条件でレトルト殺菌を行い、冷却後に３７℃で保管し、経時変化を観察した。結果は下記表９〜表１１、図４及び図５に示した。
【００８２】
なお、表９中の茶固形量中のストリクチニン固形量比とは、調合液中の全茶固形分に対するストリクチニンの含有割合（％）を示した値である。
表１０は、表９のデータを熱水抽出による茶葉中ストリクチニン濃度が高い順に並べ替えた表であり、表１１は、表９のデータを酸性抽出による茶葉中ストリクチニン濃度が高い順に並べ替えた表である。
図４は、横軸：熱水抽出による茶葉中ストリクチニン濃度（重量％）、縦軸：Ｂｒｉｘ０．３（茶固形量換算０．２３）に調製した場合の調合液中ストリクチニン濃度（ｐｐｍ）からなる座標上に二次オリ発生の有無をプロットしたグラフである。
図５は、横軸：酸性抽出による茶葉中ストリクチニン濃度（重量％）、縦軸：Ｂｒｉｘ０．３（茶固形量換算０．２３）に調製した場合の調合液中ストリクチニン濃度（ｐｐｍ）からなる座標上に二次オリ発生の有無をプロットした図である。
【００８３】
【表９】

【００８４】
【表１０】

【００８５】
【表１１】

【００８６】
茶のタンニン定量の公定法で採用されている熱水抽出法ではストリクチニンの抽出量が少なかったが、酸性熱水抽出法によればストリクチニンの抽出量を有効に増加させることができた。しかも、図４及び図５を見ると明らかなように、酸性熱水抽出法による方が二次オリ発生との相関がより一層大きいことが判明した。このような点からすると、原料茶葉中のストリクチニン含有濃度の測定には、酸性熱水抽出法、好ましくはｐＨ２〜４、７０〜１００℃で行う酸性熱水抽出法を採用するのが好ましいと考えることができる。
【００８７】
表１０及び図４を見ると、熱水抽出法によって測定した茶中ストリクチニン含有濃度が０．１４％以下であれば二次オリをほとんど発生せず、更に茶中ストリクチニン含有濃度が０．１０％以下になると二次オリを全く生じないことが分かった。
表１１及び図５より、酸性抽出法によって測定した茶中ストリクチニン含有濃度が０．４３％以下であれば二次オリをほとんど発生せず、更に茶中ストリクチニン含有濃度が０．３７％以下になると二次オリを全く生じないことが分かった。
【００８８】
表１１より、調合液中のストリクチニン含有量が６ｐｐｍ以下、より確実には５ppm以下であれば二次オリが発生しないことが判明した。
茶固形分に対するストリクチニン含有量比という観点から考察すると、緑茶飲料の場合、調合液濃度（Ｂｒｉｘ）約０．２（茶固形量換算０．１３）〜０．３（茶固形量換算０．２３）が一般的であるから、茶抽出液又は茶調合液中の茶固形分に対するストリクチニン含有量が約０．２〜０．５％、特に約０．２〜０．４％以下となるように管理すれば二次オリの発生を無くすことができる。詳しく言えば、調合液の茶固形分濃度（Ｂｒｉｘ）によって指標とする茶固形分に対するストリクチニン含有量の上限値を調整するのが好ましく、茶抽出液又は茶調合液の茶固形量換算濃度（Ｂｒｉｘ）が０．２３の場合には０．２７％、０．１８の場合には０．３４％、０．１３の場合には０．４８％を茶固形分に対するストリクチニン含有量比の上限とするのが好ましい。
【００８９】
試験１２（茶中ストリクチニン濃度とオリ形成の相関性２）
１３種類の中国産釜炒り茶（ジャスミン茶）それぞれについて、ストリクチニン含有濃度を試験３と同様にＨＰＬＣで測定し、各茶葉毎に各段階でのストリクチニン濃度を観察結果と共に下記表１２に示した。
【００９０】
また、上記１３種類の各茶葉（中国産釜炒り茶葉（ジャスミン茶））４０ｇを、それぞれ８０℃、１０００ｍｌのイオン交換水（ｐＨ５．９）に添加し、攪拌した後１分毎に攪拌しながら３．５分間抽出を行い、得られた抽出液をメッシュ（１５０メッシュ）で粗濾過し、室温まで急冷した後ネル濾過（５０μｍ）した。
これを７０００ｒｐｍで１０分間遠心分離し、上清を微細濾過（アドバンテック社製１μｍMF膜）し、アスコルビン酸を加えてイオン交換水と重曹とによりアスコルビン酸５００ｐｐｍ、ｐＨ６．０、Ｂｒｉｘ０．１（茶固形量換算０．０３）〜０．３（茶固形量換算０．２３）に調製し、この調合液中のストリクチニン濃度を試験３と同様にＨＰＬＣで測定した。
そして更に、オリ観察用に調合液を９７℃まで加熱して耐熱広口ビンに充填した後、急冷し、１２１℃、７分の条件でレトルト殺菌を行い、冷却後に３７℃で保管し、経時変化を観察した。結果は下記表１２〜１４、図６及び図７に示した。
【００９１】
なお、表１２中の茶固形量中のストリクチニン固形量比とは、調合液中の全茶固形分に対するストリクチニンの含有割合（％）を示した値である。
表１３は、表１２のデータを熱水抽出による茶葉中ストリクチニン濃度が高い順に並べ替えた表であり、表１４は、表１２のデータを酸性抽出による茶葉中ストリクチニン濃度が高い順に並べ替えた表である。
図６は、横軸：熱水抽出による茶葉中ストリクチニン濃度（重量％）、縦軸：Ｂｒｉｘ０．３（茶固形量換算０．２３）に調製した場合の調合液中ストリクチニン濃度（ｐｐｍ）からなる座標上にオリ発生の有無をプロットしたグラフである。
図７は、横軸：酸性抽出による茶葉中ストリクチニン濃度（重量％）、縦軸：Ｂｒｉｘ０．３（茶固形量換算０．２３）に調製した場合の調合液中ストリクチニン濃度（ｐｐｍ）からなる座標上にオリ発生の有無をプロットした図である。
【００９２】
【表１２】

