Nope.
I mean, technically there is a tiny tiny bit of sugar in flour, but why would you think "flour" for Brett?
What is the purpose? One thing I've read time and time and time and time and time and time again is that Brett doesn't need anything to eat. Theoretically, even if you added Brett to something of 1.000 gravity, it would still add Brett character over time. But, put simply, "flour" is NOT a good food source for Brett,