果浆酶Pectinex SMASH澄清香蕉汁的机理

The Clarification Mechanism of Banana Juice by Pectinex SMASH

探讨了PectinexSMASH澄清香蕉汁的机理。研究表明,香蕉汁悬浮颗粒主要是由蛋白质与碳水化合物组成,在酸性条件下,带正电荷的蛋白质被带负电荷的果胶包裹形成稳定的混浊体系。澄清前悬浮颗粒的平均粒径为0236μm,属于胶体分散体系,果汁混浊。经PectinexSMASH处理后,悬浮颗粒中果胶被降解从而聚合度降低,悬浮颗粒中带正电荷的蛋白质暴露出来,颗粒Zeta电位降低。带不同电荷的颗粒相互吸引聚集增大,澄清60min时颗粒平均粒径为16986μm,属于不稳定的粗分散体系而容易发生凝沉。通过透射电镜观察发现,香蕉汁悬浮颗粒在澄清前彼此分散且粒径小,澄清后颗粒通过网络结构形成交联聚集体,香蕉汁因悬浮颗粒聚集凝沉而澄清,证实了前人提出的果胶酶澄清果汁的模型。

Clarification mechanism of cloudy banana juice by Pectinex SMASH was investigated in the paper. It was found that the main compounds in suspended particles were proteins and carbohydrates, and the particles were negatively charge on the surface at acidity condition. The average size of suspended particles with negatively charges was 0.236μm, therefore, electrostatic repulsion between the suspended particles made the cloudy colloid dispersing system stable. After enzymatic clarification, pectin content and degree of polymerization in the suspended particles was reduced and lead to the decrease of Zeta-potential. Appearing positive charge resulted from partial enzymatic degradation would attract the neighboring negatively charged particles. The average particle size increased to 16.986μm because of flocculation when clarified for 60min. Ultra microstructures of the suspended particles were observed by transmission electron microscope (TEM), the particles were small and separated from each other before clarification. However, these particles became larger and congregated with each other after enzyme treatment. The results proved the previous model of pectinase clarification mechanism of cloudy juice.