JP4608051B2

JP4608051B2 - Modified starch and method for producing the same

Info

Publication number: JP4608051B2
Application number: JP2000096791A
Authority: JP
Inventors: 丕藤野; 純佚吉田; 昌彦芳村; 善市吉野; 利章小巻; 昌裕倉掛; 直良井ノ内
Original assignee: 三和興産株式会社
Priority date: 2000-03-31
Filing date: 2000-03-31
Publication date: 2011-01-05
Anticipated expiration: 2020-03-31
Also published as: JP2001275585A

Description

【０００１】
【発明の属する技術分野】
本発明は各種澱粉を原料として変性された食品用途、工業用途に用いる変性澱粉及びその製造方法に関し、さらに詳しくは糊化温度が低く、容易に加熱によって溶解しその溶液の粘度が低いこと、さらに冷却しても実質的に粘度が増加しないことを特徴とした、溶解度が高く、沃素呈色度が低く、しかも殆ど非還元性で、低分子を主体とする、食品用途、工業用途において優れた性質を有する変性澱粉及びその製造方法である。
【０００２】
【従来の技術】
加工澱粉の中で最も古くより知られているのは焙焼デキストリンで、白色デキストリン、黄色デキストリン、さらにブリティッシュガムと呼ばれてきた製品がある。何れも粉体の澱粉を薬液浸漬、予備乾燥、焙焼、冷却、調湿する工程を経たのち製品とされるが、１１０〜２２０℃の焙焼温度で加熱して作られる。通常白色デキストリンは１２０℃前後に、黄色デキストリンは１５０〜２００℃に、ブリティッシュガムは２２０℃に加熱されることが知られている。薬液浸漬としては、塩酸、硝酸、アンモニア、炭酸ナトリウム等の溶液に含浸させ、予備乾燥で水分１０％程度まで乾燥するのが一般的である。
【０００３】
一般的に澱粉およびその加工品の利用はその高分子的性質が利用され、高粘度であることが特徴とも言える。これら従来の焙焼デキストリンの主たる目的は接着剤等の工業的用途で、この場合、溶解性が澱粉より優れかつ比較的高粘度の製品が多い。低粘度の製品としては次亜塩素酸ナトリウムで酸化した加工澱粉があるが、溶液化後温度が下がると粘度が増加する。
【０００４】
【発明が解決しようとする課題】
本発明は、かかる用途をより多方面に広げるために澱粉の高分子的性質を改善し、新しい用途に適した製品を提供するために創案されたものであり、その目的は澱粉を塩類溶液と共に加熱処理するだけの簡単な操作で製造できるデキストリンの製造法を改良することにより、低粘性の、非還元性でメーラード反応を起こし難く、食品分野にも広く活用できる変性澱粉及びその製造方法を開発することにある。特に、近年その需要が増加しつつある調味料、スープなどの粉末化基剤としての用途では、各種の動植物の抽出により得られた高濃度のエキスの粉末化にはできるだけ高い濃度に溶解し、低粘度で、他成分との反応性が少なく、かつ噴霧乾燥後吸湿性の少ない粉末基剤が望まれているが、本発明はかかる用途に好適な変性澱粉を提供しようとするものである。
【０００５】
また、本発明は、各種の食品の艶出し剤や冷凍食品の冷凍時に表面の水分の蒸散を防ぐ目的で被膜を作らせたり、さらには乾燥魚類の乾燥の際に浸漬することで表面に被膜を形成して乾燥貯蔵中の酸化を防止するために、適当な濃度に溶解し浸漬したり、噴霧して表面に付着させるなどに用いることができる変性澱粉を提供しようとするものである。揚げ物の打ち粉や小麦粉を主成分とするフライ物の衣に混合する素材として、また工業的には石膏ボードの強度を増強したり、製紙用表面塗工剤などの目的に澱粉を用いるには、低粘度であることが他成分と均一に分散混合するために必要不可欠の要素である。しかもある程度の高分子であることが要求される。これらの目的には酸化澱粉が利用されることが多いが、本発明の方法による変性澱粉はこれらの広い範囲に利用できることを目的にした。本発明では、低粘度としての基準は変性された澱粉の粘度が元の澱粉の１／１０以下であって、固形物濃度３０％という高濃度で粘度測定が可能で、糊化温度が低く、糊液が低粘度を示すこと、さらに温度が低下しても粘度上昇が少ないこと、すなわちセットバックが少ないことなどを目標にした。
【０００６】
【課題を解決するための手段】
本発明者は上記課題を達成するために鋭意検討した結果、各種澱粉に適量の塩類を溶解した水を添加混合した湿混合物を、１３０℃前後の高温度で数時間加熱処理することによって、澱粉の物性が著しく変化し、上記用途に適した新規な変性澱粉が製造できることを発見した。
【０００７】
上記変性澱粉の物性の変化としては、まず（１）糊化温度と粘性の著しい低下がある。糊化温度、粘性の測定はＲＶＡ（ラピッドヴィスコアナライザー）、アミログラム等で知られている定速昇温降温自動回転粘度計を用いて加熱過程及び冷却過程での粘度変化を測定し、糊化開始温度、最高粘度、最高粘度到達温度、最低粘度、最高粘度到達後高温度を保った後の最低粘度と元の最高粘度との差（ブレークダウン）、その後の冷却時の粘度上昇、冷却後の粘度と最低粘度との差（セットバック）等を測定した。本発明の変性澱粉は３０重量％の高濃度での粘度測定が可能なほど低粘度で、しかもセットバックがほとんどないことが特徴である。次に（２）沃素による呈色性（比青価）の低下、更に（３）還元力の増加がほとんどない、（４）４０℃での水に対する溶解性の増加、（５）４０℃での膨潤性の増加、（６）糊化度（α−化度）の変化、（７）糊液のゾル化、ゲル化特性の変化等が観察された。
【０００８】
次に分子構造の変化については、（８）アミラーゼによる消化性の減少、（９）アルカリ溶液のゲル濾過剤を用いたカラム分画による鎖長分布の測定により認められる重合度数万以上の高分子アミロペクチン及び重合度数千の高分子アミロース区分の減少と、重合度１０００以下の低分子の増加、（１０）イソアミラーゼによる消化液の中圧カラム分画による分岐分子の側鎖の鎖長を測定した結果から重合度１００以上と推定される沃素呈色の最高波長６２０ｎｍの長波長のアミロース区分（ＦｒＩ）の減少と、長鎖区分ＦｒII（長いＢ鎖）、短鎖区分ＦｒIII（Ａ鎖と短いＢ鎖）のほぼ同量の増加が観察された。このように今まで知られていない特性を持った変性澱粉が澱粉に特別な化学反応処理を施すことなく単に塩類を添加して加熱処理するだけで製造することが可能となった。
【０００９】
また、本発明者は、加熱処理時に共存させる塩類の種類、濃度、湿混合物のｐＨ、加熱処理温度、加熱処理時間のそれぞれが変性澱粉の特性に大きく影響し、これらを変化させることで上記した変性澱粉の物理的性質の変化が連続的に起こることを発見した。
具体的には、この場合の変性効果（即ち製品の粘性等の上記したような性質の変化）に大きく影響する因子として、（１）添加する塩の種類、（２）添加混合する塩類濃度、（３）加熱処理温度と時間、（４）加熱処理時の湿混合物のｐＨ、（５）澱粉の種類等であることを見いだした。これらの（１）〜（４）の処理条件と（５）澱粉の種類を組合せることで変性度の種々異なる変性澱粉の製造が可能である。最初コーンスターチを用いた実験で他の澱粉に比較して少量の塩化マグネシウムの添加が粘度低下に著しい効果を示したが、これはコーンスターチ自体のｐＨが４．３〜４．７と酸性領域にあることが原因であることを見いだした。添加する塩の種類によって、またその添加量によって、さらにｐＨによって、加熱温度と時間によって異なる結果が得られた。そしてこれらの因子間には相互作用が認められた。
【００１０】
