Antioxidant properties and bioactive compounds in rooibos (Aspalathus linearis) and tea (Camellia sinensis) infusions

Rooibos herbal tea prepared from Aspalathus linearis is becoming increasingly popular. The main aim of this study was to compare the differences in the content of antioxidant compounds between green and fermented rooibos, and white, green, Pu-erh, and black Camellia sinensis teas. Overall, higher antioxidant capacity was measured for infusions prepared from unfermented leaves than fermented of both plants. The use of high-performance liquid chromatography-tandem mass spectrometry showed the differences in bioactive compounds between unfermented and fermented samples. Trigonelline, determined for the first time in rooibos, ferulic acid and sinapic acid were mainly found in rooibos infusions in comparison to Camellia sinensis teas where these compounds were in lower amounts. Rooibos infusions and Camellia sinensis teas possessed a similar level of 5-, 4-, 3- and 4,5-caffeoylquinic acids. The level of catechins and epicatechin derivatives was in lower amounts in rooibos infusions compared to green tea infusions. In addition, Principal Component Analysis was done to show the significant difference between these two plants.