Cereal Chem. 70:27-28   |  VIEW ARTICLE

Rapid Solid-Phase Determination of Cereal Protein Using Bicinchoninic Acid.

K.-Y. Chan and B. P. Wasserman. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

A modification of the bicinchoninic acid assay that can be used for the rapid determination of protein in cereal-based materials is described. Samples are directly suspended in bicinchoninic acid reagent, where under sonication the protein undergoes reaction and a soluble purple chromophore is released. After a clarification step, absorbance readings are obtained and protein quantified by comparison with a standard curve. In the various corn-derived fractions tested, the solid-phase assay was linear with the amount of sample added, and high reproducibility was observed between replicates. With two commercially prepared flours (Micro-Crisp and Pure n Thick), direct comparisons with the Kjeldahl assay showed general agreement. In two other samples (corn meal and zein), higher readings, possibly derived from the contribution of nonprotein nitrogen, were obtained by the Kjeldahl method. The solid-phase assay represents a rapid alternative to the Kjeldahl assay, especially when numerous insoluble proteinaceous materials require screening.