不同预处理方式对柠檬果汁超滤澄清效果和膜污染情况的影响

利用超声辅助果胶酶法和超滤技术相结合对柠檬果汁进行澄清。以柠檬汁的透光率、果胶含量为指标,讨论不同预处理方式对柠檬果汁超滤澄清效果和膜污染情况的影响。结果表明,采用切割分子量为50 kDa的聚丙烯腈(PAN)超滤膜澄清果汁,不同预处理方式对超滤膜的稳定通量大小的影响规律是酶+超声处理>酶处理>未经酶+超声处理,其稳定通量分别为30、33.5和13 L·m-2·h-1左右。较优的操作压力可确定为0.1 MPa,此时柠檬汁的果胶含量为0.5%,透光率约99.6%,处理效果较好。超声辅助果胶酶法澄清果汁,有利于提高果汁的透光率,并且在后续膜处理过程中,对于提高超滤膜的通量和缓解膜污染都有显著的效果。

The Effect of Different Pre-treatment Methods on Ultrafiltration Clarification and Membrane Fouling of Lemon Juice

The clarification of lemon juice was carried out by the combination of ultrasonic-assisted pectinase and ultrafiltration technology. The degree of clarification and pectin content of lemon juice were used as evaluation indexes to discuss the effect of different pretreatment methods on the clarification effect and membrane fouling. The results showed that when a polyacrylonitrile(PAN)ultrafiltration membrane with molecular weight cut off(MWCO)50 kDa was adopt to clarify lemon juice,the influence of different pretreatment methods on the stable ultrafiltration flux was that enzyme plus ultrasonic treatment>enzyme treatment>without enzyme and ultrasonic treatment,the corresponding flux was about 30,33.5 and 13 L·m^-2·h^-1. The optimal operating pressure was determined as 0.1 MPa. Meanwhile,the pectin content of lemon juice was 0.5% and the light transmittance was 99.6%,which indicated the treatment effect reached best. The ultrasonic-assisted pectinase clarifying the juice is conducive to improve the clarity of juice,and in the subsequent membrane treatment process,it has a significant effect on improving the flux of ultrafiltration membrane and reducing the membrane fouling effect.