The Russian and American space agencies both had a look at this (1960-70s I think). Short answer is: I hope they like like glycerol and starch!
This is the closest I know of that we have come to producing synthetic food from water and electricity (apart from 'electro single cell protein') and even then you would slowly be dying from vitamin deficiencies.
FYI I would hope that crew morale is good or future technology has improved the flavour as having this all day everyday would be interesting!