A balancing act – Optimising harvest season of Cyclopia genistoides (honeybush tea) for enhanced phenolic content and acceptable sensory profile

Abstract

It is challenging to meet the demand for plants with high bioactive content for functional food extract and herbal tea production, with the latter also having an acceptable sensory profile. The optimal harvest season for C. genistoides to maximise phenolic content without compromising sensory quality was determined. Summer produced leaves with higher levels of mangiferin and isomangiferin than winter (P < 0.05), but not autumn and spring (P ≥ 0.05). Despite moderate correlation of the mangiferin and isomangiferin content of the infusions with bitter intensity (R = 0.636 and R = 0.637 respectively, P < 0.05), the summer and autumn harvests produced herbal tea less bitter than the winter and spring harvests (P < 0.05), indicating the possible modulating role of other polyphenols. The autumn harvest delivered herbal tea with a better overall aroma profile, notably higher intensities of the characteristic honeybush aroma notes, ‘fynbos-floral’, ‘fynbos-sweet’ and ‘fruity-sweet’, than the other seasons (P < 0.05). The practical significance of the variation in the phenolic composition and sensory quality of the herbal tea caused by harvest season was limited. Summer or autumn is recommended, achieving high levels of phenolic constituents without detriment to the sensory quality of the herbal tea product.