茶叶深加工中膜法浓缩技术研究

Study on concentration technology for tea comprehensive processing by membrane system

在中试规模的基础上,以多种当前热门的茶叶深加工制品浓缩前的料液为原料,系统研究了300Da纳滤、200Da纳滤、反渗透、真空蒸发等浓缩方法对不同制品的浓缩效应.结果表明,在加工速溶绿茶时,采用300Da膜进行浓缩的工效较高,得率达98.86%;在去苦味速溶茶、茶黄素或表没食子儿茶素没食子酸酯高纯制品加工中,纳滤浓缩、反渗透浓缩能提高目标产品中相应功能成分的纯度,并依反渗透、200Da纳滤、300Da纳滤次序效果递增,同时,4种方法对功能成分的损失率差异不显著,故采用300Da纳滤浓缩较好;在茶氨酸加工中,各浓缩方法对茶氨酸的纯度均出现负增长,下降的幅度依次为300Da纳滤、200Da纳滤、真空蒸发、反渗透,所以采用反渗透浓缩效果最佳;对产品重金属含量的影响上,纳滤浓缩能显著降低产品中Pb与As的含量.

The concentraction effects of 300Da nano- filtration, 200Da nano- filtration, reverse osmosis and vacuum evaporation for various kinds of tea comprehensive processed products were systematically studied based on the pilot- scaled equipments by using the tea liquor to process the popular products as material. The results showed that 300Da nano- filtrated concentration had the best effective in the processing of instant tea and its yield reached 98.86%. In the processing of de- bitter instant tea, theaflavin or high purity EGCG, nano- filtration and reverse osmosis could enhance their purity effectively, and 300Da nano filtrated concentration had the best effective, then was 200Da nano filtrated concentration and reverse osmosis concentration,at the same time, there were no significant differences of the lost rates of functional components by different methods, so 300Da nano- filtrated concentration is the best in these methods for producing the products. All of concentration methods have the negative effect on the purity of theanine in order of 300Da nano- filtration 〉200Da nano- filtration〉 vacuum evaporation 〉 reverse osmosis, which suggests reverse osmosis concentration is the best for theanine. The effect of different concentrating methods on heavy metals shows thai nano- filtration concentration can decrease the content of Pb and As in final product.