Sucrose, aka table sugar, is completely fermentable. Once inside the yeast cell it is broken down into glucose, but it is 100% fermentable providing other nutrients are present.
Fred
None of the following information is my own, it is merely my experience and interpretation of what I have read and experienced. I may be completely off base on this (I don't think so), take it as you wish or not.
Sucrose (disaccharide or C12, H12,O11) aka table sugar, is fermentable after the yeast brakes it down into fermentable sugars aka fructose (C2, H12, O6) and glucose (C6, H12, O6) (monosaccharides). To say it is completely fermentable I believe is not a correct statement, there are still four carbon molecules unaccounted for and it is missing one oxygen. It is speculated that the one oxygen molecule is to be pulled directly from the beer as it ferments. Given enough time the yeast will break the sucrose into fermenable sugars, time being the key factor. This is why you get a sweet smell to beer when enough is added (No more than 15%). From my experience the yeast does not have enough time and falls out of the beer before is has completely fermented the sucrose out. Which is why I stated that there is lots of sucrose that they yeast can not turn into alcohol. I did not state that it would not convert at all, merely that there is a large amount that still remains. I also stated that sucrose wont do much. This was in reference to ABV. In my experience I have only been able to raise the ABV an average of 1 to 1.5 points by adding either Candi sugar or Table sugar.
There may be a correlation to the flocculation of the yeast and the amount of residual sucrose left in the beer. I will have to try this with a nice Hefe to find out, but this is speculation on my part.
Acidic hydrolysis can be used to achieve the hydrolysis of sucrose into glucose and fructose (See WIKI in previous post). Both of which are much easier/quicker for the yeast to ferment out in comparison to breaking the Sucrose molecule chain into fermentables.
Wow that was long winded
Cheers!
Preston