Influence of different milk-clotting enzymes on the quality and shelf life of semihard cheeses

The study examined semi-hard cheeses made with milk-clotting enzymes (MCEs) of animal origin (Naturen Extra with a mass fraction of chymosin 95%, “Bovine Pepsin” with a mass fraction of chymosin 10%), microbial origin (Fromase 750 XLG) and recombinant origin (Chy-max Extra and Chy-max Supreme), at an introduction dose of MCE of 1,500 to 6,000 IMCU per 100 kg of milk. In cheeses at the age of 7, 60, and 150 days, pH, the degree of proteolysis, the content of peptides with a mass of 1–5 kDa, and the compressive stress at fracture were determined. Cheeses produced with a dose of MCE of 5,000–6,000 IMCU/100 kg of milk had a substantially (p<0.05) lower pH compared to cheeses made with doses of MCEs of 1,500–3,000 IMCU/100 kg of milk. At the same time points, there were no significant differences (p>0.05) in the degree of proteolysis between cheeses made using diverse types of MCEs at the same dose. The exceptions were cheeses produced with Chy-max Supreme, which had a substantially (p<0.05) lower level of proteolysis. Sensory assessment of the bitter taste intensity in cheeses is proportional to the content of peptides with a molecular weight of 1–5 kDa. With an increase in the MCE dose, the content of peptides with a molecular weight of 1 to 5 kDa increases in cheese. Chy-max Supreme forms the least number of bitter peptides in cheeses (p<0.05). There are no significant differences (p<0.05) in the magnitude of the compressive stress at fracture between the cheese variants produced with the same MCE doses of diverse types at the same time points.