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,
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:
You can get sterile filtration equipment easily down to the 0.1 micron range. I purchase 0.45 micron depth filters (nom), which (as of yet) have not permitted any re-fermentation of any wine.
I'll let you know in 2 years whether or not the honey meads have started back up.
The filter sheets run about 50 cents apiece, and are each easily capapble of doing 10 gallons+.
Jas> Bob,
You can get a lot of filtration capacity by using a 0.45 micron depth filter to catch the major junk, with a 0.45 micron absolute filter (of smaller size) downstream of the depth filter to catch the little bit of tiny stuff that makes it through the depth filter. Depth filters take a lot longer to load up and are usually rated for 95-99% efficiency, whereas absolute filters can give you 99.9+% filtration efficient but load up quickly if you put the dirty wine directly to them. The more loaded a filter element gets, the greater the chance for 'punch through' (where high velocity flow in a small area can occur due to the high pressure drop across the major portion of the filter element).
In all cases, you want to make sure the filter element does not have gaps around the edges/ends. Those gaps will allow stuff to get around the filter element. Many people use a permanently sealed cartridge absolute filter to minimize filter 'seating' problems. If I'm not using a permanently sealed 0.45 um absolute filter unit, I like to use the spear-point single open-ended with double o-ring filter types. There are less expensive double open-ended filter elements that use flat washers to seal both ends, but they don't seal as well. They USUALLY seal, but not always.
Commercial wineries typically use a diatomaceous earth pad filter system for rough filtering, and a 0.45 micron absolute filter just ahead of the bottling line to catch the odd fragments of yeast and ml bacteria.
Gene
snipped-for-privacy@gmail.com wrote:
I agree with RD. Port is usually at such a high alcohol level that it will not restart. Also port is usually aged a long time so it can be bulk aged and will clear on it's own. I would not consider filtering a port.
Ray
That's the impression I'm getting. I just racked it from the primary to the secondary, and I'm getting no bubbles of any kind. If it doesn't restart over the next month or two I can't imagine how bottling it would restart any fermentation.
If it has just finished fermenting then it is not port. Port is "fortified" meaning additional alcohol is added to the wine to raise the alcohol content.
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