Yes they can. The kind of bleach that should be used is industrial strength, If you are thinking of doing this yourself use extreme caution! Its a job best done by a pro. However the "yellow problem" can also be stained ie white washed rather then bleached as well. All depends on the look you wish to acheive.

Thanks for your prompt answer. Industrial bleach sounds like something I don't want to use! What exactly is whitewashing? What products are used?

do the cabinets have any finish on them stains or clears

Morning:) Next time you are at a paint store or box store look at a can of Minwax pickeled oak. That can be considered a white wash. One thing to consider, the pine is yellow. The white stains tend to lean blue in tone. What happens when you mix blue and yellow? One gets green. Always test before.

Thanks. That is definitely something to consider. I will be sur to test first.

The cabinets have been stained and look like they may have polyurethane on top of the stain.

Don't use bleach, it is too dangerous and corrosive and also unnecessary. Look for paint recipes for pickling or whitewashing. You could then come back in with a brown stain or glaze. Definitely do some serious tests and trial runs on knotty pine scrap first. If successful, take off some doors and do the insides and review the look before you commit all your cabs.

Thank you for your advice. I will definitely not use bleach!