【００９３】
【表１３】

【００９４】
【表１４】

【００９５】
この結果、ジャスミン茶の場合も、茶のタンニン定量の公定法で採用されている熱水抽出法ではストリクチニンの抽出量が少なかったが、酸性熱水抽出法によればストリクチニンの抽出量を有効に増加させることができた。しかも、酸性熱水抽出法による方が二次オリ発生との相関がより一層大きいことが判明した。このような点からすると、ジャスミン茶の場合においても、原料茶葉中のストリクチニン含有濃度の測定は酸性熱水抽出法、例えばｐＨ約４．５以下、約６０〜１００℃、約５〜６０分間、好ましくはｐＨ２．０〜４．０、７０〜１００℃の酸性熱水で、１０〜３０分間抽出を行う酸性熱水抽出法を採用するのが好ましいと考えることができる。
【００９６】
表１３及び図６を見ると、熱水抽出法によって測定した茶中ストリクチニン含有濃度が０．４９％以下であれば二次オリをほとんど発生せず、更に茶中ストリクチニン含有濃度が０．３３％以下になると二次オリを全く生じないことが分かった。
表１４及び図７より、酸性抽出法によって測定した茶中ストリクチニン含有濃度が０．９０％以下であれば二次オリをほとんど発生せず、更に茶中ストリクチニン含有濃度が０．６１％以下になると二次オリを全く生じないことが分かった。
【００９７】
表１４より、調合液中のストリクチニン含有量が１４ｐｐｍ以下、より確実には１３ppm以下であれば二次オリが発生しないことが判明した。
茶固形分に対するストリクチニン含有量比という観点から考察すると、ジャスミン茶飲料の場合、調合液濃度（Ｂｒｉｘ）約０．２（茶固形量換算０．１３）〜０．３（茶固形量換算０．２３）が一般的であるから、茶抽出液又は茶調合液中の茶固形分に対するストリクチニン含有量が約０．５〜１．１％、特に約０．６〜０．８％以下となるように管理すれば二次オリの発生を無くすことができる。詳しく言えば、調合液の茶固形分濃度（Ｂｒｉｘ）によって指標とする茶固形分に対するストリクチニン含有量の上限値を調整するのが好ましい。茶抽出液又は茶調合液の茶固形量換算濃度（Ｂｒｉｘ）が０．２３の場合には０．６２％、０．１８の場合には０．８０％、０．１３の場合には１．１１％を茶固形分に対するストリクチニン含有量比の上限とするのが好ましい。
【図面の簡単な説明】
【図１】 試験２（オリの成分分析試験）の作業手順の概略を示した図である。
【図２】 試験４（ストリクチニンの加熱分解試験）において、精製ストリクチニン溶液をレトルト殺菌に供し、「加熱殺菌前調製液」及び「加熱殺菌後調製液」のストリクチニン含有量及びエラグ酸含有量をＨＰＬＣで測定した結果を示すグラフである。
【図３】 試験４（ストリクチニンの加熱分解試験）において、試験１で得た「HP-20非吸着画分」に精製ストリクチニンを添加した調製液をレトルト殺菌に供し、「加熱殺菌前調製液」及び「加熱殺菌後調製液」のストリクチニン含有量及びエラグ酸含有量をＨＰＬＣで測定した結果を示すグラフである。
【図４】 試験１１（茶葉中ストリクチニン濃度とオリ形成の相関性１）において、横軸：熱水抽出による茶葉中ストリクチニン濃度（重量％）、縦軸：Ｂｒｉｘ０．３（茶固形量換算０．２３）に調製した場合の調合液中ストリクチニン濃度（ｐｐｍ）からなる座標上にオリ発生の有無をプロットしたグラフである。
【図５】 試験１１において、横軸：酸性抽出による茶葉中ストリクチニン濃度（重量％）、縦軸：Ｂｒｉｘ０．３（茶固形量換算０．２３）に調製した場合の調合液中ストリクチニン濃度（ｐｐｍ）からなる座標上にオリ発生の有無をプロットしたグラフである。
【図６】 試験１２（茶葉中ストリクチニン濃度とオリ形成の相関性２）において、横軸：熱水抽出による茶葉中ストリクチニン濃度（重量％）、縦軸：Ｂｒｉｘ０．３（茶固形量換算０．２３）に調製した場合の調合液中ストリクチニン濃度（ｐｐｍ）からなる座標上にオリ発生の有無をプロットしたグラフである。
【図７】 試験１２において、横軸：酸性抽出による茶葉中ストリクチニン濃度（重量％）、縦軸：Ｂｒｉｘ０．３（茶固形量換算０．２３）に調製した場合の調合液中ストリクチニン濃度（ｐｐｍ）からなる座標上にオリ発生の有無をプロットしたグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for selecting a raw material for tea beverages that is suitable for producing a tea beverage that does not generate orientation even when stored for a long period of time.
[0002]
[Prior art]
Recently, tea beverages that are sealed and filled in cans, plastic containers, etc. have been commercialized one after another, but selection of the raw tea used for such tea beverages has conventionally been made by extracting tea leaves. In general, the selection was made based on sensory inspection and quality evaluation by a near infrared spectrophotometer.
[0003]
By the way, tea beverages have a problem that a flock-like, floating or cloudy suspension / precipitate, that is, a so-called “ori” is generated during storage. In the case of stuffed tea beverages, the commercial value is also lost visually.
[0004]
Generally speaking, “ori” can be divided into “primary ori” that starts to precipitate immediately after beverage production and “secondary ori” that occurs over time during storage after beverage production. Of these, “primary ori” has already been clarified to be produced by the combination of caffeine and tannin, protein, etc., and the prevention method is also applied to diatomite filtration and membrane filtration after centrifuging the tea extract. It has been confirmed that it can be reliably prevented by applying.
[0005]
However, there are various opinions regarding the mechanism of “secondary orientation”, and there is no established opinion yet. For example, the following were known as major views.
[0006]
That is, “When green tea is extracted, it initially contains a high concentration of flavonols in an unoxidized state. This flavonol (especially the catechin component) contains calcium, magnesium, aluminum, zinc and iron in the extract. It is gradually oxidized by metal ions and dissolved oxygen to become high-molecular polyphenols, and these oxidized polyphenols combine with caffeine, proteins, pectin, polysaccharides, etc. by the catalytic action of metal ions over time to form a complex. With the formation of this complex, green tea turns from transparent light green to brown and gradually begins to suspend, eventually forming a visible floc-like secondary orientation. " .
[0007]
In addition, the “tea beverage production method” conventionally proposed for the purpose of preventing the occurrence of secondary orientation has been roughly classified into the following four categories a) to d).
[0008]
a) A method of removing the causative agent of the orientation by filtration such as ultrafiltration, microfiltration, diatomaceous earth filtration,
b) At that time, before the filtration, ascorbic acid, baking soda and the like are added or the causative agent of the sediment is positively precipitated by rapid cooling, followed by filtration,
c) a method of solubilizing or stabilizing an insoluble complex by adding a chemical agent or an enzyme reagent,
d) A method of adsorbing and removing metal ions in the tea extract by ion exchange treatment.
[0009]
a) As a method for removing the causative agent of oli by filtration such as ultrafiltration, microfiltration, and diatomaceous earth filtration, for example, a tea extract is prepared at a liquid temperature of 5 to 15 ° C., and an ultrafiltration membrane (molecular weight of 1 to 100,000) to remove tea cream (Japanese Patent Laid-Open No. Sho 63-36745), and water-soluble tea components obtained by extracting green tea or fresh or dried tea leaves by ultrafiltration For example, a method for producing a clear green tea beverage by fractionating and substantially removing a polymer component having a molecular weight of about 10,000 or more (JP-A-4-45744) is disclosed.
[0010]
b) As a method of positively precipitating the causative agent of the olivine and filtering it, for example, ascorbic acid is added to the extract from which green tea is extracted to make it acidic, and then rapidly cooled and centrifuged, and then diatomaceous earth filtration is performed. The method of clarification is performed (Japanese Patent Publication No. 7-97965), the tea is extracted with warm water, the resulting extract is cooled, tannic acid is added and the mixture is allowed to stand, and then fine tea particles are removed by centrifugation or the like. Thereafter, clarification by diatomaceous earth filtration (Japanese Patent Laid-Open No. 6-269246), a method of adding tea ascorbate to a stock solution from which tea leaves are extracted, and further producing a tea beverage by a cross flow method using a microfiltration membrane (Japanese Patent Laid-Open No. 11-56241), adding chitosan to water-soluble tea component of green tea, adsorbing high molecular polyphenols, adsorbing adsorbed chitosan and the remaining chitosan by diatomaceous earth And a method of eliminating the crystallized precipitate (Japanese Patent Laid-Open No. 6-311847) discloses by yield.
[0011]
c) As a method for solubilizing or stabilizing the insoluble complex by adding a chemical agent or an enzyme reagent, for example, the hot water extract of green tea is centrifuged or filtered, and an enzyme having hemicellulase activity is added. A method of effectively suppressing secondary precipitation of green tea beverages by combining the processing steps (Japanese Patent Laid-Open No. 8-228684), and adding α-amylase to the green tea extract to suppress the occurrence of flocs in the beverage In addition to US Pat. No. 4,501,261 (Jongeling) and the like.
[0012]
d) As a method of adsorbing and removing metal ions in tea extract by ion exchange treatment, for example, hot water or hot water extract of tea leaves is obtained by using a cation exchange resin having a sulfonic acid group to which potassium ions are bound in advance. A tea production method (Patent No. 3152416) characterized by cation exchange treatment is disclosed.
[0013]
[Problems to be solved by the invention]
Of the methods for producing tea beverages that have been proposed in the past, the main ones were actually tested, and all of them exhibited their effects, but many methods differed from the raw tea leaves shown in the examples. When the (production area or plucking time) is used, or when the concentration of the beverage is made higher than that of the embodiment in balance with the flavor, “secondary orientation” may occur.
[0014]
In addition, in order to confirm whether or not the produced tea beverage generates secondary orientation, conventionally, the produced tea beverage is stored for a long period of time (for example, 6 months) at room temperature or under heating conditions, and during that time, the secondary orientation is preserved. It was necessary to continuously observe the occurrence of this. For this reason, if the occurrence of secondary orientation was observed, it was necessary to go back to the selection of raw materials and the setting of manufacturing conditions and perform the test again, which required a lot of labor and time.
Moreover, even for the same type of tea leaves, secondary ori may or may not occur if the production area or plucking time is different, in order to produce a stable quality tea beverage that does not generate secondary ori Required repeated testing and strict manufacturing controls.
[0015]
Therefore, the present invention investigates the cause of the secondary orientation and advances the research on the relationship between the secondary orientation and the raw tea, and provides a new raw tea selection method based on the new knowledge obtained as a result. To do.
[0016]
[Means for Solving the Problems]
As a result of research, the present inventor has found that 1) “striketinin” in tea extract or tea preparation is decomposed into “ellagic acid” by heat sterilization, and this “ellagic acid” is combined with “protein” and the like. Form the next orientation. 2) The concentration of strictinin in tea leaves varies depending on the variety, origin, picking time, picking method, and cultivation method of the raw tea, and there is a close correlation between the strictinin content of the raw tea and the secondary orientation. That there is. The present invention has been conceived based on such knowledge.
[0017]
“Strichtinin” is a substance represented by the following chemical formula (1-O-galloyl-4,6-O- (S) -hexahydroxydiphenoyl-β-D-glucose), which is tannin extracted from tea. It is a kind of ellagitannins ("Casuariin, Stachyurin and Strictinin, new Ellagitannins from Casuarina Stricta and Stachyurus Praecox", Chem. Pharm. Bull. 30 (2) 766-769 (1982)).
It should be noted that strictinin is a tea extraction component that is also attracting attention as an antiallergic component (Chunichi Shimbun, published on July 8, 2001). For the extraction and purification method of strictinin, tea leaves are extracted with hot water, The obtained extract is fractionally extracted with acetone and water, and the acetone phase is separated by liquid chromatography or the like (“Casuariin, Stachyurin and Strictinin, new Ellagitannins from Casuarina Stricta and Stachyurus Praecox”, Chem. Pharm Bull. 30 (2) 766-769 (1982)), and tea leaves are extracted with hot water, and the resulting extract is separated and extracted with ethyl acetate and water, and the aqueous phase is separated by liquid chromatography or the like. ("Tannins of Casuarina and Stachyurus Species. Part1. Structures of Pendunculagin, Casuaricin Strictinin,, Casuarinin, Casuarin, and Stachyurin", J.CHEM. SOC. PERKIN TRNS.I No.8 1765-1772 (1983) ) Etc. were known.
[0018]
[Chemical 1]

