Evaluation of several nonstarter lactobacilli for their influence on Cheddar cheese slurry proteolysis

Ten strains of nonstarter lactobacilli were evaluated for proteolytic ability in Cheddar cheese slurries by ripening anaerobically at 30 degrees C for 12 d. Fresh Cheddar curds were made under controlled conditions to minimize the influence of wild nonstarter microflora in the slurries to which nonstarter lactobacilli were added. Lactococcus Lactis ssp. cremoris SK11 was used as the starter organism for the cheese and was present in all of the slurries. The control slurries remained free of nonstarters throughout the 12 d. Reverse phase HPLC of water-soluble extracts of the slurries indicated differences in peptide profiles between slurries with nonstarter compared with the control (containing only Lc. lactis ssp. cremoris SK11) and between slurries with different nonstarters. Total free amino acids and individual amino acids concentrations also suggest varied proteolytic capabilities between nonstarter strains in control and other cheeses. Slurries containing Lactobacillus helveticus released more amino acids (0.7 mg of Leu/mg of cheese extract) than did slurries containing Lactobacillus casei, Lactobacillus paracasei, or Lactobacillus curvatus (0.4 to 0.6 mg of Leu/mg of cheese extract).