甘蔗混合汁单宁无硫澄清脱色机理的研究

摘要

依次使用截留分子量为250、100、50 kDa的管式超滤膜来对甘蔗混合汁单宁无硫澄清工艺的一清汁进行过滤，再分别在一级截留液、二级截留液及三级透过液中加入单宁溶液、Ca(HCO3)2溶液及石灰乳进行二步澄清处理，分别检测二步澄清处理前后蔗汁色值，并使用全波长扫描技术分析蔗汁紫外吸收情况，分析单宁钙、Ca(CO3)2对蔗汁的不同分子量色素脱色效果；采用扫描电镜技术对纯水体系和蔗汁体系所生成的单宁钙与碳酸钙沉淀结构进行表征，研究其蔗汁澄清脱色机理。结果表明，单宁钙与碳酸钙可减少蔗汁中含有不饱和键致色物质含量和减少致色物质不饱和健数量，具有良好的脱色作用；单宁钙与碳酸钙晶体具有多孔隙结构，能很好地将蔗汁中有胶体、色素等非糖分吸附形成共沉淀，具有良好澄清效果。%The 1# clarification juice of tannin sulfur-free clarification process were treated by 250, 100, 50 kDa tubular ultra filtration membrane in sequence, then Ca(HCO3)2 solution, tannin solution and lime were added to the first and second state retentates and the third stage permeate, respectively, to discuses the decolorization effect on different molecular weight pigments of tannin precipitation and CaCO3 with UV spectrum scan. The structural characterizations of tannin precipitation and CaCO3 formed in pure water and sugarcane juice were both studied by scanning electron microscopy (SEM). The results indicated that the pigment quantity and unsaturated bonds of pigment in cane juice were reduced by tannin precipitation and CaCO3, which resulted in high decolorization. The tannin precipitation and CaCO3 were of porous structure, and could absorb colloids and pigments of cane juice to formed co-precipitation, resulted in excellent clarification effect.