【発明の詳細な説明】[Detailed description of the invention]
本発明は納豆加工食品、詳しくは表面が乾燥蛋
白被膜で被覆され、その保存性、栄養価、風味等
の改善された新しい納豆加工食品に関する。
納豆は、一般に蒸煮した大豆に納豆菌を植菌し
て醗酵させることにより得られ、安価で且つ優秀
な植物性蛋白源である原料大豆に起因した豊富な
栄養成分が納豆菌の蛋白分解酵素や糖質分解酵素
によりほどよく消化されており、最近豆乳や豆腐
等と共に優れた栄養価を有する食品として注目さ
れている。しかるにこれは水分含量が60重量％
（以下同じ）前後と高く、しかも醗酵産物であり、
納豆菌その他の微生物の繁殖に適しており保存期
間が非常に短いという致命的欠陥を有している。
またこれは糸引納豆とも呼ばれるように、乾燥重
量換算で約２％の粘稠質物を含有しており、それ
特有の風味のために嗜好性に偏りがあり、取扱い
性にも不利がある。従つて従来より上記納豆を乾
燥してその保存性を改善する試みが種々なされて
いるが、単なる乾燥操作による水分含量の低下の
みでは保存性の改善は尚不充分である。即ち納豆
は吸湿性が著しく、乾燥後比較的速やかに当初の
べとつきを発現し、また容易に微生物による腐敗
乃至は納豆菌の過剰分解によるアンモニア臭発生
に至る。この傾向は乾燥品を密封包装する場合に
も、充分には回避できない。乾燥による水分含量
を３％を下回るものとすれば保存性は満足なもの
となるが、この場合得られる乾燥品は硬すぎて食
用に供し難くなり、これを粉末化すれば上記吸湿
性が更に大きくなり、いずれも実用的でない。
本発明者らは、上記現状に鑑み、従来の保存性
改善法とは全く異なつて、納豆の吸湿性を消失乃
至抑制することによつて、その保存性を向上させ
る観点から鋭意研究を重ねた。その結果納豆を食
用できるに充分な柔らかさを保持する水分含量と
なるように半乾燥させると共に、この半乾燥納豆
表面を蛋白被膜により被覆する時には、所望の非
吸湿性を具備し、保存性の顕著に改善された納豆
加工食品が収得され、しかも該食品は従来のこの
種納豆加工食品には見られない独特の風味等を有
するものとなり、殊に糸引性、ねばり、べとつ
き、納豆臭等が緩和された巾広い嗜好性を有する
ものとなり、更に栄養学的にも一層改善されバラ
ンスのとれたものとなることを見い出した。本発
明は上記新しい知見により完成されたものであ
る。
即ち本発明は、水分含量３〜25重量％の乾燥納
豆と、該乾燥納豆表面に形成された乾燥蛋白被膜
とから成る納豆加工食品及びその製造方法に係
る。
本発明の納豆加工食品は、そのまま食用に供す
るに充分な柔らかさを保持する水分を残存させて
おり、しかもこの水分含量にも拘らず、見かけ上
の水性活性値が極めて低く微生物による腐敗の危
険のない長期保存性を有しており、また吸湿性が
実質的に防止され、ねばりやべとつきを生じな
い。事実本発明納豆加工食品は、30℃下に、密封
条件及び100％R.H.湿度条件のいずれで保存する
場合も、実に１ケ月に亘つて製造直後の品質を保
持しており、その外観、風味等に何らの変化（劣
化）を認め得ない。かかる優れた品質を長期に亘
つて保持する理由は、現在尚明らかではないが、
本発明食品表面に形成されている乾燥蛋白被膜
が、空気や水分等の流通を抑制乃至遮断し、納豆
の吸湿によるねばりやべとつきが防止され、納豆
臭の発散も抑制され、更に納豆内部に残存する微
生物の繁殖が抑制され、また外部からの微生物の
侵入も阻止されるためと考えられる。
また本発明の納豆加工食品は、上記の通り吸湿
性がなく、糸を引かないため取り扱いが容易であ
り、これがねばり、べとつき、納豆臭等の緩和と
相埃つて嗜好性を偏らせることなく、いつでもど
こでも気軽に多数の人々に賞味され得るものであ
る。
更に本発明食品は、その被膜として卵白を用い
れば大豆蛋白の栄養的欠点とされる合硫アミノ酸
含量及び蛋白価の低さを、該卵白により補なうこ
ともでき、その栄養学的価値も非常にバランスが
とれ且つ優れたものにすることができる。
以下本発明の納豆加工食品を、その製造法によ
り詳述する。
本発明方法においては、まず納豆を乾燥して、
