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A modified indophenol‐xylene extraction method for the determination of ascorbic acid in soybeans
Author(s) -
Weakley F. B.,
McKinney L. L.
Publication year - 1958
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02640112
Subject(s) - ascorbic acid , indophenol , chemistry , extraction (chemistry) , chromatography , germination , vitamin , vitamin c , reagent , food science , biochemistry , botany , biology , organic chemistry
Summary The indophenol‐xylene extraction method used to estimate ascorbic acid was modified to eliminate appreciable sulfhydryl interference encountered when extracts of soybeans are assayed for this vitamin. The sulfhydryl interference was eliminated by means of p ‐chloromercuribenzoic acid ( p ‐CMB). This reagent did not affect the indophenol color nor did it interfere in the estimation of true ascorbic acid. The ascorbic acid values for soybeans germinated up to four days, as determined by the modified method , were 15% to 54% lower than the values obtained by the standard procedure (15), in which sulfhydryl groups are not masked. Ungerminated soybeans assayed by the modified method contained no ascorbic acid. The vitamin appeared shortly after the start of germination and increased rapidly to 470 p.p.m. in four days. The ascorbic acid found was predominantly, if not all, in the reduced form. The ascorbic acid content of freshly harvested Kanrich green soybeans as determined by the modified method was 20–25% lower than that obtained by the nomal method. Present data indicate possible sulfhydryl interference in ascorbic acid values previously reported in soybean germination studies that employed indophenol methods of assay. Paper chromatography was used to establish the presence of ascorbic acid and sulfhydryl groups in acid extracts of the germinated soybeans.