Proteolysis and formation of volatile compounds in cheese manufactured with a bacteriocin-producing adjunct culture

Hispanico cheese, a semi-hard Spanish variety, was manufactured from a mixt ure of pasteurized cows' and ewes' milks (4:1) using a commercial mesophili c LD-type starter comprising Lactococcus lactis subsp. cremoris is, Lc. lac tis subsp. lactis, Lc. lactis subsp. lactis var diacetylactis and Leuconost oc mesenteroides subsp. cremoris. Varying amounts (0-1.0 g/kg) of an Entero coccus faecalis INIA 4 culture in milk were added as a bacteriocin-producin g adjunct. Differences in pH between cheeses manufactured with and without the bacteriocin producer did not exceed 0.11 pH units. Starter lactococci l ost viability more rapidly in cheeses made with the bacteriocin producer, w hich reached counts of up to 6 x 10(7) cfu/g during ripening. Aminopeptidas e activity in 1-d-old cheese made from milk inoculated with 1.0 g bacterioc in-producing culture/kg was twice that in control cheese. Degrees of overal l proteolysis and levels of total free amino acids in 45-d-old cheese made with 1.0 g bacteriocin-producing culture/kg were 1.80-fold and 2.17-fold th ose in control cheese of the same age. Inoculating milk with 1.0g/kg bacter iocin-producing culture reduced the level of hydrophobic peptides in the re sultant cheese. increased the concentrations of 3-methyl-1-butanal, diacety l and acetoin, and resulted in the highest scores for flavour quality and f lavour intensity throughout ripening.