Trying to understand cold crashing.

Cold crashing cleans up more than the appearance of the beer. Dropping out the yeast and other particles in suspension removes a lot of the "bite" you get from beers that have a lot of residual yeast. Depending on the strain, the character of yeast in suspension can be anywhere from interesting and tasty to downright offensive.

One thing to be careful of - even though cold crashing cleans up a beer, letting it sit warm also cleans it up in different ways. As the yeast finish out fermentation and start to go night night, they absorb many compounds they can use as nutrient reserves when the next opportunity to become active arises. The most notable of these is diacetyl (butter flavor). Because of this phenomenon, you want to make sure you don't rush to cold crash the beer as soon as it approaches F.G. Patience will reward you.

 

Very well stated. I would also add that to truly remove most/all of the yeast, break material, and hop material, you must filter. Filtering is not nessessary for appearance sake. Cold crashing properly and for an appropriate amount of time serves the purpose well. It also leaves plenty enough yeast and nutrients in suspension, even if you can't see them, they are there, for bottle carbonating.

 

The cold crashing process expedites the clearing of beer. If you have patience, this clearing process will occur at non-cold temperatures. Time and gravity will clear any beer. I have some beers left for a Wit that I bottled in June 2012. That beer was cloudy (like a Wit should be) for a few months after bottling; those beers are crystal clear now. Those Wit beers are still real tasty; just not cloudy per style.

Cheers!