Influence of Brettanomyces ethylphenols on red wine aroma evaluated by consumers in the United States and in Portugal

Brettanomyces may add complexity to wine at low concentrations but at high concentrations, can result in objectionable wines. The objective of this study was to determine the concentrations at which consumers from two different locations were able to detect Brettanomyces volatile compounds present in a red wine. A red wine blend, used in both countries, was spiked to create five treatments containing different concentrations of 4-ethylphenol (4-EP), 4-ethylguiacol (4-EG), and 4-ethylcatechol (4-EC) in a 5:1:1 ratio, respectively. These treatments were evaluated by consumers in the United States and Portugal (n = 121) using a difference from control test. Consumers were also classified as having low, medium, or high wine knowledge. Among the spiked samples, the greatest degree of difference was found between the second and third treatments, corresponding to reported detection and recognition threshold ranges of 4-EP and 4-EG. For some treatments, consumers from Portugal classified in the medium or high knowledge level reported significantly higher mean differences from the control than those in the low knowledge group (p < 0.05). Results demonstrated consumers' ability to detect differences in red wines due to Brettanomyces volatile compounds. Results provide useful context on how wine knowledge and cultural variants may affect the detection of Brettanomyces