Method of making

(1) to acid decomposition glucose acid calcium, by ion exchange resin off calcium, will glucose acid liquid in 70 ℃ following vacuum concentrated to 80% around, into glucose acid-δ-within ester of Crystal species, in 40~45℃ in the continues to vacuum evaporation, dang has 1/2 of glucose acid within ester form precipitation Crystal Shi, stop evaporation, ion separation, with cold water washing, and dry, have finished.

(2) direct use of gluconic acid solution, vacuum concentration in 40~45℃ made further.