粘性、糊化性の変化については、処理条件が進むに従い、糊化開始温度が低くなり、最高粘度が低くなり、最高粘度到達温度も低くなり、全く最高粘度を示さないように変化する。また加熱冷却後の粘度の増加、即ちセットバックが殆ど見られないように変化する。同時に４０℃での溶解度が高くなり、膨潤度も高くなり、沃素による呈色性（比青価）も低下して原澱粉の３０％以下になるが、一方で還元力の増加は極めて僅かであり、１％以下である。粘性、糊化性、溶解性、沃素呈色性、比青価等の特性の変化の間にも相互に関連があり、図１に示すように、馬鈴薯澱粉に塩類を様々な濃度で添加した変性澱粉について、未処理澱粉に比較した比青価（沃素呈色度）が３０％以下に低下すると最高（ピーク）粘度は急激に低下し、殆ど粘度が測定できなくなる。同時に４０℃での溶解度は比青価４５％以下に低下すると急激に増加する傾向を示す。比青価が大きく低下しているが、還元力の増加は極めて少なく実質的に加水分解が進んだとは解釈し難い。
【００１１】
さらに、分子量分布の変化についても次のようにして確認した。馬鈴薯澱粉に、０．０４２ｍｏｌ／ｋｇ澱粉（０．０５１ｍｏｌ／ｋｇ乾物澱粉相当）になるような塩化マグネシウム及び５．０ｍｍｏｌ／ｋｇ澱粉になるような塩酸を溶解した水溶液を混合し、この湿混合物の水分を２７重量％、ｐＨを４．５とした。次に、この湿混合物をアルミバット上に約１ｃｍの厚みに均一に広げて、１３５℃の乾熱殺菌機内で５時間加熱処理した試料について分子量分布の変化を測定した。
まず第１に、試料澱粉をアルカリ溶液として、多孔性のゲル濾過材であるトヨパールＨＷ７５Ｓを充填したカラムで分子量分布の分画をした。各分画の糖量を定量し、同時に沃素反応による５４０ｎｍ及び６６０ｎｍの吸光度を測定し、単に加水のみで加熱処理した対照サンプルと比較した。その結果から、高分子（重合度数万以上）のアミロペクチン及び高分子（重合度数千）のアミロース区分は殆ど消失して、重合度約千以下に低分子化された区分が増加し、さらにこの区分は５４０ｎｍの吸光度が６６０ｎｍよりも２倍程度高く、短鎖低分子が主体であることが明らかになった（図２）。この事実が、低粘性、低青価に変化した原因である。
【００１２】
さらにイソアミラーゼを用いて分岐点を枝切りして全分子を直鎖とした試料について、トヨパールＨＷ５５Ｓ−ＨＷ５０Ｓ中圧カラムクロマトグラフィーで分岐側鎖の鎖長分布を測定したところ、対照サンプルに見られる鎖長１００以上のアミロース区分のＦｒＩが殆ど消失し、次に鎖長７０〜１００のＩｎｔＦｒおよび３５〜７０の長鎖区分のＦｒII及び３５以下の短鎖区分のＦｒIIIがＦｒＩの消失分増加しており、長いＢ鎖と短いＢ鎖及びＡ鎖が増加し、その増加量がほぼ消失したアミロース区分と同量であることを示した（図３参照）。さらに試料澱粉分子の分岐点をイソアミラーゼで枝切りした試料について、ＤＩＯＮＥＸを用いたクロマトグラフィーでのイオン交換クロマト法と、溶出した糖質をパルスドアンペロメトリー検出器で直接検出する方法で、対照サンプルと比較したところ、重合度３〜５の低分子側鎖が、対照と比較して馬鈴薯澱粉ではｍｏｌ比で４４．４％、コーンスターチでは２２％と大きく増加生成しており、重合度が１１〜１７程度までの長鎖側鎖は逆に半分程度に減少していることが解明された。
これらの結果は、澱粉分子中で長鎖区分が切断されていると同時に、短鎖分岐分子が大きく増加したことを意味しており、沃素呈色度が低下しているにもかかわらず還元量が増加しないこと、また粘性、糊化性が大きく変化したこと、セットバックが少ないこと、４０℃での溶解度の増加等の変化を裏付けている。
【００１３】
また各種酵素による加水分解挙動では、β−アミラーゼによる分解限度が対照澱粉に比べて約１０％程度低い結果が得られた。また枝切り酵素であるプルラナーゼを共用しても分解率は５０％程度であった。グルコアミラーゼによる分解度も低い値が得られた。
【００１４】
以上の知見から本発明者等は全く新しい特性を持った変性澱粉とその製造方法を完成するに至った。
即ち、本発明によれば、澱粉、水分及び０．０１〜１．０ｍｏｌ／ｋｇ澱粉の割合の塩類を含む湿混合物を３〜６のｐＨ及び１１０〜１５０℃の温度で１〜８時間加熱処理する工程を含むこと、及び前記澱粉がコーンスターチ、馬鈴薯、甘藷、タピオカ、小麦、ハイアミロースコーンスターチ、又はワキシーコーンスターチであり、前記塩類がマグネシウム、亜鉛、マンガン又はカルシウムの２価金属塩、塩化ナトリウム又は塩化カリウムであることを特徴とする低粘性で還元力の実質的にない変性澱粉の製造方法が提供される。
また、本発明によれば、上記の製造方法によって得られる低粘性で還元力の実質的にない変性澱粉であって、３０重量％の濃度の溶液にしたときに粘度測定が可能であり、かつ加熱糊化後のセットバックがほとんどないことを特徴とする変性澱粉が提供される。
本発明の変性澱粉は、上述のような性質を有するため、食品用粉末化基材、食品用表面処理剤、揚げ物の打ち粉もしくはフライ物の衣に混合する素材、石膏ボードの補強材料、接着剤、または製紙用表面塗工剤として有用である。
【００１５】
【発明の実施の形態】
本発明の変性澱粉の製造工程の実際の操作は本質的には次の２工程から成り立つ。即ち、澱粉、塩類、及び水分を均一に混合する第１工程と、次に、かかる湿混合物を加熱処理により着色しない程度の温度として１１０〜１５０℃の範囲内で１〜８時間加熱処理する第２工程からなる。
【００１６】
以下に本発明の各製造工程について説明する。
本発明では塩類の添加濃度の表示は、ｍｏｌ／ｋｇ澱粉と表示したが、これは澱粉量１ｋｇに対して添加する塩の分子量に等しいグラム数を意味する。ここで言う澱粉は平衡水分を含んだ状態の市販澱粉のことを意味しており、例えば馬鈴薯澱粉と言えば約１８重量％の水分を含むものである。０．５ｍｏｌ食塩／ｋｇ澱粉は食塩の分子量が５８．５であるから２９．２５ｇ食塩／ｋｇ澱粉となる。塩化マグネシウム・６水和物では、分子量は２０３．３であるから、澱粉１ｋｇ当たり２０．３３ｇが０．１ｍｏｌ／ｋｇ澱粉となり、澱粉に対して２．０３３％ｗ／ｗとなる。もし無水の塩化マグネシウムを用いるならば分子量は９５．３であるから、０．９５３％ｗ／ｗが０．１ｍｏｌ／ｋｇ澱粉となる。
【００１７】
まず本発明で使用する塩類としては、食品製造において通常用いられる塩化ナトリウム（食塩）や塩化カリウムのような１価塩類の他に、マグネシウム、亜鉛、マンガン、カルシウム等の２価の無機塩類が挙げられる。２価の無機塩類の中では、粘度低下等の変性効果は、マグネシウム＞亜鉛＞マンガン＞カルシウムの順に大きく、マグネシウム塩が最も少ない量で効果が大である。塩類の必要使用量は、加熱温度、澱粉の種類、処理時のｐＨ等によって随分影響され、目的によってどの程度まで変性させるかによっても異なる。一般的には本発明の変性澱粉の製造には０．０１〜１．０ｍｏｌ／ｋｇ澱粉の割合の塩類を使用する。例えば湿混合物のｐＨが４．５、加熱処理温度が１３５℃であるなら、上記の２価金属塩の場合は０．００５ｍｏｌ／ｋｇ澱粉から有効であり、例えば塩化マグネシウムの場合は０．０１〜０．０５ｍｏｌ／ｋｇ澱粉が好ましい。塩化ナトリウム、塩化カリウム等の１価の塩類の場合は２価金属塩に比較して変性効果が少ないので、０．０５〜１．０ｍｏｌ／ｋｇ澱粉、好ましくは０．１〜０．５ｍｏｌ／ｋｇ澱粉の使用量が好ましい。
【００１８】
本発明で使用する澱粉としては、従来公知のいずれのものであってもよいが、例えば工業的に使用が可能なコーンスターチ、馬鈴薯、甘藷、タピオカ、小麦、ワキシーコーンスターチ、ハイアミロースコーンスターチなどが挙げられる。澱粉の種類によって本発明の加熱処理による粘性の低下にかなりの差が認められ、上記澱粉の中ではワキシーコーンスターチ、コーンスターチが最も粘性の低下が大きかった。これは製造法に起因してコーンスターチ自体のｐＨが低いためであり、処理時のｐＨが大きく影響することを発見した。この低ｐＨのコーンスターチ自体を塩類の添加なしで１３０℃で加熱しても最高粘度は僅かに低下する程度で、含有する酸のみでは加熱処理による変性効果は殆どないことを確認した。
【００１９】
湿混合物の加熱処理時の加熱温度については湿混合物が着色しない程度の温度を選定すべきである。塩類の添加濃度と温度との間に相関関係が見出され、高塩濃度では低温が低塩濃度では高温が要求される。従って高塩濃度、高温度ほど着色し易い傾向にある。澱粉の加熱着色を避けることを考慮すると加熱温度は１１０〜１５０℃の温度が実用的であり、１３５℃を標準とした。バッチ式の場合は湿混合物を薄く広げて加熱しないと均一加熱処理が難しいので大量生産の場合はジャケット及び撹拌翼等に加熱装置が付いたもの、あるいは加熱用パイプを付設された混合・加熱型の装置を用いることが好ましい。加熱時間は加熱方式によって異なるが、１〜８時間が実用的であり、約５時間を標準とした。
