Mash ingredients
Mash ingredients, mash bill, mashbill, or grain bill are the materials that brewers use to produce the wort that they then ferment into alcohol. Mashing is the act of creating and extracting fermentable and non-fermentable sugars and flavor components from grain by steeping it in hot water, and then letting it rest at specific temperature ranges to activate naturally occurring enzymes in the grain that convert starches to sugars. The sugars separate from the mash ingredients, and then yeast in the brewing process converts them to alcohol and other fermentation products.
A typical primary mash ingredient is grain that has been malted. Modern-day malt recipes generally consist of a large percentage of a light malt and, optionally, smaller percentages of more flavorful or highly colored types of malt. The former is called "base malt"; the latter is known as "specialty malts".
The grain bill of a beer or whisky may vary widely in the number and proportion of ingredients. For example, in beer-making, a simple pale ale might contain a single malted grain, while a complex porter may contain a dozen or more ingredients. In whisky production, Bourbon uses a mash made primarily from maize, and single malt Scotch exclusively uses malted barley.
Variables
Each particular ingredient has its own flavor that contributes to the final character of the beverage. In addition, different ingredients carry other characteristics, not directly relating to the flavor, which may dictate some of the choices made in brewing: nitrogen content, diastatic power, color, modification, and conversion.Nitrogen content
The nitrogen content of a grain relates to the mass fraction of the grain that is made up of protein, and is usually expressed as a percentage; this fraction is further refined by distinguishing what fraction of the protein is water-soluble, also usually expressed as a percentage; 40% is typical for most beermaking grains. Generally, brewers favor lower-nitrogen grains, while distillers favor high-nitrogen grains.In most beermaking, an average nitrogen content in the grains of at most 10% is sought; higher protein content, especially the presence of high-mass proteins, causes "chill haze", a cloudy visual quality to the beer. However, this is mostly a cosmetic desire dating from the mass production of glassware for presenting serving beverages; traditional styles such as sahti, saison, and bière de garde, as well as several Belgian styles, make no special effort to create a clear product. The quantity of high-mass proteins can be reduced during the mash by making use of a protease rest.
In Britain, preferred brewers' grains are often obtained from winter harvests and grown in low-nitrogen soil; in central Europe, no special changes are made for the grain-growing conditions and multi-step decoction mashing is favored instead.
Distillers, by contrast, are not as constrained by the amount of protein in their mash as the non-volatile nature of proteins means that none is included in the final distilled product. Therefore, distillers seek out higher-nitrogen grains to ensure a more efficiently made product. Higher-protein grains generally have more diastatic power.
Diastatic power
Diastatic power, also called the "diastatic activity" or "enzymatic power", is a property of malts that refers to the malt's ability to break down starches into simpler fermentable sugars during the mashing process. Germination produces a number of enzymes, such as amylase, that can convert the starch naturally present in barley and other grains into sugar. The mashing process activates these enzymes by soaking the grain in water at a controlled temperature.In general, the hotter a grain is kilned, the less its diastatic activity. As a consequence, only lightly colored grains can be used as base malts, with Munich malt being the darkest base malt generally available.
Diastatic activity can also be provided by diastatic malt extract or by inclusion of separately-prepared brewing enzymes.
Diastatic power for a grain is measured in degrees Lintner ; or in Europe by Windisch-Kolbach units. The two measures are related by
A malt with enough power to self-convert has a diastatic power near 35 °Lintner. Until recently, the most active, so-called "hottest", malts currently available were American six-row pale barley malts, which have a diastatic power of up to 160 °Lintner. Wheat malts have begun to appear on the market with diastatic power of up to 200 °Lintner. Although with the huskless wheat being somewhat difficult to work with, this is usually used in conjunction with barley, or as an addition to add high diastatic power to a mash.
Color
In brewing, the color of a grain or product is evaluated by the Standard Reference Method, Lovibond, American Society of Brewing Chemists or European Brewery Convention standards. While SRM and ASBC originate in North America and EBC in Europe, all three systems can be found in use throughout the world; degrees Lovibond has fallen out of industry use but has remained in use in homebrewing circles as the easiest to implement without a spectrophotometer. The darkness of grains range from as light as less than 2 SRM/4 EBC for Pilsener malt to as dark as 700 SRM/1600 EBC for black malt and roasted barley.Modification
The quality of starches in a grain is variable with the strain of grain used and its growing conditions. "Modification" refers specifically to the extent to which starch molecules in the grain consist of simple chains of starch molecules versus branched chains; a fully modified grain contains only simple-chain starch molecules. A grain that is not fully modified requires mashing in multiple steps rather than at simply one temperature as the starches must be de-branched before amylase can work on them. One indicator of the degree of modification of a grain is that grain's Nitrogen ratio; that is, the amount of soluble Nitrogen in a grain vs. the total amount of Nitrogen. This number is also referred to as the "Kolbach Index" and a malt with a Kolbach index between 36% and 42% is considered a malt that is highly modified and suitable for single infusion mashing. Maltsters use the length of the acrospire vs. the length of the grain to determine when the appropriate degree of modification has been reached before drying or kilning.Conversion
Conversion is the extent to which starches in the grain have been enzymatically broken down into sugars. A caramel or crystal malt is fully converted before it goes into the mash; most malted grains have little conversion; unmalted grains, meanwhile, have little or no conversion. Unconverted starch becomes sugar during the last steps of mashing, through the action of alpha and beta amylases.Malts
The oldest and most predominant ingredient in brewing is barley, which has been used in beer-making for thousands of years. Modern brewing predominantly uses malted barley for its enzymatic power, but ancient Babylonian recipes indicate that without the ability to malt grain in a controlled fashion, baked bread was simply soaked in water.Malted barley dried at a sufficiently low temperature contains enzymes such as amylase, which convert starch into sugar. Therefore, sugars can be extracted from the barley's own starches simply by soaking the grain in water at a controlled temperature; this is mashing.