レダクトンに関する研究-10-馬鈴薯の煮沸に伴うインドフェノール還元値の増加について-1-
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概要
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The indophenol reducing value increases during the boiling procedure of potato homogenate or of its centrifuged supernatant in a diluted acid medium. This phenomenon has been explained as the formation of free L-ascorbic acid (ASA) resulted by the heat degradation of the bound form of ASA (i.e. likely ascorbigen) in potato. A series of experiments were carried out to elucidate the mechanism of this phenomenon, and several results were obtained as follows: (1) There was a marked rise of indophenol reducing value of boiled potato homogenate of its centrifuged supernatant, when vitamin C was assayed by the method of indophenol-xylene. On the other hand, when the method of 2, 4-dinitrophenylhydrazine (2, 4-DNP) was used for the assay of vitamin C, a small amounts of ASA was only found and decreased during the boiling procedure, and the amounts of dehydro-L-ascorbic acid (DHA) and 2, 3-diketo-L-gulonic acid (DKG) were predominant in potato homogenate and subseqently disappeared quickly during the boiling process. (2) Aci-reductone B (2, 3, 4-trihydroxy-2-pentenoic acid) and aci-reductone III (5-methyl-3, 4-dihydroxy tetron) were detected in the boiled potato homogenate by the method of thin-layer chromatography. The contents of these two compounds increased during the boiling process of potato. (3) When each of the standard ASA and DHA in 2% metaphosphoric acid aqueous solution* was boiled, only the indophenol reducing value of the latter was markedly increased. These results indicate that the increase of indophenol reducing value of boiled potato is not due to the bound ASA, and that the formation of reductones by the heat degradation of DHA contributes to the increase of indophenol reducing value of boiled potato. * These concentrations were both in rough accord with that of potato homogenate.
- 公益社団法人 日本農芸化学会の論文