This a string is a little old, but it caught my interest. Excessive FAN is seen as a problem, but it's not so much a problem with Continental malt. The FAN level is directly correlated to protein content.
- Fan levels are reduced by yeast growth, the reduction of FAN from pitch to maximum yeast density is directly corelated. So overall growth of biomass will reduce the final FAN level. Higher levels of wort aeration can reduce the final FAN levels by promoting a higher biomass growth, more yeast growth = less FAN in beer.
- Breweries that use European malt have more of a problem with not enough FAN due to lower levels of protein, where as North American has a greater amount of protein and excessive FAN is a problem. The use of adjuncts reduces FAN levels.
- North America barley crop standards allow for more protein, up to 11-12%. This allows farmers to use more nitrogen fertilizer to increase crop yields, European yields per acre are lower and this drives the cost of barley up.
Is FAN a big problem for most brewers? Depends on the malt and yeast growth.
Here's a really interesting podcast with Joe Hertrich about malt and how North American 2 row malt came to overtake 6 row.https://www.masterbrewerspodcast.com/088