Mashing Methods

Mashing, the original, age-old technique for converting starch to sugar, has been experimented with and refined much over the years. This ancient transformation of starchy to sugar has often seemed as magical as the fermentation itself, and mashing has many intricacies which can make the task interesting at many levels, from a microbiological level to the craft brewing level. Here I will discuss various techniques for mashing, including partial mash, fly sparging vs. batch sparging, infusion, decoction, step, and steeping.

Grain bag used in steep mashing

Partial Mash
A good place for homebrewers to start learning how to make all-grain brews. Partial mash brews utilize one of the many mashing techniques offered here, but with an additional sugar boost from malt extract to ensure that the beer will succeed, even if the mash does not. In essence, the malt extract is a product that does it all for you - the malting, mashing, and boiling down of the malt sugars is attained all in one purchase. Although some brewers use different sugary admixtures to achieve the specific gravity they are shooting for, such as honey, molasses, agave nectar, cane sugar, or some various combinations of those.

Steep Mash
This mashing technique can also be used in conjunction with partial mash brewing, but it is advisable to use this method only with certain types of grains, which lend themselves to it. Most homebrewers become familiar with steeping grains as a way to add a pleasant flavor to their malt extract based homebrew. Steep Mashing is more for flavor than starch to sugar conversion, but both aspects of this technique have their effect upon the flavor profile of the beer.

Fly Sparging vs. Batch Sparging
Fly sparging and Batch sparging are two different techniques used to accomplish the same goal. Sparging is the process of taking the hot water, called sparge water, after the mash, and pouring the hot liquid over the grains to extract as much malt sugar as possible from the grains. This process has a temperature restriction: it must be done at 167-176 degrees Fahrenheit. The sparging technique also changes the flavor of the wort, and is not used for every kind of beer.

Fly sparging, also known as continuous sparging, is the traditional technique of slowly adding the sparge water from a hot liquor tank evenly over the grains, while draining off the wort at the same time. The idea is to keep the same volume of liquid continuously in the sparging tun. It can be difficult to regulate the flow of wort evenly on both ends of the operation, and also to keep the temperature of the wort at a consistent 167-176 degrees Fahrenheit. It requires that there be a heat source under the lautering tun, as the slow trickle can take a long time to finish. Fly sparging allows for the thicker, sweeter wort to be collected apart from the thinner, less sweet solution. This method is clearly superior if you are interested in making a high gravity beer and then a small gravity beer (often referred to as 'small beer').

Batch sparging, on the other hand, is a simplified way to achieve a homogenous wort. With batch sparging, the lauter tun is filled up with water, stirred, and then wort is drained off and poured back into the top of the lauter tun for vorlaufing. After recirculation, the lauter tun is drained into the kettle for the boil. A second and/or third "batch" of sparge water is added to the mash and stirred. The wort is recirculated again and drained into the boil kettle. Batch sparging is much faster and can often be tooled more easily than fly sparging, and so a lot of home brewers are going this route.

An example of single infusion mashing

Infusion Mashing
There are a few different types of infusion techniques, including Single Infusion Mash, RIMS (Recirculating Infusion Mash System), and HERMS (Heat Exchange Recirculating Mash System) - the last two systems being dependent upon your ability to build or acquire a complicated technological brewing platform.

The Single Infusion Mash technique utilizes a simple insulated Igloo style cooler to act as a mashing tun. You can easily calculate the temperature of hot water that will be needed to facilitate mashing by using our strike water calculator. The idea is that the temperature of the water will be slightly higher than your target mashing temperature, in order to compensate for the pour into an unheated vessel.

RIMS (Recirculating Infusion Mash System) is a system that pumps the mash in the mash tun over a source of direct heat - usually a propane burner or heating element of some sort. The idea is that the wort will be continuously circulated over the heated area so that it does not become scorched. The heating element or propane burner is controlled by a temperature controller which senses the temperature of the mash. The propane style system is sometimes referred to as FART (Fire Actuated Recirculating Tun) .

HERMS (Heat Exchange Recirculating Mash System) is a similar build, but adds the element of using the hot mash water to heat up the water for the sparge via a wort chiller-style copper coil or heat exchange manifold. In this way, the energy used for mashing can also be harnessed to heat up the sparge water, making the whole process more efficient. RIMS and HERMS can be used together in order to expedite a very efficient brewing set up.

Decoction
An entirely different method of mashing, recommended for German beers and beers with larger grists (high gravity beers). This method derives from older days, when thermometers were not widely available to brewers. Brewers used their thumbs to test the temperature of the mash (Rule of Thumb).

The method involves ladling out a portion of the mash and boiling it, and then returning that portion to the mash tun to raise temperatures when needed. This method is said to enhance the flavor of the beer in many ways. There is a different malt flavor that comes from this boil, as certain sugars are caramelized and proteins in the mash are coagulated and therefore more easily filtered out during lautering. It is theorized that this pre-boil breaks down cell walls, thereby freeing additional enzymes for conversion, although such high heats are known to destroy the starch converting enzymes, for the most part.

Decoction mashes are usually started with a single infusion mash. After that, multiple decoctions can increase the temperature of the mash in stages, providing not only for starch conversion, but also for a protein rest, amylase rests, and acid rests. Most decoctions use a ratio of 1.5 quarts of water to one pound of grain. The difficulty in decoction is making sure that the decocted portion of the mash does not become scorched when boiling. Stirring frequently and consistently will help with this.

Step Mashing
A mashing method that uses multiple steps of temperature, or ranges of temperature, to facilitate the mashing process. It is a somewhat holistic approach, intending to slowly achieve a transformation of the sugars into their most yeast friendly formats. The theory is that by slower heating, the conversions will be able to heat and thoroughly work through to completion before the next step in the mash takes place. This method takes longer, and usually is formed out of five steps, or temperature ranges, but these ranges also correspond with pH ranges for the various Rests: Alpha amylase, beta amylase, ideal mash temperature, glucanase, and protein rest. This method of mashing is the most time consuming, and requires a close attention to the temperature range and the pH of the wort. Most grains used in homebrewing are well modified and usually do not require these additional rests for proper starch conversion.

Christian Lavender is a homebrewer in Austin, TX and founder of Kegerators.com and HomeBrewing.com.

Related Articles:
Build a Mash Tun - A keggle project covering a full keg conversion into a fully functional (keggle) brew kettle/ mashing vessel.
Different Brewing Styles - Quick summary of malt extract method, partial grain method and all grain method.
Home Brewing in the Stone Age - Beer is an ancient drink.