Oxygenation and Clarity

[Tom C]

Since I started using pure oxygen and a stone to oxygenate my wort prior to pitching yeast I have failed to achieve good clarity in the finished beer.  This also appears to be the case with a couple of fellow brewers and is the only common change in process that is concurrent with this drop in clarity. 

We all manage bright / clear wort into the fermenter, have used a variety of ale and lager yeasts which ferment well and the finished beer tastes fine.  So I'm wondering if anyone can shed light on the idea that additional oxygen at the start of a fermentation would alter the yeast's flocculation as it doesn't appear to be any other problem.

[oliver]

Interesting, I've been using pure O2 for about 8 months now and haven't had any clarity issues. Are you sure you haven't changed anything else? Are you comparing the exact same recipe, ingredients and process? Just had a quick scan of the O2 chapter in the yeast book, no mention of clarity issues due to O2 levels.

What type of haze are you getting? I'm assuming it's yeast staying in suspension?

One thing that comes to mind is water, if you're using water from the tap it could be that it's started coming from a different source? Also, you probably already know but you want at least 50ppm calcium in your final water profile for yeast health + flocculation.

Could also be yeast management - are you pitching lots of clean, fresh, healthy yeast in all these beers?

Also have you been cleaning your stone regularly? I get a bit lazy with mine :p

How long are you lagering your lagers for? Having lager yeast staying in suspension is probably not a bad thing - unless it's been more than 2 or 3 months at lager temps...

Sorry can't think of anything else right now, you could try rebrewing the same recipe multiple times with different O2 levels and see what happens. Or split a batch between two fermenters - give one the O2, shake the other and pitch the exact same yeast in both.

Good luck :)

[Ralph]

Are you sure it is yeast haze? If yeast haze it should eventually clear over time. If something else like polyphenols then it is usually the mash/lauter or amount of hops added that will cause the haze.

What specific strains of yeast are you using?

Are the fermentations going to completion more quickly than before you were adding O2? Or is the ferment taking the same or longer than it used to?

Does the yeast have enough nutrients to grow quickly with the O2? Are you adding a yeast nutrient? 

By the way I dont consider bright wort into the fermentor to be essential to getting bright beer out of the fermentor. Some cold break in the fermentor can help the fermentation (nutrients etc) and will generally sit down in the trub pretty quickly once the ferment has finished.

[Tom C]

Pretty sure it's yeast as the initial wort is clear of suspended particles, and the haze is very fine as you'd expect with yeast in suspension.  It also slowly clears, although never completely by the time a keg empties!

The yeasts are a variety - British, Thames Valley, American, Kolsch, Irish... and the pitch is well started on a stirplate.  Fermentations are healthy and slightly faster than pre-oxygen.

I hadn't thought of adding extra nutrients to compliment the oxygen, that may help them complete their lifecycle.

Any thoughts on using dried or bread yeast late in the boil (to kill and break down the cells) as a source of nutrient?

[oliver]

I add 1/2 tsp of the whitelabs nutrient to every brew, whole tsp for strong beers. Seems pricey but it actually goes a long way. Make sure you've got enough calcium in your water too.

Another thing that comes to mind is pH - are you regulating your mash pH?

Just found this: http://www.wyeastlab.com/hb_clarification.cfm which mentions various factors and their effects on flocculation.

Also are you using kettle finings?

[Tom C]

Thanks mate, I'll give the nutrient a try.

I'm usually adding Calcium Sulphate to the water and always 5.2 stabiliser in the mash and Koppafloc at the end of the boil.

Maybe I should let it condition longer in the keg, I find the unprimed riggers I keep for the handpump tend to drop clear quicker - no CO2 to churn it up?

[oliver]

Yeh you might be right on the CO2 churn. If you want to speed things up in the keg you could gelatine fine it once its cold and carbed, give the gelatin a good 3 days to do its thing, then pull off a couple of cloudy pints, the rest should be really clear. Good luck

[Matt Smith]

What temp are your riggers? If they're kept at cellar temp and your kegs are at fridge temp then id assume you have a protein/chill haze rather than a yeast haze.

[Matt Smith]

Especially so given that yeast will always drop faster in cold temps than warmer temps

[Ralph]

Yep. I always chuck a bit of yeast nutrient into each brew too. I would be more inclined to buy a specific yeast nutrient than try adding old/bakers yeast into the boil. Places like brewshop sell nutrient. 

[Peter Smith]

+1. For wyeast nutrient

I have found since kegging I have had much cloudier beer. Putting it down to co2 churn while I bed system in.

[Grant R Baker]

I found the same... but the run clear eventually. The gelatine method works for me if I want the beer crystal clear quickly.

[Tom C]

Thanks for the tips.

Exhaustive testing of cold beer, warm beer, and cold beer as it warms have eliminated chill haze.

Wyeast have this to say:

• Poor or low wort aeration can result in early and incomplete flocculation
• Adequate aeration can result in delayed and more intense flocculation
• Affects sterol and fatty acid synthesis and presumably cell surface hydrophobicity (CSH)

So I'm going to guess I have 'delayed' flocculation which may become intense!  In the meantime I'll use nutrients to help the little fellows along and if I'm still picky (or drinking too early) I'll give the gelatine a run.