For caramel popcorn processed at very high heat (around 290–300°F): which colors will work?

High-heat applications like caramel popcorn are among the more challenging environments for natural colors. We've discussed red and green liquid options for this type of application, both of which have better heat tolerance than some other naturals, but the honest expectation is that heat at this level will mute the color to some degree in almost any natural pigment. The best approach is to validate the finished shade after your complete process — including the full heat cycle — rather than judging the color before cooking. If your process allows it, adding the color as late as possible before the final set can help preserve more vibrancy. Sampling and in-process testing are the most reliable way to determine what's achievable within your specific conditions.