All-Grain Brew Day Walkthrough (V: Mash Out and Recirculation)


Mashing out lowers the viscosity of your wort and makes it easier to lauter

This is the fifth installment in the All-Grain Brew Day Walkthough, which started with a post on strike water preparation


When the mash is over, there is a sudden flurry of activity by the brewer. The brewer should mash out by heating the mash directly, or infusing it with boiling water, to raise the temperature to 170 °F (77 °C). If a brewer has mashed in his or her kettle, he or she may heat the mash to a couple degrees above this, then scoop the contents over to their lauter tun (where it will hopefully settle in around 170 °F (77 °C). In addition, if the brewer expects — based on past experience — that the grain bed temperature will decrease during recirculation, he may heat the mash to a few degrees over 170 °F (77 °C). With the relatively low pH of an undiluted mash, excess tannin extraction is not a problem, even when the grain bed exceeds 170 °F (77 °C).

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All-Grain Brew Day Walkthrough (IV: The Mash)

This is the fourth installment in the All-Grain Brew Day Walkthough, which started with a post on strike water preparation



The mash — hot brewing liquor mixed with crushed malt.

This walkthrough is going to focus mostly on the practical. However, at this point, let’s stop and think about what’s going on in the mash. While the mash is progressing, the homebrewer typically does fairly little. He might stir the mash, or his rig may circulate the wort through the grain bed for him, but it’s mostly downtime for the brewer. At the end of the article, I’ll focus on the things you can be doing during the mash, but first, let’s examine what’s happening in the mash tun.

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Two Mash Out Options


At the beginning of wort collection, it doesn’t matter if your grain bed temperature climbs above 170 °F (77 °C); tannin extraction is largely suppressed at mash pH.

At the end of your mash, you have the option of mashing out — raising the temperature of the mash to 168–170 °F (76–77 °C) — before recirculating and collecting your wort. The best reason to mash out is to make lautering easier. The hotter the mash, the lower the viscosity of the entrained wort and the easier it is to drain it away from the grain solids in your lauter tun. However, the difference in wort viscosity between wort at typical mash temperatures (148–162 °F/64–72 °C) and wort at 168–170 °F (76–77 °C) is not that great, and so many homebrewers simply skip this step without any noticeable negative effects. (For brewers who mash in a converted picnic cooler, often the volume of boiling water necessary to raise the temperature would cause their mash/lauter tun to overflow.)

I can heat my mash tun, so I usually mash out with the idea that at least it can’t hurt. (Plus, it requires me to stir the mash and that might help out my extract efficiency a little bit.) I like to tinker with my brewday procedures, and in this article I’d like to present two alternative ways to mash out besides the usual heat-and-stir and add-boiling-water methods. I’ve used the first option a number of times and it works fine. I accidentally did the second option a grand total of once — and it wasn’t until after the fact that I realized it might be a good idea. So, treat the second option as something to consider, not something that has been thoroughly tested.

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