EN
The enzymatic hydrolysis of casein was investigated by a simple in vitro test method. The hydrolysis was carried out in two stages, one in the acidic (pepsin) and the other in the alkaline (trypsin) medium. The concentration of alpha-amine nitrogen was determined in the incubation medium using the colorimetric method. NO3- content in the buffer ranged between 150 and 2000 mg/dm3, whereas NO3- concentration was from 6,25 to 50 mg/dm3. The process of protein digestion was shown to be inhibited 13- 15% in the presence of NO3- and 7- 12% in the presence of NO2- as compared to the control samples.