Ingredients: Grain (3 of 3)

While many styles of beer are made using only water, malted barley, hops, and yeast, some beer styles use grains other than malted barley. 

Anything other than malted barley that is incorporated into beer brewing is called an adjunct.

Because unmalted grains have not had their starches converted into sugar, these grains must be cooked to put the starches into a form that can be converted into sugar by the barley malt's enzymes. The technical term for this cooking is gelatinization.

The temperatures required to gelatinize the starches in adjunct grains are high enough to break down the barley malt's enzymes, so adjunct grains are cooked separately prior to being mixed with the majority of the barley malt. This precooking is often done with hot water in what is called a cereal mash. 

Adjunct starches may also be gelatized by passing wet grain between hot metal rollers (think of instant oatmeal) or by heating the grain with hot air (think of popcorn), but this increases the cost of the adjunct grains and these pre-cooked grains are usually used by homebrewers, who pay for the convenience of not having to do a separate cereal mash.

Each type of adjunct grain provides it's own contribution to the finished beer.  

Wheat is used in both malted and unmalted forms. It contributes to a large, white foamy head and adds a distinct grain flavor and vaguely citric sweetness. 

Oats create a dense head of foam and add unfermentable components that create a smooth, silky mouthfeel. Oatmeal Stout is a good example.

Rye has an earthy, black pepper spiciness.

Specialty Grains

Barley malt that has been kilned to the point that it no longer contains enzymes or fermentable sugars is called specialty malt. It is added to contribute color and caramelized sugars, which are unfermentable.

These specialty grains are steeped in hot water (much like making tea) in order to leach out the unfermentable sugars that contribute body, color, and flavor to the beer. 

The Special Case of Corn and Rice

In the 19th Century North America, farmers grew six-row barley because it was well adapted to North America's climate, and because six-row barley yielded more grain per acre than two-row barley.

In 1840, Bavarian lager yeast was brought to America. When German brewers attempted to create German-style lagers using six-row barley, the high protein levels created a fuller bodied beer that became hazy.

Brewing scientist Anton Schwartz found that substituting corn or rice for a small portion of the six-row malt lowered the proportion of protein, resulting in a beer that was lighter colored, lighter bodied, and stayed clear and bright. 

After Prohibition ended, brewers began to see corn and rice as cost cutting tools. Corn and rice were cheaper than barley, and six-row barley was cheaper than two-row barley.

Corn lightens the color and body of beer while imparting some residual sweetness.

Rice has a more neutral flavor than corn and imparts a recognizable dryness to the beer.


Beer Styles Using Corn and Rice
 
British Pale Ales (also known as Bitters) may use adjunct sugar, corn, or wheat.

Cream Ale uses up to 20% corn, while Premium American Lagers may use up to 25% corn and/or rice.

The use of corn and rice adjuncts is most commonly associated with Standard American Lagers and Lite American Lagers, which use up to 40% adjunct ingredients.

The Takeaway:

• Barley is the primary grain used in beer. 
• Malting the barley activates enzymes that convert starches into sugars. 
• Kilning the malted barley develops a variety of malt flavors.
• Grains other than barley can be used in brewing, but they must be cooked before barley's enzymes can break down their starches.

For further research:
How to Identify Adjunct Grains in Your Beer