The other weekend I brewed up my first ten gallon all-grain batch. For the uninitiated, homebrewers typically start by using malt extract, where the sugars for the yeast are extracted, condensed into either liquid or powder form, and then sold. Most that stick with the hobby eventually move to all-grain, where you use the actual grains of malted barley and extract the sugars yourself. It's a bit more labor intensive, and definitely more equipment intensive, but it gives you more control over your flavors and gives you an excuse to play with more toys.
I called over a buddy who also brews, and we got started at about 10AM. We were doing an American Pale. Since we were doing ten gallons, we decided to split the batch between us and use a different strain of yeast on each half. This way the process, the grain bill, the hops, the fermentation... everything about the beers would be identical except the yeast, so any differences between them we could attribute 100% to that. Fun little experiment.
To get the sugars out of the malted barley, you have to soak it in water of a specific temperature. This process is called mashing, and takes place in the mash tun. Mashing activates enzymes that convert the starches in the grain into starches that the yeast can eat. Different temperatures activate different enzymes, but the range is pretty narrow. Below 146 or so you won't convert enough of the sugars and get a beer with really low alcohol and really high sweetness; above 156 or so you'll get really high astringency and a bad, puckery beer.
Coolers make great mash tuns because they generally hold a temperature well. Here is a picture of my empty mash tun cooler, a 100 qt. monster.
For the batch, we had 26 pounds of grain and needed to mash with 8 gallons of water. We wanted to mash at 152F, so we needed to heat our water to about 168F. Once the 168F water hit the grains and cooler and was all mixed, it should come out to 152. Here is my 15 gallon brew pot.
It's on a propane burner. The stove just doesn't cut it for bringing 15 gallons of liquid to a boil. Once we had 8 gallons up to 168, we dumped it in the cooler, and then dumped in the grain. This is mashing in, and my friend handled the grain while I stirred. It's important to get all of the grain wet, since if it stays dry, the sugars won't convert.
If you've ever done a brewery tour or been upqind of a brewery, that smell that hits your nose is the mash, more or less. I think it smells delicious, but my gf doesn't, which is one more reason I brew outside. Since this was my first time both brewing ten gallons and using my mash tun, I wasn't sure how things would go. Specifically, I wasn't sure how much temperature the cooler would absorb, how well it would hold heat, etc, and like I said, that stuff is pretty important. After mash in, our mash was 148. Since we wanted 152, that was on the very low end of acceptable. We added a few quarts of boiling water and got it up to 150 and stopped there and called it good.
The enzymes take a while to do their work, so we let the mash sit for an hour. Time for a beer!
That's Sierra Nevada's Southern Hemisphere fresh hop beer, the counterpart to their fall fresh hop offering. It was good, but from memory I liked the other one better.
After the hour-long mash, it was time to drain the liquid from the mash tun. The water we combined with the grain has become infused with all those delicious sugars and is really sweet at this point. The first time you drain that liquid out is called the first runnings. For this batch, we would drain the mash tun once, fill it back up with more water, and drain it again to collect as much of the sugar as we could.
When the mash tun is drained, the grain compacts and looks like this:
Spent grain is good for all sorts of stuff. Farmers use it for feed. I use it to make dog biscuits for my dogs.
We were aiming for about 14 gallons of sweet liquor in the brewpot. After evaporation during the boil, the hops absorbing some, and various coagulated proteins and junk floating around, we hoped that would give us 11 gallons to ferment. Getting all that up to a boil took about 20 minutes, and then it was time to add the hops. Here's 1.5oz of Simcoe hops, in a hop bag, just after addition.
The next hop addition wasn't for another 50 minutes, and things look more or less the same:
One final hop addition ten minutes later, and it was time to turn off the burner and cool things off. The liquid - aka wort - should be cooled as quickly as possible. When it's boiling, nothing can live in there, and when it's sealed up, nothing can get in, but in between, all that warm, sweet, sugar-laden wort is a haven for bacteria. We cooled it with an immersion chiller. That's a coil that you immerse in your wort and run cold water through.
To cool things down even more quickly, once the wort got down to 90F or so, we hooked up a second immersion chiller and put it in an ice bath, so the water went through the ice, then into the boil kettle. The setup looks gangly, and it was, but it's sort of arranged left to right, with that bucket in the left foreground being the ice bath.
Once the wort is nice and cool, it's time to transfer it into the fermenter and add the yeast. I've got the fermenters in my kegerator/fermentation chamber, holding at a nice 67F. Fermentation temps are just as important as mash temps, so having a way to regulate how hot it ferments is really nice.