[0019]
The method for selecting a raw material for tea beverage proposed by the present invention is a method of selecting raw tea using the strictinin-containing concentration in tea leaves as an index. That is, in the stage of selecting a raw material for tea beverage, the strictinin-containing concentration in tea leaves is measured, and the raw tea is selected on the basis that the strictinin-containing concentration does not exceed a predetermined value.
[0020]
As described above, in the past, a tea beverage was actually made from raw tea selected based on sensory tests and quality evaluation by a near-infrared spectrophotometer, and if it was stored for a long period of time and was not continuously observed, tea beverage Could not confirm whether or not will generate secondary orientation. Moreover, even if it is the same kind of tea leaves, secondary ori may or may not occur, so it has been difficult to stably produce a tea beverage that does not generate secondary ori.
On the other hand, according to the present invention, it is possible to predict the occurrence of secondary orientation only by measuring the strictinin-containing concentration of the raw tea, and only selecting the raw tea using the strictinin-containing concentration as an index. Raw material tea that does not produce secondary orientation can be selected.
[0021]
In the present invention, “raw material for tea beverage” or “raw material tea” means tea (including leaves and stems) as a raw material for producing a tea beverage, and includes fresh tea leaves, crude tea, and finishing. It is meant to include any tea.
Further, in the present invention, “secondary orientation” does not include precipitation of fine powder and is intended to be a flock-like (cotton-like) suspension / precipitation, and should be distinguished from “primary orientation”. .
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0023]
(Ingredient tea targeted by the present invention)
“Tea” to be selected by the present invention is not limited to its variety, place of production, harvesting time, plucking method, cultivation method, etc., as long as it is a leaf or stem plucked from tea tree (scientific name: Camellia sinensis) Also includes tea seeds. Raw tea leaves (including leaves and stems) can be used as raw tea. In addition, if it is rough tea that has been subjected to rough tea processing that stops enzyme activity by means such as steaming or frying these raw tea leaves etc., sencha, kettle stir-fried tea, kabuse tea, gyokuro, tencha, matcha, Any kind of bancha, roasted tea, steamed ball green tea, kettle roasted ball green tea, etc. can be used as the raw tea. Two or more kinds of these non-fermented teas may be combined, or may be prepared by adding a fragrance. In addition, weakly fermented teas such as jasmine tea can also be targeted. In addition, even if it is called jasmine tea, it is preferable to classify what is made by putting an artificial fragrance into green tea as non-fermented tea.
However, semi-fermented tea such as oolong tea, fermented tea such as black tea, and post-fermented tea such as puer tea are not included. The cream down that occurs in Oolong tea and black tea is due to a different cause from the irreversible flock-like orientation (ie secondary orientation) that occurs in green tea and the like.
Moreover, as finishing tea, as long as the above-mentioned rough tea is subjected to currently known finishing processing, any tea can be used.
[0024]
It should be noted that different varieties of tea leaves, production area, picking time, picking method, cultivation method, etc., the concentration of strictinin in tea leaves will be different, and even in the same kind of tea (Camellia sinensis), the tea season and ripeness will increase. In other words, the inventor has confirmed that the concentration of strictinin tends to decrease as the amount of tea leaf fiber increases.
[0025]
(Measurement method of strictinine content in tea leaves)
Since strictinin is a kind of tannin, the official analysis method in the tannin determination method or catechin determination method of tea (the Ministry of Agriculture, Forestry and Fisheries Vegetable and Tea Experiment Station "Tea Analysis Method" It is preferably measured according to Research Report No. 71 (1990).
However, as a result of various tests conducted by the inventor, it is better to extract tea using hot acid water than hot water extraction according to the measurement sample solution preparation method defined in the official analysis method. It was found that strictinin can be easily extracted from tea leaves in a large amount, and that the strictinin-containing concentration of the extract obtained by acidic hot water extraction has a higher correlation with the occurrence of secondary orientation.
Therefore, in the present invention, as a method for measuring the concentration of strictinine in tea leaves, a method based on a measurement sample solution preparation method defined by an official analysis method, that is, tea leaves are extracted with hot water, and strictinin in the resulting extract is obtained. “Hot water extraction method” for measuring the content concentration, and a method in which hot water extraction in the hot water extraction method is replaced with acidic hot water extraction, that is, tea leaves are extracted with acidic hot water, and strictinin in the resulting extract is obtained. We propose "acid hot water extraction method" to measure the concentration of the content.
[0026]
In the hot water extraction method, tea leaves are extracted with hot water, for example, hot water of about 60 to 100 ° C., preferably 70 to 100 ° C. for about 5 to 60 minutes, preferably 10 to 30 minutes. Official analysis method (HPLC method) in tannin determination method (colorimetric determination method) or catechin determination method of kara tea (Ministry of Agriculture, Forestry and Fisheries Vegetable and Tea Experiment Station "Tea Analysis Method" Tea Industry Research Report No. 71, p52-55 ( It is preferable to prepare a measurement sample solution of 1990)) and measure strictinin. In addition, it can replace with hot water and can also extract with a hydrophilic organic solvent and a hydrous hydrophilic organic solvent.
On the other hand, in the acidic hot water extraction method, the tea leaves are heated with acidic hot water, such as acidic hot water having a pH of about 4.5 or less, about 60-100 ° C., preferably 70-100 ° C., for about 5-60 minutes, preferably 10-30. Extraction for minutes, filtration after cooling, and official analysis method (HPLC method) in the tannin determination method (colorimetric determination method) or catechin determination method of tea from this extract (Ministry of Agriculture, Forestry and Fisheries Vegetable and Tea Experiment Station "Analysis method of tea" It is preferable to prepare a sample solution for measurement according to “Tea industry research report No. 71 p52-55 (1990)) and measure strictinin. In addition, it can replace with acidic hot water, and it can extract by making a hydrophilic organic solvent and a hydrous hydrophilic organic solvent acidic.
[0027]
Specifically, for example, tea (raw tea leaves, rough tea, finished tea) is pulverized with a mill or the like, and the obtained tea leaves (1.0-mm passage) are weighed into a 100 ml volumetric flask. An acid such as phosphoric acid was added thereto to adjust to pH 7 or lower, preferably pH 4.5 or lower, at about 60 to 100 ° C., preferably 70 to 100 ° C. in acidic hot water for about 5 to 60 minutes, as necessary. Extract with stirring. And after cooling the obtained extract to room temperature, ion-exchange water or the above-mentioned phosphoric acid-added ion-exchange water is added to determine the total amount to 100 ml, and this is filtered through a filter, and the resulting filtrate is used as a sample solution for measurement. Is preferable.
[0028]
(Indicator for selection of raw tea)
In order to select a raw tea that is unlikely to cause secondary ori, it is only necessary to select whether or not the measured concentration of strictinin in tea leaves falls within a specified range. Concentration content measured by the method, strictinine concentration measured by the acidic hot water extraction method, strictinine concentration measured by the organic solvent and hydrous organic solvent extraction method, or measured by the organic solvent and hydrous organic solvent acidic extraction method It is preferable to change the standard depending on the strictinin-containing concentration.
[0029]
That is, the concentration of strictinin in the extract obtained by the hot water extraction method Concentration of strictinin in tea leaves determined from the above In the case of non-fermented tea such as green tea, the concentration of strictinin Is 0 . If tea in the range of 14% or less is selected as the raw tea, the possibility of occurrence of secondary orientation can be reduced. Especially, tea in the range of 0.10% or less can be selected to generate secondary orientation. Can be made extremely low. In weakly fermented teas such as jasmine tea, the concentration of strictinin is 0.49% or less If the tea in the range is selected, the possibility of occurrence of secondary orientation can be lowered. Especially, if the tea in the range of 0.33% or less is selected, the possibility of occurrence of secondary orientation is extremely reduced. it can.
[0030]
On the other hand, the concentration of strictinin in the extract obtained by the acidic hot water extraction method Concentration of strictinin in tea leaves determined from the above In the case of non-fermented tea such as green tea, the concentration of strictinin Is 0 . If tea in the range of 43% or less is selected as the raw tea, the possibility of secondary ori can be reduced. Especially, tea in the range of 0.37% or less can be selected to generate secondary ori. Can be made extremely low. In weakly fermented teas such as jasmine tea, the concentration of strictinin Is 0 . If tea in the range of 90% or less is selected, the possibility of occurrence of secondary orientation can be lowered. Especially, if tea in the range of 0.61% or less is selected, possibility of occurrence of secondary orientation is extremely low. can do.
[0031]
(Method for producing tea beverage)
