Monday, January 6, 2014

Auto-Brewery Syndrome

The yeast Saccharomyces cerevisiae
As 2014 gets into full gear, I am thinking about one of the most intriguing science/medicine news stories that we saw in 2013: auto-brewery syndrome.  This is one of the weirdest diseases I've heard of in quite a long time.  In auto-brewery syndrome, yeast that live inside your gastrointestinal tract ferment carbohydrates like sugar and starches into alcohol that can actually make you drunk.  

This sounds like a made-up disease, but a few cases of this happening have really been reported in medical literature.

It seems like, while very rare and still controversial, it might be possible for yeast inside your body to make enough alcohol to actually intoxicate you.

Thursday, January 2, 2014

Chemistry of Beer, Part II: Freezing Point Depression and Fractional Freezing

I'm sitting here in Pittsburgh, watching the snow fall and thinking about how cold it is outside.  Often when traveling to visit friends or having friends visit during the winter months, someone will ask a question like, "I have a bottle of wine in the trunk of my car.  Can I leave it in there overnight or will it freeze?"  The answer depends on both the outside temperature as well as on the nature of the wine itself.

Throwing a bottle of white wine or a couple of beers into the freezer to cool them down quickly is a common practice.  Because of this, many people probably already recognize that alcoholic beverages like beer or wine take longer to freeze than water.  However, as anyone who has left beer in the freezer for too long will also already know, beer will freeze.   So will wine.  Perhaps confusingly, other alcoholic beverages like vodka can be kept in the freezer permanently, because they just don't freeze at normal freezer temperatures.

Why does alcohol lower the freezing point of liquids and why do different types of alcoholic beverages have different freezing points?  This is a question that I wanted to explore in this blog post.  The answer has important implications for everyday life that reach far beyond the realm of beer.  Like the previous post on beer, this topic gives us a vehicle to explore some very general scientific principles.