A process for the production of a fermentation starting material from cane molasses which comprises: inverting most of the sugar contained in cane molasses either enzymatically with invertase or with a mineral acid, passing the cane molasses containing invert sugar through a column containing a cation exchange resin, eluting invert sugar from the resin with water (pH 5-8), and obtaining an eluate fraction containing the invert sugar to be used as a carbon source for the production of L-glutamic acid by a fermentation technique.