Interpreting SG and sugar content

[ntufnel11]

With the help of this forum and other resources, I've managed to ferment a few ciders and meads with some success. I feel comfortable referencing before and after measurements of specific gravity to estimate alcohol content, but I had a follow up question on interpreting that value.

Would it be correct to interpret a 1.000 reading as containing no sugars? For example, if someone was on a specific low carb diet, would it be accurate to say that there is no sugar in such a wine based on a 1.000 reading(I know alcohol has calories and such, but I'm focusing on sugar)? If I had to make a nutrition label, would it state zero carbs like one of those spiked seltzers?

Thanks in advance

 

[jjjjfrench]

Not necessarily--depends on how much alcohol is in the liquid. Since alcohol has an SG less than 1.000, drinks such as ciders and wines can finish with an SG less than 1.000; thus if you're at an SG of exactly 1, and have some significant abv (lets say 10%); chances are there are still some residual sugars.

-J

 

[ntufnel11]

This is a great point. Any idea how much sugar we'd be talking about? A gram or two per 12oz bottle?

 

[ntufnel11]

I was surprised at how sweet my dry wines tasted. I'm trying to determine how much of this is implied sweetness from fruits and such, and how much is actual sugar

 

[jjjjfrench]

This is a great point. Any idea how much sugar we'd be talking about? A gram or two per 12oz bottle?

I really have no idea. It will depend on your abv (actually your alcohol by weight). Ethyl alcohol has a specific gravity of 0.787, so if you have a liquid that is 10% alcohol by weight (and 90% pure water), it would have an SG of 0.9787.
By estimating your abv and follow that with estimating your abw, you could back out your remaining sugar (assuming your cider were composed of only water and alcohol). I'm not sure how good of an estimate that would provide? Maybe reasonable to within 10% error?

 

[ESBrewer]

This is a great point. Any idea how much sugar we'd be talking about? A gram or two per 12oz bottle?

Much more than a gram or two. One liter of ethanol weighs about 789 grams at RT. If you have 1 liter of wine with 15% ABV, without sugar it weighs something like 0.85kg(water)+0.15l*0.789kg/l = 0.9768 kg so theres plenty of room for sugar. 2.5grams/liter of sugar will contribute about 0.1% to the weight of water so aqueous solution with 2.5grams of sugar / liter has gravity 1.001.
Typical dry white wines (alsace riesling etc.) contain 1-10g/l of sugar and I think it is common for these wines to have gravity <<1.0.