The aim of this work was to study the influence of milk‐clotting enzymes on whey starter culture and hard cheesemaking. Four cheeses were prepared simultaneously per cheesemaking day, and the experiment repeated on eight consecutive days. Adult bovine rennet was used in the control cheeses, and three formulations of fermentation‐produced chymosin (FPC) in the experimental cheeses. Whey cultures were obtained from the whey of the preceding cheeses, incubated individually for 24 h at 42°C. pH values of the control and experimental whey did not differ significantly before incubation, but after 24 h incubation the pH of the FPC whey was significantly higher than that of the control. Soluble nitrogen content in trichloroacetic acid 2% and 12% and in phosphotungstic acid 2.5% was significantly lower for all experimental whey samples than for control whey. This probably explains the decrease in the acidification rate of the whey cultures when bovine coagulant is replaced by FPC in hard cheesemaking.