Estimating a “consumer rejection threshold” for cork taint in white wine

Cork taint in wine produced by 2,4,6-trichloroanisole (TCA) is characterised by generally unacceptable musty or earthy odours. Estimates of TCA threshold in wine have been reported in the low parts per trillion (ppt) range, although it is not clear at what levels TCA begins to render a wine unacceptable. We conducted two studies to address this question by using a method that combined a paired preference test with a method of constant stimuli threshold procedure. The aim was to determine the point at which wine consumers would begin to reject a wine containing TCA, which we termed the consumer rejection threshold (CRT). Regular white wine consumers (Ss) received pairs of samples of white wine--one spiked with TCA in eight ascending concentrations--and were asked to indicate which of the samples was preferred. Detection thresholds (DT) for TCA in wine were also determined using triangle tests. The CRT and DT were 3.1 and 2.1 ppt, respectively. CRT and DT were significantly positively correlated with one another, and negatively correlated with TCA knowledge. A replication provided a similar CRT value, and suggested that a percentage of consumers are either highly insensitive to TCA or do not find it objectionable. These results suggest that the use of this method may provide a rational basis on which to assess the real impact of TCA in white wine.