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Apparent attenuation and Flocculation?

So I have been looking at recipes on the All-Grain Northern Brewer list. I cam a across two words I am no familiar with.

Flocculation. was the the first I looked up and found that it is all about how long the yeast stay active for example Low means it will stay in suspension longer so low flocculation will do their thing longer.

Apparent attenuation was the next term I was confuse on. What I found was amount of reduction and the temp at which the yeast should be.

So my questions are am I right? Is this that important to be thining about? Why do some recipes haf=ve this info and some do not?

That’s pretty much it. Flocculation is how much falls out of suspension when fermentation is nearing an end. Apparent Attenuation is the percentage of sugar that is converted to alcohol.

AFAIK, temp has nothing to do with AA.

You can use the AA% to figure out a ruff idea of where your Final Gravity should end up.

I am gathering that it is not something I should too overwhemed with at this point?

Exactly, it is going to do what it is going to do. Not much change will occur by worrying about it. Best thing you can do is give it time to do its thing.

2 things that I’ve never worried about.

I would be more concerned with finding the yeast and temp that produces to flavors you like. If that yeast doesn’t clear very well , cold crashing should get you a clearer beer.

If you cold crash can you still harvest the yeast?

Yes, definitely, it is just like refrigerating the yeast when it arrives from the store

apparent attenuation:

I brew a beer that measures 1.070 original gravity

After 3 weeks, the beer is at 1.015

(1.070-1.015) / .070 = 0.785, or 78.5% apparent attenuation (this is relatively HIGH AA). This is the degree to which the yeast have consumed the dissolves sugars in the wort.

Low ATTENUATING (ie below 70%) yeasts are better for beers whose style guidelines call for some residual sweetness that your tongue will perceive and your belly will digest since the yeast didnt.


its useful to think about this as a measure of how much yeast will settle once fermentation is complete. A high flocculating yeast will form a tightly packed yeast cake at the bottom of the fermenter and the beer on top of it will be clearer as it will have less suspended yeast in it.

low flocculation = cloudy

high flocculation = clear

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