In this work, the concentration process of three different tea extracts (medicinal Rosil No. 6, Black, and Forest Fruit teas) using the osmotic evaporation (OE) process, was studied. The effect of the OE process on the content of phenolic compounds and antioxidant activity was evaluated. The concentration process was carried out in a hollow-fibre membrane contactor with an effective surface area of 0.54 m2. The tea extract was circulated through the shell side of the contactor, while a concentrated osmotic solution (CaCl2 5 M) was circulated inside the fibres. The flux, the driving force, and the mass transfer coefficient were evaluated. A decrease of the water flux over time was observed and was attributed only to the decrease of the driving force, caused by the dilution of the osmotic solution. Using a surface area/feed volume ratio of 774 m2·m−3, it is possible to reach a tea concentration of 40% (w/w) in 5 h, with a constant water flux and without losing the phenolic content and antioxidant potential in most teas.
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机译:在这项工作中,研究了使用渗透蒸发(OE)工艺对三种不同茶提取物(药用Rosil 6号,黑茶和森林水果茶)的浓缩过程。评估了OE工艺对酚类化合物含量和抗氧化活性的影响。浓缩过程在有效表面积为0.54 m 2 sup>的中空纤维膜接触器中进行。茶提取物在接触器的壳侧循环,而浓渗透溶液(CaCl2 5 M)在纤维内部循环。评估通量,驱动力和传质系数。观察到水通量随时间减少,这仅归因于由渗透溶液的稀释引起的驱动力的减少。使用774 m 2 sup>·m -3 sup>的表面积/进料体积比,可以在5小时内达到40%(w / w)的茶浓度,具有恒定的水通量,并且不会损失大多数茶中的酚含量和抗氧化能力。
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