Abstract Proteolysis assessment, total acidity, pH, and determination of lactose and organic acids by HPLC, as well as descriptive sensory evaluation by an expert cheese judge were used to evaluate eight 60-day-old commercial Cheddar cheeses from a local processor. Samples of acceptable and defective Cheddar cheese quality were identified in a blind test on the basis of statistically different organic acid profiles and lactose levels. Proteolysis levels were not conclusive: however, total acidity and pH appeared to follow the quality differences identified by HPLC analysis. This study suggests that objective measurements could complement subjective tests and thus facilitate the detection of Cheddar cheese flavour quality problems.