Stability
and recovery of Trp is poor in conditions where acid and oxygen
are present as well as acid hydrolysis due to the indole group of
Trp. Sodium hydroxide is the most effective alkaline used for protein
hydrolysis with or without a carbohydrate or thiodiglycol as
an antioxidant. Trp has often being ignored in the assessment of
overall amino acid profile of foods because, Trp exhibits a strong
native fluorescence, and fluorometric method has been widely
used to determine Trp content without derivatization