Chapter 17 - Getting the Wort Out (Lautering)
Aspects of Lautering
Okay, let's see where we are: we have discussed the different types of grain and how they can be used, we have talked about the mash enzymes and how they are affected by temperature and pH, and we have learned how the brewing water and grainbill combine to determine the mash pH and how we can manipulate it. In the last chapter, we moved from the chemical aspects of the mash to the physical. We learned about the several basic methods of conducting a mash and producing the wort. In this chapter, we are going to discuss how we separate the malt sugars from the grain.
Lautering is the method most brewers use to separate the sweet wort from the mash. A lauter tun consists of a large vessel to hold the mash and a false bottom or manifold to allow the wort to drain out and leave the grain behind. Lautering can be conducted several ways, but it usually consists of 3 steps. These are: mashout, recirculation, and sparging
What is Mashout?
Before the sweet wort is drained from the mash and the grain is rinsed (sparged) of the residual sugars, many brewers perform a mashout. Mashout is the term for raising the temperature of the mash to 170°F prior to lautering. This step stops all of the enzyme action (preserving your fermentable sugar profile) and makes the grainbed and wort more fluid. For most mashes with a ratio of 1.5-2 quarts of water per pound of grain, the mashout is not needed. The grainbed will be loose enough to flow well. For a thicker mash, or a mash composed of more than 25% of wheat or oats, a mashout may be needed to prevent a Set Mash/Stuck Sparge. This is when the grain bed plugs up and no liquid will flow through it. A mashout helps prevent this by making the sugars more fluid; like the difference between warm and cold honey. The mashout step can be done using external heat or by adding hot water according to the multi-rest infusion calculations. (See chapter 16.) A lot of homebrewers tend to skip the mashout step for most mashes with no consequences.
What is Recirculation?
After the grain bed has settled and is ready to be lautered, the first few quarts of wort are drawn out through the drain of the lauter tun and poured back in on top of the grainbed. The first few quarts are almost always cloudy with proteins and grain debris and this step filters out the undesired material from getting in your boiling pot. The wort should clear fairly quickly. After the worts starts running clear (it will be dark and a little bit cloudy), you are ready to collect the wort and sparge the grainbed. Re-circulation may be necessary anytime the grain bed is disturbed and bits of grain and husk appear in the runoff.
What is Sparging?
Sparging is the rinsing of the grain bed to extract as much of the sugars from the grain as possible without extracting mouth-puckering tannins from the grain husks. Typically, 1.5 times as much water is used for sparging as for mashing (e.g., 8 lbs. malt at 2 qt./lb. = 4 gallon mash, so 6 gallons of sparge water). The temperature of the sparge water is important. The water should be no more than 170°F, as husk tannins become more soluble above this temperature, depending on wort pH. This could lead to astringency in the beer.
The wort should be drained slowly to obtain the best extraction. Sparge time varies depending on the amount of grain and the lautering system, .5 - 2.5 hours. Sparging means "to sprinkle" and this explains why you may have seen or heard discussion of "sparge arms" or sprinklers over the grain bed for lautering. There is no reason to fool with such things. There are three main methods of sparging: English, batch and continuous.
In the English method of sparging, the wort is completely drained from the grain bed before more water is added for a second mash and drained again. These worts are then combined. Alternatively, the first and second runnings are often used to make separate beers. The second running is lighter in gravity and was traditionally used for making a Small Beer, a lighter bodied, low alcohol beer suitable for high volume quaffing at mealtimes.
Batch Sparging is a U.S. homebrewing practice where the full volume of sparge water is mixed into the mash. The grain bed is allowed to settle, and then the wort is drained off. The re-circulation step in this process takes place in the first minutes of the sparge. You can use more than one batch of water if you need to. This method differs from the English method in that the mash is not held for any significant time at the saccharification temperature before draining.
Continuous Sparging usually results in better extractions. The wort is re-circulated and drained until about an inch of wort remains above the grain bed. The sparge water is gently added, as necessary, to keep the fluid at least at that level. The goal is to gradually replace the wort with the water, stopping the sparge when the gravity is 1.008 or when enough wort has been collected, whichever comes first. This method demands more attention by the brewer, but can produce a higher yield.