Proteolysis of Reduced-Salt Cheddar Cheese as Affected by Casein to Fat Ratio, Rennet, and pH at Drainage
Effects of change in pH at drainage (6.2, 5.9, and 5.6), rennet concentration (0.1 and 0.3 mL rennet/L of milk) and casein to fat ratio (0.6, 0.7, and 0.8) on proteolytic characteristics of salt-reduced Cheddar cheese were investigated. Chemical composition, lactic acid bacteria and proteolysis were measured. At the same drainage pH, cheeses with C/F ratio 0.6 had significantly higher moisture and ash content compared other ratios. The pH decreased significantly from day 0 (right after pressing) to 120 day and then remained constant. Total LAB growth in cheeses made with 0.3 ml rennet /L was higher at the same C/F ratio and pH at drainage of 6.2. Total plate count at day 180 was significantly higher compared with day 0 (right after pressing). At the same drainage pH, C/F ratio and storage time, water soluble nitrogen contents in cheeses made with 0.3 ml/L rennet were higher compared with 0.1 ml/L. Total free amino acids and trichloroacetic acid-soluble nitrogen contents increased significantly during storage. More hydrophobic peaks appeared as the rennet concentration was increased from 0.1 to 0.3 ml/L. Extra-hydrophobic peptides % in cheese at day 0 and pH at drainage of 5.6, were higher compared to cheese where pH at drainage was 6.2. Increase in C/F ratio and rennet concentration, especially at low pH, showed similar proteolysis as cheese containing 2.5-3% salt.