壳聚糖改性对蒙脱石吸附茶饮料中咖啡碱的影响

Chitosan modified montmorillonite and the adsorption effect on caffeine from tea beverage

通过将壳聚糖负载到蒙脱石表面,制备壳聚糖改性蒙脱石,并利用扫描电子显微镜(scanning electron microscope,SEM)、X射线衍射仪技术(X-ray diffraction,XRD)进行表征,探究改性蒙脱石在脱咖啡碱茶饮料中的应用。结果表明,壳聚糖并未插入蒙脱石层间,而是通过电荷相互作用吸附在蒙脱石表面,形成复合吸附剂。蒙脱石负载壳聚糖的量越多,对咖啡碱的吸附能力越弱,对茶多酚的吸附能力越强。以m(蒙脱石)∶m(壳聚糖)=1∶0.01最佳,此时咖啡碱脱除率约(86.01±1.8)%,茶多酚保留率为(84.52±1.01)%。此外,相较于蒙脱石,负载壳聚糖的蒙脱石能明显抑制铁离子溶出。感官评定显示,壳聚糖改性蒙脱石处理的茶饮料色泽的亮度、香气以及整体滋味更佳。

Chitosan was loaded on the surface of montmorillonite to prepare chitosan-modified montmorillonite and characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD)to explore the application of modified montmorillonite in decaffeinated tea beverages.Results showed that chitosan was not inserted between the montmorillonite layer,but was adsorbed on the surface of the montmorillonite by charge interaction to form a composite adsorbent.The more chitosan loaded by montmorillonite,the weaker the adsorption capacity for caffeine and the stronger the adsorption capacity for tea polyphenols.The mass ratio of 1∶0.01(montmorillonite∶chitosan)was the best,at this ratio,the caffeine removal rate was about(96.01±1.8)%and the tea polyphenols retention rate was(84.52±1.01)%.In addition,compared with montmorillonite,chitosan-modified montmorillonite could significantly inhibit the dissolution of iron ions.Sensory evaluation showed that tea beverages had better color brightness,aroma,and overall taste,which were treated with chitosan-modified montmorillonite.