【００２０】
澱粉の種類の差については、未処理の生馬鈴薯澱粉では１０重量％濃度での粘度測定結果は糊化開始温度６０．８℃、最高粘度到達温度７１．７℃、最高粘度７９４ＳＮＵ（Stirring Number of Unit）、最低粘度１９０ＳＮＵ、ブレークダウン６０４ＳＮＵ、冷却時粘度２４７ＳＮＵ、セットバック５７ＳＮＵであった。同じく未処理のコーンスターチではそれぞれ７２．４℃、８９．９５℃、３００ＳＮＵ、１０６ＳＮＵ、１９４ＳＮＵ、１０６ＳＮＵ、１４８ＳＮＵであった。本発明では低粘度とは３０重量％濃度で粘度測定が可能であって、最高粘度が５００ＳＮＵ以下、またセットバックの実質的にないものを言う。
【００２１】
コーンスターチを例にとると塩化マグネシウムを用いた場合、０．００８ｍｏｌ／ｋｇ澱粉と僅かの使用で、１３５℃で５時間加熱処理すると３０重量％濃度で粘度が測定可能で、セットバックが少なく冷却しても粘度が殆ど上昇しない点まで変性するが、１３０℃では粘度は低下するが、加熱による粘度上昇及びセットバックが大きい。１３０℃、５時間加熱の条件でも塩化マグネシウムの量を０．０１３ｍｏｌ／ｋｇ澱粉以上とすると、変性が進んで粘度が測定不能な低粘度になる。１３５℃、５時間加熱処理では、０．０１ｍｏｌ／ｋｇ澱粉以上で同様になる。また４０℃での溶解度が大きくなり、沃素呈色の比青価も未処理生澱粉の３０％以下になる。しかし還元力の増加は２％以下で、加水分解はあまり進んでいないと考えられる。
【００２２】
コーンスターチのｐＨはその製造工程から持ち込まれる酸の存在で通常４．５付近である。この低ｐＨが原因している可能性について検討するため、市販コーンスターチを多量の希アルカリ溶液で洗浄したｐＨ８．３のコーンスターチを使用した場合、塩化マグネシウム０．０２ｍｏｌ／ｋｇ澱粉の使用でも、１０重量％濃度で比較して未処理のコーンスターチより僅かに低粘度化した程度で、加熱処理時のｐＨが微アルカリ状態では効果がないことが明らかになった。これはマグネシウムの溶解も影響していると考えられる。この洗浄微アルカリコーンスターチに塩酸と共に塩化マグネシウム０．０２ｍｏｌ／ｋｇ澱粉を添加してｐＨを４．９とした場合は３０重量％濃度での粘度測定が可能な程度に粘度が低く、最高粘度も８０ＳＮＵと低く、冷却しても粘度上昇は殆ど認められなかった。
【００２３】
次に馬鈴薯澱粉を原料とする場合は、特徴として糊化温度が低く最高粘度が高くブレークダウンが大きく、それ自体のｐＨが中性に近いこともあって、塩化マグネシウムの添加量を多くしないと変性効果は出なかった。１３５℃、５時間加熱では塩化マグネシウムの添加量を０．０４２ｍｏｌ／ｋｇ澱粉とすると、３０重量％濃度で最高粘度が測定可能な低粘度になる。ブレークダウンが大きく、加熱後は殆ど粘度が測定不可能なくらい低粘度になり、冷却後も粘度の上昇がなくセットバックが認められない。また糊液は透明で、室温及び４０℃で放置して１週間経過しても透明状態を保つこと、また粘度の上昇もほとんどないこと、すなわち老化に対して安定であることが認められた。この場合塩化マグネシウム添加時に同時に塩酸を０．００３〜０．００７５ｍｏｌ／ｋｇ澱粉加え、湿混合物澱粉のｐＨを４〜５．３に低下させると粘度低下効果は著しく大になる。このことは甘藷（一例ｐＨ５．６）、タピオカ澱粉（一例ｐＨ６．８）の場合も同様の傾向を示す。
【００２４】
従って、馬鈴薯、甘藷、タピオカその他のｐＨが中性に近い澱粉の場合は、酸を共存させて湿混合物のｐＨを５．３以下の酸性とすることで塩類添加量を低減することが可能であり、変性の目的に対応してより低粘性のもの又は冷却時の粘度上昇の少ないものを希望するときは、当該変性澱粉の使用目的から許せる範囲でｐＨを下げれば、それだけ変性効果が大となり塩類の添加量を削減することができる。このことは変性澱粉製品の味覚にも大きく影響する。用いる酸の種類は特に限定されないが、変性澱粉の使用目的に対して適当な酸を選択して使用する。食用の場合はクエン酸が適している。
【００２５】
甘藷の場合は、ｐＨが約５．６〜５．８で塩化マグネシウムが０．０４２ｍｏｌ／ｋｇ澱粉で、１３５℃、５時間の加熱処理でも、３０重量％濃度で最高粘度が現れ、またセットバックも最高粘度まで達するが、塩酸を０．００３ｍｏｌ／ｋｇ澱粉添加してｐＨを４．８として同様に加熱処理すれば、処理澱粉は加熱しても、また加熱後冷却しても殆ど粘度増加が認めらず、即ちセットバックが小さい変性澱粉になる。
【００２６】
タピオカ澱粉の場合は、ｐＨ６．８で１３５℃、５時間加熱処理の条件で０．０４２ｍｏｌ／ｋｇ澱粉で最高粘度はかなり低下するが、冷却に伴って粘度増加が著しい、即ちセットバックが大きい。しかしこの場合も塩酸を０．００３ｍｏｌ／ｋｇ澱粉添加してｐＨを４．５程度に下げるとセットバックが小さい澱粉に変性された。
【００２７】
第１工程の塩類（及び酸）と澱粉との混合は、例えば適当量の水に塩類を溶解し、必要なときは予め酸液を加えてｐＨを調整し、これに塩類を溶解し澱粉と混合して行われる。また水分は両者が均一に混合できるのに必要な最少量で良い。上記混合に使用する混合機は従来公知の各種のものが利用でき、特別な仕様は要求しない。
【００２８】
第２工程の加熱処理であるが、当然ながら湿混合物が均一に加熱処理されることが必要である。加熱時間も加熱処理中に撹拌混合するか、または静置で行うかは熱源の種類等の加熱処理条件で異なるが、常に一定の品質の変性澱粉を得たい場合は装置ごとに加熱方法を検討しなければならない。必要な加熱時間は伝熱の効率で異なるが、水分が少ないため伝熱効率は良くないので静置加熱の場合少なくとも４〜５時間は必要である。例えば馬鈴薯澱粉で塩化マグネシウム０．０４２ｍｏｌ／ｋｇ澱粉を混合し、１３５℃で静置加熱した場合、３時間では３０重量％濃度では粘度が高くて測定できないが、４時間加熱すると糊化開始温度も低下し粘度測定が可能な程度まで変性する。撹拌混合型の効率の良い装置の場合は比較的短時間の加熱で十分である。
【００２９】
本発明の変性澱粉を以下の実施例によって示すが、本発明はこれらに限定されるものではない。
【００３０】
【実施例】
実施例１
混合機として備文機械製の直径３６ｃｍ、最深部１８ｃｍの石臼型、３本撹拌棒型の擂潰機を用いた。市販コーンスターチ（水分１３％、ｐＨ４．７）５００ｇに、水１１０ｍｌに塩化マグネシウム・６水塩を０．００８〜０．０６６ｍｏｌ／ｋｇ澱粉溶解した溶液を混合しながら添加して約２０分間混合し湿混合物を得た。水分計算値は２８．６８重量％であったが、混合した後は２６〜２７重量％であった。
【００３１】
この湿混合物を２６×１９×５ｃｍのステンレス製バットにアルミホイルで３区分に分割し、１区画に１１０ｇの湿混合物を約１ｃｍの厚みに広げ、それぞれを１２５℃、１３０℃及び１３５℃に調整した送風式恒温器中で５時間加熱処理した。塩化マグネシウムが高濃度で、しかも高温度になると、やや着色が認められたが、顕微鏡的外観には殆ど変化がなかった。各種測定結果を表１及び表２に示した。粘度測定は３０％濃度で行った結果である。これらの表より明らかな如く１３５℃加熱処理では０．０８ｍｏｌ／ｋｇと低濃度でも著しい粘度低下効果が認められ、０．０１３ｍｏｌ／ｋｇ澱粉では４０℃での溶解度が７７％まで増加し、昇温を続けても粘度の上昇は認められず、９５℃、５分加熱後冷却しても粘度は全く上昇しなかった。１２５℃では０．０４２ｍｏｌ／ｋｇ澱粉以上の高濃度で同様の結果が得られ、塩化マグネシウムの添加濃度と加熱温度の組み合わせで、粘性を始めとして沃素呈色の比青価、４０℃での溶解度等種々の物性をかなり広範囲に変化させる可能性が明らかになった。その結果を下記表に示す。
なお、β−アミラーゼによる消化率について、塩化マグネシウム０．０４２ｍｏｌ／ｋｇ澱粉添加で１３０℃加熱した変性澱粉と塩無添加で単に同一条件で加熱処理のみした澱粉とを比較したところ、塩添加澱粉の方が約１１％程度低い値を示した。
【００３２】
【表１】