その水分含量を３〜25重量％、好ましくは５〜20
重量％、特に好ましくは10〜20重量％の範囲とす
る。ここで水分含量は、カールフイツシヤー法に
より測定されるものとする。原料とする納豆は、
通常の方法例えば蒸煮大豆に納豆菌を作用させて
得られる糸引納豆を有利に使用できるが、これに
限定されることなく例えば予め蒸煮大豆の段階で
加塩調味され、以後常法に従い製造された加塩納
豆、糸引納豆に更に適当な酵素を作用させて栄養
成分の利用率を向上させたもの、上記各種納豆を
擂潰した納豆、引割り納豆等をいずれも使用する
ことができる。上記原料納豆の乾燥は、例えば通
常の真空乾燥、熱風乾燥等により実施できる。そ
の際の乾燥条件は任意に選択でき特に限定されな
いが、得られる乾燥品の水分含量を３〜25重量％
の範囲とすることが重要である。水分含量が３重
量％を下回るものとなるまで強乾燥すれば、乾燥
品自体が硬くなりすぎ、そのままで食用に供する
ことが困難となる。また水分含量が25重量％を上
回るように乾燥したものでは、まだ互いにくつつ
き合うべとつきを有しており、好ましくない。尚
上記所定の水分含量にしたものでも、これらはそ
の水分含量により若干異なるが、いずれも長時間
放置により、たとえ完全閉封に近い状態としてお
いても、経時的にべとつきを生じ、互いにくつつ
き合う傾向がある。したがつて本発明では、上記
乾燥後、比較的速やかに、通常約24時間以内、好
ましくは約５時間以内に引き続く蛋白液による被
覆処理を行なうのが望ましい。
上記乾燥納豆の蛋白液による被覆処理におい
て、蛋白液としては、例えば生卵より分離した卵
白、市販の卵白液又は市販卵白粉末を水に適当濃
度に溶解したものを有利に利用することができる
が、これら卵白液に限らず、例えば市販大豆蛋白
や市販カゼインナトリウム等の適当な蛋白を適宜
水に溶解した液やゼラチン等の加温溶解液等をも
略同様に用いることができる。また上記各種蛋白
液には、必要に応じて例えば醤油、こしよう、み
りん、とうがらし等の調味料やデキストリン、グ
アーガム等の食品添加剤等を添加溶解させておく
こともできる。これら添加剤の配合量は、本発明
の乾燥蛋白被膜形成による特性を阻害しない範
囲、通常蛋白固形分重量と等量までとするのが好
ましい。かかる添加剤の配合によれば、得られる
納豆加工食品に種々の味付けができ、その食性殊
に味覚を一層改善することができる。
上記蛋白液による乾燥納豆表面の被覆は、蛋白
液中に乾燥納豆を浸漬する方法、乾燥納豆に蛋白
液を塗布する方法、乾燥納豆上に蛋白液を滴下し
て塗す方法等の各種方法により行ない得る。蛋白
液の使用量は、乾燥納豆表面に連続した被膜が形
成される限り特に制限はないが、通常固形分換算
量で乾燥納豆100ｇ当り約２〜20ｇ、好ましくは
約５〜10ｇとするのが好ましい。
上記蛋白液被覆に引き続く乾燥操作は、形成さ
れた蛋白被膜が乾燥される適宜の方法例えば真空
乾燥、熱風乾燥等により実施される。この乾燥操
作を真空乾燥により行なう場合、得られる食品の
表面は、つやのないものとなり、また熱風乾燥に
より行なう場合、得られる食品表面はつやのある
光沢性を有するものとなる傾向がある。尚本発明
方法においては、上記により形成される乾燥蛋白
被膜をより均一且つ完全な連続被膜とするため
に、上記被覆処理及び乾燥処理を繰返し複数回行
なうこともできる。
また本発明方法においては、更に必要に応じて
上記蛋白液被覆及び乾燥処理に引き続いて、通常
食品加工分野で行なわれているパフ処理を行なう
こともでき、これによれば最終製品とする納豆加
工食品にソフトな食感特に良好な歯ざわりを付与
することができる。上記パフ処理は通常の方法に
従い、例えば所謂バクダンと呼ばれるバツチ式パ
フ機やロータリーバルブ式の連続パフ機を用いて
行なうことができる。
かくして本発明の納豆加工食品を得る。得られ
た食品は、後記実施例において詳述するように、
長期に亘る保存性、非吸湿性、高含硫アミノ酸価
等を有しており、そのままでスナツク風食品とし
て多数の人に賞味される。
以下本発明納豆加工食品の製造例を実施例とし
て挙げる。尚各例中水分量は、試料１〜1.5ｇを
