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View Full Version : DAP/YAN and yeast hulls



Tiwas
04-07-2011, 04:32 AM
Ok, I've tried reading this stuff, but between switching programs to hide the fact that I'm on forums instead of working, and having people asking me to do what I'm paid for (wtf is up with that?? :P ), I'm having a little problem with my comprehension...

Sooo...This is what I think I've understodd so far.
1. Adding DAP helps increase YAN. Nitrogen is important for the fermentation, but how do I know how much YAN I have and how much DAP to add? As far as I can see, too much YAN is as bad as too little.
2. Yeast hulls are boiled (dead) yeast. I was under the impression that these would function as nutrient, but...from what I just read on the net, these supposedly binds to free fatty acids which helps the yeast eat more sugar. Is this right? If so, what's the connection here?

Cheers!

tycoon
04-07-2011, 08:58 AM
If you do a search for "nutrient", "YAN", etc, there are several interesting threads about this. E.g. this one by Medsen Fey http://www.gotmead.com/forum/showthread.php?t=12732&highlight=yan+content

wayneb
04-07-2011, 10:27 AM
And to address your second question, there is some YAN availability from yeast hulls, although the concentration of amino nitrogen available to the yeast from an addition of hulls is relatively small. Of more importance is the ability of autolyzed yeast cell walls to bind with several different chemicals that are toxic to living yeast. Then the hulls settle out of suspension, dragging those toxins with them down to the lees layer, leaving behind a healthier environment for those remaining living cells.