Performing a Turbid Mash
Here’s a simple turbid mash schedule for preparing a basic lambic wort from a grist containing about 30 to 40 percent unmalted raw wheat. The process assumes you’re making a 5-gallon batch.
PROTEIN REST
Mash in at 113°F (45°C), aiming for a water-to-grist ratio of 0.25 to 0.30 quart (236 to 284 milliliters) per pound. This is a very thick mash, but you will thin it with hot-water infusions to raise the temperature. Hold at this temperature for 10–20 minutes.
GELATINIZATION REST FOR RAW WHEAT
Add enough boiling water to raise the temperature of the mash to about 137°F (58°C) and hold for 10 minutes.
FIRST TURBID DRAW
Push your stuykmanden (colander) down into the grain bed and allow liquid to flow into it. The liquid will be cloudy but should be mostly particle-free. Draw off about a quart (946 ml) of cloudy liquid and place it in a separate medium pot or saucepan. Heat this liquid to about 180°F (82°C) and hold it there. This high temperature halts enzymatic activity in the turbid portion and prevents further conversion.
MAIN MASH BETA AMYLASE REST
Add more boiling water to the main mash to raise the temperature to 150°F (66°C) and hold for half an hour.
SECOND TURBID DRAW
After half an hour, repeat the colander procedure and draw about 4 quarts (3.8 liters) of liquid from the main mash. Add this to the pot with the first collection of turbid wort, and once again, add enough heat to maintain 180°F (82°C), again to prevent further conversion.
MAIN MASH ALPHA AMYLASE REST
Back at the main mash, add enough boiling water to raise the temperature of the mash to about 162°F (72°C) and hold for another half hour.
MASH OUT
Raise the temperature of the turbid wort to 185°F (85°C) and return it to the main mash. This should raise the temperature of the mash to your normal sparging temperature of about 168°F (76°C)—add more boiling water if necessary. This will halt enzymatic activity. Hold at this temperature for 5–10 minutes before lautering and sparging.
After the mash is complete, vorlauf, lauter, and sparge as you normally would, but sparge with water that is hotter than usual, about 190°F (88°C). A hot sparge is necessary to gelatinize starches in the raw wheat and carry them into the kettle. Collect your usual pre-boil volume and proceed as usual.
The resulting wort is going to be very cloudy, almost milky in opacity. But with time, as your souring bugs chomp away on all of those starches, the beer will clarify. In a year or more, you’ll have surprisingly clear lambic that may be enjoyed on its own or blended with older lambics to create gueuze.
