FAN - the measure of Free Amino Nitrogen available to the yeast in the wort for nutrition during fermentation. Without sufficient FAN the yeast are less efficient and produce more off-flavor by-products. Corn, rice,and cane sugar don't contain FAN, so using large amounts of these products deprives the yeast of needed nutrients. It's usually better to add more malt to boost gravity and increse FAN.
Fermentation - the total conversion of malt sugars (saccharides) to beer, consisting of three phases: adaptive phase (the first few hours during which the yeast adapts to its new food source and environment); primary or attenuative phase (usually within 12 to 24 hours and lasting a few days during which the yeast converts most of the fermentable sugars in the wort); and secondary or conditioning phase (final weeks during which the yeast consume remaining fermentable sugars and reduce primary phase yeast by-products such as diacetyl and acetaldyhide. See Bottom Fermentation, Top Fermentation, and Yeast.
FG - final gravity describes the concentration of sugars in the wort after fermentation, reflecting the attenuation of the fermentation, ie., the degree of conversion of sugars or saccharides by the yeast to ethanol and carbon dioxide during fermentation. A lower final gravity indicates a dry or crisp flavor, while a higher final gravity indicates a sweet or malty flavor. Subtracting the FG from the OG gives the approximate ABV of the beer, following this formula: (OG - FG) x 131.25 = ABV%.
Finishing Hops - hops known for good aroma and flavor are added about 5 to 10 minutes to end of boil or at knockout so that fewer of the aromatic and flavor oils are lost to isomerization or evaporization, contributing the characteristic hop flavors and aroma, with minimal influence on the bittering. See Aroma Hops, Bittering Hops, Flavoring Hops, Dry-Hopping.
Flavoring Hops - hops known for good aroma and flavor are added about 20 to 30 minutes before the end of boil. Flavoring hops make a compromise between alpha acid isomerization and evaporization of the aromatics to yield moderate bitterness addition and hop flavorings. Many hop varieties may be used as desired. See Aroma Hops, Bittering Hops, Finishing Hops, Dry-Hopping.
Flocculation - describes how fast or how well yeast clumps together and settles to the bottom of the fermenter after fermentation is complete. Different yeast strains clump differently and settle faster or slower. See Flocculant.
Gravity - (ie. specific gravity) like density, gravity (in the context of brewing) describes the concentration of malt sugar (saccharides) in the wort. The specific gravity of water is 1.000 at 59F. Typical beer worts range from 1.040 to 1.080 or greater. See Boil Gravity.
Hops - Hops are the flowers (also called seed cones or strobiles) of the hop plant Humulus lupulus. They are used primarily as a bittering, flavoring and stability agent in beer, to which they, beyond bitterness, impart floral, fruity or citrusy flavours and aroma. See Bittering Hops, Flavoring Hops, Aroma Hops, Finishing Hops, Dry Hopping, Lupulin Gland, Alpha Acid, IBU, Hop Profiles, and Calculating IBUs.
Hopback - right after knockout, the hot wort is run through a small chamber full of fresh hops before the wort enters a chiller. Noble hop varieties are best for this step for fine hop aroma and flavor. A side benefit of hopbacking is the added filtration of suspended trub in the wort. An alternative is dry-hopping.
Hydrolysis - cleavage of chemical bonds by the addition of water, eg., when carbohydrates or starches are broken down into their component sugar molecules (saccharides) by hydrolysis. This process is also called saccharification. See Hydrolytic Enzymes and Mash.
Hydrolytic Enzymes - enzymes, catalytic proteins, that use water to breakdown substrates--in brewing, breaking down starches within the seed (endosperm) into fermentable sugars (saccharides). See Amylase, Hydrolysis.
Hydrometer - measures specific gravity of liquid, used in brewing to measure difference between gravity of pure water and water with dissolved sugars (saccharides) and to determine progress of
Hydrometer Jar - 1.25" diameter plastic tube, 12" tall with large flat bottom for taking hydrometer measurements.
IBU - International Bittering Units, measures the bitterness contributed to beer from the addition of hops, taking into account AAU, recipe volume, boil gravity, and boil time. See Calculating IBUs and Tinseth.
Ion - an atom or molecule with a non-zero net electrical charge (its total number of electrons is not equal to its total number of protons) due to the loss or gain of one or more electrons. A cation is a positively-charged ion, while an anion is negatively charged.
Isomerization - the process by which one molecule is transformed into another molecule which has exactly the same atoms, but the atoms have a different arrangement e.g. A-B-C → B-A-C (these related molecules are known as isomers). In brewing, during the boil, with heat applied, the alpha acid compounds found naturally in hop resins isomerize to allow solubility in water to contribute their characteristic flavors and bitterness.