Lagers are boring. When you pop a can of lager beer, you taste the product of closely related strains of Saccharomyces pastorianus. Their genetic variety pales in comparison to the small but diverse group of yeasts used for making ale and wine, which pump out vastly different metabolic by-products and a wide range of flavors. In fact, lagers have looked and tasted much the same for hundreds of years because breeding strains with new brewing characteristics and flavors has proved difficult; the hybrids were effectively sterile. But that is about to change.
This good news harks back to the 15th-century origins of lagers. S. pastorianusappears to have been bred after an accidental cross of two other yeasts in a cool, dark cave in Bavaria when monks began “lagering,” or storing beer. In the 1980s scientists determined the identity of one original parent: Saccharomyces cerevisiae, which is the mother of all yeasts used in baking and brewing. The other remained unknown until 2011, when Diego Libkind, an Argentine microbiologist, identified Saccharomyces eubayanus in the forests of Patagonia as the missing link. Wild S. eubayanus was not well adapted for industrial brewing, but its discovery opened up the possibility of developing new yeast crosses. “Once eubayanus was discovered, things suddenly became very interesting,” says Brian Gibson, who studies brewing yeasts at the VTT Technical Research Center of Finland in Espoo.
Barley beer is a form of alcoholic beverage, made in central Europe at least as long ago as the Early Iron Age, about 600 BC. The earliest fermented drinks have been found in China at the Neolithic Jiahu site, ca. 7000-5800 BC. The earliest evidence of brewing beer from fermented barley and wheat is known from the Mediterranean Bronze Age of Mesopotamia (ca. 4000 BC); although Peter Damerow
has recently suggested this brew might not have been terribly alcoholic.
The crucial beer-making step of sprouting the grain (called malting) was reported in the 4th century BC by Zosimus of Panopolis. The Greeks and Romans were snobs when it came to drinking: wine was a drink for men, they said, and fermentation to make beer an unnatural and impure process suitable only for women and effeminate men. It is quite possible that the modern manly Western love for beer comes to us direct from the Iron Age "barbarians" of central Europe.
Barley beer recipes were reported in the writings of Romans in the first centuries BC and AD, such as Diodorus and Posidonius of Apameia. These writings describe the Roman social status related to alcohol consumption: at least on some level, wine was for rich people; middle class people drank beer made from wheat and mixed with honey. Barley beer (or corma) was the home brew of the lower classes, made from sprouting six-rowed barley (Hordeum vulgare) grains and toasting them in the oven.
Production of barley beer, the way it was practiced in Iron Age Europe, involves harvesting barley and soaking the grains for a period of time. The wet grains are spread out on a flat surface and turned until the grains sprout: that's the malting process. After the grain has sprouted, the malted grains are dried in a kiln at a fairly low temperature (ca. 80 degrees C). After the grain is cooled, the malted and dried grains may be stored for later use.
Next, the grains are coarsely ground and water is added. The dissolved malt is mashed into a pulp, and the pulp is heated at low temperatures, perhaps using a stone boilingtechnique of adding heated rocks to the liquid. The low temperature causes the malt sugars to caramelize, and the fermentation process begins. After that, the mash is purified by filtering, and flavored. Hops were not used in beer until the Middle Ages, but archaeological analysis of the Iron Age sites suggests that barley beer might have been flavored by mugwort and carrot, among other things.
Evidence of Iron Age barley beer production comes from sites such as Roquepertuse in the Etang de Berre region of Mediterranean France (best known for its later Celtic cult shrine), and the Hallstatt culture site of Hochdorf in central Germany (best known for a rich princely grave).
The beer-making equipment found at the early Iron Age occupation (ca 450 BC) at Roquepertuse in Provence, France, is simple, and likely reflects production only for use by the household. The process took place indoors, in a room with both a hearth and an oven or kiln. The kiln at Roquepertuse was small but elaborate, with two chambers separated by a narrow opening. The embers were contained in the lower chamber, and the heated air rose through the opening into the the upper chamber, where the food was placed for cooking. Such an oven could well have been used for drying barley grains. Storage jars were found at Roquepertuse, including a few sherds of wine amphorae from nearby Marseille, which shows that the Roquepertuse occupants did enjoy a bit of wine when they could get it.
By contrast, the site of Hochdorf, a La Tene and Hallstatt period site (ca 550 BC) in Baden-Württemberg Germany, contains evidence of what is clearly mass production of barley beer. Features at Hochdorf associated with beer-making include six carefully constructed ditches, each 5-6 meters long, 60 centimeters wide and up to 1.1 meters deep. The ditches were straight with a U-shaped profile, straight walls and floors; they were probably lined with boards. Botanical remains found within these ditches included almost only grains of some kind; two of the ditches included thousands of sprouted multi-row barley grains. These ditches are believed to have been used for drying the green malt and/or germinating the grains, and possibly as a kiln although a furnace has not been identified associated with the ditches.
Whether made in small quantities or large, barley beer must be consumed within a couple of days before it goes bad. A large party is documented at Hochdorf, in association with the burial of their chieftain, and it is tempting to connect the beer-making equipment at the rural residence with the large feasting ritual in evidence at the grave site.