Possible Clues:

• Gluey protein substance in flour
• Dough component
• Grain component
• Small measure behind oversupply to bakery standard
• Excess marks off fellows that some find hard to digest
• Protein present in cereal grains
• Part of wheat surplus went without packaging
• Ungrateful Frau dropped something that affects one's dough
• "___ free!" (health-food label)
• Protein left after starch is removed from cereal grains