Mashing In

For the All Grain Brewer, Mashing is one of the most important steps during a brew day.  This step can have a broad effect on the finished beer depending on the mash and its temperature, length, and consistency.  The good news is mashing at its core is simple; add grain heat between 140 F and 160 F and your good.  The devil is in the details. 

Mashing can involve a number of different steps or “rests”.  Each of these rests has a different effect on the grain and the components that make it up.  Over the course of these rests the mashing process activates enzymes which break down proteins and starches in to soluble fermentable sugars ideal for yeast.  Additionally unfermentable dextrins are created which add to body.  Controlling the mix of these sugars and proteins is essential to making the beer you are targeting.

The following list describes each possible step or rest in the mashing process.  The only essential step is the saccharification rest.  All other rests are generally not necessary with today’s highly modified malts and can be used as required depending mostly on the type of beer targeted and malts being used.

Acid Rest

This step occurs when you add the grain to the strike water at a temperature between 95 F and 120 F for 1-2 hours.  The purpose of this step is to increase the acidity of the mash.  This is generally done only with grists high in adjuncts and under modified malts and low in dark malts.  This step can also assist in reducing the likelihood of a stuck sparge as it breaks down the cell walls in under modified malts.

Protein Rest

This step occurs when you add the grain to the strike water at a temperature between 115 F and 130 F for 15-30 minutes.  This step assists in breaking down proteins in the malt further than normal.  It is ideally used in under modified malts.  This step is not needed if you are using highly modified malts.  A Protein rest also helps to increase head retention and improve yeast health by pulling additional nutrients from the malt that contribute to a healthy fermentation.

Saccharification Rest

This step occurs when you add the grain to the strike water at a temperature between 140 F and 160 F for 30-90 minutes.  This step is required and directly affects the end product.  There are two different enzymes used during this step and each is activated at a different temperature range.  Beta Amylase is the enzyme most active below 150 F.  This is the ideal range if you are making a light bodied beer as it produces a more fermentable wort with less unfermentable dextrins.  Alpha Amylase is the enzyme most active above 150 F and is ideal for full bodied beer as it produces a less fermentable wort with more unfermentable dextrins.   

Mash Out   

The mash out process occurs after the Saccharification rest and is ideally conducted at a temperature of 168 F to 172 F for 10-15 minutes.  Be careful not to go over 172 F as it will leach undesirable tannins from the grains giving your end beer an astringent taste.  The mash out process denatures the enzymes and stops the conversion process leaving you with the end wort made up of the ideal mix of fermentable and unfermentable sugars.  You may now start the sparge and boil process.

A note on temperature; it is ideal to hold the temperature a close as possible to the target temperature to ensure the correct enzymes are active and producing the desired mix.  You can use a cooler, a RIMS system, HERMS system, or directly fire your mash tun.  A good cooler can hold temperature with in 2-5 degrees F which is acceptable.  The other options can be far more precise; especially RIMS and HERMS but require a more sophisticated system.

If you’d like more homebrew information, follow me on twitter @Tom_Ayers.  If you have any questions, comments, or topic requests send me an email at AyersBrewing@gmail.com and I’ll be sure to respond.  Until next week, cheers and happy brewing!