Hereinafter, an example of a method for producing a tea beverage that does not generate secondary orientation using the tea selected as described above will be described.
In addition, although the manufacturing method of a green tea drink is demonstrated here, also in the case of other unfermented tea or weakly fermented teas, such as jasmine tea, tea which does not generate | occur | produce a secondary orientation by using for the manufacturing method currently performed normally. Beverages can be produced.
[0032]
The tea selected as described above is a tea beverage production method currently used, for example, an extraction process for extracting raw tea leaves, a filtration process for filtering the extract, and a formulation for adjusting the concentration and pH of the extract The tea beverage which does not produce a secondary orientation can be manufactured by using for the manufacturing method of the tea beverage provided with the process and the sterilization process which heat-sterilizes a preparation liquid. At this time, it is preferable to manufacture and manage the strictinin content of the tea extract or tea preparation before heat sterilization to about 6 ppm or less, particularly 5 ppm or less. This is because it has been confirmed that secondary orientation is not generated if the strictinin content of the tea extract or tea preparation before heat sterilization is about 5 to 6 ppm or less. In addition, the strictinin content with respect to the tea solid content in the tea extract or tea preparation before heat sterilization is controlled to about 0.2 to 0.5% or less, particularly 0.2 to 0.4% or less. May be. However, the manufacturing method of the tea drink of this invention is not limited to this example.
Hereinafter, each step will be described in detail.
[0033]
“Extraction of tea” is, for example, using an extraction device called a kneader according to a conventional method, 20 to 50 times the amount of raw tea leaves, 0 to 100 ° C. with extracted water for about 1 to 20 minutes, as necessary What is necessary is just to stir 1 to several times and to extract by a normal pressure. However, the extraction method and extraction conditions are not particularly limited, and for example, pressurized extraction may be performed.
Examples of the extraction water used in the extraction include hard water, soft water, ion exchange water, natural water, ascorbic acid-containing aqueous solution, pH adjusted water, and the like. At this time, the content of strictinin in the extract obtained by extraction depends on the pH of the extracted water. Therefore, if the pH of the extracted water is in the acidic region, particularly pH 4.5 or less, the content of strictinin in the extract is large. Become. Therefore, conversely, the strictinin content in the extract can be reduced by increasing the pH of the extract. For example, as a result of measuring the strictinin content of the tea preparation before the heat sterilization process, when the strictinin content exceeds a predetermined value (about 5 to 6 ppm), the pH of the extracted water is set to 5 or more, particularly 6 or more. By doing so, the amount of strictinine extraction can be effectively suppressed. However, the extraction in the weakly acidic region or neutral region is disclosed only as one of the control means for reducing the strictinin-containing concentration in the extract, and in the method for producing a tea beverage according to the present invention, it is disclosed. It is not preferable to extract in the sex region. Moreover, since the deterioration of catechin becomes a problem when the pH of the extracted water is raised, it is preferable to set the upper limit to about pH 6.5 to 7.
Although the extraction temperature, that is, the temperature of the hot water to be extracted, can influence the content of strictinin in the extract, the extraction temperature is generally about 45 to 100 ° C., particularly preferably 60 to 90 ° C.
[0034]
The extract obtained by extraction is cooled to about 5 to 40 ° C. as necessary. Simultaneously or before and after that, ascorbic acid or sodium ascorbate may be added to the extract to make it acidic (pH 4 to 5) as necessary. By cooling or acidic preparation of the extract, it is possible to prevent the extraction component from being oxidized and to precipitate the primary causative component to increase the efficiency of the subsequent centrifugation.
[0035]
In the “filtration step”, for example, rough filtration for removing extraction residues such as tea leaves and large fine powders, and filtration for removing a causative substance of primary sediment are preferably performed. However, it is arbitrary where these rough filtration and primary sediment causative substance removal filtration are inserted in the manufacturing process.
For the coarse filtration, a filtration method that is currently employed for removing flanks, stainless steel filters, strainers and other extraction residues can be arbitrarily employed.
As a filtration method for removing the primary causative substance, there is a method such as diatomaceous earth filtration or appropriate membrane filtration following centrifugation.
Incidentally, the centrifugation may be performed, for example, at a rotational speed of 5000 to 10000 rpm, and it is preferable to cool the extract or the prepared solution to about 5 to 40 ° C. in advance as described above.
In addition, when performing diatomaceous earth filtration, it is not always necessary to insert a centrifugal separator, but by inserting the centrifugal separator in the previous step, the filtration time can be shortened by reducing the burden of diatomaceous earth filtration, for example, increasing the permeate flow rate. .
Examples of membrane filtration include membrane separation such as microfiltration, microfiltration, ultrafiltration, reverse osmosis membrane filtration, electrodialysis, biofunctional membrane, and filtration using a filter aid such as diatomaceous earth filtration. You may make it carry out in combination.
The above-mentioned centrifugation, diatomaceous earth filtration, membrane filtration method and condition setting can be arbitrarily adjusted. In addition, it is not clear how the strictinin content changes when the method of centrifugation, diatomaceous earth filtration and membrane filtration is changed, but the conditions of centrifugation, diatomaceous earth filtration and membrane filtration are not clear. It is preferable to measure the strictinin content by variously changing the method and the condition setting, and use this measurement value as an index to determine the filtration method of centrifuging, diatomaceous earth filtration and membrane filtration, and to perform production management such as condition setting.
[0036]
"Formulation process" is the same as the production method of ordinary tea beverages, water (hard water, soft water, ion exchange water, natural water, etc.), ascorbic acid, sodium ascorbate, baking soda, sugar, dextrin, fragrance, emulsifier, stabilizer Alternatively, any one of other taste raw materials or a combination of two or more of them may be added to adjust pH, concentration, and taste.
In terms of the relationship with the secondary orientation, when the concentration (Brix value) is reduced, the concentration of the partner component (protein etc.) that binds to “ellagic acid” generated by the decomposition of strictinin by heat sterilization can be reduced. Therefore, generation of secondary orientation can be prevented. Therefore, for example, as a result of measuring the strictinin content of the tea preparation liquid before the heat sterilization step, if the strictinine content of the tea preparation liquid exceeds a predetermined value (about 5 to 6 ppm), the concentration of the tea preparation liquid (Brix Reducing the value) is another option for manufacturing management. However, considering the flavor of the tea beverage, the concentration (Brix value) of the tea preparation liquid is preferably set to about 0.1 to 0.4, particularly 0.2 to 0.3.
[0037]
If the “heat sterilization step” is a can beverage, after reheating the preparation liquid obtained in the preparation step as necessary, the preparation liquid is filled and heat sterilization (for example, under appropriate pressure (1.2 mmHg) Etc.) and is sterilized by retort at 121 ° C. for 7 minutes.) In the case of a plastic bottle beverage, UHT sterilization (the prepared solution is held at about 120 to 150 ° C. for 1 to several tens of seconds) is performed. do it.
It is not clear how the content of strictinin changes when the method and conditions of heat sterilization are changed, but at least it is formulated by heat sterilization such as retort sterilization and UHT sterilization currently in progress. It is clear from the following test results that strictinin in the liquid is decomposed into ellagic acid, and that ellagic acid becomes the nucleus of the secondary orientation.
[0038]
Test 1 (precipitation test)
20 g of commercially available green tea (finished tea: “Oi Ocha” made by Itoen Co., Ltd., first picked 1500) was extracted with 800 ml of distilled water (pH 5.9) at 70 ° C. for 3.5 minutes and insoluble by centrifugation (7000 rpm, 10 minutes). The fraction was removed, and the supernatant was passed through a column packed with polystyrene resin (trade name: DIAION HP-20 (manufactured by Mitsubishi Chemical)) to obtain “HP-20 non-adsorbed fraction”. Next, the column was washed with distilled water, eluted with 80% aqueous methanol solution, and concentrated to dryness to obtain “HP-20 adsorbed 80% methanol fraction”.
[0039]
Each fraction obtained above was subjected to a precipitate formation test as follows.
“HP-20 non-adsorbed fraction” was obtained “HP-20 non-adsorbed fraction” Bx0.4, 200 ml, “HP-20 adsorbed 80% methanol fraction” was obtained “HP-20 adsorbed fraction” "80% methanol fraction" 0.5g, "HP-20 non-adsorbed fraction + HP-20 adsorbed 80% methanol fraction" is "HP-20 non-adsorbed fraction" Bx0.4, 200ml "HP- "20 adsorbed 80% methanol fraction" 0.5 g was added, and ascorbic acid 500 ppm, 500 ml, pH 6.0 was prepared using ascorbic acid, baking soda and ion-exchanged water, respectively, and after heat sterilization at 121 ° C for 7 minutes, It was stored at 37 ° C. and observed.
The results of the observation are shown in Table 1 below.
[0040]
[Table 1]

