传统牛乳浓缩工艺通过加热蒸发水分实现浓缩,具有蛋白质受热变性、感官品质降低、生产效率低及无法去除乳糖等问题。引入超滤技术以脱脂牛乳为原料制备无乳糖牛乳蛋白浓缩物(milk protein concentrate,MPC)以弥补传统工艺的缺陷,并对分...传统牛乳浓缩工艺通过加热蒸发水分实现浓缩,具有蛋白质受热变性、感官品质降低、生产效率低及无法去除乳糖等问题。引入超滤技术以脱脂牛乳为原料制备无乳糖牛乳蛋白浓缩物(milk protein concentrate,MPC)以弥补传统工艺的缺陷,并对分离过程中的分离系统、洗滤模式及操作条件等工艺进行优化。最终采用分离精度为10 kDa的聚醚砜中空纤维超滤膜组件在自制膜分离系统中以40℃、0.1 MPa的操作条件下2倍浓缩、3次反洗补水洗滤制备了乳糖质量浓度为1.17 g/L、蛋白收率为94.0%、蛋白质量浓度为40.01 g/L、pH值为6.98、乳糖脱除率为96.5%的无乳糖MPC。超滤浓缩技术有效去除了乳糖,且工艺优化显著提高了生产效率与产品质量,制备出的无乳糖MPC可实现乳产品组分的优化。展开更多
The electrochemical behavior of rhein modified glassy carbon electrodes were studied. Three peaks in CV appeared in the potential rang of +0.4\-0.8 V\%（vs\%. Ag/AgCl） in 0.06 mol/L H\-2SO\-4. p\-1 and p\-3 are a cou...The electrochemical behavior of rhein modified glassy carbon electrodes were studied. Three peaks in CV appeared in the potential rang of +0.4\-0.8 V\%（vs\%. Ag/AgCl） in 0.06 mol/L H\-2SO\-4. p\-1 and p\-3 are a couples of oxidation\|reduction peak, the electrode process contains two electrons and two protons. The formal potential（\%E\%\+\{o\} ）is -0.202 V（\%vs\%. Ag/AgCl） at the scanning rate of 50 mV/s. The cathodic peak potential shifts linearly in the negative direction with increasing solution pH with a slope of 67 mV per pH unit. The rhein modified electrode shows an electrocatalytic activity for reduction of hemoglobin in 0.06 mol/L H\-2SO\-4 solution. The peak currents are proportional to the concentrations of the hemoglobin in the range of 6.0×10\+\{-8\}\1.3×10\+\{-6\} mol/L, the relative standard deviation is 3.5% for 6 successive determination of 1.0×10\+\{-7\} mol/L hemoglobin solution. The catalytic mechanism has been discussed.展开更多
文摘The electrochemical behavior of rhein modified glassy carbon electrodes were studied. Three peaks in CV appeared in the potential rang of +0.4\-0.8 V\%（vs\%. Ag/AgCl） in 0.06 mol/L H\-2SO\-4. p\-1 and p\-3 are a couples of oxidation\|reduction peak, the electrode process contains two electrons and two protons. The formal potential（\%E\%\+\{o\} ）is -0.202 V（\%vs\%. Ag/AgCl） at the scanning rate of 50 mV/s. The cathodic peak potential shifts linearly in the negative direction with increasing solution pH with a slope of 67 mV per pH unit. The rhein modified electrode shows an electrocatalytic activity for reduction of hemoglobin in 0.06 mol/L H\-2SO\-4 solution. The peak currents are proportional to the concentrations of the hemoglobin in the range of 6.0×10\+\{-8\}\1.3×10\+\{-6\} mol/L, the relative standard deviation is 3.5% for 6 successive determination of 1.0×10\+\{-7\} mol/L hemoglobin solution. The catalytic mechanism has been discussed.
