Effect of ripening temperature on the growth and significance of non-starter lactic acid bacteria in Cheddar cheese made from raw or pasteurised milk

Two cheese-making trials were conducted, each involving four cheeses, two made from raw milk (R1, R8) and two from pasteurised milk (P1, P8), and ripened at 1°C (R1, P1) or 8°C (R8, P8). The 1-day-old R1 and R8 cheese in trials 1 and 2 contained ～10⁴ non-starter lactic acid bacteria (NSLAB) g^?1. In trial 1, no NSLAB were detected in 1-day-old P1 and P8 cheeses while those in trial 2 contained 10² cfu g^?1. In both trials, the maximum differences between the number of NSLAB in the cheeses ripened at 1 or 8°C were observed at 4 months, when the number of NSLAB in cheeses ripened at 8°C were 3 log cycles higher than in those ripened at 1°C. At the end of ripening (6-months), the number of NSLAB in P8 and R8 were ～2 log cycles higher than in P1 and R1 cheeses, respectively. Primary proteolysis in the cheeses was markedly affected by ripening temperature, but not by pasteurisation of the cheese milk. Urea-polyacyrlamide gel electrophoretograms and reverse-phase (RP)-HPLC of the water-soluble fraction showed differences between cheeses made from raw or pasteurised milk and between cheeses ripened at 1 or 8°C. The concentration of amino acids and fatty acids were in the order R8>P8>R1>P1. Commercial graders awarded highest flavour scores to the R1 cheeses during gradings at 4, 5 and 6 months. A sensory panel found that most flavour and aroma attributes and maturity were in the order of R8>P8>R1=P1. The results of this study suggest that NSLAB play an important role in the development of flavour in Cheddar cheese by contributing to the production of amino acids and fatty acids.