Studies on the lysine-rich food : I. Loss of lysine, and browning and its prevention

In order to heighten the nutritional value of food, the lysine-rich food has been made. However, added lysine reacts on sugar in food and results in loss of lysine, browning of food arid further bitterness. The condition which causes the loss of lysine and the browning has been examined and the method for preventing it has been studied. 1. Most of amino acids react on sugar and result in the browning, especially in case of addition of lysine it is remarkable. It has been considered that this is due to the fact that lysine has a reactive e-amino group. The conditions of lysine-sugar reaction were as follows: a) Effect of the kind of sugar: Pentose reacted most strongly on lysine and hexose and disaccharide followed. b) Effect of the concentration of sugar: As the concentration of sugar increased, the browning became stronger. c) Effect of pH: The loss of lysine and the browning were weak in acidic solution, but strong in alkaline. d) Effect of buffer solution: According to the kind of buffer solution used and its concentration, the loss of lysine was different. In phosphate buffer solution, the reaction was accelerated but in Tris buffer solution, it was not. e) Effect of heat treatment : In heating up to 100℃, the loss of lysine was not so strong, but over 100℃ became strong. f) Effect of other kinds of amino acids: Cystine, glutamic acid and histidine inhibited the lysine-sugar reaction, but tryptophan and tyrosine accelerated it. g) Effect of metal : In the existence of Fe^+++ion, the reaction was accelerated, but Ca^++ and Mg^++ion inhibited the reaction. 2. Lysine reacted strongly on not only sugar, but also aldehyde which produced when treating food and resulted in the browning. 3. In order to prevent the loss of lysine and the browning, several surfactants which seemed to give any effect on the amino group of lysine were added to the solution of lysine and sugar, which, afterwards, were heated, but the loss of lysine could not be prevented. 4. The decrease of lysine and the browning on the liquid food added lysine were examined. Adding lysine to fermented milk or orange juice and stored at 5℃, the browning has hardly caused, but at 30℃ for more than one month, the decrease of lysine and the browning of liquid have been observed. 5. On the lysine-rich bread made by the usual method which lysine was added to dough with water, 20 to 30 per cent of lysine added was lost and adding 0.3 per cent of lysine to bread, the browning caused up to such a grade that it could not be sold in market. Therefore, the manufacturing method for lysine-rich bread which does not cause the browning has been studied. So far, lysine was dissolved in water and then it was added to dough, however, adding lysine to dough after having suspended it in shortening oil, little browning has been observed. Further, adding it to dough after having coated lysine with hard oil, the browning has been prevented. 