酵素ポリフェノールオキシダーゼによる酸化および空気酸化の二つの方法でクロロゲン酸とL-フェニルアラニンの混合液から緑色溶液を調製し,セファデックス・G-25で色素の分別を行なった。その結果,両緑色溶液は,褐色,緑色,青紫色の三成分に分画された。このうち,緑色および青紫色色素を精製,粉末とし可視および赤外吸収スペクトルを測定した結果から酵素酸化,空気酸化ともに,同一機構で反応すると推定した。また,各色素の溶媒に対する溶解性およびその他二三の化学的性質から各色素はナトリウム塩を形成していると推定した。

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After heating the aqueous model solution containing carbonyl compounds and amino acids, its reactivity was investigated by gas chromatography.
1) At pH6.5, n-propionaldehyde easily reacted with L-arginine HCl, L-lysine HCl, L-histidine HCl, L-tryptophan and especially with L-cysteine. After heating, browning was found in each solution and volatile flavor of n-propionaldehyde was reduced. These amio acids reacted with n-capronaldehyde as well as n-propionaldehyde. The volatiles formed by the reaction between the carbonyls and L-cysteine were sulfurous flavor.
2) On varying the contents of L-arginine HCl, L-lysine HCl and L-histidine HCl, about a half amount of carbonyl compound in the simple model system was made nonvolatile by addition of 5 fold amino acid in molarity to carbonyl compound. In case of the mixed model system of carbonyl compounds (1mM formaldehyde-1mM acetaldehyde-1mM n-propionaldehyde-1mM n-valeraldekyde-2.5mM n-carpronaldehype), L-lysine HCl or L-histidine HCl was most effective to make nonvolatile about a half amount of carbonyl compounds in model system. Its amino acid concentration was 20 fold in molarity to carbonyl compounds. L-cysteine made entirely nonvolatile carbonyl compounds in equal molarity to carbonyls.

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Rice stored for 2 years was cooked in aqueous solution containing amino acids, and the volatile carbonyl compounds produced from cooked rice and flavor were investigated by gas chromatography and sensory test respectively.
1) L-cysteine, L-lysine HCl and L-histidine HCl were effective to make nonvolatile n-valeraldehyde and n-carpornaldehyde, which were attributed to the stale flavor (komai-shu). Of these amino acids, L-cysteine was most reactive, accompanying sulfurous flavor in cooked rice. About a half amount of carbonyl compounds (n-valeraldehyde and n-capronaldehyde) in cooked rice was made nonvolatile by adding about 300mg of L-lysine HCl or L-histidine HCl to 100g of milled rice.
2) As the result of sensory test, it was necessary to add 80-160mg% of L-lysine HCl in stored rice for elimination of the stale flavor. Flavor was more improved by the addition of the mixture of 80mg of L-lysine HCl, 20mg% of L-histidine HCl and 5mg% of L-tryptophan in stored rice. The addition of amino acids as described above might be also useful for improvement of nutritive value of rice.

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