Yeast alcohol production vs. reproduction

[Travestian]

So I've been doing a bit of research but have had no real success in answering my question. Perhaps one of you can give me the answer?

Yeast require sugar to reproduce. They also use the sugar to produce alcohol. For a single yeast cell when it reproduces does it also produce alcohol? If it doesn't then how can you truly say that an OG of 1.060 and FG of 1.010 equals an ABV% of 6.55%?

 

[tacks]

People use sugar to produce energy, they use that energy to reproduce, too. The alcohol is produced as a byproduct of their metabolism. There is more than one pathway for sugar (carbohydrate) use in humans and yeast. The calculation you question is one that involves calculating a solution of water with sugar in it first, and that same solution with some of the sugar converted to alcohol. The easiest formula is (original gravity - final gravity)*134 to give you your abv value.

 

[GuldTuborg]

Yeast require sugar to reproduce.

Is this true? Yeast will reproduce in "stressed environments" with very few nutrients and such, generally sexually, rather than by budding, if I understand the process.

Also, what do you mean by "require"? Do you mean they tend not to reproduce in the absence of sugar? Do you mean they consume sugar in the process of reproduction, in a way that is somehow meaningfully different than during respiration? Do you mean something else?

At any rate, our gravity measurements and calculations are all pretty gross approximations. Maybe all your fears are true, but this all amounts to .0001 points out of that .050 gravity change you mentioned in your example.

Anyway, I'm clearly no expert on this matter, but felt the question needed some clarification and perspective.

 

[beergolf]

The easiest formula is (original gravity - final gravity)*134 to give you your abv value.

That is not quite right.

The formula is (OG-FG) X 131.25= ABV. I just use 131 since it is close enough.