The objective of the present study was to develop methods for the identification of β-casein and the components of its hydrolysate released by plasmin, on the basis of the second derivatives of UV spectra and the parameters describing them. These parameters characterise the location of the most common extrema of derivatives of UV spectra in proteins. β-Casein was hydrolysed by plasmin. The products obtained were isolated and separated by ultrafiltration and reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with a photodiode detection system. In our experiment this detection method was used for a qualitative analysis of β-casein and components of its hydrolysate on the basis of parameters characterising UV spectra. The results obtained indicate the suitability of RP-HPLC and analysis of the second derivatives of UV spectra for the identification of proteins and peptides showing different concentrations of tyrosine and other aromatic amino acids.