Hydrolysis of casein: a comparative study of two proteases and their peptide maps

Gel electrophoresis (SDS‐PAGE) and reversed phase‐high performance liquid chromatography (RP‐HPLC) techniques were used to illustrate the actions of two enzymes, a pineapple stem bromelain and a Bacillus protease (Bacillus subtilis), on bovine caseins. the aim of the study was to ascertain the possible future application of the enzymes in the production of bitter peptides. The results illustrate that the individual actions of the two proteases produce hydrolysates of very different peptide composition. the Bacillus protease action on casein results in the production of a greater variety of hydrophobic, low molecular weight (<10 kDa) peptides, due to a more extensive proteinase activity. Bromelain action however results in a hydrophobic hydrolysate containing a greater number of high molecular weight peptides (>10 kDa), which are not normally associated with flavour fractions. The results of the study, show that the hydrolysate produced by the Bacillus protease action on casein, is a greater potential source of bitter peptides for future study, than the hydrolysate produced by bromelain.