【００３３】
【表２】

【００３４】
実施例２
実施例１と同様の混合機として備文機械製の直径３６ｃｍ、最深部１８ｃｍの石臼型、３本撹拌棒型の擂潰機を用いた。市販北海道産馬鈴薯澱粉（水分１８％、ｐＨ６．７）５００ｇに、水７０ｍｌに塩化マグネシウム・６水塩、塩化亜鉛、塩化マンガン、塩化カルシウムの所要量をそれぞれ溶解して、撹拌しながら添加した。水分計算値で２８．７重量％であったが、２０分間撹拌・混合を続けた後は少量蒸発して２６〜２７重量％になった。
【００３５】
それぞれの湿混合物を送風式恒温器中で、２６×１９×５ｃｍのステンレス製バットを三区画とし、これへ湿混合物１１０ｇを約１ｃｍの厚みに薄く広げて１３５℃で５時間加熱処理した。この加熱処理澱粉について種々の性質を比較した。粘度特性を下記表に示す。
【００３６】
【表３】

【００３７】
【表４】

【００３８】
これらの表の結果から塩類添加濃度はコーンスターチに比較して高濃度を必要とすること、また塩類の種類によって著しい差があることが明らかになった。
塩化マグネシウムでは０．０４２ｍｏｌ／ｋｇ澱粉で、また塩化亜鉛では０．０６２ｍｏｌ／ｋｇ澱粉で、３０重量％濃度での粘度測定値が５００ＳＮＵ以下となったが、塩化カルシウムでは０．０６２ｍｏｌ／ｋｇ澱粉でも十分な粘度低下は認められなかった。しかし１０重量％濃度で測定すると、未処理のものと比較して著しい粘度低下が認められ、０．０４２ｍｏｌ／ｋｇ澱粉で最高粘度は５０ＳＮＵ以下になり、さらに加熱することで粘度は低下した。なおその後の粘度上昇は殆ど生じないこと（即ち、セットバックがないこと）を確認した。
【００３９】
実施例３
実施例２と同様の操作で馬鈴薯澱粉に、水に塩類を所要量溶解したものを添加し、さらに塩酸を添加してｐＨを低下させた湿混合物を１３５℃、５時間加熱処理した場合の結果を下記表に示した。
【００４０】
【表５】

【００４１】
【表６】

【００４２】
これらの表の結果から塩酸を０．００３，０．００５，０．００７５ｍｏｌ／ｋｇ澱粉添加して塩混合湿澱粉のｐＨをそれぞれ５．１，４．６，４．０とすることで、粘度低下効果その他変性効果が明らかに大になり、実施例２で２価塩類中最も効果の低かった塩化カルシウムも０．０４２ｍｏｌ／ｋｇ澱粉で実用的な変性効果があり、粘度低下、沃素呈色による比青価、４０℃溶解度等が著しく変化することを見いだした。
【００４３】
実施例４
実施例２と同様の操作を甘藷澱粉について行った。市販甘藷澱粉（水分１４．６％、ｐＨ５．６）５００ｇと水９９ｍｌ中に塩化マグネシウム０．０４２ｍｏｌ／ｋｇ澱粉を添加し、この中に塩酸０．００３ｍｏｌ／ｋｇ澱粉添加し、ｐＨ４．８とした湿混合物（水分計算値２８．７％、実測値２７．９％）を１３５℃、５時間加熱処理した。その結果を下記表に示した。
【００４４】
【表７】

【００４５】
この表の結果から馬鈴薯澱粉と同様に塩酸を添加してｐＨを４．８に低下した方が塩化マグネシウムの添加効果が大になり、糊化温度が約１５℃低く、最高粘度も低く、かつセットバックが殆どなく、沃素反応の比青価が３７％程度に減少したが、溶解度は馬鈴薯澱粉ほど増加しない澱粉となった。ｐＨ５．６の状態で塩化マグネシウムを添加した場合は、最高粘度は低下し、加熱を続けるとブレークダウンもかなり大きかったが、冷却に伴う粘度上昇、即ちセットバックが大きいのが特徴であった。
【００４６】
実施例５
実施例２と同様の操作をタピオカ澱粉について行った。タピオカ澱粉（水分１２．３％、ｐＨ６．８）５００ｇと水１１５ｍｌに塩化マグネシウム０．０４２ｍｏｌ／ｋｇ澱粉を溶解し、これに塩酸０．００３ｍｏｌ／ｋｇ澱粉を添加してｐＨを４．５とした湿混合物（水分計算値２８．７％、実測値２８．３％）を１３５℃、５時間加熱処理した。その結果を下記表に示した。
【００４７】
【表８】

