I was making a 4L yeast starter from 1# of DME yesterday. After the hot break there was the usual "hot break trub" suspended in the resulting wort. I really hate the way the trub looks when suspended in the wort while it is on the stir plate, and that got me wondering....
When propagating yeast from a "new vial" (generation 0), I generally make 2 * 2L starters. I use 1 2L starter for the upcoming batch, and I "wash" the second for future use. With the 2L batch for future use, I leave the yeast on the stir plate for ~3 days, then move it to the fridge for a day or two. I then decant off ~1.2L of the beer, and return the flask to the stir plate for ~10min. I then fill six 4oz sterilized mason jars with the yeast slurry, label them and return them to the fridge.
....how much of that slurry is really hot-break trub? I don't know the answer, but it gave me another reason to dislike it, so I thought I would be proactive about it. I took the 4L wort and filtered it into another flask first using a paper towel in a large funnel, and then again using a large coffee filter. The process was more than a bit messy, and required more than one paper towel and a couple of coffee filters, but the resulting wort was sparkling clear. Once done, I re-boiled the wort for another 15 minutes, and it remained beautifully clear. The final volume was 3.75L, meaning I "lost" about 250ml in my filtration process (~1/16th). I pitched my yeast happy in the knowledge that when all is done all of the trub will be yeast and fermentation byproducts.
Will this make a better starter? I really don't know. It sure **looks** better, lol, but that isn't hugely important; what it got me thinking about was the viability of filtering my wort in its travels from my boil kettle to my fermenter. I have a 25 gallon boil kettle and pass the wort through a cold plate on its way to my 27 gallon Blichmann "fermentators". I use the "Swirl" method in my Boil Kettle, but still get more hot/cold break & hop mess in my fermentor than I would like (Yes, I know the whole point of conicals is the ability to dump the trub, but dumping "costs beer" and tends to re-suspend some of the trub in the beer....) .
I have been thinking about adding a filter to the path from the boil kettle to the fermenter (most likely after the chill plate), but am hesitant for two reasons: 1) My experience with the 4L starter tells me that a large filter surface area is required because the particulates quickly clog the filtration media. 2) One more thing to clean/sanitize. A "sand" type filter like used in pools is fabulous for this type of filtering, but is a sanitation nightmare. A paper type filter like used in a SPA is easy to sanitize, but is highly prone to clogging. A "sediment" filter like used in domestic well filtration is fairly easy to sanitize and less prone to clogging than a paper type filter, but allows fairly large particles to pass, hence making it of questionable value.
At the end of all of this thinking, I am wondering if perhaps I am just thinking too much, LOL. Is the pursuit to clarify my beer going too far? I am not really looking for answers, just thinking this through and thought I would see what others thought.