Why “vinous” is the catchall term for what we can’t describe

A wine’s scent is one of the best indications of its quality. The hedonic effects of wine are influenced by hundreds of volatile aroma compounds, making it one of the most complex of food and beverage products.

While those aromas derived from fermentation are the most important contributors to the overall aroma of a wine, the parts-per-billion (ppb) levels of many aroma compounds make understanding their sensory relevance a difficult task.

Of the several hundred volatile aroma compounds that have been identified in wine and classified into different chemical families based on their roles in the wine matrix, the most important are higher alcohols, esters, and fatty acids that create the general aroma profile of a wine often described as “vinous.”

This profile isn’t significantly altered by changes in the concentrations of single aroma molecules. Even when a diverse group of these compounds have concentrations above their perception thresholds, they are integrated components of the wine matrix, making it difficult to perceive or differentiate them using individual aroma descriptors. Despite not making an individual contribution to the scent of a particular wine, they are critical for enhancing or depressing the perception of other aromas.

This complex non-aromatic matrix in which aroma compounds are dissolved varies greatly among different types of wines with different predominant aromas, contributing a specific typicity to each. Recently, the effects of non-aroma compounds present in the wine matrix have been shown to be important for the perception and release of wine aroma; the compounds we can’t differentiate interact with those we can to directly influence the scent of wine.

In general, wine aromas can be classified into varietal, fermentative, and aging aromas. Most wine aroma compounds, including those present only as non-aromatic or bound precursors, are produced or released during fermentation due to microbial activity.

Among them are three families that contribute to the distinct
varietal characteristics of wines: terpenes, methoxypyrazines, and pleasant-odor thiols. Terpenes, which include linalool, (E)-
hotrienol, citronellol, geraniol, nerol, (−)-cisrose oxide, and a-terpineol, are the most important aromatic monoterpenoids and
contribute floral, fruity, and citrus aromas to wine, while their non-aromatic monoterpene precursors are the most significant among many grape varieties.

Varietal thiols have strong effects on the sensorial properties of wines because of their very low detection thresholds; they comprise approximately 10% of the volatile components detected in foods and beverages and are prevalent in many white wine varieties, including Sauvignon Blanc, Macabeo, Gewürztraminer, Riesling, and Verdejo.

Low-volatility compounds like thiols enhance wine aroma, while
high-volatility compounds are most associated with defects including rotten egg aromas and secondary reductive odors such as cooked vegetables, onion, and cabbage. They only exist in trace amounts in berries and are formed during fermentation as a byproduct of yeast.

Given the deceptively complex nature of wine aromas, generic-sounding descriptors like “vinous” and even “grapey” can both be considered accurate indicators of quality.