乳鉢で適当に破砕後、メタノールで30分抽出し、
メトローム社製「633カール フイツシヤー オ
ートマツト」にて測定した。
実施例 １
精選、洗滌後の大豆60Kgを加圧釜で1.2Kgで20
分間蒸煮し、約130Kgの蒸煮大豆とし、これに市
販納豆菌５ｇを２の煮沸消毒した滅菌水に懸濁
させた液を、蒸煮大豆の温度が80℃に下つた時添
加し、よく撹拌した。これを100ｇずつ小分けし
40℃の室に入れ、10時間保つた。品温が50℃に達
したので室の温度を30℃の調節空気を入れて冷し
た。５時間のち出来た納豆を冷蔵庫に入れて保存
した。この納豆の分析値は蛋白質16.6ｇ、脂質
10.0ｇ、糖質10.2ｇ、繊維2.2ｇ、灰分2.4ｇ、水
分58.6ｇであつた（100ｇあたりの含量）。またそ
の蛋白質中の含硫アミノ酸含量は、メチオニン13
重量％、システイン18重量％及びトリプトフアン
13重量％であり、その蛋白価は59であつた。以後
の実施例ではすべてこの納豆を用いた。
納豆200ｇを真空乾燥機に入れ、棚温度90℃、
真空度15トールにて、５時間乾燥した。この時の
納豆重量は100ｇであり、水分は16％であつた。
次にこの全量を生卵より分離した卵白液30ｇとし
よう油３ｇを混ぜた液に浸し、よく混ぜたのち、
再び真空乾燥を２時間行なつた。さらにこれに卵
白液30ｇとしよう油３ｇとを混ぜ合せ３時間乾燥
したのち、更に卵白液30ｇに浸し、３時間乾燥し
て本発明の納豆加工食品102ｇを得た。このもの
の水分は15％であつた。
得られた製品の蛋白質量は40.6ｇ（100ｇあた
りの含量）であり、そのうちメチオニンは18重量
％、システインは22重量％及びトリフトフアンは
14重量％であり、蛋白価は82に向上した。
また得られた製品の水分活性値を、東京芝浦電
気社製のAW測定器AW−351を用いて測定した
結果を第１表に示す。
更に得られた製品を30℃及び50℃下に密封条件
及び相対湿度100％R.H.の条件下にそれぞれ放置
し、放置安定性を試験した所、80℃条件下ではい
ずれも１ケ月間何らの変化も認められなかつた。
また50℃条件下では14日間は何らの変化も認めら
れず１ケ月では外観上やや黒ずむ場合もあつた
が、製造直後の非吸湿性、風味等に変化は見られ
なかつた。更にすべての製品は上記試験期間中及
び試験後も、納豆臭が非常に緩和されており、ま
た大豆の過剰醗酵によるアンモニア臭は全く認め
られなかつた。
実施例 ２
納豆200ｇを熱風乾燥機に入れ、85℃の熱風で
２時間30分乾燥した。この時の納豆の重さは97.2
ｇであり、水分は13.5％であつた。この全量を市
販卵白粉末３ｇ、水３ｇ及びしよう油３ｇを混ぜ
た液とよく混合したのち、再び熱風乾燥を30分間
行なつた。次に上記卵白混合液に0.5ｇのブラツ
クペツパーを添加した液に混ぜ、よく撹ぜたの
ち、１時間熱風乾燥を行なつて、本発明の納豆加
工食品95.8ｇを得た。このものの水分は11％であ
つた。
得られた製品の物性は、実施例１で得た、それ
と略同様であつた。また該製品の水分活性値及び
放置安定性を実施例１と同様にして測定した結果
を第１表及び第２表に示す。
実施例 ３
納豆500ｇを熱風乾燥機に入れ、85℃の熱風で
３時間乾燥した。この時の納豆の重さは242ｇで
あり、水分は13％であつた。この全量を市販卵白
粉末９ｇ、水９ｇ、しよう油7.5ｇを混ぜた液を
からめ、棚温度85℃、真空度15トールの条件下で
２時間真空乾燥を行なつた。さらに同じ組成の卵
白混合液とからめた後再び同条件で３時間真空乾
燥を行なつて本発明の納豆加工食品239ｇを得た。
このものの水分は10.5％であつた。
また得られた製品は、実施例１で得たそれと略
同様の含硫アミノ酸含量を示しバランスのとれた
高栄養価を有しており、長期保存性、非吸湿性、
風味等を有していた。このものの水分活性値を実
施例１と同一の試験により測定した結果を第１表
に示す。
実施例 ４
納豆200.1ｇをタバイハイ−テンプオーブン
（HIGH−TEMP OVEN HPS−222）で、温度
85℃で４時間乾燥して99.9ｇの乾燥納豆を得た。
この時の水分は11.1％であつた。これを光陽機械
