Del, there is no finish that I know of, that will or can stop wood from loosing it color/changing in appearance. You'll find that over time no matter what you use, the wood will eventually change color. You will get one of two effects, it will either darken in color or it will lose most of its color. Generally, if I want a piece of wood to remain a certain color, I will use a tint or dye close to the original color of the wood. Then to finish the project, I'll use an automotive clear coat finish. This clear coat finish doesn't yellow, and you can get a beautiful finish from using it. However, it won't stop the wood from discoloring, that's what I use the dye for.
Len