【００４８】
タピオカ澱粉の特徴として、塩化マグネシウム０．０４２ｍｏｌ／ｋｇ澱粉のみの添加では、最高粘度はかなり低下し１５％程度になるが、セットバックが大きく、加熱後低下した粘度が冷却することで粘度が著しく上昇し最高粘度より大になった。しかし酸を加えて酸性で加熱処理することで糊化温度も低く、最高粘度もまた冷却後の粘度も殆どない澱粉に変性された。
【００４９】
実施例６
実施例２と同様の操作で、馬鈴薯澱粉２５０ｇに、食塩０．７３０５ｇ（０．０５ｍｏｌ／ｋｇ澱粉）および７．３０５ｇ（０．５ｍｏｌ／ｋｇ澱粉）、水２２．５ｍｌ、１ｍｍｏｌ塩酸２５ｍｌを溶解して混合し、この湿混合物を１３５℃、５時間加熱処理した。このもののｐＨは４．１であった。その結果を下記表に示した。
【００５０】
【表９】

【００５１】
この表の結果から、塩類として食塩を添加する場合、塩化マグネシウムに比べてかなりの量を添加しなければ変性効果が発現できないと考えられる。
【図面の簡単な説明】
【図１】変性処理馬鈴薯澱粉のＲＶＡによる最高粘度及び４０℃溶解度と比青価との関係を示す。
【図２】塩化マグネシウム変性処理馬鈴薯澱粉のゲル濾過カラム分析による分子量分布を示す。
【図３】塩化マグネシウム変性処理馬鈴薯澱粉の枝切り酵素により切断した分子の中圧カラムによるクロマトグラフィーを示す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to modified starch used for food applications and industrial applications modified from various starches as a raw material, and a method for producing the same, and more specifically, the gelatinization temperature is low, the gel is easily dissolved by heating, and the viscosity of the solution is low. It is characterized by high viscosity, low iodine coloration, almost non-reducing, mainly composed of low molecules, excellent in food use and industrial use, characterized by substantially no increase in viscosity even when cooled. It is the modified starch which has a property, and its manufacturing method.
[0002]
[Prior art]
The longest known of the modified starches is roasted dextrin, and there are products that have been called white dextrin, yellow dextrin, and British gum. In any case, the powdered starch is processed after chemical immersion, pre-drying, roasting, cooling, and conditioning, and the product is made by heating at a roasting temperature of 110 to 220 ° C. It is generally known that white dextrin is heated to around 120 ° C, yellow dextrin is heated to 150-200 ° C, and British gum is heated to 220 ° C. In general, the chemical solution is impregnated with a solution of hydrochloric acid, nitric acid, ammonia, sodium carbonate and the like, and dried to a water content of about 10% by preliminary drying.
[0003]
In general, the use of starch and processed products thereof can be said to be characterized by their high polymer properties and high viscosity. The main purpose of these conventional roasted dextrins is for industrial applications such as adhesives. In this case, there are many products that are more soluble than starch and have a relatively high viscosity. Low-viscosity products include processed starch that has been oxidized with sodium hypochlorite, but the viscosity increases as the temperature decreases after solution.
[0004]
[Problems to be solved by the invention]
The present invention was devised to improve the high molecular properties of starch in order to broaden such applications, and to provide products suitable for new applications. The purpose of the present invention is to combine starch with a salt solution. By improving the dextrin production method, which can be produced by simple operations that require only heat treatment, we have developed modified starch that is low-viscosity, non-reducing, less susceptible to Maillard reaction, and can be widely used in the food field, and its production method. There is to do. In particular, in applications as a powdering base for seasonings, soups, etc., whose demand has been increasing in recent years, it can be dissolved in as high a concentration as possible for pulverizing high-concentration extracts obtained by extraction of various animals and plants, A powder base having low viscosity, low reactivity with other components, and low moisture absorption after spray drying is desired. The present invention intends to provide a modified starch suitable for such use.
[0005]
In addition, the present invention provides a coating for the purpose of preventing the evaporation of surface moisture when freezing various food polishes and frozen foods, and further immersing the dried fish to dry the coating. In order to prevent oxidation during dry storage, it is intended to provide a modified starch that can be used for dissolution and soaking in an appropriate concentration, or spraying to adhere to the surface. To use starch as a material to be mixed with fried foods such as fried powder and flour, and industrially to increase the strength of gypsum board and for surface coating agents for papermaking The low viscosity is an indispensable element for uniformly dispersing and mixing with other components. Moreover, it is required to be a certain amount of polymer. For these purposes, oxidized starch is often used, but the modified starch produced by the method of the present invention is intended to be used in a wide range of these. In the present invention, the standard for the low viscosity is that the modified starch has a viscosity of 1/10 or less of the original starch, the viscosity can be measured at a solid concentration of 30%, the gelatinization temperature is low, The target was that the paste liquid had a low viscosity, and that the viscosity increase was small even when the temperature decreased, that is, the setback was small.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above-mentioned problems, the present inventor has obtained a starch mixture by heat-treating a wet mixture obtained by adding water in which an appropriate amount of salts are dissolved in various starches at a high temperature of about 130 ° C. for several hours. It has been found that the modified physical properties of the starch can be remarkably changed, and a novel modified starch suitable for the above-mentioned use can be produced.
[0007]
As changes in the physical properties of the modified starch, first, there are (1) a significant decrease in gelatinization temperature and viscosity. Gelatinization temperature and viscosity are measured by measuring changes in viscosity during heating and cooling using a constant speed heating and cooling automatic rotation viscometer known as RVA (Rapid Visco Analyzer), amylogram, etc. Temperature, maximum viscosity, maximum viscosity reached temperature, minimum viscosity, difference between minimum viscosity after maintaining maximum temperature and original maximum viscosity (breakdown), subsequent increase in viscosity during cooling, after cooling The difference (setback) between the viscosity and the minimum viscosity was measured. The modified starch of the present invention is characterized by such a low viscosity that the viscosity can be measured at a high concentration of 30% by weight and almost no setback. Next, (2) decrease in color developability (specific blue value) due to iodine, (3) almost no increase in reducing power, (4) increase in water solubility at 40 ° C, (5) at 40 ° C (6) Change in degree of gelatinization (α-degree), (7) Solization of paste liquid, change in gelation characteristics, etc. were observed.
[0008]
Next, regarding the change in molecular structure, (8) decrease in digestibility by amylase, (9) high degree of polymerization over tens of thousands recognized by measurement of chain length distribution by column fractionation using gel filtration agent of alkaline solution Decrease of molecular amylopectin and high molecular weight amylose with several thousand degree of polymerization, increase of low molecular weight with less than 1000 degree of polymerization, (10) side chain length of branched molecule due to medium pressure column fraction of digestion liquid by isoamylase From the measured results, the decrease in the long wavelength amylose segment (FrI) of the maximum wavelength of 620 nm, which is estimated to have a degree of polymerization of 100 or more, the long chain segment FrII (long B chain), the short chain segment FrIII (A chain and Approximately the same amount of increase (short B chain) was observed. Thus, it has become possible to produce modified starch having properties not known so far by simply adding a salt and subjecting it to a heat treatment without subjecting the starch to a special chemical reaction treatment.
[0009]
In addition, the present inventor described above that the kind of salt, the concentration, the pH of the wet mixture, the heat treatment temperature, and the heat treatment time that coexist at the time of the heat treatment greatly affect the properties of the modified starch and change them. It has been discovered that the physical properties of the modified starch change continuously.
Specifically, as factors that greatly affect the modification effect in this case (that is, the change in properties such as the viscosity of the product as described above), (1) the type of salt to be added, (2) the salt concentration to be added, It was found that (3) the heat treatment temperature and time, (4) the pH of the wet mixture during the heat treatment, and (5) the type of starch. By combining the processing conditions (1) to (4) and (5) the type of starch, modified starches having different degrees of modification can be produced. In an experiment using corn starch, the addition of a small amount of magnesium chloride compared to other starches showed a significant effect on viscosity reduction. This is because the pH of corn starch itself is in the acidic range of 4.3 to 4.7. I found out that this is the cause. Different results were obtained depending on the kind of salt to be added, the amount of the salt added, the pH, and the heating temperature and time. There was an interaction between these factors.
[0010]
