Tryptone, also known as casein tryptone, pancreatic digest of casein, pancreatin hydrolyzed casein, pancreatin hydrolyzed casein, and pancreatin hydrolyzed casein. It is a light yellow to almost white dry powder made from casein through digestion, decolorization, filtration, concentration and spray drying. Easily soluble in water, with a light yellow color in the aqueous solution. Casein, also known as casein, is a highly nutritious phosphoprotein extracted from milk and is a commonly used raw material for producing peptone. The peptone produced with this raw material has a relatively complete range of amino acids, especially a high content of tryptophan. So it is most suitable for conducting indigo substrate and sugar fermentation experiments in bacterial biochemical experiments. However, it lacks sulfur-containing amino acids such as cystine and methionine, making it unsuitable for hydrogen sulfide testing.