[0041]
The occurrence of secondary orientation (floc precipitate) was observed only in “HP-20 non-adsorbed fraction + HP-20 adsorbed 80% methanol fraction”. From this, it can be considered that each of the “HP-20 non-adsorbed fraction” and the “HP-20 adsorbed 80% methanol fraction” contains at least one component that causes secondary sediment. It was.
[0042]
Test 2 (Ori component analysis test)
An outline of the work procedure of this test is shown in FIG.
20 g of commercially available green tea (finished tea: “Oi Ocha” made by Itoen Co., Ltd., first picked 1500) was extracted with 800 ml of distilled water (pH 5.9) at 70 ° C. for 3.5 minutes and insoluble by centrifugation (7000 rpm, 10 minutes). The fraction was removed, and the supernatant was passed through a column filled with polystyrene resin (trade name: DIAION HP-20 (manufactured by Mitsubishi Chemical)). Then, the column was washed with distilled water, and then 20%, 40% , 60%, 80%, 100% methanol aqueous solution stepwise.
[0043]
Each of the obtained fractions was added to “HP-20 non-adsorbed fraction” (Brix 0.4) in the same manner as in Test 1, and a precipitate formation test was performed. As a result, “HP-20 adsorbed 20% methanol fraction” And “HP-20 adsorbed 40% methanol fraction” was confirmed to generate secondary sediment (floc precipitate). In particular, the amount produced in the “HP-20 adsorption 20% methanol fraction” was large.
[0044]
Therefore, after concentrating and drying the “HP-20 adsorption 20% methanol fraction”, it was passed through a column filled with ODS (: reverse phase resin (trade name: Cosmo Seal 75C18OPN (manufactured by Nacalai Tesque)), and then distilled. The column was washed with water and then eluted stepwise with 10%, 20%, and 30% aqueous methanol.
[0045]
Each of the obtained fractions was subjected to the same precipitation formation test as that of the HP-20 fraction. As a result, the amount of precipitate produced in the “ODS-adsorbed 10% methanol fraction” was large. Fractions "were further collected by high performance liquid chromatography (HPLC: LC-908 Recycling Preparative HPLC (JAPAN ANALYTICAL INDUSTRY CO.LTD)) using a reverse phase column (Wakosil-II5C18HG Prep), and methanol: water: A similar precipitate formation test was further performed on each of the six peaks obtained with a solvent consisting of acetic acid = 22: 78: 0.1.
[0046]
As a result, precipitation was observed in “Peak 3”, and “Peak 3” was identified by LC-MS and NMR, and found to be strictinin.
The “HP-20-adsorbed 40% methanol fraction” was also tested in the same manner as described above. As a result, strictinin was still contained. It was also found that components other than strictinin in this fraction were not involved in precipitation formation.
[0047]
Test 3 (beverage processing characteristics of strictinin)
2. Add 20 g of commercially available green tea (finished tea: “Ooicha” highland first picking 1500 made by ITO EN Co., Ltd. 1500) to 800 ° C. ion-exchanged water (pH 5.9) at 70 ° C. and stir every minute for 3 minutes. Extracted for 5 minutes. Thereafter, the mixture was roughly filtered with a mesh (150 mesh), cooled to room temperature, and filtered with a nell (50 μm). 0.4 g of ascorbic acid was added to the obtained extract, and after centrifugation at 7000 rpm for 10 minutes, the supernatant was finely filtered (1 μm MF membrane manufactured by Advantech), and 0.6 g of ascorbic acid was further added to the filtrate. Using the exchange water and baking soda, it adjusted to Brix0.3 and pH6.0, and the "preparation liquid before heat sterilization" was obtained.
This “prepared solution before heat sterilization” was heated to 97 ° C., filled into cans, rapidly cooled and then subjected to retort sterilization at 121 ° C. for 7 minutes and then cooled to obtain “prepared solution after heat sterilization”.
The obtained “preparation liquid before heat sterilization” and “preparation liquid after heat sterilization” were stirred and treated with a 0.45 μm filter, and then subjected to high performance liquid chromatography (HPLC) under the following conditions (HPLC conditions / Table 2). The strictinin concentration was measured.
[0048]
(HPLC conditions)
Equipment: Hitachi D-7000 Advanced HPLC, D-7000 Advanced HPLC System Manager
Column: Wakosil-II5C18HG φ4.6 × (30 + 250) mm
Column temperature: 40 ° C
Flow rate: 0.6 ml / min
Detection: UV280
Mobile phase A: 15% MetOH (0.1% phosphoric acid)
Mobile phase B: 45% MetOH (0.1% phosphoric acid)
[0049]
[Table 2]