The change in viscosity and gelatinization property changes so that the gelatinization start temperature decreases, the maximum viscosity decreases, the maximum viscosity attainment temperature also decreases, and does not show the maximum viscosity at all as the processing conditions progress. Further, the viscosity changes after heating and cooling, that is, the setback is hardly observed. At the same time, the solubility at 40 ° C. increases, the degree of swelling also increases, and the colorability (specific blue value) due to iodine decreases to 30% or less of the raw starch, while the increase in reducing power is very slight. Yes, it is 1% or less. Changes in properties such as viscosity, gelatinization, solubility, iodine coloration, specific blue value, etc. are also related to each other. As shown in FIG. 1, salts are added to potato starch at various concentrations. For the modified starch, when the specific blue value (iodine coloration) compared to the untreated starch is lowered to 30% or less, the maximum (peak) viscosity is drastically lowered, and the viscosity can hardly be measured. At the same time, the solubility at 40 ° C. tends to increase rapidly when the specific blue value falls below 45%. Although the specific blue value is greatly reduced, it is difficult to interpret that the hydrolysis has progressed substantially with little increase in reducing power.
[0011]
Furthermore, the change in molecular weight distribution was also confirmed as follows. An aqueous solution in which magnesium chloride to become 0.042 mol / kg starch (equivalent to 0.051 mol / kg dry matter starch) and hydrochloric acid to become 5.0 mmol / kg starch was mixed with potato starch, The moisture was 27% by weight and the pH was 4.5. Next, the wet mixture was uniformly spread on an aluminum vat to a thickness of about 1 cm, and a change in molecular weight distribution was measured for a sample heat-treated in a dry heat sterilizer at 135 ° C. for 5 hours.
First, molecular weight distribution was fractionated using a column filled with Toyopearl HW75S, which is a porous gel filter, using sample starch as an alkaline solution. The amount of sugar in each fraction was quantified, and at the same time, the absorbance at 540 nm and 660 nm due to the iodine reaction was measured and compared with a control sample that was simply heat-treated with water. As a result, the amylopectin of the polymer (degree of polymerization of tens of thousands or more) and the amylose section of the polymer (degree of polymerization of several thousand) are almost disappeared, and the number of the low molecular weight polymerized to a degree of polymerization of about 1,000 or less is increased. In this section, the absorbance at 540 nm was about twice as high as that at 660 nm, and it was revealed that the short chain was mainly composed of small molecules (FIG. 2). This fact is the cause of the change to low viscosity and low blue value.
[0012]
Furthermore, when the branch lengths were branched using isoamylase and the chain length distribution of the branched side chains was measured with Toyopearl HW55S-HW50S medium pressure column chromatography, the sample was found in the control sample. The FrI of the amylose section with a chain length of 100 or more almost disappeared, and then the IntFr with a chain length of 70 to 100, the FrII with a long chain section of 35 to 70, and the FrIII of a short chain section of 35 or less increased with the disappearance of FrI. It was shown that the long B chain, the short B chain, and the A chain increased, and the increased amount was the same as that of the amylose section that disappeared (see FIG. 3). Furthermore, for the sample where the branching point of the starch molecule was debranched with isoamylase, the ion exchange chromatography method in chromatography using DIONEX and the method in which the eluted carbohydrate was directly detected with a pulsed amperometric detector, When compared with the sample, low molecular side chains with a degree of polymerization of 3 to 5 were significantly increased in mol ratio of 44.4% for potato starch and 22% for corn starch compared to the control, and the degree of polymerization was 11 It was clarified that long side chains up to about ˜17 were reduced to about half.
These results mean that the long-chain segment was cleaved in the starch molecule and at the same time the short-chain branched molecules increased greatly, and the amount of reduction was reduced despite the decrease in iodine coloration. The increase in the viscosity at 40 ° C. and the increase in solubility at 40 ° C. are supported.
[0013]
Moreover, in the hydrolysis behavior by various enzymes, the result that the degradation limit by β-amylase was about 10% lower than that of the control starch was obtained. Moreover, even when pullulanase, a debranching enzyme, was shared, the degradation rate was about 50%. A low degree of degradation by glucoamylase was also obtained.
[0014]
From the above knowledge, the present inventors have completed a modified starch having completely new characteristics and a method for producing the same.
That is, according to the present invention, a wet mixture containing starch, moisture and 0.01 to 1.0 mol / kg starch is heated at a pH of 3 to 6 and a temperature of 110 to 150 ° C. for 1 to 8 hours. And the starch is corn starch, potato, sweet potato, tapioca, wheat, high amylose corn starch, or waxy corn starch, and the salt is a divalent metal salt of magnesium, zinc, manganese or calcium, sodium chloride or chloride Provided is a method for producing a modified starch having low viscosity and substantially no reducing power, characterized by being potassium.
Further, according to the present invention, a modified starch having a low viscosity and substantially no reducing power obtained by the above production method, the viscosity can be measured when a solution having a concentration of 30% by weight is obtained, and Provided is a modified starch characterized by almost no setback after heat gelatinization.
Since the modified starch of the present invention has the above-mentioned properties, it is a powdered substrate for foods, a surface treatment agent for foods, a raw material to be mixed with fried powdered or fried clothes, a reinforcing material for gypsum board, adhesion It is useful as an agent or a paper coating surface coating agent.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The actual operation of the production process of the modified starch of the present invention consists essentially of the following two steps. That is, a first step of uniformly mixing starch, salts, and moisture, and then a heat treatment within a range of 110 to 150 ° C. for 1 to 8 hours as a temperature at which the wet mixture is not colored by heat treatment. It consists of two steps.
[0016]
Below, each manufacturing process of this invention is demonstrated.
In the present invention, the salt addition concentration is expressed as mol / kg starch, which means the number of grams equal to the molecular weight of the salt added to 1 kg of starch. The starch as used herein means a commercially available starch containing equilibrium water content. For example, potato starch contains about 18% by weight of water. Since 0.5 mol salt / kg starch has a molecular weight of salt of 58.5, it becomes 29.25 g salt / kg starch. Since magnesium chloride hexahydrate has a molecular weight of 203.3, 20.33 g per kg of starch becomes 0.1 mol / kg starch, which is 2.033% w / w based on starch. If anhydrous magnesium chloride is used, the molecular weight is 95.3, so 0.953% w / w becomes 0.1 mol / kg starch.
[0017]
First, examples of the salts used in the present invention include divalent inorganic salts such as magnesium, zinc, manganese and calcium, in addition to monovalent salts such as sodium chloride (salt) and potassium chloride which are usually used in food production. It is done. Among divalent inorganic salts, the modification effect such as viscosity reduction is large in the order of magnesium>zinc>manganese> calcium, and the effect is large with the smallest amount of magnesium salt. The required amount of salt used is influenced considerably by the heating temperature, the type of starch, the pH at the time of treatment, etc., and varies depending on the degree of modification depending on the purpose. In general, salts in a proportion of 0.01 to 1.0 mol / kg starch are used for the production of the modified starch of the present invention. For example, if the pH of the wet mixture is 4.5 and the heat treatment temperature is 135 ° C., the above divalent metal salt is effective from 0.005 mol / kg starch, for example, 0.01 to 0.05 mol / kg starch is preferred. In the case of monovalent salts such as sodium chloride and potassium chloride, the modification effect is less than that of divalent metal salts, so 0.05-1.0 mol / kg starch, preferably 0.1-0.5 mol / kg The amount of starch used is preferred.
[0018]
The starch used in the present invention may be any conventionally known starch, such as corn starch, potato, sweet potato, tapioca, wheat, waxy corn starch, and high amylose corn starch that can be used industrially. . A considerable difference was observed in the decrease in viscosity due to the heat treatment of the present invention depending on the type of starch. Among the starches, waxy corn starch and corn starch had the greatest decrease in viscosity. This is because the pH of corn starch itself is low due to the production method, and it was found that the pH during the treatment greatly affects. It was confirmed that even when this low pH corn starch itself was heated at 130 ° C. without addition of salts, the maximum viscosity was slightly reduced, and only the contained acid had almost no modification effect due to heat treatment.
[0019]
