FATTY ACIDS - A group of carboxylic acids, all of which impart a foul, soapy flavor to beer, contribute to its staling and affect its head retention.
FERMENTATION - The chemical conversion of fermentable sugars into ethyl alcohol and carbon dioxide gas, through the action of yeast resulting in a drop in the density.
FINAL DEGREE OF ATTENUATION - The maximum apparent attenuation attainable by a particular wort.
FINES - The finely crushed, flour-like portion of the draft.
FINING - A clarifying process that adds organic or mineral settling agents during boiling of wort and conditioning to precipitate colloidal matter through coagulation or adsorption.
FINISH - The long-lingering aftertaste of a beer, usually dominated by a balance between malty sweetness and hops aromas. The less malty the finish, the "drier" is the beer.
FINISHING HOPS - Hops added to the wort near the end of the boiling to impart hop aroma and character to the beer as opposed to bittering hops that contribute to its bitterness and are added during the boil.
FLASH PASTEURIZATION - Flash pasteurization is the heat treatment of beer in bulk for subsequent packaging.
FLAVOR STABILITY - The ability of a beer to retain the quality it had when it was bottled until it is consumed.
FLOCCULATION - The phenomenon by which yeast cells aggregate into masses toward the end of the fermentation process.
FOAM STABILITY - Measured as rate of foam collapse in freshly poured beer under controlled conditions.
FRUCTOSE - A highly fermentable monosaccharide that occurs naturally in malt typically making up from 1 to 2% of wort carbohydrates.
FUNGICIDE - An agent that kills fungi (molds).
FUSEL ALCOHOLS - Alcohols of high boiling point then ethanol, which are derived from keto-acids during the yeast protein synthesis. The formation of higher alcohols varies with yeast strain and yeast growth, fermentation temperature (an increase in temperature is followed by an increase in the formation of alcohols), and fermentation method. Fusel alcohols impart a harsh, clinging bitterness and are produced through the metabolism of amino acids. They are also referred to as higher alcohols.