Thermal Inactivation of Residual Milk Clotting Enzymes in Whey

Melt and rheological properties of Mozzarella cheese as affected by starter culture and coagulating enzymes

“…These differences in observations may be because the combined effect of the starter culture and the coagulating enzyme may not have been considered or because some of the enzyme may have been inactivated during cooking and stretching in our study. As described earlier, CP protease is more heat sensitive than chymosin [40]. Various researchers have reported that the coagulant is responsible for the formation of large peptides, while smaller peptides and free amino acids are produced by starter bacteria, possibly from peptides initially produced by the coagulant [33].…”

Effect of cook temperature on primary proteolysis and predicted residual chymosin activity of a semi-hard cheese manufactured using thermophilic cultures

“…Increased rates of acidification and decreased curd pH increase the thermal stability of milk-clotting enzymes (Fox, 1969;Garnot & Molle´, 1987;Thunell, Deursch, & Ernstrom, 1979) and their retention in curd (Holmes et al, 1977;Lawrence, Heap, & Gilles, 1984) and thus increase the residual enzyme activity. Curd pH values during cooking did not differ significantly between cook tempera- Table 4 Predicted residual chymosin activities, obtained using the temperature and pH profiles monitored during cheesemaking and the model of Hayes, Oliveira, McSweeney, and Kelly (2002) (Eq. (1)), in experimental cheeses cooked to different temperatures, at the end of cooking a , and at the end of the stir out b period tures in this study; however, the rate of acidification was faster during stir-out in the cheeses cooked to lower temperatures (Sheehan et al, 2006).…”

Effect of pH and Calcium Concentration on Proteolysis in Mozzarella Cheese

“…The higher level of proteolysis in the DA1 cheese, compared with the DA2 and DA3 cheeses, may be attributed to a number of factors: (1) the higher content of moisture-in-nonfat substance, which favors proteolysis (Creamer, 1971); (2) increased susceptibility of casein to proteolysis by residual rennet due to the lower calcium content while the curd is in contact with the whey and during subsequent storage (Fox, 1970;O'Keeffe et al, 1975); and (3) an expected greater retention of rennet in the cheese due to the lower pH at setting and at whey drainage (Creamer et al, 1985). The higher level of proteolysis in the CL cheese compared to DA2, despite the similar value for pH at setting and at draining, may be related to its lower final pH, which should increase the stability of retained rennet (Thunell et al, 1979) and proteolysis by rennet (Tam and Whitaker, 1972;Fox, 1977, 1980). The greater proteolysis in the CL cheese compared to DA3 may be due to its slightly lower pH and to the use of a starter culture, which makes a relatively small (compared to chymosin) but significant contribution to the formation of pH4.6SN in Cheddar (O'Keeffe et al, 1978) and Gouda (Visser, 1977) cheeses.…”

“…The comparatively low level of pH4.6SN in the CL cheese compared with that in Mozzarella cheeses in the latter studies may be attributed to the higher pH of the CL curd during plasticization and subsequent ripening (e.g., 5.45 vs. typical values of 5.1 to 5.2 at 1 d; Guinee et al, 2002), and the higher temperature used for plasticization of CL (58°C vs. 55°C in some studies in the United States). A higher pH would result in greater inactivation of rennet during heating and plasticization of the curd (Thunell et al, 1979) and would be less favorable for the proteolysis in the curd by residual rennet during storage (Tam and Whitaker, 1972;Mulvihill and Fox, 1980).…”