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Dear Manuella,
I have recently done some work on tortillas and tortilla dough structure. 
Staining was done by adding Safranin O ( I believe it was below 0.05% w/w)
before kneading the dough and eventually baking the tortillas. I have 
never seen pink tortillas before - this was fun.
 The gluten network stained very nicely (excitation with 488 nm laser, 
emission in green). The dough or a hand section through the baked tortilla 
was mounted in immersion oil on a slide (I did not want to use water as a 
mountant since this would cause swelling) and imaged using a 20x oil 
immersion objective. Because the dough is quite dense and the starch 
scatters light a lot, I could only get good images first ~20-30 microns 
into the tissue. This was still better than with either the dry or water 
immersion objectives. Using a different dye excitable with a longer 
wavelength laser would help, but this was good enough.   

Stan
 
Dr. Stanislav Vitha   
Microscopy and Imaging Center
Texas A&M University
BSBW 119
College Station, TX 77843-2257