Reducing the taste of yeast

There are good answers about removing yeast cells from existing homebrew.

But your question asks about "yeast taste" - this is not just particulates. So I wanted to add an answer covering some of this.

There are many flavours generated by yeast during fermentation. There are two ways to common ways minimise these flavours:

1. Use a "POF Negative" yeast
2. Ensure a good fermentation

Yeast Selection

Brewers yeasts are divided into POF Positive or POF Negative strains. Without going into too much detail, this indicates whether the yeast is biologically predisposed to produced Phenolic flavours. Lager strains, and many ale strains are POF-negative. They produce a "clean" flavour profile. A good example would be Safale US-05.

That leaves the POF positive yeasts - in this section are yeasts used to produce a lot of Belgian beers, and also German Hefeweizen. These produce many notable aromas & flavours - and are used in these styles because of this.

Good Fermentation

Most of the yeast flavours are produced during the first few days of fermentation. Factors influencing this are also how healthy the yeast is, how abundant the yeast pitch was (both under and over), and fermentation temperature. The higher the temperature, and abnormal pitch-rates stress the yeast, causing it to produce more (perhaps unwnated) flavours.

Some good rules of thumb - oxygenate your wort properly, pitch a proper amount of yeast, and keep temperatures on the cool side - especially for the first 72 hours.

Once the primary phase (the sometimes really bubbly bit) of fermentation is complete, the yeast is still working. Make sure you leave enough time for the yeast to do its job. Some undesirable compounds are normally created during fermentation. In the later stages, the yeast re-processes these compounds, removing these flavours from the beer - obviously if the yeast is removed or refridgerated, it never finishes this stage. Often allowing the beer to warm a little during this phase helps.

Just so there's some numbers here ~

• Use pure O2 for 90 seconds / 20 litres, or shake your fermenter vigorously to aerate the wort.
• Pitch a full packet of yeast, after rehydrating it. Or make a starter.
• Ferment ales between 17 & 20C, Lagers between 7 & 14C - at least for the first phase
• Allow the ferment to run to completion, at least a week, but 2 weeks wont hurt.

Getting a good fermentation is the key to making good beer. If you want a clean tasting beer, use an adequate pitch of POF negative yeast into a cool, aerated wort. Let the yeast do its job.

The most common ways I’ve come across to keep a beer (and perhaps ale specifically) free from yeast in suspension is to:

• mature the beer properly and let the yeast fall out of suspension due to inactivity (patience is king when making beer)
• use fresh yeast
• and if necessary cold crash the ale for a few days
• if neither of the above options suffices you can add a fining agent like gelatin and cold crash even more

If you’re reusing yeast from a previous batch be sure to wash the yeast. I don’t know of any practical filtering techniques for home brewers.

Gelatin is a great fining agent that will pull the yeast out of suspension, the taste of gelatin itself is absolutely undetectable in beer and the grocery store Knox unflavored gelatin will work just as well as anything you get from a homebrew store. Just be sure that your fermentation is complete before you start this.

Heat 1/2 to 3/4 cup of water to to 150-155F. Add 1/2 to 1 teaspoon of gelatin and stir to dissolve the gelatin. Add it to your fermenter, stir just a little bit, chill the fermenter and wait a day or so. Overnight usually seems to be plenty for me but I'm using a refrigerator. You should end up with brilliantly clear beer. at least on the lighter styles.