Abstract: Macromolecule protein in protein hydrolysate was deposited by using 10% trichloroacetic acid. After centrifugal-ization and filtration, biuret reagent was added to the clear solution. The OD value was mensurated under 540nm. Then thecontent of peptides of the sample was obtained through contrasted on the standard curve of Gly-Gly-Tyr-Arg tetrapeptide.

Key words: biuret reaction, trichloroacetic acid, content of peptides