I just got a hold of some organic raw spelt that I would like to use in a wit instead of flaked wheat.
- Do I need to gelatinize the spelt?
- How do I do that?
- Should the grain be milled at some point?
- How much of the grain bill can be unmalted wheat?
Assuming spelt has the same properties as wheat, there's no need to gelatinize the spelt as a separate step. The gelatinization temperature of wheat is low enough that it will occur at normal mashing temperatures.
You should mill the wheat in the normal way. If you're using a two-row mill like the Barley Crusher, you could set the gap slightly smaller than what you use for malted barley. Wheat kernels are smaller than barley, so a smaller gap will ensure a good crush.
How much you can use depends on the makeup of the remainder of the grist. You want to make sure that the diastatic (enzyme) power of the mash is sufficient to convert the starches in a reasonable amount of time. Diastatic power is measured in degrees Lintner. For the mash to be self-converting, the overall diastatic power should be at least 35 oL. Raw wheat provides no enzymes, so all the diastatic power of your mash will be coming from the other components of the grist. American 2-row malt is generally around 140 oL, so a 50/50 mix of unmalted wheat and 2-row would proved 70 oL of diastatic power -- more than enough to convert.