6. The manufacturing method for lysine-rich food adding ε-N-acetyl-L-lysine instead of lysine has been found, and the browning has been perfectly prevented by this method.1. 食品の栄養価値向上のためリジン強化食品の製造が試みられているが,添加されるリジンが食品中に合まれる糖などと反応して褐変化をおこし,時にはニガ味を生じ,また添加されたリジンが損失するので,これの製造を困難にしている.このリジンの減少と褐変化の条件を検討し,さらにこれの防止法について研究した. 2. ほとんどのアミノ酸は糖と反応して褐変化をおこすが,特にリジンにおいて著しい.これはリジンがα-アミノ基のほかに反応性に富むε-アミノ基を持つためと考えられる.リジンと糖の反応の状態は次のようであつた.糖の種類との関係: 5炭糖が最も強くリジンと反応し,次に6炭糖,2炭糖の順であつた.糖の濃度: 糖の濃度が濃くなるほど着色は強くなつた(1～10M相当量).またリジンの減少もそれに従つた.pHとの関係 : クエン酸系緩衝液(pH1.8～5.0)ではリジンの減少はみられるが,全く着色せず,リン酸緩衝液(pH3.8～8.6)ではアルカリ性になるほど着色が強くなり,リジンの減少度もそれに比例していた.酸性とアルカリ性でおこるリジン-糖反応は異なる機構によるものと考えた.緩衝液による影響: 使用した緩衝液の種類および濃度によつてリジン減少度および着色度が異つた.リン酸系,クエン酸系は反応を促進し,トリス系では反応が弱かつた.加熱条件との関係: 100℃までの加熱では着色はそれ程強くないが,これを越すと急に強く着色し,リジンも減少した.共存する他のアミノ酸との関係: リジンーグルコース系にトリプトフアン,セリン,チロシン,が共存すると反応は促進され,シスチン,グルタミン酸が共存すると抑制された.金属イオンとの関係: Fe^+++イオンの共存は反応を促進し,Ca^++ Mg^++イオンは反応を抑制した. 3. リジンは糖ばかりでなく,食品加工中に発生すると考えられるアセトアルデヒド,フルフラールなどのカルボニール化合物と強く反応して,褐変化がおこつた.それは酸性で弱くアルカリ性で強かつた. 4. リジンの損失と褐変化を防ぐ目的で,リジンのアミノ基に何らかの影響をおよぼすと考えられるポリリン酸塩,陰イオン性界面活性剤をリジンと一緒に加えることを試みたが,着色防止の効果はみられなかつた. 5. 乳酸発酵飲料およびオレンヂジュースなどの酸性飲料にリジンを加えて5℃に保存すると着色はおこらないが,室温(30℃)に1ヶ月以上おくとリジンの減少および液の着色がみられた. 6. 従来のリジン強化パンの製造法によると,添加されたリジンの20～30％は損失し,リジンを0.3％以上加えると市販出来ない位に着色することがわかつた.そこで着色しないリジン強化パンの製造法について研究した.従来法ではリジン塩酸塩を仕込水にとかしてからパン生地に加えていたが,これを改良しリジンを前もつて生地に加えるショートニングオイルに懸濁してから加えると着色が少なく,パンの他の性質も良好であつた.またリジン塩酸塩を固形油脂などでコーティングしてからパン生地に加えると着色がより少なかつた.またリジンのε-アミノ基誘導体であるε-N-acetyl-L-lysineを添加するリジン強化食品の製造法を見出した

リジン強化食品の製造に関する研究 : I. 添加リジンの損失と食品の着色およびその防止法

In order to heighten the nutritional value of food, the lysine-rich food has been made. However, added lysine reacts on sugar in food and results in loss of lysine, browning of food arid further bitterness. The condition which causes the loss of lysine and the browning has been examined and the method for preventing it has been studied. 1. Most of amino acids react on sugar and result in the browning, especially in case of addition of lysine it is remarkable. It has been considered that this is due to the fact that lysine has a reactive e-amino group. The conditions of lysine-sugar reaction were as follows: a) Effect of the kind of sugar: Pentose reacted most strongly on lysine and hexose and disaccharide followed. b) Effect of the concentration of sugar: As the concentration of sugar increased, the browning became stronger. c) Effect of pH: The loss of lysine and the browning were weak in acidic solution, but strong in alkaline. d) Effect of buffer solution: According to the kind of buffer solution used and its concentration, the loss of lysine was different. In phosphate buffer solution, the reaction was accelerated but in Tris buffer solution, it was not. e) Effect of heat treatment : In heating up to 100℃, the loss of lysine was not so strong, but over 100℃ became strong. f) Effect of other kinds of amino acids: Cystine, glutamic acid and histidine inhibited the lysine-sugar reaction, but tryptophan and tyrosine accelerated it. g) Effect of metal : In the existence of Fe^+++ion, the reaction was accelerated, but Ca^++ and Mg^++ion inhibited the reaction. 