製作所製のバツトライス機No.1型で温度125℃、
圧力2atmで処理時間４分間でパフ処理を行なつ
て95.3ｇのパフ処理納豆を得た。このものの水分
は６％であつた。次にこれを卵白粉末３ｇを３ｇ
の水に溶かしたものと、３ｇのしよう油をまぜた
液に浸し、よく撹拌したのち、上記オーブンで85
℃にて20分間乾燥し、再びこの操作をくり返し
た。次に卵白粉末３ｇを水６ｇに溶かした液を付
着させ、上記オーブンで40分間乾燥を行い本発明
品102.7ｇを得た。本品は水分５％と低かつたが、
歯ごたえは軽く容易にかみくだくことが出来た。
外観は元の大豆の大きさを保ち、乾燥による縮み
が全くなかつた。その他の物性は実施例１〜３の
ものとほぼ同様であつた。その水分活性値の試験
結果を第１表に示す。
実施例 ５
納豆364.1ｇを通風乾燥機にて、風温85℃で２
時間乾燥し、209ｇの乾燥納豆を得た。このもの
の水分は25.0％であつた。これを実施例４と同じ
パフ操置で温度150℃、圧力2atmで処理して、
191ｇのパフ納豆を得た。この水分は15％であつ
た。これに水20.2ｇにカゼインナトリウム4.6ｇ、
しよう油9.2ｇ及びグラニユー糖１ｇを加えて溶
かした液を均一に塗布し通風乾燥機で２時間乾燥
し本発明の納豆加工食品179.8ｇを得た。このも
のの水分は5.7％であつた。
このものは50℃加温室にて１週間放置してもね
ばりや、粒同士がくつつき合うことはなかつた。
又30℃で100％湿度下に１週間放置したものも吸
湿のため少し柔らかくなつたが、粒同士がくつつ
き合うことはなかつた。いずれも食して異状は認
められなかつた。その水分活性値を実施例１と同
様にして求めた結果を第１表に示す。
実施例 ６
納豆193.4ｇを85℃の通風乾燥機で３時間乾燥
し101.3ｇの乾燥納豆を得た。これを実施例４及
び５と同様にしてパフ処理して95.2ｇのパフ納豆
を得た。これに大豆タンパク、水及びしよう油が
１：９：２の組成の液35.2ｇをよく表面に塗布
し、通風乾燥を１時間20分間行ない本発明品の納
豆加工品95.4ｇを得た。水分は６％であつた。こ
の製品は実施例５で得られたそれと同等の性質を
有していた。その水分活性値を実施例１と同様に
して求めた結果を下記第１表に示す。
尚第１表及び第２表には比較のため本発明の卵
白液による被覆処理を行なわない以外は実施例２
と同様にして得た納豆についての試験結果を対照
品として併記する。
The present invention relates to a natto processed food, and more particularly to a new natto processed food whose surface is coated with a dry protein film and whose preservability, nutritional value, flavor, etc. are improved. Natto is generally obtained by inoculating steamed soybeans with Bacillus natto and fermenting it, and the rich nutritional components derived from the raw soybean, which is an inexpensive and excellent source of vegetable protein, are combined with the proteolytic enzymes and enzymes of Bacillus natto. It is well digested by carbohydrate-degrading enzymes, and has recently attracted attention as a food with excellent nutritional value, along with soy milk and tofu. However, this water content is 60% by weight.
