突变芳香基硫酸酯酶改性琼脂的工艺优化及其性能表征

目的:明确食鹿角菜交替假单胞菌突变芳香基硫酸酯酶K253Q改性琼脂的制备工艺，表征酶法改性琼脂的性能特征。方法:以硫酸根脱除率为评价指标，考察反应时间、加酶量、温度、pH对突变芳香基硫酸酯酶K253Q处理琼脂的影响，并对理化性质和结构进行表征。结果:以4 g琼脂为原料，确定最佳工艺条件为:反应时间6 h，加酶量80 U，反应温度50℃，初始pH7.0。另外，以100 g琼脂为原料进行放大实验，在最佳工艺条件下，硫酸根脱除率达到50.1%。在此条件下，K253Q处理后琼脂的凝胶强度、3，6-内醚半乳糖含量、白度和透明度均有显著提高，而灰分和粘度值显著降低（P<0.05）。扫描电镜分析显示，K253Q处理琼脂的微观结构表面突起之间连接更加紧密，表面更光滑。结论:K253Q处理琼脂后提高了琼脂的品质，琼脂硫酸根含量降低，凝胶强度、3，6-内醚半乳糖含量、白度和透明度提高，灰分降低。

Preparation and Characterization of Mutant Arylsulfatase-Modified Agar

Objective:To determine the preparation technology of mutant K253Q arylsulfatase(from Pseudoalteromonas carrageenovora)modified agar and to characterize its properties.Methods:Taking the sulfate removal rate as the evaluation index,the effects of reaction time,enzyme dosage,temperature and pH on the treatment of agar by mutant arylsulfatase K253Q were investigated,and the physical and chemical properties and structure were characterized.Results:4 g agar was used as raw material.The optimum conditions were as follows:reaction time 6 h,enzyme amount 80 U reaction temperature 50℃,initial pH7.0.In addition,100 g agar was used as the raw material for the scale-up experiment.Under the optimum conditions,the sulfate removal rate was up to 50.1%.Under these conditions,the gel strength,3,6 anhydrogalactose,whiteness and transparency of agar increased significantly after K253Q treatment,while ash and viscosity decreased significantly(P<0.05).SEM analysis showed that the surface of K253Q treated agar was more connected and the surface was smoother.Conclusion:Agar treatment with K253Q enhanced the quality of agar,decreased the content of agar sulfate,increased gel strength,3,6 anhydrogalactose,whiteness and transparency,and reduced ash content.