Study On The Separation And Purification Process Of The Functional Food Additive-Glutathione

Glutathione, bio-synthesized from L-glutamic acid, L-cysteine and glycine in two consecutive steps byγ-glutamyl-cysteine synthase (GSH I, EC 6.3.2.2) and glutathione synthase (GSH II, EC 6.3.2.3), is one of the major non-protein thiol compounds. GSH (the reduced form of glutathione) is widely distributed in nature and plays many important physiological roles in living cells, such as enhancing the immunity of the body promptly and maintaining the normal redox environment of cells as an antioxidant. Since GSH is widely used in many fields, i.e. clinical medicine, food industry, athletic sports and biological research, the demand of GSH has been expanding. In this paper, the separation and purification process of glutathione from Candida utilis WSH 02-08 were investigated in detail. The main results were described as follows:1. It was found that the stability of GSH was determined by pH and temperature in the extracting solution. In addition, a high GSH stability was observed when pH value at the range of 1 to 2 and at room-temperature for two days. Furthermore, only a little of GSH was degraded when GSH extract was treated by 100℃for 20 minutes. Those results indicted that, an optimization pH and temperature is required for GSH separation and purification.2. An optimal operation parameters for removing protein from Candida utilis WSH 02-08 extraction by ultrafiltraion were determined. At the same time, in order to further increase the recovery rate of GSH, the advantages and disadvantages of dormancy dilution (DD) and continuous dilution (CD) were compared. Base on those results, an integrated processing of DD and ultrafiltraion was determined and as the most effective method to separate and purify. Furthermore, the cleaning process of ultrafiltration membrane was also determined in this paper.3. The affects of ultrafiltraion on the exchange action of GSH on cation exchange resin(001×7)were studied. The optimal parameters of adsorption and elution were determined through the study of conditions affecting ion exchanging and adsorption of fixed bed .The results was fellow: the recovery rate of GSH 80.2%, the removal rate of protein 60%, the concentration ratio of GSH 2.5:1 (at most 8.3:1), the purification rate 3.9. With those optimal conditions, an efficient GSH separation was achieved.4. Based on those results, an industrialized process for GSH extraction was developed. A end-product which contain 11.3% GSH was obtained, after Candida utilis WSH 02-08 was treated by extracted, ion exchanged, concentrated and dried.