Unit 1: Malted Barley

Question 1

Why can’t raw barley be used directly and immediately during brewing?

Answer 1

The starches contained in barley are inaccessible in the raw kernel. They are protected by a dense matrix of proteins and surrounded by rigid cell walls. A hard husk surrounds them, and the starch itself is too complex for yeast to act upon.

Question 2

What are the three stages of malting?

Answer 2

1) Steeping
2) Germination
3) Kilning or Drying

Question 3

What happens during steeping?

Answer 3

The barley is submerged in water several times for 2 or 3 days. This hydration causes the moisture content of the barley to rise from about 12% to about 45%. This phase also includes periods of aeration. Together, these stimulate the biochemical processes that will initiate the growth of a new barley plant in each kernel.

Question 4

What happens during the germination phase?

Answer 4

The barley is removed from the steep water and kept moist for 3-5 days. During this time the moist barley is turned mechanically to keep developing roots from matting together.

Question 5

What biochemical changes happen during germination?

Answer 5

The water activates enzymes that lie naturally in the grain. During the germination of barley seeds under standard conditions, an active complex of enzymes amylases (α- and β-amylases), proteases, cytases, and oxidoreductases are formed, which dissolve endosperm cells and convert reserve substances into soluble compounds. (These same enzymes will further act upon the starches later during the mashing process.) The water also activates hormones that will start the growth of the new plant. The kernels begin to develop rootlets (called chits), and a new barley plant begins to form.

Question 6

Where in the barley kernel are the enzymes produced?

Answer 6

During germination, hormones are sent to the aleurone layer surrounding the endosperm, which produces the enzymes. The aleurone layer is the enzyme ‘factory’ of the barley kernel.

Question 7

What enzymes are created in the aleurone layer during malting?

Answer 7

1 Amaylses -

Alpha-amylase breaks down large, complex, insoluble starch molecules into smaller, soluble molecules for the beta-amylase.

Beta-amylase is capable of breaking down starches and creating soluble sugars. After the alpha-amylase enzymes create smaller soluble molecules, the beta-amylase enzymes create the most fermentable sugars by breaking down starch to create maltose and glucose.

2 Proteases

Proteases break down large proteins into smaller ones. This is important in brewing because brewers are concerned with the nitrogen content of their beer. Yeasts, necessary for brewing beer, use nitrogen as a primary nutrient. Nitrogen is found in all proteins, but yeasts prefer free nitrogen. Proteases are critical for cleaving proteins and providing that free nitrogen to yeast.

3 Cellulases

Cellulase is an enzyme family that catalyzes the breakdown of cellulose. Cellulose is mainly found in plant cell walls.

4 Lipases

Lipase, present in the grain of rice and barley, catalyzes the hydrolysis of triacylglycerides at a lipid-water interface to yield free fatty acids (FFA). In brewing, FFA is generally associated with negative effects, including the formation of stale/off-flavor aldehydes.

Question 8

What is malt modification?

Answer 8

The changes that occur in making barley into malt is collectively called modification. Modification refers to the extent to which the endosperm breaks down. Enzymes gradually convert the rock-hard endosperms into a soft, chalky form. The degree of modification of any malt results from germination time and temperature.

Question 9

What is a highly modified malt?

Answer 9

Well-modified malts mean types of malt that the brewer can easily extract the sugars during mashing. Under-modified malts require the brewer to use more time and techniques to extract the sugars.

Highly modified means that the malt has a very high level of enzymes that have broken down cell walls and softened the starches in the endosperm.

Question 10

In malting, what is the acrospire?

Answer 10

Acrospire is the sprout of a grain seed, the beginning of a new plant. In the field, after the snow has melted and the moist soil is warmed by the spring sun, the acrospire grows in a spiral from one end of the seed—hence its name of acro“spire”—while rootlets develop at the other end.

Question 11

At what point in the development of the acrospire does the maltster consider the grain to have been fully modified?

Answer 11

One traditional measure of modification is the length of the acrospire. Generally, the growth of the seedling is allowed to progress until the acrospire is just over three-fourths of the length of the grain. At this point, the acrospire is considered fully modified. Longer or shorter or longer acrospire lengths are referred to as “over” and “under” modified malts, respectively.

Question 12

What is ‘green malt?’

Answer 12

Germinated malt that is ready for drying/kilning.

Question 13

What are the four goals of the kilning process?

