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

Low moisture part-skim (LMPS) Mozzarella cheeses were made with single culture (SC) of Streptococcus thermophilus or mixed culture (MC) of Streptococcus thermophilus and Lactobacillus helveticus using 1x or 6x of cheese coagulants chymosin or Cryphonectria parasitica (CP). Cheeses were analyzed for total solids, fat, protein, ash, salt, and calcium on day 1. Changes in melt characteristics and proteolysis during storage (4degreesC) were monitored on 1, 7, 15, and 30 days (d). After 30 d storage, melt area as measured by modified Schreiber test increased only by approximately 2 times in cheeses made with SC as against 3-4 times in the cheeses made with MC. On d 30, creep test showed that the fall in height decreased by approximately 4-5 times in the SC cheeses but approximately 7-9 times in the cheeses made with MC when compared with the values obtained on d 1 for corresponding cheeses. Melt characteristics on d 7 for cheeses prepared with MC almost corresponded to that of d 30 cheeses made with SC, suggesting faster ripening and increase in melt of cheeses made with MC. Soluble nitrogen was also higher in MC cheeses as compared to those made using SC only. The degradation of total alpha(s)-casein was higher in the chymosin cheeses and that of beta-casein in the CP cheeses. The degradation of casein fraction f((24-199)) was higher in MC cheeses as compared to those prepared with SC only. After 30 d storage, the highest percentage breakdown of alpha(s)-casein was approximately 75% in cheeses made with MC using 6x chymosin and that of beta-casein was approximately 50% in cheese samples prepared with MC using 6x coagulant from Cryphonectria parasitica. Meltability of Mozzarella cheese was better correlated to hydrolysis of beta-casein and was comparable to soluble nitrogen but least to alpha(s)-casein.