1) Adding enough alcohol will stop fermentation. Sorbate doesn't stop
fermentation. It prevents yeast from starting.

2) At the alcohol levels that port has, nothing will grow in it. You
can use regular levels of SO2 for a "ruby" style port or no SO2 for a
"tawny" style (more oxydation).

wrote:
> I am making port this year for the first time. Using Cab grapes, I'll
> be mixing it with brandy. I have a couple of questions I'd like to put
> up to the group to check myself:
> 1) do I have to add potasium sorbate to halt fermentation, or will the
> brandy do the trick?
> 2) I'll be taking the juice off the must at about 15 Brix (started at
> 26) and mixing 1.5 gal brandy with 3.5 gal wine. Do I need to worry
> about sufiting this process both the carboy and the port itself, or is
> the strength of the final product enough to no worry about that? (I'll
> probably do it anyway)
> thanks
> Marc