The American Homebrewer's Association (AHA) decrees that the first Saturday of every November is Learn To Homebrew Day. This year that day fell on November 7th, so ALES members Jeff and myself (Joel) brewed a couple batches of beer. Jeff decided to brew an IPA from a recipe he obtained from the book 'Clone Brews'. Myself, I decided to go a little extreme and brew a Maple Sweet Potato Saison (recipe here). I've never brewed with potatoes before (or any other starchy adjunct for that matter) so it was a learning experience for me as well.
Mashing In
Mashing in is the process of adding hot water (Strike Water) to the milled grains and having the whole mixture come to rest at a specific temperature. For a single infusion mash (which is what both Jeff and I were doing), your mash-in temperature is your starch conversion temperature. There are a few variables to understand about the mash, but it's characteristics are mainly formed by two things - the mash thickness and the temperature. To measure mash thickness we use a ratio of water to grain. A 'thin' mash of two or more quarts of water to 1 pound of grain (or 4.15 Litres per Kg) will produce wort that is more fermentable, whereas a 'thick' mash of 1 quart of water to 1 pound of grain (2.08 L/Kg) will produce a more full and sweeter wort (less fermentable). For starters a good balance is about 1.25 quarts per pound of grain (2.6 L/Kg).
The next major variable is the temperature. Starch conversion is the act of enzymes in the malt converting the starch in the grain to sugars. Without the sugars, the yeast would have nothing to ferment and we'd have no beer. So you can see this step is kind of important. Enzymes tend to work better at certain temperatures than others, and for starch conversion, the best temperatures tend to be between 145F and 160F (62.7C to 71C). The lower you are in the temperature range, the more fermentable the wort will be, likewise, the higher the temp, the less fermentable the wort will be. Generally speaking, most beers can be mashed between 150F and 155F with good results (65C to 68C).
For my Saison I had 7.5 Kg of grain including the rice hulls (16.5 lbs). I use a standard water to grain ratio of 1.25 qts/lb (2.6 L/Kg) so the amount of strike water I needed was 19.5 Litres (5.15 gallons). That's the easy part. Figuring out what temperature the water should be at before I mix it with the grain is a little trickier. There are equations that you could use to figure this out, but this is why brewing software was invented. There are many different programs out there, so if you don't already use one, I would encourage you to try some out and find one you like. I use BeerTools Pro, but other popular programs include ProMash, BeerSmith, BeerAlchemy, StrangeBrew and I'm sure many others. Plugging my desired mash temperature (65C) into the software told me that my 19.5L of strike water should be heated to 74.2C before it is added to the grain. The software even takes into account the temperature outside which I estimated to be about 5C.
Even with all these calculations, this number is still a best guess or estimate. Generally speaking, I like to heat my strike water up a few more degrees than what the software predicts, mash in, let the temperature stabilize, and then add cold water if needed to get down to where I want to be. It's much easier to bring the temperature of your mash down than to bring it up.
Mashing
This is the easy part - at least in a single infusion mash. Once you've mashed in and hit your desired temperature, you wait. The enzymes will do there work and convert all the starches to sugars. How long this takes depends on a couple of factors, but to put it simply, if you are making a more fermentable wort (thin and/or low end of temperature range), it will take longer than if you are making a less fermentable wort (thicker and/or higher end of temperature range). Myself, I like to leave the mash for at least an hour, and up to 90 minutes if I am making a dry, fermentable beer. In the case of the saison, I left it for 90 mins. There is an starch conversion test you can do with some Iodine (Iodophor will work as well), but I've never been real confident with it.
Sparging
Once the mash is fully converted it is time to get the wort out of it. There are two main ways of sparging, fly sparging and batch sparging. With fly sparging, you trickle hot water over the top of the mash at the same time as you draw off sweet wort from the bottom and thus rinse the grain. This is the traditional way of brewing and the way that commercial brewers operate. The drawbacks to this method is that you require a two or three tier set up with your hot liquor tank above your mash tun or you need pumps to pump the sparge water over the mash. I have neither a three tier setup or any pumps, so I batch sparge.
Batch sparging involves draining off the sweet wort from the mash, adding hot water back to the mash, letting it sit for a few minutes at which point it is drawn off again. This process can be repeated 2 or 3 times to get as much sugars out of the grain as possible. With my saison I batch sparged by first adding 8 L of sparge water (temperature of which is 76C or 168F). The mash was then drained, slowly at first, collecting the first cloudy runnings which were pour back into the top of the mash, then after the wort started to run clear, it was drained as fast as my 1/2" valve would allow. After the first sparge, 8 more litres of sparge water were added, I waited for 15 mins, then repeated the draining process again. After all of that 30 L of pre-boil wort was collected.
Boiling
The act of boiling the wort serves a couple of purposes. First it kills any bacteria in the water or wort and denatures any enzymes to stop them from doing anything further. It also isomerizes alpha acids from hops to give the beer bitterness. It coagulates proteins and leads to a more stable and clearer beer. Lastly it can concentrate the wort by boiling off water (leaving a 'stronger' sugar solution) and add flavour from carmelization. Typically wort is boiled for 60 to 90 mins. For all-grain brewers, I would recommend boiling for 90 mins, as boiling drives off some unwanted chemicals found in some malts, namely DMS, than can lend a cooked corn flavour to your finished beer. You should always boil uncovered for the same reason.
As the wort begins to boil, make sure you watch it carefully. As the proteins begin to coagulate the wort will foam up and want to boil over. You can prevent this by backing off the heat, spraying the foam with a spray bottle filled with water, or just let is overflow and get all over the ground (I hope you are brewing outside!). After 10 to 15 minutes of careful boiling, the proteins should be coagulated, and boil overs will not happen any more. This is when I add hops and start my timings. For my saison, I boiled for 90 minutes with 2 hop additions. 18 g of Nugget hops with 60 minutes left in the boil for bitterness and 20 g of Goldings hops with 5 minutes left in the boil for some aroma and flavour.
Chilling
After boiling the wort the next step is to get the wort down to yeast pitching temperatures (20C or lower) as quickly as possible. There are many ways to do this, but the most effective way is with a wort chiller. They come in two basic varieties, immersion and counterflow/plate. An immersion chiller is a coil of copper tubing that you submerse in your hot wort and run cool water through it. It will transfer the heat from the wort to the water running through the coil, cooling the wort. Obviously , the more copper coil you can put in your wort, the more effective it will be. The other type of chiller is a type where cold water and hot wort are allowed to flow past each other separated by metal that transfers heat easily (like copper or stainless steel). These 'counterflow' chillers are more efficient but are generally tougher to build at home, and commercially more expensive (but not unreasonable). In my opinion, this is one piece of equipment it doesn't pay to scrimp on. Get the best chiller you can afford and take care of it. I use a plate chiller that can chill the wort as fast as I can run it out of the kettle into the carboy. It saves time and decreases the risk of infection and bad beer.
Fermentation
Once that wort is chilled down, pitch that yeast, oxygenate the wort either by shaking or using a diffusion stone with an aquarium pump (and filter) or with pure oxygen. You'll only have to wait a few weeks to enjoy the fruits of your labour and boy is it worth it!
Further Reading
For a great primer on all grain brewing (or homebrewing in general) check out John Palmer's book How To Brew which is available online.