[0050]
The sample was injected by 5 μL, and the peak appearing in the vicinity of 19 min was quantified by the absolute calibration curve method using strictinin extracted and purified in Test 2 as a standard. The results are shown in Table 3 below.
[0051]
[Table 3]

[0052]
From this result, it was considered that strictinin was decomposed or precipitated by heat sterilization. In addition, since strictinin in beverages is almost completely decomposed by heat sterilization generally performed in the production process of tea beverages (some of them were not decomposed in the case of UHT sterilization), they are usually marketed. The tea drinks found to contain almost no strictinin.
[0053]
Test 4 (thermal decomposition test of strictinin)
Purified strictinin 5 mg and ascorbic acid 250 mg were dissolved in ion-exchanged water, adjusted to pH 6.0 and 500 ml using ion-exchanged water and sodium bicarbonate, and this prepared solution was subjected to retort sterilization at 121 ° C. for 7 minutes.
Each of the “prepared solution before heat sterilization” and the “prepared solution after heat sterilization” was subjected to high performance liquid chromatography (HPLC) as in Test 3, and a peak appeared in the vicinity of 40 minutes. When this peak was identified by LC-MS and NMR, it was found to be ellagic acid. The results are shown in FIG.
As a result, it was possible to obtain a result that ellagic acid was produced when strictinin was sterilized by retort.
[0054]
In addition, 5 mg of purified strictinin was added to 200 ml of “HP-20 non-adsorbed fraction” (Brix 0.4) obtained in Test 1, and after adjusting the pH to 6.0 and 500 ml using ion-exchanged water and sodium bicarbonate, The prepared solution was subjected to retort sterilization at 121 ° C. for 7 minutes, and strictinin and ellagic acid were measured by HPLC for each of the “prepared solution before heat sterilization” and the “prepared solution after heat sterilization” as described above. The result is shown in FIG. However, in this case, ellagic acid was hardly detected in the “prepared solution after heat sterilization”. From this, when tea beverage is heat sterilized, strictinin in the beverage decomposes to produce ellagic acid, and this ellagic acid is combined with the components contained in the “HP-20 non-adsorbed fraction” to precipitate, that is, secondary ori Could be thought of as forming.
[0055]
Test 5 (extraction pH comparison test)
The amount of strictinin extracted when tea was extracted with an acidic aqueous solution or a basic aqueous solution was compared.
[0056]
70 ° C., 800 ml of ion-exchanged water (pH 5.9), acidic aqueous solution or basic aqueous solution is prepared, and 20 g of commercially available green tea (finished tea: “Oi Ocha”, highland first picking 1500 made by ITO EN) is added thereto, After stirring, extraction was performed for 3.5 minutes with stirring every minute. Thereafter, the mixture was roughly filtered with a mesh (150 mesh), cooled to room temperature, and filtered with a nell (50 μm). Ascorbic acid 0.5 g was added to the obtained basic extract and ion-exchanged water extract, and the acidic extract was centrifuged at 7000 rpm for 10 minutes with no addition, and the supernatant was microfiltered (1 μm MF manufactured by Advantech). Membrane), 0.5 g of ascorbic acid was added to the filtrate, and a final liquid volume of 2000 ml was prepared using ion-exchanged water to obtain a liquid preparation. The strictinine concentration of the liquid preparation was determined by HPLC in the same manner as in Test 3. (Table 4).
[0057]
The acidic aqueous solution was adjusted to pH 3.4 by adding 0.5 g of ascorbic acid to 800 ml of ion-exchanged water (pH 5.9), and the basic aqueous solution was adjusted to 0.5 ml of sodium bicarbonate in 800 ml of ion-exchanged water (pH 5.9). 5 g was added to adjust to pH 8.5.
[0058]
[Table 4]

[0059]
As a result, it was found that the amount of strictinine extracted was increased by acidic extraction.
[0060]
Test 6 (Comparison of the amount of strictinine extracted by acidic extraction)
Ascorbic acid 0.5g was added to 800 ml of ion-exchanged water (pH 5.9) to adjust the pH to 3.4, followed by extraction at 90 ° C, 70 ° C, 50 ° C, and 30 ° C for 10 minutes. A similarly prepared preparation was obtained, and the strictinin concentration of the preparation was determined by HPLC in the same manner as in Test 3 (Table 5).
[0061]
[Table 5]

[0062]
As a result, it was found that the amount of strictinin extracted was large at 70 ° C. or higher.
[0063]
Test 7 (Comparison of extraction time)
Add 0.5g of ascorbic acid to 800ml of ion-exchanged water (pH 5.9) to obtain pH 3.4, extract time 3 minutes, 5 minutes or 20 minutes, and obtain a liquid mixture prepared in the same manner as the acidic aqueous solution in Test 5. The strictinin concentration of the preparation was determined by HPLC in the same manner as in Test 3 (Table 6).
[0064]
[Table 6]

[0065]
The difference between the extraction at 70 ° C. for 10 minutes shown in Test 6 and the extraction at 70 ° C. for 20 minutes shown in Test 7 was not found in the comparison of the strictinin concentration. Therefore, in order to increase the amount of strictinine extracted from Test 5 to Test 7, it is considered preferable to extract with an acidic aqueous solution of 70 ° C. or higher and pH 4.5 or lower for 5 minutes or longer.
[0066]
Test 8 (Elagic acid addition test)
Ellagic acid was added to the “HP-20 non-adsorbed fraction” obtained in Test 1 to confirm the formation of precipitates.
[0067]
2.1 mg of commercially available ellagic acid (manufactured by Sigma) and 250 mg of ascorbic acid were added to 200 ml of the “HP-20 non-adsorbed fraction” (Brix 0.4) obtained in Test 1, and the pH was adjusted to 6 using ion-exchanged water and sodium bicarbonate. The prepared solution was subjected to retort sterilization at 121 ° C. for 7 minutes, and the obtained “ellagic acid + HP-20 non-adsorbed fraction” solution was stored at 37 ° C., and the change with time was observed.
In addition, 2.1 mg of commercially available ellagic acid (manufactured by Sigma) and 250 mg of ascorbic acid were added to ion-exchanged water, adjusted to pH 6.0, 500 ml using ion-exchanged water and sodium bicarbonate, The solution was subjected to retort sterilization for 7 minutes, and the resulting “ellagic acid only” solution was observed in the same manner as described above.
The results are shown in Table 7 below.
[0068]
[Table 7]

[0069]
Considering the above test results together, strictinin in tea extract is decomposed by heat sterilization to produce ellagic acid, which binds to the components contained in “HP-20 non-adsorbed fraction” As a result, it was clarified that floc-like precipitates, that is, secondary olis, were produced in tea beverages.
[0070]
Test 9 (Analysis of components involved in precipitation in “HP-20 non-adsorbed fraction”)
The floc-like precipitate (ori) produced | generated with the tea drink was processed with hydrochloric acid-methanol, the ellagic acid contained in the said precipitate was dissolved, and the component analysis of the said precipitate was performed.
[0071]
The tea beverage produced by the method of Test 1 (“HP-20 non-adsorbed fraction + HP-20 adsorbed 80% methanol fraction”) was stored at 37 ° C. for 5 days to produce a precipitate, and MSfilter (0. 45 μm) was used to collect the precipitate. Next, the filter was washed with methanol and centrifuged to collect a precipitate. Further, the precipitate was washed with 1% hydrochloric acid-methanol, centrifuged again and air-dried, and then used as a sample for SDS-PAGE.
[0072]
As a result of analyzing the components contained in the precipitate by SDS-PAGE, it was found that the precipitate contained a large amount of protein. Moreover, when the saccharide | sugar analysis in the said deposit was performed, saccharide | sugar was hardly detected.
[0073]
Test 10 (model test using amino acids and proteins)
Into a test tube, 1 mg of ellagic acid, each amino acid preparation (manufactured by Kyowa Hakko Co., Ltd.) and bovine serum albimine (manufactured by Sigma Co., Ltd.) shown in Table 8 below were added in the amounts shown in Table 8, respectively, and ion-exchanged water was added. 10 ml. Then, it heat-sterilized at 121 degreeC for 15 minutes, and stored and observed at room temperature.
Further, a control (10 mg of ellagic acid added with 10 ml of ion-exchanged water dissolved) was similarly observed by sterilization and storage.
[0074]
[Table 8]

