The Gudger & Ferguson Step Mashing Method (a more affordable HERMS system)

Most all-grain brewers employ a single temperature mashing method.  This mash is a single temperature rest between 148F and 158F, depending on the brewer's preference of fermentability and mouthfeel.  This is also known as the Infusion Mash.  There are three other common mashing methods which incorporate the use of multiple increasing temperature rests.


Both Decoction Mashing and Step Mashing below often utilize the following temperature rests:
        97F - Acid Rest
        120-134F - Protein Rest
        148-158F - Normal Saccarification Rest (Infusion Mash Temperature)
        170 - Mash-out Temperature

1)  Decoction Mashing is a process by which a specific amount of the mash is removed, boiled, then returned to the whole mash in order to raise the temperature of the whole mash to a predetermined amount.  Below is a sample Decoction Mashing schedule:

2)  Step Mashing -- RIMS (Recirculating Infusion Mash System) is similar, but involves carefully heating the mash to these temperatures with direct heat.  This means either a brew kettle over a heat source is used as a mash tun or it is directly exposed to an electric immersion heater.


3)  Step Mashing -- HERMS (Heat Exchange Recirculating Mash System) involves warming the mash through a medium such as water by way of a copper, or other, coil.  This takes the direct heat away from the mash itself.


Decoction, RIMS and HERMS have drawbacks :

--Decoction Mashing involves pulling grains out of the main mash, which can be awkward and messy.  It also means boiling some grain in the decocted portion, which can impart some harsher flavors from the husk of the grain.  Boiling also denatures enzymes necessary for mashing.

--RIMS applies direct heat to the mash which can result in off-flavors and requires constant stirring.  A brew kettle which is employed as a mash tun also loses heat, particularly with smaller batch sizes.  My version of HERMS solves all of these problems.

--My system is a HERMS, but saves a lot on the cost of a typical setup.  It's also easy to try out with usual brewing equipment you may already have without spending money.

I have recently tested a new method which is similar to Decoction and Step Mashing, but without any of the detrimental effects of either one.




The Gudger & Ferguson Step Mashing Method (AKA, the simplest form of the 3) HERM System)

 My method warms the mash efficiently to each increasing temperature by circulating the mash from the mash tun, through a copper coil placed in a pot with heated water, then back into the top of the mash tun.  This is normal all-grain circulation, but it includes the warming apparatus.  I have created this warming apparatus by filling the brew kettle with water which is warmed to each progressive temperature with a burner and running the mash through a copper coil which is placed into the kettle.

This process worked beautifully the first time and achieved each incremental temperature quickly and efficiently.

I envision a permanent version of this which could be heated with an immersion chiller and regulated with a thermostat control (I have the Johnson Controls A 419).  I searched the US Patent Office database, however, just to discover this exact device is already patented and utilized by a construction company in Ashland, TN for another application.  You can still utilize the principal, though.

I hope this gives you something to think about and if you have tried this already or have feedback on the design, please leave me a message.  Enjoy!