Influence of bacteriocin-producing Lactococcus lactis on the ripening of Cheddar cheese.

Lactococcus lactis subsp. lactis L3A21M1, which produces the bacteriocin lacticin 481, was investigated for its ability to improve cheese ripening. Three laboratory-scale Cheddar-type cheeses were produced from pasteurized cow's milk in triplicate trials: control cheese made with a commercial starter culture containing Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris; Bac +  cheese produced with the same commercial starter culture plus Lactococcus lactis subsp. lactis L3A21M1 as a producer of bacteriocin (lacticin 481); and Bac- cheese produced with the same commercial starter culture plus Lactococcus lactis subsp. lactis L3B1M7 as a non-bacteriocin producer. The microbiological, physicochemical, textural, proteolytic, and peptide profiles of cheeses were evaluated during the 28-day ripening period. The bacteriocin-producing Lc. lactis L3A21M1 increased proteolysis throughout the ripening process, as shown by the higher (p < 0.05) values for nitrogen fractions and free amino acid content in the cheeses. The textural properties were also influenced by the addition of the Lc. lactis culture, resulting in a softer cheese. The use of the bacteriocin-producing strain Lc. lactis L3A21M1, as an adjunct culture, thus accelerates the proteolysis of Cheddar cheese by inducing the lysis of the starter culture and increasing the content of free peptides and amino acids during ripening. In addition, the amount of hydrophobic peptides decreased significantly (p < 0.05) during ripening in the cheese with the bacteriocin producer.