CHAPTER 1
INTRODUCTION

CHAPTER 1 OVERVIEW

The story of beer is the story of the rise of civilization. To the stone‐age brewers, making beer must have seemed like magic. The transformation of grain and water to beer is as impressive now as it was then. Today, we can understand the magic of beer through the science of chemistry. From purifying the water to packaging the beer, every brewing step has a scientific background. Science and technology owe more to beer than beer owes to science. Beer brewing led to many fundamental discoveries from the isolation of the first enzyme to the first explanation of a biochemical pathway. Brewing served as the application that drove inventions like pasteurization and mechanical refrigeration. Understanding the chemistry of beer will lead you toward a greater appreciation of the real magic of beer.

1.1 BRIEF HISTORY

Beer Origins

It is likely that our earliest ancestors were using psychoactive materials from the dawn of the human species. Based on practices of traditional cultures, we can guess that the experience could have connected the user, a shaman, to the spirit world. The shaman could then divine the future, heal diseases and injuries, and issue blessings or curses.

We may never know the full story of the first encounter of humans or their hominid predecessors with ethanol, the alcohol in intoxicating beverages. Perhaps it happened like this. A band of hunter‐gatherers finds a rich field of berries and packs as many as they can into bags or baskets. In some containers, the berries at the bottom get crushed. When the group has eaten its way to the liquid, they find a unique but not unpleasant aroma. A short time later they notice the characteristic effects of ethanol, known in our day as drunkenness. The incident makes a big impression on them. After this, whenever they find sweet fruit, they put it in a container for a few days. Most of the time this process yields a drinkable alcoholic beverage. There are two major factors that made this early wine‐making experiment successful. One factor is that fruit has simple sugars that are fermented by yeast. Simple sugars are scarce in nature; they occur in ripe fruit, honey, tree sap, milk, and a few other natural products. The other factor is that the skins of fruits usually harbor yeast, microorganisms that get energy by converting simple sugars to carbon dioxide and ethanol.

Neither of these factors applies to beer, an alcoholic beverage derived from starch. Starch is a storage carbohydrate consisting of complex chains of hundreds of sugar units; yeast cannot ferment it. The usual source of starch is seeds of grain, which typically have less than 2% sugar. Grain and other low‐sugar plants do not harbor yeast. Before fermentation, the starch chains must be broken down to sugar by reaction with water. Enzymes (or extreme chemical treatment) are needed to bring about the reaction. The necessary enzymes are available in human saliva or in sprouted grain, called malt. The saliva process is difficult to run on a large scale, so beer‐making of moderate to large scale depends on the malt process (or an alternative mold‐based process used for rice beer, e.g. sake). To make beer by the malt process, the live seeds are soaked in water and allowed to sprout. This brings the sugar content to nearly 20% based on dry weight. The sprouted seeds are crushed and treated with warm (not boiling) water. The liquid product has a sugar content equivalent to 60‐70% of the weight of the original grain. The sugary liquid is added to a container with yeast, which comes from a previous batch or from added fruit. After a few days of fermentation, the beer is ready to drink.

We can devise a scenario that plausibly accounts for how this process could have been discovered. The cook goes to get grain from the storage pit for the family's meal, but finds that someone allowed the seeds to get wet and they had sprouted. After uttering some sharply worded commentary, the cook grinds the seeds anyway and adds hot water to make porridge. Surprisingly, the mixture is sweet! It was known from experience that a sweet substance can often be fermented to produce an alcoholic beverage. The cook puts some of the porridge into the fermentation calabash. Four days later a not‐very‐tasty, but moderately intoxicating beverage emerges. After a few batches, the technique is refined, the flavor is improved, and the whole village has beer as a reliable intoxicant.

