Vegetative aroma: Sensory definition, chemical interpretation (and ultimately) causal explanation.

Over the past several years we have made significant progress toward improving our understanding of vegetal aromas in wines, particularly in the varietal Cabernet Sauvignon. Our studies indicate that experts (i.e., winemakers) use many different criteria to classify wines as vegetal. Although there is some consistency among winemakers in the use of vegetative terminology, similar aromas may all be categorized together (Objective 1). Descriptive analysis with trained panelists indicated that trained panelists are able to distinguish among different qualitative differences within the overall category of vegetal terms (Objective 2). Therefore when communicating information about vegetal aromas, care must be taken to ensure that the terminology is well-defined (Objective 1 and 2). While methoxy pyrazines (e.g., 3-isobutyl-2-methoxypyrazine, IBMP) are frequently associated with bell-pepper character, other compounds may also play an important role in vegetal aromas (Objective 3). Interactions between vegetal and fruity aromas can serve to mask perception of vegetal aromas in some cases (Objective 2). In addition, interactions with matrix components such as polyphenols and tannins may result in decreased flavor volatility and perception (Objective 2). Viticultural practices can influence IBMP levels and sensory perception of vegetal aromas. However, growing region, row orientation, and vine microclimate all interact in complex ways to influence composition and sensory properties (Objective 4).