You don't need nor want to use a protein rest with fully (highly) modified grain.
That idea was born in 1977 by a grade school teacher attempting to make a name in brewing. The idea was put to rest years ago by Gambrinus Malting. The teacher disappeared into obscurity and never wrote anything again about brewing, after Gambrinus tests proved him wrong. Somehow, the idea stuck around. Protein rest length time is based on the SNR or the Kolbach of the malt. Malt above SNR 40, Kolbach 42, shouldn't have a protein rest. The malt is over modified. If an protein rest was employed, the beer would be very stable, but insipid. The rest can be over done when using high modified malt. Protein rest produces albuminus protein, responsible for foam and body. High modified malt is higher in protein than under modified. Wheat is high in protein, around 13% and has a high viscosity number. A beta glucan rest is a good thing to do to reduce viscosity in wheat or in base malt with viscosity over 1.3. The problem is, beta glucanase active around 105F is kilned out of American malt. A rest in the 122 to 130F range would allow proteolytic enzymes, that are not kilned out, to break down beta glucan to glucose and to break up long chain protein, useless for foam and body, but good for haze and lowering stability and shelf life. Going from boiler to belly in 4-6 weeks, none of that really matters. A data sheet on the malt being used comes in handy, as there are some numbers on it that will help a brewer to determine a process.
In Vol. 72, Journal of the IOB, 9 Apr 13. There's a paragraph about under modified malt as being better for foam retention and body.
Weyermann recommends a protein rest with a lot of their malt. Malt is kilned according to beer requirements. Cheap malt goes from the field to sack in a week. It takes over a week of malting and a week of kilning to produce good malt.
