continuously separating L-ascorbic acid from unreacted 2-keto-L-gulonic acid compound in the post-reaction solution to form an L-ascorbic acid solution and a solution of unreacted 2-keto-L-gulonic acid compound wherein the L-ascorbic acid solution has a ratio of L-ascorbic acid to 2-keto-L-gulonic acid that has been increased relative to the post-reaction of step (b) and the solution of unreacted 2-keto-L-gulonic acid has a ratio of 2-keto-L-gulonic acid to L-ascorbic acid that has been increased relative to the post-reaction of step (b); and