Our homebrew set up hasn’t changed much in the three plus years we have been brewing beer at home. We have a 10-gallon brew kettle, a 10-gallon cooler mash tun, and another 5-gallon cooler we use as an HLT. This set up works for us and we produce some pretty good beer on it. However, with a mash tun and HLT that are coolers, we lack the ability to easily add heat and we found ourselves longing for a way to step mash.

Step mashing is a mash schedule in which the mash temperature is increased through a series of rests. Multi-step mashes used to be the standard for making beer, however, with the rise of well modified malts this technique has been left behind in favor of the easier and less time-consuming single temperature infusion mash. Although not necessary there are many styles that benefit from this more traditional way of brewing. Particularly, traditional German and Belgian styles fall into this category and we found ourselves set on brewing a Wiezenbock.

Luckily for me, this desire happened to coincide with Black Friday and I found a Sous Vide on the top of my guy’s wish list. And it occurred to me that it could be the best (cheapest?) way to solve our step mash problem without needing to buy or build a HERMS/RIMS setup.

Sous Vide

Sous Vide is a French technique that translates into “under vacuum”. It is a process of cooking food sealed in an airtight bag by submerging it into heated water that is kept at a constant temperature. A Sous Vide appliance is basically a wand that clips onto the side of a pot, or in our case mash tun cooler, with an electric heating element and a small propeller that circulates the water to maintain the temperature set by the user.

There are a few things to consider when choosing this type of an appliance. First, you want to make sure that the Sous Vide cooker you purchase matches the size of batch you are making. For example, we typically brew about 6 to 7 gallons and mash with about 4 gallons depending, of course, on the recipe. You want to choose a device that will have enough power to circulate the amount of water you are mashing with. If you choose a device without enough power, you will only heat a portion of the water to the step temperatures. I purchased the Anova Culinary Sous Vide Precision Cooker. It has 900 watts of power and worked well for our first attempt at Sous Vide Step Mashing.

Additionally, you will need a BIAB bag or some other way to separate the grain and water if you intend to use a Sous Vide. We use a BIAB bag every time to make the vorlauf and clean up a breeze, but this time it was used to keep a separation between the grain and the appliance. If grain is sucked into the appliance it can scorch the grain, clog the appliance, and I would imagine it'd be a mess to clean up and would likely decrease the life of the appliance.

sous vide cooker temps

Brew Day

On brew day we clipped the bracket of the sous vide onto the side of the mash tun. We then used binder clips to clip the bag to the rest of the mash tun. We heated about 5 gallons to 131F to mash in and then let it cool to 122F and sit for 15 mins for our protein rest. Our second step, the saccharification rest, required a rise in temperature to 148F. The Sous Vide preformed this beautifully and accomplished the 26-degree temperature rise in about 5 minutes. We stayed within a half of a degree of 148F for 60 minutes. This was despite a cool windy day with no lid on our mash tun. We then increased the temperature for mash out to 168F for another 10 minutes and then proceeded with our typical batch sparge.

Our typical brewhouse efficiency is 72%. This particular brew day we checked in with a brewhouse efficiency of 62%. I don’t know if that was due to the step mash or because this recipe was probably the heaviest wheat percentage we have ever brewed with. Over 50% of our grain bill was wheat.  When we brew this again, we will probably do a straight Brew in the Bag method with no batch sparge. But I have also read an article in Brew Your Own in which they split the grain bill and water between 4 sealed bags and then immersed them in water with the sous vide. After mashing they filtered the wort from the grain through a BiaB bag and proceeded with a normal brew day. They claimed a 95% efficiency mashing this way with a sous vide. It’s an experiment I will be attempting very soon so stay tuned for a follow up.

Overall, I am happy with the way the sous vide preformed for our step mash. It was able to hit the steps quickly and maintain temperature throughout the mash process. It will be a tool I will use again regularly.

--Sandra DiPretore
Cicerone Certified Beer Server, Homebrewer, and Tireless Recipe Researcher