Wine Faults and Flaws. Keith Grainger
a) Sensory detection thresholds depend upon many criteria, including the presence of other compounds and the wine matrix. The figures stated have been extrapolated from numerous sources.
Table 2.4 Compounds contributing to the varietal aromas of Sauvignon Blanc wines.
| Aroma | Thiol | Sensory detection thresholda) |
|---|---|---|
| Boxwood – broom, cat's pee | 4‐Mercapto‐4‐methylpentan‐2‐one | 0.8–3.3 ng/l |
| Citrus zest and peel | 4‐Mercapto‐4‐methylpentan‐2‐ol | 55 ng/l |
| Grapefruit, passion fruit | 3‐Mercaptohexan‐1‐ol | 60 ng/l |
| Mango, guava, passion fruit | 3‐Mercaptohexyl acetate | 4 ng/l |
| Cut grass | 1‐hexanol | 4.5 μg/l |
| Smoke, gunflint | Benzenemethanethiol | 0.3 ng/l |
| Aroma | Methoxypyrazine | Sensory detection threshold a) |
| Green pepper, grass | 2‐methoxy‐3‐isobutyl pyrazine (iBMP) | 1–2 ng/l |
a) Sensory detection thresholds depend upon many criteria, including the presence of other compounds and the wine matrix. The figures stated have been extrapolated from numerous sources.
It may sometimes be helpful for the taster to consider wine aromas in basic groups:
Fruits (primary aromas);
Flowers (primary aromas);
Spices (primary, secondary, and tertiary aromas);
Vegetables (primary and tertiary aromas);
Oak aromas (secondary aromas);
Other aromas.
Of course, it is possible to divide each of these basic groups into subgroups. For example, the fruits group might be divided into citrus, green, red, stone, and tropical fruits. Dried fruits may also be included. Each subgroup contains individual aromas and flavours.
All aromas detected during nosing should be noted, and when detailing individual descriptors, these may be linked to known varietal characteristics. For example, green apple, lime, peach, and mango are just some of the aromas that may be associated with Riesling. Strawberry, raspberry, red cherry, green leaf, and mushroom are typical aromas associated with Pinot Noir. The detection of any oak related aromas including vanilla, toast, nuts, and coconut may warrant interpretation (barrels/beans/chips?).
2.7 Palate
2.7.1 Palate Sensations
Palate is a convenient expression to describe the sensations a wine gives once in the mouth. Palate may comprise a ‘complex combination of the olfactory, gustatory, and trigeminal sensations’ [7]. In this part of the tasting process, we assess the taste and tactile sensations detected in the mouth, particularly on the tongue, and the flavour characteristics detected as a result of the wine's volatile compounds being breathed through the retro‐nasal passage at the back of the mouth and transmitted to the olfactory bulb. The impressions of aromas sensed retro‐nasally are often different from those sensed nasally. The sensory cells within the mouth are mostly contained within the 5000 or more taste buds on the tongue – young people may have up to 10 000 active taste buds. There are also taste buds on the roof of the mouth and the back of the throat, which is why some people claim to only get 100% of what the wine has to offer if they swallow rather than spit. Interestingly, a recent study has indicated that olfactory receptors are functionally expressed in taste papillae [11]. In other words, it may be possible for the tongue to ‘smell’.
A reasonable quantity of wine should be taken into the mouth. If it is too little, the wine will be diluted and modified by saliva. It is important to breathe air through the wine in the mouth to vaporise the volatile compounds. Accordingly, a free passage is needed to and from the nose to enable transmission of these aromas. If a person has a blocked nose, it is not just the sense of smell that disappears, but most of the sense of taste. The taste