During our 12/17/11 meeting, club VP Nick discussed decoction mashing. Here are the notes:

• Hardest type of mashing. Mainly for German style beers, (Marzen, Pilsner, Maibock) as it was the process they traditionally followed with their brewing techniques.
• The general idea involves getting mash to certain temp, pulling a portion of grains out, boiling those on the side. Those grains are then added back to mash to achieve goal temperature.
• The three steps regard three different temperatures for the following reasons: Acid rest, Protein rest, Sacchrification steps (135 – Beta rest); 150-162 Alpha rest)
• Why use a decoction mash?: If you have an under modified malt. Not needed for typical malts available in LHBS.
• “Moderately Modified” sugars and proteins available (Belgian, UK, International Pilsners)
• Goal: Malty character: ie Pilsners, Bochs, Wiesens, Malts.
• Boiling grains – creates melanoidins (extra maltiness)
• How: traditionally: 3 steps
  • Mash in grains @ 95 F
  • Acid rest, pull out 1/3 of mash (pull out thick portion – sans water) Enzymes are soluble in the water, boiling denatures them.
  • Boil ~15 min using water already absorbed into grains, (stirring constantly) add in, get temp to protein rest (115-130F) – Allows for specific enzymes to act on grains (peptidase, protease- to break down proteins) – Breaking down proteins creates crystal clear beer
  • Bring to Sachrification rest (150-154), pull out another decotion, mash out at 168. Then sparge
  • Takes ~3 hours for a typical 1 hour mash
• In practice, Nick has done this:
  • 2-step: (Maibock) 154 F water added to get to 133 F. Very end of the protein rest range.
  • Pulled out 1/3 mash, protein rest is only for 20 min max – or you lose head (protein is the source of “cling factor” when the final product is poured into a glass)
  • Bring back to 154
  • Pull out one more decoction, mash out, sparge.
  • 2-step is 1-1.5 hours
• Nick’s Advice: Pull more grains out than you think you need.
• During the last decoction boil more liquid to grain. Otherwise other starches may create haziness, affect flavor.