What is the significance of Pellicori's discovery that some blood was brown?
By untwisting some of the threads of the Shroud, S. F. Pellicori determined that the blood on the inside of the threads was brown while on the outside it was red. This lends credence to the hypothesis that the blood remained red due to a hemolytic agent such as Saponaria officinalis (Soapwort).
Small amounts of dissolved soap as well as starch fractions (starch was found on the fibers in a layer that appears to be a residue) would have ended up only on the outer surface of the threads due to evaporation concentration.
Soapy residues and small amounts of starch remain in a water soaked piece of linen. As the cloth dries, moisture wicks its way to the surface to evaporate into the air. As the water makes its way to the surface it carries with it dissolved starch fractions and saccharides. As the water evaporates into the air these chemicals are deposited as a super thin coating on the crown fibers, the very outermost fibers of the thread. Chemists say this superficial residue of reactive saccharides is on the surface of the cloth.