Yesterday I sampled Ballast Point’s Pale Ale, followed by its creamy Calico Amber Ale — made especially milky by a nitrogen tap — then tried the Black Marlin Porter, wrinkled my face into a lemon-sucking grimace after a few sips of the Tongue Buckler Imperial Red and finished the evening off with the Habanero Sculpin IPA.

All in the name of science, of course.

Anyone who’s been on a brewery tour or has seen someone attempt home brewing knows the boiling, fermenting and filtering that goes into making beer, and so probably wouldn’t be blown away by the fact that science is involved in the process.

But when Ballast Point’s head brewer, Yuseff Cherney, gave a tour of his operation as part of the week-long San Diego Science Festival, he managed to work in words like flocculation (the clumping together of beer yeast, which allows it to be filtered out), centrifuge (a piece of equipment that spins really fast to suck the solid out of a liquid) and aerobic and anaerobic activity (respiration in the presence and absence of oxygen, respectively).

The festival is put on by the University of California, San Diego to show off all the science and engineering that goes on in San Diego. Mostly that involves work done at our city’s research institutes and tech companies, but when you think about it, it also includes our famed microbreweries. There are at least 10 breweries in San Diego that make specialty beer, and as Cherney demonstrated, there is a lot of science and technology involved in the process.

While Cherney said he usually gives 15 minute tours of Ballast Point, our tour spanned more than an hour and took us through the scientific explanation of every step in the beer-making process. (This might be in part due to the fact that Cherney is a UCSD grad who spent late nights in college making brewer’s yeast in a school lab with a friend.)

Let me say right now that I’m no way near anything resembling a beer expert, and really only learned to enjoy a few local brewery creations last month. But Cherney’s tour definitely upped my appreciation for the craft involved in making, well, craft beer, and I think I was able to better enjoy the (many) beers I sampled at the end of the tour because of it.

OK, enjoy might be too strong a term for some of those beers I tried. I’m talking about you, Tongue Buckler. Anyway, here are a few of the things I learned:

Mud vs. Stone: Most beer is made from fermented barley, but large beer manufacturers (which Cherney accidentally called “Mud” instead of Miller and Bud — Freudian slip, he said) add in corn and rice to their mixtures because they’re cheaper. These lighter grains give your King of Beers and High Life — not to mention The Beast or Natty Light — their lighter taste.

“That’s what you guys love to drink because you’re Americans, right?” Cherney asked the tour group. He was greeted with the groans you’d expect.

Tongue Buckling Indeed: Beer is boiled to encourage the breakdown of its malts into simple sugars. Hops are added while the beer is boiling, but adding them at different parts of the boiling process produces different effects. Pouring some hops in during the boil gives the beer its bitterness, adding them at the end of the boil creates the hoppy flavor and dumping in extra hops at the end (called “dry hopping”) makes for that special hop-filled aroma.

The amount of hops and when they’re added give beers differing amounts of bitterness, which is marked on a sliding scale of International Bitterness Units, or IBU. Budweiser falls at the bottom of the scale, at around 12, while Sierra Nevada’s Pale Ale ranks at 35 and most IPAs fall between 60 and 80.

That mouth-wrenching Tongue Buckler Imperial Red I mentioned? It was a 107.

Making Beer Milky: Ballast Point and most other breweries add extra carbonation to their beers. About a third of Ballast Point’s carbonation comes from the carbon dioxide produced by the last gasps of fermentation after the beer is bottled, but they use special carbon dioxide-producing stones to add in the other half to two-thirds of bubbly.

Beer served “on nitro” means it’s stored in a keg pressured with a mixture of gases, usually about 75 percent nitrogen gas and 25 percent carbon dioxide. The nitrogen gas keeps the carbon dioxide from completely carbonating the beer, producing that flatter and creamier head you see with drinks like Guinness and Ballast’s Black Marlin Porter.

Ballast Point also puts a shot of liquid nitrogen into its bottled beer, making for a creamier pour at home.

The Science of Brewing tour probably won’t be as science-heavy as most of the festival’s other events, and definitely won’t help with the event’s mission to encourage science, technology, engineering and math education for children. But the tour did make me more aware of the complicated brewing process and the technology local breweries use to make their beers taste certain ways. And the next time I’m confronted with a pint or bottle, I will remember Cherney’s scientific explanation of how exactly that beer came to be.

Now, if only someone could explain to me the science of beer goggles.

Please contact Claire Trageser directly at and follow her on Twitter:

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