Study On The Preparation And Decoloration Of High Purify γ-Aminobutyric Acid

Gama-aminobutyric acid (GABA) produced by Lactobacillus SK005 in a pilot scale 3000 L bioreactor and decolorizing technique of GABA were studied in this paper. The purpose is to find the optimum condition to produce GABA with high purity in large scale. The determination of GABA by paper chromatogram extraction spectrometry was also studied.Determination of the GABA in ferment broth by HPLC (High Performance Liquid Chromatography) and the paper chromatography extraction spectrometry method showed that the two methods made slight difference, suggesting spectrometric method can replace HPLC method in GABA assay. Applications of the spectrometric method in GABA separation and purification proved that the method was rapid, reliable and effective.Investigation on the production of GABA by Lactobacillus SK005 in a pilot scale 3000 L bioreactor showed that the method was feasible and reliable. The total recovery ratio was 79.748% and the final purity of GABA was 46.17% around the whole technique. The colorant content of enriched GABA was regarded as key indexes of purity. Caramel is the main species in colorants of enriched GABA. The colorant content was not sensitive to the solar and pH, however it was sensitive to the difference in temperature.The thermodynamics of adsorption and decoloration for enriched GABA by using NKA-9 adsorbent resin were studied. The results showed that the adsorption data of NKA-9 adsorbent resin fitted with Freundlich models. The changes of adsorption enthalpy value (?H) indicated the endothermic reaction was spontaneous and nature of the process. The adsorption ability was improved with increasing temperature, but the suitable temperature was 333 K for the equilibrium of adsorption efficiency between 333 K and 353 K. The optimum operation conditions were: pH 5.0, the adsorption velocity of flow 0.30 m/h, the operation temperature 333K and the inlet concentration A440 0.941. Ethanol in alkaline condition was the efficient regeneration.The adsorption and decoloration of macroporous anion exchange resins were studied. The six anion adsorbents were correlated with Freundlich models of isotherm equation and the best adsorbent was selected. The kinetic process of adsorption and decoloration by D201 was analyzed. The results showed that both the external diffusion and the particle diffusion were the rate-controlling step. The optimum operation conditions were: pH 10.0, the adsorption velocity of flow 0.30 m/h, the operation temperature 313K and the inlet concentration A440 0.941.The combine decoloration technique was studied based on the adsorbent decoloration and ion-exchange decoloration. The enriched GABA was decolorized by the NKA-9 adsorbent firstly and then decolorized by the D201 anion exchange resin. It was proved that the combine decoloration technique has good properties of reducing protein content and decolorizing effect. The final purity of GABA was 90.8%.