Pre-oxidation drying of Cyclopia plant material to eliminate a bottleneck in conventional manufacture of traditional honeybush tea – impact on infusion quality

Abstract

During the conventional production of traditional honeybush tea, the lengthy high-temperature oxidation process creates a bottleneck due to constrained equipment capacity, resulting in a backlog in production during peak harvesting. A delay in processing could cause deterioration of the fresh plant material, and ultimately a poor-quality finished product. Cyclopia subternata, C. genistoides and C. intermedia were used to evaluate the viability of preserving the freshly harvested plant material by pre-oxidation drying until equipment capacity becomes available. The quality of their herbal teas, manufactured by using fresh and dried plant material as raw materials, was assessed in terms of sensory characteristics, colour, turbidity and phenolic composition of the infusions. Pre-oxidation drying did not affect the intensities of the aroma attributes, nor were sweetness and astringency affected (p ≥ 0.05). However, the bitter intensity of C. genistoides infusions was slightly increased (p < 0.05). Pre-oxidation drying also resulted in infusions that were slightly lighter, less red and less yellow. The change in individual and overall phenolic content of the infusions was not consistent between species. The overall phenolic content of the infusions increased for C. genistoides, but decreased for C. subternata and C. intermedia. With sensory properties being key to the quality of honeybush tea, pre-oxidation drying of the plant material may be an effective solution to alleviate the manufacturing bottleneck. Not only could it extend the operating period of factories beyond the harvest season, but processing demands could be levelled out.