U svijetu posljednjih godina sve više se osjeća nedostatak sirila zbog povećane proizvodnje sireva i zbog neekonomičnosti klanja teladi. Zbog toga su se tražile mogućnosti zamjene sirišnog drugim proteolitičkim fermentima iz biljaka, mikroorganizama i životinja.In this investigation the milk - clotting activity of crystalline pig pepsin was determined by using method of Soxhlet. The suitability of curd for making soft and kachkaval cheeses was examined, too. The results were: It takes a long time to coagulate milk with pepsin. First half of this time was from adding pepsin milk, to the first marks of coagulation. Second half was from the beginning of coagulation to the end of clotting (cutting time); Pepsin concentration of 0,020 g/L milk gives good coagulum, but softer than the one with rennet; For cheese - making, the practical clotting - strength of pepsin was about one half of that determined by the method of Soxhlet. The cura was suitable for cooking process which is important in making kachkaval cheese; The white soft and kachkaval cheeses made with pepsin had had good organoleptic properties without bitterness for 21 days
