Mashing can be a mystical process for first time all-grain or partial mash beer brewers. At its heart, the mashing process uses hot water and natural enzymes to convert complex sugars from malt into simpler sugars that can be readily fermented. We covered the basics of infusion mashing in an earlier article.
At its essence, mashing converts long chains of starches into much shorter sugar chains. Several enzymes that naturally occur in barley malt play key roles in breaking down these sugars. The process starts during malting when the barley grains are germinated and dried. Beta-glucanese and proteolytic enzymes divide branches of complex sugars into shorter chains.
During the mash, the heavy lifting is done by diastatic enzymes that break down the protein and carbohydrate chains that lock up fermentable sugars. Further, as these starches are heated they become more soluble in water, making it possible to extract the sugars and create the sweet wort extracted during lautering. Crushing the grain before mashing increases solubility making it possible to extract a larger percentage of the sugars and starch.
Here’s a summary of the major enzyme groups found naturally in malted barley and their active range:
- Phytase (86-126 F) – Lowers the pH of the mash. Lowering the mash pH has a number of benefits, though a Phytase rest is rarely used by modern brewers.
- Debranching (95-112 F) – Helps to increase the solubility of starches resulting in increased extraction for certain malts.
- Beta Glucanese (95-113F) – Breaks down the gummy heavy starches, which can help improve stability and extraction, particularly for mashes high in proteins and adjuncts such as wheat.
- Pepidase (113-131F) – Produces free amino nitrogen, which can aid in fermentation.
- Beta Amylase (131-150F) – Produces maltose, the main sugar fermented in beer.
- Alpha Amylase (154-162F) – Produces a variety of sugars, including maltose and also some unfermentable sugars. Mashing at the higher end of this range produces more unfermentables and therefore more body in the finished beer.
For single or multi-step mashes, the main step is called the conversion or saccrification step. The bulk work of mashing is done by the alpha and beta amalyse enzymes, both of which are active to some degree in the normal 148-158F conversion step range.
Mashing at a lower temperature of 148-152F activated more beta amalyse, resulting in more maltose conversion. Maltose is the primary sugar preferred by yeast, so a lower mash temperature results in a larger percentage of sugars being fermented resulting in a clean beer finish with higher attenuation, slightly higher alcohol content and less body overall. It does generally take a bit longer for beta amalyse to do its work, so a longer conversion step at low temperature is needed.
Mashing at the high end of the range (154-158F) activates alpha amalyse, resulting in not only maltose but other unfermentable sugars. Less of the sugars will ferment, leaving lower yeast attenuation and additional body in the finished beer. Alpha amalyse completes its work more quickly than beta, so a slightly shorter step time can be used.
The other popular step used by modern brewers is the dough-in rest (protein rest). Usually done at a temperature between 100-120 F, the dough in allows the grains to soak and saturate as well as allowing the key various lower temperature enzymes to begin chopping up longer chains of molecules. This will generally lower your pH slightly, and improve your mash efficiency by a few percent. I personally recommend a 20 minute dough in at a temperature between 100-112F for maximum impact.
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