I've had a beard, or some sort of substantial facial hair (by substantial, I mean something more than just a 1/4" closely trimmed scruff, and usually a goatee that was a few inches long, but I'm currently, for the past 3 years, wearing a 2-3 inch long full beard.)

I wear a beard guard every day (they have a bag of them at work for visitors, also), and I bought my own bag of them on Ebay (I think they were only like $5) and I keep a few in my work bag.

Be up front with the interviewer about the facial hair. Know that a lot of larger places may actually have facial hair listed in their dress code, or it may be forbidden as a condition of employment. Tell them that you would like to keep the beard, and have absolutely no problem wearing a beard guard to comply with health department regulations. It might even give you a bit of an edge if you offer to provide your own beard guards so they don't have to worry about it. (and if you really want to keep the beard, you can consider the cost of the beard guards as a "beard tax")

If you expect to get through an interview to the point where they're interested, and offer to show you the kitchen, it might also help if you bring a beard guard with you to throw on before you walk into the kitchen. At the very least, it would show a potential employer that you take it seriously, even if you're just walking through the kitchen, that you are following the health department guidelines of covering the beard. I did this for my last interview: brought my own beard guard, and put it on for the kitchen tour. The chef was impressed that I was prepared for that.

You don't need to bring it up at the beginning of the interview, because if it's a huge deal for the interviewer, they're going to mention it at some point. Personally, if it doesn't get mentioned during the interview, I would make sure to ask at the very end, at least. When they ask you if you have any questions for them, just say something like "As long as I wear a beard guard, and follow the health department rules about the facial hair, my beard won't be a problem, will it?"