Bob,

It sounds like you're talking about the difference between 'polish
filtration' and 'sterile filtration'. Polish filtration is often done
with a 1 - 5 micron filter. It will not exclude yeast or many other
microbes. If you need to remove yeast with certainty you need to
filter through a 0.45 micron filter (or smaller).

Having said this, Port is usually fortified to nearly 20% alcohol.
That should be pretty effective at killing your yeast population.

RD


Bob Becker wrote:
> I'm in the process of making a port wine kit.
>
> As part of the process they specify filtering to get rid of
> the yeast to eliminate the possibility of further fermentation
> of the residual sugars once the port is bottled.
>
> I just re-read the previous thread about filtering, but it seemed
> geared toward clarification rather than filtering yeast.
>
> Is there a difference, or will any filtration system clarify
> and also eliminate yeast?
>
>
> --
> Bob Becker
>
> www.becker.org