I've had problems with low efficiency when I have a large percentage of wheat in my BIAB batches. I am planning a Hefeweizen recipe that will be 60% white wheat malt and I want to get it right this time.

Does anyone have experience with doing a protein rest in BIAB?
Does anyone think this might improve my efficiency issue?

My biggest concern is rising up to the full mash temp after the protein rest without over shooting. It's difficult for me to adjust the temp in a 10 gallon batch once the grain is in the kettle.

  • What are your efficiency figures? BIAB without sparge will always have a lower efficiency? – chthon Aug 17 '17 at 8:47

I do BIAB, and I don't think protein rest has much with extraction efficiency. Mashout temperature has, however: if wort has lower viscosity due to higher temperature, it will better flow from the grist. Another thing I do is "micro-sparge" with 1-2 liters of water over the grain bag (in my case it's a basket, actually) on top of the kettle.

When it comes to raising temperature, you have two options: 1. heat the kettle (which you seem to do), but then you need to constantly stir the mash; 2. hot water addition, which can be calculated (tons of calculators online for it) and you can avoid overshooting -- BIAB is thin mash, so starting with partial amount of water should not be a problem. Actually, I use the option 1 with re-circulation and electronic temperature controller, but you may want to check option 2.

Lastly, every homebrew book author says that modern malts don't need protein rest. Hefe, however, may profit from ferrulic rest (42-43C).

The problem is probably in the overshoot. If you overshoot the temperature of the beta amylase you are not gonna get a good (planned/calculated) efficiency. This will not be fixed by a protein rest. We ran into the same problem when we did BIAB. What it really means is you need to get to know your setup.

Make sure you stir well while heating, and take regular temperature measurements. When you are close to your target temperature turn off the heat, stir for a while and measure. The water will heat faster than the grains so it will need some time to even out, also, the bottom of your pan will be hot and still pass some heat to the wort right after you turn of the fire.

We used to make sure we always measured the water temperature during the heating, and when that hit our target temperature we would turn off the heat and keep stirring. Measure the temperature again after stirring well and see if you need to heat some more. At some point we pretty much knew at what water temperature to turn the heat off.

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