All amino acids contain an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The amine group nitrogen contains one nitrogen molecule. The side chains of most amino-acids are only made up of carbon, oxygen and hydrogen, although some amino acids (including lysine, tryptophan, histidine and arginine) contain additional nitrogen molecules. If large amounts of these high nitrogen-containing amino acids are found in protein foods, the amount of nitrogen analysed would be greater than in proteins where lower amounts of the high nitrogen-containing amino acids are found. In cuts, such as the hind shin, significant amounts of collagen and elastin are found, compared to ‘‘clean’’ muscle cuts such as the topside