Yay, more beer-related science!
This time, it’s around the chemistry involved in that lovely bitterness in beer. As it turns out, this bitterness is provided by a class of chemicals* called alpha acids, which are to be found in the resin of mature hops.
For those living in New Zealand and enjoying the local craft beer industry’s obsession with hoppy beers – you know what I’m talkin’ about, bitterness-wise :)
Anyhoo, one of the major such acids is called humulone, and it’s about this that we’ll be talking. During the brewing process, humulone degrades into two isomers**, which are both far more soluble than humulone itself. Up until now, there’s been a great deal of confusion about these isomers and their formation.
And so in have stepped the scientists and, in this case, their ability to perform x-ray crystallography. The technique takes the crystals of a compound, and then bounces x-rays off of them – how the x-rays diffract gives valuable information on the compound’s physical structure.
And what this group found was that the common notions around humulone (and its derivatives’ structure) have been…incorrect.
Why is this important? Well, it’s simple. There have, increasingly, been claims that beer (and what makes it bitter), in moderate amounts, can be beneficial for a number of illnesses and complaints***. Some of the claims have linked specific alpha acid isomers (i.e. specific bitternesses) with specific benefits.
The problem is, though, that the configuration of these isomers, and how they’re formed, has been a source of confusion for decades. In turn, this prevents the development of any good structure-function relationships for these compounds. If we knew exactly what does what, we can get better at getting the most goodness out of our beer habits. Hell, we may even be able to give people supplements, say, containing only the beneficial compounds. Why anyone would want to lose out on drinking lovely, lovely pints in the process is beyond me, but that probably says more about me than anyone else :P
Or, as the authors put it:
Excessive beer consumption cannot be recommended to propagate good health, but it has been demonstrated that isolated humulones and their derivatives can be prescribed with documented health benefits.21 The absence of correct stereochemical assignment for these compounds has prevented verification of the actual species responsible for biological activity.
So there you have it. With a bit of luck, one day we’re going to know exactly which alpha acid isomers are good for what. Can you imagine being prescribed certain types of beer? It’s certainly a less bitter pill to swallow for many, as it were :P
And yes, I did indeed toy with doing an ‘up-goer fiver’ on this :P
Also, amuse that this was published in a German journal…
Urban, J., Dahlberg, C., Carroll, B., & Kaminsky, W. (2013). Absolute Configuration of Beer′s Bitter Compounds Angewandte Chemie, 125 (5), 1593-1595 DOI: 10.1002/ange.201208450
* Yep. CHEMICALS. You know, the stuff everything’s made from. Not ‘chemicals’ in the sense of ‘ew, chemicals, they’re bad for you’.
** Isomers are, basically, different forms of the same thing – to be more precise, they’re compounds ‘ isomers are compounds with the same molecular formula but different structural formulas’ (thanks, Wikipedia). Sometimes they’re mirror images of each other, and sometimes it gets quite a bit more complicated than that.
*** See Beer: Can it help fight off the common cold?, for example. Also, read the paper this post talks about for more examples of other complaints beer has been linked to helping fight.