Nitrogen-to-protein conversion factors for common vegetables in Japan

Twenty (JAPANESE) vegetables in Japan were analyzed for total nitrogen, amino acid nitrogen, amide nitrogen, and nonprotein nitrogen and then calculated nitrogen-to-protein conversion factors were calculated. The average conversion factor based on quantitative amino acid composition data was 6.00. However, the use of this concentrations, due to the presence of high levels of nonprotein nitrogen. The distribution of protein nitrogen to factor for estimating protein content led to a considerable difference from estimates based oil amino acid residue total nitrogen averaged 73%. Adjusted conversion factors, defined as the proportion of amino acid nitrogen to total nitrogen, averaged 4.39. Protein contents estimated with this factor agreed well with contents determined by amino acid residues.