Creation and Use of a Brettanomyces Aroma Wheel

Abstract

Summary Goals: The ability of the yeast Brettanomyces to produce negative aroma attributes from grape phenolic precursors is well known. However, this yeast synthesizes a broad array of aroma-active compounds in wines, some of which are valued or deemed positive in certain wine styles or matrices. To better understand the spectrum of positive and negative aroma traits associated with the presence of Brettanomyces in wine, we created an aroma wheel to categorize and describe the variety of aroma impacts of this yeast on the basis of analyses of aroma-active compound production from spiked precursor compounds in a model controlled environment. Key Findings: The Brettanomyces aroma wheel categorizes many of the aroma descriptors associated with wine spoilage by Brettanomyces . Terms on the wheel may categorize aroma-active compounds generally associated with microbial infection of both Brettanomyces and lactic acid bacteria (LAB). There is no evidence for a Brettanomyces strain that produces only positive characters in wine. Impact and Significance: A comprehensive Brettanomyces aroma wheel was generated with different strains under controlled product–precursor conditions and tested for broader utility in commercial winemaking. Thirty commercial wines described by wine critics using two or more of the identical or similar terms to those found on the Brettanomyces aroma wheel were obtained from a retail outlet. All wines purchased had evidence of presence of Brettanomyces , LAB, or both. The inner circle, or general categories of the wheel, were used more commonly by critics in describing wines and the specific terms (outer wheel) less generally used as commercial wine descriptors. The terms presented on the aroma wheel can therefore be used to determine if a wine is likely to have sensory characteristics contributed by Brettanomyces or LAB. This appeared to be particularly true for the general categories “savory,” “woody,” “spicy,” “floral,” “earthy,” “chemical,” and “animal.” Thus, the wheel can be used to identify wines with a strong, but not necessarily negative, microbial signature.