Bitter profiling of phenolic fractions of green Cyclopia genistoides herbal tea

The bitter taste of Cyclopia genistoides infusions is unacceptable to consumers, who are used to the slightly sweet taste of the herbal teas produced from other Cyclopia species. Bitter taste intensities of crude phenolic fractions of a bitter hot water extract of C. genistoides were determined by a trained panel to identify the fraction contributing most to the bitter taste. Fractions, enriched in benzophenones (B), xanthones (X) and flavanones (F), and each tested at their infusion equivalent concentration (IEC) scored 5, 31 and 13 (on a 100-point scale), respectively. Fraction B, containing mostly iriflophenone glucosides, was perceived as not bitter. The major xanthone in fraction X, mangiferin, was significantly (p < 0.05) more bitter than its regio-isomer, isomangiferin, at equal concentration. A mixture of isomangiferin and mangiferin at their IECs was significantly (p < 0.05) less bitter than the mangiferin solution alone, indicating bitter suppression by isomangiferin.