Cereal Chem 47:288 - 295. | VIEW
Extraction and Determination of Phytic Acid in Beans (Phaseolus vulgaris).
R. U. Makower. Copyright 1970 by the American Association of Cereal Chemists, Inc.
Analyses of phytic acid by four procedures, all based on precipitation of ferric phytate, were tested on Pinto beans of different maturities and on purified phytic acid. The colorimetric determination of iron in ferric phytate, after initial conversion to ferric hydroxide, has the advantage of greater speed, convenience, and improved separation from interfering substances over the determinations of iron or phosphate in ashed ferric phytate. The indirect determination of iron in the precipitate, by measuring residual iron in solution, was unsatisfactory for analyzing small amounts of phytic acid present in immature beans; only the direct methods gave meaningful results. All four procedures yielded comparable results with mature beans of appreciable phytic acid content. Better extraction of phytic acid from immature beans was obtained with hydrochloric acid than with perchloric or with trichloroacetic acid. Techniques, precautions, and sources of error in extraction are discussed.