Determination and quality evaluation of green tea extracts through qualitative and quantitative analysis of multi-components by single marker (QAMS).

The quality of tea is mainly attributed to tea polyphenols and caffeine. In this paper, a new strategy for quality evaluation of green tea extracts was explored and verified through qualitative and quantitative analysis of multi-components by single marker (QAMS). Taguchi Design was introduced to evaluate the fluctuations of the relative conversion factors (fx) of tea catechins, gallic acid and caffeine to epigallocatechin gallate. The regression model (Sig.=0.000) and the deviations (R(2)>0.999) between QAMS and normal external standard method proved the consistency of the two methods. Hierarchical cluster analysis and canonical discriminant analysis were employed to classify 26 batches of commercial Longjing green tea extracts (LJGTEs) collected from different producers. The results showed a significant difference in component profile between the samples from different origins. The QAMS method was verified to be an alternative and promising method to comprehensively and effectively control the quality of LJGTEs from different origins.

[The quality specification of grape seed extract].

This paper reiviewed the current situation of quality control of grape seed extract in domestic and international market. Considering the fact that there is no national or industrial technical specifications established for the extract product, the authors suggested that two sets of quality specifications should be established for the grape seed extract. The two sets of specifications are: the high purity grape seed extract should contain polyphenol NLT 95%, monomer NLT 10%; and the grape seed extract with ordinary quality should have a procyanidolic value NLT 95, and monomer NLT 6%.

[Quality control of plant extract].

The current situation of plant extract in domestic and international market was analyzed in the paper. The quality control of 20 plant extracts which have reasonably good sales in USA market was compared and analyzed. The analysis of the quality control of six plant extracts indicated that there were two main reasons leading to the varied quality specifications among different suppliers. One reason was that the plant species utilized by different companies were different. The other reason was that the extraction processes were different among different production plants. Comparing with the significant international suppliers of plant extracts, the product quality of Chinese companies were not satisfactory. It was suggested that chromatography and chromatographic fingerprint techniques should be applied to improve the quality control standard of plant extract in our country.