OP here -- that is interesting about dyes/diet. Thank you -- doesn't hurt to look into it.
Re: what we do -- at home, we ignore the behavior and don't reward tantrums/give into demands. Child usually cools quickly. Ignoring is not as easy in the classroom, when Child is flipping chairs or physically swiping at students. This is what I fear most. Can they kick you out of kindergarten?! Kidding. Kind of.
There's no rhyme or reason or pattern to outbursts (hunger, tired, etc.). It's generally when Child has an idea of how things will go, and reality doesn't match up.