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Background and Aims: Rotundone is responsible for peppery aroma in wine. This note is not appreciated by all consumers, which indicates that rotundone might be considered as a taint above a certain concentration. The current study aimed at determining a consumer rejection threshold for rotundone in Duras red wine. Methods and Results: Consumers (n = 62) received pairs of samples consisting of a base wine and the base wine spiked with an ascending concentration of rotundone and were asked to indicate which sample they preferred. Anosmic respondents detected through triangle tests represented 31% of the panellists. For these panellists, the wine spiked at the lowest concentration was significantly rejected suggesting that rotundone might induce a trigeminal sensation and/or is involved in molecular mechanisms of flavour reduction. For remaining panellists, we were not able to determine any consumer rejection threshold. We identified three clusters of consumer profiles. The first cluster preferred a moderate concentration of rotundone and rejected a high concentration. The second cluster, mainly composed of young consumers, preferred the Control. The last group appreciated peppery wines especially at high concentration. Conclusions: The response of consumers to rotundone is complex, and peppery notes are perceived positively or in a neutral manner by most consumers with the exception of young panellists. Significance of the Study: Our results may assist grape growers producing Duras and other cultivars, where rotundone makes a sensory contribution, to adapt their products to consumer profiles. They also open new fields of investigation into mechanisms involved in specific anosmia to rotundone.

Aim: Rotundone and 3-isobutyl-2-methoxypyrazine (IBMP) are two potent aroma compounds responsible for pepper and bell pepper notes in red wines, respectively. The aim of the study was to modulate, through common viticultural practices, the volatile composition in these two molecules of Fer red wines from a temperate climate wine region with very cool nights, located in the southwest of France.Methods and results: Three viticultural practices (leaf removal 10 days after berry set, removal of lateral shoots, and delayed harvest 7 days after the control) were investigated in 2015 and in 2016. Rotundone concentrations up to 69 ng/L were found in experimental wines. IBMP concentrations were below perception level in wines from 2016 and below detection level in wines from 2015, a vintage with particularly hot climatic conditions between berry set and bunch closure. Delayed harvest induced an increase in rotundone concentration while leaf removal and the removal of lateral shoots had no significant impact on rotundone concentration. Delayed harvest and the removal of lateral shoots were the most efficient practices to decrease IBMP in wines. The three techniques made it possible to increase the odour activity values (OAV) ratio of OAV rotundone to OAV IBMP, with the greatest impact observed for delayed harvest.Conclusion: According to our results, delayed harvest appears to be the best practice to modulate the volatile composition of Fer wines toward an increase in the OAV rotundone to OAV IBMP ratio.Significance and impact of the study: Our results may assist local grape growers to modulate the volatile composition of their wines.