Whirlpools and Recirculation

27 Mar

IMG_20160102_123502I’ve been pondering a couple of brewing techniques over the last few days, one based on my attempt to use it in the last few brews, the other from my research of mild ales, the style of the next beer I will be making.

I got my new electric brew kettle in part because I thought it would make creating a whirlpool at the end of the boil easier. With the electric coil and the hop filter, stirring with a brew spoon hasn’t been terribly effective. Everything I’ve read suggests that the longer you can keep the whirlpool going, the better its effect will be in terms of collecting in the center of the kettle the hop debris and other material you don’t want to transfer into the fermenter. Whether you use a racking cane or have a port or dip tube like my kettle, that makes it easier to pull more clear wort out at the end.

I did a bit more researching, thinking maybe a drill attachment might work. There is only one such gadget marketed for the purpose and it isn’t guaranteed to fit all drill chucks. In addition there is a risk with using a drill attachment of something called hot side aeration. While apparently not a huge risk at home brew scale, introducing too much oxygen while the wort is hot can encourage the creation of compounds responsible for certain off flavors. My key concern with my mild ale is preserving all of its full range of desirable flavors, some of which may be quite subtle, without introducing even an iota of something undesirable. Unlike other styles I have made, there won’t be anything strong enough to mask even trace levels of badness.

I found an AHA article that explains how to create a whirlpool both by stirring and by using a pump. Since this is a home brewing article, the pump in question is going to be pretty much exactly like the two that I have. Pumping is how commercial brewers perform this same technique. The idea is to place the outflow just a few inches below the surface of the wort. I only recently got the knack of priming my pumps well so I know that they can generate a good deal of pressure. I will do a dry run with cleaning solution both because my pumps and plate chiller could use the cleaning and to be sure this will work as planned on the day.

The more I think about the approach though the more I like it. For starters, I am getting more value out of my investment in pumps, especially since I picked up a second to address earlier problems with my rig. I can use my chilling set up exactly as I have before just placing the outflow in the kettle for a few minutes before moving it to the fermenter. Since I will be creating my whirlpool with wort I am also chilling, it will help get the whole batch to a lower temperature, faster.

On the last brew day, running straight into the fermenter resulted in a slightly higher pitching temperature than what would have been ideal. For a full flavor or higher alcohol beer, pitching a little warmer is not a big concern but again with a much more delicate, lower alcohol beer like my next one, I think I will be giving myself more of a margin for success.

I have been thinking about my sparge technique as a result of David Sutula’s recommendations in his book, “Mild Ale“. He warns not to pull off from the mash tun too quickly, to take care not to drill into the mash bed when doing the vorlhauf or sparging, and to avoid oversparging. For home brewers, he suggests using a saucer on top of the grain bed as a diffuser. My sparge rig has a diffuser at the end of the sparge arm. Up until now, I have only pushed hot sparge water through that arm, doing the vorlhauf by pulling into a steel pitcher that I do my best to diffuse back over the grain bed.

I have seen mentions of re-circulating during or at the end of the mash. I have some acquaintances who mash this way. It requires a pump, a bit of gear I am increasingly comfortable using. If I first connect the inflow of my usual sparge set up to the outlet of my mash tun before switching to my hot liquor tank, I can recirculate at the end of the mash taking full advantage of the sparge arm to properly diffuse what will replace my vorlhauf. My mash calculator recommends a pretty high volume for pushing that first running back through the grain bed. How much easier it will be to do that with a pump rather than fiddling with a ball valve, a pitcher and using even an inverted saucer to diffuse.

I am not sure why I resisted re-circulating my mash for so long. When I had only one pump, I only used it for water and did so before the boil where sanitation was not as critical. Now that I am pumping wort through my plate chiller, I think I have gotten over the psychological barrier of somehow harming the beer by pushing it through a pump. Both of my pumps are equipped with ball valves so for mash re-circulation I can dial in the flow to avoid pulling the wort through the grain bed too quickly.

I will post updates both after the dry run in a few weeks for the whirlpool and after my next brew day about the mash re-circulation. I am pretty excited to give both of these techniques a try and hopefully to integrate them into my constantly evolving, and hopefully improving, home brewing process.

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