Huh. Never heard of that.
On long unsupported rides I usually stop at a convenient store or Subway for an egg salad or tuna salad sandwich, but on supported rides where there's often no access to food other than the food stops, and they NEVER give you enough protein, I've carried pre-measured Ziploc bags of Perpetuem and mixed them with water as needed. Doesn't take too much room in a jersey pocket.
I try to avoid soy though - lately I've been making my own with one part Garden of Life Raw Protein Powder to two parts HEED. Got me through the marathon last weekend.
