Two extraction methods were applied to measure the thiobarbituric acid reactive substances (TBARS) values of vacuum packaged grass-fed beef steaks that were aged under four temperatures and five different time interval combinations to capture a range in lipid oxidation. The relationships between TBARS values and consumer assessment of flavour liking, flavour intensity and overall liking, were examined. M1 values had a normal distribution (0.02 to 2.55 mg MDA/kg), whereas M2 had a skewed distribution with the majority of the values <1.0 mg MDA/kg and the maximum value being 10.72 mg MDA/kg. No relationship was found between these methods. Interestingly, there were no significant effects of TBARS value on the sensory results, irrespective of the method used. This suggests that untrained consumers cannot detect abnormal flavour development due to high levels of lipid oxidation (TBARS) as indicated by the TBARS test, and are therefore undiscouraged when tasting these beef samples.