Effect of a commercial adjunct culture on proteolysis in low-fat Feta-type cheese

The effect of a commercial adjunct culture (CR-213, containing Lactococcus lactis subsp. cremoris and Lactococcus lactis subsp. lactis) on the proteolysis in low-fat Feta-type cheese was studied. Two controls, a full-fat cheese (similar to220 g kg(-1) fat) and a low-fat cheese (similar to70 g kg(-1) fat) made using the standard procedure were also prepared. The effect of adjunct culture on proteolysis, as examined by polyacrylamide gel electrophoresis of cheese and water-soluble cheese extracts, was marginal. Reverse-phase HPLC analysis of water-soluble cheese extracts indicated only relatively minor differences in proteolysis between controls and experimental cheeses. Proteolysis, as measured by the percentage of total nitrogen soluble in water or in trichloroacetic acid (120 g L-1), was not affected by the addition of adjunct culture. However, the levels of total nitrogen soluble in phosphotungstic acid (50 g L-1) and the concentration of free amino acids were affected by the adjunct culture and were significantly (P<0.05) higher in the experimental cheeses than in the low-fat control cheese. (C) 2003 Elsevier Science Ltd. All rights reserved.