Wednesday, November 14, 2012

Decoction and Infusion in a world of limited mash tun volumes

If the Title didn't throw you, this blog post is sure to do the trick.  Since I brewed over the weekend, beer nerd is in full effect as I contemplate the wins and losses of the weekend of brewing.  Decoction and Infusion  are two different styles of mashing which is raising the temperature of and washing the sugar out of grain.  Infusion is the most straight forward to understand so I'll start there.  The basic premise is you have malted and crushed grain that you need to extract sugar from.  The malting process has made enzymes available to start acting on starches, milling the grain has freed the starches and enzymes from their husks and now we need to hit various temperatures for the enzymes to activate.  There's a good deal of science that will explain what happens at the various temperatures, but this chart is a handy enough reference for our purpose here.

The beer I brewed this weekend had a grain bill of 15 lbs, which is pretty big for the 10 gallon cooler that I use as a mash tun, if I followed the traditional proscription of 1.25 quarts/lb I would be an initial infusion of about 4.6 gallons at dough in, then added the second infusion of 2.7 gallons and the third of 2.7 gallons for a 104 - 140 - 158°F rest schedule, the water alone would be enough to overfill the cooler.  With grains added infusion mashing of adding boiling water to reach my rest temperatures was not possible with my equipment. So decoction was the only option that would work for my grain bill and equipment.  If I'm reading correctly the "proper" decoction method is done by removing a portion of the grains and boiling them and return it to the mash.  The method I used was somewhere between infusion and decoction in that I used the ball valve to draw off wort from the bottom (about 1/2 gallon at a time) to boil and return to the mash.

This method worked for my purposes and got me to about 75% efficiency (measured) which is probably the highest I've managed on any mix of equipment to date.  In the past I've mashed using my keggle as the mash tun and directly fired the mash to raise/maintain temperatures.  I like using the cooler because the mash stays within +/- 1°F of the temperature you put it in at making it much easier to hold temps for whatever the mash schedule is.  I'm reading a lot of different information about the rest schedule with opinions on the "ideal" time for each rest ranging greatly, from just 10 minutes up to 90!  I've followed a few different sites recommendations and the longer rests have just extended my brew day, but haven't improved my yields or flavor as far as I can tell.  I think that it will take a few more brews with my current equipment setup to get a real feel for it, but my current inclination is to stick with John Palmer's mash schedule and do my modified decoction process.  The only item I'm inclined to add to my process at this point in a true false bottom for my mash tun, as the stainless steel braid is annoying me.  it feels like towards the bottom half of draining the wort the tube gets plugged up and the flow the the wort slows considerably.  To counter this, I use my stirring paddle to kind of rub the hose and pull the grain away from it enough for the liquid to flow to the hose, which speeds up the flow considerably, but requires somewhat constant attention to get the mash tun completely drained.  From some reading on the matter the false bottom might not help with the thing that is truly bothering me, as I'm not doing the "sparge" correctly.  My problem is called a stuck sparge, but I'm not adding liquid to the top of the grain bed as I drain wort so I've been doing it wrong.
This kind of makes me feel like an idiot, but it also makes me confused.  What does one do with the water that you've now added to the grain while you drained?  You'll have 6 or so more gallons of very, very lightly sugary water to deal with.  I drained it and cooked it down but the wort was only 1.014 OG, and Palmer recommends you collect down to 1.008 or until you have collected enough wort.  With this about 5 gallons of low gravity wort you could cook it down on low heat, but your talking about a good deal of time to accomplish this task.

1 comment:

  1. wow, josh. i leave you alone for two seconds, and you start making your own booze...;)