https://www.escarpmentlabs.com/single-p ... ast-craves
FAN is a significant nutrient for yeast. Too little can lead to stalled ferments, too much can lead to excess tails (Fusel alc/oils). FAN is a group of amino acids than yeast uses to build esters, sterols (used in cell walls) and other compounds. In whiskey it is created when the grain is in heated in the malting process or during a protein rest. Proteins and complex amino acids are broken down by proteolytic enzymes (peptidase and protease). If you're using a high malt mashbill you should be fine. If not DAP is a FAN nutrient.
http://howtobrew.com/book/section-3/how ... dification
http://blog.brewingwithbriess.com/under ... -analysis/
Significance: FAN is another analysis that can indicate the amount of free amino groups available to yeast during fermentation. This analysis is only performed on Base Malts. It has no significance in specialty malts.
Test: This test is a measurement of the free amino nitrogen content in a wort sample. The assay is typically run on an automated flow instrument. It involves the reaction of the sample under controlled temperatures with ninhydrin, a colored compound that changes incrementally with reaction to amino groups.
Ideally: A standard FAN value for most base malts is 180ppm and above.