Before fermentation can take place, yeast, a single-cell fungus occurring naturally in several varieties, must be allowed to act on the sugar present in grain. This releases two crucial by-products, alcohol and carbon dioxide. A grain often used for this purpose is barley - even though, in its natural state, it contains only a trace amount of free sugar - because of its high content of starch, a complex polymer of sugar. Barley also contains substances known collectively as diastases, which convert the barley starches into sugar to be used as food for the growing plant. When barley is crushed and dried carefully, the essential starches and diastases are released and preserved, rendering a substance called “malt. ”
Until sometime around the ninth century, “beer” was actually “ale,” made by a process known as mashing, whereby the barley malt was mixed with hot - but not boiling - water. The effect of the hot water was to induce the diastases to act immediately in breaking down the complex starches into sugar. This process is referred to as conversion and results in “wort,” one of its most essential products. The mashing procedure not only produced the brown, sugary wort but also permitted inert elements of the barley, such as the husks, to be drawn off. In the production of pure ale (such as the first human brewers would have made), all that remained was for yeast to act upon the wort so that the sugars could be converted into alcohol and carbon dioxide.
Beginning in approximately the ninth century in central Europe (authorities vary widely and wildly regarding the date but not the place), the procedure began to be modified, and beer came into being with the addition of blossoms from the hop plant. Numerous modern beers are labeled as ale, but as mentioned, technically “ale” means unhopped beer. In order to convert ale into beer, dried hop blossoms are added to the boiling wort mix after the mashing but before the yeast is allowed to act. This releases two resins, lupulon and humulon, that act as excellent natural preservatives, preventing the growth of certain types of bacteria which, although harmless to humans, are detrimental to beer. Before the use of hops, pure ale had a very limited “shelf life” and often spoiled, much as milk does. The diastases in barley also acted against the bacteria in question, but not nearly so effectively as hops. In fact, it can be argued that it was the harnessing of the preservative power of hops that permitted the production, storage, and distribution of beer in large quantities. Moreover, in addition to its antibacterial properties, the hop plant adds flavorful oils that mask the otherwise sweet taste of pure ale (Kloss 1959: 31-2).
World History