(The same applies hereafter) It is higher than before and after, and it is a fermentation product,
It is suitable for the propagation of Bacillus natto and other microorganisms, and has a fatal flaw in that it has a very short shelf life.
In addition, it contains about 2% viscous material on a dry weight basis, which is also called Itohiki natto, and its unique flavor makes it unbalanced in palatability, and it is also disadvantageous in handling. Therefore, various attempts have been made to improve the storage stability of the natto by drying it; however, simply reducing the moisture content by drying is still insufficient to improve the storage stability. That is, natto is highly hygroscopic and becomes sticky relatively quickly after drying, and easily leads to decomposition by microorganisms or the generation of an ammonia odor due to excessive decomposition of natto bacteria. This tendency cannot be sufficiently avoided even when dry products are sealed and packaged. If the moisture content by drying is less than 3%, the storage stability will be satisfactory, but the dried product obtained in this case will be too hard and difficult to eat, and if it is powdered, the above hygroscopicity will be further improved. Both are large and impractical. In view of the above-mentioned current situation, the present inventors have conducted extensive research with a view to improving the preservability of natto by eliminating or suppressing its hygroscopicity, which is completely different from conventional methods of improving preservability. . As a result, the natto is semi-dried to a moisture content that maintains sufficient softness to be eaten, and when the surface of this semi-dried natto is coated with a protein film, it has the desired non-hygroscopic property and has a long shelf life. A markedly improved natto processed food was obtained, and the food had a unique flavor not found in conventional natto processed foods of this kind, and in particular had reduced stringiness, stickiness, stickiness, natto odor, etc. It has been found that the product has a relaxed and wide palatability, and is nutritionally improved and well-balanced. The present invention was completed based on the above new findings. That is, the present invention relates to a processed natto food consisting of dried natto having a moisture content of 3 to 25% by weight and a dry protein coating formed on the surface of the dried natto, and a method for producing the same. The processed natto food of the present invention retains enough moisture to remain soft enough to be eaten as is, and despite this moisture content, the apparent aqueous activity value is extremely low and there is a risk of spoilage due to microorganisms. It has a long shelf life without any moisture, is substantially prevented from absorbing moisture, and does not become sticky or sticky. In fact, the processed natto food of the present invention maintains its quality immediately after production for a month, whether stored at 30°C in sealed conditions or under 100% RH/humidity conditions, and its appearance, flavor, etc. No change (deterioration) can be observed. The reason for maintaining such excellent quality over a long period is currently not clear, but
The dry protein film formed on the surface of the food of the present invention suppresses or blocks the flow of air and moisture, prevents the natto from becoming sticky and sticky due to moisture absorption, and suppresses the release of natto odor, which also remains inside the natto. This is thought to be due to the fact that the growth of microorganisms that occur is suppressed, and the invasion of microorganisms from the outside is also prevented. In addition, as mentioned above, the processed natto food of the present invention is easy to handle because it is not hygroscopic and does not draw strings. It can be easily enjoyed by many people anytime and anywhere. Furthermore, if the food of the present invention uses egg white as its coating, the nutritional disadvantages of soybean protein, such as low sulfurized amino acid content and low protein value, can be compensated for by the egg white, and its nutritional value also increases. It can be very balanced and excellent. The natto processed food of the present invention will be explained in detail below by its manufacturing method. In the method of the present invention, first, natto is dried,
Its moisture content is 3-25% by weight, preferably 5-20%
% by weight, particularly preferably in the range from 10 to 20% by weight. Here, the moisture content is measured by the Karl Fischer method. The natto used as raw material is
It can be advantageously used, for example, itobiki natto obtained by treating steamed soybeans with Bacillus natto, but is not limited thereto. Any of the following can be used: natto, stringy natto that is further treated with a suitable enzyme to improve the utilization rate of nutritional components, natto obtained by crushing the various types of natto mentioned above, strained natto, and the like. The raw material natto can be dried, for example, by ordinary vacuum drying, hot air drying, etc. The drying conditions at that time can be arbitrarily selected and are not particularly limited, but the moisture content of the dried product obtained is 3 to 25% by weight.