[0075]
When each amino acid sample was stored at room temperature for 18 days, a floc-like precipitate was observed.
The bovine serum albimine-added solution before heat sterilization did not produce a floc-like precipitate, but the heat-sterilized solution showed formation of a flock-like precipitate.
From the above results, substances that bind to ellagic acid to form a floc-like precipitate (secondary orientation) are amino acids, peptides, and proteins, and these components are denatured by heat treatment or long-term storage, and thus floc-like precipitates. It could be considered to form a precipitate.
[0076]
Test 11 (Correlation 1 between strictinin concentration in tea and orientation formation)
For each of the 14 types of tea leaves (Shizuoka crude tea), the strictinin-containing concentration was measured by HPLC as in Test 3.
[0077]
In order to measure the strictinin concentration in the raw tea leaves, preparation of sample solution for measurement of official analysis method for tea tannin determination (Ministry of Agriculture, Forestry and Fisheries Vegetable and Tea Experiment Station "Analysis Method of Tea" Tea Industry Research Report No. 71 p52 The sample solution for measurement was prepared by the “hot water extraction method” adopted in (1990)), while the hot water extraction method was changed to acidic hot water extraction. The sample solution for measurement was also prepared by “)”.
[0078]
In the hot water extraction method, 0.5 g of green tea mill pulverized product was weighed into a 100 ml volumetric flask and extracted with about 80 ml of boiling ion exchange water (pH 5.9) for 10 minutes with stirring every 3 minutes. A “hot water extract” was obtained.
[0079]
On the other hand, in the acidic hot water extraction method, 0.5 g of green tea mill pulverized product is weighed into a 100 ml volumetric flask, and this green tea pulverized product is added to boiling ion exchange water with about 80 ml of an aqueous solution containing 0.1% phosphoric acid (pH 2. The mixture was extracted with stirring every 3 minutes for 10 minutes to obtain an “acidic extract”.
[0080]
Then, the “hot water extract” and the “acid extract” are cooled, respectively, ion-exchanged water (pH 5.9) is added to the “hot water extract”, and the phosphoric acid-added aqueous solution is added to the “acid extract”. In addition, the total amount was 100 ml, and each was filtered through a filter (using Advantech No. 2 filter), and then the strictinin concentration was measured by HPLC in the same manner as in Test 3. The results are shown in Table 9 below.
[0081]
Also, 20 g of each of the above-mentioned tea leaves (Shizuoka crude tea) was added to 70 ° C. and 800 ml of ion-exchanged water (pH 5.9), respectively, and then extracted for 3.5 minutes while stirring every minute. The obtained extract was filtered through a mesh (150 mesh), rapidly cooled to room temperature, and then filtered (50 μm). 0.4 g of ascorbic acid is added to this extract, this is centrifuged at 7000 rpm for 10 minutes, the supernatant is finely filtered (1 μm MF membrane manufactured by Advantech), ascorbic acid is added, and ascorbic acid is added with ion-exchanged water and sodium bicarbonate. The acid was adjusted to 500 ppm, pH 6.0, Brix 0.1 (0.03 tea solid equivalent 0.03) to 0.3 (tea solid equivalent 0.23), and the strictinin concentration in this preparation was HPLC as in Test 3. Measured with
And further, after heating the said preparation liquid to 97 degreeC and filling in a heat-resistant wide-mouth bottle for orientation observation, it cools rapidly, performs retort sterilization on the conditions of 121 degreeC and 7 minutes, and stores at 37 degreeC after cooling. Changes were observed. The results are shown in the following Tables 9 to 11, FIG. 4 and FIG.
[0082]
In addition, the strictinin solid content ratio in the tea solid content in Table 9 is a value indicating the content ratio (%) of strictinin relative to the total tea solid content in the preparation liquid.
Table 10 is a table in which the data in Table 9 is rearranged in descending order of strictinin concentration in tea leaves by hot water extraction, and Table 11 is a table in which the data in Table 9 is rearranged in descending order of strictinin concentration in tea leaves by acidic extraction. It is.
FIG. 4 is composed of the strictinin concentration (ppm) in the prepared liquid when prepared on the horizontal axis: concentration of strictinine in tea leaves by hot water extraction (weight%), and the vertical axis: Brix 0.3 (converted to tea solid amount 0.23). It is the graph which plotted the presence or absence of secondary orientation generation | occurrence | production on the coordinate.
FIG. 5 shows coordinates composed of strictinin concentration (ppm) in the prepared liquid when the horizontal axis represents the concentration of strictinine in tea leaves (% by weight) by acidic extraction, and the vertical axis represents Brix 0.3 (tea solid amount conversion 0.23). It is the figure which plotted the presence or absence of secondary orientation generation | occurrence | production on the top.
[0083]
[Table 9]

[0084]
[Table 10]

[0085]
[Table 11]

