The Lysine, Methionine and Threonine Content of Meats

Abstract

Leuconostoc mesenteroides was used for the determination of lysine and methionine in meats. Streptococcus faecalis was used for similar determinations of methionine and threonine. The analyses were made on acid hydrolysates of the crude homogeneous meat samples. The average threonine content of 24 different skeletal muscle tissues was 4.4% of the crude protein, while the lysine content was 8.1% and the methionine content was 2.3%. A statistical analysis indicated that no significant differences existed between the results obtained for the muscle tissue proteins, but that beef brain, kidney and tongue were significantly lower in methionine while beef brain, kidney and liver were significantly lower in lysine. Studies on retention show that these amino acids are not lost or destroyed in meats during the cooking process.