Comparison of procedures to determine protein content of developing bean seeds (Phaseolus vulgaris)

Micro-Kjeldahl, Lowry and Bradford procedures were compared for determining the protein content of Phaseolus vulgaris seeds during their development. Micro-Kjeldahl and biuret techniques were also compared with mature seeds of a normal and a genetically-improved bean cultivar. The protein contents of casein and soy protein isolate were as well estimated by these four methods. For many samples of both bean and food protein products large disagreements were found between micro-Kjeldahl and the other three procedures.