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Yes you can find hightemp food grade silicone I picked some up localy for my smoke shack. I will have to check and see the brand name but they have it online.
The regular kitchen and bath caulk I use has a temp rating of around 600 deg. IIRC. If I exceed those temps I've got bigger concerns than my caulking. I use Dap or GE brand.
I would try to find one that specifically says "food grade". The standard bath/kitchen stuff might have some nasty off gasing as it heats. Probably not enough to harm you, but why take the chance.
That is where I found my high temp food grade stuff. I called every hardware store and they had no clue what I was talking about. I finally called a restaurant supply place and they didn't have it but they told me where they buy it in town. Some place I had never hear of before. They should either have some or know where to get some.