Electro‐membrane reactor for the conversion of lysine monohydrochloride to lysine by in situ ion substitution and separation

BACKGROUND: Commercially lysine (Lys) is produced as lysine monohydrochloride (LysCl). The presence of chloride ion (Cl⁻) in Lys makes it unfit for use in pharmaceutical and livestock feed industries. Various separation methods are required to achieve Lys from fermentation broths. This paper describes an electro‐membrane reactor with three compartments (EMR‐3) for the conversion of LysCl into Lys by in situ ion substitution and separation. RESULTS: The conversion of LysCl into Lys in EMR‐3 is achieved by in situ ion substitution and separation using organic‐inorganic hybrid anion‐exchange membrane (AEM). It is found that the rate of Lys formation is dependent on applied current densities and LysCl concentration. The 96.2% Lys is recovered and low energy (2.07 kWh kg⁻¹) is consumed during the conversion of 0.10 mol L⁻¹ LysCl in EMR‐3 at 10 mA cm⁻². Moreover, high current efficiency (93.02%) is achieved under the similar experimental conditions. CONCLUSIONS: On the basis of process parameters (high Lys recovery and CE and low W), it is concluded that the developed electro‐membrane reactor can be efficiently applied for the conversion of LysCl into Lys in an economically viable manner. © 2012 Society of Chemical Industry  

碱性氨基酸修饰乳清蛋白基质凝胶功能性

将L-精氨酸（L-Arg）、L-赖氨酸（L-Lys）和L-组氨酸（L-His）分别加入到质量浓度为120 g/L的乳清蛋白溶液中，使每种氨基酸的最终质量浓度均分别为1 g/L、3 g/L和5 g/L，均质后再经90 ℃加热30 min制备热诱导凝胶，并探讨碱性氨基酸对凝胶功能的改造。通过物化、全质构、吸水性和凝胶电泳等分析手段，表征溶液的pH及其所成凝胶的形貌、质构、水化性质及凝胶内的蛋白浸出组分。结果表明，L-Arg、L-Lys及L-His均能明显提高蛋白成胶溶液的pH，蛋白都能形成颜色、形貌及“站立性”无明显差别的热诱导凝胶；L-Arg、L-Lys显著提高凝胶弹性、黏聚性、咀嚼性及回复性，降低凝胶硬度和胶黏性，而L-His除降低胶黏性外，对凝胶其它质构特性无显著影响。此外，它们对凝胶持水性提升幅度不大，但能够显著提高凝胶溶胀性，并有效抑制凝胶网络内蛋白浸出，促进蛋白凝胶网络结构的完整化。