I can speculate: since hydrogen peroxide is an oxidant, and many lipids in grains are prone to oxidation/rancidity due to unsaturated sites, it seems reasonable to conclude that lipid oxidation will occur when soaking grains in hydrogen peroxide solutions. (There are other components that are probably prone to oxidation as well, including dyes/chromophores, antioxidants, and so-on.) Whether that constitutes a "negative impact" depends on what your definition of a negative impact is, and what your property of interest is.
If you want a more informed answer, I suggest searching the primary literature. Which you probably will want to do anyway, if you are doing research in this area.