As for the heating temperature during the heat treatment of the wet mixture, a temperature that does not color the wet mixture should be selected. A correlation is found between the salt addition concentration and the temperature, and a high salt concentration requires a low temperature and a low salt concentration requires a high temperature. Therefore, the higher the salt concentration and the higher the temperature, the easier it is to color. Considering avoiding heat coloring of starch, the heating temperature is practically 110 to 150 ° C., and 135 ° C. is the standard. In the case of batch type, uniform heating treatment is difficult unless the wet mixture is spread thinly and heated. For mass production, a jacket and a stirring blade with a heating device, or a mixing / heating type with a heating pipe attached. It is preferable to use the apparatus. The heating time varies depending on the heating method, but 1 to 8 hours is practical, and about 5 hours was standard.
[0020]
Regarding the difference in starch type, the untreated raw potato starch has a viscosity measurement result at a concentration of 10% by weight. The gelatinization start temperature is 60.8 ° C, the maximum viscosity attainment temperature is 71.7 ° C, the maximum viscosity is 794 SNU (Stirring Number of Unit), minimum viscosity 190 SNU, breakdown 604 SNU, cooling viscosity 247 SNU, setback 57 SNU. Similarly, in untreated corn starch, they were 72.4 ° C., 89.95 ° C., 300 SNU, 106 SNU, 194 SNU, 106 SNU, and 148 SNU, respectively. In the present invention, low viscosity means that the viscosity can be measured at a concentration of 30% by weight, the maximum viscosity is 500 SNU or less, and there is substantially no setback.
[0021]
Taking corn starch as an example, when magnesium chloride is used, it is possible to measure viscosity at 30 wt% concentration by heat treatment at 135 ° C for 5 hours with a small amount of 0.008 mol / kg starch, and cooling with little setback. However, the viscosity is reduced at 130 ° C., but the increase in viscosity and setback due to heating are large. If the amount of magnesium chloride is 0.013 mol / kg starch or more even under conditions of heating at 130 ° C. for 5 hours, the modification progresses and the viscosity cannot be measured. In the heat treatment at 135 ° C. for 5 hours, the same is true at 0.01 mol / kg starch or more. Further, the solubility at 40 ° C. is increased, and the specific blue value of iodine coloration is 30% or less of that of untreated raw starch. However, the increase in reducing power is 2% or less, and it is considered that hydrolysis has not progressed much.
[0022]
The pH of corn starch is usually around 4.5 due to the presence of acids brought in from the manufacturing process. In order to investigate the possibility of this low pH, when using a corn starch having a pH of 8.3 obtained by washing a commercially available corn starch with a large amount of dilute alkaline solution, even when using 0.02 mol / kg starch of magnesium chloride, 10 wt. It was revealed that there was no effect when the pH during the heat treatment was in a slightly alkaline state to a degree that the viscosity was slightly lower than that of untreated corn starch compared with the% concentration. This is considered to be affected by the dissolution of magnesium. When 0.02 mol / kg starch of magnesium chloride and hydrochloric acid are added to this washed fine alkali corn starch to adjust the pH to 4.9, the viscosity is low enough to measure the viscosity at a concentration of 30% by weight, and the maximum viscosity is 80 SNU. Even when cooled, almost no increase in viscosity was observed.
[0023]
Next, when potato starch is used as a raw material, the gelatinization temperature is low, the maximum viscosity is high, the breakdown is large, the pH of itself is close to neutrality, and the addition amount of magnesium chloride must be increased. There was no denaturation effect. If the amount of magnesium chloride added is 0.042 mol / kg starch when heated at 135 ° C. for 5 hours, the maximum viscosity becomes low at a concentration of 30% by weight. The breakdown is large, the viscosity becomes so low that the viscosity cannot be measured after heating, the viscosity does not increase after cooling and no setback is observed. It was also confirmed that the paste was transparent and kept transparent at room temperature and 40 ° C. even after 1 week, and that the viscosity was hardly increased, that is, it was stable against aging. In this case, at the same time when adding magnesium chloride, 0.003 to 0.0075 mol / kg starch of hydrochloric acid is added to lower the pH of the wet mixture starch to 4 to 5.3. This shows the same tendency in the case of sweet potato (example pH 5.6) and tapioca starch (example pH 6.8).
[0024]
Therefore, in the case of potato, sweet potato, tapioca and other starches that are close to neutral pH, it is possible to reduce the salt addition amount by making the pH of the wet mixture not more than 5.3 by coexisting acid. Yes, if you want something with a lower viscosity corresponding to the purpose of denaturation or less increase in viscosity during cooling, lowering the pH within the range allowed for the purpose of use of the modified starch will increase the denaturation effect. The amount of salt added can be reduced. This greatly affects the taste of the modified starch product. Although the kind of acid to be used is not particularly limited, an acid suitable for the intended use of the modified starch is selected and used. Citric acid is suitable for edible use.
[0025]
In the case of sweet potato, the pH is about 5.6 to 5.8, the magnesium chloride is 0.042 mol / kg starch, and the maximum viscosity appears at 30% by weight concentration even after heat treatment at 135 ° C for 5 hours. However, if the starch is heated at the same pH of 4.8 by adding 0.003 mol / kg starch of hydrochloric acid, the viscosity of the starch can be increased by heating or cooling after heating. Not recognized, that is, the modified starch has a small setback.
[0026]
In the case of tapioca starch, the maximum viscosity is considerably reduced at 0.042 mol / kg starch under the conditions of heat treatment at 135 ° C. for 5 hours at pH 6.8, but the viscosity increases markedly with cooling, that is, the setback is large. In this case, however, when 0.003 mol / kg starch of hydrochloric acid was added and the pH was lowered to about 4.5, the starch was modified to a starch having a small setback.
[0027]
In the mixing of the salt (and acid) and starch in the first step, for example, the salt is dissolved in an appropriate amount of water, and when necessary, the pH is adjusted by adding an acid solution in advance. Mixed. Further, the minimum amount of water required for the uniform mixing of both is sufficient. Various known mixers can be used for the mixing, and no special specifications are required.
[0028]
Although it is heat processing of a 2nd process, naturally, it is necessary for a wet mixture to be heat-processed uniformly. Whether the heating time is agitated and mixed during the heat treatment or whether it is left standing depends on the heat treatment conditions such as the type of heat source, but if you always want to obtain modified starch with a certain quality, consider the heating method for each device Must. The required heating time varies depending on the efficiency of heat transfer, but since the heat transfer efficiency is not good because there is little moisture, at least 4 to 5 hours are required for stationary heating. For example, when potato starch is mixed with 0.042 mol / kg starch of magnesium chloride and heated at 135 ° C., the viscosity is high at 30% by weight in 3 hours and cannot be measured. Denatured to the extent that the viscosity can be measured. In the case of a stirring and mixing type efficient apparatus, heating in a relatively short time is sufficient.
[0029]
The modified starch of the present invention is shown by the following examples, but the present invention is not limited thereto.
[0030]
【Example】
Example 1
As a mixer, a mortar machine having a diameter of 36 cm and a deepest part of 18 cm made by Bibun Machine was used. To 500 g of commercially available corn starch (water 13%, pH 4.7), add a solution of 0.008 to 0.066 mol / kg starch dissolved in 110 ml of water with magnesium chloride hexahydrate mixed, and mix for about 20 minutes. A mixture was obtained. The calculated water content was 28.68% by weight, but was 26-27% by weight after mixing.
[0031]
This wet mixture is divided into 3 sections with a 26 x 19 x 5 cm stainless steel vat with aluminum foil and 110 g of wet mixture is spread to about 1 cm in one section, and each is adjusted to 125 ° C, 130 ° C and 135 ° C. The heat treatment was performed for 5 hours in the blower-type incubator. When magnesium chloride was in a high concentration and at a high temperature, a slight coloration was observed, but there was almost no change in the microscopic appearance. Various measurement results are shown in Tables 1 and 2. Viscosity measurement is the result of 30% concentration. As is apparent from these tables, the 135.degree. C. heat treatment shows a remarkable viscosity reduction effect even at a low concentration of 0.08 mol / kg, and 0.013 mol / kg starch increases the solubility at 40.degree. C. to 77%. No increase in viscosity was observed even when continued, and the viscosity did not increase at all even after cooling at 95 ° C. for 5 minutes. Similar results were obtained at a high concentration of 0.042 mol / kg starch or higher at 125 ° C. The combination of magnesium chloride addition concentration and heating temperature gave the specific blue value of iodine coloration, including viscosity, and the solubility at 40 ° C. It has become clear that various physical properties can be changed over a wide range. The results are shown in the table below.
In addition, as for the digestibility by β-amylase, when modified starch heated at 130 ° C. with addition of 0.042 mol / kg starch of magnesium chloride and starch just heated under the same conditions without addition of salt, the salt-added starch was compared. The value was about 11% lower.
[0032]
[Table 1]

