BEER INGREDIENTS - WHAT ARE THE INGREDIENTS OF BEER?

Beer is a fermented beverage made from a source of starch without concentrating the alcohol. The composition of finished beer varies, but the approximate averages for the major components of American commercial beers are about as follows: beer composition

Water 92.9%
Ethanol 3.9%
Carbohydrates 2.5%
Carbon dioxide 0.5%
Protein 0.2%

This simple analytical result masks a complex reality. Hundreds of minor components not listed above are big players in the flavor and character of the beer. Instead of taking on the issue of what is in finished beer, we will look at how beer becomes beer.

The usual ingredients for beer are water, malt, hops, yeast, and adjuncts. Adjuncts are materials that supplement the malt by providing additional starch or sugar.

Malt
Malt is seeds of grain that are allowed to sprout and are then killed by heating. Most beer malt is made from barley (Hordeum vulgare) seeds. Wheat is used for certain styles; oats, rye, sorghum, millet, and others are occasionally used for specialty or regional styles. Malt serves as a source of starch and also provides enzymes to break down the starch into sugars that can be fermented.

Barley, among the first plants domesticated as a crop, seems to have originated in what is now the Israel–Jordan area. As a consequence of its importance to civilization, some ancient religions used barley in their rituals.

Barley is mentioned many times in religious texts including the Bible. Each barley plant has one or more stems that, for modern varieties, extend 2 to 3 feet (60 to 90 centimeters). The stem is divided by joints called nodes, each of which has a leaf. The flowering head grows from the top node.

There are groups of three closely spaced flowers at points along one side of the stem of the flowering head. The next group of three flowers is on the other side of the stem. This gives six rows of flowers.

In some varieties of barley, all the flowers are fertile, so after fertilization there are six rows of seeds, called corn. These varieties are called six-row barley. In other varieties of barley, only the central flower of each group of three is fertile, so there are two rows of corn.

These varieties are called two-row barley. The barley corn has a groove in the front (ventral) side where it grew against the stem. The corn is covered with interlocking woody shells called hulls, one in front and one in the back; the back hull extends to form a characteristic awn, also called a beard.

Beneath the hulls is a waxy seed coat. Beneath the seed coat is a layer of living cells called the aleurone layer. There is a hole in the seed coat, called the micropyle, where the hulls meet at the end of the corn away from the awn. The micropyle can admit water. The baby plant, called the embryo, is at this end of the corn.

The compartment containing the embryo is separated from a compartment containing starch, called the endosperm, by a divider called the scutellum. The endosperm contains granules of starch, each surrounded by a protein coat.

Whether the beer is to be made from barley or some other grain, the seeds are first converted to malt, a process called modification. The live seeds are soaked in water (“steeped”) on and off for about two days. They are then put into a box or spread on a floor, provided with moist air, and turned regularly.

During this period the embryo wakes up and releases chemical messengers called hormones. The hormones direct the cells in the aleurone layer to produce enzymes. The enzymes break down the proteins and starch in the endosperm so that the embryo can use them for nourishment until it is able to produce its own food from sunlight.

Before this process goes too far, the maltster puts an end to it by heating the germinating seeds in a huge oven called a kiln. The temperature is held at 175 to 212 °F (80 to 100 °C). Longer kilning at higher temperatures gives darker, more flavorful grades of malt, but these treatments also destroy a larger fraction of the enzymes.

Hops
The hop is a climbing plant, Humulus lupulus. Hop flowers, which look like little pine cones, are used to flavor beer. There are many varieties of hops with names like “Cascade” and “Spalt.” All give bitterness, but the different varieties of hops give different flavors.

Hops are like wine grapes in the sense that the details of the growing temperature, soil, moisture, and other climate issues affect their flavor. Wine makers deal with variations in grapes by marketing wine as “vintages.”

Consistency in wine is not expected from one year to the next. Brewers do not have this luxury. Some use mixtures of hop varieties so that the proportions can be modified to adjust for local and seasonal variations.

Small craft brewers cannot usually keep a big hop inventory on hand, so their product is not as consistent. In the Northern Hemisphere hops are harvested in the late fall and must be dried and cold-stored until used to make beer.

Yeast
Yeast is a single-cell fungus that reproduces by budding. Hundreds of species of yeast have been characterized. Of these, two are usually used for beer making. Saccharomyces cerevisiae, known as top fermenting yeast, is used in ale, and Saccharomyces pastorianus, a bottom fermenting variety, is used in lager. There are some other species of the genus Brettanomyces that are used in a Belgian ale style called lambic.

Water
You know about water. It turns out that traces of various minerals naturally present in water affect beer in important ways. The chemistry of water is the chemistry of life.

THE CHEMISTRY AND BEER HISTORY

Beer has played an important role in chemistry and biology both from a historical and from a technical point of view. Although many mistakenly attribute the discovery that beer yeast is a living organism to Louis Pasteur (1822–1895), it was reported nearly simultaneously by Charles Cagniard-Latour and Friedrich Traugott Kützing in 1837, and Theodor Schwann in 1839.

This observation was strongly attacked by the leading chemists of the time, including Justus von Liebig (1803–1873). The mocking, dismissive tone of their attack seems more characteristic of political talk radio of our own time than scientific discourse.

Liebig was eventually driven back from the position that yeast are not living, but to his death he opposed the idea that they are responsible and necessary for alcoholic fermentation. This bitter and fruitful scientific controversy over the nature of fermentation continued between Liebig and Pasteur, ushering in the modern age of biology.

Liebig held that fermentation was a nonliving process in which the decaying matter contributed its energy to the breakdown of sugar. Pasteur held that fermentation was a part of the life processes of the microorganisms that were involved with it. The results and arguments of both men were hijacked by followers of the doctrines of vitalism and mechanism.

The vitalists believed that the processes of life could never be explained by the laws that govern ordinary matter. The mechanists believed that living systems follow the same laws as nonliving systems.

Now, 150 years later, we can say that Pasteur was right that all the fermentations that he, Liebig, and anyone else observed were caused by microorganisms. Liebig was right that fermentation is an ordinary chemical process that could, under the right conditions, occur without the participation of living cells.

Eduard Buchner (1860–1917) proved this in 1897. Buchner ground up yeast in the presence of abrasives and squeezed out fluid through a cloth. When sugar was added to this fluid, carbon dioxide and alcohol were produced, exactly the same reaction as occurs in live yeast cells.

Buchner won the Nobel Prize in chemistry in 1907, the first awarded for a biochemical discovery. In retrospect it is clear that Liebig and Pasteur did not allow themselves to be governed by doctrines like vitalism and mechanism. Pasteur was the first person to apply the principles of microbiology, a field he helped found, to the brewing of beer.

Many advances in chemistry were driven by the needs of the beer industry. These include measurement of temperature and of specific gravity. The Carlsberg Laboratory, set up in Copenhagen in 1875 (one year before Thomas Edison’s laboratory in Menlo Park) as an arm of the Carlsberg brewery, was the site of several important discoveries.

Emil Christian Hansen (1842–1908) was the first to raise up pure cultures of yeast (or any microorganism) on an industrial scale. The first reliable method of protein analysis was put forward by Johan Kjeldahl (1849–1900). The concept of pH, which is central to water chemistry, was introduced by S. P. L. Sorensen  (1868–1939). The Guinness brewery in Dublin gave us the statistical method called Student’s t-test, invented by William Sealy Gossett (1876–1937).