[0086]
In the hot water extraction method adopted in the official method of tea tannin determination, the amount of strictinin extracted was small, but the acid hot water extraction method could effectively increase the amount of strictinin extracted. Moreover, as apparent from FIG. 4 and FIG. 5, it has been found that the acidic hot water extraction method has a much greater correlation with the secondary orientation. From this point of view, it is considered preferable to employ an acidic hot water extraction method, preferably an acidic hot water extraction method at pH 2 to 4 and 70 to 100 ° C., for measurement of the strictinin-containing concentration in the raw tea leaves. be able to.
[0087]
When Table 10 and FIG. 4 are seen, if the strictinine content concentration in tea measured by the hot water extraction method is 0.14% or less, the secondary orientation is hardly generated, and the strictinin content concentration in tea is 0.10%. It turned out that secondary orientation does not occur at all.
From Table 11 and FIG. 5, when the strictinine concentration in tea measured by the acidic extraction method is 0.43% or less, almost no secondary orientation is generated, and when the strictinine concentration in tea is 0.37% or less. It was found that there was no secondary orientation.
[0088]
From Table 11, it was found that the secondary orientation does not occur if the strictinin content in the preparation liquid is 6 ppm or less, more surely 5 ppm or less.
Considering from the viewpoint of the content ratio of strictinin to the tea solid content, in the case of a green tea beverage, the concentration of the preparation liquid (Brix) is about 0.2 (0.13 in terms of tea solids) to 0.3 (0.23 in terms of tea solids) ) Is general, so that the strictinin content relative to the tea solids in the tea extract or tea preparation is about 0.2 to 0.5%, particularly about 0.2 to 0.4% or less. If managed, the occurrence of secondary orientation can be eliminated. Specifically, it is preferable to adjust the upper limit value of the strictinin content relative to the tea solid content as an index by the tea solid content concentration (Brix) of the preparation liquid, and the tea solid content equivalent concentration (Brix of the tea extract or tea preparation liquid) ) Is 0.27% for 0.23, 0.34% for 0.18, and 0.48% for 0.13 as the upper limit of the strictinin content ratio with respect to tea solids. Is preferred.
[0089]
Test 12 (correlation 2 between strictinine concentration in tea and orientation 2)
For each of the 13 types of Chinese roasted tea (jasmine tea), the strictinin-containing concentration was measured by HPLC in the same manner as in Test 3, and the strictinin concentration at each stage for each tea leaf is shown in Table 12 below together with the observation results.
[0090]
In addition, 40 g of each of the 13 types of tea leaves (Chinese kettle roasted tea leaves (jasmine tea)) were added to 80 ° C. and 1000 ml of ion-exchanged water (pH 5.9), respectively, and stirred while stirring every minute. Extraction was performed for 3.5 minutes, and the obtained extract was roughly filtered with a mesh (150 mesh), rapidly cooled to room temperature, and then subjected to Nell filtration (50 μm).
This was centrifuged at 7000 rpm for 10 minutes, the supernatant was finely filtered (1 μm MF membrane manufactured by Advantech), ascorbic acid was added and ascorbic acid 500 ppm, pH 6.0, Brix 0.1 (brown 0.1) with ion-exchanged water and sodium bicarbonate. It was adjusted to 0.03) to 0.3 (0.23) in terms of tea solid amount, and the strictinin concentration in this preparation was measured by HPLC in the same manner as in Test 3.
Furthermore, after heating the preparation to 97 ° C and filling it into a heat-resistant wide-mouth bottle for orientation observation, it is rapidly cooled, sterilized at 121 ° C for 7 minutes, stored at 37 ° C after cooling, and changes over time. Was observed. The results are shown in the following Tables 12 to 14, FIG. 6 and FIG.
[0091]
In addition, the strictinin solid content ratio in the tea solid content in Table 12 is a value indicating the content ratio (%) of strictinin relative to the total tea solid content in the preparation liquid.
Table 13 is a table in which the data in Table 12 is rearranged in descending order of strictinine concentration in tea leaves by hot water extraction, and Table 14 is a table in which the data in Table 12 is rearranged in descending order of strictinin concentration in tea leaves by acidic extraction. It is.
FIG. 6 is composed of the strictinin concentration (ppm) in the prepared liquid when the horizontal axis is the strictinine concentration in tea leaves by hot water extraction (% by weight), and the vertical axis is Brix 0.3 (tea solid amount conversion 0.23). It is the graph which plotted the presence or absence of occurrence of orientation on coordinates.
FIG. 7 shows coordinates composed of strictinine concentration (ppm) in the prepared liquid when the horizontal axis represents the concentration of strictinine in tea leaves (% by weight) by acidic extraction, and the vertical axis represents Brix 0.3 (tea solid amount conversion 0.23). It is the figure which plotted the presence or absence of the occurrence of orientation.
[0092]
[Table 12]

[0093]
[Table 13]

[0094]
[Table 14]

[0095]
As a result, even in the case of jasmine tea, the extraction amount of strictinin was small in the hot water extraction method adopted in the official method for the determination of tannin in tea, but the extraction amount of strictinin was effectively improved by the acidic hot water extraction method. It was possible to increase. In addition, it has been found that the acidic hot water extraction method has a much greater correlation with the occurrence of secondary orientation. From this point, even in the case of jasmine tea, the measurement of the strictinin-containing concentration in the raw tea leaves is an acidic hot water extraction method, for example, pH about 4.5 or less, about 60-100 ° C., about 5-60 minutes, It can be considered that it is preferable to employ an acidic hot water extraction method in which extraction is preferably performed with acidic hot water at pH 2.0 to 4.0 and 70 to 100 ° C. for 10 to 30 minutes.
[0096]
Referring to Table 13 and FIG. 6, when the strictinine content concentration in tea measured by the hot water extraction method is 0.49% or less, almost no secondary orientation is generated, and the strictinine content concentration in tea is 0.33%. It turned out that secondary orientation does not occur at all.
From Table 14 and FIG. 7, when the strictinine concentration in tea measured by the acidic extraction method is 0.90% or less, almost no secondary orientation is generated, and when the strictinine concentration in tea is 0.61% or less. It was found that there was no secondary orientation.
[0097]
From Table 14, it was found that the secondary orientation does not occur if the strictinin content in the preparation liquid is 14 ppm or less, more reliably 13 ppm or less.
Considering from the viewpoint of the content ratio of strictinin to the tea solid content, in the case of a jasmine tea beverage, the concentration of the liquid mixture (Brix) is about 0.2 (0.13 in terms of tea solids) to 0.3 (in terms of tea solids 0. 23) is common, so that the strictinin content relative to the tea solids in the tea extract or tea preparation is about 0.5 to 1.1%, particularly about 0.6 to 0.8% or less. If this is managed, the occurrence of secondary orientation can be eliminated. Specifically, it is preferable to adjust the upper limit value of the strictinin content for the tea solid content as an index by the tea solid content concentration (Brix) of the preparation liquid. When the tea solid content conversion concentration (Brix) of the tea extract or tea blend solution is 0.23, it is 0.62%, 0.18 is 0.80%, 0.13 is 1. It is preferable to set 11% as the upper limit of the strictinin content ratio with respect to the tea solid content.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a work procedure of test 2 (ori component analysis test).
FIG. 2 shows that in test 4 (thermal decomposition test of strictinin), the purified strictinin solution was subjected to retort sterilization, and the strictinin content and ellagic acid content of “prepared solution before heat sterilization” and “prepared solution after heat sterilization” were measured by HPLC. It is a graph which shows the result measured by.
[Fig. 3] In test 4 (thermal decomposition test of strictinin), the prepared solution obtained by adding purified strictinin to the “HP-20 non-adsorbed fraction” obtained in test 1 was subjected to retort sterilization, and “prepared solution before heat sterilization” It is a graph which shows the result of having measured the strictinin content and ellagic acid content of "preparation liquid after heat sterilization" by HPLC.
FIG. 4 shows that in test 11 (correlation 1 between the concentration of strictinin in tea leaves and orientation), the horizontal axis: the concentration of strictinine in tea leaves by hot water extraction (% by weight), the vertical axis: Brix 0.3 (0. It is the graph which plotted the presence or absence of generation | occurrence | production of origin on the coordinate which consists of strictinin concentration (ppm) in the liquid preparation at the time of preparing to 23).
FIG. 5: In Test 11, the strictinin concentration (ppm) in the prepared liquid when the horizontal axis is the strictinine concentration in tea leaves (% by weight) by acidic extraction, and the vertical axis is Brix 0.3 (tea solid amount conversion 0.23). ) Is a graph in which the presence or absence of orientation is plotted on the coordinates.
FIG. 6: In Test 12 (correlation 2 between strictinin concentration in tea leaves and ori formation 2), the horizontal axis: strictinin concentration in tea leaves by hot water extraction (wt%), the vertical axis: Brix 0.3 (tea solids conversion 0. It is the graph which plotted the presence or absence of generation | occurrence | production of origin on the coordinate which consists of strictinin concentration (ppm) in the liquid preparation at the time of preparing to 23).
FIG. 7: In test 12, the horizontal axis: strictinine concentration in tea leaves by acid extraction (% by weight), the vertical axis: Brix 0.3 (0.23 in terms of tea solid amount), the strictinin concentration in the preparation (ppm) ) Is a graph in which the presence or absence of orientation is plotted on the coordinates.

Claims (3)

Tea leaves are extracted with hot water, and the strictinin-containing concentration in the extract is measured, and the strictinin-containing concentration is 0.49% or less for weakly fermented tea and 0.14% or less for non-fermented tea. Or select
Tea leaves are extracted with acidic hot water, and the strictinin-containing concentration in the extract is measured, and the strictinin-containing concentration is 0.90% or less for weakly fermented tea and 0.43% or less for non-fermented tea A method for selecting raw materials for container-packed tea beverages, characterized by selecting tea .   The tea-packed tea drink according to claim 1, wherein the concentration of strictinin in the extract obtained by extracting tea leaves with hot water at 60 to 100 ° C for 5 to 60 minutes and filtering after cooling is measured. To select raw materials.   The strictinin-containing concentration in the extract obtained by extracting tea leaves with hot water at pH 4.5 or less and 60-100 ° C for 5-60 minutes, and filtering after cooling is measured. To select ingredients for container-packed tea beverages.

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