29 June 2015

On Fermentation

When we think about distilling, there's a tremendous romance with the equipment and process surrounding the actual act of distillation. Copper pot stills, perhaps a massive series of plates, cooling systems, boilers. And then there's the aging process, with a forest full of oak long since forged into barrels, at rest for months on end working away at the distillate to make it something more.

But before that, there's an even older art: Fermentation. The true mark of a craft distiller is the care taken at *every* step, including the creation of what we call the mash. From raw materials - otherwise bland agricultural products containing starches and sugars - we first make superfood for yeast. And I don't mean a light lunch... I mean a Smörgåsbord. Let's take a look at this important process, marking a few of the more important steps and their possible pitfalls.

Step 1: Clean behind the ears.

Any respectable brewer or homebrewer knows the merits of cleaning. Whether it's a small cook pot with a five-gallon HDPE fermentation bucket or a 50BBL mash tun, removing all bacteria (or even wild yeast strains) that will compete with or attack your yeast is the starting point. This includes bacteria on/in any vessel which touches the mash, as well as residue on unwashed grains. You can't get it all, that shouldn't be the goal; but starting as purely as possible will only help a few steps down the road.

Step 2: Better ingredients, better... everything else.

The proportioned list of ingredients in a mash - the "mash bill" - is critical. It's the quasi-secret recipe of every mashmaster or stillmaster, finding balance between ingredients. That recipe guides us in cooking up something that will mature in good time into the beer- or wine-like mash that goes into our stills. And those ingredients didn't exactly get routed to you instead of a hog feeder - they're genuinely good foodstuff. Of course, your mash bill could be simple. Like, "1. Corn. 2. Water. End of list." Or even maple syrup. To be frank, I for one am totally spoiled by the simplicity of the latter at Black Squirrel. Oh, and one last thing: use filtered water in your mash. Because it's purer and tastes better? Yeah, sure. But also because if you have *unfiltered* water, that extra non-water mass takes energy to heat down the road... and probably won't be on the buffet for the yeast. Be a farmer for a few days.

Step 3: It's aliiiiive.... IT'S ALIIIIIIIIIIVE. (Until it's not.)

So you have your mash all mixed, and it's time to pitch the yeast. Almost done, right? Yes! Oh, except for that part where you need to keep that colony alive for the duration. You also must decide whether that's stopped at some point to harvest the ethanol, or if you let the mash ferment until the ethanol in solution kills the rest of the yeast population. Factors to measure along the way include pH, alcohol density, sugar density, core temperature, and anything else you can measure every day on your bench.

I've had conversations with people who like the idea of using a "turboyeast" to really kickstart the process, or even throwing in additives including "distiller salts" (nitrogen, like a fertilizer) to give their yeast performance a lift. Remember that last bit where you became a farmer? Good, now become a chemist. Think about whether you've added *up to exactly* what the yeast will go through - extra nitrogen is what I call a "VERY BAD THING" (technical term), especially if you're using copper. (Google up "cuprammonium hydroxide" for a while and learn what reagent you could be making instead of potable distillate.)

Step 4: "Here, smell this."

If you wouldn't / can't drink what you fermented, it's probably not good. Seriously. If you have an otherwise non-potable substance on your hands, don't go inflicting it on anybody. Yes, yes, yes, "It all comes out in the distillation! And then I filter it!," for crying out loud, yes. But you're never taking ONLY the alcohol out, are you? That hydrometer would have to be floating at 100% *all the time*... It doesn't happen. So pitch the nasty lot of mash, save yourself a headache. Also consider whether you let the fermented mash sit once it was biologically done - proteins are great at a barbecue, awful in a boiler if you've let the whole shebang rot.


So I think we've made a point here: distilling and aging ARE sexier than fermentation. It's just so much work. But when done right, the meeting of art and hard science can yield incomparable results, and it's what we're doing every day back in the Lab at Black Squirrel Distillery.


Sigh. The lawyers made me say the following bit: 

"Distilling at home or without a permit is illegal and would constitute a few felonies if done outside the law. Please seek appropriate licensure before distilling or fermenting with the intent to distill."