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Posted by Chris Colby on Monday, 01 October 2012 in BYO Brew Blog

I love biology. One of my undergraduate majors was biology and I have a PhD in biology. If you really understand the subject, it gives you a perspective on life different from most people’s. For example, most biology majors end up taking either a parasitology or an epidemiology course for their undergrad degree. And slowly, as the semester progresses, you are transformed from a happy, well-adjusted human into a Howard Hughes-like recluse, afraid that all your food is teeming with worms and every door handle is a germ-smeared death sentence. (Ah, the memories!)

But eventually you get over it, rediscover sushi and get on your life. And if your life includes brewing, you have some absorbed some information that can help you become a better brewer. I believe one of the biggest benefits of having a biology background is a simple thing — understanding how small bacteria are.

Bacteria are small. Most are just a couple microns across. Brewers yeast cells, which are also small enough to be microscopic, are about 10 times larger than all the standard wort-spoiling or beer-spoiling bacteria. With 40X magnification, you can see yeast cells fairly well with a light microscope. (If the cells are not stained, turn the back lighting way down.) With 100X magnification (the next highest power on most light microscopes), most (stained) bacteria look only slightly bigger than a dot.

Now, just for some scale, let’s compare this to a speck of dust. We’ve all been in a room with a ray of sunshine coming in from a window and we’ve all seen specks of dust floating in the air. The size of dust particles depends on what the dust is made of, but if they are big enough to be visible, but small enough to stay aloft in a mostly still room, they are probably between 50 and a 100 microns — i.e. 10 to 20 times larger than bacteria.

There are many ways that bacteria can come in contact with wort or beer. Bacteria can come from unsanitized surfaces. They can also be introduced with the pitching yeast. Most major problems with contaminated beer probably come from these two sources. But one thing you can be sure of, your wort is going to be contaminated with airborne bacteria.

I’m not saying this to be defeatist. Everyone’s beer -- homemade or commercial -- has some degree of airborne contamination.

So what to do about it as a homebrewer? Well, just as you’ll eventually get back to eating sushi after taking a parasitology course, you’ll get over worrying about the fact that your wort is inevitably contaminated and begin to take steps to keep the level manageable. I would suggest a couple things. During your brewday (and especially when wort or beer may be exposed to the air), assume that you are walking around in a mist of bacteria. (You are, even in environments that are very clean by ordinary standards.) Based on this, take these four precautions:

If your wort is exposed to air, you should cover it with a sanitary cover. (For example, if I’m bottling, I’ll cover the top of the bottling bucket with sanitized aluminum foil.) You should minimize the amount of time your wort (or beer) is exposed to the air. (Don’t rush, but don’t let it sit exposed for longer than necessary.) Clean your environment of things that may harbor bacteria or wild yeast (esp. food). And finally, pitch a lot of yeast. A small amount of contamination (of the size that is inevitable from airborne sources) is easily undone by getting a quick start to your fermentation. With a good pitch, the bacteria should be vastly outnumbered and will quickly perish (or go dormant) from the rising alcohol levels and falling pH.

Now, did you know that Taenia solium, a cestode (tapeworm) that parasitizes pigs can get in your brain and eat it? It can. Enjoy your next pork chop.

Last modified on Friday, 08 March 2013

Chris Colby

I learned to brew beer right around the same time that I discovered good beer. I started graduate school at Boston University in 1990 and quickly began enjoying the local brews — particularly Harpoon Ale, Sam Adams Boston Ale and Dock Street Amber (from Philadelphia) — that were popping up. There was even a brewpub, Commonwealth Brewing, with three or four regular brews and a new “seasonal” beer every other month or so. I also tried out imported beers, whenever possible. Coming from South Dakota, where Beck’s was an exotic import, this was an eye-opening experience.

A couple of graduate students in my department brewed beer and I was immediately intrigued. I learned the basic extract brewing method from them, but was hampered for a long time by substandard equipment — especially the lack of decent-sized brewpot — and having to brew in a small Boston apartment.

My early brewing efforts were also hampered by my lack of knowledge. As a graduate student in biology, I could have easily dug into the advanced homebrew literature at the time, but I figured I had enough things to study and just wanted a nice, easy hobby that ended up with me drinking beer. And, even though the stuff I made wasn’t great, it did get drunk on poker night with no complaints.

I got a nudge in the right direction from a friend of mine, John Weerts. I went to college with John and would see him over the holidays as my folks had moved to Kansas City, where he lived. I taught him how to brew on one of those occasions, but then he struck out on his own. He joined is local brewclub (Kansas City Bier Meisters), stepped up to all-grain brewing and started making some really good beer. Years later, he visited me in Boston and brought along a keg of rye beer, which was fantastic. I immediately knew I was missing out on something.

On my next stop at my local homebrewshop (The Modern Brewer), I bought every book they had, including George Fix’s “Principles of Brewing Science” and Greg Noonans “Brewing Lager Beer.” Armed with the knowledge from these books, a new brewpot, and a ridiculously cobbled together all-grain set-up, I brewed a mini-mash version of a porter recipe of mine. It was the best beer I had made so far.

Fast forward to today, and I still think that gaining the right knowledge is the most important step to brewing great beer. (My brewing set-up is still almost comically jury-rigged, but it works.) I have read a number of professional brewing texts (and recommend the two volume “Malting and Brewing Science” set by Briggs, Hough, Stevens and Young), keep track of many of the great homebrewing forums out there, and am a member of the Austin ZEALOTS homebrew club.

The best way to gain brewing knowledge, however, is to brew. And, I normally brew about 20 batches per year. In the 15 or so years I’ve been a homebrewer, I have brewed ales, lagers and sour beers. I have tried most of the common traditional brewing techniques and experimented with new techniques (including my reiterated mashing techniques). Although primarily an all-grain brewer, my interest in extract brewing has been rekindled due to new techniques (such as the extract late procedure) and I have recently experimented with ways to improve partial mashing (especially making dark beers with a partial mash procedure).