I am going to deviate from my normal focus on the 18th Century to discuss some brewing terminology that seems to be confusing people in craft brew pubs. The other day, my wife and I visited a brewery and her questions about the beer menu prompted me to clarify some jargon that are too often showing up on the menu and to the non-brewer can be confusing. Today, I just want to share the definitions. In future blogs I will discuss how brewers (both Colonial and modern) determine these factors and use them to craft better beers.
|ABV||Alcohol by Volume (%). This is the percentage of ethyl alcohol in your beer. Machismo aside, more is not necessarily better. Alcohol is created by the fermentation of sugars (generally maltose) and to get high ABV, you must start with lots of sugars. Generally speaking, high ABV beers are sweet as there must be excess sugar to drive up the alcohol content. I find the ideal range for ABV to be 4 – 7%.|
|Plato||One way to determine ABV is to measure the specific gravity of the wort before and after fermentation using a Plato hydrometer (named for Fredrick Plato). Solutions of sugar have higher density than solution of alcohol so as the wort ferments, the specific gravity falls. The difference in gravity is correlated to the ABV.|
|BRIX||Another way to determine ABV is to measure the concentration of optically active sugars. Biological molecules like sugars are specific enantiomers which are “mirror image” isomers. The maltose in wort is levorotary meaning it causes polarized light passing through the solution to rotate to the left. Alcohol has no enantiomers so by measuring the decrease in this rotation using a BRIX refractometer, we can determine the amount of sugar converted to alcohol.|
|Lovibond||Joseph Lovibond a London brewer developed a color scale based on panes of stained glass to measure the beer. The higher the Lovibond number the darker the beer. Color in beer does not correlate to strength but it does impact flavor since the majority of beer color is due to caramelization of the sugars (Maillard reaction) when malt is roasted.|
|EBC||The Lovibond scale is a simple tool but it is not easy to use and is subjective. The European Brewing Convention (EBC) scale uses modern analytical equipment, a spectrophotometer, to measure how much light is absorbed at a specific wavelength (430 nm).|
|IBU||Hops imbue bitterness in beer and International Bitterness Units (IBU) is a measure of how much bitterness from hops has been added to the wort. Technically, IBU can only be determined with advanced analytic equipment (Gas Chromatograph) but most brewers are able to estimate IBU by computing how much humulones or alpha acids from the hops extracted into the wort by considering the amount present in the hops and the time those hops are exposed to the wort. The higher the IBU, the more bitter the beer but this is not a direct relationship. Bitterness is perceived differently in malty dark beers than in pale light beers. In my opinion, however, the ideal range for IBU is 40-70.|
|Duple, Triple, and Quad||Technically, these are measures but rather beer styles but a note here is to help you with the beer menu. Triples and quads are typically Belgian and Dutch strong ales where excessive amounts of malt are added to the wort in order to drive up the alcohol content and sweetness in the beer. Duples have twice the malt (4 lbs/gallon). Triples have three times the malt and quads have four times the malt. These beers are able to achieve excessive ABV but require skill to make sure they are not cloyingly sweet.|
We will discuss these more in the context of the Colonial Brewer in future blog posts but I hope this brief explanation of some of the jargon that is beginning to appear on the menus of many craft breweries helps you to make better decisions. Like any human endeavor, brewing has its own language. Knowing the language makes it easier to engage in the conversation.