It is important that the If the dried product is strongly dried until the water content is less than 3% by weight, the dried product itself will become too hard and it will be difficult to use it as is for consumption. Furthermore, if the material is dried to a moisture content of more than 25% by weight, it will still have stickiness that sticks to each other, which is undesirable. Even if the moisture content is as specified above, the moisture content will vary slightly depending on the moisture content, but if left for a long time, even if it is almost completely sealed, it will become sticky and stick to each other over time. Tend. Therefore, in the present invention, it is desirable to carry out the subsequent coating treatment with a protein solution relatively quickly after the drying, usually within about 24 hours, preferably within about 5 hours. In the above-mentioned coating treatment of dried natto with a protein solution, as the protein solution, for example, egg white separated from raw eggs, commercially available egg white liquid, or commercially available egg white powder dissolved in water to an appropriate concentration can be advantageously used. In addition to these egg white solutions, for example, a solution prepared by appropriately dissolving a suitable protein such as commercially available soybean protein or commercially available sodium caseinate in water, a heated solution such as gelatin, etc. can be used in substantially the same manner. Further, seasonings such as soy sauce, pepper, mirin, chili pepper, food additives such as dextrin, guar gum, etc. may be added and dissolved in the various protein solutions as required. The amount of these additives to be blended is preferably within a range that does not impede the properties of the dry protein film formation of the present invention, usually up to an amount equivalent to the solid weight of the protein. By incorporating such additives, the resulting natto processed food can be seasoned with various flavors, and its eating properties, particularly its taste, can be further improved. The surface of dried natto can be coated with the above protein solution by various methods such as immersing the dried natto in the protein solution, applying the protein solution to the dried natto, and applying the protein solution dropwise onto the dried natto. I can do it. The amount of protein solution used is not particularly limited as long as a continuous film is formed on the surface of dried natto, but it is usually about 2 to 20 g, preferably about 5 to 10 g, per 100 g of dried natto in terms of solid content. preferable. The drying operation subsequent to the protein liquid coating is carried out by an appropriate method for drying the formed protein film, such as vacuum drying, hot air drying, etc. When this drying operation is carried out by vacuum drying, the surface of the resulting food tends to be dull, and when carried out by hot air drying, the surface of the obtained food tends to be glossy. In the method of the present invention, the coating treatment and drying treatment may be repeated multiple times in order to make the dried protein coating formed as described above a more uniform and complete continuous coating. In addition, in the method of the present invention, if necessary, subsequent to the protein solution coating and drying treatment, puffing treatment, which is usually carried out in the food processing field, can be carried out, and according to this, natto processing to produce the final product It is possible to impart a soft texture, particularly good texture, to foods. The above-mentioned puffing process can be carried out according to a conventional method, for example, using a batch-type puffing machine called a so-called Bakudan or a rotary valve-type continuous puffing machine. In this way, the natto processed food of the present invention is obtained. The obtained food, as detailed in the examples below,
It has a long shelf life, is non-hygroscopic, and has a high sulfur-containing amino acid value, and is enjoyed by many people as a snack-like food. Examples of manufacturing the natto processed food of the present invention are given below as examples. In addition, the water content in each example is determined by crushing 1 to 1.5 g of the sample appropriately in a mortar and extracting it with methanol for 30 minutes.
Measured using Metrohm's "633 Karl Fischer Automat". Example 1 60kg of carefully selected and washed soybeans are cooked in a pressure cooker at 1.2kg for 20
Steamed soybeans for about 130 kg to obtain about 130 kg of steamed soybeans. To this, a suspension of 5 g of commercially available Bacillus natto in sterilized water that had been sterilized by boiling in step 2 was added when the temperature of the steamed soybeans had dropped to 80°C, and the mixture was stirred well. . Divide this into 100g portions
It was placed in a room at 40°C and kept for 10 hours. When the product temperature reached 50℃, the temperature of the room was cooled by introducing regulated air at 30℃. After 5 hours, the resulting natto was stored in the refrigerator. The analysis value of this natto is 16.6g of protein and fat.
