The determination of hydroxyproline in meat products is an often used parameter for the evaluation of meat quality. Hydroxyproline is a part of collagen and occurs therefore only in sinews, bones, gristle and skin. A high amount of hydroxyproline is an indication that raw material with cheap quality was used. The samples require acid hydrolyzation to set the hydroxyproline free from the connective tissue and separated from fat. With chloramine T the hydroxyproline will be oxidized to pyrrol. This compound will be converted to a colored product with 4-dimethylaminobenzaldehyde and afterwards determined with a photometer at 558 nm.