Rooibos tea: equilibrium and extraction kinetics of aspalathin

South African herbal teas: Aspalathus linearis, Cyclopia spp. and Athrixia phylicoides—A review

“…This method in fact measured the carbonyl groups of the oxidised polyphenolic compounds. The apparent increase in "ascorbic acid" with increasing infusion time as noted by Hesseling et al (1979) is also attributed to enhanced extraction of rooibos polyphenolic compounds with time (Joubert, 1990c;Jaganyi and Wheeler, 2003). Testing of fresh, unfermented rooibos at ARC Infruitec-Nietvoorbij, using a very specific enzymatic method for ascorbic acid, did not indicate its presence (unpublished data).…”

“…Investigation of the extraction kinetics of aspalathin in water at 80 • C showed that ca. 50% is extracted within 5 min, reaching a plateau between 60 and 90 min (Jaganyi and Wheeler, 2003). It is not known what the effect of extraction time and heating would be on the extract antioxidant activity in cellular or in vivo model systems.…”

Sensory characterization of rooibos tea and the development of a rooibos sensory wheel and lexicon

“…The extraction of soluble solids in a rooibos infusion is determined by various factors such as the tea-towater ratio, the length of the infusion and the water temperature (Jaganyi & Wheeler, 2003;Joubert, 1988;Joubert, 1990;Joubert & Hansmann, 1990). The type of water is also critical in terms of the quality of tea infusions.…”

Influence of postharvest processing and storage on the content of phenolic acids and flavonoids in foods

“…The following foods are sources of chalcones: Apples and apple juice [13, 16, 39, 107 -114], apple cider [112,115], tomatoes [74,116], rooibos tea [6, 117,118], and orange juice [119].…”

“…In fermented products however, the contents are much lower (to 0.1 -0.2%) [6]. Reports in [118] indicated that, depending on the extraction conditions, aspalathin concentrations of up to 13 mg/L in the drink had been observed.…”