Effects of catalyst and duration of digestion on the analytical values of crude protein by Kjeldahl method
1989
Han, I.K. | Ha, J.K. | Hyun, Y. | Choi, Y.J. (Seoul National Univ., Suwon (Korea R.). Coll. of Agriculture)
The effects of catalyst and duration of digestion on the analytical values of crude protein of various feed samples were compared by Kjeldahl method. Samples used for crude protein analysis were fish meal, soybean meal, concentrate mixture and commercial mixed feed. Crude protein of each sample was determined using Hg, Cu or Se as catalyst and the duration of digestion was 20, 40, 60 and 80 min. The followings are the results of experiments conducted at Seoul National University (SNU) and Purina Korea Inc. (PKI). The results obtained by SNU indicated that average crude protein content of four samples determined with Hg catalyst was highest, followed by those analyzed with Cu and Se catalyst without any significant difference between the last two. Protein value increased with increased duration of digestion. However, no significant differences were found between 40 and 60min digestion. The results obtained by SNU tended to be higher than those at PKI. The results of protein analysis by PKI using a Kjeltec autosystem were higher than those of Kjeldahl method. It was also found that Hg was the most effective catalyst in the results obtained from PKI. The effect of duration of digestion on analytical values of protein obtained by PKI showed the same trend observed in the results of SNU. When the effect of catalyst was analyzed for each feed sample Hg was more effective than Se or Cu for fish meal, soybean meal and concentrate mixture, but no differences in protein values of a commercial feed was found among different catalysts
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