Difference between revisions of "Mashing procedures"

This article tries to explain the various mashing procedures that are of interest to the home brewer. Mashing procedures are basically the application of the Theory of Mashing by mixing the grain with water (mash) and resting this mash at a single or multiple temperatures to activate enzymatic activity which converts the grain solids into wort soluble compounds.

Which mash schedule to choose

This question comes up quite frequently in the form of "What benefit do I get from using a more complicated mash schedule than single temperature infusion?".

Mashing needs to be seen as an extension of the malting process and what wasn't done during the malting of the grain, needs to be done during mashing. And the more modified a malt is, the less mashing steps are necessary to produce a wort suitable for brewing a quality beer. Even worse, by selecting a more intense mashing schedule for a highly modified malt certain steps, like protein conversion, can be overdone and lead to a less optimal wort composition.

Here is a list of some malts showing mashing schedules that work well for them:

• American or British 2-row (Pale malts): single infusion mash
• Durst TurboPils: single infusion mash
• Durst Pilsner: single infusion or 2 step infusion
• Briess Pilsen: 2 step infusion / decoction mash
• Weyermann Pilsner: 2 step infusion
• home malted malt: multi step infusion / deoction mash

Single temperature infusion mash

The single infusion mash uses a single temperature rest at which the beta and alpha amylase enzymes are active to convert the malt starches into wort sugars. The higher the mash temperature is, the lower the limit of attenuation of the resulting wort will be. This is the most common mash schedule among home brewers and craft brewers because it is well suited for American and British 2-row malts which are generally highly modified and don't benefit from a lower temperature rests. It is also well suited for the use of unheated mash tuns (e.g. coolers) which are the preferred mash vessel among most home brewers. The rest temperatures are commonly between 149 *F (65 *C) and 165 *F (69 *C). Many brewers like to use 154 *F (67.5*C) as their preferred mash temp as it gives a nice balance of body and fermentability that works well for Britsh and American style ales.

In order to do a single infusion mash, the strike water (water used for the mash) is heated to a certain temperature such that when the grains are mixed in, the resulting temperature is the desired rest temperature. The temperature of the strike water can be calculated with the following formula [Palmer, 2006]:

Strike Water Temperature Tw = (.2/R)(T2 - T1) + T2

• R = Ratio of water to grain in quarts per pound
• T1 = the temperature of the grains in Farenheit (or Celsius)
• T2 = the target temperature of the mash in Farenheit (or Celsius)

Note: Plamer writes that R can be expressed as quarts per pound or liters per kilogram. This is not correct since 1 l/kg is aproximately 0.5 qt/lb. This needs to be accounted for when using metric units in the above formula. The temperature however can be used as Farenheit or Celsius as long as all temperature values use the same unit or measure.

Hitting the mash temperature is for many brewers their biggest problem when doing a single infusion mash. This can oftentimes lead to frustration. The reason for that is, that the above formula doesn't account for heat loss to the mash tun. It basically assumes that the mash tun has a termal capacity of 0. To get around this one can preheat the mash tun with some boiling water or adjust the strike water temperature based on the results in previos mashes. If the latter is used the brewer should keep the mash tun and grain temperature constant between the different mashes.

Another option of precisely hitting the mash temperature is to keep hot and cold water at hand and infuse about 80% of the strike water into the mash. The stir well to even out the mash temperature and measure the mash temperature. Now use hot and cold water infusions to get the mash to the desired mash temperature. This works well for thinner mashes and round mash tuns as the mash is easier to stir in them which is necessary to get a precise mash temp reading between the infusions.

With todays highly modified and thus enzymatic strong malts, the mash is generally converted after 15-30 min based on the rest temperature. Lower temperatures mashes convert slower than higher temp mashes of the same grist (see The Theory of Mashing for further details)