10.0g, carbohydrates 10.2g, fiber 2.2g, ash 2.4g, and moisture 58.6g (content per 100g). In addition, the content of sulfur-containing amino acids in the protein is methionine 13
% by weight, cysteine 18% by weight and tryptophan
It was 13% by weight, and its protein value was 59. This natto was used in all subsequent examples. Put 200g of natto in a vacuum dryer and set the shelf temperature to 90℃.
It was dried for 5 hours at a vacuum level of 15 torr. The weight of natto at this time was 100 g, and the moisture content was 16%.
Next, soak the whole amount in a mixture of 30g of egg white liquid separated from raw eggs and 3g of soybean oil, mix well,
Vacuum drying was performed again for 2 hours. Furthermore, this was mixed with 30 g of egg white liquid and 3 g of soybean oil, dried for 3 hours, and then further immersed in 30 g of egg white liquid and dried for 3 hours to obtain 102 g of the natto processed food of the present invention. The moisture content of this material was 15%. The protein content of the obtained product was 40.6g (content per 100g), of which methionine was 18% by weight, cysteine was 22% by weight, and trictophane was 40.6g (content per 100g).
It was 14% by weight, and the protein value was improved to 82. Table 1 shows the results of measuring the water activity value of the obtained product using an AW meter AW-351 manufactured by Tokyo Shibaura Electric Co., Ltd. Furthermore, the obtained products were left under sealed conditions at 30℃ and 50℃, and under conditions of relative humidity 100% RH, respectively, to test the storage stability, and there was no change in either case for one month under 80℃ conditions. was also not recognized.
Further, under the condition of 50°C, no change was observed for 14 days, and although there were some cases where the appearance became slightly darkened after one month, no change was observed in non-hygroscopicity, flavor, etc. immediately after production. Furthermore, the natto odor of all the products was greatly reduced during and after the test, and no ammonia odor due to excessive fermentation of soybeans was observed. Example 2 200g of natto was placed in a hot air dryer and dried with hot air at 85°C for 2 hours and 30 minutes. The weight of natto at this time is 97.2
g, and the water content was 13.5%. After thoroughly mixing this whole amount with a liquid mixture of 3 g of commercially available egg white powder, 3 g of water, and 3 g of soybean oil, hot air drying was performed again for 30 minutes. Next, the egg white mixture was mixed with 0.5 g of black pepper, stirred well, and dried with hot air for 1 hour to obtain 95.8 g of the natto processed food of the present invention. The moisture content of this material was 11%. The physical properties of the obtained product were almost the same as those obtained in Example 1. In addition, the water activity value and storage stability of the product were measured in the same manner as in Example 1, and the results are shown in Tables 1 and 2. Example 3 500g of natto was placed in a hot air dryer and dried with hot air at 85°C for 3 hours. The weight of the natto at this time was 242 g, and the moisture content was 13%. This whole amount was mixed with a mixture of 9 g of commercially available egg white powder, 9 g of water, and 7.5 g of soybean oil, and vacuum-dried for 2 hours at a shelf temperature of 85° C. and a vacuum level of 15 torr. Furthermore, after mixing with an egg white mixture having the same composition, vacuum drying was performed again under the same conditions for 3 hours to obtain 239 g of the natto processed food of the present invention.
The moisture content of this material was 10.5%. In addition, the obtained product had approximately the same sulfur-containing amino acid content as that obtained in Example 1, and had a well-balanced high nutritional value, long-term shelf life, non-hygroscopicity,
It had flavor etc. The water activity value of this product was measured by the same test as in Example 1, and the results are shown in Table 1. Example 4 200.1g of natto was heated in a Tabai high-temp oven (HIGH-TEMP OVEN HPS-222) at a certain temperature.
It was dried at 85° C. for 4 hours to obtain 99.9 g of dried natto.
The moisture content at this time was 11.1%. This was processed at a temperature of 125°C using a No. 1 buttu slicing machine made by Koyo Kikai Seisakusho.
Puffing was carried out at a pressure of 2 atm for a processing time of 4 minutes to obtain 95.3 g of puffed natto. The moisture content of this product was 6%. Next, add 3g of egg white powder to 3g of this.
Soak it in a mixture of water and 3g of soybean oil, stir well, and heat it in the oven mentioned above.
It was dried at ℃ for 20 minutes and this operation was repeated again. Next, a solution prepared by dissolving 3 g of egg white powder in 6 g of water was applied, and the product was dried in the above oven for 40 minutes to obtain 102.7 g of the product of the present invention. Although this product has a low moisture content of 5%,
The texture was light and easy to chew.