Answer 13

1) Reduce the moisture content to around 4% to facilitate long-term storage
2) Preserve barley enzymes that will be needed later in the brewing process
3) Drive off dimethyl sulfide and other undesireable and volatile flavor compounds
4) Produce a variety of flavors and colors due to various degrees of roasting and processing

Question 14

Which enzymatic processes happen in germination, and which happen later in mashing?

Answer 14

In germination, the grain’s endosperm is modified: its cell walls and proteins get broken down, enzymes are produced, and starch becomes accessible.

The starches will be broken down by the enzymes and converted into fermentable sugars in mashing.

Question 15

What happens in the first drying stage of kilning?

Answer 15

The green malt is loaded onto the perforated floors of the kiln. Fans drive heated air through the floor at lower temperatures (122-140F) to reduce the grain moisture. Lower temperatures minimize the destruction of the enzymes needed later in mashing to convert starches to simple sugars. The target moisture content is about 5%.

Key point: As the water level is lowered, the enzymes become more resistant to the effects of heat

Question 16

What happens in the curing stage of kilning?

Answer 16

Further treatment at higher temperatures and longer times produces a wonderful palette of flavors that enhance beer. The problem is that more heat and time results in less and less enzyme survival.

Base malts are kiln-dried, typically with a 180-190° F finishing heat for 2-4 hours. This develops flavors ranging from very light malty to subtle malty.

Specialty malts are dried in a kiln at higher temperatures for longer periods of time, roasted, or both. Varying moisture levels, drying time, and temperature develop each specialty malt’s flavor and color characteristics.

Question 17

What is ‘diastatic power’ in dried malts?

Answer 17

Diastatic power refers to the enzymatic power of the malt—the malt’s ability to break down starches into simpler fermentable sugars during the mashing process. For example, a 6-Row base malt has a higher diastatic power than a 2-Row base malt.

Question 18

What is the scale used to measure diastatic power?

Answer 18

The scale used to measure the diastatic power of a grain is the Lintner scale. The symbol that is used to denote Lintner is °L. Yes, this is the same symbol that we use for the Lovibond color scale so confusion between them is common.

Question 19

Which malts are considered base malts?

Answer 19

Base malts are those with higher diastatic power and tend to be light in color.

Pilsner - cured at a maximum temperature of 185F, very light color such as <2°L (Lovibond), produces flavors of water cracker or white bread, diastatic power of 75-140°L (Lintner)

Two-row Pale Malt - cured at a maximum temperature of 220F, light color such as 2 to 4°L (Lovibond), produces flavors of biscuit, graham cracker or light toast, diastatic power of 50-150°L (Lintner)

Six-row Pale Malt - cured at a maximum temperature of 220F, light color such as 2 to 4°L (Lovibond), produces flavors of biscuit, graham cracker, or light toast, diastatic power of 160°L (Lintner).

Vienna Malt - cured at a maximum temperature of 220F but for a much longer time, light color such as 3-4°L (Lovibond), produces flavors of toast, pretzel, or bread crust, diastatic power of 50-80°L (Lintner).

Munich Malt - darkest of the base malts, cured at a maximum temperature of 220F but for a much longer time, amber to brown color such as 10°L (Lovibond), produces flavors of toast, pretzel, or bread crust, diastatic power of 25-75°L (Lintner).

Wheat Malt - can be cured at a lower temperature than barley, temperature of 176-185F, light color such as 2 to 8°L (Lovibond), produces flavors of flour or uncooked bread dough, diastatic power of 60-170°L (Lintner).
Wheat malt has higher protein than barley for more body and better foam stability. Wheat also lacks a husk, so it will not produce a filter bed during lautering.

Question 20

The highest diastatic power comes from which malts, and what would be the range of their Lintner scale?

Answer 20

The best base malts (often called pale malts) would be pilsner malt, 2-row, and 6-row barley, measured in the 140-160°L.

Question 21

Which malts would have the lowest diastatic power?

Answer 21

The darkest malts, especially black patent malt and crystal and caramel malts, have diastatic power at or nearly 0°L. These are added purely for their flavors and colors, with no expectation that they will contribute any enzymes. The starches they contain will be converted to sugars by the enzymes contained in the base malt.

Question 22

What’s different about caramel and crystal malts?

Answer 22

Crystal malt, also called caramel malt, reflects the color and flavor it adds to beer. Some purists distinguish between the two terms, pointing out that British crystal malts are produced in a roaster, while caramel malts may be made in a roaster or a kiln.

They are produced separately from pale malts. They are typically made from high nitrogen barley, first soaked in water and then germinated.

