Microbial characterisation of the traditional Spanish blue-veined Cabrales cheese: identification of dominant lactic acid bacteria

Abstract

The investigation included six batches of artisan Cabrales cheese manufactured at different times of the year by two different producers and followed over a 90-day ripening period. Profound variations were found between batches due to the different mixtures of milk used from cow, goat and sheep and due to differences in temperature and humidity during ripening. Lactococci became dominant early after manufacture reaching approximately 4.0×10⁹ cfu g⁻¹ by day 3 and remained so throughout the ripening period. Lactobacilli remained at a lower level corresponding to about 3.2×10⁸ cfu g⁻¹ by day 3. Dextran-producing Leuconostoc were present in numbers of 1.0×10⁶ to 1.0×10⁷ cfu g⁻¹. Large populations of coliforms ($\approx$1×10⁷ cfu g⁻¹), enterococci ($\approx$1×10⁶ cfu g⁻¹) and staphylococci ($\approx$1×10⁶ cfu g⁻¹) were present throughout manufacture in all batches, but only the latter continued to grow during ripening, and mostly on the surface (up to 1.6×10⁷ cfu g⁻¹). Filamentous fungi, among which P. roqueforti was a majority, reached their maximum (around 5.0×10⁸ cfu g⁻¹) between day 15 and day 30. By molecular methods, all lactococcal isolates were identified as Lactococcus lactis subsp. lactis. Fifty two percent of the lactobacilli were classified as Lactobacillus plantarum or Lactobacillus paraplantarum and a further 27% as Lactobacillus casei or Lactobacillus paracasei. Dextran-producing Leuconostoc mesenteroides (58%), Leuconostoc citreum (24%) and Leuconostoc pseudomesenteroides (12.5%) were identified from the MSE agar plates, although strains of non-producing Leuconostoc lactis were also isolated from MRS.