Introduction to Ingredients
Mordern Beer is made from water, malt, hops and yeast. Sometimes we use adjuncts too. This section describes in more detail the basic ingredients that make quality beer!

Malt    Hops    Yeast    Water    Adjuncts

Ingredients: Malt
Reference:
* Briess Malting and Extract Process (PPT file: 7.5 MBs)
* Briess Malt & Ingredients Company 

Basics:
All beer is made from Malted grains. These grains are typically two- & six-row barley, but may include wheat, rye, crystallized, roasted, & specialty malts. In terms of Barley, a grain begins as a mature seed that is harvested at the proper time. The seed is composed of an endosperm & germ, surrounded by a husk. The endosperm is a complex carbohydrate: insoluble cellulose, soluble hemicellulose, starch & sugars.

Malting is the process of converting the hard starchy endosperm into fermentable sugars. This is done in two steps: malting & mashing. During malting, the protein & gum matrix surround the starch granules is broken down, allowing for greater permeability by water, & access to the starch by enzymes. In mashing these enzymes attack the starch granules - long chains of carbohydrates - & converts these into sugars by splitting them into smaller molecules.

To develop the enzymes important to mashing, the grain seed is germinated whereby it is soaked in water for a period in a controlled environment, producing a root or “awn” as the embryonic plant becomes awakened. The process is then arrested after a short duration of 3 to 10 days. Kilning follows for many variations, & the type & degree of kilning determines the level of enzymes produced as well as the flavor. The finished product is referred to as “Malt”.

Mashing:
Mashing is the process of steeping cracked malted grains in a solution of water for a period of time between 140° to 158°F until the starchy liquid is converted to sugar by enzymes. The enzymes are stored in the Malt until needed during mash. There are two versions of enzymes, each equally important to brewing: Alpha-amylase which breaks long chains of sugars into smaller chains, & Beta-amylase which breaks off two-sugar molecules as a time – called disaccharides, or maltose – the most common sugar produced from barley malt. Maltose is readily consumed by yeast to produce alcohol & carbon-dioxide. Groups of four or more sugar molecules are called dextrins, cannot be fermented by yeast, & are important for head retention & body.

Control over which types of sugars are produced is determined by the mash pH & the temperature. Alpha-amylase works best at higher range of temperatures whereas Beta-amylase works best at the lower range: A higher terminal gravity (greater mouthfeel) beer with lower alcohol is produced by mashing at higher temperatures whereas a lower gravity higher alcohol beer is produced at lower mash temperatures. Finding the right balance is key to a successful brew: the optimum temperature is about 149°F. The name for this period of conversion from starch to sugar is called a Saccharification Rest.

To determine if conversion has neared completion, test by withdrawing a tablespoon sample of liquid & place in a white coffee cup. A drop of Tincture of Iodine will turn black in the presence of starch, whereas there will be no color change if starch is not present.

Upon successful conversion, or saccharification, the grains are them gently rinsed with sparge water at about 168°F to arrest any further enzymic activity. The sweet liquid is extracted from the grains & drained off into the kettle for boiling & hop additions. Depending on the methods employed depends upon the style of beer to be brewed. Some brewers take the first runnings & produce a large beer such as a stock or old ale, barley wine, or strong ale. It is not uncommon to recycle the liquid prior to running off & divert it back on top of the grain bed which aids in clarifying the liquid. Some brewers employ continuous recirculation to achieve higher extract ratios from their mashes. Each method has its' merits, & owes much to the legacy of brewing.

Ingredients: Hops
Reference:

* Hopunion CBS LLC
* "Zymurgy - The Classic Guide to Hops (#767)" 

Hops (Humulus lupulus), more specifically – the female hop cones - are a required ingredient in all except specialty beers. They provide stability, bittering, flavor, aroma, and to a lesser extent appearance to beer. They are typically added during various but important stages of the wort boil. However additional benefits are achieved from dry-hopping in the barrel (Ref: IPA).

Composition:
Hop cones are mostly cellulose & protein compounds, the latter of which may aid in head retention during boil. Up to 20% of tannins may come from the hop (strig & bracts), contribute slightly to the darkening of wort, & combine with complex proteins that aids in the break formation in the kettle.

But the most important features of hops are the hop resins & essential oils that are derived from the lupulin glands found on the bracts & bracteole. Hop resins are characterized as Soft Resins & Hard Resins. Soft resins contain Alpha & Beta Acids, & uncharacterized soft resins. Alpha Acids are: Humulone, Cohumulone, & Adhumulone. These are the largest contributors to bittering from isomerization during the boil, particularly the Cohumulone as it tends to be harsh at higher levels.