Where regular pale malt is next dried and kilned at low temperature, caramel, and crystal malts are left wet and heated to typical mash temperatures of 150-170 F (66-77 C) for a few hours at high humidity. This effectively “mashes” or converts the sugars while they are still in the grain. Caramel malt is then roasted at a higher temperature of around 250F (121C) until the desired color is reached – caramelizing the sugars. A wide variety of colors are possible depending on the temperature and time of the kilning and often, they will be indicated by their Lovibond color numbers, such as Carmel 10, or Carmel 120.

Caramel and Crystal malts have no diastatic power, so they are to be used as adjuncts and never as a base malt. Also, many of the sugars in the malt caramelize during roasting and become unfermentable, which is why caramel malt adds sweetness and body to the finished beer. Carmel/Crystal malts also improve the head retention of a finished beer. Those kilned at higher temperatures generally have a stronger caramel flavor. Generally, caramel makes up 2-15% of the grist, but in some cases may be slightly higher.

Flavors associated with crystal/caramel malts in include raisin, honey, plum, prune, toffee, burnt sugar and caramel.

Question 23

What is the final stage of malt preparation?

Answer 23

Storage. The malt must be stored. If used right off the kiln, there will be great problems of wort separation or ‘loitering.’

Freshly kilned malt performs poorly in the brewhouse (most likely because of uneven moisture distribution throughout the batch). Milling and lautering are easier when moisture levels are “equalized.” Jean DeClerck, in A Textbook of Brewing, claims that freshly kilned malt is said to saccharify less and give a turbid wort and may also give rise to poor fermentation and colloidal haze in the beer. He states that there is not much scientific data to back this claim but theorizes that it might have something to do with the slight re-absorption of moisture. He also points out that a rise in diastatic power during the storage period can occur. He suggests that this is due to the liberation of amylase enzymes from “some kind of combination.”

Question 24

What is the Maillard reaction?

Answer 24

This is a reaction between sugars and amino acids, where they meld together with heat. They react together to make small complexes that have different flavors and then as the complexes get bigger, they begin to develop color.

Question 25

(For later in Mashing) What is the gelatinization of starch in barley and other grains?

Answer 25

-Starch, in its native state, is not soluble in cold water and is not easily digestible.
-Native starch becomes digestible through gelatinization and liquefication.
-Starch granules will break down in hot water as they take up water, swell, and burst.
-Gelatinization starts only above 120F, and all grains have different gel profiles that progress over various temperatures.
-The gelatinized state is defined by rapid expansion to 30x the original volume and an increase in viscosity at its peak.
-After peak gelatinization temperature, viscosity decreases rapidly as the starch chains burst and loosen into digestible form

In barley, gel ‘onset’ happens at 136F, a gel-peak viscosity at 144F, and a gel completion and a return to low viscosity at 149F.

The swollen and hydrated starch is only ready to be penetrated by malt enzymes only AFTER it passes gel-peak. Malting enzymes active in mashing cannot penetrate and effectively digest starch that has not been gelatinized.

Liquefication is the simplification of starch chains loosened by gelatinization and can only occur after gelatinization.

In brewing, liquefication occurs later during mashing by the actions of the residual malt enzymes.

Question 26

What do brewers mean by malt extract?

Answer 26

This is the total malt carbohydrates and proteins dissolved in the wort and measured by an ‘original gravity’ reading. The variety of barley, growing conditions, and malting processes all affect malt extract potential. Lager kernels tend to produce more extract.

Question 27

In what ways are barley malt colors measured after drying/kilning?

Answer 27

The course suggests that Lovibond is used to measure malt color, and SRM and EBC measure beer color.

“Degrees Lovibond” or “°L” scale measures the color of a substance, usually beer, whiskey, or sugar solutions. Determining the degrees, Lovibond takes place by comparing the substance’s color to a series of amber to brown glass slides, usually by a colorimeter. The scale was devised by Joseph Williams Lovibond. The Standard Reference Method (SRM) and European Brewery Convention (EBC) methods have largely replaced it, with the SRM giving results approximately equal to the °L.

Question 28

What gives smoked malt its flavor?

Answer 28

Rauchmalt is a malt dried over an open fire made with beechwood logs. It is a specialty of the Bavarian region of Franconia in Germany. Rauchmalt adds the phenols guaiacol and syringol. These give a beer a smoky aroma and taste, sometimes described as “campfire” or “barbecue potato chips.” These phenols are a distinguishing characteristic of rauchbier, a Bamberg specialty with powerfully smoky flavors. Craft brewers in the United States and other countries are experimenting with rauchmalt and creating interesting smoky beers that often pair well with food.