Ian Sutton wrote::)
Yes this one does cause a bit of debate around the table.
In principle I agree with the definition, though in the absence of a residual sugar amount noted on the label I'd refer to my perception of residual sugar. FWIW, the NZ wine critic Michael Cooper uses the following definition in his wine buyers guide:
Dry: less than 5grams/litre of sugar
Med-dry (aka off-dry): 5-14 grams / litre
Med: 15-49 grams / litre
Sweet: 50+ grams / litre
By this count most reds are dry and a large proportion of whites, even though some reds will have a somewhat sweet taste from the ripe fruit.
However some wines still taste sweet when there is little or no residual sugar, either due to the strength of the fruit (where I'll aim to refer to it as "fruit-sweet but otherwise dry") or the effect of alcohol, which can give an impression of sweetness (I might refer to possible alcohol related sweetness).
with off-dry or sweet wines, it's very useful to consider the acidity levels, as high acidity can work stunningly well with sweetness, whereas sweetness without acidity, tends towards flabbyness and supermarket Liebfraumilch or Lambrusco.
Another good question!
regards
Ian
FWIW, at NZ wines shows, the cutoffs for dry / medium and medium sweet differ a little from Michael's definitions. Dry can be up to and including 7.5 grams per litre (g/l) of residual sugar (rs), medium starts at the cutoff for dry and goes up to 30g/l rs, medium sweet is 30 to 50 g/l rs and sweet is over 50 g/l rs.
All NZ wine shows have dry and medium classes for the aromatic wines and this can vary depending on theshow. In addition the Royal Easter Show has dry/medium subclasses for the non-aromatics.
In the Air NZ Wine Awards - Riesling, Pinot Gris and Gewurztraminer are split into dry and medium subclasses, where dry is up to (but not including) 7g/l rs and medium is 7g/l rs to 30g/rs. All wines from 30g/l rs to 50g/l rs are considered medium sweet and sweet is over 50g/l rs. There is no dry/medium split for Sauvignon Blanc, Chardonnay and other whites.
In the New Zealand International Wine Show, and the Liquorland Top 100, the cut off for dry in the Riesling, Pinot Gris and Gewurztraminer classes is up to (but not including) 7.5 grams per litre of residual sugar. Ditto as above for Chardonnay, Sauvignon Blanc, Viognier, etc.
In the Royal Easter Wine Show, they also split Chardonnay, Sauvignon Blanc and Semillon into dry and medium subclasses and for a wine to be in a dry class, residual sugar must not exceed 5g/l rs. However in the aromatics and other specified and unspecified white classes, residual sugar must not exceed (therefore includes) 7.5g/l rs for a wine to be correctly entered in the dry subclass.
Is it confusing - or what? And then, as you say, many people's perception of sweetness can be altered by other factors, including acidity. Last week, when teaching a wine class I poured a Riesling that had 29 g/l rs and 9 g/l total acidity and to everyone there, it tasted much drier and much lower in acid than it really was.
Cheers,
Sue