Vinous calorie counting
The most frequently asked question over the holiday season was “how many calories in a glass of wine?” Or variations on a theme, such as “does red wine have more calories?” After a little research here is what I came up with.
The two calorific components in wine are sugar and alcohol. Grape juice before fermentation is very sweet and has approximately 50% more calories than Coca-Cola, according to UK wine critic, Simon Woods.
During fermentation, yeasts transform sugar into alcohol, although the yeasts never quite complete the job. There is always at least a tiny bit of residual sugar in even dry white and red wines. During the fermentation process, some calories are lost therefore a litre of wine will have fewer calories than a litre of the grape juice that produced it.
A gram of sugar has 4 calories. That’s straightforward but calculating the calories in alcohol is a little more complicated.
A litre of wine with 13% alcohol by volume contains 130ml of alcohol. A 750ml bottle of the same wine has 97.5 gms of alcohol. One ml of alcohol weighs 0.8 gms. Alcohol has 7 calories per gm. Therefore a 750ml bottle of 13% alcohol wine has 97.5 x 7 x 0.8 = 546 calories plus the calories represented by any residual sugar. If the wine was dry with just 1 g/l of residual sugar you would need to add an extra .75 x 1 x 4 = 3 calories, effectively negligible.
Here are some of my calorie calculations per 750ml bottle for a few common wines:
- Sauvignon Blanc 13% alc, 5 g/l RS = (130 x .75 x 7 x 0.8) + (.75 x 5 x 4) = 561 calories
- Riesling 12.5% alc, 20 g/l RS = (125 x .75 x 7 x 0.8) + (.75 x 20 x 4) = 585 calories
- Chardonnay 14% alc, 2 g/l RS = (140 x .75 x 7 x 0.8) + (.75 x 2 x 4) = 594 calories
- Syrah 14.5% alc, 1 g/l RS = (145 x .75 x 7 x 0.8) + (.75 x 1 x 4) = 612 calories
Less difference than I had anticipated.
Let’s try a “Lifestyle” wine with 9.5% alc and 20 g/l RS = (95 x .75 x 7 x 0.8) + (.75 x 20 x 4) = 459 calories.