With Fathers’ Day just a couple of days away, I thought I’d do my inaugural cooking science post on something near and dear to many fathers’ hearts: beer.
Beer – it does a body good. No, wrong liquid.
Beer – it’s what’s for dinner. Well, maybe for some.
Beer – the other white meat. See above.
Ok, enough goofing around – this is serious science here.
So what is beer? We’ve all seen the commercials: pure mountain spring water, malted barley, American-grown Cascade hops… but what are those things, what do they contribute to the final product, and why does it make you feel the way it does?
Let’s start with yeast. Yeast is the one thing they don’t mention in the commercials, but it’s what gives beer its intoxicating properties. Yeast is a microorganism (a fungus, actually, but I don’t want to gross you out) that can thrive in environments with very little oxygen. Most energy-producing metabolic processes (converting glucose into energy) in oxygen-rich surroundings produce only energy and two end products: carbon dioxide (CO2) and water (H2O).
Without the oxygen, though, the glucose is broken down into: energy + CO2 + alcohol (2CH3CH2OH). This process of energy production in a cell in anaerobic conditions (w/o oxygen) is the very definition of fermentation.
We all know it’s the alcohol from the fermentation process that produces the physical/mental effects of beer, but why and how does it do that?
Essentially, alcohol molecules have a chemical nature that allows them to easily penetrate cell membranes. The alcohol molecules have hydrocarbon groups similar to fats, and a very water-like -OH group on one end. This makes it possible for alcohols to mix easily with both water (like the contents of your cells) and fats (like a cell membrane).
When alcohol enters your cells, it causes disruptions to the normal functioning of those cells. Disruptions to the cells of our central nervous system bring on our feelings of intoxication.
Up there, I said that fermentation requires a source of glucose (a monosaccharide, or simple sugar). In winemaking, that’s easy* – grapes are naturally full of glucose.
Beer, though, is brewed from grains that contain starches instead of glucose. The good news (in this case) is that starches can be broken down into simple sugars through a process called malting. In this two-step process, the grains (usually barley, but sometimes wheat, rice, millet, etc) are soaked in water until they sprout (usually a few days), and then heated and dried.
The sprouting grains produce enzymes (molecules that speed up reactions) that will break the starches down into their component sugars. The heating stops the growth process so that you’re left with lots of simple sugars to feed the yeast. The dried end product (barley malt) is often ground and can be stored for long periods of time.
Flavoring & Preservation
The beers of 1000+ years ago were basically just water, malted grain, and yeast, and they were consumed soon after brewing because they would spoil. Flavoring agents that doubled as preservatives were first added to beers about that time. Some of the first were rosemary & coriander, followed not too long afterwards by hops.
Hops are little cone-shaped flowers of the vine Humulus lupulus that have aromatic compounds in their sap and in little oil glands at the bases of their leaves. The sap compounds (humulone & lupulone) provide a bitterness to the brew, and those from the glands (mostly terpene myrcene) provide aroma. These same compounds also delay spoilage.
Now that we’ve run through some of the theory, we’ll take a quick look at how that all comes together in the process of making beer:
Mashing: the dried barley malt is soaked in water, getting the starch-breaking enzymes fired up and doing their job. The end result of the mashing process is a sweet brown syrup called wort.
Boiling: hops are added to the wort and they’re boiled. This pulls the flavoring compounds out of the hops, stops the enzymatic activity of the mashing, kills any bacteria, and concentrates the wort.
Fermentation: yeast goes into the cooled wort and fermentation begins.
Conditioning: getting rid of the spent yeast and other impurities.
Time for a cold one
Obviously, this is a very complicated subject that I’ve given only the most cursory overview of (and even that ended up being twice as long as I expected). There are lots of other things we could have gone into, but I’m hopeful that this is enough background for now.
So the next time you pop open a can of Pabst Blue Ribbon, or a bottle of Racer 5 (my own fave at the moment), you can think about all of the history and chemistry and microbiology that went into that brew. And don’t forget to regale your husband or dad (or wife or mom, for that matter) with the story of their favorite beer – I’m sure they’ll be highly impressed!
*I realize that there’s really nothing ‘easy’ about winemaking and it takes a huge degree of skill and artistry. It’s just that the fermentation step is easier to get going.