A quick note about Gravity & IBUs

So, while at a BBQ this past weekend I was chatting with someone (thank you Shawn) about beer and they were asking what the hell the stats are that I put for each of my reviews alongside alcohol by volume (ABV). I realized it might be worth spending some time going over what these measures (IBU and Gravity) are in a bit more detail. I gave a somewhat brief overview on one of my earlier posts, but this should give a more in-depth explanation of some of these figures for anyone who cares to read this blog! I will consider that ABV is self-explanatory and will not go into any further detail, since it's just the overall alcohol content of the beer.

IBU: this abbreviation stands for International Bittering Units. This measure is essentially the measure of alpha acids (provided by hop cones - see picture above for what hops look like) and is measured in parts per million (ppm or mg/L) in the finished brew. A quick interpretation is that as your IBUs rise, so do the bitter flavors that the beer presents to your palate. However, it is generally accepted that human detection of differences in IBUs is a somewhat weak ability; what this means for you is that any difference in IBUs between beers that is approximately 6 IBUs or less will not strike you as being any different.


Most beers I have seen typically range from 5-10 IBUs to maybe 100 IBUs. The 100 IBU beers are going to be your ridiculously strong and hoppy IIPAs (Imperial India Pale Ale) and the like. Bud/Coors/Miller Light are all going to be in the range of probably 8-12 IBUs. Ambers will probably be in the 20-40 range; American Pale Ales in the 30-50 range, etc.


Most people think of hops and think of pure biting bitterness, but in reality hops do a lot of different things for beer. Without going into too much detail, hops are added while you are boiling the wort (essentially the sugars resulted from mashing and boiling grains...these sugars are necessary for consumption by the yeast that you add after the boil and cooling so that the beer can ferment and create alcohol). Most recommend boiling the wort with hops for an hour, which is chopped up into a few different types of additions (I am not going to get into different types of hops, their alpha acids and whatnot): bittering hops and finishing hops. Bittering hops are (typically) added for the entire duration of the boil and that's where the bitterness in your beer comes from. Finishing hops are added at various parts of the boil (usually 15 to 20 minutes left in the boil as a general standard). The purpose of the finishing hops are not to add tons of bitterness, but rather to give much of the hop flavor (yes, hops have different flavors, not just bitterness) such as floral, herb, leafy, spicy, grassy, citrus-y, piney, etc. etc. the list goes on. There are a lot of different ways to hop a beer but I'm not going to get into all of that here.

Gravity: So, the gravity of a beer is essentially how dense the beer is, and can be generally measured using two systems: Degrees Plato or Original Gravity (OG). Don't be overwhelmed by this, as a simple conversion can be calculated to get to one or the other. So, let's say that a beer is 20 degrees plato. Each degree Plato can be perceived as .004 OG units; as such, a 20 degree Plato beer would translate to 1+(20*.004) or 1.08. This 1.08 OG can be interpreted as the beer being 1.08 times as heavy as pure water. Again, for a comparison: Bud/Coors/Miller Light would be somewhere in the neighborhood of 1.025 - 1.04 most likely. American Pale Ales would probably be 1.045 - 1.06, whereas something like a Russian Imperial Stout would be in the neighborhood of 1.075 - 1.115 (at this point your beer is going to be somewhat "chewy"). Not quite my thing - I tend to like lighter bodied brews, but there are others who most certainly disagree. IIPAs will most likely be like 1.075 - 1.090, so quite heavy, but I am fine with it as long as it's HOPPY :-)


At any rate, hopefully this is (at least somewhat) helpful to anyone out there who wants to learn more about beer, or who is reading this blog and wondering what the hell kind of foreign language I'm speaking with all of these abbreviations. Next time you drink a beer see if you can pull up some info on it online. The ABV is often on the bottle/can, but IBU and Gravity are typically harder to find. As an aside, many brewers will not disclose their IBUs or Gravity for fear of someone "reverse engineering" their beers. It may sound crazy, but there are a lot of avid home brewers out there who can identify certain tastes and who try to make spot-on clones of beers they have tasted previously. While I can understand the paranoia, it does suck for someone who is interested in it for purely evaluative purposes.


I hope that, if you're reading this, you're leaving more educated about your beer drinking than when you started reading this post!


Cheers,
Hurls