Evaluation of the Biuret and Dye‐Binding Methods for Protein Determination in Meats

SUMMARY The biuret method of protein estimation was compared with the Kjeldahl method. Highly significant positive correlations with Kjeldahl protein of 0.99, 0.99, 0.98, and 0.99 were obtained for ground beef, pork, chicken breast, and cod, respectively. The high correlations between the two methods and the small standard deviations for the biuret values point out the reliability and the accuracy of the biuret method. The same substances were analyzed by the Orange G dye‐binding method with highly significant positive correlations with Kjeldahl protein of 0.90, 0.80, 0.94, and 0.95 for ground beef, pork, chicken breast, and cod, respectively. However, the amount of dye bound per g protein varies with the protein content of the sample, and the precision is poor. Orange G dye binding has possibilities for use in analyzing meat proteins only if the preparations and procedures are carefully standardized and the protein content does not vary more than a few percent. With Amido Black 10B, the amount of dye bound was too strongly dependent upon sample size to justify further investigation of this dye for estimation of the protein content of comminuted meats.