Okay, so you’ve mastered starch conversion: your grist is milled to perfection, you’ve broken down all the clumps of dry grain, and the enzymes have done their job transforming that grain into malt sugars. Now, it’s time to sparge and collect the wort. Your lautering efficiency will determine how much sugar you can rinse from the grain bed.
Lautering Efficiency
As with starch conversion, you will find it worthwhile to understand exactly what’s going on with your lautering efficiency. The mash tun is a big matrix of wet, spent grain, full of dissolved sugars. As you sparge, the incoming water carries the dissolved sugars into the brew kettle. Depending on the temperature, conversion may still be taking place, breaking long-chain dextrins into shorter, more fermentable sugars. Many brewers do a formal mash out (raising the mash to 170°F/77°C for 10 minutes or so), or they sparge at a higher temperature to control this process.
The goal is to collect as much wort as possible, but you will also need to avoid leaching tannins from the grain husks. Temperature is one factor to consider—very hot sparge water (higher than mash out temperatures) will extract tannins. But the pH is also important because sparge water is usually more alkaline than the mash, and as pH rises, tannins will wash out along with the sugars.