[0033]
[Table 2]

[0034]
Example 2
As a mixer similar to Example 1, a stone mill type, 3 stir bar type crusher with a diameter of 36 cm and a deepest part of 18 cm was used. The required amounts of magnesium chloride hexahydrate, zinc chloride, manganese chloride and calcium chloride were dissolved in 70 ml of water in 500 g of commercially available potato starch from Hokkaido (water content 18%, pH 6.7) and added with stirring. The calculated water content was 28.7% by weight, but after stirring and mixing for 20 minutes, a small amount evaporated to 26-27% by weight.
[0035]
Each wet mixture was subjected to a heat treatment at 135 ° C. for 5 hours in a fan-type incubator with 26 × 19 × 5 cm stainless steel bats divided into three sections and 110 g of the wet mixture thinly spread to a thickness of about 1 cm. Various properties were compared for this heat-treated starch. The viscosity characteristics are shown in the table below.
[0036]
[Table 3]

[0037]
[Table 4]

[0038]
From the results in these tables, it has been clarified that the salt addition concentration requires a higher concentration than corn starch, and there is a significant difference depending on the type of salt.
Magnesium chloride was 0.042 mol / kg starch, and zinc chloride was 0.062 mol / kg starch. The viscosity measured at a concentration of 30% by weight was 500 SNU or less, but calcium chloride was 0.062 mol / kg starch. Sufficient viscosity reduction was not recognized. However, when measured at a concentration of 10% by weight, a significant decrease in viscosity was observed as compared with the untreated one, and the maximum viscosity was 50 SNU or less at 0.042 mol / kg starch, and the viscosity decreased by further heating. It was confirmed that there was almost no increase in viscosity thereafter (that is, there was no setback).
[0039]
Example 3
Results obtained when heat-treated at 135 ° C. for 5 hours, a potato starch was added to potato starch with a required amount of salt dissolved in water and further added with hydrochloric acid to lower the pH. Is shown in the table below.
[0040]
[Table 5]

[0041]
[Table 6]

[0042]
From the results in these tables, 0.003, 0.005, 0.0075 mol / kg starch of hydrochloric acid was added to adjust the pH of the salt-mixed wet starch to 5.1, 4.6, 4.0, respectively. The lowering effect and other modification effects are clearly increased, and calcium chloride, which was the least effective among the divalent salts in Example 2, also has a practical modification effect at 0.042 mol / kg starch, due to viscosity reduction and iodine coloration. It was found that specific blue value, solubility at 40 ° C., etc. changed remarkably.
[0043]
Example 4
The same operation as in Example 2 was performed on sweet potato starch. Magnesium chloride 0.042 mol / kg starch was added to 500 g of commercially available sweet potato starch (moisture 14.6%, pH 5.6) and 99 ml of water, and 0.003 mol / kg starch of hydrochloric acid was added thereto to adjust the pH to 4.8. The wet mixture (calculated water value 28.7%, measured value 27.9%) was heat-treated at 135 ° C. for 5 hours. The results are shown in the following table.
[0044]
[Table 7]

[0045]
From the results in this table, the effect of adding magnesium chloride is greater when hydrochloric acid is added and the pH is lowered to 4.8, similar to potato starch, the gelatinization temperature is lower by about 15 ° C., the maximum viscosity is lower, and There was almost no setback and the specific blue value of the iodine reaction decreased to about 37%, but the solubility became starch which did not increase as much as potato starch. When magnesium chloride was added in the state of pH 5.6, the maximum viscosity decreased and the breakdown was considerably large when heating was continued, but it was characterized by an increase in viscosity accompanying cooling, that is, a large setback.
[0046]
Example 5
The same operation as in Example 2 was performed on tapioca starch. 0.042 mol / kg starch of magnesium chloride was dissolved in 500 g of tapioca starch (water 12.3%, pH 6.8) and 115 ml of water, and 0.003 mol / kg starch of hydrochloric acid was added thereto to adjust the pH to 4.5. The wet mixture (calculated moisture value 28.7%, measured value 28.3%) was heat-treated at 135 ° C. for 5 hours. The results are shown in the following table.
[0047]
[Table 8]

[0048]
As a feature of tapioca starch, the addition of only 0.042 mol / kg of magnesium chloride reduces the maximum viscosity considerably to about 15%, but the setback is large, and the reduced viscosity after heating significantly reduces the viscosity. It rose and became higher than the maximum viscosity. However, by adding an acid and heat-treating it, the starch was modified to starch having a low gelatinization temperature, a maximum viscosity and almost no viscosity after cooling.
[0049]
Example 6
In the same manner as in Example 2, 0.7305 g (0.05 mol / kg starch) of sodium chloride, 7.305 g (0.5 mol / kg starch), 22.5 ml of water, and 25 ml of 1 mmol hydrochloric acid were dissolved in 250 g of potato starch. The wet mixture was heated at 135 ° C. for 5 hours. The pH of this product was 4.1. The results are shown in the following table.
[0050]
[Table 9]

[0051]
From the results in this table, it is considered that when salt is added as a salt, the modification effect cannot be expressed unless a considerable amount is added compared to magnesium chloride.
[Brief description of the drawings]
FIG. 1 shows the relationship between the maximum viscosity by RVA and the solubility at 40 ° C. of a modified potato starch and the specific blue value.
FIG. 2 shows a molecular weight distribution by gel filtration column analysis of magnesium chloride-modified potato starch.
FIG. 3 shows chromatography on a medium pressure column of molecules cleaved with a debranching enzyme of magnesium chloride-modified potato starch.

Claims

Including a step of heat-treating a wet mixture containing starch, moisture and salts in a proportion of 0.01-1.0 mol / kg starch at a pH of 3-6 and a temperature of 110-150 ° C. for 1-8 hours, and The starch is corn starch, potato, sweet potato, tapioca, wheat, high amylose corn starch, or waxy corn starch, and the salt is magnesium, zinc, manganese or calcium divalent metal salt, sodium chloride or potassium chloride A method for producing modified starch having low viscosity and substantially no reducing power.

The method for producing a modified starch according to claim 1, wherein the pH is 4-5.

The method for producing a modified starch according to claim 1 or 2, wherein the salt is magnesium chloride.

The method for producing modified starch according to claim 3, wherein the ratio of magnesium chloride is 0.01 to 0.05 mol / kg starch.

The method for producing a modified starch according to claim 1 or 2, wherein the salt is sodium chloride.

The method for producing a modified starch according to claim 5, wherein the ratio of sodium chloride is 0.05 to 1.0 mol / kg starch.

The modified starch having a different degree of modification according to a combination of various conditions including the kind of starch and the pH of the wet mixture, the kind and concentration of the salt, and the heating temperature and time. Method for producing modified starch.

A modified starch having a low viscosity and substantially no reducing power obtained by the production method according to any one of claims 1 to 7, wherein the viscosity can be measured when the solution is made into a solution having a concentration of 30% by weight. A modified starch characterized by having a setback after heat gelatinization.