2. Lysine reacted strongly on not only sugar, but also aldehyde which produced when treating food and resulted in the browning. 3. In order to prevent the loss of lysine and the browning, several surfactants which seemed to give any effect on the amino group of lysine were added to the solution of lysine and sugar, which, afterwards, were heated, but the loss of lysine could not be prevented. 4. The decrease of lysine and the browning on the liquid food added lysine were examined. Adding lysine to fermented milk or orange juice and stored at 5℃, the browning has hardly caused, but at 30℃ for more than one month, the decrease of lysine and the browning of liquid have been observed. 5. On the lysine-rich bread made by the usual method which lysine was added to dough with water, 20 to 30 per cent of lysine added was lost and adding 0.3 per cent of lysine to bread, the browning caused up to such a grade that it could not be sold in market. Therefore, the manufacturing method for lysine-rich bread which does not cause the browning has been studied. So far, lysine was dissolved in water and then it was added to dough, however, adding lysine to dough after having suspended it in shortening oil, little browning has been observed. Further, adding it to dough after having coated lysine with hard oil, the browning has been prevented. 6. The manufacturing method for lysine-rich food adding ε-N-acetyl-L-lysine instead of lysine has been found, and the browning has been perfectly prevented by this method.1. 食品の栄養価値向上のためリジン強化食品の製造が試みられているが,添加されるリジンが食品中に合まれる糖などと反応して褐変化をおこし,時にはニガ味を生じ,また添加されたリジンが損失するので,これの製造を困難にしている.このリジンの減少と褐変化の条件を検討し,さらにこれの防止法について研究した. 2. ほとんどのアミノ酸は糖と反応して褐変化をおこすが,特にリジンにおいて著しい.これはリジンがα-アミノ基のほかに反応性に富むε-アミノ基を持つためと考えられる.リジンと糖の反応の状態は次のようであつた.糖の種類との関係: 5炭糖が最も強くリジンと反応し,次に6炭糖,2炭糖の順であつた.糖の濃度: 糖の濃度が濃くなるほど着色は強くなつた(1～10M相当量).またリジンの減少もそれに従つた.pHとの関係 : クエン酸系緩衝液(pH1.8～5.0)ではリジンの減少はみられるが,全く着色せず,リン酸緩衝液(pH3.8～8.6)ではアルカリ性になるほど着色が強くなり,リジンの減少度もそれに比例していた.酸性とアルカリ性でおこるリジン-糖反応は異なる機構によるものと考えた.緩衝液による影響: 使用した緩衝液の種類および濃度によつてリジン減少度および着色度が異つた.リン酸系,クエン酸系は反応を促進し,トリス系では反応が弱かつた.加熱条件との関係: 100℃までの加熱では着色はそれ程強くないが,これを越すと急に強く着色し,リジンも減少した.共存する他のアミノ酸との関係: リジンーグルコース系にトリプトフアン,セリン,チロシン,が共存すると反応は促進され,シスチン,グルタミン酸が共存すると抑制された.金属イオンとの関係: Fe^+++イオンの共存は反応を促進し,Ca^++ Mg^++イオンは反応を抑制した. 3. リジンは糖ばかりでなく,食品加工中に発生すると考えられるアセトアルデヒド,フルフラールなどのカルボニール化合物と強く反応して,褐変化がおこつた.それは酸性で弱くアルカリ性で強かつた. 4. リジンの損失と褐変化を防ぐ目的で,リジンのアミノ基に何らかの影響をおよぼすと考えられるポリリン酸塩,陰イオン性界面活性剤をリジンと一緒に加えることを試みたが,着色防止の効果はみられなかつた. 5. 乳酸発酵飲料およびオレンヂジュースなどの酸性飲料にリジンを加えて5℃に保存すると着色はおこらないが,室温(30℃)に1ヶ月以上おくとリジンの減少および液の着色がみられた. 6. 従来のリジン強化パンの製造法によると,添加されたリジンの20～30％は損失し,リジンを0.3％以上加えると市販出来ない位に着色することがわかつた.そこで着色しないリジン強化パンの製造法について研究した.従来法ではリジン塩酸塩を仕込水にとかしてからパン生地に加えていたが,これを改良しリジンを前もつて生地に加えるショートニングオイルに懸濁してから加えると着色が少なく,パンの他の性質も良好であつた.またリジン塩酸塩を固形油脂などでコーティングしてからパン生地に加えると着色がより少なかつた.またリジンのε-アミノ基誘導体であるε-N-acetyl-L-lysineを添加するリジン強化食品の製造法を見出した