Essential Oils contain oxygen-free hydrocarbons, oxygenated products, & sulfur-containing compounds. Hydrocarbons are highly volatile, aromatic, and account for 80% of hop oil, key of which are myrcene & humulene, though other compounds play in favorably as well. They are best utilized as late kettle additions or in dry-hopping. Myrcene is present in higher quantities with bittering hops and contributes the pungent character, but with oxidation – degrades to floral/flowery, & lending to citrus/piney expressions as well. Humulene varies inversely to Myrcene in that it’s more delicate and found in higher quantities in aroma hops. Oxidation of Humulene contributes in flavor & aroma as herbal or spicy. A small group of sulfur-containing hydrocarbons also exists, the most significant is polysulfides which is associated with unpleasant aromas & flavors such as cooked vegetables, skunky, rubbery & sulfury.

Hops come in three basic forms: whole leaf, oil, plugs & pellets, all but the first allow for mechanized production & extended storage with some minor drawbacks to packaging.

Boiling hops for long periods imparts bittering. However, hop flavor & aroma is achieve by boiling from 2 to 30 minutes, steeping through a hopback or grant, or dry-hopping. Consistency in flavor/aroma is difficult given the variances from year-to-year as well as supplier, & from bail to bail.

Bittering value of hops is measured as “Bittering Units”; homebrewers use IBU’s – International Bittering Units. This is inexact however for the perceived bittering varies from the measured bittering due in large part to the subjectiveness of the human condition & the physical aspects of process, storage & aging.

Ingredients: Yeast
Yeast is a name applied specifically to a certain group of microscopic fungi & to commercial products consisting of masses of dried yeast cells or of yeast mixed with a starchy material & pressed into yeast cakes, or as part of a yeasty matrix in combination with nutrients in liquid form. Although a number of fungi are sometimes called yeasts, the true yeasts are unicellular, consist of oval or round cells, & reproduce chiefly by budding. Under certain conditions some yeast cells secrete a thickened wall, & the cytoplasm of the single cell within divides to form four or eight cells, or spores, known as ascospores, which emerge when the wall ruptures. In a few species two cells fuse before undergoing spore formation. There are about 500 species in all.

Yeasts, especially those of the genus Saccharomyces, have long been of commercial importance because they are the chief agents in alcoholic fermentation. Because of this they are essential to the making of beer, wine, & other alcoholic beverages & industrial alcohol. Wild yeasts, those found in nature & probably carried by insects from the soil to fruits, are frequently active in the fermentation process. In bread making the yeasts act upon the carbohydrates in the dough, forming carbon dioxide & ethyl alcohol, which are driven off in the baking process; the escaping carbon dioxide causes the bread to rise. Since early times yeast has been used in treating various ailments; brewer’s yeast has a high content of thiamine & other vitamins of the B-complex group. Yeasts are classified in the kingdom Fungi, phyla (divisions) Ascomycota & Basidiomycota.

Basically, yeast has three phases in their lifecycle:

1. Respiration phase: The yeast consume oxygen & sugar in order to reproduce. The by-product of this is CO2 (but no alcohol).
2. Fermentation phase: The yeast consume sugar anaerobically. The by-product of this is CO2 & alcohol.
3. Flocculation: The yeast give up the ghost & clump together, either sinking to the bottom or rising to the surface (depending on the strain). 

All of these phases are happening at all times, but in a closed system like when you are making beer, most of the yeast will be coordinated.

Phase 1 can continue as long as there is oxygen & sugar available (although, see below). If oxygen runs out, phase 2 begins. If sugar runs out, phase 3 begins. Yeast will also replicate to a maximum density in the water assuming there is enough O2 & sugar & various nutrients to keep the yeast population optimal.

Once the O2 runs out, phase 2 begins. This produces alcohol. Yeast will also reproduce in this stage, but at reduced rates (it takes more sugar to produce enough energy to reproduce anaerobically). There are also many other by-products of fermentation (most of which are toxic to yeast). Once the sugar runs out, the yeast will move on to phase 3. Also, if the concentration of fermentation by-products reaches a certain level, the yeast will also move to phase 3 (the amount of tolerance is dependent upon the strain of the yeast). Finally, if there are not enough other nutrients in the water, the yeast will flocculate.

Finally, stage 3. The yeast leave suspension & either sink to the bottom or float to the surface (actually, all strains will do both, but the tendency to do one or the other is dependent upon the strain). Much of the yeast is still viable as long as conditions are restored to favorable levels.

Additional suggested reading: Zymurgy - The Magic of Yeast (#768)"

Ingredients: Water
Required Reading: BJCP
Additional suggested reading:

* "Principles of Brewing Science" By George Fix
* Zymurgy - The Great Grain Issue (#765)" 

Ingredients: Adjuncts
Required Reading: Beer Adjuncts
Additional suggested reading: Zymurgy - The Great Grain Issue (#765)"