[Colorimetric determination of tryptophan in foods]

A modification of the method of Spies and Chambers for the determination of tryptophan in food products is described. The results were compared with those obtained with the microbiological method and gave identical results. The results on tryptophan content of bean broth were consistently higher than expected. Apparently, bean broth contains certain factors, which interfere with both procedures. In summary, the modified method is simple and easy to perform in large numbers of samples.