Now we leave aside speculation and consider actual archaeological findings. Evidence was discovered in Raqefet cave in Mount Carmel in present‐day Israel that beer was being made from malted cereal grain (seeds of grassy plants) as early as the Upper Paleolithic period, 13,000 years ago. This is long before agriculture was practiced, so it must have been difficult to gather enough grain for a batch of beer. Agriculture, which is the intentional cultivation of a desired species, in this case cereal grain, is needed to provide a consistent supply of beer. Because grain does not harbor the yeast needed for alcoholic fermentation, many grain‐based prehistoric fermented beverages were supplemented with fruit or honey. The earliest chemical evidence of such a mixed beverage comes from eight or nine thousand years ago in Jiahu, Henan province, a Neolithic site in the Yellow River Valley. Analysis of the contents of some of the earliest pottery ever found revealed a beverage formulated from rice, fruit (grapes or berries), and honey. The earliest chemical evidence of barley beer comes from excavations at a prehistoric town, called Godin Tepe, located on what eventually became the Silk Road in the Zagros Mountains in western Iran (Fig. 1.1 site 5). Pottery jars from 5500 years ago contained calcium oxalate (CaC2O4), a signature of barley beer production.

Figure 1.1 Locations of sites.

Source: Modified from The World Factbook. CIA. https://www.cia.gov/library/publications/the-world-factbook/docs/refmaps.html

The first known written language (although not necessarily the first use of written symbols) came from Sumer [SOO mer], a civilization of city states in southeastern Mesopotamia (now Iraq) at the downstream end of the Tigris and Euphrates Rivers (Fig. 1.1 site 7). The earliest writing, from about 5400 years ago, was utilitarian, mostly recording transfers of goods. Sumerian and other Mesopotamian languages were written with symbols, called cuneiform, that were made with a wedge‐shaped stylus pressed into moist clay tablets (Fig. 1.2). Dried clay is durable; many ancient cuneiform documents survive and have been translated. Some of the earliest of these record the production, consumption, and transportation of beer. These tablets document a fully mature brewing culture, showing that beer was old when writing was new. One famous cuneiform tablet from 3800 years ago has a poem called Hymn to Ninkasi, a poem of praise to the Sumerian goddess of beer. The Hymn has a poetic, but not completely comprehensible account of how beer was made. The Sumerians made beer from bappir, and malted emmer wheat and barley, and flavored it, perhaps with honey. Most sources hold that bappir was a type of bread, but evidence for this is scant and some scholars are not convinced. Residues from food‐making processes in ancient Sumer seldom survive in the humid climate. Sumerian documents mention beer frequently, especially in the context of temple supplies. Beer was also considered a suitable vehicle for administering medicinal herbs.

Figure 1.2 Cuneiform Sumerian‐Akkadian dictionary of brewing terms. Metropolitan Museum of Art, New York.

Babylon and Egypt

Dominance over the Mesopotamian region passed back and forth among the Sumerian cities until they were conquered by Sargon of Akkad about 4300 years ago. Akkad was somewhat up‐river from Sumer, sharing the same culture, but speaking a different language F(Fig. 1.1 site 9). Akkadian dominance lasted about 250 years, after which was a period of smaller‐scale kingdoms that seldom lasted much more than 100 years. Around 3800 years ago, the Amorites under Hammurabi of Babylon briefly unified much of Mesopotamia. Babylon was a city on the Euphrates, up‐river from Sumer (Fig. 1.1 site 4). Beer made from barley or emmer (Triticum turgidum, an ancient form of wheat) was a staple of the Babylonian diet. After Babylon, Assyria (Fig 1.1 site 7) ruled the Middle East from its two capitals, Assur and Nineva. The Assyrians were displaced by a second wave of Babylonians, among whom was Nebuchadnezzar, the conqueror of Jerusalem. Throughout all this warfare, these cultures continued the brewing tradition of Sumer.

It is believed that brewing may have spread from the Mesopotamian region to Egypt, about 800 miles (1300 kilometers) away in Africa, but it is also possible that Egypt was first and Sumer later. Evidence of large‐scale beer brewing 5500 years ago has been discovered in Nekhen (Hierkonpolis) in the Nile River plain...