The appearance maintained the original size of the soybeans, and there was no shrinkage due to drying. Other physical properties were almost the same as those of Examples 1-3. The water activity value test results are shown in Table 1. Example 5 364.1g of natto was dried in a ventilation dryer at an air temperature of 85℃.
After drying for hours, 209 g of dried natto was obtained. The moisture content of this material was 25.0%. This was treated with the same puff operation as in Example 4 at a temperature of 150°C and a pressure of 2 atm.
191g of puffed natto was obtained. This water content was 15%. Add to this 20.2g of water, 4.6g of sodium caseinate,
A solution prepared by adding 9.2 g of soybean oil and 1 g of granulated sugar was applied uniformly and dried in a ventilation dryer for 2 hours to obtain 179.8 g of the natto processed food of the present invention. The moisture content of this material was 5.7%. Even if this product was left in a 50°C heating room for a week, it did not become sticky or the grains would stick together.
Also, when the grains were left at 30°C and 100% humidity for a week, they became slightly soft due to moisture absorption, but the grains did not stick together. No abnormalities were observed after eating any of them. The water activity values were determined in the same manner as in Example 1, and the results are shown in Table 1. Example 6 193.4 g of natto was dried in a ventilation dryer at 85° C. for 3 hours to obtain 101.3 g of dried natto. This was puffed in the same manner as in Examples 4 and 5 to obtain 95.2 g of puffed natto. 35.2 g of a solution containing soybean protein, water, and soybean oil in a ratio of 1:9:2 was thoroughly applied to the surface, and ventilation drying was performed for 1 hour and 20 minutes to obtain 95.4 g of a processed natto product of the present invention. The moisture content was 6%. This product had properties comparable to those obtained in Example 5. The water activity values were determined in the same manner as in Example 1, and the results are shown in Table 1 below. For comparison, Tables 1 and 2 show Example 2 except that the coating treatment with the egg white liquid of the present invention was not performed.
The test results for natto obtained in the same manner as above are also listed as a control product.
【表】【table】
【表】
尚表中※印は、供試試料が強い臭いを発生する
ことを示す。また※※印は、強い臭いを発生する
と共に製品がやや黒ずんだ色を呈することを示
す。
また上記第２表に示した各試料の経時変化（所
定時間保存後のべとつき）を次の通り観察した。
即ち各試料の所定量を適当な大きさのトレイの短
軸方向の一部分に静置し、該トレイの試料静置部
分を上にして一定角度に傾斜させ、これにより試
料が下方へ落ちるか否かを観察した。以下の試料
を用いた結果を参考図Ａ，Ｂ及びＣとして示す。
試料No. 結 果
本発明品 参考図Ａ
（30℃、密封、30日放置後）
本発明品 参考図Ｂ
（50℃、湿度100％R.H.30日放置後）
対照品 参考図Ｃ
（30℃、密封、１日放置後）
各参考図より明らかな通り、本発明品は、良好
な放置安定性を有し、30日経過後も、製造当初の
べとつきのない品質を保持しているのに対し、対
照品は１日経過後、既に各納豆粒子が相互にくつ
つき合い、放置安定性に劣ることが明らかであ
る。[Table] The * mark in the table indicates that the test sample generates a strong odor. In addition, the ※※ mark indicates that the product emits a strong odor and has a slightly dark color. In addition, changes over time (stickiness after storage for a predetermined time) of each sample shown in Table 2 above were observed as follows.
In other words, a predetermined amount of each sample is placed on a portion of a tray of an appropriate size in the short axis direction, and the tray is tilted at a certain angle with the portion on which the sample is placed upward, thereby determining whether or not the sample will fall downward. I observed that. The results using the following samples are shown as Reference Figures A, B, and C. Sample No. Results Invention product Reference diagram A (30℃, sealed, after being left for 30 days) Invention product Reference diagram B (50℃, humidity 100%RH after being left for 30 days) Control product Reference diagram C (30℃, sealed , after being left for 1 day) As is clear from each reference figure, the product of the present invention has good storage stability and maintains the non-sticky quality at the time of manufacture even after 30 days, whereas the control After one day, the natto particles were already sticking to each other, and it was clear that the product had poor storage stability.