Mash Temps & Efficiency
Mashing is a brewing term for steeping. The grain is hydrated and activates the malt enzymes and converts the starches into fermentable sugars. Different temperatures will result in different outcomes and flavor profiles of the final beer.
The chart below shows what happens at various temps:
Enzyme: Phytase
Temp Range: 86-126°F
Preferred pH: 5.0-5.5
Function: Also called the “Acid Rest”, it used to be used to lower the mash’s pH. Simple water chemistry replaces this need.
Enzyme: Debranching
Temp Range: 95-113°F
Preferred pH: 5.0-5.8
Function: Increases the solubility of starches resulting in increased extraction for certain malts and breaks down the 1-6 links in starches.
Enzyme: Beta Glucanase
Temp Range: 95-113°F
Preferred pH: 4.5-5.5
Function: Working within the same temperature range as debranching, this enzyme is best at breaking down gums.
Enzyme: Peptidase
Temp Range: 113-131°F
Preferred pH: 4.6-5.3
Function: Breaks down smaller amino acid chains released by proteinase, but only works from the ends, releasing yeast nutrients such as Free Amino Nitrogen (FAN).
Enzyme: Protease
Temp Range: 113-131°F
Preferred pH: 4.6-5.3
Function: This is the “protein rest” which breaks up large proteins that form the protein haze.
Enzyme: Beta Amylase
Temp Range: 131-150°F
Preferred pH: 5.0-5.5
Function: The final enzymatic process involves the conversion of starches into dextrins and fermentable sugars. The starches must be gelatinized for this to take place. *Gelatinization occurs during mashing. It is the hydration of starch molecules. When exposed to hot water, starch granules swell and burst, losing their organized structure (think popcorn).
Enzyme: Alpha Amylase
Temp Range: 154-162°F
Preferred pH: 5.3-5.7
Function: Temperatures above 155°F favor this enzyme, producing dextrins, which is less fermentable and results in a fuller body.
Enzyme:
Temp Range: 168°F+
Preferred pH:
Function: Enzymic process halts and becomes destroyed
Sparging at higher temps
Why do we sparge at 168°F – 170°F? Sparge water will rinse the sugars from the grains easier; however, sparse water is usually cited at 168°F to 170°F because after 170°F the enzymic process stops and the tannins and other things in the grain husks become soluble enough to be rinsed into the wort.
Mashing at a low temp (146°F – 148°F)
Mashing low has a slower starch conversion rate but will yield more fermentable sugars, leaving the beer thin and dry. Leave the mash temp too low (below 146°F) for too long, then you run the risk of ending up with a “watery” beer. Extending the mash time (90 mins) will help with the slow conversion.
Mashing at high temps (152°F – 162°F)
Higher mashing temperatures produce longer sugars which are more difficult for the yeast to eat and convert to alcohol. More sugar will be left over after fermentation resulting in a more full-bodied beer with a higher final gravity (FG).
Experiment
Brulosophy experimented with the same grist mashed at two different temperatures: one high (161°F), one low (147°F). The higher temp beer resulted in a +0.009 SG difference between the two. The low mash temp beer had a calculated 4.4% ABV while the high mash temp beer clocked in at a much lower 3.4% ABV. Higher mash temps are preferred for those who prefer making flavorful examples of big beers with lower amounts of alcohol.