I bottled my most recent batch of homebrew today. The largest part of bottling day is cleaning and sanitizing. It seems that a lot of brewing is those two things. And it's true. Once the floor has been swept, the counter has been cleaned, the equipment has been sanitized and everything's had time to dry, you finally get to start on the first step of actually bottling. For me that means transferring from the secondary fermenter to a bottling bucket. Seems like a pretty innocuous task that wouldn't spur debate in any way, but this thread on Homebrew Talk went on for a good month, sometime quite heatedly, refuting one word in that last sentence. Secondary. It all stems from the evolving nature of common knowledge.
Secondary fermentation probably goes back to the days when open fermentation was common. When the yeast are highly active and producing a lot of CO2, the layer of gas protects the beer from any oxygen that could get in and cause problems. Yes the airlocks we all put on our primaries are a little redundant, but when it comes to five or ten gallons of delicious liquid bread, can you really be too safe? Anyway, when yeast activity slows, the chances of oxygen getting in rises, so everything needs to be kept somewhere with no exposure. Basically the primary would act as an aerobic fermentation while the secondary acted as an anaerobic fermentation. Of course this practice is a bit anachronistic when you factor in modern home brewing equipment wherein the only aerobic difference between the two is the amount of headspace. So the primary starts out with more oxygen but it's still a closed system.
Faced with its own impending obsolescence, this is where secondary fermentation blurred the line between itself and lagering, the practice of storing beer at cooler temperatures. The case for secondary fermentation was made by claiming it produced a clearer drink. Which makes sense when you take into account that the most famous lagers styles are incredibly clear. It was also claimed that the carcasses of the previously vibrant yeast would decompose and impart off flavors. This is called autolysis and is often thought of as yeast cannibalism even though such an act is physically impossible. It's less like chewing off your limbs and more like stomach acid spilling out onto your other organs. However, as you see from the previously mentioned Homebrew Talk thread, many brewers have found that if you skip the secondary, the yeast will take care of any negatives associated with this macabre process for quite some time and ultimately produce a better tasting beer. Plus, it saves you time and sanitizer while reducing the risk for contamination. Win win win!
So what do I do? I'd like to experiment with a long primary but I'm ultimately going with racking to a secondary. But with all these reasons not to, why? My answer is one word. Acetaldehyde. This chemical compound, also known as CH3CHO, is produced by our bodies naturally when we drink alcohol. But just because our bodies make it doesn't mean they like it. It comes from breaking down ethanol and is immediately turned into acetic acid. When your liver can't keep up, that's when you get a hangover. Getting the wort off the lees, you avoid adding extra acetaldehyde to the eventual beer. Okay, beer with less hangoverage, is it really worth it? No. But acetaldehyde doesn't stop with hangovers. The pesky little compound happens to be a known carcinogen. It also damages DNA directly and has been found to boost the addictiveness of nicotine. I'm all for mitigating its prevalence!
Of course you might say I'm being a bit too cautious by letting this sway my decision, but you still put that airlock on your primary.
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